Stars and Symbiosis: MicroRNA- and MicroRNA*-Mediated Transcript Cleavage Involved in Arbuscular Mycorrhizal Symbiosis1[W][OA

PubMed Central

Devers, Emanuel A.; Branscheid, Anja; May, Patrick; Krajinski, Franziska

2011-01-01

The majority of plants are able to form the arbuscular mycorrhizal (AM) symbiosis in association with AM fungi. During symbiosis development, plant cells undergo a complex reprogramming resulting in profound morphological and physiological changes. MicroRNAs (miRNAs) are important components of the regulatory network of plant cells. To unravel the impact of miRNAs and miRNA-mediated mRNA cleavage on root cell reprogramming during AM symbiosis, we carried out high-throughput (Illumina) sequencing of small RNAs and degradome tags of Medicago truncatula roots. This led to the annotation of 243 novel miRNAs. An increased accumulation of several novel and conserved miRNAs in mycorrhizal roots suggest a role of these miRNAs during AM symbiosis. The degradome analysis led to the identification of 185 root transcripts as mature miRNA and also miRNA*-mediated mRNA cleavage targets. Several of the identified miRNA targets are known to be involved in root symbioses. In summary, the increased accumulation of specific miRNAs and the miRNA-mediated cleavage of symbiosis-relevant genes indicate that miRNAs are an important part of the regulatory network leading to symbiosis development. PMID:21571671

Differentiation as symbiosis.

PubMed

Chigira, M; Watanabe, H

1994-07-01

Preservation of the identity of DNA is the ultimate goal of multicellular organisms. An abnormal DNA sequence in cells within an individual means its parasitic nature in cell society as shown in tumors. Somatic gene arrangement and gene mutation in development may be considered as de novo formation of parasites. It is likely that the developmental process with genetic alterations means symbiosis between altered cells and germ line cells preserving genetic information without alterations, when somatic alteration of DNA sequence is a major mechanism of differentiation. According to the selfish gene theory of Dawkins, germ line cells permit symbiosis when somatic cell society derives clear profit for the replication of original DNA copies.

Computer symbiosis: Emergence of symbiotic behavior through evolution

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ikegami, Takashi; Kaneko, Kunihiko

Symbiosis is altruistic cooperation between distinct species. It is one of the most effective evolutionary processes, but its dynamics are not well understood as yet. A simple model of symbiosis is introduced, where we consider interactions between hosts and parasites and also mutations of hosts and parasites. It is found that a symbiotic state emerges for a suitable range of mutation rates. The symbiotic state is not static, but dynamically oscillates. Harmful parasites violating symbiosis appear periodically, but are rapidly extinguished by hosts and other parasites, and the symbiotic state is recovered. The emergence of ''Tit for Tat'' strategy tomore » maintain symbiosis is discussed. 4 figs.« less

Molecular marker genes for ectomycorrhizal symbiosis

Treesearch

Shiv Hiremath; Carolyn McQuattie; Gopi Podila; Jenise Bauman

2013-01-01

Mycorrhizal symbiosis is a mutually beneficial association very commonly found among most vascular plants. Formation of mycorrhiza happens only between compatible partners and predicting this is often accomplished through a trial and error process. We investigated the possibility of using expression of symbiosis specific genes as markers to predict the formation of...

Symbiosis, Empathy, Suicidal Behavior, and the Family.

ERIC Educational Resources Information Center

Richman, Joseph

1978-01-01

This paper discusses the theoretical concept of symbiosis, as described by Mahler and her co-workers, and its clinical applications in suicidal situations. Also, the practical implications of the concept of symbiosis for assessment and treatment are discussed (Author)

Plant Signaling and Metabolic Pathways Enabling Arbuscular Mycorrhizal Symbiosis.

PubMed

MacLean, Allyson M; Bravo, Armando; Harrison, Maria J

2017-10-01

Plants have lived in close association with arbuscular mycorrhizal (AM) fungi for over 400 million years. Today, this endosymbiosis occurs broadly in the plant kingdom where it has a pronounced impact on plant mineral nutrition. The symbiosis develops deep within the root cortex with minimal alterations in the external appearance of the colonized root; however, the absence of macroscopic alterations belies the extensive signaling, cellular remodeling, and metabolic alterations that occur to enable accommodation of the fungal endosymbiont. Recent research has revealed the involvement of a novel N -acetyl glucosamine transporter and an alpha/beta-fold hydrolase receptor at the earliest stages of AM symbiosis. Calcium channels required for symbiosis signaling have been identified, and connections between the symbiosis signaling pathway and key transcriptional regulators that direct AM-specific gene expression have been established. Phylogenomics has revealed the existence of genes conserved for AM symbiosis, providing clues as to how plant cells fine-tune their biology to enable symbiosis, and an exciting coalescence of genome mining, lipid profiling, and tracer studies collectively has led to the conclusion that AM fungi are fatty acid auxotrophs and that plants provide their fungal endosymbionts with fatty acids. Here, we provide an overview of the molecular program for AM symbiosis and discuss these recent advances. © 2017 American Society of Plant Biologists. All rights reserved.

Teaching Symbiosis.

ERIC Educational Resources Information Center

Harper, G. H.

1985-01-01

Argues that the meaning of the word "symbiosis" be standardized and that it should be used in a broad sense. Also criticizes the orthodox teaching of general principles in this subject and recommends that priority be given to continuity, intimacy, and associated adaptations, rather than to the harm/benefit relationship. (Author/JN)

Study of cnidarian-algal symbiosis in the "omics" age.

PubMed

Meyer, Eli; Weis, Virginia M

2012-08-01

The symbiotic associations between cnidarians and dinoflagellate algae (Symbiodinium) support productive and diverse ecosystems in coral reefs. Many aspects of this association, including the mechanistic basis of host-symbiont recognition and metabolic interaction, remain poorly understood. The first completed genome sequence for a symbiotic anthozoan is now available (the coral Acropora digitifera), and extensive expressed sequence tag resources are available for a variety of other symbiotic corals and anemones. These resources make it possible to profile gene expression, protein abundance, and protein localization associated with the symbiotic state. Here we review the history of "omics" studies of cnidarian-algal symbiosis and the current availability of sequence resources for corals and anemones, identifying genes putatively involved in symbiosis across 10 anthozoan species. The public availability of candidate symbiosis-associated genes leaves the field of cnidarian-algal symbiosis poised for in-depth comparative studies of sequence diversity and gene expression and for targeted functional studies of genes associated with symbiosis. Reviewing the progress to date suggests directions for future investigations of cnidarian-algal symbiosis that include (i) sequencing of Symbiodinium, (ii) proteomic analysis of the symbiosome membrane complex, (iii) glycomic analysis of Symbiodinium cell surfaces, and (iv) expression profiling of the gastrodermal cells hosting Symbiodinium.

Determinant factors of industrial symbiosis: greening Pasir Gudang industrial park

NASA Astrophysics Data System (ADS)

Teh, B. T.; Ho, C. S.; Matsuoka, Y.; Chau, L. W.; Gomi, K.

2014-02-01

Green industry has been identified as an important element in attaining greater sustainability. It calls for harmonizing robust economic growth with environment protection. Industries, particularly in developing and transitional nations such as Malaysia, are in need of a reform. Many experts and international organizations suggest the concept of industrial symbiosis. Mainly, there are successful cases of industrial symbiosis practices around the world. However, there are numerous cases of failure too. As industrial symbiosis is an emerging new approach, with a short history of two decades, a lot of researches are generally focused on narrow context and technical details. There is a lack of concerted efforts to look into the drivers and barriers of industrial symbiosis across different cases. This paper aims to examine the factors influencing the development of industrial symbiosis from various countries to supports such networks to evolve in Pasir Gudang. The findings show institution, law and regulation, finance, awareness and capacity building, technology, research and development, information, collaboration, market, geography proximity, environmental issues and industry structure affect the formation of industrial symbiosis.

Survival through Symbiosis.

ERIC Educational Resources Information Center

Abdi, S. Wali

1992-01-01

Describes symbiosis and its significance in the day-to-day lives of plants and animals. Gives specific examples of mutualism, commensalism, and parasitism in the relationships among fungus and plant roots, animals and bacteria, birds and animals, fish, and predator and prey. (MDH)

Applying industrial symbiosis to chemical industry: A literature review

NASA Astrophysics Data System (ADS)

Cui, Hua; Liu, Changhao

2017-08-01

Chemical industry plays an important role in promoting the development of global economy and human society. However, the negative effects caused by chemical production cannot be ignored, which often leads to serious resource consumption and environmental pollution. It is essential for chemical industry to achieve a sustainable development. Industrial symbiosis is one of the key topics in the field of industrial ecology and circular economy, which has been identified as a creative path leading to sustainability. Based on an extensively searching for literatures on linking industrial symbiosis with chemical industry, this paper aims to review the literatures which involves three aspects: (1) economic and environmental benefits achieved by chemical industry through implementing industrial symbiosis, (2) chemical eco-industrial parks, (3) and safety issues for chemical industry. An outlook is also provided. This paper concludes that: (1) chemical industry can achieve both economic and environmental benefits by implementing industrial symbiosis, (2) establishing eco-industrial parks is essential for chemical industry to implement and improve industrial symbiosis, and (3) there is a close relationship between IS and safety issues of chemical industry.

The engine of the reef: photobiology of the coral–algal symbiosis

PubMed Central

Roth, Melissa S.

2014-01-01

Coral reef ecosystems thrive in tropical oligotrophic oceans because of the relationship between corals and endosymbiotic dinoflagellate algae called Symbiodinium. Symbiodinium convert sunlight and carbon dioxide into organic carbon and oxygen to fuel coral growth and calcification, creating habitat for these diverse and productive ecosystems. Light is thus a key regulating factor shaping the productivity, physiology, and ecology of the coral holobiont. Similar to all oxygenic photoautotrophs, Symbiodinium must safely harvest sunlight for photosynthesis and dissipate excess energy to prevent oxidative stress. Oxidative stress is caused by environmental stressors such as those associated with global climate change, and ultimately leads to breakdown of the coral–algal symbiosis known as coral bleaching. Recently, large-scale coral bleaching events have become pervasive and frequent threatening and endangering coral reefs. Because the coral–algal symbiosis is the biological engine producing the reef, the future of coral reef ecosystems depends on the ecophysiology of the symbiosis. This review examines the photobiology of the coral–algal symbiosis with particular focus on the photophysiological responses and timescales of corals and Symbiodinium. Additionally, this review summarizes the light environment and its dynamics, the vulnerability of the symbiosis to oxidative stress, the abiotic and biotic factors influencing photosynthesis, the diversity of the coral–algal symbiosis, and recent advances in the field. Studies integrating physiology with the developing “omics” fields will provide new insights into the coral–algal symbiosis. Greater physiological and ecological understanding of the coral–algal symbiosis is needed for protection and conservation of coral reefs. PMID:25202301

On Human Symbiosis and the Vicissitudes of Individuation. Infantile Psychosis, Volume 1.

ERIC Educational Resources Information Center

Mahler, Margaret S.

The concepts of symbiosis and separation-individuation are explained, and the symbiosis theory of infantile psychosis is presented. Diagnostic considerations and clinical cases of child psychosis are reviewed; prototypes of mother-child interaction are described; and therapy is discussed. A summary of the symbiosis theory and a bibliography of…

Feathermoss and epiphytic Nostoc cooperate differently: expanding the spectrum of plant–cyanobacteria symbiosis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Warshan, Denis; Espinoza, Josh L.; Stuart, Rhona

Dinitrogen (N2)-fixation by cyanobacteria in symbiosis with feather mosses represents the main pathway of biological N input into boreal forests. Despite its significance, little is known about the gene repertoire needed for the establishment and maintenance of the symbiosis. To determine gene acquisitions or regulatory rewiring allowing cyanobacteria to form this symbiosis, we compared closely related Nostoc strains that were either symbiosis-competent or non-competent, using a proteogenomics approach and a unique experimental setup allowing for controlled chemical and physical contact between partners. Thirty-two protein families were only in the genomes of competent strains, including some never before associated with symbiosis.more » We identified conserved orthologs that were differentially expressed in competent strains, including gene families involved in chemotaxis and motility, NO regulation, sulfate/phosphate transport, sugar metabolism, and glycosyl-modifying and oxidative stress-mediating exoenzymes. In contrast to other cyanobacteria-plant symbioses, the moss-cyanobacteria epiphytic symbiosis is distinct, with the symbiont retaining motility and chemotaxis, and not modulating N-fixation, photosynthesis, GS-GOGAT cycle, and heterocyst formation. Our work expands our knowledge of plant cyanobacterial symbioses, provides an interaction model of this ecologically significant symbiosis, and suggests new currencies, namely nitric oxide and aliphatic sulfonates, may be involved in establishing and maintaining this symbiosis.« less

Signaling events during initiation of arbuscular mycorrhizal symbiosis.

PubMed

Schmitz, Alexa M; Harrison, Maria J

2014-03-01

Under nutrient-limiting conditions, plants will enter into symbiosis with arbuscular mycorrhizal (AM) fungi for the enhancement of mineral nutrient acquisition from the surrounding soil. AM fungi live in close, intracellular association with plant roots where they transfer phosphate and nitrogen to the plant in exchange for carbon. They are obligate fungi, relying on their host as their only carbon source. Much has been discovered in the last decade concerning the signaling events during initiation of the AM symbiosis, including the identification of signaling molecules generated by both partners. This signaling occurs through symbiosis-specific gene products in the host plant, which are indispensable for normal AM development. At the same time, plants have adapted complex mechanisms for avoiding infection by pathogenic fungi, including an innate immune response to general microbial molecules, such as chitin present in fungal cell walls. How it is that AM fungal colonization is maintained without eliciting a defensive response from the host is still uncertain. In this review, we present a summary of the molecular signals and their elicited responses during initiation of the AM symbiosis, including plant immune responses and their suppression. © 2014 Institute of Botany, Chinese Academy of Sciences.

Speciation by Symbiosis: the Microbiome and Behavior

PubMed Central

Shropshire, J. Dylan

2016-01-01

ABSTRACT Species are fundamental units of comparison in biology. The newly discovered importance and ubiquity of host-associated microorganisms are now stimulating work on the roles that microbes can play in animal speciation. We previously synthesized the literature and advanced concepts of speciation by symbiosis with notable attention to hybrid sterility and lethality. Here, we review recent studies and relevant data on microbes as players in host behavior and behavioral isolation, emphasizing the patterns seen in these analyses and highlighting areas worthy of additional exploration. We conclude that the role of microbial symbionts in behavior and speciation is gaining exciting traction and that the holobiont and hologenome concepts afford an evolving intellectual framework to promote research and intellectual exchange between disciplines such as behavior, microbiology, genetics, symbiosis, and speciation. Given the increasing centrality of microbiology in macroscopic life, microbial symbiosis is arguably the most neglected aspect of animal and plant speciation, and studying it should yield a better understanding of the origin of species. PMID:27034284

Global distribution and vertical patterns of a prymnesiophyte–cyanobacteria obligate symbiosis

PubMed Central

Cabello, Ana M; Cornejo-Castillo, Francisco M; Raho, Nicolas; Blasco, Dolors; Vidal, Montserrat; Audic, Stéphane; de Vargas, Colomban; Latasa, Mikel; Acinas, Silvia G; Massana, Ramon

2016-01-01

A marine symbiosis has been recently discovered between prymnesiophyte species and the unicellular diazotrophic cyanobacterium UCYN-A. At least two different UCYN-A phylotypes exist, the clade UCYN-A1 in symbiosis with an uncultured small prymnesiophyte and the clade UCYN-A2 in symbiosis with the larger Braarudosphaera bigelowii. We targeted the prymnesiophyte–UCYN-A1 symbiosis by double CARD-FISH (catalyzed reporter deposition-fluorescence in situ hybridization) and analyzed its abundance in surface samples from the MALASPINA circumnavigation expedition. Our use of a specific probe for the prymnesiophyte partner allowed us to verify that this algal species virtually always carried the UCYN-A symbiont, indicating that the association was also obligate for the host. The prymnesiophyte–UCYN-A1 symbiosis was detected in all ocean basins, displaying a patchy distribution with abundances (up to 500 cells ml−1) that could vary orders of magnitude. Additional vertical profiles taken at the NE Atlantic showed that this symbiosis occupied the upper water column and disappeared towards the Deep Chlorophyll Maximum, where the biomass of the prymnesiophyte assemblage peaked. Moreover, sequences of both prymnesiophyte partners were searched within a large 18S rDNA metabarcoding data set from the Tara-Oceans expedition around the world. This sequence-based analysis supported the patchy distribution of the UCYN-A1 host observed by CARD-FISH and highlighted an unexpected homogeneous distribution (at low relative abundance) of B. bigelowii in the open ocean. Our results demonstrate that partners are always in symbiosis in nature and show contrasted ecological patterns of the two related lineages. PMID:26405830

Global distribution and vertical patterns of a prymnesiophyte-cyanobacteria obligate symbiosis.

PubMed

Cabello, Ana M; Cornejo-Castillo, Francisco M; Raho, Nicolas; Blasco, Dolors; Vidal, Montserrat; Audic, Stéphane; de Vargas, Colomban; Latasa, Mikel; Acinas, Silvia G; Massana, Ramon

2016-03-01

A marine symbiosis has been recently discovered between prymnesiophyte species and the unicellular diazotrophic cyanobacterium UCYN-A. At least two different UCYN-A phylotypes exist, the clade UCYN-A1 in symbiosis with an uncultured small prymnesiophyte and the clade UCYN-A2 in symbiosis with the larger Braarudosphaera bigelowii. We targeted the prymnesiophyte-UCYN-A1 symbiosis by double CARD-FISH (catalyzed reporter deposition-fluorescence in situ hybridization) and analyzed its abundance in surface samples from the MALASPINA circumnavigation expedition. Our use of a specific probe for the prymnesiophyte partner allowed us to verify that this algal species virtually always carried the UCYN-A symbiont, indicating that the association was also obligate for the host. The prymnesiophyte-UCYN-A1 symbiosis was detected in all ocean basins, displaying a patchy distribution with abundances (up to 500 cells ml(-1)) that could vary orders of magnitude. Additional vertical profiles taken at the NE Atlantic showed that this symbiosis occupied the upper water column and disappeared towards the Deep Chlorophyll Maximum, where the biomass of the prymnesiophyte assemblage peaked. Moreover, sequences of both prymnesiophyte partners were searched within a large 18S rDNA metabarcoding data set from the Tara-Oceans expedition around the world. This sequence-based analysis supported the patchy distribution of the UCYN-A1 host observed by CARD-FISH and highlighted an unexpected homogeneous distribution (at low relative abundance) of B. bigelowii in the open ocean. Our results demonstrate that partners are always in symbiosis in nature and show contrasted ecological patterns of the two related lineages.

Nutrient Exchange and Regulation in Arbuscular Mycorrhizal Symbiosis.

PubMed

Wang, Wanxiao; Shi, Jincai; Xie, Qiujin; Jiang, Yina; Yu, Nan; Wang, Ertao

2017-09-12

Most land plants form symbiotic associations with arbuscular mycorrhizal (AM) fungi. These are the most common and widespread terrestrial plant symbioses, which have a global impact on plant mineral nutrition. The establishment of AM symbiosis involves recognition of the two partners and bidirectional transport of different mineral and carbon nutrients through the symbiotic interfaces within the host root cells. Intriguingly, recent discoveries have highlighted that lipids are transferred from the plant host to AM fungus as a major carbon source. In this review, we discuss the transporter-mediated transfer of carbon, nitrogen, phosphate, potassium and sulfate, and present hypotheses pertaining to the potential regulatory mechanisms of nutrient exchange in AM symbiosis. Current challenges and future perspectives on AM symbiosis research are also discussed. Copyright © 2017 The Author. Published by Elsevier Inc. All rights reserved.

DELLA proteins regulate arbuscule formation in arbuscular mycorrhizal symbiosis

PubMed Central

Floss, Daniela S.; Levy, Julien G.; Lévesque-Tremblay, Véronique; Pumplin, Nathan; Harrison, Maria J.

2013-01-01

Most flowering plants are able to form endosymbioses with arbuscular mycorrhizal fungi. In this mutualistic association, the fungus colonizes the root cortex and establishes elaborately branched hyphae, called arbuscules, within the cortical cells. Arbuscule development requires the cellular reorganization of both symbionts, and the resulting symbiotic interface functions in nutrient exchange. A plant symbiosis signaling pathway controls the development of the symbiosis. Several components of the pathway have been identified, but transcriptional regulators that control downstream pathways for arbuscule formation are still unknown. Here we show that DELLA proteins, which are repressors of gibberellic acid (GA) signaling and function at the nexus of several signaling pathways, are required for arbuscule formation. Arbuscule formation is severely impaired in a Medicago truncatula Mtdella1/Mtdella2 double mutant; GA treatment of wild-type roots phenocopies the della double mutant, and a dominant DELLA protein (della1-Δ18) enables arbuscule formation in the presence of GA. Ectopic expression of della1-Δ18 suggests that DELLA activity in the vascular tissue and endodermis is sufficient to enable arbuscule formation in the inner cortical cells. In addition, expression of della1-Δ18 restores arbuscule formation in the symbiosis signaling pathway mutant cyclops/ipd3, indicating an intersection between DELLA and symbiosis signaling for arbuscule formation. GA signaling also influences arbuscule formation in monocots, and a Green Revolution wheat variety carrying dominant DELLA alleles shows enhanced colonization but a limited growth response to arbuscular mycorrhizal symbiosis. PMID:24297892

DELLA proteins regulate arbuscule formation in arbuscular mycorrhizal symbiosis.

PubMed

Floss, Daniela S; Levy, Julien G; Lévesque-Tremblay, Véronique; Pumplin, Nathan; Harrison, Maria J

2013-12-17

Most flowering plants are able to form endosymbioses with arbuscular mycorrhizal fungi. In this mutualistic association, the fungus colonizes the root cortex and establishes elaborately branched hyphae, called arbuscules, within the cortical cells. Arbuscule development requires the cellular reorganization of both symbionts, and the resulting symbiotic interface functions in nutrient exchange. A plant symbiosis signaling pathway controls the development of the symbiosis. Several components of the pathway have been identified, but transcriptional regulators that control downstream pathways for arbuscule formation are still unknown. Here we show that DELLA proteins, which are repressors of gibberellic acid (GA) signaling and function at the nexus of several signaling pathways, are required for arbuscule formation. Arbuscule formation is severely impaired in a Medicago truncatula Mtdella1/Mtdella2 double mutant; GA treatment of wild-type roots phenocopies the della double mutant, and a dominant DELLA protein (della1-Δ18) enables arbuscule formation in the presence of GA. Ectopic expression of della1-Δ18 suggests that DELLA activity in the vascular tissue and endodermis is sufficient to enable arbuscule formation in the inner cortical cells. In addition, expression of della1-Δ18 restores arbuscule formation in the symbiosis signaling pathway mutant cyclops/ipd3, indicating an intersection between DELLA and symbiosis signaling for arbuscule formation. GA signaling also influences arbuscule formation in monocots, and a Green Revolution wheat variety carrying dominant DELLA alleles shows enhanced colonization but a limited growth response to arbuscular mycorrhizal symbiosis.

Speciation by Symbiosis: the Microbiome and Behavior.

PubMed

Shropshire, J Dylan; Bordenstein, Seth R

2016-03-31

Species are fundamental units of comparison in biology. The newly discovered importance and ubiquity of host-associated microorganisms are now stimulating work on the roles that microbes can play in animal speciation. We previously synthesized the literature and advanced concepts of speciation by symbiosis with notable attention to hybrid sterility and lethality. Here, we review recent studies and relevant data on microbes as players in host behavior and behavioral isolation, emphasizing the patterns seen in these analyses and highlighting areas worthy of additional exploration. We conclude that the role of microbial symbionts in behavior and speciation is gaining exciting traction and that the holobiont and hologenome concepts afford an evolving intellectual framework to promote research and intellectual exchange between disciplines such as behavior, microbiology, genetics, symbiosis, and speciation. Given the increasing centrality of microbiology in macroscopic life, microbial symbiosis is arguably the most neglected aspect of animal and plant speciation, and studying it should yield a better understanding of the origin of species. Copyright © 2016 Shropshire and Bordenstein.

Chromium(VI) Toxicity in Legume Plants: Modulation Effects of Rhizobial Symbiosis

PubMed Central

Lushchak, Volodymyr I.

2018-01-01

Most legume species have the ability to establish a symbiotic relationship with soil nitrogen-fixing rhizobacteria that promote plant growth and productivity. There is an increasing evidence of reactive oxygen species (ROS) important role in formation of legume-rhizobium symbiosis and nodule functioning. Environmental pollutants such as chromium compounds can cause damage to rhizobia, legumes, and their symbiosis. In plants, toxic effects of chromium(VI) compounds are associated with the increased production of ROS and oxidative stress development as well as with inhibition of pigment synthesis and modification of virtually all cellular components. These metabolic changes result in inhibition of seed germination and seedling development as well as reduction of plant biomass and crop yield. However, if plants establish symbiosis with rhizobia, heavy metals are accumulated preferentially in nodules decreasing the toxicity of metals to the host plant. This review summarizes data on toxic effects of chromium on legume plants and legume-rhizobium symbiosis. In addition, we discussed the role of oxidative stress in both chromium toxicity and formation of rhizobial symbiosis and use of nodule bacteria for minimizing toxic effects of chromium on plants. PMID:29662899

Impediment to symbiosis establishment between giant clams and Symbiodinium algae due to sterilization of seawater.

PubMed

Kurihara, Takeo; Yamada, Hideaki; Inoue, Ken; Iwai, Kenji; Hatta, Masayuki

2013-01-01

To survive the juvenile stage, giant clam juveniles need to establish a symbiotic relationship with the microalgae Symbiodinium occurring in the environment. The percentage of giant clam juveniles succeeding in symbiosis establishment ("symbiosis rate") is often low, which is problematic for seed producers. We investigated how and why symbiosis rates vary, depending on whether giant clam seeds are continuously reared in UV treated or non treated seawater. Results repeatedly demonstrated that symbiosis rates were lower for UV treated seawater than for non treated seawater. Symbiosis rates were also lower for autoclaved seawater and 0.2-µm filtered seawater than for non treated seawater. The decreased symbiosis rates in various sterilized seawater suggest the possibility that some factors helping symbiosis establishment in natural seawater are weakened owing to sterilization. The possible factors include vitality of giant clam seeds, since additional experiments revealed that survival rates of seeds reared alone without Symbiodinium were lower in sterilized seawater than in non treated seawater. In conclusion, UV treatment of seawater was found to lead to decreased symbiosis rates, which is due possibly to some adverse effects common to the various sterilization techniques and relates to the vitality of the giant clam seeds.

Feathermoss and epiphytic Nostoc cooperate differently: expanding the spectrum of plant–cyanobacteria symbiosis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Warshan, Denis; Espinoza, Josh L.; Stuart, Rhona K.

Dinitrogen (N 2)-fixation by cyanobacteria in symbiosis with feathermosses is the primary pathway of biological nitrogen (N) input into boreal forests. Despite its significance, little is known about the cyanobacterial gene repertoire and regulatory rewiring needed for the establishment and maintenance of the symbiosis. To determine gene acquisitions and regulatory changes allowing cyanobacteria to form and maintain this symbiosis, we compared genomically closely related symbiotic-competent and -incompetent Nostoc strains using a proteogenomics approach and an experimental set up allowing for controlled chemical and physical contact between partners. Thirty-two gene families were found only in the genomes of symbiotic strains, includingmore » some never before associated with cyanobacterial symbiosis. We identified conserved orthologs that were differentially expressed in symbiotic strains, including protein families involved in chemotaxis and motility, NO regulation, sulfate/phosphate transport, and glycosyl-modifying and oxidative stress-mediating exoenzymes. The physical moss–cyanobacteria epiphytic symbiosis is distinct from other cyanobacteria–plant symbioses, with Nostoc retaining motility, and lacking modulation of N 2-fixation, photosynthesis, GS-GOGAT cycle and heterocyst formation. The results expand our knowledge base of plant–cyanobacterial symbioses, provide a model of information and material exchange in this ecologically significant symbiosis, and suggest new currencies, namely nitric oxide and aliphatic sulfonates, may be involved in establishing and maintaining the cyanobacteria–feathermoss symbiosis.« less

Feathermoss and epiphytic Nostoc cooperate differently: expanding the spectrum of plant-cyanobacteria symbiosis.

PubMed

Warshan, Denis; Espinoza, Josh L; Stuart, Rhona K; Richter, R Alexander; Kim, Sea-Yong; Shapiro, Nicole; Woyke, Tanja; C Kyrpides, Nikos; Barry, Kerrie; Singan, Vasanth; Lindquist, Erika; Ansong, Charles; Purvine, Samuel O; M Brewer, Heather; Weyman, Philip D; Dupont, Christopher L; Rasmussen, Ulla

2017-12-01

Dinitrogen (N 2 )-fixation by cyanobacteria in symbiosis with feathermosses is the primary pathway of biological nitrogen (N) input into boreal forests. Despite its significance, little is known about the cyanobacterial gene repertoire and regulatory rewiring needed for the establishment and maintenance of the symbiosis. To determine gene acquisitions and regulatory changes allowing cyanobacteria to form and maintain this symbiosis, we compared genomically closely related symbiotic-competent and -incompetent Nostoc strains using a proteogenomics approach and an experimental set up allowing for controlled chemical and physical contact between partners. Thirty-two gene families were found only in the genomes of symbiotic strains, including some never before associated with cyanobacterial symbiosis. We identified conserved orthologs that were differentially expressed in symbiotic strains, including protein families involved in chemotaxis and motility, NO regulation, sulfate/phosphate transport, and glycosyl-modifying and oxidative stress-mediating exoenzymes. The physical moss-cyanobacteria epiphytic symbiosis is distinct from other cyanobacteria-plant symbioses, with Nostoc retaining motility, and lacking modulation of N 2 -fixation, photosynthesis, GS-GOGAT cycle and heterocyst formation. The results expand our knowledge base of plant-cyanobacterial symbioses, provide a model of information and material exchange in this ecologically significant symbiosis, and suggest new currencies, namely nitric oxide and aliphatic sulfonates, may be involved in establishing and maintaining the cyanobacteria-feathermoss symbiosis.

Feathermoss and epiphytic Nostoc cooperate differently: expanding the spectrum of plant–cyanobacteria symbiosis

PubMed Central

Warshan, Denis; Espinoza, Josh L; Stuart, Rhona K; Richter, R Alexander; Kim, Sea-Yong; Shapiro, Nicole; Woyke, Tanja; C Kyrpides, Nikos; Barry, Kerrie; Singan, Vasanth; Lindquist, Erika; Ansong, Charles; Purvine, Samuel O; M Brewer, Heather; Weyman, Philip D; Dupont, Christopher L; Rasmussen, Ulla

2017-01-01

Dinitrogen (N2)-fixation by cyanobacteria in symbiosis with feathermosses is the primary pathway of biological nitrogen (N) input into boreal forests. Despite its significance, little is known about the cyanobacterial gene repertoire and regulatory rewiring needed for the establishment and maintenance of the symbiosis. To determine gene acquisitions and regulatory changes allowing cyanobacteria to form and maintain this symbiosis, we compared genomically closely related symbiotic-competent and -incompetent Nostoc strains using a proteogenomics approach and an experimental set up allowing for controlled chemical and physical contact between partners. Thirty-two gene families were found only in the genomes of symbiotic strains, including some never before associated with cyanobacterial symbiosis. We identified conserved orthologs that were differentially expressed in symbiotic strains, including protein families involved in chemotaxis and motility, NO regulation, sulfate/phosphate transport, and glycosyl-modifying and oxidative stress-mediating exoenzymes. The physical moss–cyanobacteria epiphytic symbiosis is distinct from other cyanobacteria–plant symbioses, with Nostoc retaining motility, and lacking modulation of N2-fixation, photosynthesis, GS-GOGAT cycle and heterocyst formation. The results expand our knowledge base of plant–cyanobacterial symbioses, provide a model of information and material exchange in this ecologically significant symbiosis, and suggest new currencies, namely nitric oxide and aliphatic sulfonates, may be involved in establishing and maintaining the cyanobacteria–feathermoss symbiosis. PMID:28800136

Feathermoss and epiphytic Nostoc cooperate differently: expanding the spectrum of plant–cyanobacteria symbiosis

DOE PAGES

Warshan, Denis; Espinoza, Josh L.; Stuart, Rhona K.; ...

2017-08-11

Dinitrogen (N 2)-fixation by cyanobacteria in symbiosis with feathermosses is the primary pathway of biological nitrogen (N) input into boreal forests. Despite its significance, little is known about the cyanobacterial gene repertoire and regulatory rewiring needed for the establishment and maintenance of the symbiosis. To determine gene acquisitions and regulatory changes allowing cyanobacteria to form and maintain this symbiosis, we compared genomically closely related symbiotic-competent and -incompetent Nostoc strains using a proteogenomics approach and an experimental set up allowing for controlled chemical and physical contact between partners. Thirty-two gene families were found only in the genomes of symbiotic strains, includingmore » some never before associated with cyanobacterial symbiosis. We identified conserved orthologs that were differentially expressed in symbiotic strains, including protein families involved in chemotaxis and motility, NO regulation, sulfate/phosphate transport, and glycosyl-modifying and oxidative stress-mediating exoenzymes. The physical moss–cyanobacteria epiphytic symbiosis is distinct from other cyanobacteria–plant symbioses, with Nostoc retaining motility, and lacking modulation of N 2-fixation, photosynthesis, GS-GOGAT cycle and heterocyst formation. The results expand our knowledge base of plant–cyanobacterial symbioses, provide a model of information and material exchange in this ecologically significant symbiosis, and suggest new currencies, namely nitric oxide and aliphatic sulfonates, may be involved in establishing and maintaining the cyanobacteria–feathermoss symbiosis.« less

Layers of Symbiosis - Visualizing the Termite Hindgut Microbial Community

PubMed Central

Leadbetter, Jared

2007-01-01

Jared Leadbetter takes us for a nature walk through the diversity of life resident in the termite hindgut - a microenvironment containing 250 different species found nowhere else on Earth. Jared reveals that the symbiosis exhibited by this system is multi-layered and involves not only a relationship between the termite and its gut inhabitants, but also involves a complex web of symbiosis among the gut microbes themselves. PMID:18979002

Human Machine Learning Symbiosis

ERIC Educational Resources Information Center

Walsh, Kenneth R.; Hoque, Md Tamjidul; Williams, Kim H.

2017-01-01

Human Machine Learning Symbiosis is a cooperative system where both the human learner and the machine learner learn from each other to create an effective and efficient learning environment adapted to the needs of the human learner. Such a system can be used in online learning modules so that the modules adapt to each learner's learning state both…

Origin and Evolution of Nitrogen Fixation Genes on Symbiosis Islands and Plasmid in Bradyrhizobium

PubMed Central

Okubo, Takashi; Piromyou, Pongdet; Tittabutr, Panlada; Teaumroong, Neung; Minamisawa, Kiwamu

2016-01-01

The nitrogen fixation (nif) genes of nodule-forming Bradyrhizobium strains are generally located on symbiosis islands or symbiosis plasmids, suggesting that these genes have been transferred laterally. The nif genes of rhizobial and non-rhizobial Bradyrhizobium strains were compared in order to infer the evolutionary histories of nif genes. Based on all codon positions, the phylogenetic tree of concatenated nifD and nifK sequences showed that nifDK on symbiosis islands formed a different clade from nifDK on non-symbiotic loci (located outside of symbiosis islands and plasmids) with elongated branches; however, these genes were located in close proximity, when only the 1st and 2nd codon positions were analyzed. The guanine (G) and cytosine (C) content of the 3rd codon position of nifDK on symbiosis islands was lower than that on non-symbiotic loci. These results suggest that nif genes on symbiosis islands were derived from the non-symbiotic loci of Bradyrhizobium or closely related strains and have evolved toward a lower GC content with a higher substitution rate than the ancestral state. Meanwhile, nifDK on symbiosis plasmids clustered with nifDK on non-symbiotic loci in the tree representing all codon positions, and the GC content of symbiotic and non-symbiotic loci were similar. These results suggest that nif genes on symbiosis plasmids were derived from the non-symbiotic loci of Bradyrhizobium and have evolved with a similar evolutionary pattern and rate as the ancestral state. PMID:27431195

Impediment to Symbiosis Establishment between Giant Clams and Symbiodinium Algae Due to Sterilization of Seawater

PubMed Central

Kurihara, Takeo; Yamada, Hideaki; Inoue, Ken; Iwai, Kenji; Hatta, Masayuki

2013-01-01

To survive the juvenile stage, giant clam juveniles need to establish a symbiotic relationship with the microalgae Symbiodinium occurring in the environment. The percentage of giant clam juveniles succeeding in symbiosis establishment (“symbiosis rate”) is often low, which is problematic for seed producers. We investigated how and why symbiosis rates vary, depending on whether giant clam seeds are continuously reared in UV treated or non treated seawater. Results repeatedly demonstrated that symbiosis rates were lower for UV treated seawater than for non treated seawater. Symbiosis rates were also lower for autoclaved seawater and 0.2-µm filtered seawater than for non treated seawater. The decreased symbiosis rates in various sterilized seawater suggest the possibility that some factors helping symbiosis establishment in natural seawater are weakened owing to sterilization. The possible factors include vitality of giant clam seeds, since additional experiments revealed that survival rates of seeds reared alone without Symbiodinium were lower in sterilized seawater than in non treated seawater. In conclusion, UV treatment of seawater was found to lead to decreased symbiosis rates, which is due possibly to some adverse effects common to the various sterilization techniques and relates to the vitality of the giant clam seeds. PMID:23613802

Are common symbiosis genes required for endophytic rice-rhizobial interactions?

PubMed

Chen, Caiyan; Zhu, Hongyan

2013-09-01

Legume plants are able to establish root nodule symbioses with nitrogen-fixing bacteria, called rhizobia. Recent studies revealed that the root nodule symbiosis has co-opted the signaling pathway that mediates the ancestral mycorrhizal symbiosis that occurs in most land plants. Despite being unable to induce nodulation, rhizobia have been shown to be able to infect and colonize the roots of non-legumes such as rice. One fascinating question is whether establishment of such associations requires the common symbiosis (Sym) genes that are essential for infection of plant cells by mycorrhizal fungi and rhizobia in legumes. Here, we demonstrated that the common Sym genes are not required for endophytic colonization of rice roots by nitrogen-fixing rhizobia.

Heritable symbiosis: The advantages and perils of an evolutionary rabbit hole

PubMed Central

Bennett, Gordon M.; Moran, Nancy A.

2015-01-01

Many eukaryotes have obligate associations with microorganisms that are transmitted directly between generations. A model for heritable symbiosis is the association of aphids, a clade of sap-feeding insects, and Buchnera aphidicola, a gammaproteobacterium that colonized an aphid ancestor 150 million years ago and persists in almost all 5,000 aphid species. Symbiont acquisition enables evolutionary and ecological expansion; aphids are one of many insect groups that would not exist without heritable symbiosis. Receiving less attention are potential negative ramifications of symbiotic alliances. In the short run, symbionts impose metabolic costs. Over evolutionary time, hosts evolve dependence beyond the original benefits of the symbiosis. Symbiotic partners enter into an evolutionary spiral that leads to irreversible codependence and associated risks. Host adaptations to symbiosis (e.g., immune-system modification) may impose vulnerabilities. Symbiont genomes also continuously accumulate deleterious mutations, limiting their beneficial contributions and environmental tolerance. Finally, the fitness interests of obligate heritable symbionts are distinct from those of their hosts, leading to selfish tendencies. Thus, genes underlying the host–symbiont interface are predicted to follow a coevolutionary arms race, as observed for genes governing host–pathogen interactions. On the macroevolutionary scale, the rapid evolution of interacting symbiont and host genes is predicted to accelerate host speciation rates by generating genetic incompatibilities. However, degeneration of symbiont genomes may ultimately limit the ecological range of host species, potentially increasing extinction risk. Recent results for the aphid–Buchnera symbiosis and related systems illustrate that, whereas heritable symbiosis can expand ecological range and spur diversification, it also presents potential perils. PMID:25713367

Heritable symbiosis: The advantages and perils of an evolutionary rabbit hole.

PubMed

Bennett, Gordon M; Moran, Nancy A

2015-08-18

Many eukaryotes have obligate associations with microorganisms that are transmitted directly between generations. A model for heritable symbiosis is the association of aphids, a clade of sap-feeding insects, and Buchnera aphidicola, a gammaproteobacterium that colonized an aphid ancestor 150 million years ago and persists in almost all 5,000 aphid species. Symbiont acquisition enables evolutionary and ecological expansion; aphids are one of many insect groups that would not exist without heritable symbiosis. Receiving less attention are potential negative ramifications of symbiotic alliances. In the short run, symbionts impose metabolic costs. Over evolutionary time, hosts evolve dependence beyond the original benefits of the symbiosis. Symbiotic partners enter into an evolutionary spiral that leads to irreversible codependence and associated risks. Host adaptations to symbiosis (e.g., immune-system modification) may impose vulnerabilities. Symbiont genomes also continuously accumulate deleterious mutations, limiting their beneficial contributions and environmental tolerance. Finally, the fitness interests of obligate heritable symbionts are distinct from those of their hosts, leading to selfish tendencies. Thus, genes underlying the host-symbiont interface are predicted to follow a coevolutionary arms race, as observed for genes governing host-pathogen interactions. On the macroevolutionary scale, the rapid evolution of interacting symbiont and host genes is predicted to accelerate host speciation rates by generating genetic incompatibilities. However, degeneration of symbiont genomes may ultimately limit the ecological range of host species, potentially increasing extinction risk. Recent results for the aphid-Buchnera symbiosis and related systems illustrate that, whereas heritable symbiosis can expand ecological range and spur diversification, it also presents potential perils.

Mutualism Persistence and Abandonment during the Evolution of the Mycorrhizal Symbiosis.

PubMed

Maherali, Hafiz; Oberle, Brad; Stevens, Peter F; Cornwell, William K; McGlinn, Daniel J

2016-11-01

Mutualistic symbioses with mycorrhizal fungi are widespread in plants. The majority of plant species associate with arbuscular mycorrhizal (AM) fungi. By contrast, the minority associate with ectomycorrhizal (EM) fungi, have abandoned the symbiosis and are nonmycorrhizal (NM), or engage in an intermediate, weakly AM symbiosis (AMNM). To understand the processes that maintain the mycorrhizal symbiosis or cause its loss, we reconstructed its evolution using a ∼3,000-species seed plant phylogeny integrated with mycorrhizal state information. Reconstruction indicated that the common ancestor of seed plants most likely associated with AM fungi and that the EM, NM, and AMNM states descended from the AM state. Direct transitions from the AM state to the EM and NM states were infrequent and generally irreversible, implying that natural selection or genetic constraint could promote stasis once a particular state evolved. However, the evolution of the NM state was more frequent via an indirect pathway through the AMNM state, suggesting that weakening of the AM symbiosis is a necessary precursor to mutualism abandonment. Nevertheless, reversions from the AMNM state back to the AM state were an order of magnitude more likely than transitions to the NM state, suggesting that natural selection favors the AM symbiosis over mutualism abandonment.

How drought and salinity affect arbuscular mycorrhizal symbiosis and strigolactone biosynthesis?

PubMed

López-Ráez, Juan A

2016-06-01

This paper reviews the importance of AM symbiosis in alleviating plant stress under unfavourable environmental conditions, making emphasis on the role of strigolactones. A better understanding of the mechanisms that regulate this beneficial association will increase its potential use as an innovative and sustainable strategy in modern agriculture. Plants are very dynamic systems with a great capacity for adaptation to a constantly changing environment. This phenotypic plasticity is particularly advantageous in areas damaged or subjected to intensive agriculture. Nowadays, global crop production systems are intensifying the impact on natural resources, such as water availability. Therefore, there is an urgent need to find more sustainable alternatives. One of the plant strategies to improve phenotypic plasticity is to establish mutualistic beneficial associations with soil microorganisms, such as the arbuscular mycorrhizal (AM) fungi. The establishment of AM symbiosis requires a complex network of interconnected signalling pathways, in which phytohormones play a key role. Strigolactones (SLs) are plant hormones acting as modulators of the coordinated development under nutrient shortage. SLs also act as host detection signals for AM fungi, favouring symbiosis establishment. In this review, current knowledge on the effect of water-related stresses, such as drought and salinity, in AM symbiosis and in SL production is discussed. Likewise, how the symbiosis helps the host plant to alleviate stress symptoms is also reviewed. Finally, we highlight how interactions between hormonal signalling pathways modulate all these responses, especially in the cross-talk between SLs and abscisic acid (ABA). Understanding the intricate mechanisms that regulate the establishment of AM symbiosis and the plant responses under unfavourable conditions will contribute to implement the use of AM fungi as bioprotective agents against these stresses.

Temperature shapes coral-algal symbiosis in the South China Sea

NASA Astrophysics Data System (ADS)

Tong, Haoya; Cai, Lin; Zhou, Guowei; Yuan, Tao; Zhang, Weipeng; Tian, Renmao; Huang, Hui; Qian, Pei-Yuan

2017-01-01

With the increase in sea surface temperature (SST), scleractinian corals are exposed to bleaching threats but may possess certain flexibilities in terms of their associations with symbiotic algae. Previous studies have shown a close symbiosis between coral the and Symbiodinium; however, the spatial variation of the symbiosis and the attribution underlying are not well understood. In the present study, we examined coral-algal symbiosis in Galaxea fascicularis and Montipora spp. from three biogeographic regions across ~10° of latitude in the South China Sea. Analysis of similarities (ANOSIM) indicated a highly flexible coral-algal symbiosis in both G. fascicularis and Montipora spp. and canonical correspondence analysis (CCA) showed that temperature explained 83.2% and 60.1% of the explanatory subclade variations in G. fascicularis and Montipora spp., respectively, which suggested that temperature was the main environmental factor contributing to the diversity of Symbiodinium across the three regions. The geographic specificity of the Symbiodinium phylogeny was identified, revealing possible environmental selection across the three regions. These results suggest that scleractinian corals may have the ability to regulate Symbiodinium community structures under different temperatures and thus be able to adapt to gradual climate change.

Temperature shapes coral-algal symbiosis in the South China Sea

PubMed Central

Tong, Haoya; Cai, Lin; Zhou, Guowei; Yuan, Tao; Zhang, Weipeng; Tian, Renmao; Huang, Hui; Qian, Pei-Yuan

2017-01-01

With the increase in sea surface temperature (SST), scleractinian corals are exposed to bleaching threats but may possess certain flexibilities in terms of their associations with symbiotic algae. Previous studies have shown a close symbiosis between coral the and Symbiodinium; however, the spatial variation of the symbiosis and the attribution underlying are not well understood. In the present study, we examined coral-algal symbiosis in Galaxea fascicularis and Montipora spp. from three biogeographic regions across ~10° of latitude in the South China Sea. Analysis of similarities (ANOSIM) indicated a highly flexible coral-algal symbiosis in both G. fascicularis and Montipora spp. and canonical correspondence analysis (CCA) showed that temperature explained 83.2% and 60.1% of the explanatory subclade variations in G. fascicularis and Montipora spp., respectively, which suggested that temperature was the main environmental factor contributing to the diversity of Symbiodinium across the three regions. The geographic specificity of the Symbiodinium phylogeny was identified, revealing possible environmental selection across the three regions. These results suggest that scleractinian corals may have the ability to regulate Symbiodinium community structures under different temperatures and thus be able to adapt to gradual climate change. PMID:28084322

Rhizobium–legume symbiosis shares an exocytotic pathway required for arbuscule formation

PubMed Central

Ivanov, Sergey; Fedorova, Elena E.; Limpens, Erik; De Mita, Stephane; Genre, Andrea; Bonfante, Paola; Bisseling, Ton

2012-01-01

Endosymbiotic interactions are characterized by the formation of specialized membrane compartments, by the host in which the microbes are hosted, in an intracellular manner. Two well-studied examples, which are of major agricultural and ecological importance, are the widespread arbuscular mycorrhizal symbiosis and the Rhizobium–legume symbiosis. In both symbioses, the specialized host membrane that surrounds the microbes forms a symbiotic interface, which facilitates the exchange of, for example, nutrients in a controlled manner and, therefore, forms the heart of endosymbiosis. Despite their key importance, the molecular and cellular mechanisms underlying the formation of these membrane interfaces are largely unknown. Recent studies strongly suggest that the Rhizobium–legume symbiosis coopted a signaling pathway, including receptor, from the more ancient arbuscular mycorrhizal symbiosis to form a symbiotic interface. Here, we show that two highly homologous exocytotic vesicle-associated membrane proteins (VAMPs) are required for formation of the symbiotic membrane interface in both interactions. Silencing of these Medicago VAMP72 genes has a minor effect on nonsymbiotic plant development and nodule formation. However, it blocks symbiosome as well as arbuscule formation, whereas root colonization by the microbes is not affected. Identification of these VAMP72s as common symbiotic regulators in exocytotic vesicle trafficking suggests that the ancient exocytotic pathway forming the periarbuscular membrane compartment has also been coopted in the Rhizobium–legume symbiosis. PMID:22566631

Type IV Effector Proteins Involved in the Medicago-Sinorhizobium Symbiosis.

PubMed

Nelson, Matthew S; Chun, Chan Lan; Sadowsky, Michael J

2017-01-01

In this study, we investigated genetic elements of the type IV secretion system (T4SS) found in Sinorhizobium spp. and the role they play in symbiosis. Sinorhizobium meliloti and S. medicae each contain a putative T4SS similar to that used by Agrobacterium tumefaciens during pathogenesis. The Cre reporter assay for translocation system was used to validate potential effector proteins. Both S. meliloti and S. medicae contained the effector protein TfeA, which was translocated into the host plant. Sequence analysis revealed the presence of a nod box involved in transcriptional activation of symbiosis-related genes, upstream of the transcriptional regulator (virG) in the Sinorhizobium T4SS. Replicate quantitative reverse transcription-polymerase chain reaction analyses indicated that luteolin, released by roots and seeds of Medicago truncatula, upregulated transcription of tfeA and virG. Mutations in the T4SS apparatus or tfeA alone resulted in reduced numbers of nodules formed on M. truncatula genotypes. In addition, S. meliloti KH46c, which contains a deletion in the T4SS, was less competitive for nodule formation when coinoculated with an equal number of cells of the wild-type strain. To our knowledge, TfeA is the first T4SS effector protein identified in Sinorhizobium spp. Our results indicate that Sinorhizobium i) uses a T4SS during initiation of symbiosis with Medicago spp., and ii) alters Medicago cells in planta during symbiosis. This study also offers additional bioinformatic evidence that several different rhizobial species may use the T4SS in symbiosis with other legumes.

Heavy metal stress in alders: Tolerance and vulnerability of the actinorhizal symbiosis.

PubMed

Bélanger, Pier-Anne; Bellenger, Jean-Philippe; Roy, Sébastien

2015-11-01

Alders have already demonstrated their potential for the revegetation of both mining and industrial sites. These actinorhizal trees and shrubs and the actinobacteria Frankia associate in a nitrogen-fixing symbiosis which could however be negatively affected by the presence of heavy metals, and accumulate them. In our hydroponic assay with black alders, quantification of the roots and shoots metal concentrations showed that, in the absence of stress, symbiosis increases Mo and Ni root content and simultaneously decreases Mo shoot content. Interestingly, the Mo shoot content also decreases in the presence of Ni, Cu, Pb, Zn and Cd for symbiotic alders. In symbiotic alders, Pb shoot translocation was promoted in presence of Pb. On the other hand, Cd exclusion in symbiotic root tissues was observed with Pb and Cd. In the presence of symbiosis, only Cd and Pb showed translocation into aerial tissues when present in the nutrient solution. Moreover, the translocation of Ni to shoot was prevented by symbiosis in the presence of Cd, Ni and Pb. The hydroponic experiment demonstrated that alders benefit from the symbiosis, producing more biomass (total, root and shoot) than non nodulated alders in control condition, and in the presence of metals (Cu, Ni, Zn, Pb and Cd). Heavy metals did not reduce the nodule numbers (SNN), but the presence of Zn or Cd did reduce nodule allocation. Our study suggests that the Frankia-alder symbiosis is a promising (and a compatible) plant-microorganism association for the revegetation of contaminated sites, with minimal risk of metal dispersion. Copyright © 2015 Elsevier Ltd. All rights reserved.

Carbon availability triggers fungal nitrogen uptake and transport in arbuscular mycorrhizal symbiosis

PubMed Central

Fellbaum, Carl R.; Gachomo, Emma W.; Beesetty, Yugandhar; Choudhari, Sulbha; Strahan, Gary D.; Pfeffer, Philip E.; Kiers, E. Toby; Bücking, Heike

2012-01-01

The arbuscular mycorrhizal (AM) symbiosis, formed between the majority of land plants and ubiquitous soil fungi of the phylum Glomeromycota, is responsible for massive nutrient transfer and global carbon sequestration. AM fungi take up nutrients from the soil and exchange them against photosynthetically fixed carbon (C) from the host. Recent studies have demonstrated that reciprocal reward strategies by plant and fungal partners guarantee a “fair trade” of phosphorus against C between partners [Kiers ET, et al. (2011) Science 333:880–882], but whether a similar reward mechanism also controls nitrogen (N) flux in the AM symbiosis is not known. Using mycorrhizal root organ cultures, we manipulated the C supply to the host and fungus and followed the uptake and transport of N sources in the AM symbiosis, the enzymatic activities of arginase and urease, and fungal gene expression in the extraradical and intraradical mycelium. We found that the C supply of the host plant triggers the uptake and transport of N in the symbiosis, and that the increase in N transport is orchestrated by changes in fungal gene expression. N transport in the symbiosis is stimulated only when the C is delivered by the host across the mycorrhizal interface, not when C is supplied directly to the fungal extraradical mycelium in the form of acetate. These findings support the importance of C flux from the root to the fungus as a key trigger for N uptake and transport and provide insight into the N transport regulation in the AM symbiosis. PMID:22308426

AM symbiosis alters phenolic acid content in tomato roots

PubMed Central

Flors, Victor; García, Juan M; Pozo, Maria J

2010-01-01

Arbuscular mycorrhizal (AM) fungi colonize the roots of most plants to establish a mutualistic symbiosis leading to important benefits for plant health. We have recently shown that AM symbiosis alters both transcriptional and hormonal profiles in tomato roots, many of these changes related to plant defense. Here, we analytically demonstrate that the levels of other important defense-related compounds as phenolic acids are also altered in the symbiosis. Both caffeic and chlorogenic acid levels significantly decreased in tomato roots upon mycorrhization, while ferulic acid increased. Moreover, in the case of caffeic acid a differential reduction was observed depending on the colonizing AM fungus. The results confirm that AM associations imply the regulation of plant defense responses, and that the host changes may vary depending on the AM fungus involved. The potential implications of altered phenolic acid levels on plant control over mycorrhizal colonization and in the plant resistance to pathogens is discussed. PMID:21490421

Symbiosis in eukaryotic evolution.

PubMed

López-García, Purificación; Eme, Laura; Moreira, David

2017-12-07

Fifty years ago, Lynn Margulis, inspiring in early twentieth-century ideas that put forward a symbiotic origin for some eukaryotic organelles, proposed a unified theory for the origin of the eukaryotic cell based on symbiosis as evolutionary mechanism. Margulis was profoundly aware of the importance of symbiosis in the natural microbial world and anticipated the evolutionary significance that integrated cooperative interactions might have as mechanism to increase cellular complexity. Today, we have started fully appreciating the vast extent of microbial diversity and the importance of syntrophic metabolic cooperation in natural ecosystems, especially in sediments and microbial mats. Also, not only the symbiogenetic origin of mitochondria and chloroplasts has been clearly demonstrated, but improvement in phylogenomic methods combined with recent discoveries of archaeal lineages more closely related to eukaryotes further support the symbiogenetic origin of the eukaryotic cell. Margulis left us in legacy the idea of 'eukaryogenesis by symbiogenesis'. Although this has been largely verified, when, where, and specifically how eukaryotic cells evolved are yet unclear. Here, we shortly review current knowledge about symbiotic interactions in the microbial world and their evolutionary impact, the status of eukaryogenetic models and the current challenges and perspectives ahead to reconstruct the evolutionary path to eukaryotes. Copyright © 2017 Elsevier Ltd. All rights reserved.

Secondary metabolism in the lichen symbiosis.

PubMed

Calcott, Mark J; Ackerley, David F; Knight, Allison; Keyzers, Robert A; Owen, Jeremy G

2018-03-05

Lichens, which are defined by a core symbiosis between a mycobiont (fungal partner) and a photobiont (photoautotrophic partner), are in fact complex assemblages of microorganisms that constitute a largely untapped source of bioactive secondary metabolites. Historically, compounds isolated from lichens have predominantly been those produced by the dominant fungal partner, and these continue to be of great interest for their unique chemistry and biotechnological potential. In recent years it has become apparent that many photobionts and lichen-associated bacteria also produce a range of potentially valuable molecules. There is evidence to suggest that the unique nature of the symbiosis has played a substantial role in shaping many aspects of lichen chemistry, for example driving bacteria to produce metabolites that do not bring them direct benefit but are useful to the lichen as a whole. This is most evident in studies of cyanobacterial photobionts, which produce compounds that differ from free living cyanobacteria and are unique to symbiotic organisms. The roles that these and other lichen-derived molecules may play in communication and maintaining the symbiosis are poorly understood at present. Nonetheless, advances in genomics, mass spectrometry and other analytical technologies are continuing to illuminate the wealth of biological and chemical diversity present within the lichen holobiome. Implementation of novel biodiscovery strategies such as metagenomic screening, coupled with synthetic biology approaches to reconstitute, re-engineer and heterologously express lichen-derived biosynthetic gene clusters in a cultivable host, offer a promising means for tapping into this hitherto inaccessible wealth of natural products.

Distinct patterns of genetic differentiation among annelids of eastern Pacific hydrothermal vents.

PubMed

Hurtado, L A; Lutz, R A; Vrijenhoek, R C

2004-09-01

Population genetic and phylogenetic analyses of mitochondrial COI from five deep-sea hydrothermal vent annelids provided insights into their dispersal modes and barriers to gene flow. These polychaetes inhabit vent fields located along the East Pacific Rise (EPR) and Galapagos Rift (GAR), where hundreds to thousands of kilometers can separate island-like populations. Long-distance dispersal occurs via larval stages, but larval life histories differ among these taxa. Mitochondrial gene flow between populations of Riftia pachyptila, a siboglinid worm with neutrally buoyant lecithothrophic larvae, is diminished across the Easter Microplate region, which lies at the boundary of Indo-Pacific and Antarctic deep-sea provinces. Populations of the siboglinid Tevnia jerichonana are similarly subdivided. Oasisia alvinae is not found on the southern EPR, but northern EPR populations of this siboglinid are subdivided across the Rivera Fracture Zone. Mitochondrial gene flow of Alvinella pompejana, an alvinellid with large negatively buoyant lecithotrophic eggs and arrested embryonic development, is unimpeded across the Easter Microplate region. Gene flow in the polynoid Branchipolynoe symmytilida also is unimpeded across the Easter Microplate region. However, A. pompejana populations are subdivided across the equator, whereas B. symmitilida populations are subdivided between the EPR and GAR axes. The present findings are compared with similar evidence from codistributed species of annelids, molluscs and crustaceans to identify potential dispersal filters in these eastern Pacific ridge systems.

Eco-Evo-Devo: developmental symbiosis and developmental plasticity as evolutionary agents.

PubMed

Gilbert, Scott F; Bosch, Thomas C G; Ledón-Rettig, Cristina

2015-10-01

The integration of research from developmental biology and ecology into evolutionary theory has given rise to a relatively new field, ecological evolutionary developmental biology (Eco-Evo-Devo). This field integrates and organizes concepts such as developmental symbiosis, developmental plasticity, genetic accommodation, extragenic inheritance and niche construction. This Review highlights the roles that developmental symbiosis and developmental plasticity have in evolution. Developmental symbiosis can generate particular organs, can produce selectable genetic variation for the entire animal, can provide mechanisms for reproductive isolation, and may have facilitated evolutionary transitions. Developmental plasticity is crucial for generating novel phenotypes, facilitating evolutionary transitions and altered ecosystem dynamics, and promoting adaptive variation through genetic accommodation and niche construction. In emphasizing such non-genomic mechanisms of selectable and heritable variation, Eco-Evo-Devo presents a new layer of evolutionary synthesis.

Périgord black truffle genome uncovers evolutionary origins and mechanisms of symbiosis.

PubMed

Martin, Francis; Kohler, Annegret; Murat, Claude; Balestrini, Raffaella; Coutinho, Pedro M; Jaillon, Olivier; Montanini, Barbara; Morin, Emmanuelle; Noel, Benjamin; Percudani, Riccardo; Porcel, Bettina; Rubini, Andrea; Amicucci, Antonella; Amselem, Joelle; Anthouard, Véronique; Arcioni, Sergio; Artiguenave, François; Aury, Jean-Marc; Ballario, Paola; Bolchi, Angelo; Brenna, Andrea; Brun, Annick; Buée, Marc; Cantarel, Brandi; Chevalier, Gérard; Couloux, Arnaud; Da Silva, Corinne; Denoeud, France; Duplessis, Sébastien; Ghignone, Stefano; Hilselberger, Benoît; Iotti, Mirco; Marçais, Benoît; Mello, Antonietta; Miranda, Michele; Pacioni, Giovanni; Quesneville, Hadi; Riccioni, Claudia; Ruotolo, Roberta; Splivallo, Richard; Stocchi, Vilberto; Tisserant, Emilie; Viscomi, Arturo Roberto; Zambonelli, Alessandra; Zampieri, Elisa; Henrissat, Bernard; Lebrun, Marc-Henri; Paolocci, Francesco; Bonfante, Paola; Ottonello, Simone; Wincker, Patrick

2010-04-15

The Périgord black truffle (Tuber melanosporum Vittad.) and the Piedmont white truffle dominate today's truffle market. The hypogeous fruiting body of T. melanosporum is a gastronomic delicacy produced by an ectomycorrhizal symbiont endemic to calcareous soils in southern Europe. The worldwide demand for this truffle has fuelled intense efforts at cultivation. Identification of processes that condition and trigger fruit body and symbiosis formation, ultimately leading to efficient crop production, will be facilitated by a thorough analysis of truffle genomic traits. In the ectomycorrhizal Laccaria bicolor, the expansion of gene families may have acted as a 'symbiosis toolbox'. This feature may however reflect evolution of this particular taxon and not a general trait shared by all ectomycorrhizal species. To get a better understanding of the biology and evolution of the ectomycorrhizal symbiosis, we report here the sequence of the haploid genome of T. melanosporum, which at approximately 125 megabases is the largest and most complex fungal genome sequenced so far. This expansion results from a proliferation of transposable elements accounting for approximately 58% of the genome. In contrast, this genome only contains approximately 7,500 protein-coding genes with very rare multigene families. It lacks large sets of carbohydrate cleaving enzymes, but a few of them involved in degradation of plant cell walls are induced in symbiotic tissues. The latter feature and the upregulation of genes encoding for lipases and multicopper oxidases suggest that T. melanosporum degrades its host cell walls during colonization. Symbiosis induces an increased expression of carbohydrate and amino acid transporters in both L. bicolor and T. melanosporum, but the comparison of genomic traits in the two ectomycorrhizal fungi showed that genetic predispositions for symbiosis-'the symbiosis toolbox'-evolved along different ways in ascomycetes and basidiomycetes.

Nonspecific Symbiosis Between Sophora flavescens and Different Rhizobia.

PubMed

Liu, Yuan Hui; Jiao, Yin Shan; Liu, Li Xue; Wang, Dan; Tian, Chang Fu; Wang, En Tao; Wang, Lei; Chen, Wen Xin; Wu, Shang Ying; Guo, Bao Lin; Guan, Zha Gen; Poinsot, Véréna; Chen, Wen Feng

2018-02-01

We explored the genetic basis of the promiscuous symbiosis of Sophora flavescens with diverse rhizobia. To determine the impact of Nod factors (NFs) on the symbiosis of S. flavescens, nodulation-related gene mutants of representative rhizobial strains were generated. Strains with mutations in common nodulation genes (nodC, nodM, and nodE) failed to nodulate S. flavescens, indicating that the promiscuous nodulation of this plant is strictly dependent on the basic NF structure. Mutations of the NF decoration genes nodH, nodS, nodZ, and noeI did not affect the nodulation of S. flavescens, but these mutations affected the nitrogen-fixation efficiency of nodules. Wild-type Bradyrhizobium diazoefficiens USDA110 cannot nodulate S. flavescens, but we obtained 14 Tn5 mutants of B. diazoefficiens that nodulated S. flavescens. This suggested that the mutations had disrupted a negative regulator that prevents nodulation of S. flavescens, leading to nonspecific nodulation. For Ensifer fredii CCBAU 45436 mutants, the minimal NF structure was sufficient for nodulation of soybean and S. flavescens. In summary, the mechanism of promiscuous symbiosis of S. flavescens with rhizobia might be related to its nonspecific recognition of NF structures, and the host specificity of rhizobia may also be controlled by currently unknown nodulation-related genes.

Positive Gene Regulation by a Natural Protective miRNA Enables Arbuscular Mycorrhizal Symbiosis.

PubMed

Couzigou, Jean-Malo; Lauressergues, Dominique; André, Olivier; Gutjahr, Caroline; Guillotin, Bruno; Bécard, Guillaume; Combier, Jean-Philippe

2017-01-11

Arbuscular mycorrhizal (AM) symbiosis associates most plants with fungi of the phylum Glomeromycota. The fungus penetrates into roots and forms within cortical cell branched structures called arbuscules for nutrient exchange. We discovered that miR171b has a mismatched cleavage site and is unable to downregulate the miR171 family target gene, LOM1 (LOST MERISTEMS 1). This mismatched cleavage site is conserved among plants that establish AM symbiosis, but not in non-mycotrophic plants. Unlike other members of the miR171 family, miR171b stimulates AM symbiosis and is expressed specifically in root cells that contain arbuscules. MiR171b protects LOM1 from negative regulation by other miR171 family members. These findings uncover a unique mechanism of positive post-transcriptional regulation of gene expression by miRNAs and demonstrate its relevance for the establishment of AM symbiosis. Copyright © 2017 Elsevier Inc. All rights reserved.

Plant nodulation inducers enhance horizontal gene transfer of Azorhizobium caulinodans symbiosis island

PubMed Central

Ling, Jun; Wang, Hui; Wu, Ping; Li, Tao; Tang, Yu; Naseer, Nawar; Zheng, Huiming; Masson-Boivin, Catherine; Zhong, Zengtao

2016-01-01

Horizontal gene transfer (HGT) of genomic islands is a driving force of bacterial evolution. Many pathogens and symbionts use this mechanism to spread mobile genetic elements that carry genes important for interaction with their eukaryotic hosts. However, the role of the host in this process remains unclear. Here, we show that plant compounds inducing the nodulation process in the rhizobium-legume mutualistic symbiosis also enhance the transfer of symbiosis islands. We demonstrate that the symbiosis island of the Sesbania rostrata symbiont, Azorhizobium caulinodans, is an 87.6-kb integrative and conjugative element (ICEAc) that is able to excise, form a circular DNA, and conjugatively transfer to a specific site of gly-tRNA gene of other rhizobial genera, expanding their host range. The HGT frequency was significantly increased in the rhizosphere. An ICEAc-located LysR-family transcriptional regulatory protein AhaR triggered the HGT process in response to plant flavonoids that induce the expression of nodulation genes through another LysR-type protein, NodD. Our study suggests that rhizobia may sense rhizosphere environments and transfer their symbiosis gene contents to other genera of rhizobia, thereby broadening rhizobial host-range specificity. PMID:27849579

Plant nodulation inducers enhance horizontal gene transfer of Azorhizobium caulinodans symbiosis island.

PubMed

Ling, Jun; Wang, Hui; Wu, Ping; Li, Tao; Tang, Yu; Naseer, Nawar; Zheng, Huiming; Masson-Boivin, Catherine; Zhong, Zengtao; Zhu, Jun

2016-11-29

Horizontal gene transfer (HGT) of genomic islands is a driving force of bacterial evolution. Many pathogens and symbionts use this mechanism to spread mobile genetic elements that carry genes important for interaction with their eukaryotic hosts. However, the role of the host in this process remains unclear. Here, we show that plant compounds inducing the nodulation process in the rhizobium-legume mutualistic symbiosis also enhance the transfer of symbiosis islands. We demonstrate that the symbiosis island of the Sesbania rostrata symbiont, Azorhizobium caulinodans, is an 87.6-kb integrative and conjugative element (ICE Ac ) that is able to excise, form a circular DNA, and conjugatively transfer to a specific site of gly-tRNA gene of other rhizobial genera, expanding their host range. The HGT frequency was significantly increased in the rhizosphere. An ICE Ac -located LysR-family transcriptional regulatory protein AhaR triggered the HGT process in response to plant flavonoids that induce the expression of nodulation genes through another LysR-type protein, NodD. Our study suggests that rhizobia may sense rhizosphere environments and transfer their symbiosis gene contents to other genera of rhizobia, thereby broadening rhizobial host-range specificity.

A NIN-LIKE PROTEIN mediates nitrate-induced control of root nodule symbiosis in Lotus japonicus.

PubMed

Nishida, Hanna; Tanaka, Sachiko; Handa, Yoshihiro; Ito, Momoyo; Sakamoto, Yuki; Matsunaga, Sachihiro; Betsuyaku, Shigeyuki; Miura, Kenji; Soyano, Takashi; Kawaguchi, Masayoshi; Suzaki, Takuya

2018-02-05

Legumes and rhizobia establish symbiosis in root nodules. To balance the gains and costs associated with the symbiosis, plants have developed two strategies for adapting to nitrogen availability in the soil: plants can regulate nodule number and/or stop the development or function of nodules. Although the former is accounted for by autoregulation of nodulation, a form of systemic long-range signaling, the latter strategy remains largely enigmatic. Here, we show that the Lotus japonicus NITRATE UNRESPONSIVE SYMBIOSIS 1 (NRSYM1) gene encoding a NIN-LIKE PROTEIN transcription factor acts as a key regulator in the nitrate-induced pleiotropic control of root nodule symbiosis. NRSYM1 accumulates in the nucleus in response to nitrate and directly regulates the production of CLE-RS2, a root-derived mobile peptide that acts as a negative regulator of nodule number. Our data provide the genetic basis for how plants respond to the nitrogen environment and control symbiosis to achieve proper plant growth.

Arbuscular mycorrhizal symbiosis mitigates the negative effects of salinity on durum wheat

PubMed Central

Ingraffia, Rosolino; Giambalvo, Dario; Frenda, Alfonso Salvatore

2017-01-01

Arbuscular mycorrhizal (AM) symbiosis is generally considered to be effective in ameliorating the plant tolerance to salt stress. Unfortunately, the comprehension of the mechanisms implicated in salinity stress alleviation by AM symbiosis is far from being complete. Thus, an experiment was performed by growing durum wheat (Triticum durum Desf.) plants under salt-stress conditions to evaluate the influence of AM symbiosis on both the plant growth and the regulation of a number of genes related to salt stress and nutrient uptake. Durum wheat plants were grown outdoors in pots in absence or in presence of salt stress and with or without AM fungi inoculation. The inoculum consisted of a mixture of spores of Rhizophagus irregularis (formerly Glomus intraradices) and Funneliformis mosseae (formerly G. mosseae). Results indicate that AM symbiosis can alleviate the detrimental effects of salt stress on the growth of durum wheat plants. In fact, under salt stress conditions mycorrhizal plants produced more aboveground and root biomass, had higher N uptake and aboveground N concentration, and showed greater stability of plasma membranes compared to non-mycorrhizal plants. Inoculation with AM fungi had no effect on the expression of the N transporter genes AMT1.1, AMT1.2, and NAR2.2, either under no-stress or salt stress conditions, probably due to the fact that plants were grown under optimal N conditions; on the contrary, NRT1.1 was always upregulated by AM symbiosis. Moreover, the level of expression of the drought stress-related genes AQP1, AQP4, PIP1, DREB5, and DHN15.3 observed in the mycorrhizal stressed plants was markedly lower than that observed in the non-mycorrhizal stressed plants and very close to that observed in the non-stressed plants. Our hypothesis is that, in the present study, AM symbiosis did not increase the plant tolerance to salt stress but instead generated a condition in which plants were subjected to a level of salt stress lower than that of non

Arbuscular mycorrhizal symbiosis mitigates the negative effects of salinity on durum wheat.

PubMed

Fileccia, Veronica; Ruisi, Paolo; Ingraffia, Rosolino; Giambalvo, Dario; Frenda, Alfonso Salvatore; Martinelli, Federico

2017-01-01

Arbuscular mycorrhizal (AM) symbiosis is generally considered to be effective in ameliorating the plant tolerance to salt stress. Unfortunately, the comprehension of the mechanisms implicated in salinity stress alleviation by AM symbiosis is far from being complete. Thus, an experiment was performed by growing durum wheat (Triticum durum Desf.) plants under salt-stress conditions to evaluate the influence of AM symbiosis on both the plant growth and the regulation of a number of genes related to salt stress and nutrient uptake. Durum wheat plants were grown outdoors in pots in absence or in presence of salt stress and with or without AM fungi inoculation. The inoculum consisted of a mixture of spores of Rhizophagus irregularis (formerly Glomus intraradices) and Funneliformis mosseae (formerly G. mosseae). Results indicate that AM symbiosis can alleviate the detrimental effects of salt stress on the growth of durum wheat plants. In fact, under salt stress conditions mycorrhizal plants produced more aboveground and root biomass, had higher N uptake and aboveground N concentration, and showed greater stability of plasma membranes compared to non-mycorrhizal plants. Inoculation with AM fungi had no effect on the expression of the N transporter genes AMT1.1, AMT1.2, and NAR2.2, either under no-stress or salt stress conditions, probably due to the fact that plants were grown under optimal N conditions; on the contrary, NRT1.1 was always upregulated by AM symbiosis. Moreover, the level of expression of the drought stress-related genes AQP1, AQP4, PIP1, DREB5, and DHN15.3 observed in the mycorrhizal stressed plants was markedly lower than that observed in the non-mycorrhizal stressed plants and very close to that observed in the non-stressed plants. Our hypothesis is that, in the present study, AM symbiosis did not increase the plant tolerance to salt stress but instead generated a condition in which plants were subjected to a level of salt stress lower than that of non

Preliminary Design of Industrial Symbiosis of Smes Using Material Flow Cost Accounting (MFCA) Method

NASA Astrophysics Data System (ADS)

Astuti, Rahayu Siwi Dwi; Astuti, Arieyanti Dwi; Hadiyanto

2018-02-01

Industrial symbiosis is a collaboration of several industries to share their necessities such material, energy, technology as well as waste management. As a part of industrial ecology, in principle, this system attempts to emulate ecosystem where waste of an organism is being used by another organism, therefore there is no waste in the nature. This system becomes an effort to optimize resources (material and energy) as well as minimize waste. Considerable, in a symbiosis incure material and energy flows among industries. Material and energy in an industry are known as cost carriers, thus flow analysis in this system can be conducted in perspective of material, energy and cost, or called as material flow cost accounting (MFCA) that is an economic and ecological appraisal approach. Previous researches shown that MFCA implementation could be used to evaluate an industry's environmental-related efficiency as well as in planning, business control and decision making. Moreover, the MFCA has been extended to assess environmental performance of SMEs Cluster or industrial symbiosis in SMEs Cluster, even to make preliminary design of an industrial symbiosis base on a major industry. This paper describes the use of MFCA to asses performance of SMEs industrial symbiosis and to improve the performance.

Neo-Symbiosis: The Next Stage in the Evolution of Human Information Interaction.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Griffith, Douglas; Greitzer, Frank L.

In his 1960 paper Man-Machine Symbiosis, Licklider predicted that human brains and computing machines will be coupled in a tight partnership that will think as no human brain has ever thought and process data in a way not approached by the information-handling machines we know today. Today we are on the threshold of resurrecting the vision of symbiosis. While Licklider’s original vision suggested a co-equal relationship, here we discuss an updated vision, neo-symbiosis, in which the human holds a superordinate position in an intelligent human-computer collaborative environment. This paper was originally published as a journal article and is being publishedmore » as a chapter in an upcoming book series, Advances in Novel Approaches in Cognitive Informatics and Natural Intelligence.« less

The promiscuous larvae: flexibility in the establishment of symbiosis in corals

NASA Astrophysics Data System (ADS)

Cumbo, V. R.; Baird, A. H.; van Oppen, M. J. H.

2013-03-01

Coral reefs thrive in part because of the symbiotic partnership between corals and Symbiodinium. While this partnership is one of the keys to the success of coral reef ecosystems, surprisingly little is known about many aspects of coral symbiosis, in particular the establishment and development of symbiosis in host species that acquire symbionts anew in each generation. More specifically, the point at which symbiosis is established (i.e., larva vs. juvenile) remains uncertain, as does the source of free-living Symbiodinium in the environment. In addition, the capacity of host and symbiont to form novel combinations is unknown. To explore patterns of initial association between host and symbiont, larvae of two species of Acropora were exposed to sediment collected from three locations on the Great Barrier Reef. A high proportion of larvae established symbiosis shortly after contact with sediments, and Acropora larvae were promiscuous, taking up multiple types of Symbiodinium. The Symbiodinium types acquired from the sediments reflected the symbiont assemblage within a wide range of cnidarian hosts at each of the three sites, suggesting potential regional differences in the free-living Symbiodinium assemblage. Coral larvae clearly have the capacity to take up Symbiodinium prior to settlement, and sediment is a likely source. Promiscuous larvae allow species to associate with Symbiodinium appropriate for potentially novel environments that may be experienced following dispersal.

Quantitative assessment of urban and industrial symbiosis in Kawasaki, Japan.

PubMed

Van Berkel, Rene; Fujita, Tsuyoshi; Hashimoto, Shizuka; Fujii, Minoru

2009-03-01

Colocated firms can achieve environmental benefit and competitive advantage from exchanging physical resources (known as industrial symbiosis) with each other or with residential areas (referenced here as urban symbiosis). Past research illustrated that economic and environmental benefits appear self-evident, although detailed quantification has only been attempted of symbioses for energy and water utilities. This article provides a complimentary case studyfor Kawasaki, Japan. The 14 documented symbioses connect steel, cement, chemical, and paperfirms and their spin-off recycling businesses. Seven key material exchanges divert annually at least 565 000 tons of waste from incineration or landfill. Four of these collectively present an estimated economic opportunity of 13.3 billion JPY (approximately 130 million USD) annually. Five symbioses involve utilization of byproduct and two sharing of utilities. The others are traditional or new recycling industries that do not specifically benefit from geographic proximity. The synergistic effect of urban and industrial symbiosis is unique. The legislative framework for a recycling-oriented society has contributed to realization of the symbioses, as has the availability of government subsidies through the Eco-Town program.

Independent signalling cues underpin arbuscular mycorrhizal symbiosis and large lateral root induction in rice.

PubMed

Chiu, Chai Hao; Choi, Jeongmin; Paszkowski, Uta

2018-01-01

Perception of arbuscular mycorrhizal fungi (AMF) triggers distinct plant signalling responses for parallel establishment of symbiosis and induction of lateral root formation. Rice receptor kinase CHITIN ELICITOR RECEPTOR KINASE 1 (CERK1) and α/β-fold hydrolase DWARF14-LIKE (D14L) are involved in pre-symbiotic fungal perception. After 6 wk post-inoculation with Rhizophagus irregularis, root developmental responses, fungal colonization and transcriptional responses were monitored in two independent cerk1 null mutants; a deletion mutant lacking D14L, and with D14L complemented as well as their respective wild-type cultivars (cv Nipponbare and Nihonmasari). Here we show that although essential for symbiosis, D14L is dispensable for AMF-induced root architectural modulation, which conversely relies on CERK1. Our results demonstrate uncoupling of symbiosis and the symbiotic root developmental signalling during pre-symbiosis with CERK1 required for AMF-induced root architectural changes. © 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.

Emergy-based assessment on industrial symbiosis: a case of Shenyang Economic and Technological Development Zone.

PubMed

Geng, Yong; Liu, Zuoxi; Xue, Bing; Dong, Huijuan; Fujita, Tsuyoshi; Chiu, Anthony

2014-12-01

Industrial symbiosis is the sharing of services, utility, and by-product resources among industries. This is usually made in order to add value, reduce costs, and improve the environment, and therefore has been taken as an effective approach for developing an eco-industrial park, improving resource efficiency, and reducing pollutant emission. Most conventional evaluation approaches ignored the contribution of natural ecosystem to the development of industrial symbiosis and cannot reveal the interrelations between economic development and environmental protection, leading to a need of an innovative evaluation method. Under such a circumstance, we present an emergy analysis-based evaluation method by employing a case study at Shenyang Economic and Technological Development Zone (SETDZ). Specific emergy indicators on industrial symbiosis, including emergy savings and emdollar value of total emergy savings, were developed so that the holistic picture of industrial symbiosis can be presented. Research results show that nonrenewable inputs, imported resource inputs, and associated services could be saved by 89.3, 32.51, and 15.7 %, and the ratio of emergy savings to emergy of the total energy used would be about 25.58 %, and the ratio of the emdollar value of total emergy savings to the total gross regional product (GRP) of SETDZ would be 34.38 % through the implementation of industrial symbiosis. In general, research results indicate that industrial symbiosis could effectively reduce material and energy consumption and improve the overall eco-efficiency. Such a method can provide policy insights to industrial park managers so that they can raise appropriate strategies on developing eco-industrial parks. Useful strategies include identifying more potential industrial symbiosis opportunities, optimizing energy structure, increasing industrial efficiency, recovering local ecosystems, and improving public and industrial awareness of eco-industrial park policies.

Impacts of domestication on the arbuscular mycorrhizal symbiosis of 27 crop species.

PubMed

Martín-Robles, Nieves; Lehmann, Anika; Seco, Erica; Aroca, Ricardo; Rillig, Matthias C; Milla, Rubén

2018-04-01

The arbuscular mycorrhizal (AM) symbiosis is key to plant nutrition, and hence is potentially key in sustainable agriculture. Fertilization and other agricultural practices reduce soil AM fungi and root colonization. Such conditions might promote the evolution of low mycorrhizal responsive crops. Therefore, we ask if and how evolution under domestication has altered AM symbioses of crops. We measured the effect of domestication on mycorrhizal responsiveness across 27 crop species and their wild progenitors. Additionally, in a subset of 14 crops, we tested if domestication effects differed under contrasting phosphorus (P) availabilities. The response of AM symbiosis to domestication varied with P availability. On average, wild progenitors benefited from the AM symbiosis irrespective of P availability, while domesticated crops only profited under P-limited conditions. Magnitudes and directions of response were diverse among the 27 crops, and were unrelated to phylogenetic affinities or to the coordinated evolution with fine root traits. Our results indicate disruptions in the efficiency of the AM symbiosis linked to domestication. Under high fertilization, domestication could have altered the regulation of resource trafficking between AM fungi and associated plant hosts. Provided that crops are commonly raised under high fertilization, this result has important implications for sustainable agriculture. © 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.

The effect of pseudo-microgravity on the symbiosis of plants and microorganisms

NASA Astrophysics Data System (ADS)

Tomita-Yokotani, Kaori; Maki, Asano; Aoki, Toshio; Tamura, Kenji; Wada, Hidenori; Hashimoto, Hirofumi; Yamashita, Masamichi

The symbiosis of plants and microorganisms is important to conduct agriculture under space environment. However, we have less knowledge on whether this kind of symbiosis can be established under space condition. We examined the functional compounds responsible to symbiosis between rhizobiaum and Lotus japonicus as a model of symbiotic combination. The existence of the substances for their symbiosis, some flavonoids, have already been known from the study of gene expression, but the detail structures have not yet been elucidated. Pseudomicrogravity was generated by the 3D-clinorotation. Twenty flavonoids were found in the extracts of 16 days plants of Lotus japonicus grown under the normal gravity by HPLC. Content of two flavonoids among them was affected by the infection of Mesorhizobium loti to them. It has a possibility that the two flavonoids were key substances for their combination process. The productions of those flavonoids were confirmed also under the pseudo-microgravity. The amount of one flavonoid was increased by both infection of rhizobium and exposure to the normal and pseudo-micro gravity. Chemical species of these flavonoids were identified by LC- ESI/MS and spectroscopic analysis. To show the effects of pseudo-microgravity on the gene expression, enzymic activities related to the functional compounds are evaluated after the rhizobial infection.

The Microbiota, Chemical Symbiosis, and Human Disease

PubMed Central

Redinbo, Matthew R.

2014-01-01

Our understanding of mammalian-microbial mutualism has expanded by combing microbial sequencing with evolving molecular and cellular methods, and unique model systems. Here, the recent literature linking the microbiota to diseases of three of the key mammalian mucosal epithelial compartments – nasal, lung and gastrointestinal (GI) tract – is reviewed with a focus on new knowledge about the taxa, species, proteins and chemistry that promote health and impact progression toward disease. The information presented is further organized by specific diseases now associated with the microbiota:, Staphylococcus aureus infection and rhinosinusitis in the nasal-sinus mucosa; cystic fibrosis (CF), chronic obstructive pulmonary disorder (COPD), and asthma in the pulmonary tissues. For the vast and microbially dynamic GI compartment, several disorders are considered, including obesity, atherosclerosis, Crohn’s disease, ulcerative colitis, drug toxicity, and even autism. Our appreciation of the chemical symbiosis ongoing between human systems and the microbiota continues to grow, and suggest new opportunities for modulating this symbiosis using designed interventions. PMID:25305474

A modified Lotka-Volterra model for the evolution of coordinate symbiosis in energy enterprise

NASA Astrophysics Data System (ADS)

Zhou, Li; Wang, Teng; Lyu, Xiaohuan; Yu, Jing

2018-02-01

Recent developments in energy markets make the operating industries more dynamic and complex, and energy enterprises cooperate more closely in the industrial chain and symbiosis. In order to further discuss the evolution of coordinate symbiosis in energy enterprises, a modified Lotka-Volterra equation is introduced to develop a symbiosis analysis model of energy groups. According to the equilibrium and stability analysis, a conclusion is obtained that if the upstream energy group and the downstream energy group are in symbiotic state, the growth of their utility will be greater than their independent value. Energy enterprises can get mutual benefits and positive promotions in industrial chain by their cooperation.

Differential spatio-temporal expression of carotenoid cleavage dioxygenases regulates apocarotenoid fluxes during AM symbiosis.

PubMed

López-Ráez, Juan A; Fernández, Iván; García, Juan M; Berrio, Estefanía; Bonfante, Paola; Walter, Michael H; Pozo, María J

2015-01-01

Apocarotenoids are a class of compounds that play important roles in nature. In recent years, a prominent role for these compounds in arbuscular mycorrhizal (AM) symbiosis has been shown. They are derived from carotenoids by the action of the carotenoid cleavage dioxygenase (CCD) enzyme family. In the present study, using tomato as a model, the spatio-temporal expression pattern of the CCD genes during AM symbiosis establishment and functioning was investigated. In addition, the levels of the apocarotenoids strigolactones (SLs), C13 α-ionol and C14 mycorradicin (C13/C14) derivatives were analyzed. The results suggest an increase in SLs promoted by the presence of the AM fungus at the early stages of the interaction, which correlated with an induction of the SL biosynthesis gene SlCCD7. At later stages, induction of SlCCD7 and SlCCD1 expression in arbusculated cells promoted the production of C13/C14 apocarotenoid derivatives. We show here that the biosynthesis of apocarotenoids during AM symbiosis is finely regulated throughout the entire process at the gene expression level, and that CCD7 constitutes a key player in this regulation. Once the symbiosis is established, apocarotenoid flux would be turned towards the production of C13/C14 derivatives, thus reducing SL biosynthesis and maintaining a functional symbiosis. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Replicon-Dependent Differentiation of Symbiosis-Related Genes in Sinorhizobium Strains Nodulating Glycine max

PubMed Central

Guo, Hui Juan; Wang, En Tao; Zhang, Xing Xing; Li, Qin Qin; Zhang, Yan Ming; Chen, Wen Xin

2014-01-01

In order to investigate the genetic differentiation of Sinorhizobium strains nodulating Glycine max and related microevolutionary mechanisms, three housekeeping genes (SMc00019, truA, and thrA) and 16 symbiosis-related genes on the chromosome (7 genes), pSymA (6 genes), and pSymB (3 genes) were analyzed. Five distinct species were identified among the test strains by calculating the average nucleotide identity (ANI) of SMc00019-truA-thrA: Sinorhizobium fredii, Sinorhizobium sojae, Sinorhizobium sp. I, Sinorhizobium sp. II, and Sinorhizobium sp. III. These species assignments were also supported by population genetics and phylogenetic analyses of housekeeping genes and symbiosis-related genes on the chromosome and pSymB. Different levels of genetic differentiation were observed among these species or different replicons. S. sojae was the most divergent from the other test species and was characterized by its low intraspecies diversity and limited geographic distribution. Intergenic recombination dominated the evolution of 19 genes from different replicons. Intraspecies recombination happened frequently in housekeeping genes and symbiosis-related genes on the chromosome and pSymB, whereas pSymA genes showed a clear pattern of lateral-transfer events between different species. Moreover, pSymA genes were characterized by a lower level of polymorphism and recombination than those on the chromosome and pSymB. Taken together, genes from different replicons of rhizobia might be involved in the establishment of symbiosis with legumes, but these symbiosis-related genes might have evolved differently according to their corresponding replicons. PMID:24317084

Replicon-dependent differentiation of symbiosis-related genes in Sinorhizobium strains nodulating Glycine max.

PubMed

Guo, Hui Juan; Wang, En Tao; Zhang, Xing Xing; Li, Qin Qin; Zhang, Yan Ming; Tian, Chang Fu; Chen, Wen Xin

2014-02-01

In order to investigate the genetic differentiation of Sinorhizobium strains nodulating Glycine max and related microevolutionary mechanisms, three housekeeping genes (SMc00019, truA, and thrA) and 16 symbiosis-related genes on the chromosome (7 genes), pSymA (6 genes), and pSymB (3 genes) were analyzed. Five distinct species were identified among the test strains by calculating the average nucleotide identity (ANI) of SMc00019-truA-thrA: Sinorhizobium fredii, Sinorhizobium sojae, Sinorhizobium sp. I, Sinorhizobium sp. II, and Sinorhizobium sp. III. These species assignments were also supported by population genetics and phylogenetic analyses of housekeeping genes and symbiosis-related genes on the chromosome and pSymB. Different levels of genetic differentiation were observed among these species or different replicons. S. sojae was the most divergent from the other test species and was characterized by its low intraspecies diversity and limited geographic distribution. Intergenic recombination dominated the evolution of 19 genes from different replicons. Intraspecies recombination happened frequently in housekeeping genes and symbiosis-related genes on the chromosome and pSymB, whereas pSymA genes showed a clear pattern of lateral-transfer events between different species. Moreover, pSymA genes were characterized by a lower level of polymorphism and recombination than those on the chromosome and pSymB. Taken together, genes from different replicons of rhizobia might be involved in the establishment of symbiosis with legumes, but these symbiosis-related genes might have evolved differently according to their corresponding replicons.

Two negative regulatory systems of root nodule symbiosis - how are symbiotic benefits and costs balanced?

PubMed

Nishida, Hanna; Suzaki, Takuya

2018-05-30

Root nodule symbiosis is one of the best-characterized mutualistic relationships between plants-microbes symbiosis, where mainly leguminous species can obtain nitrogen sources fixed by nitrogen-fixing rhizobia through the formation of symbiotic organs root nodules. In order to drive this symbiotic process, plants need to provide carbon sources that should be used for their growth. Therefore, a balance between the benefits of obtaining nitrogen sources and the costs of losing carbon sources needs to be maintained during root nodule symbiosis. Plants have developed at least two negative regulatory systems of root nodule symbiosis. One strategy involves the regulation of nodule number in response to rhizobial infection. For this regulation, a systemic long-range signaling between roots and shoots called autoregulation of nodulation has a pivotal role. Another strategy involves the regulation of root nodule symbiosis in response to nitrate, the most abundant form of nitrogen nutrients in the soil. Recent studies indicate that a long-distance signaling is shared between the two strategies, where NIN and NRSYM1, two paralogous RWP-RK transcription factors, can activate the production of nodulation-related CLE peptides in response to different inputs. Here, we give an overview of such progress in our understanding of molecular mechanisms relevant to the control of the symbiotic balance, including their biological significance.

Man-Computer Symbiosis Through Interactive Graphics: A Survey and Identification of Critical Research Areas.

ERIC Educational Resources Information Center

Knoop, Patricia A.

The purpose of this report was to determine the research areas that appear most critical to achieving man-computer symbiosis. An operational definition of man-computer symbiosis was developed by: (1) reviewing and summarizing what others have said about it, and (2) attempting to distinguish it from other types of man-computer relationships. From…

Rhizobial symbiosis effect on the growth, metal uptake, and antioxidant responses of Medicago lupulina under copper stress.

PubMed

Kong, Zhaoyu; Mohamad, Osama Abdalla; Deng, Zhenshan; Liu, Xiaodong; Glick, Bernard R; Wei, Gehong

2015-08-01

The effects of rhizobial symbiosis on the growth, metal uptake, and antioxidant responses of Medicago lupulina in the presence of 200 mg kg(-1) Cu(2+) throughout different stages of symbiosis development were studied. The symbiosis with Sinorhizobium meliloti CCNWSX0020 induced an increase in plant growth and nitrogen content irrespective of the presence of Cu(2+). The total amount of Cu uptake of inoculated plants significantly increased by 34.0 and 120.4% in shoots and roots, respectively, compared with non-inoculated plants. However, although the rhizobial symbiosis promoted Cu accumulation both in shoots and roots, the increase in roots was much higher than in shoots, thus decreasing the translocation factor and helping Cu phytostabilization. The rate of lipid peroxidation was significantly decreased in both shoots and roots of inoculated vs. non-inoculated plants when measured either 8, 13, or 18 days post-inoculation. In comparison with non-inoculated plants, the activities of superoxide dismutase and ascorbate peroxidase of shoots of inoculated plants exposed to excess Cu were significantly elevated at different stages of symbiosis development; similar increases occurred in the activities of superoxide dismutase, catalase, and glutathione reductase of inoculated roots. The symbiosis with S. meliloti CCNWSX0020 also upregulated the corresponding genes involved in antioxidant responses in the plants treated with excess Cu. The results indicated that the rhizobial symbiosis with S. meliloti CCNWSX0020 not only enhanced plant growth and metal uptake but also improved the responses of plant antioxidant defense to excess Cu stress.

Unethical and Deadly Symbiosis in Higher Education

ERIC Educational Resources Information Center

Crumbley, D. Larry; Flinn, Ronald; Reichelt, Kenneth J.

2012-01-01

As administrators are pressured to increase retention rates in accounting departments, and higher education in general, a deadly symbiosis is occurring. Most students and parents only wish for high grades, so year after year many educators engage in unethical grade inflation and course work deflation. Since administrators use the students to audit…

Carbon availability for the fungus triggers nitrogen uptake and transport in the arbuscular mycorrhizal symbiosis

USDA-ARS?s Scientific Manuscript database

The arbuscular mycorrhizal (AM) symbiosis is characterized by a transfer of nutrients in exchange for carbon. We tested the effect of the carbon availability for the AM fungus Glomus intraradices on nitrogen (N) uptake and transport in the symbiosis. We followed the uptake and transport of 15N and ...

Shoot- and root-borne cytokinin influences arbuscular mycorrhizal symbiosis.

PubMed

Cosme, Marco; Ramireddy, Eswarayya; Franken, Philipp; Schmülling, Thomas; Wurst, Susanne

2016-10-01

The arbuscular mycorrhizal (AM) symbiosis is functionally important for the nutrition and growth of most terrestrial plants. Nearly all phytohormones are employed by plants to regulate the symbiosis with AM fungi, but the regulatory role of cytokinin (CK) is not well understood. Here, we used transgenic tobacco (Nicotiana tabacum) with a root-specific or constitutive expression of CK-degrading CKX genes and the corresponding wild-type to investigate whether a lowered content of CK in roots or in both roots and shoots influences the interaction with the AM fungus Rhizophagus irregularis. Our data indicates that shoot CK has a positive impact on AM fungal development in roots and on the root transcript level of an AM-responsive phosphate transporter gene (NtPT4). A reduced CK content in roots caused shoot and root growth depression following AM colonization, while neither the uptake of phosphorus or nitrogen nor the root transcript levels of NtPT4 were significantly affected. This suggests that root CK may restrict the C availability from the roots to the fungus thus averting parasitism by AM fungi. Taken together, our study indicates that shoot- and root-borne CK have distinct roles in AM symbiosis. We propose a model illustrating how plants may employ CK to regulate nutrient exchange with the ubiquitous AM fungi.

The bifunctional plant receptor, OsCERK1, regulates both chitin-triggered immunity and arbuscular mycorrhizal symbiosis in rice.

PubMed

Miyata, Kana; Kozaki, Toshinori; Kouzai, Yusuke; Ozawa, Kenjirou; Ishii, Kazuo; Asamizu, Erika; Okabe, Yoshihiro; Umehara, Yosuke; Miyamoto, Ayano; Kobae, Yoshihiro; Akiyama, Kohki; Kaku, Hanae; Nishizawa, Yoko; Shibuya, Naoto; Nakagawa, Tomomi

2014-11-01

Plants are constantly exposed to threats from pathogenic microbes and thus developed an innate immune system to protect themselves. On the other hand, many plants also have the ability to establish endosymbiosis with beneficial microbes such as arbuscular mycorrhizal (AM) fungi or rhizobial bacteria, which improves the growth of host plants. How plants evolved these systems managing such opposite plant-microbe interactions is unclear. We show here that knockout (KO) mutants of OsCERK1, a rice receptor kinase essential for chitin signaling, were impaired not only for chitin-triggered defense responses but also for AM symbiosis, indicating the bifunctionality of OsCERK1 in defense and symbiosis. On the other hand, a KO mutant of OsCEBiP, which forms a receptor complex with OsCERK1 and is essential for chitin-triggered immunity, established mycorrhizal symbiosis normally. Therefore, OsCERK1 but not chitin-triggered immunity is required for AM symbiosis. Furthermore, experiments with chimeric receptors showed that the kinase domains of OsCERK1 and homologs from non-leguminous, mycorrhizal plants could trigger nodulation signaling in legume-rhizobium interactions as the kinase domain of Nod factor receptor1 (NFR1), which is essential for triggering the nodulation program in leguminous plants, did. Because leguminous plants are believed to have developed the rhizobial symbiosis on the basis of AM symbiosis, our results suggest that the symbiotic function of ancestral CERK1 in AM symbiosis enabled the molecular evolution to leguminous NFR1 and resulted in the establishment of legume-rhizobia symbiosis. These results also suggest that OsCERK1 and homologs serve as a molecular switch that activates defense or symbiotic responses depending on the infecting microbes. © The Author 2014. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

The genome of Laccaria bicolor provides insights into mycorrhizal symbiosis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Martin, F.; Aerts, A.; Ahren, D.

Mycorrhizal symbioses the union of roots and soil fungi are universal in terrestrial ecosystems and may have been fundamental to land colonization by plants 1, 2. Boreal, temperate and montane forests all depend on ectomycorrhizae1. Identification of the primary factors that regulate symbiotic development and metabolic activity will therefore open the door to understanding the role of ectomycorrhizae in plant development and physiology, allowing the full ecological significance of this symbiosis to be explored. Here we report the genome sequence of the ectomycorrhizal basidiomycete Laccaria bicolor (Fig. 1) and highlight gene sets involved in rhizosphere colonization and symbiosis. This 65-megabasemore » genome assembly contains 20,000 predicted protein-encoding genes and a very large number of transposons and repeated sequences. We detected unexpected genomic features, most notably a battery of effector-type small secreted proteins (SSPs) with unknown function, several of which are only expressed in symbiotic tissues. The most highly expressed SSP accumulates in the proliferating hyphae colonizing the host root. The ectomycorrhizae-specific SSPs probably have a decisive role in the establishment of the symbiosis. The unexpected observation that the genome of L. bicolor lacks carbohydrate-active enzymes involved in degradation of plant cell walls, but maintains the ability to degrade non-plant cell wall polysaccharides, reveals the dual saprotrophic and biotrophic lifestyle of the mycorrhizal fungus that enables it to grow within both soil and living plant roots. The predicted gene inventory of the L. bicolor genome, therefore, points to previously unknown mechanisms of symbiosis operating in biotrophic mycorrhizal fungi. The availability of this genome provides an unparalleled opportunity to develop a deeper understanding of the processes by which symbionts interact with plants within their ecosystem to perform vital functions in the carbon and nitrogen cycles

DELLA proteins regulate expression of a subset of AM symbiosis-induced genes in Medicago truncatula.

PubMed

Floss, Daniela S; Lévesque-Tremblay, Véronique; Park, Hee-Jin; Harrison, Maria J

2016-01-01

The majority of the vascular flowering plants form symbiotic associations with fungi from the phylum Glomeromycota through which both partners gain access to nutrients, either mineral nutrients in the case of the plant, or carbon, in the case of the fungus. (1) The association develops in the roots and requires substantial remodeling of the root cortical cells where branched fungal hyphae, called arbuscules, are housed in a new membrane-bound apoplastic compartment. (2) Nutrient exchange between the symbionts occurs over this interface and its development and maintenance is critical for symbiosis. Previously, we showed that DELLA proteins, which are well known as repressors of gibberellic acid signaling, also regulate development of AM symbiosis and are necessary to enable arbuscule development. (3) Furthermore, constitutive overexpression of a dominant DELLA protein (della1-Δ18) is sufficient to induce transcripts of several AM symbiosis-induced genes, even in the absence of the fungal symbiont. (4) Here we further extend this approach and identify AM symbiosis genes that respond transcriptionally to constitutive expression of a dominant DELLA protein and also genes that do respond to this treatment. Additionally, we demonstrate that DELLAs interact with REQUIRED FOR ARBUSCULE DEVELOPMENT 1 (RAD1) which further extends our knowledge of GRAS factor complexes that have the potential to regulate gene expression during AM symbiosis.

DELLA proteins regulate expression of a subset of AM symbiosis-induced genes in Medicago truncatula

PubMed Central

Floss, Daniela S.; Lévesque-Tremblay, Véronique; Park, Hee-Jin; Harrison, Maria J.

2016-01-01

ABSTRACT The majority of the vascular flowering plants form symbiotic associations with fungi from the phylum Glomeromycota through which both partners gain access to nutrients, either mineral nutrients in the case of the plant, or carbon, in the case of the fungus.1 The association develops in the roots and requires substantial remodeling of the root cortical cells where branched fungal hyphae, called arbuscules, are housed in a new membrane-bound apoplastic compartment.2 Nutrient exchange between the symbionts occurs over this interface and its development and maintenance is critical for symbiosis. Previously, we showed that DELLA proteins, which are well known as repressors of gibberellic acid signaling, also regulate development of AM symbiosis and are necessary to enable arbuscule development.3 Furthermore, constitutive overexpression of a dominant DELLA protein (della1-Δ18) is sufficient to induce transcripts of several AM symbiosis-induced genes, even in the absence of the fungal symbiont.4 Here we further extend this approach and identify AM symbiosis genes that respond transcriptionally to constitutive expression of a dominant DELLA protein and also genes that do respond to this treatment. Additionally, we demonstrate that DELLAs interact with REQUIRED FOR ARBUSCULE DEVELOPMENT 1 (RAD1) which further extends our knowledge of GRAS factor complexes that have the potential to regulate gene expression during AM symbiosis. PMID:26984507

CERBERUS and NSP1 of Lotus japonicus are common symbiosis genes that modulate arbuscular mycorrhiza development.

PubMed

Takeda, Naoya; Tsuzuki, Syusaku; Suzaki, Takuya; Parniske, Martin; Kawaguchi, Masayoshi

2013-10-01

Arbuscular mycorrhizal symbiosis (AMS) and root nodule symbiosis (RNS) are mutualistic plant-microbe interactions that confer nutritional benefits to both partners. Leguminous plants possess a common genetic system for intracellular symbiosis with AM fungi and with rhizobia. Here we show that CERBERUS and NSP1, which respectively encode an E3 ubiquitin ligase and a GRAS transcriptional regulator and which have previously only been implicated in RNS, are involved in AM fungal infection in Lotus japonicus. Hyphal elongation along the longitudinal axis of the root was reduced in the cerberus mutant, giving rise to a lower colonization level. Knockout of NSP1 decreased the frequency of plants colonized by AM fungi or rhizobia. CERBERUS and NSP1 showed different patterns of expression in response to infection with symbiotic microbes. A low constitutive level of CERBERUS expression was observed in the root and an increased level of NSP1 expression was detected in arbuscule-containing cells. Induction of AM marker gene was triggered in both cerberus and nsp1 mutants by infection with symbiotic microbes; however, the mutants showed a weaker induction of marker gene expression than the wild type, mirroring their lower level of colonization. The common symbiosis genes are believed to act in an early signaling pathway for recognition of symbionts and for triggering early symbiotic responses. Our quantitative analysis of symbiotic phenotypes revealed developmental defects of the novel common symbiosis mutants in both symbioses, which demonstrates that common symbiosis mechanisms also contribute to a range of functions at later or different stages of symbiont infection.

Structural basis for regulation of rhizobial nodulation and symbiosis gene expression by the regulatory NolR

USDA-ARS?s Scientific Manuscript database

The symbiosis between rhizobial microbes and host plants involves the coordinated expression of multiple genes, which leads to nodule formation and nitrogen fixation. As part of the transcriptional machinery for nodulation and symbiosis across a range of Rhizobium, NolR serves as a global regulatory...

Phosphorus and Nitrogen Regulate Arbuscular Mycorrhizal Symbiosis in Petunia hybrida

PubMed Central

Nouri, Eva; Breuillin-Sessoms, Florence; Feller, Urs; Reinhardt, Didier

2014-01-01

Phosphorus and nitrogen are essential nutrient elements that are needed by plants in large amounts. The arbuscular mycorrhizal symbiosis between plants and soil fungi improves phosphorus and nitrogen acquisition under limiting conditions. On the other hand, these nutrients influence root colonization by mycorrhizal fungi and symbiotic functioning. This represents a feedback mechanism that allows plants to control the fungal symbiont depending on nutrient requirements and supply. Elevated phosphorus supply has previously been shown to exert strong inhibition of arbuscular mycorrhizal development. Here, we address to what extent inhibition by phosphorus is influenced by other nutritional pathways in the interaction between Petunia hybrida and R. irregularis. We show that phosphorus and nitrogen are the major nutritional determinants of the interaction. Interestingly, the symbiosis-promoting effect of nitrogen starvation dominantly overruled the suppressive effect of high phosphorus nutrition onto arbuscular mycorrhiza, suggesting that plants promote the symbiosis as long as they are limited by one of the two major nutrients. Our results also show that in a given pair of symbiotic partners (Petunia hybrida and R. irregularis), the entire range from mutually symbiotic to parasitic can be observed depending on the nutritional conditions. Taken together, these results reveal complex nutritional feedback mechanisms in the control of root colonization by arbuscular mycorrhizal fungi. PMID:24608923

Phosphorus and nitrogen regulate arbuscular mycorrhizal symbiosis in Petunia hybrida.

PubMed

Nouri, Eva; Breuillin-Sessoms, Florence; Feller, Urs; Reinhardt, Didier

2014-01-01

Phosphorus and nitrogen are essential nutrient elements that are needed by plants in large amounts. The arbuscular mycorrhizal symbiosis between plants and soil fungi improves phosphorus and nitrogen acquisition under limiting conditions. On the other hand, these nutrients influence root colonization by mycorrhizal fungi and symbiotic functioning. This represents a feedback mechanism that allows plants to control the fungal symbiont depending on nutrient requirements and supply. Elevated phosphorus supply has previously been shown to exert strong inhibition of arbuscular mycorrhizal development. Here, we address to what extent inhibition by phosphorus is influenced by other nutritional pathways in the interaction between Petunia hybrida and R. irregularis. We show that phosphorus and nitrogen are the major nutritional determinants of the interaction. Interestingly, the symbiosis-promoting effect of nitrogen starvation dominantly overruled the suppressive effect of high phosphorus nutrition onto arbuscular mycorrhiza, suggesting that plants promote the symbiosis as long as they are limited by one of the two major nutrients. Our results also show that in a given pair of symbiotic partners (Petunia hybrida and R. irregularis), the entire range from mutually symbiotic to parasitic can be observed depending on the nutritional conditions. Taken together, these results reveal complex nutritional feedback mechanisms in the control of root colonization by arbuscular mycorrhizal fungi.

Ready or Not: Microbial Adaptive Responses in Dynamic Symbiosis Environments.

PubMed

Cao, Mengyi; Goodrich-Blair, Heidi

2017-08-01

In mutually beneficial and pathogenic symbiotic associations, microbes must adapt to the host environment for optimal fitness. Both within an individual host and during transmission between hosts, microbes are exposed to temporal and spatial variation in environmental conditions. The phenomenon of phenotypic variation, in which different subpopulations of cells express distinctive and potentially adaptive characteristics, can contribute to microbial adaptation to a lifestyle that includes rapidly changing environments. The environments experienced by a symbiotic microbe during its life history can be erratic or predictable, and each can impact the evolution of adaptive responses. In particular, the predictability of a rhythmic or cyclical series of environments may promote the evolution of signal transduction cascades that allow preadaptive responses to environments that are likely to be encountered in the future, a phenomenon known as adaptive prediction. In this review, we summarize environmental variations known to occur in some well-studied models of symbiosis and how these may contribute to the evolution of microbial population heterogeneity and anticipatory behavior. We provide details about the symbiosis between Xenorhabdus bacteria and Steinernema nematodes as a model to investigate the concept of environmental adaptation and adaptive prediction in a microbial symbiosis. Copyright © 2017 American Society for Microbiology.

WASTE TO VALUE: INCORPORATING INDUSTRIAL SYMBIOSIS FOR SUSTAINABLE INFRASTRUCTURE

EPA Science Inventory

Technical Challenge: Investigators will examine the role of technology innovations as well as environmental justice (EJ) obligations in initiating and implementing urban-industrial symbiosis in Commerce City (CC), CO. The sustainability challenge invol...

Structural basis for regulation of rhizobial nodulation and symbiosis gene expression by the regulatory protein NolR.

PubMed

Lee, Soon Goo; Krishnan, Hari B; Jez, Joseph M

2014-04-29

The symbiosis between rhizobial microbes and host plants involves the coordinated expression of multiple genes, which leads to nodule formation and nitrogen fixation. As part of the transcriptional machinery for nodulation and symbiosis across a range of Rhizobium, NolR serves as a global regulatory protein. Here, we present the X-ray crystal structures of NolR in the unliganded form and complexed with two different 22-base pair (bp) double-stranded operator sequences (oligos AT and AA). Structural and biochemical analysis of NolR reveals protein-DNA interactions with an asymmetric operator site and defines a mechanism for conformational switching of a key residue (Gln56) to accommodate variation in target DNA sequences from diverse rhizobial genes for nodulation and symbiosis. This conformational switching alters the energetic contributions to DNA binding without changes in affinity for the target sequence. Two possible models for the role of NolR in the regulation of different nodulation and symbiosis genes are proposed. To our knowledge, these studies provide the first structural insight on the regulation of genes involved in the agriculturally and ecologically important symbiosis of microbes and plants that leads to nodule formation and nitrogen fixation.

Symbiosis initiation in the bacterially luminous sea urchin cardinalfish Siphamia versicolor.

PubMed

Dunlap, P V; Gould, A L; Wittenrich, M L; Nakamura, M

2012-09-01

To determine how each new generation of the sea urchin cardinalfish Siphamia versicolor acquires the symbiotic luminous bacterium Photobacterium mandapamensis, and when in its development the S. versicolor initiates the symbiosis, procedures were established for rearing S. versicolor larvae in an aposymbiotic state. Under the conditions provided, larvae survived and developed for 28 days after their release from the mouths of males. Notochord flexion began at 8 days post release (dpr). By 28 dpr, squamation was evident and the caudal complex was complete. The light organ remained free of bacteria but increased in size and complexity during development of the larvae. Thus, aposymbiotic larvae of the fish can survive and develop for extended periods, major components of the luminescence system develop in the absence of the bacteria and the bacteria are not acquired directly from a parent, via the egg or during mouth brooding. Presentation of the symbiotic bacteria to aposymbiotic larvae at 8-10 dpr, but not earlier, led to initiation of the symbiosis. Upon colonization of the light organ, the bacterial population increased rapidly and cells forming the light-organ chambers exhibited a differentiated appearance. Therefore, the light organ apparently first becomes receptive to colonization after 1 week post-release development, the symbiosis is initiated by bacteria acquired from the environment and bacterial colonization induces morphological changes in the nascent light organ. The abilities to culture larvae of S. versicolor for extended periods and to initiate the symbiosis in aposymbiotic larvae are key steps in establishing the experimental tractability of this highly specific vertebrate and microbe mutualism. © 2012 The Authors. Journal of Fish Biology © 2012 The Fisheries Society of the British Isles.

Pilot testing model to uncover industrial symbiosis in Brazilian industrial clusters.

PubMed

Saraceni, Adriana Valélia; Resende, Luis Mauricio; de Andrade Júnior, Pedro Paulo; Pontes, Joseane

2017-04-01

The main objective of this study was to create a pilot model to uncover industrial symbiosis practices in Brazilian industrial clusters. For this purpose, a systematic revision was conducted in journals selected from two categories of the ISI Web of Knowledge: Engineering, Environmental and Engineering, Industrial. After an in-depth revision of literature, results allowed the creation of an analysis structure. A methodology based on fuzzy logic was applied and used to attribute the weights of industrial symbiosis variables. It was thus possible to extract the intensity indicators of the interrelations required to analyse the development level of each correlation between the variables. Determination of variables and their weights initially resulted in a framework for the theory of industrial symbiosis assessments. Research results allowed the creation of a pilot model that could precisely identify the loopholes or development levels in each sphere. Ontology charts for data analysis were also generated. This study contributes to science by presenting the foundations for building an instrument that enables application and compilation of the pilot model, in order to identify opportunity to symbiotic development, which derives from "uncovering" existing symbioses.

[Effect of five fungicides on growth of Glycyrrhiza uralensis and efficiency of mycorrhizal symbiosis].

PubMed

Li, Peng-ying; Yang, Guang; Zhou, Xiu-teng; Zhou, Liane-yun; Shao, Ai-juan; Chen, Mei-lan

2015-12-01

In order to obtain the fungicides with minimal impact on efficiency of mycorrhizal symbiosis, the effect of five fungicides including polyoxins, jinggangmycins, thiophanate methylate, chlorothalonil and carbendazim on the growth of medicinal plant and efficiency of mycorrhizal symbiosis were studied. Pot cultured Glycyrrhiza uralensis was treated with different fungicides with the concentration that commonly used in the field. 60 d after treated with fungicides, infection rate, infection density, biomass indexes, photosyn- thetic index and the content of active component were measured. Experimental results showed that carbendazim had the strongest inhibition on mycorrhizal symbiosis effect. Carbendazim significantly inhibited the mycorrhizal infection rate, significantly suppressed the actual photosynthetic efficiency of G. uralensis and the most indicators of biomass. Polyoxins showed the lowest inhibiting affection. Polyoxins had no significant effect on mycorrhizal infection rate, the actual photosynthetic efficiency of G. uralensis and the most indicators of biomass. The other three fungicides also had an inhibitory effect on efficiency of mycorrhizal symbiosis, and the inhibition degrees were all between polyoxins's and carbendazim's. The author considered that fungicide's inhibition degree on mycorrhizal effect might be related with the species of fungicides, so the author suggested that the farmer should try to choose bio-fungicides like polyoxins.

Symbiosis limits establishment of legumes outside their native range at a global scale

PubMed Central

Simonsen, Anna K.; Dinnage, Russell; Barrett, Luke G.; Prober, Suzanne M.; Thrall, Peter H.

2017-01-01

Microbial symbiosis is integral to plant growth and reproduction, but its contribution to global patterns of plant distribution is unknown. Legumes (Fabaceae) are a diverse and widely distributed plant family largely dependent on symbiosis with nitrogen-fixing rhizobia, which are acquired from soil after germination. This dependency is predicted to limit establishment in new geographic areas, owing to a disruption of compatible host-symbiont associations. Here we compare non-native establishment patterns of symbiotic and non-symbiotic legumes across over 3,500 species, covering multiple independent gains and losses of rhizobial symbiosis. We find that symbiotic legume species have spread to fewer non-native regions compared to non-symbiotic legumes, providing strong support for the hypothesis that lack of suitable symbionts or environmental conditions required for effective nitrogen-fixation are driving these global introduction patterns. These results highlight the importance of mutualisms in predicting non-native species establishment and the potential impacts of microbial biogeography on global plant distributions. PMID:28387250

Coral Reef Genomics: Developing tools for functional genomics ofcoral symbiosis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schwarz, Jodi; Brokstein, Peter; Manohar, Chitra

Symbioses between cnidarians and dinoflagellates in the genus Symbiodinium are widespread in the marine environment. The importance of this symbiosis to reef-building corals and reef nutrient and carbon cycles is well documented, but little is known about the mechanisms by which the partners establish and regulate the symbiosis. Because the dinoflagellate symbionts live inside the cells of their host coral, the interactions between the partners occur on cellular and molecular levels, as each partner alters the expression of genes and proteins to facilitate the partnership. These interactions can examined using high-throughput techniques that allow thousands of genes to be examinedmore » simultaneously. We are developing the groundwork so that we can use DNA microarray profiling to identify genes involved in the Montastraea faveolata and Acropora palmata symbioses. Here we report results from the initial steps in this microarray initiative, that is, the construction of cDNA libraries from 4 of 16 target stages, sequencing of 3450 cDNA clones to generate Expressed Sequenced Tags (ESTs), and annotation of the ESTs to identify candidate genes to include in the microarrays. An understanding of how the coral-dinoflagellate symbiosis is regulated will have implications for atmospheric and ocean sciences, conservation biology, the study and diagnosis of coral bleaching and disease, and comparative studies of animal-protest interactions.« less

Zooxanthellar symbiosis in planula larvae of the coral Pocillopora damicornis.

PubMed

Gaither, Michelle R; Rowan, Rob

2010-04-30

We characterized the planular-zooxanthellae symbiosis of the coral Pocillopora damicornis using criteria that are familiar in studies on corals. Similar to adult corals, planulae exhibited photoacclimation, as changes in symbiont chlorophyll a (chl a); changes in the light-saturation constant for photosynthesis (I(k)); and, at insufficient light, fewer zooxanthellae, decreased respiration, increased weight loss, and increased sensitivity to photoinhibition. Numbers of zooxanthellae in newly-released planulae varied by at least three-fold within broods. Planulae with low versus high numbers of zooxanthellae (termed pale versus dark planulae, respectively) did not differ in symbiont chl-a content, I(k), or biomass-specific rate of dark respiration. Pale planulae had lower rates of photosynthesis, but this difference vanished after three weeks, when zooxanthellar numbers increased by 225% in pale planulae and by 31% in dark planulae. Numbers of zooxanthellae also increased significantly in planulae cultured in ammonium-enriched seawater; ammonium also apparently prevented weight loss and induced settlement. Approximately 70% of photosynthetically-fixed carbon (labeled using (14)C) apparently was translocated from the zooxanthellae to their host. A comparison of planulae cultured at 0.3% versus 11% sunlight suggested that photosynthesis provided ~ 31% of the energy utilized by the latter. Overall, we conclude that the physiology of symbiosis in planulae of P. damicornis is broadly similar to symbiosis physiology in adult corals.

The Genome of Laccaria Bi color Provides Insights into Mycorrhizal Symbiosis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Martin, F; Aerts, A.; Ahren, D

Mycorrhizal symbioses the union of roots and soil fungi are universal in terrestrial ecosystems and may have been fundamental to land colonization by plants1,2. Boreal, temperate and montane forests all depend on ectomycorrhizae1. Identification of the primary factors that regulate symbiotic development and metabolic activity will therefore open the door to understanding the role of ectomycorrhizae in plant development and physiology, allowing the full ecological significance of this symbiosis to be explored. Here we report the genome sequence of the ectomycorrhizal basidiomycete Laccaria bicolor (Fig. 1) and highlight gene sets involved in rhizosphere colonization and symbiosis. This 65-megabase genome assemblymore » contains 20,000 predicted protein-encoding genes and a very large number of transposons and repeated sequences. We detected unexpected genomic features, most notably a battery of effector-type small secreted proteins (SSPs) with unknown function, several of which are only expressed in symbiotic tissues. The most highly expressed SSP accumulates in the proliferating hyphae colonizing the host root. The ectomycorrhizae-specific SSPs probably have a decisive role in the establishment of the symbiosis. The unexpected observation that the genome of L. bicolor lacks carbohydrate-active enzymes involved in degradation of plant cell walls, but maintains the ability to degrade non-plant cell wall polysaccharides, reveals the dual saprotrophic and biotrophic lifestyle of the mycorrhizal fungus that enables it to grow within both soil and living plant roots. The predicted gene inventory of the L. bicolor genome, therefore, points to previously unknown mechanisms of symbiosis operating in biotrophic mycorrhizal fungi. The availability of this genome provides an unparalleled opportunity to develop a deeper understanding of the processes by which symbionts interact with plants within their ecosystem to perform vital functions in the carbon and nitrogen cycles

Menthol-induced bleaching rapidly and effectively provides experimental aposymbiotic sea anemones (Aiptasia sp.) for symbiosis investigations.

PubMed

Matthews, Jennifer L; Sproles, Ashley E; Oakley, Clinton A; Grossman, Arthur R; Weis, Virginia M; Davy, Simon K

2016-02-01

Experimental manipulation of the symbiosis between cnidarians and photosynthetic dinoflagellates (Symbiodinium spp.) is crucial to advancing the understanding of the cellular mechanisms involved in host-symbiont interactions, and overall coral reef ecology. The anemone Aiptasia sp. is a model for cnidarian-dinoflagellate symbiosis, and notably it can be rendered aposymbiotic (i.e. dinoflagellate-free) and re-infected with a range of Symbiodinium types. Various methods exist for generating aposymbiotic hosts; however, they can be hugely time consuming and not wholly effective. Here, we optimise a method using menthol for production of aposymbiotic Aiptasia. The menthol treatment produced aposymbiotic hosts within just 4 weeks (97-100% symbiont loss), and the condition was maintained long after treatment when anemones were held under a standard light:dark cycle. The ability of Aiptasia to form a stable symbiosis appeared to be unaffected by menthol exposure, as demonstrated by successful re-establishment of the symbiosis when anemones were experimentally re-infected. Furthermore, there was no significant impact on photosynthetic or respiratory performance of re-infected anemones. © 2016. Published by The Company of Biologists Ltd.

Repeated loss of coloniality and symbiosis in scleractinian corals

PubMed Central

Barbeitos, Marcos S.; Romano, Sandra L.; Lasker, Howard R.

2010-01-01

The combination of coloniality and symbiosis in Scleractinia is thought to confer competitive advantage over other benthic invertebrates, and it is likely the key factor for the dominance of corals in tropical reefs. However, the extant Scleractinia are evenly split between zooxanthellate and azooxanthellate species. Most azooxanthellate species are solitary and nearly absent from reefs, but have much wider geographic and bathymetric distributions than reef corals. Molecular phylogenetic analyses have repeatedly recovered clades formed by colonial/zooxanthellate and solitary/azooxanthellate taxa, suggesting that coloniality and symbiosis were repeatedly acquired and/or lost throughout the history of the Scleractinia. Using Bayesian ancestral state reconstruction, we found that symbiosis was lost at least three times and coloniality lost at least six times, and at least two instances in which both characters were lost. All of the azooxanthellate lineages originated from ancestors that were reconstructed as symbiotic, corroborating the onshore–offshore diversification trend recorded in marine taxa. Symbiotic sister taxa of two of these descendant lineages are extant in Caribbean reefs but disappeared from the Mediterranean before the end of the Miocene, whereas extant azooxanthellate lineages have trans-Atlantic distributions. Thus, the phyletic link between reef and nonreef communities may have played an important role in the dynamics of extinction and recovery that marks the evolutionary history of scleractinians, and some reef lineages may have escaped local extinction by diversifying into offshore environments. However, this macroevolutionary mechanism offers no hope of mitigating the effects of climate change on coral reefs in the next century. PMID:20547851

Transport properties and regulatory roles of nitrogen in arbuscular mycorrhizal symbiosis.

PubMed

Chen, Aiqun; Gu, Mian; Wang, Shuangshuang; Chen, Jiadong; Xu, Guohua

2018-02-01

Many terrestrial plants can form root symbiosis with beneficial microorganisms for enhancing uptake of mineral nutrients or increasing fitness to adverse environmental challenges. Arbuscular mycorrhizal (AM) symbiosis that is formed by AM fungi and the roots of vascular flowering plants is the most widespread mutualistic associations in nature. As a typical endosymbiosis, AM interactions involves the differentiation of both symbionts to create novel symbiotic interfaces within the root cells, and requires a continuous nutrient exchange between the two partners. AM plants have two pathways for nutrient uptake, either direct uptake via the root hairs and root epidermis at the plant-soil interface, or indirectly through the AM fungal hyphae at the plant-fungus interface. Over the last few years, great progress has been made in deciphering the mechanisms underlying the AM-mediated modulation of nutrient uptake processes, and an increasing number of plant and fungal genes responsible for transporting nutrients from the soil or across the intraradical symbiotic interfaces have been identified and functionally characterized. Here, we summarize the recent advances in the nitrogen uptake, assimilation and translocation in the AM symbiosis, and also explore the current understanding of how the N status and interplay with C and P in modulating the development of AM associations. Copyright © 2017. Published by Elsevier Ltd.

Development and Symbiosis Establishment in the Cnidarian Endosymbiosis Model Aiptasia sp.

PubMed Central

Bucher, Madeline; Wolfowicz, Iliona; Voss, Philipp A.; Hambleton, Elizabeth A.; Guse, Annika

2016-01-01

Symbiosis between photosynthetic algae and heterotrophic organisms is widespread. One prominent example of high ecological relevance is the endosymbiosis between dinoflagellate algae of the genus Symbiodinium and reef-building corals, which typically acquire symbionts anew each generation during larval stages. The tropical sea anemone Aiptasia sp. is a laboratory model system for this endosymbiosis and, similar to corals, produces non-symbiotic larvae that establish symbiosis by phagocytosing Symbiodinium from the environment into the endoderm. Here we generate the first overview of Aiptasia embryogenesis and larval development and establish in situ hybridization to analyze expression patterns of key early developmental regulators. Next, we quantify morphological changes in developing larvae and find a substantial enlargement of the gastric cavity over time. Symbiont acquisition starts soon after mouth formation and symbionts occupy a major portion of the host cell in which they reside. During the first 14 days of development, infection efficiency remains constant while in contrast, localization of phagocytosed symbionts changes, indicating that the occurrence of functional phagocytosing cells may be developmentally regulated. Taken together, here we provide the essential framework to further develop Aiptasia as a model system for the analysis of symbiosis establishment in cnidarian larvae at the molecular level. PMID:26804034

Development and Symbiosis Establishment in the Cnidarian Endosymbiosis Model Aiptasia sp.

PubMed

Bucher, Madeline; Wolfowicz, Iliona; Voss, Philipp A; Hambleton, Elizabeth A; Guse, Annika

2016-01-25

Symbiosis between photosynthetic algae and heterotrophic organisms is widespread. One prominent example of high ecological relevance is the endosymbiosis between dinoflagellate algae of the genus Symbiodinium and reef-building corals, which typically acquire symbionts anew each generation during larval stages. The tropical sea anemone Aiptasia sp. is a laboratory model system for this endosymbiosis and, similar to corals, produces non-symbiotic larvae that establish symbiosis by phagocytosing Symbiodinium from the environment into the endoderm. Here we generate the first overview of Aiptasia embryogenesis and larval development and establish in situ hybridization to analyze expression patterns of key early developmental regulators. Next, we quantify morphological changes in developing larvae and find a substantial enlargement of the gastric cavity over time. Symbiont acquisition starts soon after mouth formation and symbionts occupy a major portion of the host cell in which they reside. During the first 14 days of development, infection efficiency remains constant while in contrast, localization of phagocytosed symbionts changes, indicating that the occurrence of functional phagocytosing cells may be developmentally regulated. Taken together, here we provide the essential framework to further develop Aiptasia as a model system for the analysis of symbiosis establishment in cnidarian larvae at the molecular level.

Lipid metabolic changes in an early divergent fungus govern the establishment of a mutualistic symbiosis with endobacteria

PubMed Central

Lastovetsky, Olga A.; Gaspar, Maria L.; Mondo, Stephen J.; LaButti, Kurt M.; Sandor, Laura; Grigoriev, Igor V.; Pawlowska, Teresa E.

2016-01-01

The recent accumulation of newly discovered fungal–bacterial mutualisms challenges the paradigm that fungi and bacteria are natural antagonists. To understand the mechanisms that govern the establishment and maintenance over evolutionary time of mutualisms between fungi and bacteria, we studied a symbiosis of the fungus Rhizopus microsporus (Mucoromycotina) and its Burkholderia endobacteria. We found that nonhost R. microsporus, as well as other mucoralean fungi, interact antagonistically with endobacteria derived from the host and are not invaded by them. Comparison of gene expression profiles of host and nonhost fungi during interaction with endobacteria revealed dramatic changes in expression of lipid metabolic genes in the host. Analysis of the host lipidome confirmed that symbiosis establishment was accompanied by specific changes in the fungal lipid profile. Diacylglycerol kinase (DGK) activity was important for these lipid metabolic changes, as its inhibition altered the fungal lipid profile and caused a shift in the host–bacterial interaction into an antagonism. We conclude that adjustments in host lipid metabolism during symbiosis establishment, mediated by DGKs, are required for the mutualistic outcome of the Rhizopus–Burkholderia symbiosis. In addition, the neutral and phospholipid profiles of R. microsporus provide important insights into lipid metabolism in an understudied group of oleaginous Mucoromycotina. Lastly, our study revealed that the DGKs involved in the symbiosis form a previously uncharacterized clade of DGK domain proteins. PMID:27956601

Lipid metabolic changes in an early divergent fungus govern the establishment of a mutualistic symbiosis with endobacteria.

PubMed

Lastovetsky, Olga A; Gaspar, Maria L; Mondo, Stephen J; LaButti, Kurt M; Sandor, Laura; Grigoriev, Igor V; Henry, Susan A; Pawlowska, Teresa E

2016-12-27

The recent accumulation of newly discovered fungal-bacterial mutualisms challenges the paradigm that fungi and bacteria are natural antagonists. To understand the mechanisms that govern the establishment and maintenance over evolutionary time of mutualisms between fungi and bacteria, we studied a symbiosis of the fungus Rhizopus microsporus (Mucoromycotina) and its Burkholderia endobacteria. We found that nonhost R. microsporus, as well as other mucoralean fungi, interact antagonistically with endobacteria derived from the host and are not invaded by them. Comparison of gene expression profiles of host and nonhost fungi during interaction with endobacteria revealed dramatic changes in expression of lipid metabolic genes in the host. Analysis of the host lipidome confirmed that symbiosis establishment was accompanied by specific changes in the fungal lipid profile. Diacylglycerol kinase (DGK) activity was important for these lipid metabolic changes, as its inhibition altered the fungal lipid profile and caused a shift in the host-bacterial interaction into an antagonism. We conclude that adjustments in host lipid metabolism during symbiosis establishment, mediated by DGKs, are required for the mutualistic outcome of the Rhizopus-Burkholderia symbiosis. In addition, the neutral and phospholipid profiles of R. microsporus provide important insights into lipid metabolism in an understudied group of oleaginous Mucoromycotina. Lastly, our study revealed that the DGKs involved in the symbiosis form a previously uncharacterized clade of DGK domain proteins.

Mycorrhizal symbiosis in leeks increases plant growth under low phosphorus and affects the levels of specific flavonoid glycosides

USDA-ARS?s Scientific Manuscript database

Introduction- Mycorrhizae symbiosis is a universal phenomenon in nature that promotes plant growth and food quality in most plants, especially, under phosphorus deficiency and water stress. Objective- The objective of this study was to assess the effects of mycorrhizal symbiosis on changes in the le...

Nonredundant Regulation of Rice Arbuscular Mycorrhizal Symbiosis by Two Members of the PHOSPHATE TRANSPORTER1 Gene Family[W

PubMed Central

Yang, Shu-Yi; Grønlund, Mette; Jakobsen, Iver; Grotemeyer, Marianne Suter; Rentsch, Doris; Miyao, Akio; Hirochika, Hirohiko; Kumar, Chellian Santhosh; Sundaresan, Venkatesan; Salamin, Nicolas; Catausan, Sheryl; Mattes, Nicolas; Heuer, Sigrid; Paszkowski, Uta

2012-01-01

Pi acquisition of crops via arbuscular mycorrhizal (AM) symbiosis is becoming increasingly important due to limited high-grade rock Pi reserves and a demand for environmentally sustainable agriculture. Here, we show that 70% of the overall Pi acquired by rice (Oryza sativa) is delivered via the symbiotic route. To better understand this pathway, we combined genetic, molecular, and physiological approaches to determine the specific functions of two symbiosis-specific members of the PHOSPHATE TRANSPORTER1 (PHT1) gene family from rice, ORYsa;PHT1;11 (PT11) and ORYsa;PHT1;13 (PT13). The PT11 lineage of proteins from mono- and dicotyledons is most closely related to homologs from the ancient moss, indicating an early evolutionary origin. By contrast, PT13 arose in the Poaceae, suggesting that grasses acquired a particular strategy for the acquisition of symbiotic Pi. Surprisingly, mutations in either PT11 or PT13 affected the development of the symbiosis, demonstrating that both genes are important for AM symbiosis. For symbiotic Pi uptake, however, only PT11 is necessary and sufficient. Consequently, our results demonstrate that mycorrhizal rice depends on the AM symbiosis to satisfy its Pi demands, which is mediated by a single functional Pi transporter, PT11. PMID:23073651

[From persistence to symbiosis of microorganisms].

PubMed

Bukharin, O V

2012-01-01

Primary results of study of problem of microorganism persistence over the last 2 decades on 7 all-Russian conferences in Orenburg are examined in the article. Milestones of both fundamental research and practically significant studies are designated, the role of persistent potential of microorganisms in infectious pathology is evaluated. The emerging turn of studies from persistence to symbiosis is consonant with the idea of international project "Human microbiom" and allows to use the persistent potential of microorganisms as one of the instruments of resolving issues of infectology.

Symbiosis between hydra and chlorella: molecular phylogenetic analysis and experimental study provide insight into its origin and evolution.

PubMed

Kawaida, Hitomi; Ohba, Kohki; Koutake, Yuhki; Shimizu, Hiroshi; Tachida, Hidenori; Kobayakawa, Yoshitaka

2013-03-01

Although many physiological studies have been reported on the symbiosis between hydra and green algae, very little information from a molecular phylogenetic aspect of symbiosis is available. In order to understand the origin and evolution of symbiosis between the two organisms, we compared the phylogenetic relationships among symbiotic green algae with the phylogenetic relationships among host hydra strains. To do so, we reconstructed molecular phylogenetic trees of several strains of symbiotic chlorella harbored in the endodermal epithelial cells of viridissima group hydra strains and investigated their congruence with the molecular phylogenetic trees of the host hydra strains. To examine the species specificity between the host and the symbiont with respect to the genetic distance, we also tried to introduce chlorella strains into two aposymbiotic strains of viridissima group hydra in which symbiotic chlorella had been eliminated in advance. We discussed the origin and history of symbiosis between hydra and green algae based on the analysis. Copyright © 2012 Elsevier Inc. All rights reserved.

Hydrogen peroxide-regulated genes in the Medicago truncatula-Sinorhizobium meliloti symbiosis.

PubMed

Andrio, Emilie; Marino, Daniel; Marmeys, Anthony; de Segonzac, Marion Dunoyer; Damiani, Isabelle; Genre, Andrea; Huguet, Stéphanie; Frendo, Pierre; Puppo, Alain; Pauly, Nicolas

2013-04-01

Reactive oxygen species (ROS), particularly hydrogen peroxide (H(2)O(2)), play an important role in signalling in various cellular processes. The involvement of H(2)O(2) in the Medicago truncatula-Sinorhizobium meliloti symbiotic interaction raises questions about its effect on gene expression. A transcriptome analysis was performed on inoculated roots of M. truncatula in which ROS production was inhibited with diphenylene iodonium (DPI). In total, 301 genes potentially regulated by ROS content were identified 2 d after inoculation. These genes included MtSpk1, which encodes a putative protein kinase and is induced by exogenous H(2)O(2) treatment. MtSpk1 gene expression was also induced by nodulation factor treatment. MtSpk1 transcription was observed in infected root hair cells, nodule primordia and the infection zone of mature nodules. Analysis with a fluorescent protein probe specific for H(2)O(2) showed that MtSpk1 expression and H(2)O(2) were similarly distributed in the nodule infection zone. Finally, the establishment of symbiosis was impaired by MtSpk1 downregulation with an artificial micro-RNA. Several genes regulated by H(2)O(2) during the establishment of rhizobial symbiosis were identified. The involvement of MtSpk1 in the establishment of the symbiosis is proposed. © 2013 The Authors. New Phytologist © 2013 New Phytologist Trust.

Evaluation of Project Symbiosis: An Interdisciplinary Science Education Project.

ERIC Educational Resources Information Center

Altschuld, James W.

1993-01-01

The goal of this report is to provide a summary of the evaluation of Project Symbiosis which focused on enhancing the teaching of science principles in high school agriculture courses. The project initially involved 15 teams of science and agriculture teachers and was characterized by an extensive evaluation component consisting of six formal…

Exploiting an ancient signalling machinery to enjoy a nitrogen fixing symbiosis.

PubMed

Geurts, Rene; Lillo, Alessandra; Bisseling, Ton

2012-08-01

For almost a century now it has been speculated that a transfer of the largely legume-specific symbiosis with nitrogen fixing rhizobium would be profitable in agriculture [1,2]. Up to now such a step has not been achieved, despite intensive research in this era. Novel insights in the underlying signalling networks leading to intracellular accommodation of rhizobium as well as mycorrhizal fungi of the Glomeromycota order show extensive commonalities between both interactions. As mycorrhizae symbiosis can be established basically with most higher plant species it raises questions why is it only in a few taxonomic lineages that the underlying signalling network could be hijacked by rhizobium. Unravelling this will lead to insights that are essential to achieve an old dream. Copyright © 2012. Published by Elsevier Ltd.

Forests trapped in nitrogen limitation--an ecological market perspective on ectomycorrhizal symbiosis.

PubMed

Franklin, Oskar; Näsholm, Torgny; Högberg, Peter; Högberg, Mona N

2014-07-01

Ectomycorrhizal symbiosis is omnipresent in boreal forests, where it is assumed to benefit plant growth. However, experiments show inconsistent benefits for plants and volatility of individual partnerships, which calls for a re-evaluation of the presumed role of this symbiosis. We reconcile these inconsistencies by developing a model that demonstrates how mycorrhizal networking and market mechanisms shape the strategies of individual plants and fungi to promote symbiotic stability at the ecosystem level. The model predicts that plants switch abruptly from a mixed strategy with both mycorrhizal and nonmycorrhizal roots to a purely mycorrhizal strategy as soil nitrogen availability declines, in agreement with the frequency distribution of ectomycorrhizal colonization intensity across a wide-ranging data set. In line with observations in field-scale isotope labeling experiments, the model explains why ectomycorrhizal symbiosis does not alleviate plant nitrogen limitation. Instead, market mechanisms may generate self-stabilization of the mycorrhizal strategy via nitrogen depletion feedback, even if plant growth is ultimately reduced. We suggest that this feedback mechanism maintains the strong nitrogen limitation ubiquitous in boreal forests. The mechanism may also have the capacity to eliminate or even reverse the expected positive effect of rising CO2 on tree growth in strongly nitrogen-limited boreal forests. © 2014 The Authors. New Phytologist © 2014 New Phytologist Trust.

Community analysis of microbial sharing and specialization in a Costa Rican ant-plant-hemipteran symbiosis.

PubMed

Pringle, Elizabeth G; Moreau, Corrie S

2017-03-15

Ants have long been renowned for their intimate mutualisms with trophobionts and plants and more recently appreciated for their widespread and diverse interactions with microbes. An open question in symbiosis research is the extent to which environmental influence, including the exchange of microbes between interacting macroorganisms, affects the composition and function of symbiotic microbial communities. Here we approached this question by investigating symbiosis within symbiosis. Ant-plant-hemipteran symbioses are hallmarks of tropical ecosystems that produce persistent close contact among the macroorganism partners, which then have substantial opportunity to exchange symbiotic microbes. We used metabarcoding and quantitative PCR to examine community structure of both bacteria and fungi in a Neotropical ant-plant-scale-insect symbiosis. Both phloem-feeding scale insects and honeydew-feeding ants make use of microbial symbionts to subsist on phloem-derived diets of suboptimal nutritional quality. Among the insects examined here, Cephalotes ants and pseudococcid scale insects had the most specialized bacterial symbionts, whereas Azteca ants appeared to consume or associate with more fungi than bacteria, and coccid scale insects were associated with unusually diverse bacterial communities. Despite these differences, we also identified apparent sharing of microbes among the macro-partners. How microbial exchanges affect the consumer-resource interactions that shape the evolution of ant-plant-hemipteran symbioses is an exciting question that awaits further research. © 2017 The Author(s).

Knowing your friends and foes--plant receptor-like kinases as initiators of symbiosis or defence.

PubMed

Antolín-Llovera, Meritxell; Petutsching, Elena Kristin; Ried, Martina Katharina; Lipka, Volker; Nürnberger, Thorsten; Robatzek, Silke; Parniske, Martin

2014-12-01

The decision between defence and symbiosis signalling in plants involves alternative and modular plasma membrane-localized receptor complexes. A critical step in their activation is ligand-induced homo- or hetero-oligomerization of leucine-rich repeat (LRR)- and/or lysin motif (LysM) receptor-like kinases (RLKs). In defence signalling, receptor complexes form upon binding of pathogen-associated molecular patterns (PAMPs), including the bacterial flagellin-derived peptide flg22, or chitin. Similar mechanisms are likely to operate during the perception of microbial symbiont-derived (lipo)-chitooligosaccharides. The structurally related chitin-oligomer ligands chitooctaose and chitotetraose trigger defence and symbiosis signalling, respectively, and their discrimination involves closely related, if not identical, LysM-RLKs. This illustrates the demand for and the challenges imposed on decision mechanisms that ensure appropriate signal initiation. Appropriate signalling critically depends on abundance and localization of RLKs at the cell surface. This is regulated by internalization, which also provides a mechanism for the removal of activated signalling RLKs. Abundance of the malectin-like domain (MLD)-LRR-RLK Symbiosis Receptor-like Kinase (SYMRK) is additionally controlled by cleavage of its modular ectodomain, which generates a truncated and rapidly degraded RLK fragment. This review explores LRR- and LysM-mediated signalling, the involvement of MLD-LRR-RLKs in symbiosis and defence, and the role of endocytosis in RLK function. © 2014 The Authors. New Phytologist © 2014 New Phytologist Trust.

Arbuscular mycorrhizal symbiosis induces strigolactone biosynthesis under drought and improves drought tolerance in lettuce and tomato.

PubMed

Ruiz-Lozano, Juan Manuel; Aroca, Ricardo; Zamarreño, Ángel María; Molina, Sonia; Andreo-Jiménez, Beatriz; Porcel, Rosa; García-Mina, José María; Ruyter-Spira, Carolien; López-Ráez, Juan Antonio

2016-02-01

Arbuscular mycorrhizal (AM) symbiosis alleviates drought stress in plants. However, the intimate mechanisms involved, as well as its effect on the production of signalling molecules associated with the host plant-AM fungus interaction remains largely unknown. In the present work, the effects of drought on lettuce and tomato plant performance and hormone levels were investigated in non-AM and AM plants. Three different water regimes were applied, and their effects were analysed over time. AM plants showed an improved growth rate and efficiency of photosystem II than non-AM plants under drought from very early stages of plant colonization. The levels of the phytohormone abscisic acid, as well as the expression of the corresponding marker genes, were influenced by drought stress in non-AM and AM plants. The levels of strigolactones and the expression of corresponding marker genes were affected by both AM symbiosis and drought. The results suggest that AM symbiosis alleviates drought stress by altering the hormonal profiles and affecting plant physiology in the host plant. In addition, a correlation between AM root colonization, strigolactone levels and drought severity is shown, suggesting that under these unfavourable conditions, plants might increase strigolactone production in order to promote symbiosis establishment to cope with the stress. © 2015 John Wiley & Sons Ltd.

Arbuscular mycorrhizal symbiosis and methyl jasmonate avoid the inhibition of root hydraulic conductivity caused by drought.

PubMed

Sánchez-Romera, Beatriz; Ruiz-Lozano, Juan Manuel; Zamarreño, Ángel María; García-Mina, José María; Aroca, Ricardo

2016-02-01

Hormonal regulation and symbiotic relationships provide benefits for plants to overcome stress conditions. The aim of this study was to elucidate the effects of exogenous methyl jasmonate (MeJA) application on root hydraulic conductivity (L) of Phaseolus vulgaris plants which established arbuscular mycorrhizal (AM) symbiosis under two water regimes (well-watered and drought conditions). The variation in endogenous contents of several hormones (MeJA, JA, abscisic acid (ABA), indol-3-acetic acid (IAA), salicylic acid (SA)) and the changes in aquaporin gene expression, protein abundance and phosphorylation state were analyzed. AM symbiosis decreased L under well-watered conditions, which was partially reverted by the MeJA treatment, apparently by a drop in root IAA contents. Also, AM symbiosis and MeJA prevented inhibition of L under drought conditions, most probably by a reduction in root SA contents. Additionally, the gene expression of two fungal aquaporins was upregulated under drought conditions, independently of the MeJA treatment. Plant aquaporin gene expression could not explain the behaviour of L. Conversely, evidence was found for the control of L by phosphorylation of aquaporins. Hence, MeJA addition modified the response of L to both AM symbiosis and drought, presumably by regulating the root contents of IAA and SA and the phosphorylation state of aquaporins.

Bark Beetle-Fungal Symbiosis: Context Dependency in Complex Associations

Treesearch

Kier D. Klepzig; D.L. Six

2004-01-01

Recent thinking in symbiosis research has emphasized a holistic consideration of these complex interactions. Bark beetles and their associated microbes are one group which has previously not been addressed in this manner. We review the study of symbiotic interactions among bark beetles and microbes in light of this thinking. We describe the considerable progress...

Insights into the history of the legume-betaproteobacterial symbiosis.

PubMed

Angus, Annette A; Hirsch, Ann M

2010-01-01

The interaction between legumes and rhizobia has been well studied in the context of a mutualistic, nitrogen-fixing symbiosis. The fitness of legumes, including important agricultural crops, is enhanced by the plants' ability to develop symbiotic associations with certain soil bacteria that fix atmospheric nitrogen into a utilizable form, namely, ammonia, via a chemical reaction that only bacteria and archaea can perform. Of the bacteria, members of the alpha subclass of the protebacteria are the best-known nitrogen-fixing symbionts of legumes. Recently, members of the beta subclass of the proteobacteria that induce nitrogen-fixing nodules on legume roots in a species-specific manner have been identified. In this issue, Bontemps et al. reveal that not only are these newly identified rhizobia novel in shifting the paradigm of our understanding of legume symbiosis, but also, based on symbiotic gene phylogenies, have a history that is both ancient and stable. Expanding our understanding of novel plant growth promoting rhizobia will be a valuable resource for incorporating alternative strategies of nitrogen fixation for enhancing plant growth.

Impact of simulated microgravity on the normal developmental time line of an animal-bacteria symbiosis

PubMed Central

Foster, Jamie S.; Khodadad, Christina L. M.; Ahrendt, Steven R.; Parrish, Mirina L.

2013-01-01

The microgravity environment during space flight imposes numerous adverse effects on animal and microbial physiology. It is unclear, however, how microgravity impacts those cellular interactions between mutualistic microbes and their hosts. Here, we used the symbiosis between the host squid Euprymna scolopes and its luminescent bacterium Vibrio fischeri as a model system. We examined the impact of simulated microgravity on the timeline of bacteria-induced development in the host light organ, the site of the symbiosis. To simulate the microgravity environment, host squid and symbiosis-competent bacteria were incubated together in high-aspect ratio rotating wall vessel bioreactors and examined throughout the early stages of the bacteria-induced morphogenesis. The host innate immune response was suppressed under simulated microgravity; however, there was an acceleration of bacteria-induced apoptosis and regression in the host tissues. These results suggest that the space flight environment may alter the cellular interactions between animal hosts and their natural healthy microbiome. PMID:23439280

Symbiosis-inspired approaches to antibiotic discovery.

PubMed

Adnani, Navid; Rajski, Scott R; Bugni, Tim S

2017-07-06

Covering: 2010 up to 2017Life on Earth is characterized by a remarkable abundance of symbiotic and highly refined relationships among life forms. Defined as any kind of close, long-term association between two organisms, symbioses can be mutualistic, commensalistic or parasitic. Historically speaking, selective pressures have shaped symbioses in which one organism (typically a bacterium or fungus) generates bioactive small molecules that impact the host (and possibly other symbionts); the symbiosis is driven fundamentally by the genetic machineries available to the small molecule producer. The human microbiome is now integral to the most recent chapter in animal-microbe symbiosis studies and plant-microbe symbioses have significantly advanced our understanding of natural products biosynthesis; this also is the case for studies of fungal-microbe symbioses. However, much less is known about microbe-microbe systems involving interspecies interactions. Microbe-derived small molecules (i.e. antibiotics and quorum sensing molecules, etc.) have been shown to regulate transcription in microbes within the same environmental niche, suggesting interspecies interactions whereas, intraspecies interactions, such as those that exploit autoinducing small molecules, also modulate gene expression based on environmental cues. We, and others, contend that symbioses provide almost unlimited opportunities for the discovery of new bioactive compounds whose activities and applications have been evolutionarily optimized. Particularly intriguing is the possibility that environmental effectors can guide laboratory expression of secondary metabolites from "orphan", or silent, biosynthetic gene clusters (BGCs). Notably, many of the studies summarized here result from advances in "omics" technologies and highlight how symbioses have given rise to new anti-bacterial and antifungal natural products now being discovered.

Neo-Symbiosis: The Next Stage in the Evolution of Human Information Interaction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Griffith, Douglas; Greitzer, Frank L.

Abstract--The purpose of this paper is to re-address the vision of human-computer symbiosis as originally expressed by J.C.R. Licklider nearly a half-century ago. We describe this vision, place it in some historical context relating to the evolution of human factors research, and we observe that the field is now in the process of re-invigorating Licklider’s vision. We briefly assess the state of the technology within the context of contemporary theory and practice, and we describe what we regard as this emerging field of neo-symbiosis. We offer some initial thoughts on requirements to define functionality of neo-symbiotic systems and discuss researchmore » challenges associated with their development and evaluation.« less

Insights on the Impact of Arbuscular Mycorrhizal Symbiosis on Tomato Tolerance to Water Stress.

PubMed

Chitarra, Walter; Pagliarani, Chiara; Maserti, Biancaelena; Lumini, Erica; Siciliano, Ilenia; Cascone, Pasquale; Schubert, Andrea; Gambino, Giorgio; Balestrini, Raffaella; Guerrieri, Emilio

2016-06-01

Arbuscular mycorrhizal (AM) fungi, which form symbioses with the roots of the most important crop species, are usually considered biofertilizers, whose exploitation could represent a promising avenue for the development in the future of a more sustainable next-generation agriculture. The best understood function in symbiosis is an improvement in plant mineral nutrient acquisition, as exchange for carbon compounds derived from the photosynthetic process: this can enhance host growth and tolerance to environmental stresses, such as water stress (WS). However, physiological and molecular mechanisms occurring in arbuscular mycorrhiza-colonized plants and directly involved in the mitigation of WS effects need to be further investigated. The main goal of this work is to verify the potential impact of AM symbiosis on the plant response to WS To this aim, the effect of two AM fungi (Funneliformis mosseae and Rhizophagus intraradices) on tomato (Solanum lycopersicum) under the WS condition was studied. A combined approach, involving ecophysiological, morphometric, biochemical, and molecular analyses, has been used to highlight the mechanisms involved in plant response to WS during AM symbiosis. Gene expression analyses focused on a set of target genes putatively involved in the plant response to drought, and in parallel, we considered the expression changes induced by the imposed stress on a group of fungal genes playing a key role in the water-transport process. Taken together, the results show that AM symbiosis positively affects the tolerance to WS in tomato, with a different plant response depending on the AM fungi species involved. © 2016 American Society of Plant Biologists. All Rights Reserved.

Large-scale label-free quantitative proteomics of the pea aphid-Buchnera symbiosis.

PubMed

Poliakov, Anton; Russell, Calum W; Ponnala, Lalit; Hoops, Harold J; Sun, Qi; Douglas, Angela E; van Wijk, Klaas J

2011-06-01

Many insects are nutritionally dependent on symbiotic microorganisms that have tiny genomes and are housed in specialized host cells called bacteriocytes. The obligate symbiosis between the pea aphid Acyrthosiphon pisum and the γ-proteobacterium Buchnera aphidicola (only 584 predicted proteins) is particularly amenable for molecular analysis because the genomes of both partners have been sequenced. To better define the symbiotic relationship between this aphid and Buchnera, we used large-scale, high accuracy tandem mass spectrometry (nanoLC-LTQ-Orbtrap) to identify aphid and Buchnera proteins in the whole aphid body, purified bacteriocytes, isolated Buchnera cells and the residual bacteriocyte fraction. More than 1900 aphid and 400 Buchnera proteins were identified. All enzymes in amino acid metabolism annotated in the Buchnera genome were detected, reflecting the high (68%) coverage of the proteome and supporting the core function of Buchnera in the aphid symbiosis. Transporters mediating the transport of predicted metabolites were present in the bacteriocyte. Label-free spectral counting combined with hierarchical clustering, allowed to define the quantitative distribution of a subset of these proteins across both symbiotic partners, yielding no evidence for the selective transfer of protein among the partners in either direction. This is the first quantitative proteome analysis of bacteriocyte symbiosis, providing a wealth of information about molecular function of both the host cell and bacterial symbiont.

Forests trapped in nitrogen limitation – an ecological market perspective on ectomycorrhizal symbiosis

PubMed Central

Franklin, Oskar; Näsholm, Torgny; Högberg, Peter; Högberg, Mona N

2014-01-01

Ectomycorrhizal symbiosis is omnipresent in boreal forests, where it is assumed to benefit plant growth. However, experiments show inconsistent benefits for plants and volatility of individual partnerships, which calls for a re-evaluation of the presumed role of this symbiosis. We reconcile these inconsistencies by developing a model that demonstrates how mycorrhizal networking and market mechanisms shape the strategies of individual plants and fungi to promote symbiotic stability at the ecosystem level. The model predicts that plants switch abruptly from a mixed strategy with both mycorrhizal and nonmycorrhizal roots to a purely mycorrhizal strategy as soil nitrogen availability declines, in agreement with the frequency distribution of ectomycorrhizal colonization intensity across a wide-ranging data set. In line with observations in field-scale isotope labeling experiments, the model explains why ectomycorrhizal symbiosis does not alleviate plant nitrogen limitation. Instead, market mechanisms may generate self-stabilization of the mycorrhizal strategy via nitrogen depletion feedback, even if plant growth is ultimately reduced. We suggest that this feedback mechanism maintains the strong nitrogen limitation ubiquitous in boreal forests. The mechanism may also have the capacity to eliminate or even reverse the expected positive effect of rising CO2 on tree growth in strongly nitrogen-limited boreal forests. PMID:24824576

Physiological and antioxidant responses of Medicago sativa-rhizobia symbiosis to cyanobacterial toxins (Microcystins) exposure.

PubMed

El Khalloufi, Fatima; Oufdou, Khalid; Lahrouni, Majida; Faghire, Mustapha; Peix, Alvaro; Ramírez-Bahena, Martha Helena; Vasconcelos, Vitor; Oudra, Brahim

2013-12-15

Toxic cyanobacteria in freshwaters can induce potent harmful effects on growth and development of plants irrigated with contaminated water. In this study, the effect of cyanobacteria extract containing Microcystins (MC) on Medicago sativa-rhizobia symbiosis was investigated in order to explore plants response through biomass production, photosynthetic pigment and antioxidant enzymes analysis: Peroxidase (POD), Polyphenoloxidase (PPO) and Catalase (CAT). Alfalfa plants were inoculated with two endosymbiotic rhizobial strains: RhOL1 (MC less sensitive strain) and RhOL3 (MC more sensitive strain), to evaluate the rhizobial contribution on the plant response cultured under cyanobacterial toxins stress. The two rhizobia strains were identified as Ensifer meliloti by sequence analysis of their rrs and atpD genes. The chronic exposure to MC extract showed shoot, root and nodules dry weight decrease, in both symbiosis cultures. The rate of decline in plants inoculated with RhOL3 was higher than that in symbiosis with RhOL1 mainly at 20 μg L(-1) of MC. Cyanotoxins also reduced photosynthetic pigment content and generated an oxidative stress observed at cellular level. POD, PPO and CAT activities were significantly increased in leaves, roots and nodules of alfalfa plants exposed to MC. These enzyme activities were higher in plants inoculated with RhOL3 especially when alfalfa plants were exposed to 20 μg L(-1) of MC. The present paper reports new scientific finding related to the behavior of rhizobia-M. sativa associations to MC (Microcystins) for later recommendation concerning the possible use of these symbiosis face to crops exposure to MC contaminated water irrigation. Copyright © 2013 Elsevier Ltd. All rights reserved.

Sinorhizobium meliloti requires a cobalamin-dependent ribonucleotide reductase for symbiosis with its plant host

PubMed Central

Taga, Michiko E.; Walker, Graham C.

2010-01-01

Vitamin B12 (cobalamin) is a critical cofactor for animals and protists, yet its biosynthesis is limited to prokaryotes. We previously showed that the symbiotic nitrogen-fixing alphaproteobacterium Sinorhizobium meliloti requires cobalamin to establish a symbiotic relationship with its plant host, Medicago sativa (alfalfa). Here, the specific requirement for cobalamin in the S. meliloti-alfalfa symbiosis was investigated. Of the three known cobalamin-dependent enzymes in S. meliloti, the methylmalonyl CoA mutase (BhbA) does not affect symbiosis whereas disruption of the metH gene encoding the cobalamin-dependent methionine synthase causes a significant defect in symbiosis. Expression of the cobalamin-independent methionine synthase MetE alleviates this symbiotic defect, indicating that the requirement for methionine synthesis does not reflect a need for the cobalamin-dependent enzyme. To investigate the function of the cobalamin-dependent ribonucleotide reductase (RNR) encoded by nrdJ, S. meliloti was engineered to express an Escherichia coli cobalamin-independent (Class Ia) RNR instead of nrdJ. This strain is severely defective in symbiosis. Electron micrographs show that these cells can penetrate alfalfa nodules but are unable to differentiate into nitrogen-fixing bacteroids and instead are lysed in the plant cytoplasm. Flow cytometry analysis indicates that these bacteria are largely unable to undergo endoreduplication. These phenotypes may be due to the inactivation of the Class Ia RNR by reactive oxygen species and/or inadequate oxygen availability in the nodule. These results show that the critical role of the cobalamin-dependent RNR for survival of S. meliloti in its plant host can account for the considerable resources that S. meliloti dedicates to cobalamin biosynthesis. PMID:20698752

Compatibility between Legumes and Rhizobia for the Establishment of a Successful Nitrogen-Fixing Symbiosis

PubMed Central

Clúa, Joaquín; Roda, Carla

2018-01-01

The root nodule symbiosis established between legumes and rhizobia is an exquisite biological interaction responsible for fixing a significant amount of nitrogen in terrestrial ecosystems. The success of this interaction depends on the recognition of the right partner by the plant within the richest microbial ecosystems on Earth, the soil. Recent metagenomic studies of the soil biome have revealed its complexity, which includes microorganisms that affect plant fitness and growth in a beneficial, harmful, or neutral manner. In this complex scenario, understanding the molecular mechanisms by which legumes recognize and discriminate rhizobia from pathogens, but also between distinct rhizobia species and strains that differ in their symbiotic performance, is a considerable challenge. In this work, we will review how plants are able to recognize and select symbiotic partners from a vast diversity of surrounding bacteria. We will also analyze recent advances that contribute to understand changes in plant gene expression associated with the outcome of the symbiotic interaction. These aspects of nitrogen-fixing symbiosis should contribute to translate the knowledge generated in basic laboratory research into biotechnological advances to improve the efficiency of the nitrogen-fixing symbiosis in agronomic systems. PMID:29495432

The impact of domestication and crop improvement on arbuscular mycorrhizal symbiosis in cereals: insights from genetics and genomics.

PubMed

Sawers, Ruairidh J H; Ramírez-Flores, M Rosario; Olalde-Portugal, Víctor; Paszkowski, Uta

2018-04-15

Contents Summary I. Introduction II. Recruitment of plant metabolites and hormones as signals in AM symbiosis III. Phytohormones are regulators of AM symbiosis and targets of plant breeding IV. Variations in host response to AM symbiosis V. Outlook Acknowledgements References SUMMARY: Cereals (rice, maize, wheat, sorghum and the millets) provide over 50% of the world's caloric intake, a value that rises to > 80% in developing countries. Since domestication, cereals have been under artificial selection, largely directed towards higher yield. Throughout this process, cereals have maintained their capacity to interact with arbuscular mycorrhizal (AM) fungi, beneficial symbionts that associate with the roots of most terrestrial plants. It has been hypothesized that the shift from the wild to cultivation, and above all the last c. 50 years of intensive breeding for high-input farming systems, has reduced the capacity of the major cereal crops to gain full benefit from AM interactions. Recent studies have shed further light on the molecular basis of establishment and functioning of AM symbiosis in cereals, providing insight into where the breeding process might have had an impact. Classic phytohormones, targets of artificial selection during the generation of Green Revolution semi-dwarf varieties, have emerged as important regulators of AM symbiosis. Although there is still much to be learnt about the mechanistic basis of variation in symbiotic outcome, these advances are providing an insight into the role of arbuscular mycorrhiza in agronomic systems. © 2018 The Authors. New Phytologist © 2018 New Phytologist Trust.

Selenium hyperaccumulation by Astragalus (Fabaceae) does not inhibit root nodule symbiosis.

PubMed

Alford, Elan R; Pilon-Smits, Elizabeth A H; Fakra, Sirine C; Paschke, Mark W

2012-12-01

A survey of the root-nodule symbiosis in Astragalus and its interaction with selenium (Se) has not been conducted before. Such studies can provide insight into how edaphic conditions modify symbiotic interactions and influence partner coevolution. In this paper plant-organ Se concentration ([Se]) was investigated to assess potential Se exposure to endophytes. • Selenium distribution and molecular speciation of root nodules from Se-hyperaccumulators Astragalus bisulcatus, A. praelongus, and A. racemosus was determined by Se K-edge x-ray absorption spectroscopy. A series of greenhouse experiments were conducted to characterize the response of root-nodule symbiosis in Se-hyperaccumulators and nonhyperaccumulators. • Nodules in three Se-hyperaccumulators (Astragalus crotalariae, A. praelongus, and A. preussii) are reported for the first time. Leaves, flowers, and fruits from Se-hyperaccumulators were routinely above the hyperaccumulator threshold (1,000 µg Se g(-1) DW), but root samples rarely contained that amount, and nodules never exceeded 110 µg Se g(-1) DW. Nodules from A. bisulcatus, A. praelongus, and A. racemosus had Se throughout, with a majority stored in C-Se-C form. Finally, an evaluation of nodulation in Se-hyperaccumulators and nonhyperaccumulators indicated that there was no nodulation inhibition because of plant Se tolerance. Rather, we found that in Se-hyperaccumulators higher levels of Se treatment (up to 100 µM Se) corresponded with higher nodule counts, indicating a potential role for dinitrogen fixation in Se-hyperaccumulation. The effect was not found in nonhyperaccumulators. • As the evolution of Se hyperaccumulation in Astragalus developed, root-nodule symbiosis may have played an integral role.

Genetics of mycorrhizal symbiosis in winter wheat (Triticum aestivum).

PubMed

Lehnert, Heike; Serfling, Albrecht; Enders, Matthias; Friedt, Wolfgang; Ordon, Frank

2017-07-01

Bread wheat (Triticum aestivum) is a major staple food and therefore of prime importance for feeding the Earth's growing population. Mycorrhiza is known to improve plant growth, but although extensive knowledge concerning the interaction between mycorrhizal fungi and plants is available, genotypic differences concerning the ability of wheat to form mycorrhizal symbiosis and quantitative trait loci (QTLs) involved in mycorrhization are largely unknown. Therefore, a diverse set of 94 bread wheat genotypes was evaluated with regard to root colonization by arbuscular mycorrhizal fungi. In order to identify genomic regions involved in mycorrhization, these genotypes were analyzed using the wheat 90k iSelect chip, resulting in 17 823 polymorphic mapped markers, which were used in a genome-wide association study. Significant genotypic differences (P < 0.0001) were detected in the ability to form symbiosis and 30 significant markers associated with root colonization, representing six QTL regions, were detected on chromosomes 3A, 4A and 7A, and candidate genes located in these QTL regions were proposed. The results reported here provide key insights into the genetics of root colonization by mycorrhizal fungi in wheat. © 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.

Symbiosis-Based Alternative Learning Multi-Swarm Particle Swarm Optimization.

PubMed

Niu, Ben; Huang, Huali; Tan, Lijing; Duan, Qiqi

2017-01-01

Inspired by the ideas from the mutual cooperation of symbiosis in natural ecosystem, this paper proposes a new variant of PSO, named Symbiosis-based Alternative Learning Multi-swarm Particle Swarm Optimization (SALMPSO). A learning probability to select one exemplar out of the center positions, the local best position, and the historical best position including the experience of internal and external multiple swarms, is used to keep the diversity of the population. Two different levels of social interaction within and between multiple swarms are proposed. In the search process, particles not only exchange social experience with others that are from their own sub-swarms, but also are influenced by the experience of particles from other fellow sub-swarms. According to the different exemplars and learning strategy, this model is instantiated as four variants of SALMPSO and a set of 15 test functions are conducted to compare with some variants of PSO including 10, 30 and 50 dimensions, respectively. Experimental results demonstrate that the alternative learning strategy in each SALMPSO version can exhibit better performance in terms of the convergence speed and optimal values on most multimodal functions in our simulation.

Expression patterns of sterol transporters NPC1 and NPC2 in the cnidarian-dinoflagellate symbiosis.

PubMed

Dani, Vincent; Priouzeau, Fabrice; Mertz, Marjolijn; Mondin, Magali; Pagnotta, Sophie; Lacas-Gervais, Sandra; Davy, Simon K; Sabourault, Cécile

2017-10-01

The symbiotic interaction between cnidarians (e.g., corals and sea anemones) and photosynthetic dinoflagellates of the genus Symbiodinium is triggered by both host-symbiont recognition processes and metabolic exchange between the 2 partners. The molecular communication is crucial for homeostatic regulation of the symbiosis, both under normal conditions and during stresses that further lead to symbiosis collapse. It is therefore important to identify and fully characterise the key players of this intimate interaction at the symbiotic interface. In this study, we determined the cellular and subcellular localization and expression of the sterol-trafficking Niemann-Pick type C proteins (NPC1 and NPC2) in the symbiotic sea anemones Anemonia viridis and Aiptasia sp. We first established that NPC1 is localised within vesicles in host tissues and to the symbiosome membranes in several anthozoan species. We demonstrated that the canonical NPC2-a protein is mainly expressed in the epidermis, whereas the NPC2-d protein is closely associated with symbiosome membranes. Furthermore, we showed that the expression of the NPC2-d protein is correlated with symbiont presence in healthy symbiotic specimens. As npc2-d is a cnidarian-specific duplicated gene, we hypothesised that it probably arose from a subfunctionalisation process that might result in a gain of function and symbiosis adaptation in anthozoans. Niemann-Pick type C proteins may be key players in a functional symbiosis and be useful tools to study host-symbiont interactions in the anthozoan-dinoflagellate association. © 2017 John Wiley & Sons Ltd.

Methanotrophic marine molluscan (Bivalvia, Mytilidae) symbiosis: mussels fueled by gas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Childress, J.J.; Fisher, C.R.; Brooks, J.M.

An undescribed mussel (family Mytilidae), which lives in the vicinity of hydrocarbon seeps in the Gulf of Mexico, consumes methane (the principal component of natural gas) at a high rate. The methane consumption is limited to the gills of these animals and is apparently due to the abundant intracellular bacteria found there. This demonstrates a methane-based symbiosis between an animal and intracellular bacteria. Methane consumption is dependent on the availability of oxygen and is inhibited by acetylene. The consumption of methane by these mussels is associated with a dramatic increase in oxygen consumption and carbon dioxide production. As the methanemore » consumption of the bivalve can exceed its carbide dioxide production, the symbiosis may be able to entirely satisfy its carbon needs from methane uptake. The very light (delta/sup 13/C = -51 to -57 per mil) stable carbon isotope ratios found in this animal support methane (delta/sup 13/C = -45 per mil at this site) as the primary carbon source for both the mussels and their symbionts. 19 references, 2 figures, 1 table.« less

The Mutual Symbiosis between Inclusive Bi-Lingual Education and Multicultural Education

ERIC Educational Resources Information Center

Irby, Beverly J.; Tong, Fuhui; Lara-Alecio, Rafael

2011-01-01

In this article the authors postulate a mutual symbiosis between multicultural and inclusive bi-lingual education. Combining bi-lingual and multicultural education to create a symbiotic relationship can stimulate reform in schools and can promote inclusive educational systems, thereby keeping native languages and cultures alive for minority…

Arbuscular Mycorrhizal Symbiosis Requires a Phosphate Transceptor in the Gigaspora margarita Fungal Symbiont.

PubMed

Xie, Xianan; Lin, Hui; Peng, Xiaowei; Xu, Congrui; Sun, Zhongfeng; Jiang, Kexin; Huang, Antian; Wu, Xiaohui; Tang, Nianwu; Salvioli, Alessandra; Bonfante, Paola; Zhao, Bin

2016-12-05

The majority of terrestrial vascular plants are capable of forming mutualistic associations with obligate biotrophic arbuscular mycorrhizal (AM) fungi from the phylum Glomeromycota. This mutualistic symbiosis provides carbohydrates to the fungus, and reciprocally improves plant phosphate uptake. AM fungal transporters can acquire phosphate from the soil through the hyphal networks. Nevertheless, the precise functions of AM fungal phosphate transporters, and whether they act as sensors or as nutrient transporters, in fungal signal transduction remain unclear. Here, we report a high-affinity phosphate transporter GigmPT from Gigaspora margarita that is required for AM symbiosis. Host-induced gene silencing of GigmPT hampers the development of G. margarita during AM symbiosis. Most importantly, GigmPT functions as a phosphate transceptor in G. margarita regarding the activation of the phosphate signaling pathway as well as the protein kinase A signaling cascade. Using the substituted-cysteine accessibility method, we identified residues A 146 (in transmembrane domain [TMD] IV) and Val 357 (in TMD VIII) of GigmPT, both of which are critical for phosphate signaling and transport in yeast during growth induction. Collectively, our results provide significant insights into the molecular functions of a phosphate transceptor from the AM fungus G. margarita. Copyright © 2016 The Author. Published by Elsevier Inc. All rights reserved.

A symbiosis-dedicated SYNTAXIN OF PLANTS 13II isoform controls the formation of a stable host-microbe interface in symbiosis.

PubMed

Huisman, Rik; Hontelez, Jan; Mysore, Kirankumar S; Wen, Jiangqi; Bisseling, Ton; Limpens, Erik

2016-09-01

Arbuscular mycorrhizal (AM) fungi and rhizobium bacteria are accommodated in specialized membrane compartments that form a host-microbe interface. To better understand how these interfaces are made, we studied the regulation of exocytosis during interface formation. We used a phylogenetic approach to identify target soluble N-ethylmaleimide-sensitive factor-attachment protein receptors (t-SNAREs) that are dedicated to symbiosis and used cell-specific expression analysis together with protein localization to identify t-SNAREs that are present on the host-microbe interface in Medicago truncatula. We investigated the role of these t-SNAREs during the formation of a host-microbe interface. We showed that multiple syntaxins are present on the peri-arbuscular membrane. From these, we identified SYNTAXIN OF PLANTS 13II (SYP13II) as a t-SNARE that is essential for the formation of a stable symbiotic interface in both AM and rhizobium symbiosis. In most dicot plants, the SYP13II transcript is alternatively spliced, resulting in two isoforms, SYP13IIα and SYP13IIβ. These splice-forms differentially mark functional and degrading arbuscule branches. Our results show that vesicle traffic to the symbiotic interface is specialized and required for its maintenance. Alternative splicing of SYP13II allows plants to replace a t-SNARE involved in traffic to the plasma membrane with a t-SNARE that is more stringent in its localization to functional arbuscules. © 2016 The Authors. New Phytologist © 2016 New Phytologist Trust.

Metabolic and physiological interdependencies in the Bathymodiolus azoricus symbiosis

PubMed Central

Ponnudurai, Ruby; Kleiner, Manuel; Sayavedra, Lizbeth; Petersen, Jillian M; Moche, Martin; Otto, Andreas; Becher, Dörte; Takeuchi, Takeshi; Satoh, Noriyuki; Dubilier, Nicole; Schweder, Thomas; Markert, Stephanie

2017-01-01

The hydrothermal vent mussel Bathymodiolus azoricus lives in an intimate symbiosis with two types of chemosynthetic Gammaproteobacteria in its gills: a sulfur oxidizer and a methane oxidizer. Despite numerous investigations over the last decades, the degree of interdependence between the three symbiotic partners, their individual metabolic contributions, as well as the mechanism of carbon transfer from the symbionts to the host are poorly understood. We used a combination of proteomics and genomics to investigate the physiology and metabolism of the individual symbiotic partners. Our study revealed that key metabolic functions are most likely accomplished jointly by B. azoricus and its symbionts: (1) CO2 is pre-concentrated by the host for carbon fixation by the sulfur-oxidizing symbiont, and (2) the host replenishes essential biosynthetic TCA cycle intermediates for the sulfur-oxidizing symbiont. In return (3), the sulfur oxidizer may compensate for the host's putative deficiency in amino acid and cofactor biosynthesis. We also identified numerous ‘symbiosis-specific' host proteins by comparing symbiont-containing and symbiont-free host tissues and symbiont fractions. These proteins included a large complement of host digestive enzymes in the gill that are likely involved in symbiont digestion and carbon transfer from the symbionts to the host. PMID:27801908

Metabolic and physiological interdependencies in the Bathymodiolus azoricus symbiosis.

PubMed

Ponnudurai, Ruby; Kleiner, Manuel; Sayavedra, Lizbeth; Petersen, Jillian M; Moche, Martin; Otto, Andreas; Becher, Dörte; Takeuchi, Takeshi; Satoh, Noriyuki; Dubilier, Nicole; Schweder, Thomas; Markert, Stephanie

2017-02-01

The hydrothermal vent mussel Bathymodiolus azoricus lives in an intimate symbiosis with two types of chemosynthetic Gammaproteobacteria in its gills: a sulfur oxidizer and a methane oxidizer. Despite numerous investigations over the last decades, the degree of interdependence between the three symbiotic partners, their individual metabolic contributions, as well as the mechanism of carbon transfer from the symbionts to the host are poorly understood. We used a combination of proteomics and genomics to investigate the physiology and metabolism of the individual symbiotic partners. Our study revealed that key metabolic functions are most likely accomplished jointly by B. azoricus and its symbionts: (1) CO 2 is pre-concentrated by the host for carbon fixation by the sulfur-oxidizing symbiont, and (2) the host replenishes essential biosynthetic TCA cycle intermediates for the sulfur-oxidizing symbiont. In return (3), the sulfur oxidizer may compensate for the host's putative deficiency in amino acid and cofactor biosynthesis. We also identified numerous 'symbiosis-specific' host proteins by comparing symbiont-containing and symbiont-free host tissues and symbiont fractions. These proteins included a large complement of host digestive enzymes in the gill that are likely involved in symbiont digestion and carbon transfer from the symbionts to the host.

Insights on the Impact of Arbuscular Mycorrhizal Symbiosis on Tomato Tolerance to Water Stress1[OPEN

PubMed Central

Siciliano, Ilenia

2016-01-01

Arbuscular mycorrhizal (AM) fungi, which form symbioses with the roots of the most important crop species, are usually considered biofertilizers, whose exploitation could represent a promising avenue for the development in the future of a more sustainable next-generation agriculture. The best understood function in symbiosis is an improvement in plant mineral nutrient acquisition, as exchange for carbon compounds derived from the photosynthetic process: this can enhance host growth and tolerance to environmental stresses, such as water stress (WS). However, physiological and molecular mechanisms occurring in arbuscular mycorrhiza-colonized plants and directly involved in the mitigation of WS effects need to be further investigated. The main goal of this work is to verify the potential impact of AM symbiosis on the plant response to WS. To this aim, the effect of two AM fungi (Funneliformis mosseae and Rhizophagus intraradices) on tomato (Solanum lycopersicum) under the WS condition was studied. A combined approach, involving ecophysiological, morphometric, biochemical, and molecular analyses, has been used to highlight the mechanisms involved in plant response to WS during AM symbiosis. Gene expression analyses focused on a set of target genes putatively involved in the plant response to drought, and in parallel, we considered the expression changes induced by the imposed stress on a group of fungal genes playing a key role in the water-transport process. Taken together, the results show that AM symbiosis positively affects the tolerance to WS in tomato, with a different plant response depending on the AM fungi species involved. PMID:27208301

Symbiosis induces widespread changes in the proteome of the model cnidarian Aiptasia.

PubMed

Oakley, Clinton A; Ameismeier, Michael F; Peng, Lifeng; Weis, Virginia M; Grossman, Arthur R; Davy, Simon K

2016-07-01

Coral reef ecosystems are metabolically founded on the mutualism between corals and photosynthetic dinoflagellates of the genus Symbiodinium. The glass anemone Aiptasia sp. has become a tractable model for this symbiosis, and recent advances in genetic information have enabled the use of mass spectrometry-based proteomics in this model. We utilized label-free liquid chromatography electrospray-ionization tandem mass spectrometry to analyze the effects of symbiosis on the proteomes of symbiotic and aposymbiotic Aiptasia. We identified and obtained relative quantification of more than 3,300 proteins in 1,578 protein clusters, with 81 protein clusters showing significantly different expression between symbiotic states. Symbiotic anemones showed significantly higher expression of proteins involved in lipid storage and transport, nitrogen transport and cycling, intracellular trafficking, endocytosis and inorganic carbon transport. These changes reflect shifts in host metabolism and nutrient reserves due to increased nutritional exchange with the symbionts, as well as mechanisms for supplying inorganic nutrients to the algae. Aposymbiotic anemones exhibited increased expression of multiple systems responsible for mediating reactive oxygen stress, suggesting that the host derives direct or indirect protection from oxidative stress while in symbiosis. Aposymbiotic anemones also increased their expression of an array of proteases and chitinases, indicating a metabolic shift from autotrophy to heterotrophy. These results provide a comprehensive Aiptasia proteome with more direct relative quantification of protein abundance than transcriptomic methods. The extension of "omics" techniques to this model system will allow more powerful studies of coral physiology, ecosystem function, and the effects of biotic and abiotic stress on the coral-dinoflagellate mutualism. © 2015 John Wiley & Sons Ltd.

The genome of Aiptasia, a sea anemone model for coral symbiosis

PubMed Central

Baumgarten, Sebastian; Simakov, Oleg; Esherick, Lisl Y.; Liew, Yi Jin; Lehnert, Erik M.; Michell, Craig T.; Li, Yong; Hambleton, Elizabeth A.; Guse, Annika; Oates, Matt E.; Gough, Julian; Weis, Virginia M.; Aranda, Manuel; Pringle, John R.; Voolstra, Christian R.

2015-01-01

The most diverse marine ecosystems, coral reefs, depend upon a functional symbiosis between a cnidarian animal host (the coral) and intracellular photosynthetic dinoflagellate algae. The molecular and cellular mechanisms underlying this endosymbiosis are not well understood, in part because of the difficulties of experimental work with corals. The small sea anemone Aiptasia provides a tractable laboratory model for investigating these mechanisms. Here we report on the assembly and analysis of the Aiptasia genome, which will provide a foundation for future studies and has revealed several features that may be key to understanding the evolution and function of the endosymbiosis. These features include genomic rearrangements and taxonomically restricted genes that may be functionally related to the symbiosis, aspects of host dependence on alga-derived nutrients, a novel and expanded cnidarian-specific family of putative pattern-recognition receptors that might be involved in the animal–algal interactions, and extensive lineage-specific horizontal gene transfer. Extensive integration of genes of prokaryotic origin, including genes for antimicrobial peptides, presumably reflects an intimate association of the animal–algal pair also with its prokaryotic microbiome. PMID:26324906

Experimental evidence of a symbiosis between red-cockaded woodpeckers and fungi.

PubMed

Jusino, Michelle A; Lindner, Daniel L; Banik, Mark T; Rose, Kevin R; Walters, Jeffrey R

2016-03-30

Primary cavity excavators, such as woodpeckers, are ecosystem engineers in many systems. Associations between cavity excavators and fungi have long been hypothesized to facilitate cavity excavation, but these relationships have not been experimentally verified. Fungi may help excavators by softening wood, while excavators may facilitate fungal dispersal. Here we demonstrate that excavators facilitate fungal dispersal and thus we report the first experimental evidence of a symbiosis between fungi and a cavity excavator, the red-cockaded woodpecker (RCW,Picoides borealis). Swab samples of birds showed that RCWs carry fungal communities similar to those found in their completed excavations. A 26-month field experiment using human-made aseptically drilled excavations in live trees, half of which were inaccessible to RCWs, demonstrated that RCWs directly alter fungal colonization and community composition. Experimental excavations that were accessible to RCWs contained fungal communities similar to natural RCW excavations, whereas inaccessible experimental excavations contained significantly different fungal communities. Our work demonstrates a complex symbiosis between cavity excavators and communities of fungi, with implications for forest ecology, wildlife management, and conservation. © 2016 The Author(s).

Use of carbon monoxide and hydrogen by a bacteria-animal symbiosis from seagrass sediments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kleiner, Manuel; Wentrup, Cecilia; Holler, Thomas

The gutless marine worm Olavius algarvensis lives in symbiosis with chemosynthetic bacteria that provide nutrition by fixing carbon dioxide (CO 2) into biomass using reduced sulfur compounds as energy sources. A recent metaproteomic analysis of the O. algarvensis symbiosis indicated that carbon monoxide (CO) and hydrogen (H 2) might also be used as energy sources. We provide direct evidence that the O. algarvensis symbiosis consumes CO and H 2. Single cell imaging using nanoscale secondary ion mass spectrometry revealed that one of the symbionts, the γ3-symbiont, uses the energy from CO oxidation to fix CO 2. Pore water analysis revealedmore » considerable in-situ concentrations of CO and H 2 in the O. algarvensis environment, Mediterranean seagrass sediments. Pore water H 2 concentrations (89-2147 nM) were up to two orders of magnitude higher than in seawater, and up to 36-fold higher than previously known from shallow-water marine sediments. Pore water CO concentrations (17-51 nM) were twice as high as in the overlying seawater (no literature data from other shallow-water sediments are available for comparison). Ex-situ incubation experiments showed that dead seagrass rhizomes produced large amounts of CO. Lastly, CO production from decaying plant material could thus be a significant energy source for microbial primary production in seagrass sediments.« less

Symbiont-driven sulfur crystal formation in a thiotrophic symbiosis from deep-sea hydrocarbon seeps

PubMed Central

Eichinger, Irmgard; Schmitz-Esser, Stephan; Schmid, Markus; Fisher, Charles R; Bright, Monika

2014-01-01

The siboglinid tubeworm Sclerolinum contortum symbiosis inhabits sulfidic sediments at deep-sea hydrocarbon seeps in the Gulf of Mexico. A single symbiont phylotype in the symbiont-housing organ is inferred from phylogenetic analyses of the 16S ribosomal ribonucleic acid (16S rRNA) gene and fluorescent in situ hybridization. The phylotype we studied here, and a previous study from an arctic hydrocarbon seep population, reveal identical 16S rRNA symbiont gene sequences. While sulfide is apparently the energy source for the symbionts (and ultimately the gutless host), both partners also have to cope with its toxicity. This study demonstrates abundant large sulfur crystals restricted to the trophosome area. Based on Raman microspectroscopy and energy dispersive X-ray analysis, these crystals have the same S8 sulfur configuration as the recently described small sulfur vesicles formed in the symbionts. The crystals reside adjacent to the symbionts in the trophosome. This suggests that their formation is either extra- or intracellular in symbionts. We propose that formation of these crystals provides both energy-storage compounds for the symbionts and serves the symbiosis by removing excess toxic sulfide from host tissues. This symbiont-mediated sulfide detoxification may have been crucial for the establishment of thiotrophic symbiosis and continues to remain an important function of the symbionts. PMID:24992535

Use of carbon monoxide and hydrogen by a bacteria-animal symbiosis from seagrass sediments

DOE PAGES

Kleiner, Manuel; Wentrup, Cecilia; Holler, Thomas; ...

2015-05-27

The gutless marine worm Olavius algarvensis lives in symbiosis with chemosynthetic bacteria that provide nutrition by fixing carbon dioxide (CO 2) into biomass using reduced sulfur compounds as energy sources. A recent metaproteomic analysis of the O. algarvensis symbiosis indicated that carbon monoxide (CO) and hydrogen (H 2) might also be used as energy sources. We provide direct evidence that the O. algarvensis symbiosis consumes CO and H 2. Single cell imaging using nanoscale secondary ion mass spectrometry revealed that one of the symbionts, the γ3-symbiont, uses the energy from CO oxidation to fix CO 2. Pore water analysis revealedmore » considerable in-situ concentrations of CO and H 2 in the O. algarvensis environment, Mediterranean seagrass sediments. Pore water H 2 concentrations (89-2147 nM) were up to two orders of magnitude higher than in seawater, and up to 36-fold higher than previously known from shallow-water marine sediments. Pore water CO concentrations (17-51 nM) were twice as high as in the overlying seawater (no literature data from other shallow-water sediments are available for comparison). Ex-situ incubation experiments showed that dead seagrass rhizomes produced large amounts of CO. Lastly, CO production from decaying plant material could thus be a significant energy source for microbial primary production in seagrass sediments.« less

Use of carbon monoxide and hydrogen by a bacteria–animal symbiosis from seagrass sediments

PubMed Central

Holler, Thomas; Lavik, Gaute; Harder, Jens; Lott, Christian; Littmann, Sten; Kuypers, Marcel M. M.; Dubilier, Nicole

2015-01-01

Summary The gutless marine worm O lavius algarvensis lives in symbiosis with chemosynthetic bacteria that provide nutrition by fixing carbon dioxide (CO 2) into biomass using reduced sulfur compounds as energy sources. A recent metaproteomic analysis of the O . algarvensis symbiosis indicated that carbon monoxide (CO) and hydrogen (H 2) might also be used as energy sources. We provide direct evidence that the O . algarvensis symbiosis consumes CO and H 2. Single cell imaging using nanoscale secondary ion mass spectrometry revealed that one of the symbionts, the γ3‐symbiont, uses the energy from CO oxidation to fix CO 2. Pore water analysis revealed considerable in‐situ concentrations of CO and H 2 in the O . algarvensis environment, Mediterranean seagrass sediments. Pore water H 2 concentrations (89–2147 nM) were up to two orders of magnitude higher than in seawater, and up to 36‐fold higher than previously known from shallow‐water marine sediments. Pore water CO concentrations (17–51 nM) were twice as high as in the overlying seawater (no literature data from other shallow‐water sediments are available for comparison). Ex‐situ incubation experiments showed that dead seagrass rhizomes produced large amounts of CO. CO production from decaying plant material could thus be a significant energy source for microbial primary production in seagrass sediments. PMID:26013766

Big Data Approaches To Coral-Microbe Symbiosis

NASA Astrophysics Data System (ADS)

Zaneveld, J.; Pollock, F. J.; McMinds, R.; Smith, S.; Payet, J.; Hanna, B.; Welsh, R.; Foster, A.; Ohdera, A.; Shantz, A. A.; Burkepile, D. E.; Maynard, J. A.; Medina, M.; Vega Thurber, R.

2016-02-01

Coral reefs face increasing challenges worldwide, threatened by overfishing and nutrient pollution, which drive growth of algal competitors of corals, and periods of extreme temperature, which drive mass coral bleaching. I will discuss two projects that examine how coral's complex relationships with microorganisms affect the response of coral colonies and coral species to environmental challenge. Microbiological studies have documented key roles for coral's microbial symbionts in energy harvest and defense against pathogens. However, the evolutionary history of corals and their microbes is little studied. As part of the Global Coral Microbiome Project, we are characterizing bacterial, archaeal, fungal, and Symbiodinium diversity across >1400 DNA samples from all major groups of corals, collected from 15 locations worldwide. This collection will allow us to ask how coral- microbe associations evolved over evolutionary time, and to determine whether microbial symbiosis helps predict the relative vulnerability of certain coral species to environmental stress. In the second project, we experimentally characterized how the long-term effects of human impacts such as overfishing and nutrient pollution influence coral-microbe symbiosis. We conducted a three-year field experiment in the Florida Keys applying nutrient pollution or simulated overfishing to reef plots, and traced the effects on reef communities, coral microbiomes, and coral health. The results show that extremes of temperature and algal competition destabilize coral microbiomes, increasing pathogen blooms, coral disease, and coral death. Surprisingly, these local stressors interacted strongly with thermal stress: the greatest microbiome disruption, and >80% of coral mortality happened in the hottest periods. Thus, overfishing and nutrient pollution may interact with increased climate-driven episodes of sub-bleaching thermal stress to increase coral mortality by disrupt reef communities down to microbial scales.

Nitric Oxide Mediates Biofilm Formation and Symbiosis in Silicibacter sp. Strain TrichCH4B.

PubMed

Rao, Minxi; Smith, Brian C; Marletta, Michael A

2015-05-05

Nitric oxide (NO) plays an important signaling role in all domains of life. Many bacteria contain a heme-nitric oxide/oxygen binding (H-NOX) protein that selectively binds NO. These H-NOX proteins often act as sensors that regulate histidine kinase (HK) activity, forming part of a bacterial two-component signaling system that also involves one or more response regulators. In several organisms, NO binding to the H-NOX protein governs bacterial biofilm formation; however, the source of NO exposure for these bacteria is unknown. In mammals, NO is generated by the enzyme nitric oxide synthase (NOS) and signals through binding the H-NOX domain of soluble guanylate cyclase. Recently, several bacterial NOS proteins have also been reported, but the corresponding bacteria do not also encode an H-NOX protein. Here, we report the first characterization of a bacterium that encodes both a NOS and H-NOX, thus resembling the mammalian system capable of both synthesizing and sensing NO. We characterized the NO signaling pathway of the marine alphaproteobacterium Silicibacter sp. strain TrichCH4B, determining that the NOS is activated by an algal symbiont, Trichodesmium erythraeum. NO signaling through a histidine kinase-response regulator two-component signaling pathway results in increased concentrations of cyclic diguanosine monophosphate, a key bacterial second messenger molecule that controls cellular adhesion and biofilm formation. Silicibacter sp. TrichCH4B biofilm formation, activated by T. erythraeum, may be an important mechanism for symbiosis between the two organisms, revealing that NO plays a previously unknown key role in bacterial communication and symbiosis. Bacterial nitric oxide (NO) signaling via heme-nitric oxide/oxygen binding (H-NOX) proteins regulates biofilm formation, playing an important role in protecting bacteria from oxidative stress and other environmental stresses. Biofilms are also an important part of symbiosis, allowing the organism to remain in a

An antimicrobial peptide essential for bacterial survival in the nitrogen-fixing symbiosis.

PubMed

Kim, Minsoo; Chen, Yuhui; Xi, Jiejun; Waters, Christopher; Chen, Rujin; Wang, Dong

2015-12-08

In the nitrogen-fixing symbiosis between legume hosts and rhizobia, the bacteria are engulfed by a plant cell membrane to become intracellular organelles. In the model legume Medicago truncatula, internalization and differentiation of Sinorhizobium (also known as Ensifer) meliloti is a prerequisite for nitrogen fixation. The host mechanisms that ensure the long-term survival of differentiating intracellular bacteria (bacteroids) in this unusual association are unclear. The M. truncatula defective nitrogen fixation4 (dnf4) mutant is unable to form a productive symbiosis, even though late symbiotic marker genes are expressed in mutant nodules. We discovered that in the dnf4 mutant, bacteroids can apparently differentiate, but they fail to persist within host cells in the process. We found that the DNF4 gene encodes NCR211, a member of the family of nodule-specific cysteine-rich (NCR) peptides. The phenotype of dnf4 suggests that NCR211 acts to promote the intracellular survival of differentiating bacteroids. The greatest expression of DNF4 was observed in the nodule interzone II-III, where bacteroids undergo differentiation. A translational fusion of DNF4 with GFP localizes to the peribacteroid space, and synthetic NCR211 prevents free-living S. meliloti from forming colonies, in contrast to mock controls, suggesting that DNF4 may interact with bacteroids directly or indirectly for its function. Our findings indicate that a successful symbiosis requires host effectors that not only induce bacterial differentiation, but also that maintain intracellular bacteroids during the host-symbiont interaction. The discovery of NCR211 peptides that maintain bacterial survival inside host cells has important implications for improving legume crops.

Value of the Hydra model system for studying symbiosis.

PubMed

Kovacevic, Goran

2012-01-01

Green Hydra is used as a classical example for explaining symbiosis in schools as well as an excellent research model. Indeed the cosmopolitan green Hydra (Hydra viridissima) provides a potent experimental framework to investigate the symbiotic relationships between a complex eumetazoan organism and a unicellular photoautotrophic green algae named Chlorella. Chlorella populates a single somatic cell type, the gastrodermal myoepithelial cells (also named digestive cells) and the oocyte at the time of sexual reproduction. This symbiotic relationship is stable, well-determined and provides biological advantages to the algal symbionts, but also to green Hydra over the related non-symbiotic Hydra i.e. brown hydra. These advantages likely result from the bidirectional flow of metabolites between the host and the symbiont. Moreover genetic flow through horizontal gene transfer might also participate in the establishment of these selective advantages. However, these relationships between the host and the symbionts may be more complex. Thus, Jolley and Smith showed that the reproductive rate of the algae increases dramatically outside of Hydra cells, although this endosymbiont isolation is debated. Recently it became possible to keep different species of endosymbionts isolated from green Hydra in stable and permanent cultures and compare them to free-living Chlorella species. Future studies testing metabolic relationships and genetic flow should help elucidate the mechanisms that support the maintenance of symbiosis in a eumetazoan species.

Identification of genes that regulate phosphate acquisition and plant performance during arbuscular my corrhizal symbiosis in medicago truncatula and brachypodium distachyon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Harrison, Maria J; Hudson, Matthew E

Most vascular flowering plants have the ability to form symbiotic associations with arbuscular mycorrhizal (AM) fungi. The symbiosis develops in the roots and can have a profound effect on plant productivity, largely through improvements in plant mineral nutrition. Within the root cortical cells, the plant and fungus create novel interfaces specialized for nutrient transfer, while the fungus also develops a network of hyphae in the rhizosphere. Through this hyphal network, the fungus acquires and delivers phosphate and nitrogen to the root. In return, the plant provides the fungus with carbon. In addition, to enhancing plant mineral nutrition, the AM symbiosismore » has an important role in the carbon cycle, and positive effects on soil health. Here we identified and characterized plant genes involved in the regulation and functioning of the AM symbiosis in Medicago truncatula and Brachypodium distachyon. This included the identification and and characterization of a M. truncatula transcription factors that are required for symbiosis. Additionally, we investigated the molecular basis of functional diversity among AM symbioses in B. distachyon and analysed the transcriptome of Brachypodium distachyon during symbiosis.« less

Arbuscular mycorrhizal symbiosis can mitigate the negative effects of night warming on physiological traits of Medicago truncatula L.

PubMed

Hu, Yajun; Wu, Songlin; Sun, Yuqing; Li, Tao; Zhang, Xin; Chen, Caiyan; Lin, Ge; Chen, Baodong

2015-02-01

Elevated night temperature, one of the main climate warming scenarios, can have profound effects on plant growth and metabolism. However, little attention has been paid to the potential role of mycorrhizal associations in plant responses to night warming, although it is well known that symbiotic fungi can protect host plants against various environmental stresses. In the present study, physiological traits of Medicago truncatula L. in association with the arbuscular mycorrhizal (AM) fungus Rhizophagus irregularis were investigated under simulated night warming. A constant increase in night temperature of 1.53 °C significantly reduced plant shoot and root biomass, flower and seed number, leaf sugar concentration, and shoot Zn and root P concentrations. However, the AM association essentially mitigated these negative effects of night warming by improving plant growth, especially through increased root biomass, root to shoot ratio, and shoot Zn and root P concentrations. A significant interaction was observed between R. irregularis inoculation and night warming in influencing both root sucrose concentration and expression of sucrose synthase (SusS) genes, suggesting that AM symbiosis and increased night temperature jointly regulated plant sugar metabolism. Night warming stimulated AM fungal colonization but did not influence arbuscule abundance, symbiosis-related plant or fungal gene expression, or growth of extraradical mycelium, indicating little effect of night warming on the development or functioning of AM symbiosis. These findings highlight the importance of mycorrhizal symbiosis in assisting plant resilience to climate warming.

Climate change promotes parasitism in a coral symbiosis.

PubMed

Baker, David M; Freeman, Christopher J; Wong, Jane C Y; Fogel, Marilyn L; Knowlton, Nancy

2018-03-01

Coastal oceans are increasingly eutrophic, warm and acidic through the addition of anthropogenic nitrogen and carbon, respectively. Among the most sensitive taxa to these changes are scleractinian corals, which engineer the most biodiverse ecosystems on Earth. Corals' sensitivity is a consequence of their evolutionary investment in symbiosis with the dinoflagellate alga, Symbiodinium. Together, the coral holobiont has dominated oligotrophic tropical marine habitats. However, warming destabilizes this association and reduces coral fitness. It has been theorized that, when reefs become warm and eutrophic, mutualistic Symbiodinium sequester more resources for their own growth, thus parasitizing their hosts of nutrition. Here, we tested the hypothesis that sub-bleaching temperature and excess nitrogen promotes symbiont parasitism by measuring respiration (costs) and the assimilation and translocation of both carbon (energy) and nitrogen (growth; both benefits) within Orbicella faveolata hosting one of two Symbiodinium phylotypes using a dual stable isotope tracer incubation at ambient (26 °C) and sub-bleaching (31 °C) temperatures under elevated nitrate. Warming to 31 °C reduced holobiont net primary productivity (NPP) by 60% due to increased respiration which decreased host %carbon by 15% with no apparent cost to the symbiont. Concurrently, Symbiodinium carbon and nitrogen assimilation increased by 14 and 32%, respectively while increasing their mitotic index by 15%, whereas hosts did not gain a proportional increase in translocated photosynthates. We conclude that the disparity in benefits and costs to both partners is evidence of symbiont parasitism in the coral symbiosis and has major implications for the resilience of coral reefs under threat of global change.

Trans-generational specificity within a cnidarian-algal symbiosis

NASA Astrophysics Data System (ADS)

Poland, D. M.; Coffroth, M. A.

2017-03-01

Ocean warming and other anthropogenic stresses threaten the symbiosis between tropical reef cnidarians and their dinoflagellate endosymbionts ( Symbiodinium). Offspring of many cnidarians acquire their algal symbionts from the environment, and such flexibility could allow corals to respond to environmental changes between generations. To investigate the effect of both habitat and host genotype on symbiont acquisition, we transplanted aposymbiotic offspring of the common Caribbean octocoral Briareum asbestinum to (1) an environmentally different habitat that lacked B. asbestinum and (2) an environmentally similar habitat where local adults harbored Symbiodinium phylotypes that differed from parental colonies. Symbiont acquisition and establishment of symbioses over time was followed using a within-clade DNA marker (23S chloroplast rDNA) and a within-phylotype marker (unique alleles at a single microsatellite locus). Early in the symbiosis, B. asbestinum juveniles harbored multiple symbiont phylotypes, regardless of source (parent or site). However, with time ( 4 yr), offspring established symbioses with the symbiont phylotype dominant in the parental colonies, regardless of transplant location. Within-phylotype analyses of the symbionts revealed a similar pattern, with offspring acquiring the allelic variant common in symbionts in the parental population regardless of the environment in which the offspring was reared. These data suggest that in this host species, host-symbiont specificity is a genetically determined trait. If this level of specificity is widespread among other symbiotic cnidarians, many cnidarian-algal symbioses may not be able to respond to rapid, climate change-associated environmental changes by means of between-generation switching of symbionts.

Understanding resilience in industrial symbiosis networks: insights from network analysis.

PubMed

Chopra, Shauhrat S; Khanna, Vikas

2014-08-01

Industrial symbiotic networks are based on the principles of ecological systems where waste equals food, to develop synergistic networks. For example, industrial symbiosis (IS) at Kalundborg, Denmark, creates an exchange network of waste, water, and energy among companies based on contractual dependency. Since most of the industrial symbiotic networks are based on ad-hoc opportunities rather than strategic planning, gaining insight into disruptive scenarios is pivotal for understanding the balance of resilience and sustainability and developing heuristics for designing resilient IS networks. The present work focuses on understanding resilience as an emergent property of an IS network via a network-based approach with application to the Kalundborg Industrial Symbiosis (KIS). Results from network metrics and simulated disruptive scenarios reveal Asnaes power plant as the most critical node in the system. We also observe a decrease in the vulnerability of nodes and reduction in single points of failure in the system, suggesting an increase in the overall resilience of the KIS system from 1960 to 2010. Based on our findings, we recommend design strategies, such as increasing diversity, redundancy, and multi-functionality to ensure flexibility and plasticity, to develop resilient and sustainable industrial symbiotic networks. Copyright © 2014 Elsevier Ltd. All rights reserved.

Convergent losses of decay mechanisms and rapid turnover of symbiosis genes in mycorrhizal mutualists

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kohler, Annegret; Kuo, Alan; Nagy, Laszlo G.

To elucidate the genetic bases of mycorrhizal lifestyle evolution, we sequenced new fungal genomes, including 13 ectomycorrhizal (ECM), orchid (ORM) and ericoid (ERM) species, and five saprotrophs, which we analyzed along with other fungal genomes. Ectomycorrhizal fungi have a reduced complement of genes encoding plant cell wall-degrading enzymes (PCWDEs), as compared to their ancestral wood decayers. Nevertheless, they have retained a unique array of PCWDEs, thus suggesting that they possess diverse abilities to decompose lignocellulose. Similar functional categories of nonorthologous genes are induced in symbiosis. Of induced genes, 7-38% are orphan genes, including genes that encode secreted effector-like proteins. Convergentmore » evolution of the mycorrhizal habit in fungi occurred via the repeated evolution of a 'symbiosis toolkit', with reduced numbers of PCWDEs and lineage-specific suites of mycorrhiza-induced genes.« less

Convergent losses of decay mechanisms and rapid turnover of symbiosis genes in mycorrhizal mutualists

DOE PAGES

Kohler, Annegret; Kuo, Alan; Nagy, Laszlo G.; ...

2015-02-23

To elucidate the genetic bases of mycorrhizal lifestyle evolution, we sequenced new fungal genomes, including 13 ectomycorrhizal (ECM), orchid (ORM) and ericoid (ERM) species, and five saprotrophs, which we analyzed along with other fungal genomes. Ectomycorrhizal fungi have a reduced complement of genes encoding plant cell wall-degrading enzymes (PCWDEs), as compared to their ancestral wood decayers. Nevertheless, they have retained a unique array of PCWDEs, thus suggesting that they possess diverse abilities to decompose lignocellulose. Similar functional categories of nonorthologous genes are induced in symbiosis. Of induced genes, 7-38% are orphan genes, including genes that encode secreted effector-like proteins. Convergentmore » evolution of the mycorrhizal habit in fungi occurred via the repeated evolution of a 'symbiosis toolkit', with reduced numbers of PCWDEs and lineage-specific suites of mycorrhiza-induced genes.« less

The Role of Plant Innate Immunity in the Legume-Rhizobium Symbiosis.

PubMed

Cao, Yangrong; Halane, Morgan K; Gassmann, Walter; Stacey, Gary

2017-04-28

A classic view of the evolution of mutualism is that it derives from a pathogenic relationship that attenuated over time to a situation in which both partners can benefit. If this is the case for rhizobia, then one might uncover features of the symbiosis that reflect this earlier pathogenic state. For example, as with plant pathogens, it is now generally assumed that rhizobia actively suppress the host immune response to allow infection and symbiosis establishment. Likewise, the host has retained mechanisms to control the nutrient supply to the symbionts and the number of nodules so that they do not become too burdensome. The open question is whether such events are strictly ancillary to the central symbiotic nodulation factor signaling pathway or are essential for rhizobial host infection. Subsequent to these early infection events, plant immune responses can also be induced inside nodules and likely play a role in, for example, nodule senescence. Thus, a balanced regulation of innate immunity is likely required throughout rhizobial infection, symbiotic establishment, and maintenance. In this review, we discuss the significance of plant immune responses in the regulation of symbiotic associations with rhizobia, as well as rhizobial evasion of the host immune system.

Common symbiosis genes CERBERUS and NSP1 provide additional insight into the establishment of arbuscular mycorrhizal and root nodule symbioses in Lotus japonicus.

PubMed

Nagae, Miwa; Takeda, Naoya; Kawaguchi, Masayoshi

2014-01-01

Arbuscular mycorrhizal symbiosis (AMS) and root nodule symbiosis (RNS) share several common symbiotic components, and many of the common symbiosis mutants block the entry of symbionts into the roots. We recently reported that CERBERUS (an E3 ubiquitin ligase) and NSP1 (a GRAS family transcription factor), required for RNS, also modulate AMS development in Lotus japonicus. The novel common symbiosis mutants, cerberus and nsp1, have low colonization of arbuscular mycorrhiza (AM) fungi, caused by a defect in internal hyphal elongation and by a decreased fungal entry into the roots, respectively. Here, we showed that CERBERUS was induced at the sites of symbiotic fungal or bacterial infection. NSP1 has been implicated in a strigolactone biosynthesis gene DWARF27 expression. Nevertheless, in nsp1, DWARF27 was induced by inoculation with AM fungi, implying the existence of a NSP1-independent regulatory mechanism of strigolactone biosynthesis during AMS establishment. These results support functional analysis of CERBERUS and NSP1, and also contribute to elucidation of common mechanisms in AMS and RNS.

Context Dependency of a Marine Defensive Symbiosis over a Wide Geographic Distribution

NASA Astrophysics Data System (ADS)

Lopanik, N.; Linneman, J.; Mathew, M.

2016-02-01

The invasive, temperate marine bryozoan Bugula neritina possesses an uncultured, vertically-transmitted bacterial symbiont that produces natural products known as bryostatins. These unpalatable polyketides protect the host larvae from predation. In the western Atlantic, two host genotypes were thought to be restricted to differing latitudes based on the presence of the defensive symbiont: undefended aposymbiotic Type N animals were found at high latitudes, while defended symbiotic Type S colonies were found at low latitudes, where predation pressure is higher. We found that the host genotypes are more widespread than previously thought, but that the symbiont appeared to be restricted to hosts at lower latitudes, regardless of host phylotype, leading to the question of what factors are involved in restricting the symbiont's range. We performed reciprocal transplant experiments of symbiotic and antibiotic-cured hosts, and measured host growth, a proxy for fitness. Our data indicate that possession of the symbiont appears to present a physiological cost to the host. This cost may be more pronounced at higher latitudes where the benefit of symbiosis is less apparent. In addition, preliminary evidence suggests that symbiont titer in a Type S colony from North Carolina transplanted to Virginia is reduced over a period of nearly 4 months. Taken together, these results suggest that a combination of factors may play a role in the distribution of the defensive symbiont: (i) hosts that possess the symbiont are outcompeted by aposymbiotic conspecifics at high latitude and reduced levels of predation pressure; and (ii) symbiont growth may be inhibited or sanctioned by the host at high latitudes. As defensive symbiosis is an important trait in marine habitats, understanding factors that affect the distribution of both the host and symbiont are necessary to fully appreciate the ecological impact of symbiosis.

Effects of nano-ZnO on the agronomically relevant Rhizobium-legume symbiosis

USDA-ARS?s Scientific Manuscript database

The impact of nano-ZnO (nZnO) on Rhizobium-legume symbiosis was studied with garden pea and its compatible bacterial partner Rhizobium leguminosarum bv. viciae 3841. Exposure of peas to nZnO had no impact on germination, but significantly affected root length. Chronic exposure of plant to nZnO impac...

Arbuscular Mycorrhizal Symbiosis with Arundo donax Decreases Root Respiration and Increases Both Photosynthesis and Plant Biomass Accumulation.

PubMed

Romero-Munar, Antònia; Del-Saz, Néstor Fernández; Ribas-Carbó, Miquel; Flexas, Jaume; Baraza, Elena; Florez-Sarasa, Igor; Fernie, Alisdair Robert; Gulías, Javier

2017-07-01

The effect of arbuscular mycorrhiza (AM) symbiosis on plant growth is associated with the balance between costs and benefits. A feedback regulation loop has been described in which the higher carbohydrate cost to plants for AM symbiosis is compensated by increases in their photosynthetic rates. Nevertheless, plant carbon balance depends both on photosynthetic carbon uptake and respiratory carbon consumption. The hypothesis behind this research was that the role of respiration in plant growth under AM symbiosis may be as important as that of photosynthesis. This hypothesis was tested in Arundo donax L. plantlets inoculated with Rhizophagus irregularis and Funneliformis mosseae. We tested the effects of AM inoculation on both photosynthetic capacity and in vivo leaf and root respiration. Additionally, analyses of the primary metabolism and ion content were performed in both leaves and roots. AM inoculation increased photosynthesis through increased CO 2 diffusion and electron transport in the chloroplast. Moreover, respiration decreased only in AM roots via the cytochrome oxidase pathway (COP) as measured by the oxygen isotope technique. This decline in the COP can be related to the reduced respiratory metabolism and substrates (sugars and tricarboxylic acid cycle intermediates) observed in roots. © 2017 John Wiley & Sons Ltd.

Metabolic Complementarity and Genomics of the Dual Bacterial Symbiosis of Sharpshooters

PubMed Central

Wu, Dongying; Daugherty, Sean C; Van Aken, Susan E; Pai, Grace H; Watkins, Kisha L; Khouri, Hoda; Tallon, Luke J; Zaborsky, Jennifer M; Dunbar, Helen E; Tran, Phat L; Moran, Nancy A

2006-01-01

Mutualistic intracellular symbiosis between bacteria and insects is a widespread phenomenon that has contributed to the global success of insects. The symbionts, by provisioning nutrients lacking from diets, allow various insects to occupy or dominate ecological niches that might otherwise be unavailable. One such insect is the glassy-winged sharpshooter (Homalodisca coagulata), which feeds on xylem fluid, a diet exceptionally poor in organic nutrients. Phylogenetic studies based on rRNA have shown two types of bacterial symbionts to be coevolving with sharpshooters: the gamma-proteobacterium Baumannia cicadellinicola and the Bacteroidetes species Sulcia muelleri. We report here the sequencing and analysis of the 686,192–base pair genome of B. cicadellinicola and approximately 150 kilobase pairs of the small genome of S. muelleri, both isolated from H. coagulata. Our study, which to our knowledge is the first genomic analysis of an obligate symbiosis involving multiple partners, suggests striking complementarity in the biosynthetic capabilities of the two symbionts: B. cicadellinicola devotes a substantial portion of its genome to the biosynthesis of vitamins and cofactors required by animals and lacks most amino acid biosynthetic pathways, whereas S. muelleri apparently produces most or all of the essential amino acids needed by its host. This finding, along with other results of our genome analysis, suggests the existence of metabolic codependency among the two unrelated endosymbionts and their insect host. This dual symbiosis provides a model case for studying correlated genome evolution and genome reduction involving multiple organisms in an intimate, obligate mutualistic relationship. In addition, our analysis provides insight for the first time into the differences in symbionts between insects (e.g., aphids) that feed on phloem versus those like H. coagulata that feed on xylem. Finally, the genomes of these two symbionts provide potential targets for

Bellagio conference and book. Symbiosis as Source of Evolutionary Innovation: Speciation and Morphogenesis. Conference--June 25-30, 1989, Bellagio Conference Center, Italy

NASA Technical Reports Server (NTRS)

Margulis, L.; Fester, R.

1991-01-01

This conference at the Bellagio Conference Center, Italy, from June 25-30, 1989, provided a unique opportunity for evolutionary theorists and symbiosis biologists to cross the boundaries of their respective disciplines and share ideas. A major task was to address the adequacy of the prevailing neodarwinian concept of evolution with respect to the relative importance of symbiosis in the origin of morphological and evolutionary novelty.

Evaluation of the Role of the LysM Receptor-Like Kinase, OsNFR5/OsRLK2 for AM Symbiosis in Rice.

PubMed

Miyata, Kana; Hayafune, Masahiro; Kobae, Yoshihiro; Kaku, Hanae; Nishizawa, Yoko; Masuda, Yoshiki; Shibuya, Naoto; Nakagawa, Tomomi

2016-11-01

In legume-specific rhizobial symbiosis, host plants perceive rhizobial signal molecules, Nod factors, by a pair of LysM receptor-like kinases, NFR1/LYK3 and NFR5/NFP, and activate symbiotic responses through the downstream signaling components also required for arbuscular mycorrhizal (AM) symbiosis. Recently, the rice NFR1/LYK3 ortholog, OsCERK1, was shown to play crucial roles for AM symbiosis. On the other hand, the roles of the NFR5/NFP ortholog in rice have not been elucidated, while it has been shown that NFR5/NFP orthologs, Parasponia PaNFR5 and tomato SlRLK10, engage in AM symbiosis. OsCERK1 also triggers immune responses in combination with a receptor partner, OsCEBiP, against fungal or bacterial infection, thus regulating opposite responses against symbiotic and pathogenic microbes. However, it has not been elucidated how OsCERK1 switches these opposite functions. Here, we analyzed the function of the rice NFR5/NFP ortholog, OsNFR5/OsRLK2, as a possible candidate of the OsCERK1 partner for symbiotic signaling. Inoculation of AM fungi induced the expression of OsNFR5 in the rice root, and the chimeric receptor consisting of the extracellular domain of LjNFR5 and the intracellular domain of OsNFR5 complemented the Ljnfr5 mutant for rhizobial symbiosis, indicating that the intracellular kinase domain of OsNFR5 could activate symbiotic signaling in Lotus japonicus. Although these data suggested the possible involvement of OsNFR5 in AM symbiosis, osnfr5 knockout mutants were colonized by AM fungi similar to the wild-type rice. These observations suggested several possibilities including the presence of functionally redundant genes other than OsNFR5 or involvement of novel ligands, which do not require OsNFR5 for recognition. © The Author 2016. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Quantitative evaluation of protocorm growth and fungal colonization in Bletilla striata (Orchidaceae) reveals less-productive symbiosis with a non-native symbiotic fungus.

PubMed

Yamamoto, Tatsuki; Miura, Chihiro; Fuji, Masako; Nagata, Shotaro; Otani, Yuria; Yagame, Takahiro; Yamato, Masahide; Kaminaka, Hironori

2017-02-21

In nature, orchid plants depend completely on symbiotic fungi for their nutrition at the germination and the subsequent seedling (protocorm) stages. However, only limited quantitative methods for evaluating the orchid-fungus interactions at the protocorm stage are currently available, which greatly constrains our understanding of the symbiosis. Here, we aimed to improve and integrate quantitative evaluations of the growth and fungal colonization in the protocorms of a terrestrial orchid, Blettila striata, growing on a plate medium. We achieved both symbiotic and asymbiotic germinations for the terrestrial orchid B. striata. The protocorms produced by the two germination methods grew almost synchronously for the first three weeks. At week four, however, the length was significantly lower in the symbiotic protocorms. Interestingly, the dry weight of symbiotic protocorms did not significantly change during the growth period, which implies that there was only limited transfer of carbon compounds from the fungus to the protocorms in this relationship. Next, to evaluate the orchid-fungus interactions, we developed an ink-staining method to observe the hyphal coils in protocorms without preparing thin sections. Crushing the protocorm under the coverglass enables us to observe all hyphal coils in the protocorms with high resolution. For this observation, we established a criterion to categorize the stages of hyphal coils, depending on development and degradation. By counting the symbiotic cells within each stage, it was possible to quantitatively evaluate the orchid-fungus symbiosis. We describe a method for quantitative evaluation of orchid-fungus symbiosis by integrating the measurements of plant growth and fungal colonization. The current study revealed that although fungal colonization was observed in the symbiotic protocorms, the weight of the protocorm did not significantly increase, which is probably due to the incompatibility of the fungus in this symbiosis. These

Effects of nano-TiO2 on the agronomically-relevant Rhizobium-legume symbiosis

USDA-ARS?s Scientific Manuscript database

The impact of nano-TiO2 on Rhizobium-legume symbiosis was studied using garden peas and the compatible bacterial partner Rhizobium leguminosarum bv. viciae 3841. Exposure to nano-TiO2 did not affect the germination of peas grown aseptically, nor did it impact the gross root structure. However, nano-...

Burkholderia bacteria infectiously induce the proto-farming symbiosis of Dictyostelium amoebae and food bacteria

PubMed Central

DiSalvo, Susanne; Haselkorn, Tamara S.; Bashir, Usman; Jimenez, Daniela; Brock, Debra A.; Queller, David C.; Strassmann, Joan E.

2015-01-01

Symbiotic associations can allow an organism to acquire novel traits by accessing the genetic repertoire of its partner. In the Dictyostelium discoideum farming symbiosis, certain amoebas (termed “farmers”) stably associate with bacterial partners. Farmers can suffer a reproductive cost but also gain beneficial capabilities, such as carriage of bacterial food (proto-farming) and defense against competitors. Farming status previously has been attributed to amoeba genotype, but the role of bacterial partners in its induction has not been examined. Here, we explore the role of bacterial associates in the initiation, maintenance, and phenotypic effects of the farming symbiosis. We demonstrate that two clades of farmer-associated Burkholderia isolates colonize D. discoideum nonfarmers and infectiously endow them with farmer-like characteristics, indicating that Burkholderia symbionts are a major driver of the farming phenomenon. Under food-rich conditions, Burkholderia-colonized amoebas produce fewer spores than uncolonized counterparts, with the severity of this reduction being dependent on the Burkholderia colonizer. However, the induction of food carriage by Burkholderia colonization may be considered a conditionally adaptive trait because it can confer an advantage to the amoeba host when grown in food-limiting conditions. We observed Burkholderia inside and outside colonized D. discoideum spores after fruiting body formation; this observation, together with the ability of Burkholderia to colonize new amoebas, suggests a mixed mode of symbiont transmission. These results change our understanding of the D. discoideum farming symbiosis by establishing that the bacterial partner, Burkholderia, is an important causative agent of the farming phenomenon. PMID:26305954

Burkholderia bacteria infectiously induce the proto-farming symbiosis of Dictyostelium amoebae and food bacteria.

PubMed

DiSalvo, Susanne; Haselkorn, Tamara S; Bashir, Usman; Jimenez, Daniela; Brock, Debra A; Queller, David C; Strassmann, Joan E

2015-09-08

Symbiotic associations can allow an organism to acquire novel traits by accessing the genetic repertoire of its partner. In the Dictyostelium discoideum farming symbiosis, certain amoebas (termed "farmers") stably associate with bacterial partners. Farmers can suffer a reproductive cost but also gain beneficial capabilities, such as carriage of bacterial food (proto-farming) and defense against competitors. Farming status previously has been attributed to amoeba genotype, but the role of bacterial partners in its induction has not been examined. Here, we explore the role of bacterial associates in the initiation, maintenance, and phenotypic effects of the farming symbiosis. We demonstrate that two clades of farmer-associated Burkholderia isolates colonize D. discoideum nonfarmers and infectiously endow them with farmer-like characteristics, indicating that Burkholderia symbionts are a major driver of the farming phenomenon. Under food-rich conditions, Burkholderia-colonized amoebas produce fewer spores than uncolonized counterparts, with the severity of this reduction being dependent on the Burkholderia colonizer. However, the induction of food carriage by Burkholderia colonization may be considered a conditionally adaptive trait because it can confer an advantage to the amoeba host when grown in food-limiting conditions. We observed Burkholderia inside and outside colonized D. discoideum spores after fruiting body formation; this observation, together with the ability of Burkholderia to colonize new amoebas, suggests a mixed mode of symbiont transmission. These results change our understanding of the D. discoideum farming symbiosis by establishing that the bacterial partner, Burkholderia, is an important causative agent of the farming phenomenon.

The membrane proteome of Medicago truncatula roots displays qualitative and quantitative changes in response to arbuscular mycorrhizal symbiosis.

PubMed

Abdallah, Cosette; Valot, Benoit; Guillier, Christelle; Mounier, Arnaud; Balliau, Thierry; Zivy, Michel; van Tuinen, Diederik; Renaut, Jenny; Wipf, Daniel; Dumas-Gaudot, Eliane; Recorbet, Ghislaine

2014-08-28

Arbuscular mycorrhizal (AM) symbiosis that associates roots of most land plants with soil-borne fungi (Glomeromycota), is characterized by reciprocal nutritional benefits. Fungal colonization of plant roots induces massive changes in cortical cells where the fungus differentiates an arbuscule, which drives proliferation of the plasma membrane. Despite the recognized importance of membrane proteins in sustaining AM symbiosis, the root microsomal proteome elicited upon mycorrhiza still remains to be explored. In this study, we first examined the qualitative composition of the root membrane proteome of Medicago truncatula after microsome enrichment and subsequent in depth analysis by GeLC-MS/MS. The results obtained highlighted the identification of 1226 root membrane protein candidates whose cellular and functional classifications predispose plastids and protein synthesis as prevalent organelle and function, respectively. Changes at the protein abundance level between the membrane proteomes of mycorrhizal and nonmycorrhizal roots were further monitored by spectral counting, which retrieved a total of 96 proteins that displayed a differential accumulation upon AM symbiosis. Besides the canonical markers of the periarbuscular membrane, new candidates supporting the importance of membrane trafficking events during mycorrhiza establishment/functioning were identified, including flotillin-like proteins. The data have been deposited to the ProteomeXchange with identifier PXD000875. During arbuscular mycorrhizal symbiosis, one of the most widespread mutualistic associations in nature, the endomembrane system of plant roots is believed to undergo qualitative and quantitative changes in order to sustain both the accommodation process of the AM fungus within cortical cells and the exchange of nutrients between symbionts. Large-scale GeLC-MS/MS proteomic analysis of the membrane fractions from mycorrhizal and nonmycorrhizal roots of M. truncatula coupled to spectral counting

The Medicago truncatula GRAS protein RAD1 supports arbuscular mycorrhiza symbiosis and Phytophthora palmivora susceptibility.

PubMed

Rey, Thomas; Bonhomme, Maxime; Chatterjee, Abhishek; Gavrin, Aleksandr; Toulotte, Justine; Yang, Weibing; André, Olivier; Jacquet, Christophe; Schornack, Sebastian

2017-12-16

The roots of most land plants are colonized by symbiotic arbuscular mycorrhiza (AM) fungi. To facilitate this symbiosis, plant genomes encode a set of genes required for microbial perception and accommodation. However, the extent to which infection by filamentous root pathogens also relies on some of these genes remains an open question. Here, we used genome-wide association mapping to identify genes contributing to colonization of Medicago truncatula roots by the pathogenic oomycete Phytophthora palmivora. Single-nucleotide polymorphism (SNP) markers most significantly associated with plant colonization response were identified upstream of RAD1, which encodes a GRAS transcription regulator first negatively implicated in root nodule symbiosis and recently identified as a positive regulator of AM symbiosis. RAD1 transcript levels are up-regulated both in response to AM fungus and, to a lower extent, in infected tissues by P. palmivora where its expression is restricted to root cortex cells proximal to pathogen hyphae. Reverse genetics showed that reduction of RAD1 transcript levels as well as a rad1 mutant are impaired in their full colonization by AM fungi as well as by P. palmivora. Thus, the importance of RAD1 extends beyond symbiotic interactions, suggesting a general involvement in M. truncatula microbe-induced root development and interactions with unrelated beneficial and detrimental filamentous microbes. © The Author 2017. Published by Oxford University Press on behalf of the Society for Experimental Biology.

Growth and flagellation of Vibrio fischeri during initiation of the sepiolid squid light organ symbiosis.

PubMed

Ruby, E G; Asato, L M

1993-01-01

A pure culture of the luminous bacterium Vibrio fischeri is maintained in the light-emitting organ of the sepiolid squid Euprymna scolopes. When the juvenile squid emerges from its egg it is symbiont-free and, because bioluminescence is part of an anti-predatory behavior, therefore must obtain a bacterial inoculum from the surrounding environment. We document here the kinetics of the process by which newly hatched juvenile squids become infected by symbiosis-competent V. fischeri. When placed in seawater containing as few as 240 colony-forming-units (CFU) per ml, the juvenile became detectably bioluminescent within a few hours. Colonization of the nascent light organ was initiated with as few as 1 to 10 bacteria, which rapidly began to grow at an exponential rate until they reached a population size of approximately 10(5) cells by 12 h after the initial infection. Subsequently, the number of bacteria in the established symbiosis was maintained essentially constant by a combination of both a > 20-fold reduction in bacterial growth rate, and an expulsion of excess bacteria into the surrounding seawater. While V. fischeri cells are normally flagellated and motile, these bacteria did not elaborate these appendages once the symbiosis was established; however, they quickly began to synthesize flagella when they were removed from the light organ environment. Thus, two important biological characteristics, growth rate and flagellation, were modulated during establishment of the association, perhaps as part of a coordinated series of symbiotic responses.

Breaking up and getting together: evolution of symbiosis and cloning by fission in sea anemones (Genus Anthopleura).

PubMed

Geller, J B; Walton, E D

2001-09-01

Clonal growth and symbiosis with photosynthetic zooxanthellae typify many genera of marine organisms, suggesting that these traits are usually conserved. However, some, such as Anthopleura, a genus of sea anemones, contain members lacking one or both of these traits. The evolutionary origins of these traits in 13 species of Anthopleura were inferred from a molecular phylogeny derived from 395 bp of the mitochondrial 16S rRNA gene and 410 bp of the mitochondrial cytochrome oxidase subunit III gene. Sequences from these genes were combined and analyzed by maximum-parsimony, maximum-likelihood, and neighbor-joining methods. Best trees from each method indicated a minimum of four changes in growth mode and that symbiosis with zooxanthellae has arisen independently in eastern and western Pacific species. Alternative trees in which species sharing growth modes or the symbiotic condition were constrained to be monophyletic were significantly worse than best trees. Although clade composition was mostly consistent with geographic sympatry, A. artemisia from California was included in the western Pacific clade. Likewise, A. midori from Japan was not placed in a clade containing only other Asian congeners. The history of Anthopleura includes repeated shifts between clonality and solitariness, repeated attainment of symbiosis with zooxanthellae, and intercontinental dispersal.

SYMBIOSIS: development, implementation, and assessment of a model curriculum across biology and mathematics at the introductory level.

PubMed

Depelteau, Audrey M; Joplin, Karl H; Govett, Aimee; Miller, Hugh A; Seier, Edith

2010-01-01

"It takes a lot of courage to release the familiar and seemingly secure, to embrace the new. But there is no real security in what is no longer meaningful. There is more security in the adventurous and exciting, for in movement there is life, and in change there is power." Alan Cohen (Used by permission. All rights reserved. For more information on Alan Cohen's books and programs, see (www.alancohen.com.) With the support of the East Tennessee State University (ETSU) administration and a grant from Howard Hughes Medical Institute, the departments of Biological Sciences, Mathematics and Statistics, and Curriculum and Instruction have developed a biology-math integrated curriculum. An interdisciplinary faculty team, charged with teaching the 18 curriculum modules, designed this three-semester curriculum, known as SYMBIOSIS. This curriculum was piloted to two student cohorts during the developmental stage. The positive feedback and assessment results of this project have given us the foundation to implement the SYMBIOSIS curriculum as a replacement for the standard biology majors curriculum at the introductory level. This article addresses the history and development of the curriculum, previous assessment results and current assessment protocol, and the future of ETSU's approach to implementing the SYMBIOSIS curriculum.

SYMBIOSIS: Development, Implementation, and Assessment of a Model Curriculum across Biology and Mathematics at the Introductory Level

PubMed Central

Joplin, Karl H.; Govett, Aimee; Miller, Hugh A.; Seier, Edith

2010-01-01

“It takes a lot of courage to release the familiar and seemingly secure, to embrace the new. But there is no real security in what is no longer meaningful. There is more security in the adventurous and exciting, for in movement there is life, and in change there is power.”Alan Cohen (Used by permission. All rights reserved. For more information on Alan Cohen's books and programs, see (www.alancohen.com.) With the support of the East Tennessee State University (ETSU) administration and a grant from Howard Hughes Medical Institute, the departments of Biological Sciences, Mathematics and Statistics, and Curriculum and Instruction have developed a biology–math integrated curriculum. An interdisciplinary faculty team, charged with teaching the 18 curriculum modules, designed this three-semester curriculum, known as SYMBIOSIS. This curriculum was piloted to two student cohorts during the developmental stage. The positive feedback and assessment results of this project have given us the foundation to implement the SYMBIOSIS curriculum as a replacement for the standard biology majors curriculum at the introductory level. This article addresses the history and development of the curriculum, previous assessment results and current assessment protocol, and the future of ETSU's approach to implementing the SYMBIOSIS curriculum. PMID:20810967

Strigolactones in the Rhizobium-legume symbiosis: Stimulatory effect on bacterial surface motility and down-regulation of their levels in nodulated plants.

PubMed

Peláez-Vico, María A; Bernabéu-Roda, Lydia; Kohlen, Wouter; Soto, María J; López-Ráez, Juan A

2016-04-01

Strigolactones (SLs) are multifunctional molecules acting as modulators of plant responses under nutrient deficient conditions. One of the roles of SLs is to promote beneficial association with arbuscular mycorrhizal (AM) fungi belowground under such stress conditions, mainly phosphorus shortage. Recently, a role of SLs in the Rhizobium-legume symbiosis has been also described. While SLs' function in AM symbiosis is well established, their role in the Rhizobium-legume interaction is still emerging. Recently, SLs have been suggested to stimulate surface motility of rhizobia, opening the possibility that they could also act as molecular cues. The possible effect of SLs in the motility in the alfalfa symbiont Sinorhizobium meliloti was investigated, showing that the synthetic SL analogue GR24 stimulates swarming motility in S. meliloti in a dose-dependent manner. On the other hand, it is known that SL production is regulated by nutrient deficient conditions and by AM symbiosis. Using the model alfalfa-S. meliloti, the impact of phosphorus and nitrogen deficiency, as well as of nodulation on SL production was also assessed. The results showed that phosphorus starvation promoted SL biosynthesis, which was abolished by nitrogen deficiency. In addition, a negative effect of nodulation on SL levels was detected, suggesting a conserved mechanism of SL regulation upon symbiosis establishment. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Phytoremediation of heavy and transition metals aided by legume-rhizobia symbiosis.

PubMed

Hao, X; Taghavi, S; Xie, P; Orbach, M J; Alwathnani, H A; Rensing, C; Wei, G

2014-01-01

Legumes are important for nitrogen cycling in the environment and agriculture due to the ability of nitrogen fixation by rhizobia. In this review, we introduce an important and potential role of legume-rhizobia symbiosis in aiding phytoremediation of some metal contaminated soils as various legumes have been found to be the dominant plant species in metal contaminated areas. Resistant rhizobia used for phytoremediation could act on metals directly by chelation, precipitation, transformation, biosorption and accumulation. Moreover, the plant growth promoting (PGP) traits of rhizobia including nitrogen fixation, phosphorus solubilization, phytohormone synthesis, siderophore release, and production of ACC deaminase and the volatile compounds of acetoin and 2, 3-butanediol may facilitate legume growth while lessening metal toxicity. The benefits of using legumes inoculated with naturally resistant rhizobia or recombinant rhizobia with enhanced resistance, as well as co-inoculation with other plant growth promoting bacteria (PGPB) are discussed. However, the legume-rhizobia symbiosis appears to be sensitive to metals, and the effect of metal toxicity on the interaction between legumes and rhizobia is not clear. Therefore, to obtain the maximum benefits from legumes assisted by rhizobia for phytoremediation of metals, it is critical to have a good understanding of interactions between PGP traits, the symbiotic plant-rhizobia relationship and metals.

Photosynthetic aeration in biological wastewater treatment using immobilized microalgae-bacteria symbiosis.

PubMed

Praveen, Prashant; Loh, Kai-Chee

2015-12-01

Chlorella vulgaris encapsulated in alginate beads were added into a bioreactor treating synthetic wastewater using Pseudomonas putida. A symbiotic CO2/O2 gas exchange was established between the two microorganisms for photosynthetic aeration of wastewater. During batch operation, glucose removal efficiency in the bioreactor improved from 50% in 12 h without aeration to 100% in 6 h, when the bioreactor was aerated photosynthetically. During continuous operation, the bioreactor was operated at a low hydraulic retention time of 3.3 h at feed concentrations of 250 and 500 mg/L glucose. The removal efficiency at 500 mg/L increased from 73% without aeration to 100% in the presence of immobilized microalgae. The initial microalgae concentration was critical to achieve adequate aeration, and the removal rate increased with increasing microalgae concentration. The highest removal rate of 142 mg/L-h glucose was achieved at an initial microalgae concentration of 190 mg/L. Quantification of microalgae growth in the alginate beads indicated an exponential growth during symbiosis, indicating that the bioreactor performance was limited by oxygen production rates. Under symbiotic conditions, the chlorophyll content of the immobilized microalgae increased by more than 30%. These results indicate that immobilized microalgae in symbiosis with heterotrophic bacteria are promising in wastewater aeration.

Academia-industry symbiosis in organic chemistry.

PubMed

Michaudel, Quentin; Ishihara, Yoshihiro; Baran, Phil S

2015-03-17

Collaboration between academia and industry is a growing phenomenon within the chemistry community. These sectors have long held strong ties since academia traditionally trains the future scientists of the corporate world, but the recent drastic decrease of public funding is motivating the academic world to seek more private grants. This concept of industrial "sponsoring" is not new, and in the past, some companies granted substantial amounts of money per annum to various academic institutions in exchange for prime access to all their scientific discoveries and inventions. However, academic and industrial interests were not always aligned, and therefore the investment has become increasingly difficult to justify from industry's point of view. With fluctuating macroeconomic factors, this type of unrestricted grant has become more rare and has been largely replaced by smaller and more focused partnerships. In our view, forging a partnership with industry can be a golden opportunity for both parties and can represent a true symbiosis. This type of project-specific collaboration is engendered by industry's desire to access very specific academic expertise that is required for the development of new technologies at the forefront of science. Since financial pressures do not allow companies to spend the time to acquire this expertise and even less to explore fundamental research, partnering with an academic laboratory whose research is related to the problem gives them a viable alternative. From an academic standpoint, it represents the perfect occasion to apply "pure science" research concepts to solve problems that benefit humanity. Moreover, it offers a unique opportunity for students to face challenges from the "real world" at an early stage of their career. Although not every problem in industry can be solved by research developments in academia, we argue that there is significant scientific overlap between these two seemingly disparate groups, thereby presenting an

Towards symbiosis in knowledge representation and natural language processing for structuring clinical practice guidelines.

PubMed

Weng, Chunhua; Payne, Philip R O; Velez, Mark; Johnson, Stephen B; Bakken, Suzanne

2014-01-01

The successful adoption by clinicians of evidence-based clinical practice guidelines (CPGs) contained in clinical information systems requires efficient translation of free-text guidelines into computable formats. Natural language processing (NLP) has the potential to improve the efficiency of such translation. However, it is laborious to develop NLP to structure free-text CPGs using existing formal knowledge representations (KR). In response to this challenge, this vision paper discusses the value and feasibility of supporting symbiosis in text-based knowledge acquisition (KA) and KR. We compare two ontologies: (1) an ontology manually created by domain experts for CPG eligibility criteria and (2) an upper-level ontology derived from a semantic pattern-based approach for automatic KA from CPG eligibility criteria text. Then we discuss the strengths and limitations of interweaving KA and NLP for KR purposes and important considerations for achieving the symbiosis of KR and NLP for structuring CPGs to achieve evidence-based clinical practice.

The Metronome of Symbiosis: Interactions Between Microbes and the Host Circadian Clock.

PubMed

Heath-Heckman, Elizabeth A C

2016-11-01

The entrainment of circadian rhythms, physiological cycles with a period of about 24 h, is regulated by a variety of mechanisms, including nonvisual photoreception. While circadian rhythms have been shown to be integral to many processes in multicellular organisms, including immune regulation, the effect of circadian rhythms on symbiosis, or host-microbe interactions, has only recently begun to be studied. This review summarizes recent work in the interactions of both pathogenic and mutualistic associations with host and symbiont circadian rhythms, focusing specifically on three mutualistic systems in which this phenomenon has been best studied. One important theme taken from these studies is the fact that mutualisms are profoundly affected by the circadian rhythms of the host, but that the microbial symbionts in these associations can, in turn, manipulate host rhythms. The interplay between circadian rhythms and symbiosis is a promising new field with effects that should be kept in mind when designing future studies across biology. © The Author 2016. Published by Oxford University Press on behalf of the Society for Integrative and Comparative Biology. All rights reserved. For permissions please email: journals.permissions@oup.com.

The first thousand days - intestinal microbiology of early life: establishing a symbiosis.

PubMed

Wopereis, Harm; Oozeer, Raish; Knipping, Karen; Belzer, Clara; Knol, Jan

2014-08-01

The development of the intestinal microbiota in the first years of life is a dynamic process significantly influenced by early-life nutrition. Pioneer bacteria colonizing the infant intestinal tract and the gradual diversification to a stable climax ecosystem plays a crucial role in establishing host-microbe interactions essential for optimal symbiosis. This colonization process and establishment of symbiosis may profoundly influence health throughout life. Recent developments in microbiologic cultivation-independent methods allow a detailed view of the key players and factors involved in this process and may further elucidate their roles in a healthy gut and immune maturation. Aberrant patterns may lead to identifying key microbial signatures involved in developing immunologic diseases into adulthood, such as asthma and atopic diseases. The central role of early-life nutrition in the developmental human microbiota, immunity, and metabolism offers promising strategies for prevention and treatment of such diseases. This review provides an overview of the development of the intestinal microbiota, its bidirectional relationship with the immune system, and its role in impacting health and disease, with emphasis on allergy, in early life. © 2014 Danone Nutricia Research. Pediatric Allergy and Immunology published by John Wiley & Sons Ltd.

Sea turtle symbiosis facilitates social monogamy in oceanic crabs via refuge size

PubMed Central

Gil, Michael A.

2016-01-01

The capacity for resource monopolization by individuals often dictates the size and composition of animal groups, and ultimately, the adoption of mating strategies. For refuge-dwelling animals, the ability (or inability) of individuals to monopolize refuges should depend on the relative size of the refuge. In theory, groups should be larger and more inclusive when refuges are large, and smaller and more exclusive when refuges are small, regardless of refuge type. We test this prediction by comparing the size and composition of groups of oceanic crabs (Planes minutus) living on plastic flotsam and loggerhead sea turtles. We found that (i) surface area of refuges (barnacle colonies on flotsam and supracaudal space on turtles) is a better predictor of crab number than total surface area and (ii) flotsam and turtles with similar refuge surface area host a similar number (1–2) and composition (adult male–female pairs) of crabs. These results indicate that group size and composition of refuge-dwelling animals are modulated by refuge size and the capacity for refuge monopolization. Moreover, these results suggest that sea turtle symbiosis facilitates social monogamy in oceanic crabs, providing insights into how symbiosis can promote specific mating strategies. PMID:27651538

Understanding regulation of the host-mediated gut symbiont population and the symbiont-mediated host immunity in the Riptortus-Burkholderia symbiosis system.

PubMed

Kim, Jiyeun Kate; Lee, Jun Beom; Jang, Ho Am; Han, Yeon Soo; Fukatsu, Takema; Lee, Bok Luel

2016-11-01

Valuable insect models have tremendously contributed to our understanding of innate immunity and symbiosis. Bean bug, Riptortus pedestris, is a useful insect symbiosis model due to harboring cultivable monospecific gut symbiont, genus Burkholderia. Bean bug is a hemimetabolous insect whose immunity is not well-understood. However, we recently identified three major antimicrobial peptides of Riptortus and examined the relationship between gut symbiosis and host immunity. We found that the presence of Burkholderia gut symbiont positively affects Riptortus immunity. From studying host regulation mechanisms of symbiont population, we revealed that the symbiotic Burkholderia cells are much more susceptible to Riptortus immune responses than the cultured cells. We further elucidated that the immune-susceptibility of the Burkholderia gut symbionts is due to the drastic change of bacterial cell envelope. Finally, we show that the immune-susceptible Burkholderia symbionts are able to prosper in host owing to the suppression of immune responses of the symbiotic midgut. Copyright © 2016 Elsevier Ltd. All rights reserved.

Metabolic Coevolution in the Bacterial Symbiosis of Whiteflies and Related Plant Sap-Feeding Insects.

PubMed

Luan, Jun-Bo; Chen, Wenbo; Hasegawa, Daniel K; Simmons, Alvin M; Wintermantel, William M; Ling, Kai-Shu; Fei, Zhangjun; Liu, Shu-Sheng; Douglas, Angela E

2015-09-15

Genomic decay is a common feature of intracellular bacteria that have entered into symbiosis with plant sap-feeding insects. This study of the whitefly Bemisia tabaci and two bacteria (Portiera aleyrodidarum and Hamiltonella defensa) cohoused in each host cell investigated whether the decay of Portiera metabolism genes is complemented by host and Hamiltonella genes, and compared the metabolic traits of the whitefly symbiosis with other sap-feeding insects (aphids, psyllids, and mealybugs). Parallel genomic and transcriptomic analysis revealed that the host genome contributes multiple metabolic reactions that complement or duplicate Portiera function, and that Hamiltonella may contribute multiple cofactors and one essential amino acid, lysine. Homologs of the Bemisia metabolism genes of insect origin have also been implicated in essential amino acid synthesis in other sap-feeding insect hosts, indicative of parallel coevolution of shared metabolic pathways across multiple symbioses. Further metabolism genes coded in the Bemisia genome are of bacterial origin, but phylogenetically distinct from Portiera, Hamiltonella and horizontally transferred genes identified in other sap-feeding insects. Overall, 75% of the metabolism genes of bacterial origin are functionally unique to one symbiosis, indicating that the evolutionary history of metabolic integration in these symbioses is strongly contingent on the pattern of horizontally acquired genes. Our analysis, further, shows that bacteria with genomic decay enable host acquisition of complex metabolic pathways by multiple independent horizontal gene transfers from exogenous bacteria. Specifically, each horizontally acquired gene can function with other genes in the pathway coded by the symbiont, while facilitating the decay of the symbiont gene coding the same reaction. © The Author(s) 2015. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

A Transcriptional Program for Arbuscule Degeneration during AM Symbiosis Is Regulated by MYB1.

PubMed

Floss, Daniela S; Gomez, S Karen; Park, Hee-Jin; MacLean, Allyson M; Müller, Lena M; Bhattarai, Kishor K; Lévesque-Tremblay, Veronique; Maldonado-Mendoza, Ignacio E; Harrison, Maria J

2017-04-24

During the endosymbiosis formed between plants and arbuscular mycorrhizal (AM) fungi, the root cortical cells are colonized by branched hyphae called arbuscules, which function in nutrient exchange with the plant [1]. Despite their positive function, arbuscules are ephemeral structures, and their development is followed by a degeneration phase, in which the arbuscule and surrounding periarbuscular membrane and matrix gradually disappear from the root cell [2, 3]. Currently, the root cell's role in this process and the underlying regulatory mechanisms are unknown. Here, by using a Medicago truncatula pt4 mutant in which arbuscules degenerate prematurely [4], we identified arbuscule degeneration-associated genes, of which 38% are predicted to encode secreted hydrolases, suggesting a role in disassembly of the arbuscule and interface. Through RNAi and analysis of an insertion mutant, we identified a symbiosis-specific MYB-like transcription factor (MYB1) that suppresses arbuscule degeneration in mtpt4. In myb1, expression of several degeneration-associated genes is reduced. Conversely, in roots constitutively overexpressing MYB1, expression of degeneration-associated genes is increased and subsequent development of symbiosis is impaired. MYB1-regulated gene expression is enhanced by DELLA proteins and is dependent on NSP1 [5], but not NSP2 [6]. Furthermore, MYB1 interacts with DELLA and NSP1. Our data identify a transcriptional program for arbuscule degeneration and reveal that its regulators include MYB1 in association with two transcriptional regulators, NSP1 and DELLA, both of which function in preceding phases of the symbiosis. We propose that the combinatorial use of transcription factors enables the sequential expression of transcriptional programs for arbuscule development and degeneration. Copyright © 2017 Elsevier Ltd. All rights reserved.

Comparative symbiotic plasmid analysis indicates that symbiosis gene ancestor type affects plasmid genetic evolution.

PubMed

Wang, X; Zhao, L; Zhang, L; Wu, Y; Chou, M; Wei, G

2018-07-01

Rhizobial symbiotic plasmids play vital roles in mutualistic symbiosis with legume plants by executing the functions of nodulation and nitrogen fixation. To explore the gene composition and genetic constitution of rhizobial symbiotic plasmids, comparison analyses of 24 rhizobial symbiotic plasmids derived from four rhizobial genera was carried out. Results illustrated that rhizobial symbiotic plasmids had higher proportion of functional genes participating in amino acid transport and metabolism, replication; recombination and repair; carbohydrate transport and metabolism; energy production and conversion and transcription. Mesorhizobium amorphae CCNWGS0123 symbiotic plasmid - pM0123d had similar gene composition with pR899b and pSNGR234a. All symbiotic plasmids shared 13 orthologous genes, including five nod and eight nif/fix genes which participate in the rhizobia-legume symbiosis process. These plasmids contained nod genes from four ancestors and fix genes from six ancestors. The ancestral type of pM0123d nod genes was similar with that of Rhizobium etli plasmids, while the ancestral type of pM0123d fix genes was same as that of pM7653Rb. The phylogenetic trees constructed based on nodCIJ and fixABC displayed different topological structures mainly due to nodCIJ and fixABC ancestral type discordance. The study presents valuable insights into mosaic structures and the evolution of rhizobial symbiotic plasmids. This study compared 24 rhizobial symbiotic plasmids that included four genera and 11 species, illuminating the functional gene composition and symbiosis gene ancestor types of symbiotic plasmids from higher taxonomy. It provides valuable insights into mosaic structures and the evolution of symbiotic plasmids. © 2018 The Society for Applied Microbiology.

Symbiosis and the origin of eukaryotic motility

NASA Technical Reports Server (NTRS)

Margulis, L.; Hinkle, G.

1991-01-01

Ongoing work to test the hypothesis of the origin of eukaryotic cell organelles by microbial symbioses is discussed. Because of the widespread acceptance of the serial endosymbiotic theory (SET) of the origin of plastids and mitochondria, the idea of the symbiotic origin of the centrioles and axonemes for spirochete bacteria motility symbiosis was tested. Intracellular microtubular systems are purported to derive from symbiotic associations between ancestral eukaryotic cells and motile bacteria. Four lines of approach to this problem are being pursued: (1) cloning the gene of a tubulin-like protein discovered in Spirocheata bajacaliforniesis; (2) seeking axoneme proteins in spirochets by antibody cross-reaction; (3) attempting to cultivate larger, free-living spirochetes; and (4) studying in detail spirochetes (e.g., Cristispira) symbiotic with marine animals. Other aspects of the investigation are presented.

Long-distance transport of signals during symbiosis

PubMed Central

Xie, Zhi-Ping; Illana, Antonio

2011-01-01

Legumes enter nodule symbioses with nitrogen-fixing bacteria (rhizobia), whereas most flowering plants establish symbiotic associations with arbuscular mycorrhizal (AM) fungi. Once first steps of symbiosis are initiated, nodule formation and mycorrhization in legumes is negatively controlled by a shoot-derived inhibitor (SDI), a phenomenon termed autoregulation. According to current views, autoregulation of nodulation and mycorrhization in legumes is regulated in a similar way. CLE peptides induced in response to rhizobial nodulation signals (Nod factors) have been proposed to represent the ascending long-distance signals to the shoot. Although not proven yet, these CLE peptides are likely perceived by leucine-rich repeat (LRR) autoregulation receptor kinases in the shoot. Autoregulation of mycorrhization in non-legumes is reminiscent to the phenomenon of “systemic acquired resistance” in plant-pathogen interactions. PMID:21455020

Symbiosis of sea anemones and hermit crabs: different resource utilization patterns in the Aegean Sea

NASA Astrophysics Data System (ADS)

Vafeiadou, Anna-Maria; Antoniadou, Chryssanthi; Chintiroglou, Chariton

2012-09-01

The small-scale distribution and resource utilization patterns of hermit crabs living in symbiosis with sea anemones were investigated in the Aegean Sea. Four hermit crab species, occupying shells of nine gastropod species, were found in symbiosis with the sea anemone Calliactis parasitica. Shell resource utilization patterns varied among hermit crabs, with Dardanus species utilizing a wide variety of shells. The size structure of hermit crab populations also affected shell resource utilization, with small-sized individuals inhabiting a larger variety of shells. Sea anemone utilization patterns varied both among hermit crab species and among residence shells, with larger crabs and shells hosting an increased abundance and biomass of C. parasitica. The examined biometric relationships suggested that small-sized crabs carry, proportionally to their weight, heavier shells and increased anemone biomass than larger ones. Exceptions to the above patterns are related either to local resource availability or to other environmental factors.

Arbuscular mycorrhizal symbiosis ameliorates the optimum quantum yield of photosystem II and reduces non-photochemical quenching in rice plants subjected to salt stress.

PubMed

Porcel, Rosa; Redondo-Gómez, Susana; Mateos-Naranjo, Enrique; Aroca, Ricardo; Garcia, Rosalva; Ruiz-Lozano, Juan Manuel

2015-08-01

Rice is the most important food crop in the world and is a primary source of food for more than half of the world population. However, salinity is considered the most common abiotic stress reducing its productivity. Soil salinity inhibits photosynthetic processes, which can induce an over-reduction of the reaction centres in photosystem II (PSII), damaging the photosynthetic machinery. The arbuscular mycorrhizal (AM) symbiosis may improve host plant tolerance to salinity, but it is not clear how the AM symbiosis affects the plant photosynthetic capacity, particularly the efficiency of PSII. This study aimed at determining the influence of the AM symbiosis on the performance of PSII in rice plants subjected to salinity. Photosynthetic activity, plant gas-exchange parameters, accumulation of photosynthetic pigments and rubisco activity and gene expression were also measured in order to analyse comprehensively the response of the photosynthetic processes to AM symbiosis and salinity. Results showed that the AM symbiosis enhanced the actual quantum yield of PSII photochemistry and reduced the quantum yield of non-photochemical quenching in rice plants subjected to salinity. AM rice plants maintained higher net photosynthetic rate, stomatal conductance and transpiration rate than nonAM plants. Thus, we propose that AM rice plants had a higher photochemical efficiency for CO2 fixation and solar energy utilization and this increases plant salt tolerance by preventing the injury to the photosystems reaction centres and by allowing a better utilization of light energy in photochemical processes. All these processes translated into higher photosynthetic and rubisco activities in AM rice plants and improved plant biomass production under salinity. Copyright © 2015 Elsevier GmbH. All rights reserved.

A Lipidomic Approach to Understanding Free Fatty Acid Lipogenesis Derived from Dissolved Inorganic Carbon within Cnidarian-Dinoflagellate Symbiosis

PubMed Central

Dunn, Simon R.; Thomas, Michael C.; Nette, Geoffrey W.; Dove, Sophie G.

2012-01-01

The cnidarian-dinoflagellate symbiosis is arguably one of the most important within the marine environment in that it is integral to the formation of coral reefs. However, the regulatory processes that perpetuate this symbiosis remain unresolved. It is essential to understand these processes, if we are to elucidate the mechanisms that support growth and resource accumulation by coral host, and conversely, recently observed reduction and/or mortality of corals in response to rapid environmental change. This study specifically focused on one area of metabolic activity within the symbiosis, that of free fatty acid synthesis within both the dinoflagellate symbionts and cnidarian host. The main model system used was Aiptasia pulchella and Symbiodinium sp. in combination with aposymbiotic A. pulchella, the symbiotic coral Acropora millepora system and dinoflagellate culture. Fatty acids (FAs) were selected because of their multiple essential roles inclusive of energy storage (resource accumulation), membrane structure fluidity and cell signaling. The study addressed free FA lipogenesis by using a new method of enriched stable isotopic (13C) incorporation from dissolved inorganic carbon (DI13C) combined with HPLC-MS. FAs derived from DI13C aligned with a mixture of known lipogenesis pathways with the addition of some unusual FAs. After 120 hr, 13C-enriched FA synthesis rates were attributed to only a complex integration of both n–3 and n–6 lipogenesis pathways within the dinoflagellate symbionts. Furthermore, there was no detectible evidence of symbiont derived enriched isotope fatty acids, catabolized 13C derivatives or DI13C being directly utilized, in host late n–6 pathway long-chain FA lipogenesis. These findings do not align with a popular mutualistic translocation model with respect to the use of translocated symbiont photoassimilates in host long-chain FA lipogenesis, which has important connotations for linking nutrient sources with metabolite production and

Non-nodulated bacterial leaf symbiosis promotes the evolutionary success of its host plants in the coffee family (Rubiaceae).

PubMed

Verstraete, Brecht; Janssens, Steven; Rønsted, Nina

2017-08-01

Every plant species on Earth interacts in some way or another with microorganisms and it is well known that certain forms of symbiosis between different organisms can drive evolution. Within some clades of Rubiaceae (coffee family), a specific plant-bacteria interaction exists in which non-pathological endophytes are present in the leaves of their hosts. It is hypothesized that the bacterial endophytes, either alone or by interacting with the host, provide chemical protection against herbivory or pathogens by producing toxic or otherwise advantageous secondary metabolites. If the bacteria indeed have a direct beneficial influence on their hosts, it is reasonable to assume that the endophytes may increase the fitness of their hosts and therefore it is probable that their presence also has an influence on the long-term evolution of the particular plant lineages. In this study, the possible origin in time of non-nodulated bacterial leaf symbiosis in the Vanguerieae tribe of Rubiaceae is elucidated and dissimilarities in evolutionary dynamics between species with endophytes versus species without are investigated. Bacterial leaf symbiosis is shown to have most probably originated in the Late Miocene, a period when the savannah habitat is believed to have expanded on the African continent and herbivore pressure increased. The presence of bacterial leaf endophytes appears to be restricted to Old World lineages so far. Plant lineages with leaf endophytes show a significantly higher speciation rate than plant lineages without endophytes, while there is only a small difference in extinction rate. The transition rate shows that evolving towards having endophytes is twice as fast as evolving towards not having endophytes, suggesting that leaf symbiosis must be beneficial for the host plants. We conclude that the presence of bacterial leaf endophytes may also be an important driver for speciation of host plants. Copyright © 2017 Elsevier Inc. All rights reserved.

A lipidomic approach to understanding free fatty acid lipogenesis derived from dissolved inorganic carbon within cnidarian-dinoflagellate symbiosis.

PubMed

Dunn, Simon R; Thomas, Michael C; Nette, Geoffrey W; Dove, Sophie G

2012-01-01

The cnidarian-dinoflagellate symbiosis is arguably one of the most important within the marine environment in that it is integral to the formation of coral reefs. However, the regulatory processes that perpetuate this symbiosis remain unresolved. It is essential to understand these processes, if we are to elucidate the mechanisms that support growth and resource accumulation by coral host, and conversely, recently observed reduction and/or mortality of corals in response to rapid environmental change. This study specifically focused on one area of metabolic activity within the symbiosis, that of free fatty acid synthesis within both the dinoflagellate symbionts and cnidarian host. The main model system used was Aiptasia pulchella and Symbiodinium sp. in combination with aposymbiotic A. pulchella, the symbiotic coral Acropora millepora system and dinoflagellate culture. Fatty acids (FAs) were selected because of their multiple essential roles inclusive of energy storage (resource accumulation), membrane structure fluidity and cell signaling. The study addressed free FA lipogenesis by using a new method of enriched stable isotopic ((13)C) incorporation from dissolved inorganic carbon (DI(13)C) combined with HPLC-MS. FAs derived from DI(13)C aligned with a mixture of known lipogenesis pathways with the addition of some unusual FAs. After 120 hr, (13)C-enriched FA synthesis rates were attributed to only a complex integration of both n-3 and n-6 lipogenesis pathways within the dinoflagellate symbionts. Furthermore, there was no detectible evidence of symbiont derived enriched isotope fatty acids, catabolized (13)C derivatives or DI(13)C being directly utilized, in host late n-6 pathway long-chain FA lipogenesis. These findings do not align with a popular mutualistic translocation model with respect to the use of translocated symbiont photoassimilates in host long-chain FA lipogenesis, which has important connotations for linking nutrient sources with metabolite

Toward a better understanding of the mechanisms of symbiosis: a comprehensive proteome map of a nascent insect symbiont.

PubMed

Renoz, François; Champagne, Antoine; Degand, Hervé; Faber, Anne-Marie; Morsomme, Pierre; Foray, Vincent; Hance, Thierry

2017-01-01

Symbiotic bacteria are common in insects and can affect various aspects of their hosts' biology. Although the effects of insect symbionts have been clarified for various insect symbiosis models, due to the difficulty of cultivating them in vitro , there is still limited knowledge available on the molecular features that drive symbiosis. Serratia symbiotica is one of the most common symbionts found in aphids. The recent findings of free-living strains that are considered as nascent partners of aphids provide the opportunity to examine the molecular mechanisms that a symbiont can deploy at the early stages of the symbiosis (i.e., symbiotic factors). In this work, a proteomic approach was used to establish a comprehensive proteome map of the free-living S. symbiotica strain CWBI-2.3 T . Most of the 720 proteins identified are related to housekeeping or primary metabolism. Of these, 76 were identified as candidate proteins possibly promoting host colonization. Our results provide strong evidence that S. symbiotica CWBI-2.3 T is well-armed for invading insect host tissues, and suggest that certain molecular features usually harbored by pathogenic bacteria are no longer present. This comprehensive proteome map provides a series of candidate genes for further studies to understand the molecular cross-talk between insects and symbiotic bacteria.

The nitrate-reduction gene cluster components exert lineage-dependent contributions to optimization of Sinorhizobium symbiosis with soybeans.

PubMed

Liu, Li Xue; Li, Qin Qin; Zhang, Yun Zeng; Hu, Yue; Jiao, Jian; Guo, Hui Juan; Zhang, Xing Xing; Zhang, Biliang; Chen, Wen Xin; Tian, Chang Fu

2017-12-01

Receiving nodulation and nitrogen fixation genes does not guarantee rhizobia an effective symbiosis with legumes. Here, variations in gene content were determined for three Sinorhizobium species showing contrasting symbiotic efficiency on soybeans. A nitrate-reduction gene cluster absent in S. sojae was found to be essential for symbiotic adaptations of S. fredii and S. sp. III. In S. fredii, the deletion mutation of the nap (nitrate reductase), instead of nir (nitrite reductase) and nor (nitric oxide reductase), led to defects in nitrogen-fixation (Fix - ). By contrast, none of these core nitrate-reduction genes were required for the symbiosis of S. sp. III. However, within the same gene cluster, the deletion of hemN1 (encoding oxygen-independent coproporphyrinogen III oxidase) in both S. fredii and S. sp. III led to the formation of nitrogen-fixing (Fix + ) but ineffective (Eff - ) nodules. These Fix + /Eff - nodules were characterized by significantly lower enzyme activity of glutamine synthetase indicating rhizobial modulation of nitrogen-assimilation by plants. A distant homologue of HemN1 from S. sojae can complement this defect in S. fredii and S. sp. III, but exhibited a more pleotropic role in symbiosis establishment. These findings highlighted the lineage-dependent optimization of symbiotic functions in different rhizobial species associated with the same host. © 2017 Society for Applied Microbiology and John Wiley & Sons Ltd.

The Laccaria and Tuber Genomes Reveal Unique Signatures of Mycorrhizal Symbiosis Evolution (2010 JGI User Meeting)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Martin, Francis

Francis Martin from the French National Institute for Agricultural Research (INRA) talks on how "The Laccaria and Tuber genomes reveal unique signatures of mycorrhizal symbiosis evolution" on March 24, 2010 at the 5th Annual DOE JGI User Meeting

Harnessing mosquito-Wolbachia symbiosis for vector and disease control.

PubMed

Bourtzis, Kostas; Dobson, Stephen L; Xi, Zhiyong; Rasgon, Jason L; Calvitti, Maurizio; Moreira, Luciano A; Bossin, Hervé C; Moretti, Riccardo; Baton, Luke Anthony; Hughes, Grant L; Mavingui, Patrick; Gilles, Jeremie R L

2014-04-01

Mosquito species, members of the genera Aedes, Anopheles and Culex, are the major vectors of human pathogens including protozoa (Plasmodium sp.), filariae and of a variety of viruses (causing dengue, chikungunya, yellow fever, West Nile). There is lack of efficient methods and tools to treat many of the diseases caused by these major human pathogens, since no efficient vaccines or drugs are available; even in malaria where insecticide use and drug therapies have reduced incidence, 219 million cases still occurred in 2010. Therefore efforts are currently focused on the control of vector populations. Insecticides alone are insufficient to control mosquito populations since reduced susceptibility and even resistance is being observed more and more frequently. There is also increased concern about the toxic effects of insecticides on non-target (even beneficial) insect populations, on humans and the environment. During recent years, the role of symbionts in the biology, ecology and evolution of insect species has been well-documented and has led to suggestions that they could potentially be used as tools to control pests and therefore diseases. Wolbachia is perhaps the most renowned insect symbiont, mainly due to its ability to manipulate insect reproduction and to interfere with major human pathogens thus providing new avenues for pest control. We herein present recent achievements in the field of mosquito-Wolbachia symbiosis with an emphasis on Aedes albopictus. We also discuss how Wolbachia symbiosis can be harnessed for vector control as well as the potential to combine the sterile insect technique and Wolbachia-based approaches for the enhancement of population suppression programs. Copyright © 2013 International Atomic Energy Agency 2013. Published by Elsevier B.V. All rights reserved.

Species specificity of symbiosis and secondary metabolism in ascidians.

PubMed

Tianero, Ma Diarey B; Kwan, Jason C; Wyche, Thomas P; Presson, Angela P; Koch, Michael; Barrows, Louis R; Bugni, Tim S; Schmidt, Eric W

2015-03-01

Ascidians contain abundant, diverse secondary metabolites, which are thought to serve a defensive role and which have been applied to drug discovery. It is known that bacteria in symbiosis with ascidians produce several of these metabolites, but very little is known about factors governing these 'chemical symbioses'. To examine this phenomenon across a wide geographical and species scale, we performed bacterial and chemical analyses of 32 different ascidians, mostly from the didemnid family from Florida, Southern California and a broad expanse of the tropical Pacific Ocean. Bacterial diversity analysis showed that ascidian microbiomes are highly diverse, and this diversity does not correlate with geographical location or latitude. Within a subset of species, ascidian microbiomes are also stable over time (R=-0.037, P-value=0.499). Ascidian microbiomes and metabolomes contain species-specific and location-specific components. Location-specific bacteria are found in low abundance in the ascidians and mostly represent strains that are widespread. Location-specific metabolites consist largely of lipids, which may reflect differences in water temperature. By contrast, species-specific bacteria are mostly abundant sequenced components of the microbiomes and include secondary metabolite producers as major components. Species-specific chemicals are dominated by secondary metabolites. Together with previous analyses that focused on single ascidian species or symbiont type, these results reveal fundamental properties of secondary metabolic symbiosis. Different ascidian species have established associations with many different bacterial symbionts, including those known to produce toxic chemicals. This implies a strong selection for this property and the independent origin of secondary metabolite-based associations in different ascidian species. The analysis here streamlines the connection of secondary metabolite to producing bacterium, enabling further biological and

Populus trichocarpa encodes small, effector-like secreted proteins that are highly induced during mutualistic symbiosis

DOE PAGES

Plett, Jonathan M.; Yin, Hengfu; Mewalal, Ritesh; ...

2017-03-23

During symbiosis, organisms use a range of metabolic and protein-based signals to communicate. Of these protein signals, one class is defined as ‘effectors’, i.e., small secreted proteins (SSPs) that cause phenotypical and physiological changes in another organism. To date, protein-based effectors have been described in aphids, nematodes, fungi and bacteria. Using RNA sequencing of Populus trichocarpa roots in mutualistic symbiosis with the ectomycorrhizal fungus Laccaria bicolor, we sought to determine if host plants also contain genes encoding effector-like proteins. We identified 417 plant-encoded putative SSPs that were significantly regulated during this interaction, including 161 SSPs specific to P. trichocarpa andmore » 15 SSPs exhibiting expansion in Populus and closely related lineages. We demonstrate that a subset of these SSPs can enter L. bicolor hyphae, localize to the nucleus and affect hyphal growth and morphology. Finally, we conclude that plants encode proteins that appear to function as effector proteins that may regulate symbiotic associations.« less

Design for sustainability of industrial symbiosis based on emergy and multi-objective particle swarm optimization.

PubMed

Ren, Jingzheng; Liang, Hanwei; Dong, Liang; Sun, Lu; Gao, Zhiqiu

2016-08-15

Industrial symbiosis provides novel and practical pathway to the design for the sustainability. Decision support tool for its verification is necessary for practitioners and policy makers, while to date, quantitative research is limited. The objective of this work is to present an innovative approach for supporting decision-making in the design for the sustainability with the implementation of industrial symbiosis in chemical complex. Through incorporating the emergy theory, the model is formulated as a multi-objective approach that can optimize both the economic benefit and sustainable performance of the integrated industrial system. A set of emergy based evaluation index are designed. Multi-objective Particle Swarm Algorithm is proposed to solve the model, and the decision-makers are allowed to choose the suitable solutions form the Pareto solutions. An illustrative case has been studied by the proposed method, a few of compromises between high profitability and high sustainability can be obtained for the decision-makers/stakeholders to make decision. Copyright © 2016 Elsevier B.V. All rights reserved.

Populus trichocarpa encodes small, effector-like secreted proteins that are highly induced during mutualistic symbiosis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Plett, Jonathan M.; Yin, Hengfu; Mewalal, Ritesh

During symbiosis, organisms use a range of metabolic and protein-based signals to communicate. Of these protein signals, one class is defined as ‘effectors’, i.e., small secreted proteins (SSPs) that cause phenotypical and physiological changes in another organism. To date, protein-based effectors have been described in aphids, nematodes, fungi and bacteria. Using RNA sequencing of Populus trichocarpa roots in mutualistic symbiosis with the ectomycorrhizal fungus Laccaria bicolor, we sought to determine if host plants also contain genes encoding effector-like proteins. We identified 417 plant-encoded putative SSPs that were significantly regulated during this interaction, including 161 SSPs specific to P. trichocarpa andmore » 15 SSPs exhibiting expansion in Populus and closely related lineages. We demonstrate that a subset of these SSPs can enter L. bicolor hyphae, localize to the nucleus and affect hyphal growth and morphology. Finally, we conclude that plants encode proteins that appear to function as effector proteins that may regulate symbiotic associations.« less

The plasma membrane proteome of Medicago truncatula roots as modified by arbuscular mycorrhizal symbiosis.

PubMed

Aloui, Achref; Recorbet, Ghislaine; Lemaître-Guillier, Christelle; Mounier, Arnaud; Balliau, Thierry; Zivy, Michel; Wipf, Daniel; Dumas-Gaudot, Eliane

2018-01-01

In arbuscular mycorrhizal (AM) roots, the plasma membrane (PM) of the host plant is involved in all developmental stages of the symbiotic interaction, from initial recognition to intracellular accommodation of intra-radical hyphae and arbuscules. Although the role of the PM as the agent for cellular morphogenesis and nutrient exchange is especially accentuated in endosymbiosis, very little is known regarding the PM protein composition of mycorrhizal roots. To obtain a global overview at the proteome level of the host PM proteins as modified by symbiosis, we performed a comparative protein profiling of PM fractions from Medicago truncatula roots either inoculated or not with the AM fungus Rhizophagus irregularis. PM proteins were isolated from root microsomes using an optimized discontinuous sucrose gradient; their subsequent analysis by liquid chromatography followed by mass spectrometry (MS) identified 674 proteins. Cross-species sequence homology searches combined with MS-based quantification clearly confirmed enrichment in PM-associated proteins and depletion of major microsomal contaminants. Changes in protein amounts between the PM proteomes of mycorrhizal and non-mycorrhizal roots were monitored further by spectral counting. This workflow identified a set of 82 mycorrhiza-responsive proteins that provided insights into the plant PM response to mycorrhizal symbiosis. Among them, the association of one third of the mycorrhiza-responsive proteins with detergent-resistant membranes pointed at partitioning to PM microdomains. The PM-associated proteins responsive to mycorrhization also supported host plant control of sugar uptake to limit fungal colonization, and lipid turnover events in the PM fraction of symbiotic roots. Because of the depletion upon symbiosis of proteins mediating the replacement of phospholipids by phosphorus-free lipids in the plasmalemma, we propose a role of phosphate nutrition in the PM composition of mycorrhizal roots.

A Nostoc punctiforme sugar transporter necessary to establish a Cyanobacterium-plant symbiosis.

PubMed

Ekman, Martin; Picossi, Silvia; Campbell, Elsie L; Meeks, John C; Flores, Enrique

2013-04-01

In cyanobacteria-plant symbioses, the symbiotic nitrogen-fixing cyanobacterium has low photosynthetic activity and is supplemented by sugars provided by the plant partner. Which sugars and cyanobacterial sugar uptake mechanism(s) are involved in the symbiosis, however, is unknown. Mutants of the symbiotically competent, facultatively heterotrophic cyanobacterium Nostoc punctiforme were constructed bearing a neomycin resistance gene cassette replacing genes in a putative sugar transport gene cluster. Results of transport activity assays using (14)C-labeled fructose and glucose and tests of heterotrophic growth with these sugars enabled the identification of an ATP-binding cassette-type transporter for fructose (Frt), a major facilitator permease for glucose (GlcP), and a porin needed for the optimal uptake of both fructose and glucose. Analysis of green fluorescent protein fluorescence in strains of N. punctiforme bearing frt::gfp fusions showed high expression in vegetative cells and akinetes, variable expression in hormogonia, and no expression in heterocysts. The symbiotic efficiency of N. punctiforme sugar transport mutants was investigated by testing their ability to infect a nonvascular plant partner, the hornwort Anthoceros punctatus. Strains that were specifically unable to transport glucose did not infect the plant. These results imply a role for GlcP in establishing symbiosis under the conditions used in this work.

Sea turtle symbiosis facilitates social monogamy in oceanic crabs via refuge size.

PubMed

Pfaller, Joseph B; Gil, Michael A

2016-09-01

The capacity for resource monopolization by individuals often dictates the size and composition of animal groups, and ultimately, the adoption of mating strategies. For refuge-dwelling animals, the ability (or inability) of individuals to monopolize refuges should depend on the relative size of the refuge. In theory, groups should be larger and more inclusive when refuges are large, and smaller and more exclusive when refuges are small, regardless of refuge type. We test this prediction by comparing the size and composition of groups of oceanic crabs (Planes minutus) living on plastic flotsam and loggerhead sea turtles. We found that (i) surface area of refuges (barnacle colonies on flotsam and supracaudal space on turtles) is a better predictor of crab number than total surface area and (ii) flotsam and turtles with similar refuge surface area host a similar number (1-2) and composition (adult male-female pairs) of crabs. These results indicate that group size and composition of refuge-dwelling animals are modulated by refuge size and the capacity for refuge monopolization. Moreover, these results suggest that sea turtle symbiosis facilitates social monogamy in oceanic crabs, providing insights into how symbiosis can promote specific mating strategies. © 2016 The Author(s).

Academia–Industry Symbiosis in Organic Chemistry

PubMed Central

2015-01-01

Conspectus Collaboration between academia and industry is a growing phenomenon within the chemistry community. These sectors have long held strong ties since academia traditionally trains the future scientists of the corporate world, but the recent drastic decrease of public funding is motivating the academic world to seek more private grants. This concept of industrial “sponsoring” is not new, and in the past, some companies granted substantial amounts of money per annum to various academic institutions in exchange for prime access to all their scientific discoveries and inventions. However, academic and industrial interests were not always aligned, and therefore the investment has become increasingly difficult to justify from industry’s point of view. With fluctuating macroeconomic factors, this type of unrestricted grant has become more rare and has been largely replaced by smaller and more focused partnerships. In our view, forging a partnership with industry can be a golden opportunity for both parties and can represent a true symbiosis. This type of project-specific collaboration is engendered by industry’s desire to access very specific academic expertise that is required for the development of new technologies at the forefront of science. Since financial pressures do not allow companies to spend the time to acquire this expertise and even less to explore fundamental research, partnering with an academic laboratory whose research is related to the problem gives them a viable alternative. From an academic standpoint, it represents the perfect occasion to apply “pure science” research concepts to solve problems that benefit humanity. Moreover, it offers a unique opportunity for students to face challenges from the “real world” at an early stage of their career. Although not every problem in industry can be solved by research developments in academia, we argue that there is significant scientific overlap between these two seemingly disparate

Heterologous Complementation Reveals a Specialized Activity for BacA in the Medicago-Sinorhizobium meliloti Symbiosis.

PubMed

diCenzo, George C; Zamani, Maryam; Ludwig, Hannah N; Finan, Turlough M

2017-04-01

The bacterium Sinorhizobium meliloti Rm2011 forms N 2 -fixing root nodules on alfalfa and other leguminous plants. The pSymB chromid contains a 110-kb region (the ETR region) showing high synteny to a chromosomally located region in Sinorhizobium fredii NGR234 and related rhizobia. We recently introduced the ETR region from S. fredii NGR234 into the S. meliloti chromosome. Here, we report that, unexpectedly, the S. fredii NGR234 ETR region did not complement deletion of the S. meliloti ETR region in symbiosis with Medicago sativa. This phenotype was due to the bacA gene of NGR234 not being functionally interchangeable with the S. meliloti bacA gene during M. sativa symbiosis. Further analysis revealed that, whereas bacA genes from S. fredii or Rhizobium leguminosarum bv. viciae 3841 failed to complement the Fix - phenotype of a S. meliloti bacA mutant with M. sativa, they allowed for further developmental progression prior to a loss of viability. In contrast, with Melilotus alba, bacA from S. fredii and R. leguminosarum supported N 2 fixation by a S. meliloti bacA mutant. Additionally, the S. meliloti bacA gene can support N 2 fixation of a R. leguminosarum bacA mutant during symbiosis with Pisum sativum. A phylogeny of BacA proteins illustrated that S. meliloti BacA has rapidly diverged from most rhizobia and has converged toward the sequence of pathogenic genera Brucella and Escherichia. These data suggest that the S. meliloti BacA has evolved toward a specific interaction with Medicago and highlights the limitations of using a single model system for the study of complex biological topics.

Advancing the science of microbial symbiosis to support invasive species management: a case study on Phragmites in the Great Lakes

PubMed Central

Kowalski, Kurt P.; Bacon, Charles; Bickford, Wesley; Braun, Heather; Clay, Keith; Leduc-Lapierre, Michèle; Lillard, Elizabeth; McCormick, Melissa K.; Nelson, Eric; Torres, Monica; White, James; Wilcox, Douglas A.

2015-01-01

A growing body of literature supports microbial symbiosis as a foundational principle for the competitive success of invasive plant species. Further exploration of the relationships between invasive species and their associated microbiomes, as well as the interactions with the microbiomes of native species, can lead to key new insights into invasive success and potentially new and effective control approaches. In this manuscript, we review microbial relationships with plants, outline steps necessary to develop invasive species control strategies that are based on those relationships, and use the invasive plant species Phragmites australis (common reed) as an example of how development of microbial-based control strategies can be enhanced using a collective impact approach. The proposed science agenda, developed by the Collaborative for Microbial Symbiosis and Phragmites Management, contains a foundation of sequential steps and mutually-reinforcing tasks to guide the development of microbial-based control strategies for Phragmites and other invasive species. Just as the science of plant-microbial symbiosis can be transferred for use in other invasive species, so too can the model of collective impact be applied to other avenues of research and management. PMID:25745417

Advancing the science of microbial symbiosis to support invasive species management: a case study on Phragmites in the Great Lakes.

PubMed

Kowalski, Kurt P; Bacon, Charles; Bickford, Wesley; Braun, Heather; Clay, Keith; Leduc-Lapierre, Michèle; Lillard, Elizabeth; McCormick, Melissa K; Nelson, Eric; Torres, Monica; White, James; Wilcox, Douglas A

2015-01-01

A growing body of literature supports microbial symbiosis as a foundational principle for the competitive success of invasive plant species. Further exploration of the relationships between invasive species and their associated microbiomes, as well as the interactions with the microbiomes of native species, can lead to key new insights into invasive success and potentially new and effective control approaches. In this manuscript, we review microbial relationships with plants, outline steps necessary to develop invasive species control strategies that are based on those relationships, and use the invasive plant species Phragmites australis (common reed) as an example of how development of microbial-based control strategies can be enhanced using a collective impact approach. The proposed science agenda, developed by the Collaborative for Microbial Symbiosis and Phragmites Management, contains a foundation of sequential steps and mutually-reinforcing tasks to guide the development of microbial-based control strategies for Phragmites and other invasive species. Just as the science of plant-microbial symbiosis can be transferred for use in other invasive species, so too can the model of collective impact be applied to other avenues of research and management.

Advancing the science of microbial symbiosis to support invasive species management: a case study on Phragmites in the Great Lakes

USGS Publications Warehouse

Kowalski, Kurt P.; Bacon, Charles R.; Bickford, Wesley A.; Braun, Heather A.; Clay, Keith; Leduc-Lapierre, Michele; Lillard, Elizabeth; McCormick, Melissa K.; Nelson, Eric; Torres, Monica; White, James W. C.; Wilcox, Douglas A.

2015-01-01

A growing body of literature supports microbial symbiosis as a foundational principle for the competitive success of invasive plant species. Further exploration of the relationships between invasive species and their associated microbiomes, as well as the interactions with the microbiomes of native species, can lead to key new insights into invasive success and potentially new and effective control approaches. In this manuscript, we review microbial relationships with plants, outline steps necessary to develop invasive species control strategies that are based on those relationships, and use the invasive plant species Phragmites australis (common reed) as an example of how development of microbial-based control strategies can be enhanced using a collective impact approach. The proposed science agenda, developed by the Collaborative for Microbial Symbiosis andPhragmites Management, contains a foundation of sequential steps and mutually-reinforcing tasks to guide the development of microbial-based control strategies for Phragmites and other invasive species. Just as the science of plant-microbial symbiosis can be transferred for use in other invasive species, so too can the model of collective impact be applied to other avenues of research and management.

Lichen Symbiosis: Nature's High Yielding Machines for Induced Hydrogen Production

PubMed Central

Papazi, Aikaterini; Kastanaki, Elizabeth; Pirintsos, Stergios; Kotzabasis, Kiriakos

2015-01-01

Hydrogen is a promising future energy source. Although the ability of green algae to produce hydrogen has long been recognized (since 1939) and several biotechnological applications have been attempted, the greatest obstacle, being the O2-sensitivity of the hydrogenase enzyme, has not yet been overcome. In the present contribution, 75 years after the first report on algal hydrogen production, taking advantage of a natural mechanism of oxygen balance, we demonstrate high hydrogen yields by lichens. Lichens have been selected as the ideal organisms in nature for hydrogen production, since they consist of a mycobiont and a photobiont in symbiosis. It has been hypothesized that the mycobiont’s and photobiont’s consumption of oxygen (increase of COX and AOX proteins of mitochondrial respiratory pathways and PTOX protein of chrolorespiration) establishes the required anoxic conditions for the activation of the phycobiont’s hydrogenase in a closed system. Our results clearly supported the above hypothesis, showing that lichens have the ability to activate appropriate bioenergetic pathways depending on the specific incubation conditions. Under light conditions, they successfully use the PSII-dependent and the PSII-independent pathways (decrease of D1 protein and parallel increase of PSaA protein) to transfer electrons to hydrogenase, while under dark conditions, lichens use the PFOR enzyme and the dark fermentative pathway to supply electrons to hydrogenase. These advantages of lichen symbiosis in combination with their ability to survive in extreme environments (while in a dry state) constitute them as unique and valuable hydrogen producing natural factories and pave the way for future biotechnological applications. PMID:25826211

Enhanced Drought Stress Tolerance by the Arbuscular Mycorrhizal Symbiosis in a Drought-Sensitive Maize Cultivar Is Related to a Broader and Differential Regulation of Host Plant Aquaporins than in a Drought-Tolerant Cultivar

PubMed Central

Quiroga, Gabriela; Erice, Gorka; Aroca, Ricardo; Chaumont, François; Ruiz-Lozano, Juan M.

2017-01-01

The arbuscular mycorrhizal (AM) symbiosis has been shown to improve maize tolerance to different drought stress scenarios by regulating a wide range of host plants aquaporins. The objective of this study was to highlight the differences in aquaporin regulation by comparing the effects of the AM symbiosis on root aquaporin gene expression and plant physiology in two maize cultivars with contrasting drought sensitivity. This information would help to identify key aquaporin genes involved in the enhanced drought tolerance by the AM symbiosis. Results showed that when plants were subjected to drought stress the AM symbiosis induced a higher improvement of physiological parameters in drought-sensitive plants than in drought-tolerant plants. These include efficiency of photosystem II, membrane stability, accumulation of soluble sugars and plant biomass production. Thus, drought-sensitive plants obtained higher physiological benefit from the AM symbiosis. In addition, the genes ZmPIP1;1, ZmPIP1;3, ZmPIP1;4, ZmPIP1;6, ZmPIP2;2, ZmPIP2;4, ZmTIP1;1, and ZmTIP2;3 were down-regulated by the AM symbiosis in the drought-sensitive cultivar and only ZmTIP4;1 was up-regulated. In contrast, in the drought-tolerant cultivar only three of the studied aquaporin genes (ZmPIP1;6, ZmPIP2;2, and ZmTIP4;1) were regulated by the AM symbiosis, resulting induced. Results in the drought-sensitive cultivar are in line with the hypothesis that down-regulation of aquaporins under water deprivation could be a way to minimize water loss, and the AM symbiosis could be helping the plant in this regulation. Indeed, during drought stress episodes, water conservation is critical for plant survival and productivity, and is achieved by an efficient uptake and stringently regulated water loss, in which aquaporins participate. Moreover, the broader and contrasting regulation of these aquaporins by the AM symbiosis in the drought-sensitive than the drought-tolerant cultivar suggests a role of these aquaporins

Integrated metabolism in sponge-microbe symbiosis revealed by genome-centered metatranscriptomics.

PubMed

Moitinho-Silva, Lucas; Díez-Vives, Cristina; Batani, Giampiero; Esteves, Ana Is; Jahn, Martin T; Thomas, Torsten

2017-07-01

Despite an increased understanding of functions in sponge microbiomes, the interactions among the symbionts and between symbionts and host are not well characterized. Here we reconstructed the metabolic interactions within the sponge Cymbastela concentrica microbiome in the context of functional features of symbiotic diatoms and the host. Three genome bins (CcPhy, CcNi and CcThau) were recovered from metagenomic data of C. concentrica, belonging to the proteobacterial family Phyllobacteriaceae, the Nitrospira genus and the thaumarchaeal order Nitrosopumilales. Gene expression was estimated by mapping C. concentrica metatranscriptomic reads. Our analyses indicated that CcPhy is heterotrophic, while CcNi and CcThau are chemolithoautotrophs. CcPhy expressed many transporters for the acquisition of dissolved organic compounds, likely available through the sponge's filtration activity and symbiotic carbon fixation. Coupled nitrification by CcThau and CcNi was reconstructed, supported by the observed close proximity of the cells in fluorescence in situ hybridization. CcPhy facultative anaerobic respiration and assimilation by diatoms may consume the resulting nitrate. Transcriptional analysis of diatom and sponge functions indicated that these organisms are likely sources of organic compounds, for example, creatine/creatinine and dissolved organic carbon, for other members of the symbiosis. Our results suggest that organic nitrogen compounds, for example, creatine, creatinine, urea and cyanate, fuel the nitrogen cycle within the sponge. This study provides an unprecedented view of the metabolic interactions within sponge-microbe symbiosis, bridging the gap between cell- and community-level knowledge.

Allelopatic effects of cyanobacteria extracts containing microcystins on Medicago sativa-Rhizobia symbiosis.

PubMed

El Khalloufi, Fatima; Oufdou, Khalid; Lahrouni, Majida; El Ghazali, Issam; Saqrane, Sanaa; Vasconcelos, Vitor; Oudra, Brahim

2011-03-01

The eutrophication of water leads to massive blooms of cyanobacteria potentially producers of highly toxic substances: cyanotoxins, especially microcystins (MC). The contamination of water used for irrigation by these toxins, can cause several adverse effects on plants and microorganisms. In this work, we report the phytotoxic effects of microcystins on the development of symbiosis between the leguminous plant Medicago sativa (Alfalfa) and rhizobia strains. The exposure of rhizobial strains to three different concentrations 0.01, 0.05 and 0.1 μg MC ml(-1) led to decrease on the bacteria growth. The strains of rhizobia Rh L1, Rh L2, Rh L3 and Rh L4 reduced their growth to, respectively, 20.85%, 20.80%, 33.19% and 25.65%. The chronic exposure of alfalfa seeds and seedlings to different MC concentrations affects the whole stages of plant development. The germination process has also been disrupted with an inhibition, which reaches 68.34% for a 22.24 μg MC ml(-1). Further, seedlings growth and photosynthetic process were also disrupted. The toxins reduced significantly the roots length and nodule formation and leads to an oxidative stress. Thus, the MCs contained in lake water and used for irrigation affect the development of symbiosis between M. sativa and Rhizobia. Copyright © 2010 Elsevier Inc. All rights reserved.

Quantifying the Contribution of Urban-Industrial Efficiency and Symbiosis to Deep Decarbonization: Impact of 637 Chinese Cities

NASA Astrophysics Data System (ADS)

Ramaswami, A.; Tong, K.; Fang, A.; Lal, R.; Nagpure, A.; Li, Y.; Yu, H.; Jiang, D.; Russell, A. G.; Shi, L.; Chertow, M.; Wang, Y.; Wang, S.

2016-12-01

Urban activities in China contribute significantly to global greenhouse gas (GHG) emissions and to local air pollution-related health risks. Co-location analysis can help inform the potential for energy- and material-exchanges across homes, businesses, infrastructure and industries co-located in cities. Such co-location dependent urban-industrial symbiosis strategies offer a new pathway toward urban energy efficiency and health that have not previously been quantified. Key examples includes the use of waste industrial heat in other co-located industries, and in residential-commercial district heating-cooling systems of cities. To quantify the impact of these strategies: (1) We develop a new data-set of 637 Chinese cities to assess the potential for efficiency and symbiosis across co-located homes, businesses, industries and the energy and construction sectors in the different cities. (2) A multi-scalar urban systems model quantifies trans-boundary CO2 impacts as well as local health benefits of these uniquely urban, co-location-dependent strategies. (3) CO2 impacts are aggregated across the 637 Chinese cities (home to 701 million people) to quantify national CO2 mitigation potential. (4) The local health benefits are modeled specific to each city and mapped geospatially to identify areas where co-benefits between GHG mitigation and health are maximized. Results: A first order conservative analysis of co-location dependent urban symbiosis indicates potential for reducing 6% of China's national total CO2 emissions in a relatively short time period, yielding a new pathway not previously considered in China's energy futures models. The magnitude of these reductions (6%) was similar in magnitude to sector specific industrial, power sector and buildings efficiency strategeies that together contributed 9% CO2 reduction aggregated across the nation. CO2 reductions mapped to the 637 cities ranged from <1% to 40%, depending upon co-location patterns, climate and other

The Role of Complement in Cnidarian-Dinoflagellate Symbiosis and Immune Challenge in the Sea Anemone Aiptasia pallida

PubMed Central

Poole, Angela Z.; Kitchen, Sheila A.; Weis, Virginia M.

2016-01-01

The complement system is an innate immune pathway that in vertebrates, is responsible for initial recognition and ultimately phagocytosis and destruction of microbes. Several complement molecules including C3, Factor B, and mannose binding lectin associated serine proteases (MASP) have been characterized in invertebrates and while most studies have focused on their conserved role in defense against pathogens, little is known about their role in managing beneficial microbes. The purpose of this study was to (1) characterize complement pathway genes in the symbiotic sea anemone Aiptasia pallida, (2) investigate the evolution of complement genes in invertebrates, and (3) examine the potential dual role of complement genes Factor B and MASP in the onset and maintenance of cnidarian-dinoflagellate symbiosis and immune challenge using qPCR based studies. The results demonstrate that A. pallida has multiple Factor B genes (Ap_Bf-1, Ap_Bf-2a, and Ap_Bf-2b) and one MASP gene (Ap_MASP). Phylogenetic analysis indicates that the evolutionary history of complement genes is complex, and there have been many gene duplications or gene loss events, even within members of the same phylum. Gene expression analyses revealed a potential role for complement in both onset and maintenance of cnidarian-dinoflagellate symbiosis and immune challenge. Specifically, Ap_Bf-1 and Ap_MASP are significantly upregulated in the light at the onset of symbiosis and in response to challenge with the pathogen Serratia marcescens suggesting that they play a role in the initial recognition of both beneficial and harmful microbes. Ap_Bf-2b in contrast, was generally downregulated during the onset and maintenance of symbiosis and in response to challenge with S. marcescens. Therefore, the exact role of Ap_Bf-2b in response to microbes remains unclear, but the results suggest that the presence of microbes leads to repressed expression. Together, these results indicate functional divergence between Ap_Bf-1

The Role of Complement in Cnidarian-Dinoflagellate Symbiosis and Immune Challenge in the Sea Anemone Aiptasia pallida.

PubMed

Poole, Angela Z; Kitchen, Sheila A; Weis, Virginia M

2016-01-01

The complement system is an innate immune pathway that in vertebrates, is responsible for initial recognition and ultimately phagocytosis and destruction of microbes. Several complement molecules including C3, Factor B, and mannose binding lectin associated serine proteases (MASP) have been characterized in invertebrates and while most studies have focused on their conserved role in defense against pathogens, little is known about their role in managing beneficial microbes. The purpose of this study was to (1) characterize complement pathway genes in the symbiotic sea anemone Aiptasia pallida, (2) investigate the evolution of complement genes in invertebrates, and (3) examine the potential dual role of complement genes Factor B and MASP in the onset and maintenance of cnidarian-dinoflagellate symbiosis and immune challenge using qPCR based studies. The results demonstrate that A. pallida has multiple Factor B genes (Ap_Bf-1, Ap_Bf-2a, and Ap_Bf-2b) and one MASP gene (Ap_MASP). Phylogenetic analysis indicates that the evolutionary history of complement genes is complex, and there have been many gene duplications or gene loss events, even within members of the same phylum. Gene expression analyses revealed a potential role for complement in both onset and maintenance of cnidarian-dinoflagellate symbiosis and immune challenge. Specifically, Ap_Bf-1 and Ap_MASP are significantly upregulated in the light at the onset of symbiosis and in response to challenge with the pathogen Serratia marcescens suggesting that they play a role in the initial recognition of both beneficial and harmful microbes. Ap_Bf-2b in contrast, was generally downregulated during the onset and maintenance of symbiosis and in response to challenge with S. marcescens. Therefore, the exact role of Ap_Bf-2b in response to microbes remains unclear, but the results suggest that the presence of microbes leads to repressed expression. Together, these results indicate functional divergence between Ap_Bf-1

Segregation in a mycorrhizal fungus alters rice growth and symbiosis-specific gene transcription.

PubMed

Angelard, Caroline; Colard, Alexandre; Niculita-Hirzel, Hélène; Croll, Daniel; Sanders, Ian R

2010-07-13

Arbuscular mycorrhizal fungi (AMF) form symbioses with the majority of plants, improving plant nutrition and diversity. Evidence exists suggesting that AMF contain populations of genetically different nucleotypes coexisting in a common cytoplasm. This potentially has two important consequences for their genetics. First, by random distribution of nuclei at spore formation, new offspring of an AMF could receive different complements of nucleotypes compared to the parent or siblings-we consider this as segregation. Second, genetic exchange between AMF would allow the mixing of nuclei, altering nucleotype diversity in new spores. Because segregation was assumed not to occur and genetic exchange has only recently been demonstrated, no attempts have been made to test whether this affects the symbiosis with plants. Here, we show that segregation occurs in the AMF Glomus intraradices and can enhance the growth of rice up to five times, even though neither parental nor crossed AMF lines induced a positive growth response. This process also resulted in an alteration of symbiosis-specific gene transcription in rice. Our results demonstrate that manipulation of AMF genetics has important consequences for the symbiotic effects on plants and could be used to enhance the growth of globally important crops. Copyright 2010 Elsevier Ltd. All rights reserved.

Medicago sativa--Sinorhizobium meliloti Symbiosis Promotes the Bioaccumulation of Zinc in Nodulated Roots.

PubMed

Zribi, Kais; Nouairi, Issam; Slama, Ines; Talbi-Zribi, Ons; Mhadhbi, Haythem

2015-01-01

In this study we investigated effects of Zn supply on germination, growth, inorganic solutes (Zn, Ca, Fe, and Mg) partitioning and nodulation of Medicago sativa This plant was cultivated with and without Zn (2 mM). Treatments were plants without (control) and with Zn tolerant strain (S532), Zn intolerant strain (S112) and 2 mM urea nitrogen fertilisation. Results showed that M. sativa germinates at rates of 50% at 2 mM Zn. For plants given nitrogen fertilisation, Zn increased plant biomass production. When grown with symbionts, Zn supply had no effect on nodulation. Moreover, plants with S112 showed a decrease of shoot and roots biomasses. However, in symbiosis with S532, an increase of roots biomass was observed. Plants in symbiosis with S. meliloti accumulated more Zn in their roots than nitrogen fertilised plants. Zn supply results in an increase of Ca concentration in roots of fertilised nitrogen plants. However, under Zn supply, Fe concentration decreased in roots and increased in nodules of plants with S112. Zn supply showed contrasting effects on Mg concentrations for plants with nitrogen fertilisation (increase) and plants with S112 (decrease). The capacity of M. sativa to accumulate Zn in their nodulated roots encouraged its use in phytostabilisation processes.

Gene Silencing of Argonaute5 Negatively Affects the Establishment of the Legume-Rhizobia Symbiosis

PubMed Central

Reyero-Saavedra, María del Rocio; Qiao, Zhenzhen; Sánchez-Correa, María del Socorro; Díaz-Pineda, M. Enrique; Covarrubias, Alejandra A.; Libault, Marc; Valdés-López, Oswaldo

2017-01-01

The establishment of the symbiosis between legumes and nitrogen-fixing rhizobia is finely regulated at the transcriptional, posttranscriptional and posttranslational levels. Argonaute5 (AGO5), a protein involved in RNA silencing, can bind both viral RNAs and microRNAs to control plant-microbe interactions and plant physiology. For instance, AGO5 regulates the systemic resistance of Arabidopsis against Potato Virus X as well as the pigmentation of soybean (Glycine max) seeds. Here, we show that AGO5 is also playing a central role in legume nodulation based on its preferential expression in common bean (Phaseolus vulgaris) and soybean roots and nodules. We also report that the expression of AGO5 is induced after 1 h of inoculation with rhizobia. Down-regulation of AGO5 gene in P. vulgaris and G. max causes diminished root hair curling, reduces nodule formation and interferes with the induction of three critical symbiotic genes: Nuclear Factor Y-B (NF-YB), Nodule Inception (NIN) and Flotillin2 (FLOT2). Our findings provide evidence that the common bean and soybean AGO5 genes play an essential role in the establishment of the symbiosis with rhizobia. PMID:29182547

Gene Silencing of Argonaute5 Negatively Affects the Establishment of the Legume-Rhizobia Symbiosis.

PubMed

Reyero-Saavedra, María Del Rocio; Qiao, Zhenzhen; Sánchez-Correa, María Del Socorro; Díaz-Pineda, M Enrique; Reyes, Jose L; Covarrubias, Alejandra A; Libault, Marc; Valdés-López, Oswaldo

2017-11-28

The establishment of the symbiosis between legumes and nitrogen-fixing rhizobia is finely regulated at the transcriptional, posttranscriptional and posttranslational levels. Argonaute5 (AGO5), a protein involved in RNA silencing, can bind both viral RNAs and microRNAs to control plant-microbe interactions and plant physiology. For instance, AGO5 regulates the systemic resistance of Arabidopsis against Potato Virus X as well as the pigmentation of soybean ( Glycine max ) seeds. Here, we show that AGO5 is also playing a central role in legume nodulation based on its preferential expression in common bean ( Phaseolus vulgaris ) and soybean roots and nodules. We also report that the expression of AGO5 is induced after 1 h of inoculation with rhizobia. Down-regulation of AGO5 gene in P. vulgaris and G. max causes diminished root hair curling, reduces nodule formation and interferes with the induction of three critical symbiotic genes: Nuclear Factor Y-B ( NF-YB ), Nodule Inception ( NIN ) and Flotillin2 ( FLOT2 ). Our findings provide evidence that the common bean and soybean AGO5 genes play an essential role in the establishment of the symbiosis with rhizobia.

Strigolactone-Induced Putative Secreted Protein 1 Is Required for the Establishment of Symbiosis by the Arbuscular Mycorrhizal Fungus Rhizophagus irregularis.

PubMed

Tsuzuki, Syusaku; Handa, Yoshihiro; Takeda, Naoya; Kawaguchi, Masayoshi

2016-04-01

Arbuscular mycorrhizal (AM) symbiosis is the most widespread association between plants and fungi. To provide novel insights into the molecular mechanisms of AM symbiosis, we screened and investigated genes of the AM fungus Rhizophagus irregularis that contribute to the infection of host plants. R. irregularis genes involved in the infection were explored by RNA-sequencing (RNA-seq) analysis. One of the identified genes was then characterized by a reverse genetic approach using host-induced gene silencing (HIGS), which causes RNA interference in the fungus via the host plant. The RNA-seq analysis revealed that 19 genes are up-regulated by both treatment with strigolactone (SL) (a plant symbiotic signal) and symbiosis. Eleven of the 19 genes were predicted to encode secreted proteins and, of these, SL-induced putative secreted protein 1 (SIS1) showed the largest induction under both conditions. In hairy roots of Medicago truncatula, SIS1 expression is knocked down by HIGS, resulting in significant suppression of colonization and formation of stunted arbuscules. These results suggest that SIS1 is a putative secreted protein that is induced in a wide spatiotemporal range including both the presymbiotic and symbiotic stages and that SIS1 positively regulates colonization of host plants by R. irregularis.

Root nodule symbiosis in Lotus japonicus drives the establishment of distinctive rhizosphere, root, and nodule bacterial communities.

PubMed

Zgadzaj, Rafal; Garrido-Oter, Ruben; Jensen, Dorthe Bodker; Koprivova, Anna; Schulze-Lefert, Paul; Radutoiu, Simona

2016-12-06

Lotus japonicus has been used for decades as a model legume to study the establishment of binary symbiotic relationships with nitrogen-fixing rhizobia that trigger root nodule organogenesis for bacterial accommodation. Using community profiling of 16S rRNA gene amplicons, we reveal that in Lotus, distinctive nodule- and root-inhabiting communities are established by parallel, rather than consecutive, selection of bacteria from the rhizosphere and root compartments. Comparative analyses of wild-type (WT) and symbiotic mutants in Nod factor receptor5 (nfr5), Nodule inception (nin) and Lotus histidine kinase1 (lhk1) genes identified a previously unsuspected role of the nodulation pathway in the establishment of different bacterial assemblages in the root and rhizosphere. We found that the loss of nitrogen-fixing symbiosis dramatically alters community structure in the latter two compartments, affecting at least 14 bacterial orders. The differential plant growth phenotypes seen between WT and the symbiotic mutants in nonsupplemented soil were retained under nitrogen-supplemented conditions that blocked the formation of functional nodules in WT, whereas the symbiosis-impaired mutants maintain an altered community structure in the nitrogen-supplemented soil. This finding provides strong evidence that the root-associated community shift in the symbiotic mutants is a direct consequence of the disabled symbiosis pathway rather than an indirect effect resulting from abolished symbiotic nitrogen fixation. Our findings imply a role of the legume host in selecting a broad taxonomic range of root-associated bacteria that, in addition to rhizobia, likely contribute to plant growth and ecological performance.

Root nodule symbiosis in Lotus japonicus drives the establishment of distinctive rhizosphere, root, and nodule bacterial communities

PubMed Central

Zgadzaj, Rafal; Garrido-Oter, Ruben; Jensen, Dorthe Bodker; Koprivova, Anna; Schulze-Lefert, Paul; Radutoiu, Simona

2016-01-01

Lotus japonicus has been used for decades as a model legume to study the establishment of binary symbiotic relationships with nitrogen-fixing rhizobia that trigger root nodule organogenesis for bacterial accommodation. Using community profiling of 16S rRNA gene amplicons, we reveal that in Lotus, distinctive nodule- and root-inhabiting communities are established by parallel, rather than consecutive, selection of bacteria from the rhizosphere and root compartments. Comparative analyses of wild-type (WT) and symbiotic mutants in Nod factor receptor5 (nfr5), Nodule inception (nin) and Lotus histidine kinase1 (lhk1) genes identified a previously unsuspected role of the nodulation pathway in the establishment of different bacterial assemblages in the root and rhizosphere. We found that the loss of nitrogen-fixing symbiosis dramatically alters community structure in the latter two compartments, affecting at least 14 bacterial orders. The differential plant growth phenotypes seen between WT and the symbiotic mutants in nonsupplemented soil were retained under nitrogen-supplemented conditions that blocked the formation of functional nodules in WT, whereas the symbiosis-impaired mutants maintain an altered community structure in the nitrogen-supplemented soil. This finding provides strong evidence that the root-associated community shift in the symbiotic mutants is a direct consequence of the disabled symbiosis pathway rather than an indirect effect resulting from abolished symbiotic nitrogen fixation. Our findings imply a role of the legume host in selecting a broad taxonomic range of root-associated bacteria that, in addition to rhizobia, likely contribute to plant growth and ecological performance. PMID:27864511

New insights into the regulation of aquaporins by the arbuscular mycorrhizal symbiosis in maize plants under drought stress and possible implications for plant performance.

PubMed

Bárzana, Gloria; Aroca, Ricardo; Bienert, Gerd Patrick; Chaumont, François; Ruiz-Lozano, Juan Manuel

2014-04-01

The relationship between modulation by arbuscular mycorrhizae (AM) of aquaporin expression in the host plant and changes in root hydraulic conductance, plant water status, and performance under stressful conditions is not well known. This investigation aimed to elucidate how the AM symbiosis modulates the expression of the whole set of aquaporin genes in maize plants under different growing and drought stress conditions, as well as to characterize some of these aquaporins in order to shed further light on the molecules that may be involved in the mycorrhizal responses to drought. The AM symbiosis regulated a wide number of aquaporins in the host plant, comprising members of the different aquaporin subfamilies. The regulation of these genes depends on the watering conditions and the severity of the drought stress imposed. Some of these aquaporins can transport water and also other molecules which are of physiological importance for plant performance. AM plants grew and developed better than non-AM plants under the different conditions assayed. Thus, for the first time, this study relates the well-known better performance of AM plants under drought stress to not only the water movement in their tissues but also the mobilization of N compounds, glycerol, signaling molecules, or metalloids with a role in abiotic stress tolerance. Future studies should elucidate the specific function of each aquaporin isoform regulated by the AM symbiosis in order to shed further light on how the symbiosis alters the plant fitness under stressful conditions.

A Sinorhizobium meliloti RpoH-Regulated Gene Is Involved in Iron-Sulfur Protein Metabolism and Effective Plant Symbiosis under Intrinsic Iron Limitation.

PubMed

Sasaki, Shohei; Minamisawa, Kiwamu; Mitsui, Hisayuki

2016-09-01

In Sinorhizobium meliloti, RpoH-type sigma factors have a global impact on gene expression during heat shock and play an essential role in symbiosis with leguminous plants. Using mutational analysis of a set of genes showing highly RpoH-dependent expression during heat shock, we identified a gene indispensable for effective symbiosis. This gene, designated sufT, was located downstream of the sufBCDS homologs that specify the iron-sulfur (Fe/S) cluster assembly pathway. The identified transcription start site was preceded by an RpoH-dependent promoter consensus sequence. SufT was related to a conserved protein family of unknown molecular function, of which some members are involved in Fe/S cluster metabolism in diverse organisms. A sufT mutation decreased bacterial growth in both rich and minimal media, tolerance to stresses such as iron starvation, and activities of some Fe/S cluster-dependent enzymes. These results support the involvement of SufT in SUF (sulfur mobilization) system-mediated Fe/S protein metabolism. Furthermore, we isolated spontaneous pseudorevertants of the sufT mutant with partially recovered growth; each of them had a mutation in rirA This gene encodes a global iron regulator whose loss increases the intracellular iron content. Deletion of rirA in the original sufT mutant improved growth and restored Fe/S enzyme activities and effective symbiosis. These results suggest that enhanced iron availability compensates for the lack of SufT in the maintenance of Fe/S proteins. Although RpoH-type sigma factors of the RNA polymerase are present in diverse proteobacteria, their role as global regulators of protein homeostasis has been studied mainly in the enteric gammaproteobacterium Escherichia coli In the soil alphaproteobacterium Sinorhizobium meliloti, the rpoH mutations have a strong impact on symbiosis with leguminous plants. We found that sufT is a unique member of the S. meliloti RpoH regulon; sufT contributes to Fe/S protein metabolism and

Solar astrophysics - Ghettosis from, or symbiosis with, stellar and galactic astrophysics

NASA Technical Reports Server (NTRS)

Pecker, J.-C.; Thomas, R. N.

1976-01-01

The purpose of the paper is to show how the solar-stellar symbiotic approach has led to the modeling of a star as a concentration of matter and energy. By 'solar-stellar symbiosis' is meant the philosophy of investigation according to which one asks what change in our general understanding of stellar structure and of stellar spectroscopic diagnostics is required to satisfy both the sun and an unusual star when, for example, some feature of an unusual star is discovered. The evolution of stellar models is traced, from walled, thermodynamic-equilibrium models to de-isolated models featuring transition zones and nonlocal thermodynamic equilibrium.

Implication of the host TGFβ pathway in the onset of symbiosis between larvae of the coral Fungia scutaria and the dinoflagellate Symbiodinium sp. (clade C1f)

NASA Astrophysics Data System (ADS)

Berthelier, Jérémy; Schnitzler, Christine E.; Wood-Charlson, Elisha M.; Poole, Angela Z.; Weis, Virginia M.; Detournay, Olivier

2017-12-01

Dinoflagellate-cnidarian associations form both the trophic and structural foundation of coral-reef ecosystems. Previous studies have highlighted the role of host innate immunity in regulation of these partnerships. This study reveals the presence of a transforming growth factor beta (TGFβ) in the coral Fungia scutaria that clusters with TGFβ sensu stricto (ss) from other animals. In functional studies of F. scutaria larvae, we show that (1) TGFβ ss mRNA is expressed during early stages of development prior to the onset of symbiosis; (2) apparent interference of the TGFβ pathway impairs the onset of symbiosis; and (3) this effect is associated with an increase of cytotoxic nitric oxide secretion, an immune response. This work highlights the importance of the TGFβ pathway in early life-history stages of corals by suggesting that its inhibition impacts the onset of symbiosis.

The Impact of Nitrogen Limitation and Mycorrhizal Symbiosis on Aspen Tree Growth and Development

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tran, Bich Thi Ngoc

Nitrogen deficiency is the most common and widespread nutritional deficiency affecting plants worldwide. Ectromycorrhizal symbiosis involves the beneficial interaction of plants with soil fungi and plays a critical role in nutrient cycling, including the uptake of nitrogen from the environment. The main goal of this study is to understand how limiting nitrogen in the presence or absence of an ectomycorrhizal fungi, Laccaria bicolor, affects the health of aspen trees, Populus temuloides.

The role of fungal symbiosis in the adaptation of plants to high stress environments

USGS Publications Warehouse

Rodriguez, Russell J.; Redman, Regina S.; Henson, Joan M.

2004-01-01

All plants studied in natural ecosystemsare symbiotic with fungi that either resideentirely (endophytes) or partially(mycorrhizae) within plants. Thesesymbioses appear to adapt to biotic andabiotic stresses and may be responsible forthe survival of both plant hosts and fungalsymbionts in high stress habitats. Here wedescribe the role of symbiotic fungi inplant stress tolerance and present astrategy based on adaptive symbiosis topotentially mitigate the impacts of globalchange on plant communities.

X-ray microanalytical studies of mineral elements in the tripartite symbiosis between lima bean, N2-fixing bacteria and mycorrhizal fungi.

PubMed

Rodak, Bruna Wurr; Freitas, Douglas Siqueira; Bamberg, Soraya Marx; Carneiro, Marco Aurélio Carbone; Guilherme, Luiz Roberto Guimarães

2017-01-01

The symbiosis between legumes, arbuscular mycorrhizal (AM) fungi, and N 2 -fixing bacteria (NFB) provides mutual nutritional gains. However, assessing the nutritional status of the microorganisms is a difficult task. A methodology that could assess this status, in situ, could assist managing these organisms in agriculture. This study used X-ray microanalyses to quantify and locate mineral elements in structures formed in a tripartite symbiosis. Lima bean (Phaseolus lunatus L. Walp) was cultivated in pots under greenhouse conditions, to which we have added AM fungal isolates (Glomus macrocarpum and Acaulospora colombiana) and NFB (Bradyrhizobium japonicum) inocula. Uninoculated control plants were also included. Symbionts were evaluated at the onset of flowering. Quantification of the mineral elements in the symbiotic components was performed using energy dispersive X-ray spectroscopy (EDX) and a scanning electron microscopy (SEM) was used to identify structures. EDX analysis detected 13 elements with the most abundant being N, Ca, and Se, occurring in all tissues, Fe in roots, Ni and Al in epidermis and P and Mo in nodules. Elemental quantification in fungal structures was not possible. The distribution of elements was related to their symbiotic function. X-ray microanalysis can be efficiently applied for nutritional diagnosis in tripartite symbiosis. Copyright © 2016 Elsevier B.V. All rights reserved.

Arbuscular Mycorrhizal Symbiosis Modulates Antioxidant Response and Ion Distribution in Salt-Stressed Elaeagnus angustifolia Seedlings.

PubMed

Chang, Wei; Sui, Xin; Fan, Xiao-Xu; Jia, Ting-Ting; Song, Fu-Qiang

2018-01-01

Elaeagnus angustifolia L. is a drought-resistant species. Arbuscular mycorrhizal symbiosis is considered to be a bio-ameliorator of saline soils that can improve salinity tolerance in plants. The present study investigated the effects of inoculation with the arbuscular mycorrhizal fungus Rhizophagus irregularis on the biomass, antioxidant enzyme activities, and root, stem, and leaf ion accumulation of E. angustifolia seedlings grown during salt stress conditions. Salt-stressed mycorrhizal seedlings produced greater root, stem, and leaf biomass than the uninoculated stressed seedlings. In addition, the seedlings colonized by R. irregularis showed notably higher activities of superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX) in the leaves of the mycorrhizal seedlings in response to salinity compared to those of the non-mycorrhizal seedlings. Mycorrhizal seedlings not only significantly increased their ability to acquire K + , Ca 2+ , and Mg 2+ , but also maintained higher K + :Na + ratios in the leaves and lower Ca 2+ :Mg 2+ ratios than non-mycorrhizal seedlings during salt stress. These results suggest that the salt tolerance of E. angustifolia seedlings could be enhanced by R. irregularis. The arbuscular mycorrhizal symbiosis could be a promising method to restore and utilize salt-alkaline land in northern China.

The Irreversible Loss of a Decomposition Pathway Marks the Single Origin of an Ectomycorrhizal Symbiosis

PubMed Central

Wolfe, Benjamin E.; Tulloss, Rodham E.; Pringle, Anne

2012-01-01

Microbial symbioses have evolved repeatedly across the tree of life, but the genetic changes underlying transitions to symbiosis are largely unknown, especially for eukaryotic microbial symbionts. We used the genus Amanita, an iconic group of mushroom-forming fungi engaged in ectomycorrhizal symbioses with plants, to identify both the origins and potential genetic changes maintaining the stability of this mutualism. A multi-gene phylogeny reveals one origin of the symbiosis within Amanita, with a single transition from saprotrophic decomposition of dead organic matter to biotrophic dependence on host plants for carbon. Associated with this transition are the losses of two cellulase genes, each of which plays a critical role in extracellular decomposition of organic matter. However a third gene, which acts at later stages in cellulose decomposition, is retained by many, but not all, ectomycorrhizal species. Experiments confirm that symbiotic Amanita species have lost the ability to grow on complex organic matter and have therefore lost the capacity to live in forest soils without carbon supplied by a host plant. Irreversible losses of decomposition pathways are likely to play key roles in the evolutionary stability of these ubiquitous mutualisms. PMID:22815710

A Transient Exposure to Symbiosis-Competent Bacteria Induces Light Organ Morphogenesis in the Host Squid.

PubMed

Doino, J A; McFall-Ngai, M J

1995-12-01

Recent studies of the symbiotic association between the Hawaiian sepiolid squid Euprymna scolopes and the luminous bacterium Vibrio fischeri have shown that colonization of juvenile squid with symbiosis-competent bacteria induces morphogenetic changes of the light organ. These changes occur over a 4-day period and include cell death and tissue regression of the external ciliated epithelium. In the absence of bacterial colonization, morphogenesis does not occur. To determine whether the bacteria must be present throughout the morphogenetic process, we used the antibiotic chloramphenicol to clear the light organ of bacteria at various times during the initial colonization. We provide evidence in this study that a transient, 12-hour exposure to symbiosis-competent bacteria is necessary and sufficient to induce tissue regression in the light organ over the next several days. Further, we show that successful entrance into the light organ is necessary to induce morphogenesis, suggesting that induction results from bacterial interaction with internal crypt cells and not with the external ciliated epithelium. Finally, no difference in development was observed when the light organ was colonized by a mutant strain of V. fischeri that did not produce autoinducer, a potential light organ morphogen.

Making the Most of Omics for Symbiosis Research

PubMed Central

Chaston, J.; Douglas, A.E.

2012-01-01

Omics, including genomics, proteomics and metabolomics, enable us to explain symbioses in terms of the underlying molecules and their interactions. The central task is to transform molecular catalogs of genes, metabolites etc. into a dynamic understanding of symbiosis function. We review four exemplars of omics studies that achieve this goal, through defined biological questions relating to metabolic integration and regulation of animal-microbial symbioses, the genetic autonomy of bacterial symbionts, and symbiotic protection of animal hosts from pathogens. As omic datasets become increasingly complex, computationally-sophisticated downstream analyses are essential to reveal interactions not evident to visual inspection of the data. We discuss two approaches, phylogenomics and transcriptional clustering, that can divide the primary output of omics studies – long lists of factors – into manageable subsets, and we describe how they have been applied to analyze large datasets and generate testable hypotheses. PMID:22983030

A diverse host thrombospondin-type-1 repeat protein repertoire promotes symbiont colonization during establishment of cnidarian-dinoflagellate symbiosis.

PubMed

Neubauer, Emilie-Fleur; Poole, Angela Z; Neubauer, Philipp; Detournay, Olivier; Tan, Kenneth; Davy, Simon K; Weis, Virginia M

2017-05-08

The mutualistic endosymbiosis between cnidarians and dinoflagellates is mediated by complex inter-partner signaling events, where the host cnidarian innate immune system plays a crucial role in recognition and regulation of symbionts. To date, little is known about the diversity of thrombospondin-type-1 repeat (TSR) domain proteins in basal metazoans or their potential role in regulation of cnidarian-dinoflagellate mutualisms. We reveal a large and diverse repertoire of TSR proteins in seven anthozoan species, and show that in the model sea anemone Aiptasia pallida the TSR domain promotes colonization of the host by the symbiotic dinoflagellate Symbiodinium minutum . Blocking TSR domains led to decreased colonization success, while adding exogenous TSRs resulted in a 'super colonization'. Furthermore, gene expression of TSR proteins was highest at early time-points during symbiosis establishment. Our work characterizes the diversity of cnidarian TSR proteins and provides evidence that these proteins play an important role in the establishment of cnidarian-dinoflagellate symbiosis.

From root to fruit: RNA-Seq analysis shows that arbuscular mycorrhizal symbiosis may affect tomato fruit metabolism.

PubMed

Zouari, Inès; Salvioli, Alessandra; Chialva, Matteo; Novero, Mara; Miozzi, Laura; Tenore, Gian Carlo; Bagnaresi, Paolo; Bonfante, Paola

2014-03-21

Tomato (Solanum lycopersicum) establishes a beneficial symbiosis with arbuscular mycorrhizal (AM) fungi. The formation of the mycorrhizal association in the roots leads to plant-wide modulation of gene expression. To understand the systemic effect of the fungal symbiosis on the tomato fruit, we used RNA-Seq to perform global transcriptome profiling on Moneymaker tomato fruits at the turning ripening stage. Fruits were collected at 55 days after flowering, from plants colonized with Funneliformis mosseae and from control plants, which were fertilized to avoid responses related to nutrient deficiency. Transcriptome analysis identified 712 genes that are differentially expressed in fruits from mycorrhizal and control plants. Gene Ontology (GO) enrichment analysis of these genes showed 81 overrepresented functional GO classes. Up-regulated GO classes include photosynthesis, stress response, transport, amino acid synthesis and carbohydrate metabolism functions, suggesting a general impact of fungal symbiosis on primary metabolisms and, particularly, on mineral nutrition. Down-regulated GO classes include cell wall, metabolism and ethylene response pathways. Quantitative RT-PCR validated the RNA-Seq results for 12 genes out of 14 when tested at three fruit ripening stages, mature green, breaker and turning. Quantification of fruit nutraceutical and mineral contents produced values consistent with the expression changes observed by RNA-Seq analysis. This RNA-Seq profiling produced a novel data set that explores the intersection of mycorrhization and fruit development. We found that the fruits of mycorrhizal plants show two transcriptomic "signatures": genes characteristic of a climacteric fleshy fruit, and genes characteristic of mycorrhizal status, like phosphate and sulphate transporters. Moreover, mycorrhizal plants under low nutrient conditions produce fruits with a nutrient content similar to those from non-mycorrhizal plants under high nutrient conditions

Symbiosis between nitrogen-fixing bacteria and Medicago truncatula is not significantly affected by silver and silver sulfide nanomaterials.

PubMed

Judy, Jonathan D; Kirby, Jason K; McLaughlin, Mike J; McNear, David; Bertsch, Paul M

2016-07-01

Silver (Ag) engineered nanomaterials (ENMs) are being released into waste streams and are being discharged, largely as Ag2S aged-ENMs (a-ENMs), into agroecosystems receiving biosolids amendments. Recent research has demonstrated that biosolids containing an environmentally relevant mixture of ZnO, TiO2, and Ag ENMs and their transformation products, including Ag2S a-ENMs, disrupted the symbiosis between nitrogen-fixing bacteria and legumes. However, this study was unable to unequivocally determine which ENM or combination of ENMs and a-ENMs was responsible for the observed inhibition. Here, we examined further the effects of polyvinylpyrollidone (PVP) coated pristine Ag ENMs (PVP-Ag), Ag2S a-ENMs, and soluble Ag (as AgSO4) at 1, 10, and 100 mg Ag kg(-1) on the symbiosis between the legume Medicago truncatula and the nitrogen-fixing bacterium, Sinorhizobium melliloti in biosolids-amended soil. Nodulation frequency, nodule function, glutathione reductase production, and biomass were not significantly affected by any of the Ag treatments, even at 100 mg kg(-1), a concentration analogous to a worst-case scenario resulting from long-term, repeated biosolids amendments. Our results provide additional evidence that the disruption of the symbiosis between nitrogen-fixing bacteria and legumes in response to a mixture of ENMs in biosolids-amended soil reported previously may not be attributable to Ag ENMs or their transformation end-products. We anticipate these findings will provide clarity to regulators and industry regarding potential unintended consequences to terrestrial ecosystems resulting from of the use of Ag ENMs in consumer products. Copyright © 2016 Elsevier Ltd. All rights reserved.

Bacterial Molecular Signals in the Sinorhizobium fredii-Soybean Symbiosis

PubMed Central

López-Baena, Francisco J.; Ruiz-Sainz, José E.; Rodríguez-Carvajal, Miguel A.; Vinardell, José M.

2016-01-01

Sinorhizobium (Ensifer) fredii (S. fredii) is a rhizobial species exhibiting a remarkably broad nodulation host-range. Thus, S. fredii is able to effectively nodulate dozens of different legumes, including plants forming determinate nodules, such as the important crops soybean and cowpea, and plants forming indeterminate nodules, such as Glycyrrhiza uralensis and pigeon-pea. This capacity of adaptation to different symbioses makes the study of the molecular signals produced by S. fredii strains of increasing interest since it allows the analysis of their symbiotic role in different types of nodule. In this review, we analyze in depth different S. fredii molecules that act as signals in symbiosis, including nodulation factors, different surface polysaccharides (exopolysaccharides, lipopolysaccharides, cyclic glucans, and K-antigen capsular polysaccharides), and effectors delivered to the interior of the host cells through a symbiotic type 3 secretion system. PMID:27213334

Genome of an arbuscular mycorrhizal fungus provides insight into the oldest plant symbiosis.

PubMed

Tisserant, Emilie; Malbreil, Mathilde; Kuo, Alan; Kohler, Annegret; Symeonidi, Aikaterini; Balestrini, Raffaella; Charron, Philippe; Duensing, Nina; Frei dit Frey, Nicolas; Gianinazzi-Pearson, Vivienne; Gilbert, Luz B; Handa, Yoshihiro; Herr, Joshua R; Hijri, Mohamed; Koul, Raman; Kawaguchi, Masayoshi; Krajinski, Franziska; Lammers, Peter J; Masclaux, Frederic G; Murat, Claude; Morin, Emmanuelle; Ndikumana, Steve; Pagni, Marco; Petitpierre, Denis; Requena, Natalia; Rosikiewicz, Pawel; Riley, Rohan; Saito, Katsuharu; San Clemente, Hélène; Shapiro, Harris; van Tuinen, Diederik; Bécard, Guillaume; Bonfante, Paola; Paszkowski, Uta; Shachar-Hill, Yair Y; Tuskan, Gerald A; Young, J Peter W; Young, Peter W; Sanders, Ian R; Henrissat, Bernard; Rensing, Stefan A; Grigoriev, Igor V; Corradi, Nicolas; Roux, Christophe; Martin, Francis

2013-12-10

The mutualistic symbiosis involving Glomeromycota, a distinctive phylum of early diverging Fungi, is widely hypothesized to have promoted the evolution of land plants during the middle Paleozoic. These arbuscular mycorrhizal fungi (AMF) perform vital functions in the phosphorus cycle that are fundamental to sustainable crop plant productivity. The unusual biological features of AMF have long fascinated evolutionary biologists. The coenocytic hyphae host a community of hundreds of nuclei and reproduce clonally through large multinucleated spores. It has been suggested that the AMF maintain a stable assemblage of several different genomes during the life cycle, but this genomic organization has been questioned. Here we introduce the 153-Mb haploid genome of Rhizophagus irregularis and its repertoire of 28,232 genes. The observed low level of genome polymorphism (0.43 SNP per kb) is not consistent with the occurrence of multiple, highly diverged genomes. The expansion of mating-related genes suggests the existence of cryptic sex-related processes. A comparison of gene categories confirms that R. irregularis is close to the Mucoromycotina. The AMF obligate biotrophy is not explained by genome erosion or any related loss of metabolic complexity in central metabolism, but is marked by a lack of genes encoding plant cell wall-degrading enzymes and of genes involved in toxin and thiamine synthesis. A battery of mycorrhiza-induced secreted proteins is expressed in symbiotic tissues. The present comprehensive repertoire of R. irregularis genes provides a basis for future research on symbiosis-related mechanisms in Glomeromycota.

Functional significance of genetically different symbiotic algae Symbiodinium in a coral reef symbiosis.

PubMed

Loram, J E; Trapido-Rosenthal, H G; Douglas, A E

2007-11-01

The giant sea anemone Condylactis gigantea associates with members of two clades of the dinoflagellate alga Symbiodinium, either singly or in mixed infection, as revealed by clade-specific quantitative polymerase chain reaction of large subunit ribosomal DNA. To explore the functional significance of this molecular variation, the fate of photosynthetically fixed carbon was investigated by (14)C radiotracer experiments. Symbioses with algae of clades A and B released ca. 30-40% of fixed carbon to the animal tissues. Incorporation into the lipid fraction and the low molecular weight fraction dominated by amino acids was significantly higher in symbioses with algae of clade A than of clade B, suggesting that the genetically different algae in C. gigantea are not functionally equivalent. Symbioses with mixed infections yielded intermediate values, such that this functional trait of the symbiosis can be predicted from the traits of the contributing algae. Coral and sea anemone symbioses with Symbiodinium break down at elevated temperature, a process known as 'coral bleaching'. The functional response of the C. gigantea symbiosis to heat stress varied between the algae of clades A and B, with particularly depressed incorporation of photosynthetic carbon into lipid of the clade B algae, which are more susceptible to high temperature than the algae of clade A. This study provides a first exploration of how the core symbiotic function of photosynthate transfer to the host varies with the genotype of Symbiodinium, an algal symbiont which underpins corals and, hence, coral reef ecosystems.

Genome of an arbuscular mycorrhizal fungus provides insight into the oldest plant symbiosis

PubMed Central

Tisserant, Emilie; Malbreil, Mathilde; Kuo, Alan; Kohler, Annegret; Symeonidi, Aikaterini; Balestrini, Raffaella; Charron, Philippe; Duensing, Nina; Frei dit Frey, Nicolas; Gianinazzi-Pearson, Vivienne; Gilbert, Luz B.; Handa, Yoshihiro; Herr, Joshua R.; Hijri, Mohamed; Koul, Raman; Kawaguchi, Masayoshi; Krajinski, Franziska; Lammers, Peter J.; Masclaux, Frederic G.; Murat, Claude; Morin, Emmanuelle; Ndikumana, Steve; Pagni, Marco; Petitpierre, Denis; Requena, Natalia; Rosikiewicz, Pawel; Riley, Rohan; Saito, Katsuharu; San Clemente, Hélène; Shapiro, Harris; van Tuinen, Diederik; Bécard, Guillaume; Bonfante, Paola; Paszkowski, Uta; Shachar-Hill, Yair Y.; Tuskan, Gerald A.; Young, J. Peter W.; Sanders, Ian R.; Henrissat, Bernard; Rensing, Stefan A.; Grigoriev, Igor V.; Corradi, Nicolas; Roux, Christophe; Martin, Francis

2013-01-01

The mutualistic symbiosis involving Glomeromycota, a distinctive phylum of early diverging Fungi, is widely hypothesized to have promoted the evolution of land plants during the middle Paleozoic. These arbuscular mycorrhizal fungi (AMF) perform vital functions in the phosphorus cycle that are fundamental to sustainable crop plant productivity. The unusual biological features of AMF have long fascinated evolutionary biologists. The coenocytic hyphae host a community of hundreds of nuclei and reproduce clonally through large multinucleated spores. It has been suggested that the AMF maintain a stable assemblage of several different genomes during the life cycle, but this genomic organization has been questioned. Here we introduce the 153-Mb haploid genome of Rhizophagus irregularis and its repertoire of 28,232 genes. The observed low level of genome polymorphism (0.43 SNP per kb) is not consistent with the occurrence of multiple, highly diverged genomes. The expansion of mating-related genes suggests the existence of cryptic sex-related processes. A comparison of gene categories confirms that R. irregularis is close to the Mucoromycotina. The AMF obligate biotrophy is not explained by genome erosion or any related loss of metabolic complexity in central metabolism, but is marked by a lack of genes encoding plant cell wall-degrading enzymes and of genes involved in toxin and thiamine synthesis. A battery of mycorrhiza-induced secreted proteins is expressed in symbiotic tissues. The present comprehensive repertoire of R. irregularis genes provides a basis for future research on symbiosis-related mechanisms in Glomeromycota. PMID:24277808

An integrated functional approach to dissect systemic responses in maize to arbuscular mycorrhizal symbiosis.

PubMed

Gerlach, Nina; Schmitz, Jessica; Polatajko, Aleksandra; Schlüter, Urte; Fahnenstich, Holger; Witt, Sandra; Fernie, Alisdair R; Uroic, Kalle; Scholz, Uwe; Sonnewald, Uwe; Bucher, Marcel

2015-08-01

Most terrestrial plants benefit from the symbiosis with arbuscular mycorrhizal fungi (AMF) mainly under nutrient-limited conditions. Here the crop plant Zea mays was grown with and without AMF in a bi-compartmented system separating plant and phosphate (Pi) source by a hyphae-permeable membrane. Thus, Pi was preferentially taken up via the mycorrhizal Pi uptake pathway while other nutrients were ubiquitously available. To study systemic effects of mycorrhizal Pi uptake on leaf status, leaves of these plants that display an increased biomass in the presence of AMF were subjected to simultaneous ionomic, transcriptomic and metabolomic analyses. We observed robust changes of the leaf elemental composition, that is, increase of P, S and Zn and decrease of Mn, Co and Li concentration in mycorrhizal plants. Although changes in anthocyanin and lipid metabolism point to an improved P status, a global increase in C versus N metabolism highlights the redistribution of metabolic pools including carbohydrates and amino acids. Strikingly, an induction of systemic defence gene expression and concomitant accumulation of secondary metabolites such as the terpenoids alpha- and beta-amyrin suggest priming of mycorrhizal maize leaves as a mycorrhiza-specific response. This work emphasizes the importance of AM symbiosis for the physiological status of plant leaves and could lead to strategies for optimized breeding of crop species with high growth potential. © 2015 John Wiley & Sons Ltd.

Arbuscular Mycorrhizal Symbiosis Modulates Antioxidant Response and Ion Distribution in Salt-Stressed Elaeagnus angustifolia Seedlings

PubMed Central

Chang, Wei; Sui, Xin; Fan, Xiao-Xu; Jia, Ting-Ting; Song, Fu-Qiang

2018-01-01

Elaeagnus angustifolia L. is a drought-resistant species. Arbuscular mycorrhizal symbiosis is considered to be a bio-ameliorator of saline soils that can improve salinity tolerance in plants. The present study investigated the effects of inoculation with the arbuscular mycorrhizal fungus Rhizophagus irregularis on the biomass, antioxidant enzyme activities, and root, stem, and leaf ion accumulation of E. angustifolia seedlings grown during salt stress conditions. Salt-stressed mycorrhizal seedlings produced greater root, stem, and leaf biomass than the uninoculated stressed seedlings. In addition, the seedlings colonized by R. irregularis showed notably higher activities of superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX) in the leaves of the mycorrhizal seedlings in response to salinity compared to those of the non-mycorrhizal seedlings. Mycorrhizal seedlings not only significantly increased their ability to acquire K+, Ca2+, and Mg2+, but also maintained higher K+:Na+ ratios in the leaves and lower Ca2+:Mg2+ ratios than non-mycorrhizal seedlings during salt stress. These results suggest that the salt tolerance of E. angustifolia seedlings could be enhanced by R. irregularis. The arbuscular mycorrhizal symbiosis could be a promising method to restore and utilize salt-alkaline land in northern China. PMID:29675008

A Nostoc punctiforme Sugar Transporter Necessary to Establish a Cyanobacterium-Plant Symbiosis1[C][W

PubMed Central

Ekman, Martin; Picossi, Silvia; Campbell, Elsie L.; Meeks, John C.; Flores, Enrique

2013-01-01

In cyanobacteria-plant symbioses, the symbiotic nitrogen-fixing cyanobacterium has low photosynthetic activity and is supplemented by sugars provided by the plant partner. Which sugars and cyanobacterial sugar uptake mechanism(s) are involved in the symbiosis, however, is unknown. Mutants of the symbiotically competent, facultatively heterotrophic cyanobacterium Nostoc punctiforme were constructed bearing a neomycin resistance gene cassette replacing genes in a putative sugar transport gene cluster. Results of transport activity assays using 14C-labeled fructose and glucose and tests of heterotrophic growth with these sugars enabled the identification of an ATP-binding cassette-type transporter for fructose (Frt), a major facilitator permease for glucose (GlcP), and a porin needed for the optimal uptake of both fructose and glucose. Analysis of green fluorescent protein fluorescence in strains of N. punctiforme bearing frt::gfp fusions showed high expression in vegetative cells and akinetes, variable expression in hormogonia, and no expression in heterocysts. The symbiotic efficiency of N. punctiforme sugar transport mutants was investigated by testing their ability to infect a nonvascular plant partner, the hornwort Anthoceros punctatus. Strains that were specifically unable to transport glucose did not infect the plant. These results imply a role for GlcP in establishing symbiosis under the conditions used in this work. PMID:23463784

The importance of integration and scale in the arbuscular mycorrhizal symbiosis.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miller, R. M.; Kling, M.; Environmental Research

The arbuscular mycorrhizal (AM) fungus contributes to system processes and functions at various hierarchical organizational levels, through their establishment of linkages and feedbacks between whole-plants and nutrient cycles. Even though these fungal mediated feedbacks and linkages involve lower-organizational level processes (e.g. photo-assimilate partitioning, interfacial assimilate uptake and transport mechanisms, intraradical versus extraradical fungal growth), they influence higher-organizational scales that affect community and ecosystem behavior (e.g. whole-plant photosynthesis, biodiversity, nutrient and carbon cycling, soil structure). Hence, incorporating AM fungi into research directed at understanding many of the diverse environmental issues confronting society will require knowledge of how these fungi respond tomore » or initiate changes in vegetation dynamics, soil fertility or both. Within the last few years, the rapid advancement in the development of analytical tools has increased the resolution by which we are able to quantify the mycorrhizal symbiosis. It is important that these tools are applied within a conceptual framework that is temporally and spatially relevant to fungus and host. Unfortunately, many of the studies being conducted on the mycorrhizal symbiosis at lower organizational scales are concerned with questions directed solely at understanding fungus or host without awareness of what the plant physiologist or ecologist needs for integrating the mycorrhizal association into larger organizational scales or process levels. We show by using the flow of C from plant-to-fungus-to-soil, that through thoughtful integration, we have the ability to bridge different organizational scales. Thus, an essential need of mycorrhizal research is not only to better integrate the various disciplines of mycorrhizal research, but also to identify those relevant links and scales needing further investigation for understanding the larger

Adapted to change: The rapid development of symbiosis in newly settled, fast-maturing chemosymbiotic mussels in the deep sea.

PubMed

Laming, Sven R; Duperron, Sébastien; Gaudron, Sylvie M; Hilário, Ana; Cunha, Marina R

2015-12-01

Symbioses between microbiota and marine metazoa occur globally at chemosynthetic habitats facing imminent threat from anthropogenic disturbance, yet little is known concerning the role of symbiosis during early development in chemosymbiotic metazoans: a critical period in any benthic species' lifecycle. The emerging symbiosis of Idas (sensu lato) simpsoni mussels undergoing development is assessed over a post-larval-to-adult size spectrum using histology and fluorescence in situ hybridisation (FISH). Post-larval development shows similarities to that of both heterotrophic and chemosymbiotic mussels. Data from newly settled specimens confirm aposymbiotic, planktotrophic larval development. Sulphur-oxidising (SOX) symbionts subsequently colonise multiple exposed, non-ciliated epithelia shortly after metamorphosis, but only become abundant on gills as these expand with greater host size. This wide-spread bathymodiolin recorded from sulphidic wood, bone and cold-seep habitats, displays a suite of adaptive traits that could buffer against anthropogenic disturbance. Copyright © 2015 Elsevier Ltd. All rights reserved.

Mycosporine-like amino acids in the zooxanthella-ciliate symbiosis Maristentor dinoferus.

PubMed

Sommaruga, Ruben; Whitehead, Kenia; Shick, J Malcolm; Lobban, Christopher S

2006-06-01

Coral reef organisms living in mutualistic symbioses with phototrophic dinoflagellates are widespread in shallow UV-transparent waters. Maristentor dinoferus is a recently discovered species of marine benthic ciliate that hosts symbiotic dinoflagellates of the genus Symbiodinium. In this study, we tested this ciliate for the occurrence of mycosporine-like amino acids, a family of secondary metabolites that minimize damage from exposure to solar UV radiation by direct screening. Using high-performance liquid chromatography and liquid chromatography coupled to mass spectrometry, five mycosporine-like amino acids (shinorine, palythenic acid, palythine, mycosporine-2-glycine, and porphyra-334) were identified in aqueous methanolic extracts of the symbiosis. This is the first report of mycosporine-like amino acids in a marine ciliate.

A diverse host thrombospondin-type-1 repeat protein repertoire promotes symbiont colonization during establishment of cnidarian-dinoflagellate symbiosis

PubMed Central

Neubauer, Emilie-Fleur; Poole, Angela Z; Neubauer, Philipp; Detournay, Olivier; Tan, Kenneth; Davy, Simon K; Weis, Virginia M

2017-01-01

The mutualistic endosymbiosis between cnidarians and dinoflagellates is mediated by complex inter-partner signaling events, where the host cnidarian innate immune system plays a crucial role in recognition and regulation of symbionts. To date, little is known about the diversity of thrombospondin-type-1 repeat (TSR) domain proteins in basal metazoans or their potential role in regulation of cnidarian-dinoflagellate mutualisms. We reveal a large and diverse repertoire of TSR proteins in seven anthozoan species, and show that in the model sea anemone Aiptasia pallida the TSR domain promotes colonization of the host by the symbiotic dinoflagellate Symbiodinium minutum. Blocking TSR domains led to decreased colonization success, while adding exogenous TSRs resulted in a ‘super colonization’. Furthermore, gene expression of TSR proteins was highest at early time-points during symbiosis establishment. Our work characterizes the diversity of cnidarian TSR proteins and provides evidence that these proteins play an important role in the establishment of cnidarian-dinoflagellate symbiosis. DOI: http://dx.doi.org/10.7554/eLife.24494.001 PMID:28481198

Coral life history and symbiosis: Functional genomic resources for two reef building Caribbean corals, Acropora palmata and Montastraea faveolata

PubMed Central

Schwarz, Jodi A; Brokstein, Peter B; Voolstra, Christian; Terry, Astrid Y; Miller, David J; Szmant, Alina M; Coffroth, Mary Alice; Medina, Mónica

2008-01-01

Background Scleractinian corals are the foundation of reef ecosystems in tropical marine environments. Their great success is due to interactions with endosymbiotic dinoflagellates (Symbiodinium spp.), with which they are obligately symbiotic. To develop a foundation for studying coral biology and coral symbiosis, we have constructed a set of cDNA libraries and generated and annotated ESTs from two species of corals, Acropora palmata and Montastraea faveolata. Results We generated 14,588 (Ap) and 3,854 (Mf) high quality ESTs from five life history/symbiosis stages (spawned eggs, early-stage planula larvae, late-stage planula larvae either infected with symbionts or uninfected, and adult coral). The ESTs assembled into a set of primarily stage-specific clusters, producing 4,980 (Ap), and 1,732 (Mf) unigenes. The egg stage library, relative to the other developmental stages, was enriched in genes functioning in cell division and proliferation, transcription, signal transduction, and regulation of protein function. Fifteen unigenes were identified as candidate symbiosis-related genes as they were expressed in all libraries constructed from the symbiotic stages and were absent from all of the non symbiotic stages. These include several DNA interacting proteins, and one highly expressed unigene (containing 17 cDNAs) with no significant protein-coding region. A significant number of unigenes (25) encode potential pattern recognition receptors (lectins, scavenger receptors, and others), as well as genes that may function in signaling pathways involved in innate immune responses (toll-like signaling, NFkB p105, and MAP kinases). Comparison between the A. palmata and an A. millepora EST dataset identified ferritin as a highly expressed gene in both datasets that appears to be undergoing adaptive evolution. Five unigenes appear to be restricted to the Scleractinia, as they had no homology to any sequences in the nr databases nor to the non-scleractinian cnidarians

Coral Life History and Symbiosis: functional genomic resources for two reef building Caribbean corals, Acropora palmata and Montastraea faveolata

DOE PAGES

Schwarz, Jodi A.; Brokstein, Peter B.; Voolstra, Christian R.; ...

2008-02-25

Scleractinian corals are the foundation of reef ecosystems in tropical marine environments. Their great success is due to interactions with endosymbiotic dinoflagellates (Symbiodinium spp.), with which they are obligately symbiotic. To develop a foundation for studying coral biology and coral symbiosis, we have constructed a set of cDNA libraries and generated and annotated ESTs from two species of corals, Acropora palmata and Montastraea faveolata. Here we generated 14,588 (Ap) and 3,854 (Mf) high quality ESTs from five life history/symbiosis stages (spawned eggs, early-stage planula larvae, late-stage planula larvae either infected with symbionts or uninfected, and adult coral). The ESTs assembledmore » into a set of primarily stage-specific clusters, producing 4,980 (Ap), and 1,732 (Mf) unigenes. The egg stage library, relative to the other developmental stages, was enriched in genes functioning in cell division and proliferation, transcription, signal transduction, and regulation of protein function. Fifteen unigenes were identified as candidate symbiosis-related genes as they were expressed in all libraries constructed from the symbiotic stages and were absent from all of the non symbiotic stages. These include several DNA interacting proteins, and one highly expressed unigene (containing 17 cDNAs) with no significant protein-coding region. A significant number of unigenes (25) encode potential pattern recognition receptors (lectins, scavenger receptors, and others), as well as genes that may function in signaling pathways involved in innate immune responses (toll-like signaling, NFkB p105, and MAP kinases). Comparison between the A. palmata and an A. millepora EST dataset identified ferritin as a highly expressed gene in both datasets that appears to be undergoing adaptive evolution. Five unigenes appear to be restricted to the Scleractinia, as they had no homology to any sequences in the nr databases nor to the non-scleractinian cnidarians Nematostella

Coral Life History and Symbiosis: functional genomic resources for two reef building Caribbean corals, Acropora palmata and Montastraea faveolata

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schwarz, Jodi A.; Brokstein, Peter B.; Voolstra, Christian R.

Scleractinian corals are the foundation of reef ecosystems in tropical marine environments. Their great success is due to interactions with endosymbiotic dinoflagellates (Symbiodinium spp.), with which they are obligately symbiotic. To develop a foundation for studying coral biology and coral symbiosis, we have constructed a set of cDNA libraries and generated and annotated ESTs from two species of corals, Acropora palmata and Montastraea faveolata. Here we generated 14,588 (Ap) and 3,854 (Mf) high quality ESTs from five life history/symbiosis stages (spawned eggs, early-stage planula larvae, late-stage planula larvae either infected with symbionts or uninfected, and adult coral). The ESTs assembledmore » into a set of primarily stage-specific clusters, producing 4,980 (Ap), and 1,732 (Mf) unigenes. The egg stage library, relative to the other developmental stages, was enriched in genes functioning in cell division and proliferation, transcription, signal transduction, and regulation of protein function. Fifteen unigenes were identified as candidate symbiosis-related genes as they were expressed in all libraries constructed from the symbiotic stages and were absent from all of the non symbiotic stages. These include several DNA interacting proteins, and one highly expressed unigene (containing 17 cDNAs) with no significant protein-coding region. A significant number of unigenes (25) encode potential pattern recognition receptors (lectins, scavenger receptors, and others), as well as genes that may function in signaling pathways involved in innate immune responses (toll-like signaling, NFkB p105, and MAP kinases). Comparison between the A. palmata and an A. millepora EST dataset identified ferritin as a highly expressed gene in both datasets that appears to be undergoing adaptive evolution. Five unigenes appear to be restricted to the Scleractinia, as they had no homology to any sequences in the nr databases nor to the non-scleractinian cnidarians Nematostella

The receptor kinase CERK1 has dual functions in symbiosis and immunity signalling.

PubMed

Zhang, Xiaowei; Dong, Wentao; Sun, Jongho; Feng, Feng; Deng, Yiwen; He, Zuhua; Oldroyd, Giles E D; Wang, Ertao

2015-01-01

The establishment of symbiotic interactions between mycorrhizal fungi, rhizobial bacteria and their legume hosts involves a common symbiosis signalling pathway. This signalling pathway is activated by Nod factors produced by rhizobia and these are recognised by the Nod factor receptors NFR1/LYK3 and NFR5/NFP. Mycorrhizal fungi produce lipochitooligosaccharides (LCOs) similar to Nod factors, as well as short-chain chitin oligomers (CO4/5), implying commonalities in signalling during mycorrhizal and rhizobial associations. Here we show that NFR1/LYK3, but not NFR5/NFP, is required for the establishment of the mycorrhizal interaction in legumes. NFR1/LYK3 is necessary for the recognition of mycorrhizal fungi and the activation of the symbiosis signalling pathway leading to induction of calcium oscillations and gene expression. Chitin oligosaccharides also act as microbe associated molecular patterns that promote plant immunity via similar LysM receptor-like kinases. CERK1 in rice has the highest homology to NFR1 and we show that this gene is also necessary for the establishment of the mycorrhizal interaction as well as for resistance to the rice blast fungus. Our results demonstrate that NFR1/LYK3/OsCERK1 represents a common receptor for chitooligosaccharide-based signals produced by mycorrhizal fungi, rhizobial bacteria (in legumes) and fungal pathogens. It would appear that mycorrhizal recognition has been conserved in multiple receptors across plant species, but additional diversification in certain plant species has defined other signals that this class of receptors can perceive. © 2014 The Authors The Plant Journal © 2014 John Wiley & Sons Ltd.

The mycoheterotrophic symbiosis between orchids and mycorrhizal fungi possesses major components shared with mutualistic plant-mycorrhizal symbioses.

PubMed

Miura, Chihiro; Yamaguchi, Katsushi; Miyahara, Ryohei; Yamamoto, Tatsuki; Fuji, Masako; Yagame, Takahiro; Imaizumi-Anraku, Haruko; Yamato, Masahide; Shigenobu, Shuji; Kaminaka, Hironori

2018-04-12

Achlorophylous and early developmental stages of chorolophylous orchids are highly dependent on carbon and other nutrients provided by mycorrhizal fungi, in a nutritional mode termed mycoheterotrophy. Previous findings have implied that some common properties at least partially underlie the mycorrhizal symbioses of mycoheterotrophic orchids and that of autotrophic arbuscular mycorrhizal (AM) plants; however, information about the molecular mechanisms of the relationship between orchids and their mycorrhizal fungi is limited. In this study, we characterized the molecular basis of an orchid-mycorrhizal (OM) symbiosis by analyzing the transcriptome of Bletilla striata at an early developmental stage associated with the mycorrhizal fungus Tulasnella sp. The essential components required for the establishment of mutual symbioses with AM fungi and/or rhizobia in most terrestrial plants were identified from B. striata gene set. A cross-species gene complementation analysis showed one of the component genes, calcium and calmodulin-dependent protein kinase gene CCaMK in B. striata, retains functional characteristics of that in AM plants. The expression analysis revealed the activation of homologs of AM-related genes during the OM symbiosis. Our results suggest that orchids possess, at least partly, the molecular mechanisms common to AM plants.

Breakdown of the coral-algae symbiosis: towards formalising a linkage between warm-water bleaching thresholds and the growth rate of the intracellular zooxanthellae

NASA Astrophysics Data System (ADS)

Wooldridge, S. A.

2012-07-01

Impairment of the photosynthetic machinery of the algal endosymbiont ("zooxanthellae") is the proximal trigger for the thermal breakdown of the coral-algae symbiosis ("coral bleaching"). Yet, the primary site of thermal damage is not well resolved. In this perspective essay, I consider further a recent hypothesis which proposes an energetic disruption to the carbon-concentrating mechanisms (CCMs) of the coral host, and the resultant onset of CO2-limitation within the photosynthetic "dark reactions", as a unifying cellular mechanism. The hypothesis identifies the enhanced retention of photosynthetic carbon for zooxanthellae (re)growth following an initial irradiance-driven expulsion event as the cause of the energetic disruption. If true, then it implies that the onset of the bleaching syndrome and setting of upper thermal bleaching limits are emergent attributes of the coral symbiosis that are ultimately underpinned by the characteristic growth profile of the intracellular zooxanthellae; which is known to depend not just on temperature, but also external (seawater) nutrient availability and zooxanthellae genotype. Here, I review this proposed bleaching linkage at a variety of observational scales, and find it to be parsimonious with the available evidence. This provides a new standpoint to consider the future prospects of the coral symbiosis in an era of rapid environmental change, including the now crucial importance of reef water quality in co-determining thermal bleaching resistance.

Human-Avatar Symbiosis for the Treatment of Auditory Verbal Hallucinations in Schizophrenia through Virtual/Augmented Reality and Brain-Computer Interfaces

PubMed Central

Fernández-Caballero, Antonio; Navarro, Elena; Fernández-Sotos, Patricia; González, Pascual; Ricarte, Jorge J.; Latorre, José M.; Rodriguez-Jimenez, Roberto

2017-01-01

This perspective paper faces the future of alternative treatments that take advantage of a social and cognitive approach with regards to pharmacological therapy of auditory verbal hallucinations (AVH) in patients with schizophrenia. AVH are the perception of voices in the absence of auditory stimulation and represents a severe mental health symptom. Virtual/augmented reality (VR/AR) and brain computer interfaces (BCI) are technologies that are growing more and more in different medical and psychological applications. Our position is that their combined use in computer-based therapies offers still unforeseen possibilities for the treatment of physical and mental disabilities. This is why, the paper expects that researchers and clinicians undergo a pathway toward human-avatar symbiosis for AVH by taking full advantage of new technologies. This outlook supposes to address challenging issues in the understanding of non-pharmacological treatment of schizophrenia-related disorders and the exploitation of VR/AR and BCI to achieve a real human-avatar symbiosis. PMID:29209193

Human-Avatar Symbiosis for the Treatment of Auditory Verbal Hallucinations in Schizophrenia through Virtual/Augmented Reality and Brain-Computer Interfaces.

PubMed

Fernández-Caballero, Antonio; Navarro, Elena; Fernández-Sotos, Patricia; González, Pascual; Ricarte, Jorge J; Latorre, José M; Rodriguez-Jimenez, Roberto

2017-01-01

This perspective paper faces the future of alternative treatments that take advantage of a social and cognitive approach with regards to pharmacological therapy of auditory verbal hallucinations (AVH) in patients with schizophrenia. AVH are the perception of voices in the absence of auditory stimulation and represents a severe mental health symptom. Virtual/augmented reality (VR/AR) and brain computer interfaces (BCI) are technologies that are growing more and more in different medical and psychological applications. Our position is that their combined use in computer-based therapies offers still unforeseen possibilities for the treatment of physical and mental disabilities. This is why, the paper expects that researchers and clinicians undergo a pathway toward human-avatar symbiosis for AVH by taking full advantage of new technologies. This outlook supposes to address challenging issues in the understanding of non-pharmacological treatment of schizophrenia-related disorders and the exploitation of VR/AR and BCI to achieve a real human-avatar symbiosis.

First Detailed Record of Symbiosis Between a Sea Anemone and Homoscleromorph Sponge, With a Description of Tempuractis rinkai gen. et sp. nov. (Cnidaria: Anthozoa: Actiniaria: Edwardsiidae).

PubMed

Izumi, Takato; Ise, Yuji; Yanagi, Kensuke; Shibata, Daisuke; Ueshima, Rei

2018-04-01

A new species in a new genus of sea anemone, Tempuractis rinkai gen. et sp. nov., was discovered at several localities along the temperate rocky shores of Japan. The new species is approximately 4 mm in length and has been assigned to family Edwardsiidae, because it has eight macrocnemes, lacks sphincter and basal muscles, and possesses rounded aboral end. The sea anemone, however, also has a peculiar body shape unlike that of any other known taxa. This new species resembles some genera, especially Drillactis and Nematostella, in smooth column surface without nemathybomes or tenaculi, but is distinguishable from them by several morphological features: the presence of holotrichs and absence of nematosomes. Furthermore, this edwardsiid species exhibits a peculiar symbiotic ecology with sponges. Therefore, a new genus, Tempuractis, is proposed for this species. In the field, T. rinkai sp. nov. was always found living inside homosclerophorid sponge of the genus Oscarella, which suggests a possible obligate symbiosis between Porifera and Actiniaria. The benefit of this symbiosis is discussed on the basis of observations of live specimens, both in the aquarium and field. This is the first report of symbiosis between a sea anemone and a homoscleromorph sponge.

Development of Regulatory Processes in the Symbiosis Between the Sea Anemone Aiptasia pallida and its Dinoflagellate Symbionts

DTIC Science & Technology

1994-09-01

affected both dinoflagellates ( zooxanthellae ) and their hosts. Studies included the infection of algae-free hosts, responses to "host factors...34, metabolism of 15 N-ammonium and other aspects of how nitrogen was utilized by the symbiotic systems. Zooxanthellae of A. pallida showed distinct reposes to...S’ Symbiosis, zooxanthellae , dinoflagellates, sea anemones, IC i corals Unclassified Unclassified jUnclassified UL TABLE OF CONTENTS Page # Summary

Book review of Insect Symbiosis. Volume 2. Bourtzis, K.A. and Miller, T.A. editros. 2006 CRC Press, Taylor and Francis Group, Boca Raton, FL, 276 pp. ISBN 0-8493-1286-8

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hoy, M.A.

There are several definitions of symbiosis, but in this book it involves an association where one organism (the symbiont) lives within or on the body of another organism (the host), regardless of the actual effect on the host. Some symbioses are mutualistic, some parasitic, and some involve commensalism, in which one partner derives some benefit without either harming or benefiting the other. This is the second volume in this exciting and rapidly advancing topic by these editors. The first volume was published in 2003 and during the intervening three years additional data have been produced that make this book amore » useful addition to your library. The first book provided chapters that provided an overview of insect symbiosis, discussions of the primary aphid symbiont Buchnera and other aphid symbionts, symbiosis in tsetse, symbionts in the weevil Sitophilus , the possible use of paratransgenic symbionts of Rhodnius prolixis to prevent disease transmission, bark beetle and fungal symbiosis, symbionts of tephritid fruit flies, symbionts affecting termite behavior, an overview of microsporidia as symbionts (parasites?) of insects, an overview of a newly discovered bacterium that causes sex-ratio distortion in insects and mites (from the Bacteroides group), symbionts that selectively kill male insects, and several chapters on the ubiquitous endosymbiont Wolbachia.« less

Reciprocal genomic evolution in the ant–fungus agricultural symbiosis

PubMed Central

Nygaard, Sanne; Hu, Haofu; Li, Cai; Schiøtt, Morten; Chen, Zhensheng; Yang, Zhikai; Xie, Qiaolin; Ma, Chunyu; Deng, Yuan; Dikow, Rebecca B.; Rabeling, Christian; Nash, David R.; Wcislo, William T.; Brady, Seán G.; Schultz, Ted R.; Zhang, Guojie; Boomsma, Jacobus J.

2016-01-01

The attine ant–fungus agricultural symbiosis evolved over tens of millions of years, producing complex societies with industrial-scale farming analogous to that of humans. Here we document reciprocal shifts in the genomes and transcriptomes of seven fungus-farming ant species and their fungal cultivars. We show that ant subsistence farming probably originated in the early Tertiary (55–60 MYA), followed by further transitions to the farming of fully domesticated cultivars and leaf-cutting, both arising earlier than previously estimated. Evolutionary modifications in the ants include unprecedented rates of genome-wide structural rearrangement, early loss of arginine biosynthesis and positive selection on chitinase pathways. Modifications of fungal cultivars include loss of a key ligninase domain, changes in chitin synthesis and a reduction in carbohydrate-degrading enzymes as the ants gradually transitioned to functional herbivory. In contrast to human farming, increasing dependence on a single cultivar lineage appears to have been essential to the origin of industrial-scale ant agriculture. PMID:27436133

The genome of the intracellular bacterium of the coastal bivalve, Solemya velum: a blueprint for thriving in and out of symbiosis.

PubMed

Dmytrenko, Oleg; Russell, Shelbi L; Loo, Wesley T; Fontanez, Kristina M; Liao, Li; Roeselers, Guus; Sharma, Raghav; Stewart, Frank J; Newton, Irene L G; Woyke, Tanja; Wu, Dongying; Lang, Jenna Morgan; Eisen, Jonathan A; Cavanaugh, Colleen M

2014-10-23

Symbioses between chemoautotrophic bacteria and marine invertebrates are rare examples of living systems that are virtually independent of photosynthetic primary production. These associations have evolved multiple times in marine habitats, such as deep-sea hydrothermal vents and reducing sediments, characterized by steep gradients of oxygen and reduced chemicals. Due to difficulties associated with maintaining these symbioses in the laboratory and culturing the symbiotic bacteria, studies of chemosynthetic symbioses rely heavily on culture independent methods. The symbiosis between the coastal bivalve, Solemya velum, and its intracellular symbiont is a model for chemosynthetic symbioses given its accessibility in intertidal environments and the ability to maintain it under laboratory conditions. To better understand this symbiosis, the genome of the S. velum endosymbiont was sequenced. Relative to the genomes of obligate symbiotic bacteria, which commonly undergo erosion and reduction, the S. velum symbiont genome was large (2.7 Mb), GC-rich (51%), and contained a large number (78) of mobile genetic elements. Comparative genomics identified sets of genes specific to the chemosynthetic lifestyle and necessary to sustain the symbiosis. In addition, a number of inferred metabolic pathways and cellular processes, including heterotrophy, branched electron transport, and motility, suggested that besides the ability to function as an endosymbiont, the bacterium may have the capacity to live outside the host. The physiological dexterity indicated by the genome substantially improves our understanding of the genetic and metabolic capabilities of the S. velum symbiont and the breadth of niches the partners may inhabit during their lifecycle.

The genome of the intracellular bacterium of the coastal bivalve, Solemya velum: a blueprint for thriving in and out of symbiosis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dmytrenko, Oleg; Russell, Shelbi L.; Loo, Wesley T.

Background: Symbioses between chemoautotrophic bacteria and marine invertebrates are rare examples of living systems that are virtually independent of photosynthetic primary production. These associations have evolved multiple times in marine habitats, such as deep-sea hydrothermal vents and reducing sediments, characterized by steep gradients of oxygen and reduced chemicals. Due to difficulties associated with maintaining these symbioses in the laboratory and culturing the symbiotic bacteria, studies of chemosynthetic symbioses rely heavily on culture independent methods. The symbiosis between the coastal bivalve, Solemya velum, and its intracellular symbiont is a model for chemosynthetic symbioses given its accessibility in intertidal environments and themore » ability to maintain it under laboratory conditions. To better understand this symbiosis, the genome of the S. velum endosymbiont was sequenced. Results: Relative to the genomes of obligate symbiotic bacteria, which commonly undergo erosion and reduction, the S. velum symbiont genome was large (2.86 Mb), GC-rich (50.4percent), and contained a large number (78) of mobile genetic elements. Comparative genomics identified sets of genes specific to the chemosynthetic lifestyle and necessary to sustain the symbiosis. In addition, a number of inferred metabolic pathways and cellular processes, including heterotrophy, branched electron transport, and motility, suggested that besides the ability to function as an endosymbiont, the bacterium may have the capacity to live outside the host. Conclusions: The physiological dexterity indicated by the genome substantially improves our understanding of the genetic and metabolic capabilities of the S. velum symbiont and the breadth of niches the partners may inhabit during their lifecycle« less

The genome of the intracellular bacterium of the coastal bivalve, Solemya velum: a blueprint for thriving in and out of symbiosis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dmytrenko, Oleg; Russell, Shelbi L.; Loo, Wesley T.

Symbioses between chemoautotrophic bacteria and marine invertebrates are rare examples of living systems that are virtually independent of photosynthetic primary production. These associations have evolved multiple times in marine habitats, such as deep-sea hydrothermal vents and reducing sediments, characterized by steep gradients of oxygen and reduced chemicals. Due to difficulties associated with maintaining these symbioses in the laboratory and culturing the symbiotic bacteria, studies of chemosynthetic symbioses rely heavily on culture independent methods. The symbiosis between the coastal bivalve, Solemya velum, and its intracellular symbiont is a model for chemosynthetic symbioses given its accessibility in intertidal environments and the abilitymore » to maintain it under laboratory conditions. Here, to better understand this symbiosis, the genome of the S. velum endosymbiont was sequenced. Relative to the genomes of obligate symbiotic bacteria, which commonly undergo erosion and reduction, the S. velum symbiont genome was large (2.7 Mb), GC-rich (51%), and contained a large number (78) of mobile genetic elements. Comparative genomics identified sets of genes specific to the chemosynthetic lifestyle and necessary to sustain the symbiosis. In addition, a number of inferred metabolic pathways and cellular processes, including heterotrophy, branched electron transport, and motility, suggested that besides the ability to function as an endosymbiont, the bacterium may have the capacity to live outside the host. In conclusion, the physiological dexterity indicated by the genome substantially improves our understanding of the genetic and metabolic capabilities of the S. velum symbiont and the breadth of niches the partners may inhabit during their lifecycle.« less

The genome of the intracellular bacterium of the coastal bivalve, Solemya velum: a blueprint for thriving in and out of symbiosis

DOE PAGES

Dmytrenko, Oleg; Russell, Shelbi L.; Loo, Wesley T.; ...

2014-10-23

Symbioses between chemoautotrophic bacteria and marine invertebrates are rare examples of living systems that are virtually independent of photosynthetic primary production. These associations have evolved multiple times in marine habitats, such as deep-sea hydrothermal vents and reducing sediments, characterized by steep gradients of oxygen and reduced chemicals. Due to difficulties associated with maintaining these symbioses in the laboratory and culturing the symbiotic bacteria, studies of chemosynthetic symbioses rely heavily on culture independent methods. The symbiosis between the coastal bivalve, Solemya velum, and its intracellular symbiont is a model for chemosynthetic symbioses given its accessibility in intertidal environments and the abilitymore » to maintain it under laboratory conditions. Here, to better understand this symbiosis, the genome of the S. velum endosymbiont was sequenced. Relative to the genomes of obligate symbiotic bacteria, which commonly undergo erosion and reduction, the S. velum symbiont genome was large (2.7 Mb), GC-rich (51%), and contained a large number (78) of mobile genetic elements. Comparative genomics identified sets of genes specific to the chemosynthetic lifestyle and necessary to sustain the symbiosis. In addition, a number of inferred metabolic pathways and cellular processes, including heterotrophy, branched electron transport, and motility, suggested that besides the ability to function as an endosymbiont, the bacterium may have the capacity to live outside the host. In conclusion, the physiological dexterity indicated by the genome substantially improves our understanding of the genetic and metabolic capabilities of the S. velum symbiont and the breadth of niches the partners may inhabit during their lifecycle.« less

Regulation of cation transporter genes by the arbuscular mycorrhizal symbiosis in rice plants subjected to salinity suggests improved salt tolerance due to reduced Na(+) root-to-shoot distribution.

PubMed

Porcel, Rosa; Aroca, Ricardo; Azcon, Rosario; Ruiz-Lozano, Juan Manuel

2016-10-01

Rice is a salt-sensitive crop whose productivity is strongly reduced by salinity around the world. Plants growing in saline soils are subjected to the toxicity of specific ions such as sodium, which damage cell organelles and disrupt metabolism. Plants have evolved biochemical and molecular mechanisms to cope with the negative effects of salinity. These include the regulation of genes with a role in the uptake, transport or compartmentation of Na(+) and/or K(+). Studies have shown that the arbuscular mycorrhizal (AM) symbiosis alleviates salt stress in several host plant species. However, despite the abundant literature showing mitigation of ionic imbalance by the AM symbiosis, the molecular mechanisms involved are barely explored. The objective of this study was to elucidate the effects of the AM symbiosis on the expression of several well-known rice transporters involved in Na(+)/K(+) homeostasis and measure Na(+) and K(+) contents and their ratios in different plant tissues. Results showed that OsNHX3, OsSOS1, OsHKT2;1 and OsHKT1;5 genes were considerably upregulated in AM plants under saline conditions as compared to non-AM plants. Results suggest that the AM symbiosis favours Na(+) extrusion from the cytoplasm, its sequestration into the vacuole, the unloading of Na(+) from the xylem and its recirculation from photosynthetic organs to roots. As a result, there is a decrease of Na(+) root-to-shoot distribution and an increase of Na(+) accumulation in rice roots which seems to enhance the plant tolerance to salinity and allows AM rice plants to maintain their growing processes under salt conditions.

An improved method for Agrobacterium rhizogenes-mediated transformation of tomato suitable for the study of arbuscular mycorrhizal symbiosis.

PubMed

Ho-Plágaro, Tania; Huertas, Raúl; Tamayo-Navarrete, María I; Ocampo, Juan A; García-Garrido, José M

2018-01-01

Solanum lycopersicum , an economically important crop grown worldwide, has been used as a model for the study of arbuscular mycorrhizal (AM) symbiosis in non-legume plants for several years and several cDNA array hybridization studies have revealed specific transcriptomic profiles of mycorrhizal tomato roots. However, a method to easily screen candidate genes which could play an important role during tomato mycorrhization is required. We have developed an optimized procedure for composite tomato plant obtaining achieved through Agrobacterium rhizogenes -mediated transformation. This protocol involves the unusual in vitro culture of composite plants between two filter papers placed on the culture media. In addition, we show that DsRed is an appropriate molecular marker for the precise selection of cotransformed tomato hairy roots . S. lycopersicum composite plant hairy roots appear to be colonized by the AM fungus Rhizophagus irregularis in a manner similar to that of normal roots, and a modified construct useful for localizing the expression of promoters putatively associated with mycorrhization was developed and tested. In this study, we present an easy, fast and low-cost procedure to study AM symbiosis in tomato roots.

Competition between Vibrio fischeri strains during initiation and maintenance of a light organ symbiosis.

PubMed

Lee, K H; Ruby, E G

1994-04-01

Colonization of the light-emitting organ of the Hawaiian squid Euprymna scolopes is initiated when the nascent organ of a newly hatched squid becomes inoculated with Vibrio fischeri cells present in the ambient seawater. Although they are induced for luminescence in the light organ, these symbiotic strains are characteristically non-visibly luminous (NVL) when grown in laboratory culture. The more typical visibly luminous (VL) type of V. fischeri co-occurs in Hawaiian seawater with these NVL strains; thus, two phenotypically distinct groups of this species potentially have access to the symbiotic niche, yet only the NVL ones are found there. In laboratory inoculation experiments, VL strains, when presented in pure culture, showed the same capability for colonizing the light organ as NVL strains. However, in experiments with mixed cultures composed of both VL and NVL strains, the VL ones were unable to compete with the NVL ones and did not persist within the light organ as the symbiosis became established. In addition, NVL strains entered light organs that had already been colonized by VL strains and displaced them. The mechanism underlying the symbiotic competitiveness exhibited by NVL strains remains unknown; however, it does not appear to be due to a higher potential for siderophore activity. While a difference in luminescence phenotype between VL and NVL strains in culture is not likely to be significant in the symbiosis, it has helped identify two distinct groups of V. fischeri that express different colonization capabilities in the squid light organ. This competitive difference provides a useful indication of important traits in light organ colonization.

Competition between Vibrio fischeri strains during initiation and maintenance of a light organ symbiosis.

PubMed Central

Lee, K H; Ruby, E G

1994-01-01

Colonization of the light-emitting organ of the Hawaiian squid Euprymna scolopes is initiated when the nascent organ of a newly hatched squid becomes inoculated with Vibrio fischeri cells present in the ambient seawater. Although they are induced for luminescence in the light organ, these symbiotic strains are characteristically non-visibly luminous (NVL) when grown in laboratory culture. The more typical visibly luminous (VL) type of V. fischeri co-occurs in Hawaiian seawater with these NVL strains; thus, two phenotypically distinct groups of this species potentially have access to the symbiotic niche, yet only the NVL ones are found there. In laboratory inoculation experiments, VL strains, when presented in pure culture, showed the same capability for colonizing the light organ as NVL strains. However, in experiments with mixed cultures composed of both VL and NVL strains, the VL ones were unable to compete with the NVL ones and did not persist within the light organ as the symbiosis became established. In addition, NVL strains entered light organs that had already been colonized by VL strains and displaced them. The mechanism underlying the symbiotic competitiveness exhibited by NVL strains remains unknown; however, it does not appear to be due to a higher potential for siderophore activity. While a difference in luminescence phenotype between VL and NVL strains in culture is not likely to be significant in the symbiosis, it has helped identify two distinct groups of V. fischeri that express different colonization capabilities in the squid light organ. This competitive difference provides a useful indication of important traits in light organ colonization. PMID:8144466

Does plant immunity play a critical role during initiation of the legume-rhizobium symbiosis?

PubMed

Tóth, Katalin; Stacey, Gary

2015-01-01

Plants are exposed to many different microbes in their habitats. These microbes may be benign or pathogenic, but in some cases they are beneficial for the host. The rhizosphere provides an especially rich palette for colonization by beneficial (associative and symbiotic) microorganisms, which raises the question as to how roots can distinguish such 'friends' from possible 'foes' (i.e., pathogens). Plants possess an innate immune system that can recognize pathogens, through an arsenal of protein receptors, including receptor-like kinases (RLKs) and receptor-like proteins (RLPs) located at the plasma membrane. In addition, the plant host has intracellular receptors (so called NBS-LRR proteins or R proteins) that directly or indirectly recognize molecules released by microbes into the plant cell. A successful cooperation between legume plants and rhizobia leads to beneficial symbiotic interaction. The key rhizobial, symbiotic signaling molecules [lipo-chitooligosaccharide Nod factors (NF)] are perceived by the host legume plant using lysin motif-domain containing RLKs. Perception of the symbiotic NFs trigger signaling cascades leading to bacterial infection and accommodation of the symbiont in a newly formed root organ, the nodule, resulting in a nitrogen-fixing root nodule symbiosis. The net result of this symbiosis is the intracellular colonization of the plant with thousands of bacteria; a process that seems to occur in spite of the immune ability of plants to prevent pathogen infection. In this review, we discuss the potential of the invading rhizobial symbiont to actively avoid this innate immune response, as well as specific examples of where the plant immune response may modulate rhizobial infection and host range.

Rhizobiales as functional and endosymbiontic members in the lichen symbiosis of Lobaria pulmonaria L.

PubMed Central

Erlacher, Armin; Cernava, Tomislav; Cardinale, Massimiliano; Soh, Jung; Sensen, Christoph W.; Grube, Martin; Berg, Gabriele

2015-01-01

Rhizobiales (Alphaproteobacteria) are well-known beneficial partners in plant-microbe interactions. Less is known about the occurrence and function of Rhizobiales in the lichen symbiosis, although it has previously been shown that Alphaproteobacteria are the dominating group in growing lichen thalli. We have analyzed the taxonomic structure and assigned functions to Rhizobiales within a metagenomic dataset of the lung lichen Lobaria pulmonaria L. One third (32.2%) of the overall bacteria belong to the Rhizobiales, in particular to the families Methylobacteriaceae, Bradyrhizobiaceae, and Rhizobiaceae. About 20% of our metagenomic assignments could not be placed in any of the Rhizobiales lineages, which indicates a yet undescribed bacterial diversity. SEED-based functional analysis focused on Rhizobiales and revealed functions supporting the symbiosis, including auxin and vitamin production, nitrogen fixation and stress protection. We also have used a specifically developed probe to localize Rhizobiales by confocal laser scanning microscopy after fluorescence in situ hybridization (FISH-CLSM). Bacteria preferentially colonized fungal surfaces, but there is clear evidence that members of the Rhizobiales are able to intrude at varying depths into the interhyphal gelatinous matrix of the upper lichen cortical layer and that at least occasionally some bacteria also are capable to colonize the interior of the fungal hyphae. Interestingly, the gradual development of an endosymbiotic bacterial life was found for lichen- as well as for fungal- and plant-associated bacteria. The new tools to study Rhizobiales, FISH microscopy and comparative metagenomics, suggest a similar beneficial role for lichens than for plants and will help to better understand the Rhizobiales-host interaction and their biotechnological potential. PMID:25713563

Fungal symbiosis and precipitation alter traits and dune building by the ecosystem engineer, Ammophila breviligulata.

PubMed

Emery, Sarah M; Bell-Dereske, Lukas; Rudgers, Jennifer A

2015-04-01

Ecosystem engineer species influence their community and ecosystem by creating or altering the physical structure of habitats. The function of ecosystem engineers is variable and can depend on both abiotic and biotic factors. Here we make use of a primary successional system to evaluate the direct and interactive effects of climate change (precipitation) and fungal endophyte symbiosis on population traits and ecosystem function of the ecosystem engineering grass species, Ammophila breviligulata. We manipulated endophyte presence in A. breviligulata in combination with rain-out shelters and rainfall additions in a factorial field experiment established in 2010 on Lake Michigan sand dunes. We monitored plant traits, survival, growth, and sexual reproduction of A. breviligulata from 2010-2013, and quantified ecosystem engineering as the sand accumulation rate. Presence of the endophyte in A. breviligulata increased vegetative growth by up to 19%, and reduced sexual reproduction by up to 46% across all precipitation treatments. Precipitation was a less significant factor than endophyte colonization for A. breviligulata growth. Reduced precipitation increased average leaf number per tiller but had no other effects on plant traits. Changes in A. breviligulata traits corresponded to increases in sand accumulation in plots with the endophyte as well as in plots with reduced precipitation. Sand accumulation is a key ecosystem function in these primary successional habitats, and so microbial symbiosis in this ecosystem engineer could lead to direct effects on the value of these dune habitats for humans.

Gr and hp-1 tomato mutants unveil unprecedented interactions between arbuscular mycorrhizal symbiosis and fruit ripening.

PubMed

Chialva, Matteo; Zouari, Inès; Salvioli, Alessandra; Novero, Mara; Vrebalov, Julia; Giovannoni, James J; Bonfante, Paola

2016-07-01

Systemic responses to an arbuscular mycorrhizal fungus reveal opposite phenological patterns in two tomato ripening mutants depending whether ethylene or light reception is involved. The availability of tomato ripening mutants has revealed many aspects of the genetics behind fleshy fruit ripening, plant hormones and light signal reception. Since previous analyses revealed that arbuscular mycorrhizal symbiosis influences tomato berry ripening, we wanted to test the hypothesis that an interplay might occur between root symbiosis and fruit ripening. With this aim, we screened seven tomato mutants affected in the ripening process for their responsiveness to the arbuscular mycorrhizal fungus Funneliformis mosseae. Following their phenological responses we selected two mutants for a deeper analysis: Green ripe (Gr), deficient in fruit ethylene perception and high-pigment-1 (hp-1), displaying enhanced light signal perception throughout the plant. We investigated the putative interactions between ripening processes, mycorrhizal establishment and systemic effects using biochemical and gene expression tools. Our experiments showed that both mutants, notwithstanding a normal mycorrhizal phenotype at root level, exhibit altered arbuscule functionality. Furthermore, in contrast to wild type, mycorrhization did not lead to a higher phosphate concentration in berries of both mutants. These results suggest that the mutations considered interfere with arbuscular mycorrhiza inducing systemic changes in plant phenology and fruits metabolism. We hypothesize a cross talk mechanism between AM and ripening processes that involves genes related to ethylene and light signaling.

Discovery of chemoautotrophic symbiosis in the giant shipworm Kuphus polythalamia (Bivalvia: Teredinidae) extends wooden-steps theory.

PubMed

Distel, Daniel L; Altamia, Marvin A; Lin, Zhenjian; Shipway, J Reuben; Han, Andrew; Forteza, Imelda; Antemano, Rowena; Limbaco, Ma Gwen J Peñaflor; Tebo, Alison G; Dechavez, Rande; Albano, Julie; Rosenberg, Gary; Concepcion, Gisela P; Schmidt, Eric W; Haygood, Margo G

2017-05-02

The "wooden-steps" hypothesis [Distel DL, et al. (2000) Nature 403:725-726] proposed that large chemosynthetic mussels found at deep-sea hydrothermal vents descend from much smaller species associated with sunken wood and other organic deposits, and that the endosymbionts of these progenitors made use of hydrogen sulfide from biogenic sources (e.g., decaying wood) rather than from vent fluids. Here, we show that wood has served not only as a stepping stone between habitats but also as a bridge between heterotrophic and chemoautotrophic symbiosis for the giant mud-boring bivalve Kuphus polythalamia This rare and enigmatic species, which achieves the greatest length of any extant bivalve, is the only described member of the wood-boring bivalve family Teredinidae (shipworms) that burrows in marine sediments rather than wood. We show that K. polythalamia harbors sulfur-oxidizing chemoautotrophic (thioautotrophic) bacteria instead of the cellulolytic symbionts that allow other shipworm species to consume wood as food. The characteristics of its symbionts, its phylogenetic position within Teredinidae, the reduction of its digestive system by comparison with other family members, and the loss of morphological features associated with wood digestion indicate that K. polythalamia is a chemoautotrophic bivalve descended from wood-feeding (xylotrophic) ancestors. This is an example in which a chemoautotrophic endosymbiosis arose by displacement of an ancestral heterotrophic symbiosis and a report of pure culture of a thioautotrophic endosymbiont.

Arbuscular Mycorrhizal Symbiosis Alleviates Salt Stress in Black Locust through Improved Photosynthesis, Water Status, and K+/Na+ Homeostasis

PubMed Central

Chen, Jie; Zhang, Haoqiang; Zhang, Xinlu; Tang, Ming

2017-01-01

Soil salinization and the associated land degradation are major and growing ecological problems. Excess salt in soil impedes plant photosynthetic processes and root uptake of water and nutrients such as K+. Arbuscular mycorrhizal (AM) fungi can mitigate salt stress in host plants. Although, numerous studies demonstrate that photosynthesis and water status are improved by mycorrhizae, the molecular mechanisms involved have received little research attention. In the present study, we analyzed the effects of AM symbiosis and salt stress on photosynthesis, water status, concentrations of Na+ and K+, and the expression of several genes associated with photosynthesis (RppsbA, RppsbD, RprbcL, and RprbcS) and genes coding for aquaporins or membrane transport proteins involved in K+ and/or Na+ uptake, translocation, or compartmentalization homeostasis (RpSOS1, RpHKT1, RpNHX1, and RpSKOR) in black locust. The results showed that salinity reduced the net photosynthetic rate, stomatal conductance, and relative water content in both non-mycorrhizal (NM) and AM plants; the reductions of these three parameters were less in AM plants compared with NM plants. Under saline conditions, AM fungi significantly improved the net photosynthetic rate, quantum efficiency of photosystem II photochemistry, and K+ content in plants, but evidently reduced the Na+ content. AM plants also displayed a significant increase in the relative water content and an evident decrease in the shoot/root ratio of Na+ in the presence of 200 mM NaCl compared with NM plants. Additionally, mycorrhizal colonization upregulated the expression of three chloroplast genes (RppsbA, RppsbD, and RprbcL) in leaves, and three genes (RpSOS1, RpHKT1, and RpSKOR) encoding membrane transport proteins involved in K+/Na+ homeostasis in roots. Expression of several aquaporin genes was regulated by AM symbiosis in both leaves and roots depending on soil salinity. This study suggests that the beneficial effects of AM symbiosis on

Symbiosis Island Shuffling with Abundant Insertion Sequences in the Genomes of Extra-Slow-Growing Strains of Soybean Bradyrhizobia

PubMed Central

Iida, Takayuki; Itakura, Manabu; Anda, Mizue; Sugawara, Masayuki; Isawa, Tsuyoshi; Okubo, Takashi; Sato, Shusei; Chiba-Kakizaki, Kaori

2015-01-01

Extra-slow-growing bradyrhizobia from root nodules of field-grown soybeans harbor abundant insertion sequences (ISs) and are termed highly reiterated sequence-possessing (HRS) strains. We analyzed the genome organization of HRS strains with the focus on IS distribution and symbiosis island structure. Using pulsed-field gel electrophoresis, we consistently detected several plasmids (0.07 to 0.4 Mb) in the HRS strains (NK5, NK6, USDA135, 2281, USDA123, and T2), whereas no plasmids were detected in the non-HRS strain USDA110. The chromosomes of the six HRS strains (9.7 to 10.7 Mb) were larger than that of USDA110 (9.1 Mb). Using MiSeq sequences of 6 HRS and 17 non-HRS strains mapped to the USDA110 genome, we found that the copy numbers of ISRj1, ISRj2, ISFK1, IS1632, ISB27, ISBj8, and IS1631 were markedly higher in HRS strains. Whole-genome sequencing showed that the HRS strain NK6 had four small plasmids (136 to 212 kb) and a large chromosome (9,780 kb). Strong colinearity was found between 7.4-Mb core regions of the NK6 and USDA110 chromosomes. USDA110 symbiosis islands corresponded mainly to five small regions (S1 to S5) within two variable regions, V1 (0.8 Mb) and V2 (1.6 Mb), of the NK6 chromosome. The USDA110 nif gene cluster (nifDKENXSBZHQW-fixBCX) was split into two regions, S2 and S3, where ISRj1-mediated rearrangement occurred between nifS and nifB. ISs were also scattered in NK6 core regions, and ISRj1 insertion often disrupted some genes important for survival and environmental responses. These results suggest that HRS strains of soybean bradyrhizobia were subjected to IS-mediated symbiosis island shuffling and core genome degradation. PMID:25862225

Arbuscular Mycorrhizal Symbiosis Alleviates Salt Stress in Black Locust through Improved Photosynthesis, Water Status, and K+/Na+ Homeostasis.

PubMed

Chen, Jie; Zhang, Haoqiang; Zhang, Xinlu; Tang, Ming

2017-01-01

Soil salinization and the associated land degradation are major and growing ecological problems. Excess salt in soil impedes plant photosynthetic processes and root uptake of water and nutrients such as K + . Arbuscular mycorrhizal (AM) fungi can mitigate salt stress in host plants. Although, numerous studies demonstrate that photosynthesis and water status are improved by mycorrhizae, the molecular mechanisms involved have received little research attention. In the present study, we analyzed the effects of AM symbiosis and salt stress on photosynthesis, water status, concentrations of Na + and K + , and the expression of several genes associated with photosynthesis ( RppsbA, RppsbD, RprbcL , and RprbcS ) and genes coding for aquaporins or membrane transport proteins involved in K + and/or Na + uptake, translocation, or compartmentalization homeostasis ( RpSOS1, RpHKT1, RpNHX1 , and RpSKOR ) in black locust. The results showed that salinity reduced the net photosynthetic rate, stomatal conductance, and relative water content in both non-mycorrhizal (NM) and AM plants; the reductions of these three parameters were less in AM plants compared with NM plants. Under saline conditions, AM fungi significantly improved the net photosynthetic rate, quantum efficiency of photosystem II photochemistry, and K + content in plants, but evidently reduced the Na + content. AM plants also displayed a significant increase in the relative water content and an evident decrease in the shoot/root ratio of Na + in the presence of 200 mM NaCl compared with NM plants. Additionally, mycorrhizal colonization upregulated the expression of three chloroplast genes ( RppsbA, RppsbD , and RprbcL ) in leaves, and three genes ( RpSOS1, RpHKT1 , and RpSKOR ) encoding membrane transport proteins involved in K + /Na + homeostasis in roots. Expression of several aquaporin genes was regulated by AM symbiosis in both leaves and roots depending on soil salinity. This study suggests that the beneficial

Mycorrhizal symbiosis increases growth, reproduction and recruitment of Abutilon theophrasti Medic. in the field.

PubMed

Stanley, Margot R; Koide, Roger T; Shumway, Durland L

1993-05-01

We examined in the field the effect of the vesicular-arbuscular (VA) mycorhizal symbiosis on the reproductive success of Abutilon theophrasti Medic., an early successional annual member of the Malvaceae. Mycorrhizal infection greatly enhanced vegetative growth, and flower, fruit and seed production, resulting in significantly greater recruitment the following year. In addition, the seeds produced by mycorrhizal plants were significantly larger and contained significantly more phosphorus than seeds from non-mycorrhizal plants, an effect which may improve offspring vigor. Infection by mycorrhizal fungi may thus contribute to the overall fitness of a host plant and strongly influence long-term plant population dynamics.

Response pattern of amino compounds in phloem and xylem of trees to soil drought depends on drought intensity and root symbiosis.

PubMed

Liu, X-P; Gong, C-M; Fan, Y-Y; Eiblmeier, M; Zhao, Z; Han, G; Rennenberg, H

2013-01-01

This study aimed to identify drought-mediated differences in amino nitrogen (N) composition and content of xylem and phloem in trees having different symbiotic N(2)-fixing bacteria. Under controlled water availability, 1-year-old seedlings of Robinia pseudoacacia (nodules with Rhizobium), Hippophae rhamnoides (symbiosis with Frankia) and Buddleja alternifolia (no such root symbiosis) were exposed to control, medium drought and severe drought, corresponding soil water content of 70-75%, 45-50% and 30-35% of field capacity, respectively. Composition and content of amino compounds in xylem sap and phloem exudates were analysed as a measure of N nutrition. Drought strongly reduced biomass accumulation in all species, but amino N content in xylem and phloem remained unaffected only in R. pseudoacacia. In H. rhamnoides and B. alternifolia, amino N in phloem remained constant, but increased in xylem of both species in response to drought. There were differences in composition of amino compounds in xylem and phloem of the three species in response to drought. Proline concentrations in long-distance transport pathways of all three species were very low, below the limit of detection in phloem of H. rhamnoides and in phloem and xylem of B. alternifolia. Apparently, drought-mediated changes in N composition were much more connected with species-specific changes in C:N ratios. Irrespective of soil water content, the two species with root symbioses did not show similar features for the different types of symbiosis, neither in N composition nor in N content. There was no immediate correlation between symbiotic N fixation and drought-mediated changes in amino N in the transport pathways. © 2012 German Botanical Society and The Royal Botanical Society of the Netherlands.

Engineering Plant-Microbe Symbiosis for Rhizoremediation of Heavy Metals

PubMed Central

Wu, Cindy H.; Wood, Thomas K.; Mulchandani, Ashok; Chen, Wilfred

2006-01-01

The use of plants for rehabilitation of heavy-metal-contaminated environments is an emerging area of interest because it provides an ecologically sound and safe method for restoration and remediation. Although a number of plant species are capable of hyperaccumulation of heavy metals, the technology is not applicable for remediating sites with multiple contaminants. A clever solution is to combine the advantages of microbe-plant symbiosis within the plant rhizosphere into an effective cleanup technology. We demonstrated that expression of a metal-binding peptide (EC20) in a rhizobacterium, Pseudomonas putida 06909, not only improved cadmium binding but also alleviated the cellular toxicity of cadmium. More importantly, inoculation of sunflower roots with the engineered rhizobacterium resulted in a marked decrease in cadmium phytotoxicity and a 40% increase in cadmium accumulation in the plant root. Owing to the significantly improved growth characteristics of both the rhizobacterium and plant, the use of EC20-expressing P. putida endowed with organic-degrading capabilities may be a promising strategy to remediate mixed organic-metal-contaminated sites. PMID:16461658

Man-Robot Symbiosis: A Framework For Cooperative Intelligence And Control

NASA Astrophysics Data System (ADS)

Parker, Lynne E.; Pin, Francois G.

1988-10-01

The man-robot symbiosis concept has the fundamental objective of bridging the gap between fully human-controlled and fully autonomous systems to achieve true man-robot cooperative control and intelligence. Such a system would allow improved speed, accuracy, and efficiency of task execution, while retaining the man in the loop for innovative reasoning and decision-making. The symbiont would have capabilities for supervised and unsupervised learning, allowing an increase of expertise in a wide task domain. This paper describes a robotic system architecture facilitating the symbiotic integration of teleoperative and automated modes of task execution. The architecture reflects a unique blend of many disciplines of artificial intelligence into a working system, including job or mission planning, dynamic task allocation, man-robot communication, automated monitoring, and machine learning. These disciplines are embodied in five major components of the symbiotic framework: the Job Planner, the Dynamic Task Allocator, the Presenter/Interpreter, the Automated Monitor, and the Learning System.

Aspects of narcissism and symbiosis, or, essential neurosis of twins.

PubMed

Kahn, Charlotte

2012-06-01

Following a brief introduction I address the relationships of twins from five different perspectives: the Intimate Connection, the Mirror Image and Complementarity, Object- and Self-Representation, Self and Object or Rivalry, and Intersubjective Communication. This approach attempts to understand twin relationships and the individual development of twins in terms of their intense mutual dependence, akin to infantile symbiosis, and in terms of narcissism. In their similarity to each other, twins may choose each other as love objects even as they see themselves in the other. That is, a twin may "love what he himself is" or "someone who was once part of himself." This "type of object-choice … must be termed 'narcissistic'" (Freud, 1914, pp. 90, 88). Such "cathexis of an undifferentiated self-object" is considered to be "primary narcissism" (Burstein, 1977, p. 103). Hoffer (1952) describes primary narcissism as "the lack of all qualities discriminating between self and not-self, inside and outside" (p. 33).

Metabolic co-dependence drives the evolutionarily ancient Hydra-Chlorella symbiosis.

PubMed

Hamada, Mayuko; Schröder, Katja; Bathia, Jay; Kürn, Ulrich; Fraune, Sebastian; Khalturina, Mariia; Khalturin, Konstantin; Shinzato, Chuya; Satoh, Nori; Bosch, Thomas Cg

2018-05-31

Many multicellular organisms rely on symbiotic associations for support of metabolic activity, protection, or energy. Understanding the mechanisms involved in controlling such interactions remains a major challenge. In an unbiased approach we identified key players that control the symbiosis between Hydra viridissima and its photosynthetic symbiont Chlorella sp. A99. We discovered significant up-regulation of Hydra genes encoding a phosphate transporter and glutamine synthetase suggesting regulated nutrition supply between host and symbionts. Interestingly, supplementing the medium with glutamine temporarily supports in vitro growth of the otherwise obligate symbiotic Chlorella , indicating loss of autonomy and dependence on the host. Genome sequencing of Chlorella sp. A99 revealed a large number of amino acid transporters and a degenerated nitrate assimilation pathway, presumably as consequence of the adaptation to the host environment. Our observations portray ancient symbiotic interactions as a codependent partnership in which exchange of nutrients appears to be the primary driving force. © 2018, Hamada et al.

Breakdown of the coral-algae symbiosis: towards formalising a linkage between warm-water bleaching thresholds and the growth rate of the intracellular zooxanthellae

NASA Astrophysics Data System (ADS)

Wooldridge, S. A.

2013-03-01

Impairment of the photosynthetic machinery of the algal endosymbiont ("zooxanthellae") is the proximal driver of the thermal breakdown of the coral-algae symbiosis ("coral bleaching"). Yet, the initial site of damage, and early dynamics of the impairment are still not well resolved. In this perspective essay, I consider further a recent hypothesis which proposes an energetic disruption to the carbon-concentrating mechanisms (CCMs) of the coral host, and the resultant onset of CO2-limitation within the photosynthetic "dark reactions" as a unifying cellular mechanism. The hypothesis identifies the enhanced retention of photosynthetic carbon for zooxanthellae (re)growth following an initial irradiance-driven expulsion event as a strong contributing cause of the energetic disruption. If true, then it implies that the onset of the bleaching syndrome and setting of upper thermal bleaching limits are emergent attributes of the coral symbiosis that are ultimately underpinned by the characteristic growth profile of the intracellular zooxanthellae; which is known to depend not just on temperature, but also external (seawater) nutrient availability and zooxanthellae genotype. Here, I review this proposed bleaching linkage at a variety of observational scales, and find it to be parsimonious with the available evidence. Future experiments are suggested that can more formally test the linkage. If correct, the new cellular model delivers a valuable new perspective to consider the future prospects of the coral symbiosis in an era of rapid environmental change, including: (i) the underpinning mechanics (and biological significance) of observed changes in resident zooxanthellae genotypes, and (ii) the now crucial importance of reef water quality in co-determining thermal bleaching resistance.

24-Epibrassinolide ameliorates salt stress effects in the symbiosis Medicago truncatula-Sinorhizobium meliloti and regulates the nodulation in cross-talk with polyamines.

PubMed

López-Gómez, Miguel; Hidalgo-Castellanos, Javier; Lluch, Carmen; Herrera-Cervera, José A

2016-11-01

Brassinosteroids (BRs) are steroid plant hormones that have been shown to be involved in the response to salt stress in cross-talk with other plant growth regulators such as polyamines (PAs). In addition, BRs are involved in the regulation of the nodulation in the rhizobium-legume symbiosis through the alteration of the PAs content in leaves. In this work, we have studied the effect of exogenous 24-epibrassinolide (EBL) in the response to salinity of nitrogen fixation in the symbiosis Medicago truncatula-Sinorhizobium meliloti. Foliar spraying of EBL restored the growth of plants subjected to salt stress and provoked an increment of the nitrogenase activity. In general, PAs levels in leaves and nodules decreased by the salt and EBL treatments, however, the co-treatment with NaCl and EBL augmented the foliar spermine (Spm) concentration. This increment of the Spm levels was followed by a reduction of the membrane oxidative damage and a diminution of the proline accumulation. The effect of BRs on the symbiotic interaction was evaluated by the addition of 0.01, 0.1 and 0.5 μM EBL to the growing solution, which provoked a reduction of the nodule number and an increment of the PAs levels in shoot. In conclusion, foliar treatment with EBL had a protective effect against salt stress in the M. truncatula-S. meliloti symbiosis mediated by an increment of the Spm levels. Treatment of roots with EBL incremented PAs levels in shoot and reduced the nodule number which suggests a cross-talk between PAs and BRs in the nodule suppression and the protection against salt stress. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Colonization State Influences the Hemocyte Proteome in a Beneficial Squid–Vibrio Symbiosis*

PubMed Central

Schleicher, Tyler R.; VerBerkmoes, Nathan C.; Shah, Manesh; Nyholm, Spencer V.

2014-01-01

The squid Euprymna scolopes and the luminescent bacterium Vibrio fischeri form a highly specific beneficial light organ symbiosis. Not only does the host have to select V. fischeri from the environment, but it must also prevent subsequent colonization by non-symbiotic microorganisms. Host macrophage-like hemocytes are believed to play a role in mediating the symbiosis with V. fischeri. Previous studies have shown that the colonization state of the light organ influences the host's hemocyte response to the symbiont. To further understand the molecular mechanisms behind this process, we used two quantitative mass-spectrometry-based proteomic techniques, isobaric tags for relative and absolute quantification (iTRAQ) and label-free spectral counting, to compare and quantify the adult hemocyte proteomes from colonized (sym) and uncolonized (antibiotic-treated/cured) squid. Overall, iTRAQ allowed for the quantification of 1,024 proteins with two or more peptides. Thirty-seven unique proteins were determined to be significantly different between sym and cured hemocytes (p value < 0.05), with 20 more abundant proteins and 17 less abundant in sym hemocytes. The label-free approach resulted in 1,241 proteins that were identified in all replicates. Of 185 unique proteins present at significantly different amounts in sym hemocytes (as determined by spectral counting), 92 were more abundant and 93 were less abundant. Comparisons between iTRAQ and spectral counting revealed that 30 of the 37 proteins quantified via iTRAQ exhibited trends similar to those identified by the label-free method. Both proteomic techniques mutually identified 16 proteins that were significantly different between the two groups of hemocytes (p value < 0.05). The presence of V. fischeri in the host light organ influenced the abundance of proteins associated with the cytoskeleton, adhesion, lysosomes, proteolysis, and the innate immune response. These data provide evidence that colonization by V. fischeri

Effector-Triggered Immunity Determines Host Genotype-Specific Incompatibility in Legume-Rhizobium Symbiosis.

PubMed

Yasuda, Michiko; Miwa, Hiroki; Masuda, Sachiko; Takebayashi, Yumiko; Sakakibara, Hitoshi; Okazaki, Shin

2016-08-01

Symbiosis between legumes and rhizobia leads to the formation of N2-fixing root nodules. In soybean, several host genes, referred to as Rj genes, control nodulation. Soybean cultivars carrying the Rj4 gene restrict nodulation by specific rhizobia such as Bradyrhizobium elkanii We previously reported that the restriction of nodulation was caused by B. elkanii possessing a functional type III secretion system (T3SS), which is known for its delivery of virulence factors by pathogenic bacteria. In the present study, we investigated the molecular basis for the T3SS-dependent nodulation restriction in Rj4 soybean. Inoculation tests revealed that soybean cultivar BARC-2 (Rj4/Rj4) restricted nodulation by B. elkanii USDA61, whereas its nearly isogenic line BARC-3 (rj4/rj4) formed nitrogen-fixing nodules with the same strain. Root-hair curling and infection threads were not observed in the roots of BARC-2 inoculated with USDA61, indicating that Rj4 blocked B. elkanii infection in the early stages. Accumulation of H2O2 and salicylic acid (SA) was observed in the roots of BARC-2 inoculated with USDA61. Transcriptome analyses revealed that inoculation of USDA61, but not its T3SS mutant in BARC-2, induced defense-related genes, including those coding for hypersensitive-induced responsive protein, which act in effector-triggered immunity (ETI) in Arabidopsis. These findings suggest that B. elkanii T3SS triggers the SA-mediated ETI-type response in Rj4 soybean, which consequently blocks symbiotic interactions. This study revealed a common molecular mechanism underlying both plant-pathogen and plant-symbiont interactions, and suggests that establishment of a root nodule symbiosis requires the evasion or suppression of plant immune responses triggered by rhizobial effectors. © The Author 2016. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Discovery of chemoautotrophic symbiosis in the giant shipworm Kuphus polythalamia (Bivalvia: Teredinidae) extends wooden-steps theory

PubMed Central

Altamia, Marvin A.; Lin, Zhenjian; Shipway, J. Reuben; Han, Andrew; Forteza, Imelda; Antemano, Rowena; Limbaco, Ma. Gwen J. Peñaflor; Dechavez, Rande; Albano, Julie; Rosenberg, Gary; Concepcion, Gisela P.; Schmidt, Eric W.; Haygood, Margo G.

2017-01-01

The “wooden-steps” hypothesis [Distel DL, et al. (2000) Nature 403:725–726] proposed that large chemosynthetic mussels found at deep-sea hydrothermal vents descend from much smaller species associated with sunken wood and other organic deposits, and that the endosymbionts of these progenitors made use of hydrogen sulfide from biogenic sources (e.g., decaying wood) rather than from vent fluids. Here, we show that wood has served not only as a stepping stone between habitats but also as a bridge between heterotrophic and chemoautotrophic symbiosis for the giant mud-boring bivalve Kuphus polythalamia. This rare and enigmatic species, which achieves the greatest length of any extant bivalve, is the only described member of the wood-boring bivalve family Teredinidae (shipworms) that burrows in marine sediments rather than wood. We show that K. polythalamia harbors sulfur-oxidizing chemoautotrophic (thioautotrophic) bacteria instead of the cellulolytic symbionts that allow other shipworm species to consume wood as food. The characteristics of its symbionts, its phylogenetic position within Teredinidae, the reduction of its digestive system by comparison with other family members, and the loss of morphological features associated with wood digestion indicate that K. polythalamia is a chemoautotrophic bivalve descended from wood-feeding (xylotrophic) ancestors. This is an example in which a chemoautotrophic endosymbiosis arose by displacement of an ancestral heterotrophic symbiosis and a report of pure culture of a thioautotrophic endosymbiont. PMID:28416684

Litter-forager termite mounds enhance the ectomycorrhizal symbiosis between Acacia holosericea A. Cunn. Ex G. Don and Scleroderma dictyosporum isolates.

PubMed

Duponnois, Robin; Assikbetse, Komi; Ramanankierana, Heriniaina; Kisa, Marija; Thioulouse, Jean; Lepage, Michel

2006-05-01

The hypothesis of the present study was that the termite mounds of Macrotermes subhyalinus (MS) (a litter-forager termite) were inhabited by a specific microflora that could enhance with the ectomycorrhizal fungal development. We tested the effect of this feeding group mound material on (i) the ectomycorrhization symbiosis between Acacia holosericea (an Australian Acacia introduced in the sahelian areas) and two ectomycorrhizal fungal isolates of Scleroderma dictyosporum (IR408 and IR412) in greenhouse conditions, (ii) the functional diversity of soil microflora and (iii) the diversity of fluorescent pseudomonads. The results showed that the termite mound amendment significantly increased the ectomycorrhizal expansion. MS mound amendment and ectomycorrhizal inoculation induced strong modifications of the soil functional microbial diversity by promoting the multiplication of carboxylic acid catabolizing microorganisms. The phylogenetic analysis showed that fluorescent pseudomonads mostly belong to the Pseudomonads monteillii species. One of these, P. monteillii isolate KR9, increased the ectomycorrhizal development between S. dictyosporum IR412 and A. holosericea. The occurrence of MS termite mounds could be involved in the expansion of ectomycorrhizal symbiosis and could be implicated in nutrient flow and local diversity.

Ocean acidification alters fish–jellyfish symbiosis

PubMed Central

Nagelkerken, Ivan; Pitt, Kylie A.; Rutte, Melchior D.; Geertsma, Robbert C.

2016-01-01

Symbiotic relationships are common in nature, and are important for individual fitness and sustaining species populations. Global change is rapidly altering environmental conditions, but, with the exception of coral–microalgae interactions, we know little of how this will affect symbiotic relationships. We here test how the effects of ocean acidification, from rising anthropogenic CO2 emissions, may alter symbiotic interactions between juvenile fish and their jellyfish hosts. Fishes treated with elevated seawater CO2 concentrations, as forecast for the end of the century on a business-as-usual greenhouse gas emission scenario, were negatively affected in their behaviour. The total time that fish (yellowtail scad) spent close to their jellyfish host in a choice arena where they could see and smell their host was approximately three times shorter under future compared with ambient CO2 conditions. Likewise, the mean number of attempts to associate with jellyfish was almost three times lower in CO2-treated compared with control fish, while only 63% (high CO2) versus 86% (control) of all individuals tested initiated an association at all. By contrast, none of three fish species tested were attracted solely to jellyfish olfactory cues under present-day CO2 conditions, suggesting that the altered fish–jellyfish association is not driven by negative effects of ocean acidification on olfaction. Because shelter is not widely available in the open water column and larvae of many (and often commercially important) pelagic species associate with jellyfish for protection against predators, modification of the fish–jellyfish symbiosis might lead to higher mortality and alter species population dynamics, and potentially have flow-on effects for their fisheries. PMID:27358374

Ocean acidification alters fish-jellyfish symbiosis.

PubMed

Nagelkerken, Ivan; Pitt, Kylie A; Rutte, Melchior D; Geertsma, Robbert C

2016-06-29

Symbiotic relationships are common in nature, and are important for individual fitness and sustaining species populations. Global change is rapidly altering environmental conditions, but, with the exception of coral-microalgae interactions, we know little of how this will affect symbiotic relationships. We here test how the effects of ocean acidification, from rising anthropogenic CO2 emissions, may alter symbiotic interactions between juvenile fish and their jellyfish hosts. Fishes treated with elevated seawater CO2 concentrations, as forecast for the end of the century on a business-as-usual greenhouse gas emission scenario, were negatively affected in their behaviour. The total time that fish (yellowtail scad) spent close to their jellyfish host in a choice arena where they could see and smell their host was approximately three times shorter under future compared with ambient CO2 conditions. Likewise, the mean number of attempts to associate with jellyfish was almost three times lower in CO2-treated compared with control fish, while only 63% (high CO2) versus 86% (control) of all individuals tested initiated an association at all. By contrast, none of three fish species tested were attracted solely to jellyfish olfactory cues under present-day CO2 conditions, suggesting that the altered fish-jellyfish association is not driven by negative effects of ocean acidification on olfaction. Because shelter is not widely available in the open water column and larvae of many (and often commercially important) pelagic species associate with jellyfish for protection against predators, modification of the fish-jellyfish symbiosis might lead to higher mortality and alter species population dynamics, and potentially have flow-on effects for their fisheries. © 2016 The Author(s).

The DivJ, CbrA and PleC system controls DivK phosphorylation and symbiosis in Sinorhizobium meliloti

PubMed Central

Pini, Francesco; Frage, Benjamin; Ferri, Lorenzo; De Nisco, Nicole J.; Mohapatra, Saswat S.; Taddei, Lucilla; Fioravanti, Antonella; Dewitte, Frederique; Galardini, Marco; Brilli, Matteo; Villeret, Vincent; Bazzicalupo, Marco; Mengoni, Alessio; Walker, Graham C.; Becker, Anke; Biondi, Emanuele G.

2013-01-01

SUMMARY Sinorhizobium meliloti is a soil bacterium that invades the root nodules it induces on Medicago sativa, whereupon it undergoes an alteration of its cell cycle and differentiates into nitrogen-fixing, elongated and polyploid bacteroid with higher membrane permeability. In Caulobacter crescentus, a related alphaproteobacterium, the principal cell cycle regulator, CtrA, is inhibited by the phosphorylated response regulator DivK. The phosphorylation of DivK depends on the histidine kinase DivJ, while PleC is the principal phosphatase for DivK. Despite the importance of the DivJ in C. crescentus, the mechanistic role of this kinase has never been elucidated in other Alphaproteobacteria. We show here that the histidine kinases DivJ together with CbrA and PleC participate in a complex phosphorylation system of the essential response regulator DivK in S. meliloti. In particular, DivJ and CbrA are involved in DivK phosphorylation and in turn CtrA inactivation, thereby controlling correct cell cycle progression and the integrity of the cell envelope. In contrast, the essential PleC presumably acts as a phosphatase of DivK. Interestingly, we found that a DivJ mutant is able to elicit nodules and enter plant cells, but fails to establish an effective symbiosis suggesting that proper envelope and/or low CtrA levels are required for symbiosis. PMID:23909720

Effects of multiple climate change factors on the tall fescue-fungal endophyte symbiosis: infection frequency and tissue chemistry.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brosi, Glade; McCulley, Rebecca L; Bush, L P

Climate change (altered CO{sub 2}, warming, and precipitation) may affect plant-microbial interactions, such as the Lolium arundinaceum-Neotyphodium coenophialum symbiosis, to alter future ecosystem structure and function. To assess this possibility, tall fescue tillers were collected from an existing climate manipulation experiment in a constructed old-field community in Tennessee (USA). Endophyte infection frequency (EIF) was determined, and infected (E+) and uninfected (E-) tillers were analysed for tissue chemistry. The EIF of tall fescue was higher under elevated CO{sub 2} (91% infected) than with ambient CO{sub 2} (81%) but was not affected by warming or precipitation treatments. Within E+ tillers, elevated CO{submore » 2} decreased alkaloid concentrations of both ergovaline and loline, by c. 30%; whereas warming increased loline concentrations 28% but had no effect on ergovaline. Independent of endophyte infection, elevated CO{sub 2} reduced concentrations of nitrogen, cellulose, hemicellulose, and lignin. These results suggest that elevated CO{sub 2}, more than changes in temperature or precipitation, may promote this grass-fungal symbiosis, leading to higher EIF in tall fescue in old-field communities. However, as all three climate factors are likely to change in the future, predicting the symbiotic response and resulting ecological consequences may be difficult and dependent on the specific atmospheric and climatic conditions encountered.« less

Plant lectins: the ties that bind in root symbiosis and plant defense.

PubMed

De Hoff, Peter L; Brill, Laurence M; Hirsch, Ann M

2009-07-01

Lectins are a diverse group of carbohydrate-binding proteins that are found within and associated with organisms from all kingdoms of life. Several different classes of plant lectins serve a diverse array of functions. The most prominent of these include participation in plant defense against predators and pathogens and involvement in symbiotic interactions between host plants and symbiotic microbes, including mycorrhizal fungi and nitrogen-fixing rhizobia. Extensive biological, biochemical, and molecular studies have shed light on the functions of plant lectins, and a plethora of uncharacterized lectin genes are being revealed at the genomic scale, suggesting unexplored and novel diversity in plant lectin structure and function. Integration of the results from these different types of research is beginning to yield a more detailed understanding of the function of lectins in symbiosis, defense, and plant biology in general.

Arbuscular mycorrhizal symbiosis elicits shoot proteome changes that are modified during cadmium stress alleviation in Medicago truncatula

PubMed Central

2011-01-01

Background Arbuscular mycorrhizal (AM) fungi, which engage a mutualistic symbiosis with the roots of most plant species, have received much attention for their ability to alleviate heavy metal stress in plants, including cadmium (Cd). While the molecular bases of Cd tolerance displayed by mycorrhizal plants have been extensively analysed in roots, very little is known regarding the mechanisms by which legume aboveground organs can escape metal toxicity upon AM symbiosis. As a model system to address this question, we used Glomus irregulare-colonised Medicago truncatula plants, which were previously shown to accumulate and tolerate heavy metal in their shoots when grown in a substrate spiked with 2 mg Cd kg-1. Results The measurement of three indicators for metal phytoextraction showed that shoots of mycorrhizal M. truncatula plants have a capacity for extracting Cd that is not related to an increase in root-to-shoot translocation rate, but to a high level of allocation plasticity. When analysing the photosynthetic performance in metal-treated mycorrhizal plants relative to those only Cd-supplied, it turned out that the presence of G. irregulare partially alleviated the negative effects of Cd on photosynthesis. To test the mechanisms by which shoots of Cd-treated mycorrhizal plants avoid metal toxicity, we performed a 2-DE/MALDI/TOF-based comparative proteomic analysis of the M. truncatula shoot responses upon mycorrhization and Cd exposure. Whereas the metal-responsive shoot proteins currently identified in non-mycorrhizal M. truncatula indicated that Cd impaired CO2 assimilation, the mycorrhiza-responsive shoot proteome was characterised by an increase in photosynthesis-related proteins coupled to a reduction in glugoneogenesis/glycolysis and antioxidant processes. By contrast, Cd was found to trigger the opposite response coupled the up-accumulation of molecular chaperones in shoot of mycorrhizal plants relative to those metal-free. Conclusion Besides drawing a

Polyamines contribute to salinity tolerance in the symbiosis Medicago truncatula-Sinorhizobium meliloti by preventing oxidative damage.

PubMed

López-Gómez, Miguel; Hidalgo-Castellanos, Javier; Muñoz-Sánchez, J Rubén; Marín-Peña, Agustín J; Lluch, Carmen; Herrera-Cervera, José A

2017-07-01

Polyamines (PAs) such as spermidine (Spd) and spermine (Spm) are small ubiquitous polycationic compounds that contribute to plant adaptation to salt stress. The positive effect of PAs has been associated to a cross-talk with other anti-stress hormones such as brassinosteroids (BRs). In this work we have studied the effects of exogenous Spd and Spm pre-treatments in the response to salt stress of the symbiotic interaction between Medicago truncatula and Sinorhizobium meliloti by analyzing parameters related to nitrogen fixation, oxidative damage and cross-talk with BRs in the response to salinity. Exogenous PAs treatments incremented the foliar and nodular Spd and Spm content which correlated with an increment of the nodule biomass and nitrogenase activity. Exogenous Spm treatment partially prevented proline accumulation which suggests that this polyamine could replace the role of this amino acid in the salt stress response. Additionally, Spd and Spm pre-treatments reduced the levels of H 2 O 2 and lipid peroxidation under salt stress. PAs induced the expression of genes involved in BRs biosynthesis which support a cross-talk between PAs and BRs in the salt stress response of M. truncatula-S. meliloti symbiosis. In conclusion, exogenous PAs improved the response to salinity of the M. truncatula-S. meliloti symbiosis by reducing the oxidative damage induced under salt stress conditions. In addition, in this work we provide evidences of the cross-talk between PAs and BRs in the adaptive responses to salinity. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Bacterial Diets of Primary Consumers at Hydrothermal Vents

NASA Astrophysics Data System (ADS)

Govenar, B.; Shank, T. M.

2008-12-01

Chemical energy produced by mixing hydrothermal fluids and seawater supports dense biological communities on mid-ocean ridges. The base of the food web at deep-sea hydrothermal vents is formed by chemolithoautotrophic bacteria that use the energy from the oxidation of reduced chemicals to fix inorganic carbon into simple sugars. With the exception of a few species that have chemolithoautotropic bacterial symbionts, most of the vent-endemic macrofauna are heterotrophs that feed on free-living bacteria, protists, and other invertebrates. The most abundant and diverse group of primary consumers in hydrothermal vent communities belong to the Gastropoda, particularly the patellomorph limpets. Gastropod densities can be as high as 2000 individuals m-2, and there can be as many as 13 species of gastropods in a single aggregation of the siboglinid tubeworm Riftia pachyptila and more than 40 species along the East Pacific Rise. Some gastropods are ubiquitous and others are found in specific microhabitats, stages of succession, or associated with different foundation species. To determine the mechanisms of species coexistence (e.g. resource partitioning or competition) among hydrothermal vent primary consumers and to track the flow of energy in hydrothermal vent communities, we employed molecular genetic techniques to identify the gut contents of four species of co-occurring hydrothermal vent gastropods, Eulepetopsis vitrea, Lepetodrilus elevatus, Lepetodrilus ovalis and Lepetodrilus pustulosus, collected from a single diffuse-flow hydrothermal vent site on the East Pacific Rise. Unique haplotypes of the 16S gene that fell among the epsilon-proteobacteria were found in the guts of every species, and two species had gut contents that were similar only to epsilon-proteobacteria. Two species had gut contents that also included haplotypes that clustered with delta-proteobacteria, and one species had gut contents that clustered with alpha- proteobacteria. Differences in the diets

Petunia as model for elucidating adventitious root formation and mycorrhizal symbiosis: at the nexus of physiology, genetics, microbiology and horticulture.

PubMed

Druege, Uwe; Franken, Philipp

2018-05-17

Adventitious root formation in cuttings and establishment of arbuscular mycorrhizal symbiosis reflect the enormous plasticity of plants and are key factors in the efficient and sustainable clonal propagation and production of ornamental crops. Based on the high importance of Petunia hybrida for the European and US annual bedding plant markets and its suitability as a model for basic plant sciences, petunia has been established as an experimental system for elucidating the molecular and physiological processes underlying adventitious root formation and mycorrhizal symbiosis. In the present review, we introduce the tools of the Petunia model system. Then, we discuss findings regarding the hormonal and metabolic control of adventitious rooting in the context of diverse environmental factors as well as findings on the function of arbuscular mycorrhiza related to nutrient uptake and resistance to root pathogens. Considering the recent publication of the genomes of the parental species of P. hybrida and other tools available in the petunia scientific community, we will outline the quality of petunia as a model for future system-oriented analysis of root development and function in the context of environmental and genetic control, which are at the heart of modern horticulture. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Symbiosis regulation in a facultatively symbiotic temperate coral: zooxanthellae division and expulsion

NASA Astrophysics Data System (ADS)

Dimond, J.; Carrington, E.

2008-09-01

Zooxanthellae mitotic index (MI) and expulsion rates were measured in the facultatively symbiotic scleractinian Astrangia poculata during winter and summer off the southern New England coast, USA. While MI was significantly higher in summer than in winter, mean expulsion rates were comparable between seasons. Corals therefore appear to allow increases in symbiont density when symbiosis is advantageous during the warm season, followed by a net reduction during the cold season when zooxanthellae may draw resources from the coral. Given previous reports that photosynthesis in A. poculata symbionts does not occur below approximately 6°C, considerable zooxanthellae division at 3°C and in darkness suggests that zooxanthellae are heterotrophic at low seasonal temperatures. Finally, examination of expulsion as a function of zooxanthellae density revealed that corals with very low zooxanthellae densities export a significantly greater proportion of their symbionts, apparently allowing them to persist in a stable azooxanthellate state.

Respiratory ATP cost and benefit of arbuscular mycorrhizal symbiosis with Nicotiana tabacum at different growth stages and under salinity.

PubMed

Del-Saz, Néstor Fernández; Romero-Munar, Antonia; Alonso, David; Aroca, Ricardo; Baraza, Elena; Flexas, Jaume; Ribas-Carbo, Miquel

2017-11-01

Growth and maintenance partly depend on both respiration and ATP production during oxidative phosphorylation in leaves. Under stress, ATP is needed to maintain the accumulated biomass. ATP production mostly proceeds from the cytochrome oxidase pathway (COP), while respiration via the alternative oxidase pathway (AOP) may decrease the production of ATP per oxygen consumed, especially under phosphorus (P) limitation and salinity conditions. Symbiosis with arbuscular mycorrhizal (AM) fungi is reputed by their positive effect on plant growth under stress at mature stages of colonization; however, fungal colonization may decrease plant growth at early stages. Thus, the present research is based on the hypothesis that AM fungus colonization will increase both foliar respiration and ATP production at mature stages of plant growth while decreasing them both at early stages. We used the oxygen-isotope-fractionation technique to study the in vivo respiratory activities and ATP production of the COP and AOP in AM and non-AM (NM) tobacco plants grown under P-limiting and saline conditions in sand at different growth stages (14, 28 and 49days). Our results suggest that AM symbiosis represents an ATP cost detrimental for shoot growth at early stages, whilst it represents a benefit on ATP allowing for faster rates of growth at mature stages, even under salinity conditions. Copyright © 2017 Elsevier GmbH. All rights reserved.

Integrated multi-omics analysis supports role of lysophosphatidylcholine and related glycerophospholipids in the Lotus japonicus-Glomus intraradices mycorrhizal symbiosis.

PubMed

Vijayakumar, Vinod; Liebisch, Gerhard; Buer, Benjamin; Xue, Li; Gerlach, Nina; Blau, Samira; Schmitz, Jessica; Bucher, Marcel

2016-02-01

Interaction of plant roots with arbuscular mycorrhizal fungi (AMF) is a complex trait resulting in cooperative interactions among the two symbionts including bidirectional exchange of resources. To study arbuscular mycorrhizal symbiosis (AMS) trait variation in the model plant Lotus japonicus, we performed an integrated multi-omics analysis with a focus on plant and fungal phospholipid (PL) metabolism and biological significance of lysophosphatidylcholine (LPC). Our results support the role of LPC as a bioactive compound eliciting cellular and molecular response mechanisms in Lotus. Evidence is provided for large interspecific chemical diversity of LPC species among mycorrhizae with related AMF species. Lipid, gene expression and elemental profiling emphasize the Lotus-Glomus intraradices interaction as distinct from other arbuscular mycorrhizal (AM) interactions. In G. intraradices, genes involved in fatty acid (FA) elongation and biosynthesis of unsaturated FAs were enhanced, while in Lotus, FA synthesis genes were up-regulated during AMS. Furthermore, FAS protein localization to mitochondria suggests FA biosynthesis and elongation may also occur in AMF. Our results suggest the existence of interspecific partitioning of PL resources for generation of LPC and novel candidate bioactive PLs in the Lotus-G. intraradices symbiosis. Moreover, the data advocate research with phylogenetically diverse Glomeromycota species for a broader understanding of the molecular underpinnings of AMS. © 2015 John Wiley & Sons Ltd.

Algal ancestor of land plants was preadapted for symbiosis.

PubMed

Delaux, Pierre-Marc; Radhakrishnan, Guru V; Jayaraman, Dhileepkumar; Cheema, Jitender; Malbreil, Mathilde; Volkening, Jeremy D; Sekimoto, Hiroyuki; Nishiyama, Tomoaki; Melkonian, Michael; Pokorny, Lisa; Rothfels, Carl J; Sederoff, Heike Winter; Stevenson, Dennis W; Surek, Barbara; Zhang, Yong; Sussman, Michael R; Dunand, Christophe; Morris, Richard J; Roux, Christophe; Wong, Gane Ka-Shu; Oldroyd, Giles E D; Ané, Jean-Michel

2015-10-27

Colonization of land by plants was a major transition on Earth, but the developmental and genetic innovations required for this transition remain unknown. Physiological studies and the fossil record strongly suggest that the ability of the first land plants to form symbiotic associations with beneficial fungi was one of these critical innovations. In angiosperms, genes required for the perception and transduction of diffusible fungal signals for root colonization and for nutrient exchange have been characterized. However, the origin of these genes and their potential correlation with land colonization remain elusive. A comprehensive phylogenetic analysis of 259 transcriptomes and 10 green algal and basal land plant genomes, coupled with the characterization of the evolutionary path leading to the appearance of a key regulator, a calcium- and calmodulin-dependent protein kinase, showed that the symbiotic signaling pathway predated the first land plants. In contrast, downstream genes required for root colonization and their specific expression pattern probably appeared subsequent to the colonization of land. We conclude that the most recent common ancestor of extant land plants and green algae was preadapted for symbiotic associations. Subsequent improvement of this precursor stage in early land plants through rounds of gene duplication led to the acquisition of additional pathways and the ability to form a fully functional arbuscular mycorrhizal symbiosis.

[Signaling Systems of Rhizobia (Rhizobiaceae) and Leguminous Plants (Fabaceae) upon the Formation of a Legume-Rhizobium Symbiosis (Review)].

PubMed

Glyan'ko, A K

2015-01-01

Data from the literature and our own data on the participation and interrelation of bacterial signaling Nod-factors and components of the calcium, NADPH-oxidase, and NO-synthase signaling systems of a plant at the preinfection and infectious stages of the formation of a legume-rhizobium symbiosis are summarized in this review. The physiological role of Nod-factors, reactive oxygen species (ROS), calcium (Ca2+), NADPH-oxidase, nitric oxide (NO), and their cross influence on the processes determining the formation of symbiotic structures on the roots of the host plant is discussed.

The Micro-RNA172c-APETALA2-1 Node as a Key Regulator of the Common Bean-Rhizobium etli Nitrogen Fixation Symbiosis1[OPEN

PubMed Central

Nova-Franco, Bárbara; Íñiguez, Luis P.; Valdés-López, Oswaldo; Leija, Alfonso; Fuentes, Sara I.; Ramírez, Mario; Paul, Sujay

2015-01-01

Micro-RNAs are recognized as important posttranscriptional regulators in plants. The relevance of micro-RNAs as regulators of the legume-rhizobia nitrogen-fixing symbiosis is emerging. The objective of this work was to functionally characterize the role of micro-RNA172 (miR172) and its conserved target APETALA2 (AP2) transcription factor in the common bean (Phaseolus vulgaris)-Rhizobium etli symbiosis. Our expression analysis revealed that mature miR172c increased upon rhizobial infection and continued increasing during nodule development, reaching its maximum in mature nodules and decaying in senescent nodules. The expression of AP2-1 target showed a negative correlation with miR172c expression. A drastic decrease in miR172c and high AP2-1 mRNA levels were observed in ineffective nodules. Phenotypic analysis of composite bean plants with transgenic roots overexpressing miR172c or a mutated AP2-1 insensitive to miR172c cleavage demonstrated the pivotal regulatory role of the miR172 node in the common bean-rhizobia symbiosis. Increased miR172 resulted in improved root growth, increased rhizobial infection, increased expression of early nodulation and autoregulation of nodulation genes, and improved nodulation and nitrogen fixation. In addition, these plants showed decreased sensitivity to nitrate inhibition of nodulation. Through transcriptome analysis, we identified 114 common bean genes that coexpressed with AP2-1 and proposed these as being targets for transcriptional activation by AP2-1. Several of these genes are related to nodule senescence, and we propose that they have to be silenced, through miR172c-induced AP2-1 cleavage, in active mature nodules. Our work sets the basis for exploring the miR172-mediated improvement of symbiotic nitrogen fixation in common bean, the most important grain legume for human consumption. PMID:25739700

Role of the Sinorhizobium meliloti Global Regulator Hfq in Gene Regulation and Symbiosis

PubMed Central

Long, Sharon R.; Teplitski, Max

2016-01-01

The RNA-binding protein Hfq is a global regulator which controls diverse cellular processes in bacteria. To begin understanding the role of Hfq in the Sinorhizobium meliloti–Medicago truncatula nitrogen-fixing symbiosis, we defined free-living and symbiotic phenotypes of an hfq mutant. Over 500 transcripts were differentially accumulated in the hfq mutant of S. meliloti Rm1021 when grown in a shaking culture. Consistent with transcriptome-wide changes, the hfq mutant displayed dramatic alterations in metabolism of nitrogen-containing compounds, even though its carbon source utilization profiles were nearly identical to the wild type. The hfq mutant had reduced motility and was impaired for growth at alkaline pH. A deletion of hfq resulted in a reduced symbiotic efficiency, although the mutant was still able to initiate nodule development and differentiate into bacteroids. PMID:20192823

Microbial fuel cells for robotics: energy autonomy through artificial symbiosis.

PubMed

Ieropoulos, Ioannis A; Greenman, John; Melhuish, Chris; Horsfield, Ian

2012-06-01

The development of the microbial fuel cell (MFC) technology has seen an enormous growth over the last hundred years since its inception by Potter in 1911. The technology has reached a level of maturity that it is now considered to be a field in its own right with a growing scientific community. The highest level of activity has been recorded over the last decade and it is perhaps considered commonplace that MFCs are primarily suitable for stationary, passive wastewater treatment applications. Sceptics have certainly not considered MFCs as serious contenders in the race for developing renewable energy technologies. Yet this is the only type of alternative system that can convert organic waste-widely distributed around the globe-directly into electricity, and therefore, the only technology that will allow artificial agents to autonomously operate in a plethora of environments. This Minireview describes the history and current state-of-the-art regarding MFCs in robotics and their vital role in artificial symbiosis and autonomy. Furthermore, the article demonstrates how pursuing practical robotic applications can provide insights of the core MFC technology in general. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The micro-RNA72c-APETALA2-1 node as a key regulator of the common bean-Rhizobium etli nitrogen fixation symbiosis.

PubMed

Nova-Franco, Bárbara; Íñiguez, Luis P; Valdés-López, Oswaldo; Alvarado-Affantranger, Xochitl; Leija, Alfonso; Fuentes, Sara I; Ramírez, Mario; Paul, Sujay; Reyes, José L; Girard, Lourdes; Hernández, Georgina

2015-05-01

Micro-RNAs are recognized as important posttranscriptional regulators in plants. The relevance of micro-RNAs as regulators of the legume-rhizobia nitrogen-fixing symbiosis is emerging. The objective of this work was to functionally characterize the role of micro-RNA172 (miR172) and its conserved target APETALA2 (AP2) transcription factor in the common bean (Phaseolus vulgaris)-Rhizobium etli symbiosis. Our expression analysis revealed that mature miR172c increased upon rhizobial infection and continued increasing during nodule development, reaching its maximum in mature nodules and decaying in senescent nodules. The expression of AP2-1 target showed a negative correlation with miR172c expression. A drastic decrease in miR172c and high AP2-1 mRNA levels were observed in ineffective nodules. Phenotypic analysis of composite bean plants with transgenic roots overexpressing miR172c or a mutated AP2-1 insensitive to miR172c cleavage demonstrated the pivotal regulatory role of the miR172 node in the common bean-rhizobia symbiosis. Increased miR172 resulted in improved root growth, increased rhizobial infection, increased expression of early nodulation and autoregulation of nodulation genes, and improved nodulation and nitrogen fixation. In addition, these plants showed decreased sensitivity to nitrate inhibition of nodulation. Through transcriptome analysis, we identified 114 common bean genes that coexpressed with AP2-1 and proposed these as being targets for transcriptional activation by AP2-1. Several of these genes are related to nodule senescence, and we propose that they have to be silenced, through miR172c-induced AP2-1 cleavage, in active mature nodules. Our work sets the basis for exploring the miR172-mediated improvement of symbiotic nitrogen fixation in common bean, the most important grain legume for human consumption. © 2015 American Society of Plant Biologists. All Rights Reserved.

Rhizobacteria and plant symbiosis in heavy metal uptake and its implications for soil bioremediation.

PubMed

Sobariu, Dana Luminița; Fertu, Daniela Ionela Tudorache; Diaconu, Mariana; Pavel, Lucian Vasile; Hlihor, Raluca-Maria; Drăgoi, Elena Niculina; Curteanu, Silvia; Lenz, Markus; Corvini, Philippe François-Xavier; Gavrilescu, Maria

2017-10-25

Certain species of plants can benefit from synergistic effects with plant growth-promoting rhizobacteria (PGPR) that improve plant growth and metal accumulation, mitigating toxic effects on plants and increasing their tolerance to heavy metals. The application of PGPR as biofertilizers and atmospheric nitrogen fixators contributes considerably to the intensification of the phytoremediation process. In this paper, we have built a system consisting of rhizospheric Azotobacter microbial populations and Lepidium sativum plants, growing in solutions containing heavy metals in various concentrations. We examined the ability of the organisms to grow in symbiosis so as to stimulate the plant growth and enhance its tolerance to Cr(VI) and Cd(II), to ultimately provide a reliable phytoremediation system. The study was developed at the laboratory level and, at this stage, does not assess the inherent interactions under real conditions occurring in contaminated fields with autochthonous microflora and under different pedoclimatic conditions and environmental stresses. Azotobacter sp. bacteria could indeed stimulate the average germination efficiency of Lepidium sativum by almost 7%, average root length by 22%, average stem length by 34% and dry biomass by 53%. The growth of L. sativum has been affected to a greater extent in Cd(II) solutions due its higher toxicity compared to that of Cr(VI). The reduced tolerance index (TI, %) indicated that plant growth in symbiosis with PGPR was however affected by heavy metal toxicity, while the tolerance of the plant to heavy metals was enhanced in the bacteria-plant system. A methodology based on artificial neural networks (ANNs) and differential evolution (DE), specifically a neuro-evolutionary approach, was applied to model germination rates, dry biomass and root/stem length and proving the robustness of the experimental data. The errors associated with all four variables are small and the correlation coefficients higher than 0

Neo-Symbiosis: The Next Stage in the Evolution of Human Information Interaction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Griffith, Douglas; Greitzer, Frank L.

We re-address the vision of human-computer symbiosis expressed by J. C. R. Licklider nearly a half-century ago, when he wrote: “The hope is that in not too many years, human brains and computing machines will be coupled together very tightly, and that the resulting partnership will think as no human brain has ever thought and process data in a way not approached by the information-handling machines we know today.” (Licklider, 1960). Unfortunately, little progress was made toward this vision over four decades following Licklider’s challenge, despite significant advancements in the fields of human factors and computer science. Licklider’s vision wasmore » largely forgotten. However, recent advances in information science and technology, psychology, and neuroscience have rekindled the potential of making the Licklider’s vision a reality. This paper provides a historical context for and updates the vision, and it argues that such a vision is needed as a unifying framework for advancing IS&T.« less

Repeated replacement of an intrabacterial symbiont in the tripartite nested mealybug symbiosis

PubMed Central

Husnik, Filip; McCutcheon, John P.

2016-01-01

Stable endosymbiosis of a bacterium into a host cell promotes cellular and genomic complexity. The mealybug Planococcus citri has two bacterial endosymbionts with an unusual nested arrangement: the γ-proteobacterium Moranella endobia lives in the cytoplasm of the β-proteobacterium Tremblaya princeps. These two bacteria, along with genes horizontally transferred from other bacteria to the P. citri genome, encode gene sets that form an interdependent metabolic patchwork. Here, we test the stability of this three-way symbiosis by sequencing host and symbiont genomes for five diverse mealybug species and find marked fluidity over evolutionary time. Although Tremblaya is the result of a single infection in the ancestor of mealybugs, the γ-proteobacterial symbionts result from multiple replacements of inferred different ages from related but distinct bacterial lineages. Our data show that symbiont replacement can happen even in the most intricate symbiotic arrangements and that preexisting horizontally transferred genes can remain stable on genomes in the face of extensive symbiont turnover. PMID:27573819

Rhizobial infection does not require cortical expression of upstream common symbiosis genes responsible for the induction of Ca(2+) spiking.

PubMed

Hayashi, Teruyuki; Shimoda, Yoshikazu; Sato, Shusei; Tabata, Satoshi; Imaizumi-Anraku, Haruko; Hayashi, Makoto

2014-01-01

For the establishment of an effective root nodule symbiosis, a coordinated regulation of the infection processes between the epidermis and cortex is required. However, it remains unclear whether the symbiotic genes identified so far are involved in epidermal and/or cortical infection, e.g. epidermal and cortical infection thread formation or cortical cell division. To analyze the symbiotic gene requirements of the infection process, we have developed an epidermis-specific expression system (pEpi expression system) and examined the symbiotic genes NFR1, NFR5, NUP85, NUP133, CASTOR, POLLUX, CCaMK, CYCLOPS, NSP1 and NSP2 for involvement in the infection process in the epidermis and cortex. Our study shows that expression of the upstream common symbiosis genes CASTOR, POLLUX, NUP85 and NUP133 in the epidermis is sufficient to induce formation of infection threads and cortical cell division, leading to the development of fully effective nodules. Our system also shows a requirement of CCaMK, CYCLOPS, NSP1 and NSP2 for the entire nodulation process, and the different contributions of NFR1 and NFR5 to cortical infection thread formation. Based on these analyses using the pEpi expression system, we propose a functional model of symbiotic genes for epidermal and cortical infection. © 2013 The Authors The Plant Journal © 2013 John Wiley & Sons Ltd.

Tsetse-Wolbachia symbiosis: Comes of age and has great potential for pest and disease control

PubMed Central

Doudoumis, Vangelis; Alam, Uzma; Aksoy, Emre; Abd-Alla, Adly M.M.; Tsiamis, George; Brelsfoard, Corey; Aksoy, Serap; Bourtzis, Kostas

2013-01-01

Tsetse flies (Diptera: Glossinidae) are the sole vectors of African trypanosomes, the causative agent of sleeping sickness in human and nagana in animals. Like most eukaryotic organisms, Glossina species have established symbiotic associations with bacteria. Three main symbiotic bacteria have been found in tsetse flies: Wigglesworthia glossinidia, an obligate symbiotic bacterium, the secondary endosymbiont Sodalis glossinidius and the reproductive symbiont Wolbachia pipientis. In the present review, we discuss recent studies on the detection and characterization of Wolbachia infections in Glossina species, the horizontal transfer of Wolbachia genes to tsetse chromosomes, the ability of this symbiont to induce cytoplasmic incompatibility in Glossina morsitans morsitans and also how new environment-friendly tools for disease control could be developed by harnessing Wolbachia symbiosis. PMID:22835476

High phosphate reduces host ability to develop arbuscular mycorrhizal symbiosis without affecting root calcium spiking responses to the fungus

PubMed Central

Balzergue, Coline; Chabaud, Mireille; Barker, David G.; Bécard, Guillaume; Rochange, Soizic F.

2013-01-01

The arbuscular mycorrhizal symbiosis associates soil fungi with the roots of the majority of plants species and represents a major source of soil phosphorus acquisition. Mycorrhizal interactions begin with an exchange of molecular signals between the two partners. A root signaling pathway is recruited, for which the perception of fungal signals triggers oscillations of intracellular calcium concentration. High phosphate availability is known to inhibit the establishment and/or persistence of this symbiosis, thereby favoring the direct, non-symbiotic uptake of phosphorus by the root system. In this study, Medicago truncatula plants were used to investigate the effects of phosphate supply on the early stages of the interaction. When plants were supplied with high phosphate fungal attachment to the roots was drastically reduced. An experimental system was designed to individually study the effects of phosphate supply on the fungus, on the roots, and on root exudates. These experiments revealed that the most important effects of high phosphate supply were on the roots themselves, which became unable to host mycorrhizal fungi even when these had been appropriately stimulated. The ability of the roots to perceive their fungal partner was then investigated by monitoring nuclear calcium spiking in response to fungal signals. This response did not appear to be affected by high phosphate supply. In conclusion, high levels of phosphate predominantly impact the plant host, but apparently not in its ability to perceive the fungal partner. PMID:24194742

Glomus fasciculatum Fungi as a Bio-convertor and Bio-activator of Inorganic and Organic P in Dual Symbiosis.

PubMed

Azmat, Rafia; Hamid, Neelofer; Moin, Sumeira; Saleem, Ailyan

2016-01-01

Dual symbiosis played an effective role in drought condition and temperature. Furthermore, performed services in absorption of water and solubilization of chief nutrients specially phosphorus for growth of plants. Phosphorous is essential for plant growth in any climatic condition because of central constituent of ATP providing chemical energy for all metabolic reactions of plants. The goal of this work was to monitor the growth of plant under three climatic conditions in comparison to control plant under Glomus fasciculatum inoculation related with adequate supply of phosphorous. Results demonstrated that Glomus fasciculatum (VAM) activates the solubilization of P into the anionic form H2PO4(-) which is highly consumable form by the plants. Minerals including P in soil most regularly solubilized for fixing in plants and continuously changed to highly soluble forms by reaction with inorganic or organic constituents of the soil which are activated in the presence of fungi for continuous availability. Experimental facts and nonstop growth of plants recommended that VAM fungi act as a bio-convertor and bio-activator of soil nutrients, especially of P and their hyphal interaction absorbs soil nutrients and activates insoluble P to soluble one for plant development. Continuous growth of 18 months old Conocarpus erectus L plant in dual symbiosis supports the proposed idea that phosphorus cycle exists during VAM inoculations, where soil reaction altered in presence of spores that help to solubilize the P which strengthens the plant, activates photo-biological activity and demonstrates the new function of VAM as a recycler for continues growth.

Differential effects of rare specific flavonoids on compatible and incompatible strains in the Myrica gale-Frankia actinorhizal symbiosis.

PubMed

Popovici, Jean; Comte, Gilles; Bagnarol, Emilie; Alloisio, Nicole; Fournier, Pascale; Bellvert, Floriant; Bertrand, Cédric; Fernandez, Maria P

2010-04-01

Plant secondary metabolites, and specifically phenolics, play important roles when plants interact with their environment and can act as weapons or positive signals during biotic interactions. One such interaction, the establishment of mutualistic nitrogen-fixing symbioses, typically involves phenolic-based recognition mechanisms between host plants and bacterial symbionts during the early stages of interaction. While these mechanisms are well studied in the rhizobia-legume symbiosis, little is known about the role of plant phenolics in the symbiosis between actinorhizal plants and Frankia genus strains. In this study, the responsiveness of Frankia strains to plant phenolics was correlated with their symbiotic compatibility. We used Myrica gale, a host species with narrow symbiont specificity, and a set of compatible and noncompatible Frankia strains. M. gale fruit exudate phenolics were extracted, and 8 dominant molecules were purified and identified as flavonoids by high-resolution spectroscopic techniques. Total fruit exudates, along with two purified dihydrochalcone molecules, induced modifications of bacterial growth and nitrogen fixation according to the symbiotic specificity of strains, enhancing compatible strains and inhibiting incompatible ones. Candidate genes involved in these effects were identified by a global transcriptomic approach using ACN14a strain whole-genome microarrays. Fruit exudates induced differential expression of 22 genes involved mostly in oxidative stress response and drug resistance, along with the overexpression of a whiB transcriptional regulator. This work provides evidence for the involvement of plant secondary metabolites in determining symbiotic specificity and expands our understanding of the mechanisms, leading to the establishment of actinorhizal symbioses.

Characterization of soybean β-expansin genes and their expression responses to symbiosis, nutrient deficiency, and hormone treatment.

PubMed

Li, Xinxin; Zhao, Jing; Walk, Thomas C; Liao, Hong

2014-03-01

Expansins are plant cell wall-loosening proteins encoded by a superfamily of genes including α-expansin, β-expansin, expansin-like A, and expansin-like B proteins. They play a variety of biological roles during plant growth and development. Expansin genes have been reported in many plant species, and results primarily from graminaceous members indicate that β-expansins are more abundant in monocots than in dicots. Soybean [Glycine max (L.) Merr] is an important legume crop. This work identified nine β-expansin gene family members in soybean (GmEXPBs) that were divided into two distinct classes based on phylogeny and gene structure, with divergence between the two groups occurring more in introns than in exons. A total of 887 hormone-responsive and environmental stress-related putative cis-elements from 188 families were found in the 2-kb upstream region of GmEXPBs. Variations in number and type of cis-elements associated with each gene indicate that the function of these genes is differentially regulated by these signals. Expression analysis confirmed that the family members were ubiquitously, yet differentially expressed in soybean. Responsiveness to nutrient deficiency stresses and regulation by auxin (indole-3-acetic acid) and cytokinin (6-benzylaminopurine) varied among GmEXPBs. In addition, most β-expansin genes were associated with symbiosis of soybean inoculated with Rhizobium or abuscular mycorrhizal fungi (AMF). Taken together, these results systematically investigate the characteristics of the entire GmEXPB family in soybean and comprise the first report analyzing the relationship of GmEXPBs with rhizobial or AMF symbiosis. This information is a valuable step in the process of understanding the expansin protein functions in soybean and opens avenues for continued researches.

The characterization of six auxin-induced tomato GH3 genes uncovers a member, SlGH3.4, strongly responsive to arbuscular mycorrhizal symbiosis.

PubMed

Liao, Dehua; Chen, Xiao; Chen, Aiqun; Wang, Huimin; Liu, Jianjian; Liu, Junli; Gu, Mian; Sun, Shubin; Xu, Guohua

2015-04-01

In plants, the GH3 gene family is widely considered to be involved in a broad range of plant physiological processes, through modulation of hormonal homeostasis. Multiple GH3 genes have been functionally characterized in several plant species; however, to date, limited works to study the GH3 genes in tomato have been reported. Here, we characterize the expression and regulatory profiles of six tomato GH3 genes, SlGH3.2, SlGH3.3, SlGH3.4, SlGH3.7, SlGH3.9 and SlGH3.15, in response to different phytohormone applications and arbuscular mycorrhizal (AM) fungal colonization. All six GH3 genes showed inducible responses to external IAA, and three members were significantly up-regulated in response to AM symbiosis. In particular, SlGH3.4, the transcripts of which were barely detectable under normal growth conditions, was strongly activated in the IAA-treated and AM fungal-colonized roots. A comparison of the SlGH3.4 expression in wild-type plants and M161, a mutant with a defect in AM symbiosis, confirmed that SlGH3.4 expression is highly correlated to mycorrhizal colonization. Histochemical staining demonstrated that a 2,258 bp SlGH3.4 promoter fragment could drive β-glucuronidase (GUS) expression strongly in root tips, steles and cortical cells of IAA-treated roots, but predominantly in the fungal-colonized cells of mycorrhizal roots. A truncated 654 bp promoter failed to direct GUS expression in IAA-treated roots, but maintained the symbiosis-induced activity in mycorrhizal roots. In summary, our results suggest that a mycorrhizal signaling pathway that is at least partially independent of the auxin signaling pathway has evolved for the co-regulation of the auxin- and mycorrhiza-activated GH3 genes in plants. © The Author 2014. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Shared Skeletal Support in a Coral-Hydroid Symbiosis

PubMed Central

Pantos, Olga; Hoegh-Guldberg, Ove

2011-01-01

Hydroids form symbiotic relationships with a range of invertebrate hosts. Where they live with colonial invertebrates such as corals or bryozoans the hydroids may benefit from the physical support and protection of their host's hard exoskeleton, but how they interact with them is unknown. Electron microscopy was used to investigate the physical interactions between the colonial hydroid Zanclea margaritae and its reef-building coral host Acropora muricata. The hydroid tissues extend below the coral tissue surface sitting in direct contact with the host's skeleton. Although this arrangement provides the hydroid with protective support, it also presents problems of potential interference with the coral's growth processes and exposes the hydroid to overgrowth and smothering. Desmocytes located within the epidermal layer of the hydroid's perisarc-free hydrorhizae fasten it to the coral skeleton. The large apical surface area of the desmocyte and high bifurcation of the distal end within the mesoglea, as well as the clustering of desmocytes suggests that a very strong attachment between the hydroid and the coral skeleton. This is the first study to provide a detailed description of how symbiotic hydroids attach to their host's skeleton, utilising it for physical support. Results suggest that the loss of perisarc, a characteristic commonly associated with symbiosis, allows the hydroid to utilise desmocytes for attachment. The use of these anchoring structures provides a dynamic method of attachment, facilitating detachment from the coral skeleton during extension, thereby avoiding overgrowth and smothering enabling the hydroid to remain within the host colony for prolonged periods of time. PMID:21695083

Stress tolerance in plants via habitat-adapted symbiosis

USGS Publications Warehouse

Rodriguez, R.J.; Henson, J.; Van Volkenburgh, E.; Hoy, M.; Wright, L.; Beckwith, F.; Kim, Y.-O.; Redman, R.S.

2008-01-01

We demonstrate that native grass species from coastal and geothermal habitats require symbiotic fungal endophytes for salt and heat tolerance, respectively. Symbiotically conferred stress tolerance is a habitat-specific phenomenon with geothermal endophytes conferring heat but not salt tolerance, and coastal endophytes conferring salt but not heat tolerance. The same fungal species isolated from plants in habitats devoid of salt or heat stress did not confer these stress tolerances. Moreover, fungal endophytes from agricultural crops conferred disease resistance and not salt or heat tolerance. We define habitat-specific, symbiotically-conferred stress tolerance as habitat-adapted symbiosis and hypothesize that it is responsible for the establishment of plants in high-stress habitats. The agricultural, coastal and geothermal plant endophytes also colonized tomato (a model eudicot) and conferred disease, salt and heat tolerance, respectively. In addition, the coastal plant endophyte colonized rice (a model monocot) and conferred salt tolerance. These endophytes have a broad host range encompassing both monocots and eudicots. Interestingly, the endophytes also conferred drought tolerance to plants regardless of the habitat of origin. Abiotic stress tolerance correlated either with a decrease in water consumption or reactive oxygen sensitivity/generation but not to increased osmolyte production. The ability of fungal endophytes to confer stress tolerance to plants may provide a novel strategy for mitigating the impacts of global climate change on agricultural and native plant communities.The ISME Journal (2008) 2, 404-416; doi:10.1038/ismej.2007.106; published online 7 February 2008. ?? 2008 International Society for Microbial Ecology All rights reserved.

Arbuscular mycorrhizal symbiosis affects the grain proteome of Zea mays: a field study

PubMed Central

Bona, Elisa; Scarafoni, Alessio; Marsano, Francesco; Boatti, Lara; Copetta, Andrea; Massa, Nadia; Gamalero, Elisa; D’Agostino, Giovanni; Cesaro, Patrizia; Cavaletto, Maria; Berta, Graziella

2016-01-01

Maize is one of the most important crops worldwide and is strongly dependent on arbuscular mycorrhiza (AM) fungi, organisms that form a mutualistic association with land plants. In maize, AM symbiosis enhances spike dry weight, spike length, spike circumference, and the dry weight and dimensions of the grain. Notwithstanding its ubiquitous nature, the detailed relationship between AM fungal colonization and plant development is not completely understood. To facilitate a better understanding of the effects of AM fungi on plants, the work reported here assessed the effects of a consortium of AM fungi on the kernel proteome of maize, cultivated in open-field conditions. To our knowledge, this is the first report of the modulation of a plant seed proteome following AM fungal inoculation in the field. Here, it was found that AM fungi modify the maize seed proteome by up-regulating enzymes involved in energetic metabolism, embryo development, nucleotide metabolism, seed storage and stress responses. PMID:27216714

The relationship between thiamine and two symbioses: Root nodule symbiosis and arbuscular mycorrhiza.

PubMed

Nagae, Miwa; Parniske, Martin; Kawaguchi, Masayoshi; Takeda, Naoya

2016-12-01

Lotus japonicus THIC is expressed in all organs, and the encoded protein catalyzes thiamine biosynthesis. Loss of function produces chlorosis, a typical thiamine-deficiency phenotype, and mortality. To investigate thiamine's role in symbiosis, we focused on THI1, a thiamine-biosynthesis gene expressed in roots, nodules, and seeds. The thi1 mutant had green leaves, but formed small nodules and immature seeds. These phenotypes were rescued by THI1 complementation and by exogenous thiamine. Thus, THI1 is required for nodule enlargement and seed maturation. On the other hand, colonization by arbuscular mycorrhiza (AM) fungus Rhizophagus irregularis was not affected in the thi1 mutant or by exogenous thiamine. However, spores of R. irregularis stored more thiamine than the source (host plants), despite lacking thiamine biosynthesis genes. Therefore, disturbance of the thiamine supply would affect progeny phenotypes such as spore formation and hyphal growth. Further investigation will be required to elucidate thiamine's effect on AM.

Arbuscular mycorrhizal symbiosis affects the grain proteome of Zea mays: a field study.

PubMed

Bona, Elisa; Scarafoni, Alessio; Marsano, Francesco; Boatti, Lara; Copetta, Andrea; Massa, Nadia; Gamalero, Elisa; D'Agostino, Giovanni; Cesaro, Patrizia; Cavaletto, Maria; Berta, Graziella

2016-05-24

Maize is one of the most important crops worldwide and is strongly dependent on arbuscular mycorrhiza (AM) fungi, organisms that form a mutualistic association with land plants. In maize, AM symbiosis enhances spike dry weight, spike length, spike circumference, and the dry weight and dimensions of the grain. Notwithstanding its ubiquitous nature, the detailed relationship between AM fungal colonization and plant development is not completely understood. To facilitate a better understanding of the effects of AM fungi on plants, the work reported here assessed the effects of a consortium of AM fungi on the kernel proteome of maize, cultivated in open-field conditions. To our knowledge, this is the first report of the modulation of a plant seed proteome following AM fungal inoculation in the field. Here, it was found that AM fungi modify the maize seed proteome by up-regulating enzymes involved in energetic metabolism, embryo development, nucleotide metabolism, seed storage and stress responses.

Tsetse-Wolbachia symbiosis: comes of age and has great potential for pest and disease control.

PubMed

Doudoumis, Vangelis; Alam, Uzma; Aksoy, Emre; Abd-Alla, Adly M M; Tsiamis, George; Brelsfoard, Corey; Aksoy, Serap; Bourtzis, Kostas

2013-03-01

Tsetse flies (Diptera: Glossinidae) are the sole vectors of African trypanosomes, the causative agent of sleeping sickness in human and nagana in animals. Like most eukaryotic organisms, Glossina species have established symbiotic associations with bacteria. Three main symbiotic bacteria have been found in tsetse flies: Wigglesworthia glossinidia, an obligate symbiotic bacterium, the secondary endosymbiont Sodalis glossinidius and the reproductive symbiont Wolbachia pipientis. In the present review, we discuss recent studies on the detection and characterization of Wolbachia infections in Glossina species, the horizontal transfer of Wolbachia genes to tsetse chromosomes, the ability of this symbiont to induce cytoplasmic incompatibility in Glossina morsitans morsitans and also how new environment-friendly tools for disease control could be developed by harnessing Wolbachia symbiosis. Copyright © 2012 International Atomic Energy Agency. Published by Elsevier Inc. All rights reserved.

Effect of bacterial root symbiosis and urea as source of nitrogen on performance of soybean plants grown hydroponically for Bioregenerative Life Support Systems (BLSSs)

PubMed Central

Paradiso, Roberta; Buonomo, Roberta; Dixon, Mike A.; Barbieri, Giancarlo; De Pascale, Stefania

2015-01-01

Soybean is traditionally grown in soil, where root symbiosis with Bradyrhizobium japonicum can supply nitrogen (N), by means of bacterial fixation of atmospheric N2. Nitrogen fertilizers inhibit N-fixing bacteria. However, urea is profitably used in soybean cultivation in soil, where urease enzymes of telluric microbes catalyze the hydrolysis to ammonium, which has a lighter inhibitory effect compared to nitrate. Previous researches demonstrated that soybean can be grown hydroponically with recirculating complete nitrate-based nutrient solutions. In Space, urea derived from crew urine could be used as N source, with positive effects in resource procurement and waste recycling. However, whether the plants are able to use urea as the sole source of N and its effect on root symbiosis with B. japonicum is still unclear in hydroponics. We compared the effect of two N sources, nitrate and urea, on plant growth and physiology, and seed yield and quality of soybean grown in closed-loop Nutrient Film Technique (NFT) in growth chamber, with or without inoculation with B. japonicum. Urea limited plant growth and seed yield compared to nitrate by determining nutrient deficiency, due to its low utilization efficiency in the early developmental stages, and reduced nutrients uptake (K, Ca, and Mg) throughout the whole growing cycle. Root inoculation with B. japonicum did not improve plant performance, regardless of the N source. Specifically, nodulation increased under fertigation with urea compared to nitrate, but this effect did not result in higher leaf N content and better biomass and seed production. Urea was not suitable as sole N source for soybean in closed-loop NFT. However, the ability to use urea increased from young to adult plants, suggesting the possibility to apply it during reproductive phase or in combination with nitrate in earlier developmental stages. Root symbiosis did not contribute significantly to N nutrition and did not enhance the plant ability to use

Live imaging of symbiosis: spatiotemporal infection dynamics of a GFP-labelled Burkholderia symbiont in the bean bug Riptortus pedestris

PubMed Central

Kikuchi, Yoshitomo; Fukatsu, Takema

2014-01-01

Many insects possess endosymbiotic bacteria inside their body, wherein intimate interactions occur between the partners. While recent technological advancements have deepened our understanding of metabolic and evolutionary features of the symbiont genomes, molecular mechanisms underpinning the intimate interactions remain difficult to approach because the insect symbionts are generally uncultivable. The bean bug Riptortus pedestris is associated with the betaproteobacterial Burkholderia symbiont in a posterior region of the midgut, which develops numerous crypts harbouring the symbiont extracellularly. Distinct from other insect symbiotic systems, R. pedestris acquires the Burkholderia symbiont not by vertical transmission but from the environment every generation. By making use of the cultivability and the genetic tractability of the symbiont, we constructed a transgenic Burkholderia strain labelled with green fluorescent protein (GFP), which enabled detailed observation of spatiotemporal dynamics and the colonization process of the symbiont in freshly prepared specimens. The symbiont live imaging revealed that, at the second instar, colonization of the symbiotic midgut M4 region started around 6 h after inoculation (hai). By 24 hai, the symbiont cells appeared in the main tract and also in several crypts of the M4. By 48 hai, most of the crypts were colonized by the symbiont cells. By 72 hai, all the crypts were filled up with the symbiont cells and the symbiont localization pattern continued during the subsequent nymphal development. Quantitative PCR of the symbiont confirmed the infection dynamics quantitatively. These results highlight the stinkbug-Burkholderia gut symbiosis as an unprecedented model for comprehensive understanding of molecular mechanisms underpinning insect symbiosis. PMID:24103110

Developing the anemone Aiptasia as a tractable model for cnidarian-dinoflagellate symbiosis: the transcriptome of aposymbiotic A. pallida.

PubMed

Lehnert, Erik M; Burriesci, Matthew S; Pringle, John R

2012-06-22

Coral reefs are hotspots of oceanic biodiversity, forming the foundation of ecosystems that are important both ecologically and for their direct practical impacts on humans. Corals are declining globally due to a number of stressors, including rising sea-surface temperatures and pollution; such stresses can lead to a breakdown of the essential symbiotic relationship between the coral host and its endosymbiotic dinoflagellates, a process known as coral bleaching. Although the environmental stresses causing this breakdown are largely known, the cellular mechanisms of symbiosis establishment, maintenance, and breakdown are still largely obscure. Investigating the symbiosis using an experimentally tractable model organism, such as the small sea anemone Aiptasia, should improve our understanding of exactly how the environmental stressors affect coral survival and growth. We assembled the transcriptome of a clonal population of adult, aposymbiotic (dinoflagellate-free) Aiptasia pallida from ~208 million reads, yielding 58,018 contigs. We demonstrated that many of these contigs represent full-length or near-full-length transcripts that encode proteins similar to those from a diverse array of pathways in other organisms, including various metabolic enzymes, cytoskeletal proteins, and neuropeptide precursors. The contigs were annotated by sequence similarity, assigned GO terms, and scanned for conserved protein domains. We analyzed the frequency and types of single-nucleotide variants and estimated the size of the Aiptasia genome to be ~421 Mb. The contigs and annotations are available through NCBI (Transcription Shotgun Assembly database, accession numbers JV077153-JV134524) and at http://pringlelab.stanford.edu/projects.html. The availability of an extensive transcriptome assembly for A. pallida will facilitate analyses of gene-expression changes, identification of proteins of interest, and other studies in this important emerging model system.

Comparative Genomics Reveals the Core Gene Toolbox for the Fungus-Insect Symbiosis.

PubMed

Wang, Yan; Stata, Matt; Wang, Wei; Stajich, Jason E; White, Merlin M; Moncalvo, Jean-Marc

2018-05-15

Modern genomics has shed light on many entomopathogenic fungi and expanded our knowledge widely; however, little is known about the genomic features of the insect-commensal fungi. Harpellales are obligate commensals living in the digestive tracts of disease-bearing insects (black flies, midges, and mosquitoes). In this study, we produced and annotated whole-genome sequences of nine Harpellales taxa and conducted the first comparative analyses to infer the genomic diversity within the members of the Harpellales. The genomes of the insect gut fungi feature low (26% to 37%) GC content and large genome size variations (25 to 102 Mb). Further comparisons with insect-pathogenic fungi (from both Ascomycota and Zoopagomycota), as well as with free-living relatives (as negative controls), helped to identify a gene toolbox that is essential to the fungus-insect symbiosis. The results not only narrow the genomic scope of fungus-insect interactions from several thousands to eight core players but also distinguish host invasion strategies employed by insect pathogens and commensals. The genomic content suggests that insect commensal fungi rely mostly on adhesion protein anchors that target digestive system, while entomopathogenic fungi have higher numbers of transmembrane helices, signal peptides, and pathogen-host interaction (PHI) genes across the whole genome and enrich genes as well as functional domains to inactivate the host inflammation system and suppress the host defense. Phylogenomic analyses have revealed that genome sizes of Harpellales fungi vary among lineages with an integer-multiple pattern, which implies that ancient genome duplications may have occurred within the gut of insects. IMPORTANCE Insect guts harbor various microbes that are important for host digestion, immune response, and disease dispersal in certain cases. Bacteria, which are among the primary endosymbionts, have been studied extensively. However, fungi, which are also frequently encountered

Symbiosis between microorganisms from kombucha and kefir: Potential significance to the enhancement of kombucha function.

PubMed

Yang, Zhiwei; Zhou, Feng; Ji, Baoping; Li, Bo; Luo, Yangchao; Yang, Li; Li, Tao

2010-01-01

Gluconacetobacter sp. A4 (G. sp. A4), which had strong ability to produce d-saccharic acid 1, 4 lactone (DSL), was the key functional bacteria isolated from the kombucha preserved. This paper investigated the interaction between G. sp. A4 and ten different strains of lactic acid bacteria (LAB) obtained from kefir. The result suggested that the LAB promoted DSL production of G. sp. A4 to different extents, ranging from 4.86% to 86.70%. Symbiosis between G. sp. A4 and LAB was studied. LAB's metabolites, xylitol, and acetic acid, were utilized by G. sp. A4, and it promoted the growth of G. sp. A4 and yield of DSL. Therefore, in developing starter cultures for kombucha fermentation process, a mixed flora of LAB and G. sp. A4 would be the optimal combination.

Elemental stoichiometry indicates predominant influence of potassium and phosphorus limitation on arbuscular mycorrhizal symbiosis in acidic soil at high altitude.

PubMed

Khan, Mohammad Haneef; Meghvansi, Mukesh K; Gupta, Rajeev; Veer, Vijay

2015-09-15

The functioning of high-altitude agro-ecosystems is constrained by the harsh environmental conditions, such as low temperatures, acidic soil, and low nutrient supply. It is therefore imperative to investigate the site-specific ecological stoichiometry with respect to AM symbiosis in order to maximize the arbuscular mycorrhizal (AM) benefits for the plants in such ecosystems. Here, we assess the elemental stoichiometry of four Capsicum genotypes grown on acidic soil at high altitude in Arunachal Pradesh, India. Further, we try to identify the predominant resource limitations influencing the symbioses of different Capsicum genotypes with the AM fungi. Foliar and soil elemental stoichiometric relations of Capsicum genotypes were evaluated with arbuscular mycorrhizal (AM) colonization and occurrence under field conditions. AM fungal diversity in rhizosphere, was estimated through PCR-DGGE profiling. Results demonstrated that the symbiotic interaction of various Capsicum genotypes with the AM fungi in acidic soil was not prominent in the study site as evident from the low range of root colonization (21-43.67%). In addition, despite the rich availability of carbon in plant leaves as well as in soil, the carbon-for-phosphorus trade between AMF and plants appeared to be limited. Our results provide strong evidences of predominant influence of the potassium-limitation, in addition to phosphorus-limitation, on AM symbiosis with Capsicum in acidic soil at high altitude. We also conclude that the potassium should be considered in addition to carbon, nitrogen, and phosphorus in further studies investigating the stoichiometric relationships with the AMF symbioses in high altitude agro-ecosystems. Copyright © 2015 Elsevier GmbH. All rights reserved.

Transcriptional patterns in both host and bacterium underlie a daily rhythm of anatomical and metabolic change in a beneficial symbiosis.

PubMed

Wier, Andrew M; Nyholm, Spencer V; Mandel, Mark J; Massengo-Tiassé, R Prisca; Schaefer, Amy L; Koroleva, Irina; Splinter-Bondurant, Sandra; Brown, Bartley; Manzella, Liliana; Snir, Einat; Almabrazi, Hakeem; Scheetz, Todd E; Bonaldo, Maria de Fatima; Casavant, Thomas L; Soares, M Bento; Cronan, John E; Reed, Jennifer L; Ruby, Edward G; McFall-Ngai, Margaret J

2010-02-02

Mechanisms for controlling symbiont populations are critical for maintaining the associations that exist between a host and its microbial partners. We describe here the transcriptional, metabolic, and ultrastructural characteristics of a diel rhythm that occurs in the symbiosis between the squid Euprymna scolopes and the luminous bacterium Vibrio fischeri. The rhythm is driven by the host's expulsion from its light-emitting organ of most of the symbiont population each day at dawn. The transcriptomes of both the host epithelium that supports the symbionts and the symbiont population itself were characterized and compared at four times over this daily cycle. The greatest fluctuation in gene expression of both partners occurred as the day began. Most notable was an up-regulation in the host of >50 cytoskeleton-related genes just before dawn and their subsequent down-regulation within 6 h. Examination of the epithelium by TEM revealed a corresponding restructuring, characterized by effacement and blebbing of its apical surface. After the dawn expulsion, the epithelium reestablished its polarity, and the residual symbionts began growing, repopulating the light organ. Analysis of the symbiont transcriptome suggested that the bacteria respond to the effacement by up-regulating genes associated with anaerobic respiration of glycerol; supporting this finding, lipid analysis of the symbionts' membranes indicated a direct incorporation of host-derived fatty acids. After 12 h, the metabolic signature of the symbiont population shifted to one characteristic of chitin fermentation, which continued until the following dawn. Thus, the persistent maintenance of the squid-vibrio symbiosis is tied to a dynamic diel rhythm that involves both partners.

Transcriptomic changes in an animal-bacterial symbiosis under modeled microgravity conditions

PubMed Central

Casaburi, Giorgio; Goncharenko-Foster, Irina; Duscher, Alexandrea A.; Foster, Jamie S.

2017-01-01

Spaceflight imposes numerous adaptive challenges for terrestrial life. The reduction in gravity, or microgravity, represents a novel environment that can disrupt homeostasis of many physiological processes. Additionally, it is becoming increasingly clear that an organism’s microbiome is critical for host health and examining its resiliency in microgravity represents a new frontier for space biology research. In this study, we examine the impact of microgravity on the interactions between the squid Euprymna scolopes and its beneficial symbiont Vibrio fischeri, which form a highly specific binary mutualism. First, animals inoculated with V. fischeri aboard the space shuttle showed effective colonization of the host light organ, the site of the symbiosis, during space flight. Second, RNA-Seq analysis of squid exposed to modeled microgravity conditions exhibited extensive differential gene expression in the presence and absence of the symbiotic partner. Transcriptomic analyses revealed in the absence of the symbiont during modeled microgravity there was an enrichment of genes and pathways associated with the innate immune and oxidative stress response. The results suggest that V. fischeri may help modulate the host stress responses under modeled microgravity. This study provides a window into the adaptive responses that the host animal and its symbiont use during modeled microgravity. PMID:28393904

Possible Benefits of Mycorrhizal Symbiosis, in Reducing CO2 from Environment

NASA Astrophysics Data System (ADS)

Azmat, Rafia

2013-12-01

It is a fact that the relationship between a fungus and a plant can have a great impact on the environment, especially under drought conditions. Experiments conducted at the laboratory scale suggested that in mycorrhizal symbiosis; plants usually provide their fungal partners with carbohydrates from photosynthesis and receive mineral nutrients. It is observed that mycorrhizal inoculated plants observed large surface area of leaves and outsized root sections which were helpful in increasing the rate of photosynthetic processes. This may be attributed to the rapid production of carbohydrate for their fungal mate. The same phenomena can be observed in environments of high traffic density or waste burning, industrial zones (where there are emissions of CO2 from chimneys) or the areas that are lack nutrients such as nitrogen and phosphorus. It may be observed that the plants that have this association with mycorrhizal fungi may obligate a better chance in inhabiting this area. These plants can be helpful in reducing the CO2 from the polluted atmosphere. The large length of the roots were related to the absorption of water molecules for survival as well as formation of first organic complex CHO for providing the energy to the plant in biotic stress and C and nutrient exchange between fungal partner and plants.

(Iron regulation of gene expression in the Bradyrhizobium japonicum/soybean symbiosis)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guerinot, M.L.

We wish to address the question of whether iron plays a regulatory role in the Bradyrhizobium japonicum/soybeam symbiosis. Iron may be an important regulatory signal in planta as the bacteria must acquire iron from their plant hosts and iron-containing proteins figure prominently in all nitrogen-fixing symbioses. For example, the bacterial partner is believed to synthesize the heme moiety of leghemoglobin, which may represent as much as 25--30% of the total soluble protein in an infected plant cell. For this reason, we have focused our attention on the regulation by iron of the first step in the bacterial heme biosynthetic pathway.more » The enzyme which catalyzes this step, 5-aminolevulinic acid synthase, is encoded by the hemA gene which we had previously cloned and sequenced. Specific objectives include: to define the cis-acting sequences which confer iron regulation on the B. japonicum hemA gene; to identify trans-acting factors which regulate the expression of hemA by iron; to identify new loci which are transcriptionally responsive to changes in iron availability; and to examine the effects of mutations in various known regulatory genes for their effect on the expression of hemA.« less

Fungal symbiosis from mutualism to parasitism: who controls the outcome, host or invader?

USGS Publications Warehouse

Redman, R.S.; Dunigan, D.D.; Rodriguez, R.J.

2001-01-01

Plant symbiotic fungi are generally thought to express a single lifestyle that might increase (mutualism), decrease (parasitism), or have no influence (commensalism) on host fitness. However, data are presented here demonstrating that plant pathogenic Colletotrichum species are able to asymptomatically colonize plants and express nonpathogenic lifestyles. Experiments were conducted in growth chambers and plant colonization was assessed by emergence of fungi from surface sterilized plant tissues. Expression of symbiotic lifestyles was assessed by monitoring the ability of fungi to confer disease resistance, drought tolerance and growth enhancement. Several pathogenic Colletotrichum species expressed either mutualistic or commensal lifestyles in plants not known to be hosts. Mutualists conferred disease resistance, drought tolerance, and/or growth enhancement to host plants. Lifestyle-altered mutants expressing nonpathogenic lifestyles had greater host ranges than the parental wildtype isolate. Successive colonization studies indicated that the ability of a symbiont to colonize a plant was dependent on previous colonization events and the lifestyles expressed by the initial colonizing fungus. The results indicate that the outcome of symbiosis is controlled by the plant's physiology. ?? New Phytologist.

Upscaling Arbuscular Mycorrhizal Symbiosis and Related Agroecosystems Services in Smallholder Farming Systems

PubMed Central

Oruru, Marjorie Bonareri; Njeru, Ezekiel Mugendi

2016-01-01

Smallholder farming systems form unique ecosystems that can protect beneficial soil biota and form an important source of useful genetic resources. They are characterized by high level of agricultural diversity mainly focused on meeting farmers' needs. Unfortunately, these systems often experience poor crop production mainly associated with poor planning and resource scarcity. Soil fertility is among the primary challenges faced by smallholder farmers, which necessitate the need to come up with affordable and innovative ways of replenishing soils. One such way is the use of microbial symbionts such as arbuscular mycorrhizal fungi (AMF), a beneficial group of soil microbiota that form symbiotic associations with majority of cultivated crops and play a vital role in biological soil fertility, plant nutrition, and protection. AMF can be incorporated in smallholder farming systems to help better exploit chemical fertilizers inputs which are often unaffordable to many smallholder farmers. The present review highlights smallholder farming practices that could be innovatively redesigned to increase AMF symbiosis and related agroecosystem services. Indeed, the future of global food security depends on the success of smallholder farming systems, whose crop productivity depends on the services provided by well-functioning ecosystems, including soil fertility. PMID:26942194

Arbuscular mycorrhiza Symbiosis Induces a Major Transcriptional Reprogramming of the Potato SWEET Sugar Transporter Family.

PubMed

Manck-Götzenberger, Jasmin; Requena, Natalia

2016-01-01

Biotrophic microbes feeding on plants must obtain carbon from their hosts without killing the cells. The symbiotic Arbuscular mycorrhizal (AM) fungi colonizing plant roots do so by inducing major transcriptional changes in the host that ultimately also reprogram the whole carbon partitioning of the plant. AM fungi obtain carbohydrates from the root cortex apoplast, in particular from the periarbuscular space that surrounds arbuscules. However, the mechanisms by which cortical cells export sugars into the apoplast for fungal nutrition are unknown. Recently a novel type of sugar transporter, the SWEET, able to perform not only uptake but also efflux from cells was identified. Plant SWEETs have been shown to be involved in the feeding of pathogenic microbes and are, therefore, good candidates to play a similar role in symbiotic associations. Here we have carried out the first phylogenetic and expression analyses of the potato SWEET family and investigated its role during mycorrhiza symbiosis. The potato genome contains 35 SWEETs that cluster into the same four clades defined in Arabidopsis. Colonization of potato roots by the AM fungus Rhizophagus irregularis imposes major transcriptional rewiring of the SWEET family involving, only in roots, changes in 22 of the 35 members. None of the SWEETs showed mycorrhiza-exclusive induction and most of the 12 induced genes belong to the putative hexose transporters of clade I and II, while only two are putative sucrose transporters from clade III. In contrast, most of the repressed transcripts (10) corresponded to clade III SWEETs. Promoter-reporter assays for three of the induced genes, each from one cluster, showed re-localization of expression to arbuscule-containing cells, supporting a role for SWEETs in the supply of sugars at biotrophic interfaces. The complex transcriptional regulation of SWEETs in roots in response to AM fungal colonization supports a model in which symplastic sucrose in cortical cells could be cleaved

Arbuscular mycorrhiza Symbiosis Induces a Major Transcriptional Reprogramming of the Potato SWEET Sugar Transporter Family

PubMed Central

Manck-Götzenberger, Jasmin; Requena, Natalia

2016-01-01

Biotrophic microbes feeding on plants must obtain carbon from their hosts without killing the cells. The symbiotic Arbuscular mycorrhizal (AM) fungi colonizing plant roots do so by inducing major transcriptional changes in the host that ultimately also reprogram the whole carbon partitioning of the plant. AM fungi obtain carbohydrates from the root cortex apoplast, in particular from the periarbuscular space that surrounds arbuscules. However, the mechanisms by which cortical cells export sugars into the apoplast for fungal nutrition are unknown. Recently a novel type of sugar transporter, the SWEET, able to perform not only uptake but also efflux from cells was identified. Plant SWEETs have been shown to be involved in the feeding of pathogenic microbes and are, therefore, good candidates to play a similar role in symbiotic associations. Here we have carried out the first phylogenetic and expression analyses of the potato SWEET family and investigated its role during mycorrhiza symbiosis. The potato genome contains 35 SWEETs that cluster into the same four clades defined in Arabidopsis. Colonization of potato roots by the AM fungus Rhizophagus irregularis imposes major transcriptional rewiring of the SWEET family involving, only in roots, changes in 22 of the 35 members. None of the SWEETs showed mycorrhiza-exclusive induction and most of the 12 induced genes belong to the putative hexose transporters of clade I and II, while only two are putative sucrose transporters from clade III. In contrast, most of the repressed transcripts (10) corresponded to clade III SWEETs. Promoter-reporter assays for three of the induced genes, each from one cluster, showed re-localization of expression to arbuscule-containing cells, supporting a role for SWEETs in the supply of sugars at biotrophic interfaces. The complex transcriptional regulation of SWEETs in roots in response to AM fungal colonization supports a model in which symplastic sucrose in cortical cells could be cleaved

Paracatenula, an ancient symbiosis between thiotrophic Alphaproteobacteria and catenulid flatworms

PubMed Central

Gruber-Vodicka, Harald Ronald; Dirks, Ulrich; Leisch, Nikolaus; Stoecker, Kilian; Bulgheresi, Silvia; Heindl, Niels Robert; Horn, Matthias; Lott, Christian; Loy, Alexander; Wagner, Michael; Ott, Jörg

2011-01-01

Harnessing chemosynthetic symbionts is a recurring evolutionary strategy. Eukaryotes from six phyla as well as one archaeon have acquired chemoautotrophic sulfur-oxidizing bacteria. In contrast to this broad host diversity, known bacterial partners apparently belong to two classes of bacteria—the Gamma- and Epsilonproteobacteria. Here, we characterize the intracellular endosymbionts of the mouthless catenulid flatworm genus Paracatenula as chemoautotrophic sulfur-oxidizing Alphaproteobacteria. The symbionts of Paracatenula galateia are provisionally classified as “Candidatus Riegeria galateiae” based on 16S ribosomal RNA sequencing confirmed by fluorescence in situ hybridization together with functional gene and sulfur metabolite evidence. 16S rRNA gene phylogenetic analysis shows that all 16 Paracatenula species examined harbor host species-specific intracellular Candidatus Riegeria bacteria that form a monophyletic group within the order Rhodospirillales. Comparing host and symbiont phylogenies reveals strict cocladogenesis and points to vertical transmission of the symbionts. Between 33% and 50% of the body volume of the various worm species is composed of bacterial symbionts, by far the highest proportion among all known endosymbiotic associations between bacteria and metazoans. This symbiosis, which likely originated more than 500 Mya during the early evolution of flatworms, is the oldest known animal–chemoautotrophic bacteria association. The distant phylogenetic position of the symbionts compared with other mutualistic or parasitic Alphaproteobacteria promises to illuminate the common genetic predispositions that have allowed several members of this class to successfully colonize eukaryote cells. PMID:21709249

Transcriptome analysis of the Populus trichocarpa-Rhizophagus irregularis Mycorrhizal Symbiosis: Regulation of Plant and Fungal Transportomes under Nitrogen Starvation.

PubMed

Calabrese, Silvia; Kohler, Annegret; Niehl, Annette; Veneault-Fourrey, Claire; Boller, Thomas; Courty, Pierre-Emmanuel

2017-06-01

Nutrient transfer is a key feature of the arbuscular mycorrhizal (AM) symbiosis. Valuable mineral nutrients are transferred from the AM fungus to the plant, increasing its fitness and productivity, and, in exchange, the AM fungus receives carbohydrates as an energy source from the plant. Here, we analyzed the transcriptome of the Populus trichocarpa-Rhizophagus irregularis symbiosis using RNA-sequencing of non-mycorrhizal or mycorrhizal fine roots, with a focus on the effect of nitrogen (N) starvation. In R. irregularis, we identified 1,015 differentially expressed genes, whereby N starvation led to a general induction of gene expression. Genes of the functional classes of cell growth, membrane biogenesis and cell structural components were highly abundant. Interestingly, N starvation also led to a general induction of fungal transporters, indicating increased nutrient demand upon N starvation. In non-mycorrhizal P. trichocarpa roots, 1,341 genes were differentially expressed under N starvation. Among the 953 down-regulated genes in N starvation, most were involved in metabolic processes including amino acids, carbohydrate and inorganic ion transport, while the 342 up-regulated genes included many defense-related genes. Mycorrhization led to the up-regulation of 549 genes mainly involved in secondary metabolite biosynthesis and transport; only 24 genes were down-regulated. Mycorrhization specifically induced expression of three ammonium transporters and one phosphate transporter, independently of the N conditions, corroborating the hypothesis that these transporters are important for symbiotic nutrient exchange. In conclusion, our data establish a framework of gene expression in the two symbiotic partners under high-N and low-N conditions. © The Author 2017. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Cyanobacteria produce a high variety of hepatotoxic peptides in lichen symbiosis

PubMed Central

Kaasalainen, Ulla; Fewer, David P.; Jokela, Jouni; Wahlsten, Matti; Sivonen, Kaarina; Rikkinen, Jouko

2012-01-01

Lichens are symbiotic associations between fungi and photosynthetic algae or cyanobacteria. Microcystins are potent toxins that are responsible for the poisoning of both humans and animals. These toxins are mainly associated with aquatic cyanobacterial blooms, but here we show that the cyanobacterial symbionts of terrestrial lichens from all over the world commonly produce microcystins. We screened 803 lichen specimens from five different continents for cyanobacterial toxins by amplifying a part of the gene cluster encoding the enzyme complex responsible for microcystin production and detecting toxins directly from lichen thalli. We found either the biosynthetic genes for making microcystins or the toxin itself in 12% of all analyzed lichen specimens. A plethora of different microcystins was found with over 50 chemical variants, and many of the variants detected have only rarely been reported from free-living cyanobacteria. In addition, high amounts of nodularin, up to 60 μg g−1, were detected from some lichen thalli. This microcystin analog and potent hepatotoxin has previously been known only from the aquatic bloom-forming genus Nodularia. Our results demonstrate that the production of cyanobacterial hepatotoxins in lichen symbiosis is a global phenomenon and occurs in many different lichen lineages. The very high genetic diversity of the mcyE gene and the chemical diversity of microcystins suggest that lichen symbioses may have been an important environment for diversification of these cyanobacteria. PMID:22451908

Media(ted) fabrications: how the science-media symbiosis helped 'sell' cord banking.

PubMed

Michelle, Carolyn

2006-01-01

This paper considers the problematic role of the science-media symbiosis in the dissemination of misleading and emotionally manipulative information regarding services offered by CordBank, New Zealand's only umbilical cord blood banking facility. As this case study illustrates, the growing reliance of health and science reporters on the knowledge capital of medical specialists, biogenetic researchers, and scientists potentially enhances the ability of 'expert' sources to set the agenda for media representations of emerging medical and scientific developments, and may undermine the editorial independence of journalists and editors, many of whom in this case failed to critically evaluate deeply problematic claims regarding the current and future benefits of cord banking. Heavy reliance on established media frames of anecdotal personalization and technoboosterism also reinforced a proscience journalistic culture in which claims by key sources were uncritically reiterated and amplified, with journalistic assessments of the value of cord banking emphasizing potential benefits for individual consumers. It is argued that use of these media frames potentially detracts from due consideration of the broader social, ethical, legal, and health implications of emerging biomedical developments, along with the professional, personal, and increasingly also financial interests at stake in their public promotion, given the growing commercialization of biogenetic technologies.

The jet-disk symbiosis without maximal jets: 1D hydrodynamical jets revisited

NASA Astrophysics Data System (ADS)

Crumley, Patrick; Ceccobello, Chiara; Connors, Riley M. T.; Cavecchi, Yuri

2017-05-01

In this work we discuss the recent criticism by Zdziarski (2016, A&A, 586, A18) of the maximal jet model derived in Falcke & Biermann (1995, A&A, 293, 665). We agree with Zdziarski that in general a jet's internal energy is not bounded by its rest-mass energy density. We describe the effects of the mistake on conclusions that have been made using the maximal jet model and show when a maximal jet is an appropriate assumption. The maximal jet model was used to derive a 1D hydrodynamical model of jets in agnjet, a model that does multiwavelength fitting of quiescent/hard state X-ray binaries and low-luminosity active galactic nuclei. We correct algebraic mistakes made in the derivation of the 1D Euler equation and relax the maximal jet assumption. We show that the corrections cause minor differences as long as the jet has a small opening angle and a small terminal Lorentz factor. We find that the major conclusion from the maximal jet model, the jet-disk symbiosis, can be generally applied to astrophysical jets. We also show that isothermal jets are required to match the flat radio spectra seen in low-luminosity X-ray binaries and active galactic nuclei, in agreement with other works.

Characterization and function of carbonic anhydrases in the zooxanthellae-giant clam symbiosis.

PubMed

Baillie, B K; Yellowlees, D

1998-03-22

Carbonic anhydrase (CA) has been purified from the host tissue of Tridacna gigas, a clam that lives in symbiosis with the dinoflagellate alga, Symbiodinium. At least two isoforms of CA were identified in both gill and mantle tissue. The larger (70 kDa) isoform is a glycoprotein with both N- and O-glycans attached and has highest homology to CAII. It is associated with the membrane fraction while the smaller (32 kDa) is present in the aqueous phase in both tissues. The 32 kDa CA has high homology with mammalian CAI at the N-terminus. Both isoforms cross-reacted with antibodies to CAII from chicken. Immunohistology demonstrated that the 70 kDa CA is present within the ciliated branchial filaments and cells lining the tertiary water channels in the gills of T. gigas. This is consistent with a role in the transport of inorganic carbon (Ci) to the haemolymph and therefore supply of Ci to the zooxanthellae. CA was also detected in mantle epithelial cells where it may also contribute to Ci supply to the zooxanthellae. The hyaline body and nerve tissue in the mantle express the 70 kDa CA where it may be involved in light sensing and nervous transmission.

Analysis of gene expression from the Wolbachia genome of a filarial nematode supports both metabolic and defensive roles within the symbiosis

PubMed Central

Darby, Alistair C.; Armstrong, Stuart D.; Bah, Germanus S.; Kaur, Gaganjot; Hughes, Margaret A.; Kay, Suzanne M.; Koldkjær, Pia; Rainbow, Lucille; Radford, Alan D.; Blaxter, Mark L.; Tanya, Vincent N.; Trees, Alexander J.; Cordaux, Richard; Wastling, Jonathan M.; Makepeace, Benjamin L.

2012-01-01

The α-proteobacterium Wolbachia is probably the most prevalent, vertically transmitted symbiont on Earth. In contrast with its wide distribution in arthropods, Wolbachia is restricted to one family of animal-parasitic nematodes, the Onchocercidae. This includes filarial pathogens such as Onchocerca volvulus, the cause of human onchocerciasis, or river blindness. The symbiosis between filariae and Wolbachia is obligate, although the basis of this dependency is not fully understood. Previous studies suggested that Wolbachia may provision metabolites (e.g., haem, riboflavin, and nucleotides) and/or contribute to immune defense. Importantly, Wolbachia is restricted to somatic tissues in adult male worms, whereas females also harbor bacteria in the germline. We sought to characterize the nature of the symbiosis between Wolbachia and O. ochengi, a bovine parasite representing the closest relative of O. volvulus. First, we sequenced the complete genome of Wolbachia strain wOo, which revealed an inability to synthesize riboflavin de novo. Using RNA-seq, we also generated endobacterial transcriptomes from male soma and female germline. In the soma, transcripts for membrane transport and respiration were up-regulated, while the gonad exhibited enrichment for DNA replication and translation. The most abundant Wolbachia proteins, as determined by geLC-MS, included ligands for mammalian Toll-like receptors. Enzymes involved in nucleotide synthesis were dominant among metabolism-related proteins, whereas the haem biosynthetic pathway was poorly represented. We conclude that Wolbachia may have a mitochondrion-like function in the soma, generating ATP for its host. Moreover, the abundance of immunogenic proteins in wOo suggests a role in diverting the immune system toward an ineffective antibacterial response. PMID:22919073

Phosphorus Acquisition Efficiency Related to Root Traits: Is Mycorrhizal Symbiosis a Key Factor to Wheat and Barley Cropping?

PubMed Central

Campos, Pedro; Borie, Fernando; Cornejo, Pablo; López-Ráez, Juan A.; López-García, Álvaro; Seguel, Alex

2018-01-01

Wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.) are major crops cultivated around the world, thus playing a crucial role on human diet. Remarkably, the growing human population requires a significant increase in agricultural production in order to feed everybody. In this context, phosphorus (P) management is a key factor as it is component of organic molecules such as nucleic acids, ATP and phospholipids, and it is the most abundant macronutrient in biomass after nitrogen (N), although being one of the scarcest elements in the lithosphere. In general, P fertilization has low efficiency, as only a fraction of the applied P is acquired by roots, leaving a substantial amount to be accumulated in soil as not readily available P. Breeding for P-efficient cultivars is a relatively low cost alternative and can be done through two mechanisms: i) improving P use efficiency (PUE), and/or ii) P acquisition efficiency (PAE). PUE is related to the internal allocation/mobilization of P, and is usually represented by the amount of P accumulated per biomass. PAE relies on roots ability to acquire P from the soil, and is commonly expressed as the relative difference of P acquired under low and high P availability conditions. In this review, plant adaptations related to improved PAE are described, with emphasis on arbuscular mycorrhizal (AM) symbiosis, which is generally accepted to enhance plant P acquisition. A state of the art (1980–2018) of AM growth responses and P uptake in wheat and barley is made to discuss about the commonly accepted growth promoting effect and P increased uptake by AM fungi and the contrasting evidence about the generally accepted lack of positive responses in both plant species. Finally, the mechanisms by which AM symbiosis can affect wheat and barley PAE are discussed, highlighting the importance of considering AM functional diversity on future studies and the necessity to improve PAE definition by considering the carbon trading between

Phosphorus Acquisition Efficiency Related to Root Traits: Is Mycorrhizal Symbiosis a Key Factor to Wheat and Barley Cropping?

PubMed

Campos, Pedro; Borie, Fernando; Cornejo, Pablo; López-Ráez, Juan A; López-García, Álvaro; Seguel, Alex

2018-01-01

Wheat ( Triticum aestivum L.) and barley ( Hordeum vulgare L.) are major crops cultivated around the world, thus playing a crucial role on human diet. Remarkably, the growing human population requires a significant increase in agricultural production in order to feed everybody. In this context, phosphorus (P) management is a key factor as it is component of organic molecules such as nucleic acids, ATP and phospholipids, and it is the most abundant macronutrient in biomass after nitrogen (N), although being one of the scarcest elements in the lithosphere. In general, P fertilization has low efficiency, as only a fraction of the applied P is acquired by roots, leaving a substantial amount to be accumulated in soil as not readily available P. Breeding for P-efficient cultivars is a relatively low cost alternative and can be done through two mechanisms: i) improving P use efficiency (PUE), and/or ii) P acquisition efficiency (PAE). PUE is related to the internal allocation/mobilization of P, and is usually represented by the amount of P accumulated per biomass. PAE relies on roots ability to acquire P from the soil, and is commonly expressed as the relative difference of P acquired under low and high P availability conditions. In this review, plant adaptations related to improved PAE are described, with emphasis on arbuscular mycorrhizal (AM) symbiosis, which is generally accepted to enhance plant P acquisition. A state of the art (1980-2018) of AM growth responses and P uptake in wheat and barley is made to discuss about the commonly accepted growth promoting effect and P increased uptake by AM fungi and the contrasting evidence about the generally accepted lack of positive responses in both plant species. Finally, the mechanisms by which AM symbiosis can affect wheat and barley PAE are discussed, highlighting the importance of considering AM functional diversity on future studies and the necessity to improve PAE definition by considering the carbon trading between

Bradyrhizobium-Lupinus mariae-josephae: a unique symbiosis endemic of a basic soil in Eastern Spain

NASA Astrophysics Data System (ADS)

Durán, D.; Sánchez-Cañizares, C.; Navarro, A.; Rey, L.; Imperial, J.; Ruiz-Argüeso, T.

2012-04-01

Lupinus mariae-josephae is an intriguing lupine species recently discovered in the Mediterranean region and constitutes an endemism of a small area of Eastern Spain (Valencia province; Pascual, 2004; Mahé et al. 2011). It opens new perspectives for ecological and agronomic interests, as it represents the sole lupine species that preferentially grows in basic soils, while almost all other lupine species occur in acid to neutral soils. The L. mariae-josephae symbionts isolated from soils of calcareous areas of Valencia are extremely slow-growing bacteria belonging to the Bradyrhrizobium genus and showing symbiotic specificity that prevents nodulation of other Lupinus spp. such as L. angustifolius or L. luteus typically thriving in acid soils (Sanchez-Cañizares et al, 2011). Their phylogenetic analysis based on housekeeping and symbiotic genes showed that L. mariae-josephae symbionts belong to an evolutionary lineage that also includes endosymbiotic bacteria from Retama spp. of Northern Algeria basic soils (Boulila et al. 2009). Conversely, this new lineage is phylogenetically distinct from that of endosymbiotic bacteria from other Lupinus spp. native of the Iberian Peninsula, which were nested mainly within B. canariense and B. japonicum lineages. A genomic diversity study of the indigenous bradyrhizobia population of the calcareous areas in Valencia, based on fingerprint and phylogenetic analysis, showed the existence of a large diversity of genotypes, some of which are related to bacteria from the Retama spp. symbiosis in Algeria. This singular genomic divergence of L. mariae-josephae symbiotic bacteria in such a small geographical area fosters attractive studies on the origin, ecology and evolution of both partners of the symbiosis. Furthermore, it is expected that ongoing seed inoculation experiments with selected strains will allow us to extend the extant distribution spots of L. mariae-josephae plants in Valencia area, and also to determine whether the

Characterization of the cell polarity gene crumbs during the early development and maintenance of the squid-vibrio light organ symbiosis.

PubMed

Peyer, Suzanne M; Heath-Heckman, Elizabeth A C; McFall-Ngai, Margaret J

2017-11-01

The protein Crumbs is a determinant of apical-basal cell polarity and plays a role in apoptosis of epithelial cells and their protection against photodamage. Using the squid-vibrio system, a model for development of symbiotic partnerships, we examined the modulation of the crumbs gene in host epithelial tissues during initiation and maintenance of the association. The extracellular luminous symbiont Vibrio fischeri colonizes the apical surfaces of polarized epithelia in deep crypts of the Euprymna scolopes light organ. During initial colonization each generation, symbiont harvesting is potentiated by the biochemical and biophysical activity of superficial ciliated epithelia, which are several cell layers from the crypt epithelia where the symbionts reside. Within hours of crypt colonization, the symbionts induce the cell death mediated regression of the remote superficial ciliated fields. However, the crypt cells directly interacting with the symbiont are protected from death. In the squid host, we characterized the gene and encoded protein during light organ morphogenesis and in response to symbiosis. Features of the protein sequence and structure, phylogenetic relationships, and localization patterns in the eye supported assignment of the squid protein to the Crumbs family. In situ hybridization revealed that the crumbs transcript shows opposite expression at the onset of symbiosis in the two different regions of the light organ: elevated levels in the superficial epithelia were attenuated whereas low levels in the crypt epithelia were turned up. Although a rhythmic association in which the host controls the symbiont population over the day-night cycle begins in the juvenile upon colonization, cycling of crumbs was evident only in the adult organ with peak expression coincident with maximum symbiont population and luminescence. Our results provide evidence that crumbs responds to symbiont cues that induce developmental apoptosis and to symbiont population

Synthetic biology approaches to engineering the nitrogen symbiosis in cereals.

PubMed

Rogers, Christian; Oldroyd, Giles E D

2014-05-01

Nitrogen is abundant in the earth's atmosphere but, unlike carbon, cannot be directly assimilated by plants. The limitation this places on plant productivity has been circumvented in contemporary agriculture through the production and application of chemical fertilizers. The chemical reduction of nitrogen for this purpose consumes large amounts of energy and the reactive nitrogen released into the environment as a result of fertilizer application leads to greenhouse gas emissions, as well as widespread eutrophication of aquatic ecosystems. The environmental impacts are intensified by injudicious use of fertilizers in many parts of the world. Simultaneously, limitations in the production and supply of chemical fertilizers in other regions are leading to low agricultural productivity and malnutrition. Nitrogen can be directly fixed from the atmosphere by some bacteria and Archaea, which possess the enzyme nitrogenase. Some plant species, most notably legumes, have evolved close symbiotic associations with nitrogen-fixing bacteria. Engineering cereal crops with the capability to fix their own nitrogen could one day address the problems created by the over- and under-use of nitrogen fertilizers in agriculture. This could be achieved either by expression of a functional nitrogenase enzyme in the cells of the cereal crop or through transferring the capability to form a symbiotic association with nitrogen-fixing bacteria. While potentially transformative, these biotechnological approaches are challenging; however, with recent advances in synthetic biology they are viable long-term goals. This review discusses the possibility of these biotechnological solutions to the nitrogen problem, focusing on engineering the nitrogen symbiosis in cereals.

[Formation and function of the bean-rhizobium symbiosis in soy plants upon introduction of strains of Azotobacter and Bacillus species].

PubMed

Mel'nikova, N N; Bulavenko, L V; Kurdish, I K; Titova, L V; Kots', S Ia

2002-01-01

The effects of bacteria belonging to the genera Azotobacter and Bacillus in a mixed culture with Bradyrhizobium japonicum strains on formation and function of the legume-rhizobium symbiosis of soybean plants were studied. The data showed that the bacterial compositions B. japonicum 634b + B. subtilis 5, B. japonicum 634b + A. chroococcum 20, and B. japonicum 10k + A. vinelandii 56 with a cell ratio of 1:0.1 increased the number and weight of root nodules as well as the height and weight of the aboveground plant parts in almost all the cases by 22-105% compared with the control variants. These binary microbial cultures may be used for development of combined bacterial preparations for soybean.

Hemoglobin LjGlb1-1 is involved in nodulation and regulates the level of nitric oxide in the Lotus japonicus-Mesorhizobium loti symbiosis.

PubMed

Fukudome, Mitsutaka; Calvo-Begueria, Laura; Kado, Tomohiro; Osuki, Ken-Ichi; Rubio, Maria Carmen; Murakami, Ei-Ichi; Nagata, Maki; Kucho, Ken-Ichi; Sandal, Niels; Stougaard, Jens; Becana, Manuel; Uchiumi, Toshiki

2016-09-01

Leghemoglobins transport and deliver O2 to the symbiosomes inside legume nodules and are essential for nitrogen fixation. However, the roles of other hemoglobins (Hbs) in the rhizobia-legume symbiosis are unclear. Several Lotus japonicus mutants affecting LjGlb1-1, a non-symbiotic class 1 Hb, have been used to study the function of this protein in symbiosis. Two TILLING alleles with single amino acid substitutions (A102V and E127K) and a LORE1 null allele with a retrotransposon insertion in the 5'-untranslated region (96642) were selected for phenotyping nodulation. Plants of all three mutant lines showed a decrease in long infection threads and nodules, and an increase in incipient infection threads. About 4h after inoculation, the roots of mutant plants exhibited a greater transient accumulation of nitric oxide (NO) than did the wild-type roots; nevertheless, in vitro NO dioxygenase activities of the wild-type, A102V, and E127K proteins were similar, suggesting that the mutated proteins are not fully functional in vivo The expression of LjGlb1-1, but not of the other class 1 Hb of L. japonicus (LjGlb1-2), was affected during infection of wild-type roots, further supporting a specific role for LjGlb1-1. In conclusion, the LjGlb1-1 mutants reveal that this protein is required during rhizobial infection and regulates NO levels. © The Author 2016. Published by Oxford University Press on behalf of the Society for Experimental Biology.

Handling times and saturating transmission functions in a snail-worm symbiosis.

PubMed

Hopkins, Skylar R; McGregor, Cari M; Belden, Lisa K; Wojdak, Jeremy M

2018-06-16

All dynamic species interaction models contain an assumption that describes how contact rates scale with population density. Choosing an appropriate contact-density function is important, because different functions have different implications for population dynamics and stability. However, this choice can be challenging, because there are many possible functions, and most are phenomenological and thus difficult to relate to underlying ecological processes. Using one such phenomenological function, we described a nonlinear relationship between field transmission rates and host density in a common snail-oligochaete symbiosis. We then used a well-known contact function from predator-prey models, the Holling Type II functional response, to describe and predict host snail contact rates in the laboratory. The Holling Type II functional response accurately described both the nonlinear contact-density relationship and the average contact duration that we observed. Therefore, we suggest that contact rates saturate with host density in this system because each snail contact requires a non-instantaneous handling time, and additional possible contacts do not occur during that handling time. Handling times and nonlinear contact rates might also explain the nonlinear relationship between symbiont transmission and snail density that we observed in the field, which could be confirmed by future work that controls for other potential sources of seasonal variation in transmission rates. Because most animal contacts are not instantaneous, the Holling Type II functional response might be broadly relevant to diverse host-symbiont systems.

The Bradyrhizobium japonicum Ferrous Iron Transporter FeoAB Is Required for Ferric Iron Utilization in Free Living Aerobic Cells and for Symbiosis.

PubMed

Sankari, Siva; O'Brian, Mark R

2016-07-22

The bacterium Bradyrhizobium japonicum USDA110 does not synthesize siderophores for iron utilization in aerobic environments, and the mechanism of iron uptake within symbiotic soybean root nodules is unknown. An mbfA bfr double mutant defective in iron export and storage activities cannot grow aerobically in very high iron medium. Here, we found that this phenotype was suppressed by loss of function mutations in the feoAB operon encoding ferrous (Fe(2+)) iron uptake proteins. Expression of the feoAB operon genes was elevated under iron limitation, but mutants defective in either gene were unable to grow aerobically over a wide external ferric (Fe(3+)) iron (FeCl3) concentration range. Thus, FeoAB accommodates iron acquisition under iron limited and iron replete conditions. Incorporation of radiolabel from either (55)Fe(2+) or (59)Fe(3+) into cells was severely defective in the feoA and feoB strains, suggesting Fe(3+) reduction to Fe(2+) prior to traversal across the cytoplasmic membrane by FeoAB. The feoA or feoB deletion strains elicited small, ineffective nodules on soybean roots, containing few bacteria and lacking nitrogen fixation activity. A feoA(E40K) mutant contained partial iron uptake activity in culture that supported normal growth and established an effective symbiosis. The feoA(E40K) strain had partial iron uptake activity in situ within nodules and in isolated cells, indicating that FeoAB is the iron transporter in symbiosis. We conclude that FeoAB supports iron acquisition under limited conditions of soil and in the iron-rich environment of a symbiotic nodule. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

Transcriptomic dissection of Bradyrhizobium sp. strain ORS285 in symbiosis with Aeschynomene spp. inducing different bacteroid morphotypes with contrasted symbiotic efficiency.

PubMed

Lamouche, Florian; Gully, Djamel; Chaumeret, Anaïs; Nouwen, Nico; Verly, Camille; Pierre, Olivier; Sciallano, Coline; Fardoux, Joël; Jeudy, Christian; Szücs, Attila; Mondy, Samuel; Salon, Christophe; Nagy, István; Kereszt, Attila; Dessaux, Yves; Giraud, Eric; Mergaert, Peter; Alunni, Benoit

2018-06-19

To circumvent the paucity of nitrogen sources in the soil legume plants establish a symbiotic interaction with nitrogen-fixing soil bacteria called rhizobia. During symbiosis, the plants form root organs called nodules, where bacteria are housed intracellularly and become active nitrogen fixers known as bacteroids. Depending on their host plant, bacteroids can adopt different morphotypes, being either unmodified (U), elongated (E) or spherical (S). E- and S-type bacteroids undergo a terminal differentiation leading to irreversible morphological changes and DNA endoreduplication. Previous studies suggest that differentiated bacteroids display an increased symbiotic efficiency (E>U and S>U). In this study, we used a combination of Aeschynomene species inducing E- or S-type bacteroids in symbiosis with Bradyrhizobium sp. ORS285 to show that S-type bacteroids present a better symbiotic efficiency than E-type bacteroids. We performed a transcriptomic analysis on E- and S-type bacteroids formed by Aeschynomene afraspera and Aeschynomene indica nodules and identified the bacterial functions activated in bacteroids and specific to each bacteroid type. Extending the expression analysis in E- and S-type bacteroids in other Aeschynomene species by qRT-PCR on selected genes from the transcriptome analysis narrowed down the set of bacteroid morphotype-specific genes. Functional analysis of a selected subset of 31 bacteroid-induced or morphotype-specific genes revealed no symbiotic phenotypes in the mutants. This highlights the robustness of the symbiotic program but could also indicate that the bacterial response to the plant environment is partially anticipatory or even maladaptive. Our analysis confirms the correlation between differentiation and efficiency of the bacteroids and provides a framework for the identification of bacterial functions that affect the efficiency of bacteroids. This article is protected by copyright. All rights reserved. © 2018 Society for Applied

Sinorhizobium meliloti strains TII7 and A5 by Multilocus Sequence Typing (MLST) have chromsomes identical with Rm1021 and form an effective and ineffective symbiosis with Medicago truncatula line Jemalong A17, respectively

USDA-ARS?s Scientific Manuscript database

The strains TII7 and A5 formed an effective and ineffective symbiosis with Medicago truncatula Jemalong A17, respectively. Both were shown to have identical chromsomes with strains Rm1021 and RCR2011 using a Multilocus Sequence Typing method. The 2260 bp segments of DNA stretching from the 3’ end ...

[Iron regulation of gene expression in the Bradyrhizobium japonicum/soybean symbiosis]. Progress report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guerinot, M.L.

We wish to address the question of whether iron plays a regulatory role in the Bradyrhizobium japonicum/soybeam symbiosis. Iron may be an important regulatory signal in planta as the bacteria must acquire iron from their plant hosts and iron-containing proteins figure prominently in all nitrogen-fixing symbioses. For example, the bacterial partner is believed to synthesize the heme moiety of leghemoglobin, which may represent as much as 25--30% of the total soluble protein in an infected plant cell. For this reason, we have focused our attention on the regulation by iron of the first step in the bacterial heme biosynthetic pathway.more » The enzyme which catalyzes this step, 5-aminolevulinic acid synthase, is encoded by the hemA gene which we had previously cloned and sequenced. Specific objectives include: to define the cis-acting sequences which confer iron regulation on the B. japonicum hemA gene; to identify trans-acting factors which regulate the expression of hemA by iron; to identify new loci which are transcriptionally responsive to changes in iron availability; and to examine the effects of mutations in various known regulatory genes for their effect on the expression of hemA.« less

Identification of a gene involved in the regulation of hyphal growth of Epichloë festucae during symbiosis.

PubMed

Bassett, Shalome A; Johnson, Richard D; Simpson, Wayne R; Laugraud, Aurelie; Jordan, T William; Bryan, Gregory T

2016-10-01

Secreted proteins, those involved in cell wall biogenesis, are likely to play a role in communication in the symbiotic interaction between the fungal endophyte Epichloë festucae with perennial ryegrass (Lolium perenne), particularly given the close association between fungal hyphae and the plant cell wall. Our hypothesis was that secreted proteins are likely to be responsible for establishing and maintaining a normal symbiotic relationship. We analyzed an endophyte EST database for genes with predicted signal peptide sequences. Here, we report the identification and characterization of rhgA; a gene involved in the regulation of hyphal growth in planta In planta analysis of ΔrhgA mutants showed that disruption of rhgA resulted in extensive unregulated hyphal growth. This phenotype was fully complemented by insertion of the rhgA gene and suggests that rhgA is important for maintaining normal hyphal growth during symbiosis. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Developmental and microbiological analysis of the inception of bioluminescent symbiosis in the marine fish Nuchequula nuchalis (Perciformes: Leiognathidae).

PubMed

Dunlap, Paul V; Davis, Kimberly M; Tomiyama, Shinichi; Fujino, Misato; Fukui, Atsushi

2008-12-01

Many marine fish harbor luminous bacteria as bioluminescent symbionts. Despite the diversity, abundance, and ecological importance of these fish and their apparent dependence on luminous bacteria for survival and reproduction, little is known about developmental and microbiological events surrounding the inception of their symbioses. To gain insight on these issues, we examined wild-caught larvae of the leiognathid fish Nuchequula nuchalis, a species that harbors Photobacterium leiognathi as its symbiont, for the presence, developmental state, and microbiological status of the fish's internal, supraesophageal light organ. Nascent light organs were evident in the smallest specimens obtained, flexion larvae of 6.0 to 6.5 mm in notochord length (NL), a developmental stage at which the stomach had not yet differentiated and the nascent gasbladder had not established an interface with the light organ. Light organs of certain of the specimens in this size range apparently lacked bacteria, whereas light organs of other specimens of 6.5 mm in NL and of all larger specimens harbored large populations of bacteria, representatives of which were identified as P. leiognathi. Bacteria identified as Vibrio harveyi were also present in the light organ of one larval specimen. Light organ populations were composed typically of two or three genetically distinct strain types of P. leiognathi, similar to the situation in adult fish, and the same strain type was only rarely found in light organs of different larval, juvenile, or adult specimens. Light organs of larvae carried a smaller proportion of strains merodiploid for the lux-rib operon, 79 of 249 strains, than those of adults (75 of 91 strains). These results indicate that light organs of N. nuchalis flexion and postflexion larvae of 6.0 to 6.7 mm in NL are at an early stage of development and that inception of the symbiosis apparently occurs in flexion larvae of 6.0 to 6.5 mm in NL. Ontogeny of the light organ therefore

The lipopolysaccharide core oligosaccharide of Burkholderia plays a critical role in maintaining a proper gut symbiosis with the bean bug Riptortus pedestris.

PubMed

Kim, Jiyeun Kate; Jang, Ho Am; Kim, Min Seon; Cho, Jae Hyun; Lee, Junbeom; Di Lorenzo, Flaviana; Sturiale, Luisa; Silipo, Alba; Molinaro, Antonio; Lee, Bok Luel

2017-11-24

Lipopolysaccharide, the outer cell-wall component of Gram-negative bacteria, has been shown to be important for symbiotic associations. We recently reported that the lipopolysaccharide O-antigen of Burkholderia enhances the initial colonization of the midgut of the bean bug, Riptortus pedestris However, the midgut-colonizing Burkholderia symbionts lack the O-antigen but display the core oligosaccharide on the cell surface. In this study, we investigated the role of the core oligosaccharide, which directly interacts with the host midgut, in the Riptortus-Burkholderia symbiosis. To this end, we generated the core oligosaccharide mutant strains, Δ wabS , Δ wabO , Δ waaF, and Δ waaC, and determined the chemical structures of their oligosaccharides, which exhibited different compositions. The symbiotic properties of these mutant strains were compared with those of the wild-type and O-antigen-deficient Δ wbiG strains. Upon introduction into Riptortus via the oral route, the core oligosaccharide mutant strains exhibited different rates of colonization of the insect midgut. The symbiont titers in fifth-instar insects revealed significantly reduced population sizes of the inner core oligosaccharide mutant strains Δ waaF and Δ waaC These two strains also negatively affected host growth rate and fitness. Furthermore, R. pedestris individuals colonized with the Δ waaF and Δ waaC strains were vulnerable to septic bacterial challenge, similar to insects without a Burkholderia symbiont. Taken together, these results suggest that the core oligosaccharide from Burkholderia symbionts plays a critical role in maintaining a proper symbiont population and in supporting the beneficial effects of the symbiont on its host in the Riptortus-Burkholderia symbiosis. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

Diversity and Spatial Structure of Belowground Plant–Fungal Symbiosis in a Mixed Subtropical Forest of Ectomycorrhizal and Arbuscular Mycorrhizal Plants

PubMed Central

Toju, Hirokazu; Sato, Hirotoshi; Tanabe, Akifumi S.

2014-01-01

Plant–mycorrhizal fungal interactions are ubiquitous in forest ecosystems. While ectomycorrhizal plants and their fungi generally dominate temperate forests, arbuscular mycorrhizal symbiosis is common in the tropics. In subtropical regions, however, ectomycorrhizal and arbuscular mycorrhizal plants co-occur at comparable abundances in single forests, presumably generating complex community structures of root-associated fungi. To reveal root-associated fungal community structure in a mixed forest of ectomycorrhizal and arbuscular mycorrhizal plants, we conducted a massively-parallel pyrosequencing analysis, targeting fungi in the roots of 36 plant species that co-occur in a subtropical forest. In total, 580 fungal operational taxonomic units were detected, of which 132 and 58 were probably ectomycorrhizal and arbuscular mycorrhizal, respectively. As expected, the composition of fungal symbionts differed between fagaceous (ectomycorrhizal) and non-fagaceous (possibly arbuscular mycorrhizal) plants. However, non-fagaceous plants were associated with not only arbuscular mycorrhizal fungi but also several clades of ectomycorrhizal (e.g., Russula) and root-endophytic ascomycete fungi. Many of the ectomycorrhizal and root-endophytic fungi were detected from both fagaceous and non-fagaceous plants in the community. Interestingly, ectomycorrhizal and arbuscular mycorrhizal fungi were concurrently detected from tiny root fragments of non-fagaceous plants. The plant–fungal associations in the forest were spatially structured, and non-fagaceous plant roots hosted ectomycorrhizal fungi more often in the proximity of ectomycorrhizal plant roots. Overall, this study suggests that belowground plant–fungal symbiosis in subtropical forests is complex in that it includes “non-typical” plant–fungal combinations (e.g., ectomycorrhizal fungi on possibly arbuscular mycorrhizal plants) that do not fall within the conventional classification of mycorrhizal symbioses, and in

Arbuscular Mycorrhizal Fungal 14-3-3 Proteins Are Involved in Arbuscule Formation and Responses to Abiotic Stresses During AM Symbiosis

PubMed Central

Sun, Zhongfeng; Song, Jiabin; Xin, Xi’an; Xie, Xianan; Zhao, Bin

2018-01-01

Arbuscular mycorrhizal (AM) fungi are soil-borne fungi belonging to the ancient phylum Glomeromycota and are important symbionts of the arbuscular mycorrhiza, enhancing plant nutrient acquisition and resistance to various abiotic stresses. In contrast to their significant physiological implications, the molecular basis involved is poorly understood, largely due to their obligate biotrophism and complicated genetics. Here, we identify and characterize three genes termed Fm201, Ri14-3-3 and RiBMH2 that encode 14-3-3-like proteins in the AM fungi Funneliformis mosseae and Rhizophagus irregularis, respectively. The transcriptional levels of Fm201, Ri14-3-3 and RiBMH2 are strongly induced in the pre-symbiotic and symbiotic phases, including germinating spores, intraradical hyphae- and arbuscules-enriched roots. To functionally characterize the Fm201, Ri14-3-3 and RiBMH2 genes, we took advantage of a yeast heterologous system owing to the lack of AM fungal transformation systems. Our data suggest that all three genes can restore the lethal Saccharomyces cerevisiae bmh1 bmh2 double mutant on galactose-containing media. Importantly, yeast one-hybrid analysis suggests that the transcription factor RiMsn2 is able to recognize the STRE (CCCCT/AGGGG) element present in the promoter region of Fm201 gene. More importantly, Host-Induced Gene Silencing of both Ri14-3-3 and RiBMH2 in Rhizophagus irregularis impairs the arbuscule formation in AM symbiosis and inhibits the expression of symbiotic PT4 and MST2 genes from plant and fungal partners, respectively. We further subjected the AM fungus-Medicago truncatula association system to drought or salinity stress. Accordingly, the expression profiles in both mycorrhizal roots and extraradical hyphae reveal that these three 14-3-3-like genes are involved in response to drought or salinity stress. Collectively, our results provide new insights into molecular functions of the AM fungal 14-3-3 proteins in abiotic stress responses and

Arbuscular Mycorrhizal Fungal 14-3-3 Proteins Are Involved in Arbuscule Formation and Responses to Abiotic Stresses During AM Symbiosis.

PubMed

Sun, Zhongfeng; Song, Jiabin; Xin, Xi'an; Xie, Xianan; Zhao, Bin

2018-01-01

Arbuscular mycorrhizal (AM) fungi are soil-borne fungi belonging to the ancient phylum Glomeromycota and are important symbionts of the arbuscular mycorrhiza, enhancing plant nutrient acquisition and resistance to various abiotic stresses. In contrast to their significant physiological implications, the molecular basis involved is poorly understood, largely due to their obligate biotrophism and complicated genetics. Here, we identify and characterize three genes termed Fm201 , Ri14-3-3 and RiBMH2 that encode 14-3-3-like proteins in the AM fungi Funneliformis mosseae and Rhizophagus irregularis , respectively. The transcriptional levels of Fm201 , Ri14-3-3 and RiBMH2 are strongly induced in the pre-symbiotic and symbiotic phases, including germinating spores, intraradical hyphae- and arbuscules-enriched roots. To functionally characterize the Fm201 , Ri14-3-3 and RiBMH2 genes, we took advantage of a yeast heterologous system owing to the lack of AM fungal transformation systems. Our data suggest that all three genes can restore the lethal Saccharomyces cerevisiae bmh1 bmh2 double mutant on galactose-containing media. Importantly, yeast one-hybrid analysis suggests that the transcription factor RiMsn2 is able to recognize the STRE (CCCCT/AGGGG) element present in the promoter region of Fm201 gene. More importantly, Host-Induced Gene Silencing of both Ri14-3-3 and RiBMH2 in Rhizophagus irregularis impairs the arbuscule formation in AM symbiosis and inhibits the expression of symbiotic PT4 and MST2 genes from plant and fungal partners, respectively. We further subjected the AM fungus- Medicago truncatula association system to drought or salinity stress. Accordingly, the expression profiles in both mycorrhizal roots and extraradical hyphae reveal that these three 14-3-3-like genes are involved in response to drought or salinity stress. Collectively, our results provide new insights into molecular functions of the AM fungal 14-3-3 proteins in abiotic stress responses and

Diversity and spatial structure of belowground plant-fungal symbiosis in a mixed subtropical forest of ectomycorrhizal and arbuscular mycorrhizal plants.

PubMed

Toju, Hirokazu; Sato, Hirotoshi; Tanabe, Akifumi S

2014-01-01

Plant-mycorrhizal fungal interactions are ubiquitous in forest ecosystems. While ectomycorrhizal plants and their fungi generally dominate temperate forests, arbuscular mycorrhizal symbiosis is common in the tropics. In subtropical regions, however, ectomycorrhizal and arbuscular mycorrhizal plants co-occur at comparable abundances in single forests, presumably generating complex community structures of root-associated fungi. To reveal root-associated fungal community structure in a mixed forest of ectomycorrhizal and arbuscular mycorrhizal plants, we conducted a massively-parallel pyrosequencing analysis, targeting fungi in the roots of 36 plant species that co-occur in a subtropical forest. In total, 580 fungal operational taxonomic units were detected, of which 132 and 58 were probably ectomycorrhizal and arbuscular mycorrhizal, respectively. As expected, the composition of fungal symbionts differed between fagaceous (ectomycorrhizal) and non-fagaceous (possibly arbuscular mycorrhizal) plants. However, non-fagaceous plants were associated with not only arbuscular mycorrhizal fungi but also several clades of ectomycorrhizal (e.g., Russula) and root-endophytic ascomycete fungi. Many of the ectomycorrhizal and root-endophytic fungi were detected from both fagaceous and non-fagaceous plants in the community. Interestingly, ectomycorrhizal and arbuscular mycorrhizal fungi were concurrently detected from tiny root fragments of non-fagaceous plants. The plant-fungal associations in the forest were spatially structured, and non-fagaceous plant roots hosted ectomycorrhizal fungi more often in the proximity of ectomycorrhizal plant roots. Overall, this study suggests that belowground plant-fungal symbiosis in subtropical forests is complex in that it includes "non-typical" plant-fungal combinations (e.g., ectomycorrhizal fungi on possibly arbuscular mycorrhizal plants) that do not fall within the conventional classification of mycorrhizal symbioses, and in that

Evolutionary Dynamics of Nitrogen Fixation in the Legume–Rhizobia Symbiosis

PubMed Central

Fujita, Hironori; Aoki, Seishiro; Kawaguchi, Masayoshi

2014-01-01

The stabilization of host–symbiont mutualism against the emergence of parasitic individuals is pivotal to the evolution of cooperation. One of the most famous symbioses occurs between legumes and their colonizing rhizobia, in which rhizobia extract nutrients (or benefits) from legume plants while supplying them with nitrogen resources produced by nitrogen fixation (or costs). Natural environments, however, are widely populated by ineffective rhizobia that extract benefits without paying costs and thus proliferate more efficiently than nitrogen-fixing cooperators. How and why this mutualism becomes stabilized and evolutionarily persists has been extensively discussed. To better understand the evolutionary dynamics of this symbiosis system, we construct a simple model based on the continuous snowdrift game with multiple interacting players. We investigate the model using adaptive dynamics and numerical simulations. We find that symbiotic evolution depends on the cost–benefit balance, and that cheaters widely emerge when the cost and benefit are similar in strength. In this scenario, the persistence of the symbiotic system is compatible with the presence of cheaters. This result suggests that the symbiotic relationship is robust to the emergence of cheaters, and may explain the prevalence of cheating rhizobia in nature. In addition, various stabilizing mechanisms, such as partner fidelity feedback, partner choice, and host sanction, can reinforce the symbiotic relationship by affecting the fitness of symbionts in various ways. This result suggests that the symbiotic relationship is cooperatively stabilized by various mechanisms. In addition, mixed nodule populations are thought to encourage cheater emergence, but our model predicts that, in certain situations, cheaters can disappear from such populations. These findings provide a theoretical basis of the evolutionary dynamics of legume–rhizobia symbioses, which is extendable to other single-host, multiple

Arbuscular mycorrhizal symbiosis influences arsenic accumulation and speciation in Medicago truncatula L. in arsenic-contaminated soil.

PubMed

Zhang, Xin; Ren, Bai-Hui; Wu, Song-Lin; Sun, Yu-Qing; Lin, Ge; Chen, Bao-Dong

2015-01-01

In two pot experiments, wild type and a non-mycorrhizal mutant (TR25:3-1) of Medicago truncatula were grown in arsenic (As)-contaminated soil to investigate the influences of arbuscular mycorrhizal fungi (AMF) on As accumulation and speciation in host plants. The results indicated that the plant biomass of M. truncatula was dramatically increased by AM symbiosis. Mycorrhizal colonization significantly increased phosphorus concentrations and decreased As concentrations in plants. Moreover, mycorrhizal colonization generally increased the percentage of arsenite in total As both in shoots and roots, while dimethylarsenic acid (DMA) was only detected in shoots of mycorrhizal plants. The results suggested that AMF are most likely to get involved in the methylating of inorganic As into less toxic organic DMA and also in the reduction of arsenate to arsenite. The study allowed a deeper insight into the As detoxification mechanisms in AM associations. By using the mutant M. truncatula, we demonstrated the importance of AMF in plant As tolerance under natural conditions. Copyright © 2014 Elsevier Ltd. All rights reserved.

Differential Sharing of Chemical Cues by Social Parasites Versus Social Mutualists in a Three-Species Symbiosis.

PubMed

Emery, Virginia J; Tsutsui, Neil D

2016-04-01

Chemical recognition systems are crucial for maintaining the unity of social insect colonies. It has been proposed that colonies form a common chemical signature, called the gestalt odor, which is used to distinguish colony members and non-members. This chemical integration is achieved actively through social interactions such as trophallaxis and allogrooming, or passively such as through exposure to common nest material. When colonies are infiltrated by social parasites, the intruders often use some form of chemical mimicry. However, it is not always clear how this chemical mimicry is accomplished. Here, we used a three-species nesting symbiosis to test the differences in chemical integration of mutualistic (parabiotic) and parasitic ant species. We found that the parasite (Solenopsis picea) obtains chemical cues from both of the two parabiotic host ant species. However, the two parabiotic species (Crematogaster levior and Camponotus femoratus) maintain species-specific cues, and do not acquire compounds from the other species. Our findings suggest that there is a fundamental difference in how social mutualists and social parasites use chemicals to integrate themselves into colonies.

Host-selected mutations converging on a global regulator drive an adaptive leap towards symbiosis in bacteria

PubMed Central

Sabrina Pankey, M; Foxall, Randi L; Ster, Ian M; Perry, Lauren A; Schuster, Brian M; Donner, Rachel A; Coyle, Matthew; Cooper, Vaughn S; Whistler, Cheryl A

2017-01-01

Host immune and physical barriers protect against pathogens but also impede the establishment of essential symbiotic partnerships. To reveal mechanisms by which beneficial organisms adapt to circumvent host defenses, we experimentally evolved ecologically distinct bioluminescent Vibrio fischeri by colonization and growth within the light organs of the squid Euprymna scolopes. Serial squid passaging of bacteria produced eight distinct mutations in the binK sensor kinase gene, which conferred an exceptional selective advantage that could be demonstrated through both empirical and theoretical analysis. Squid-adaptive binK alleles promoted colonization and immune evasion that were mediated by cell-associated matrices including symbiotic polysaccharide (Syp) and cellulose. binK variation also altered quorum sensing, raising the threshold for luminescence induction. Preexisting coordinated regulation of symbiosis traits by BinK presented an efficient solution where altered BinK function was the key to unlock multiple colonization barriers. These results identify a genetic basis for microbial adaptability and underscore the importance of hosts as selective agents that shape emergent symbiont populations. DOI: http://dx.doi.org/10.7554/eLife.24414.001 PMID:28447935

Activation of Symbiosis Signaling by Arbuscular Mycorrhizal Fungi in Legumes and Rice[OPEN

PubMed Central

Sun, Jongho; Miller, J. Benjamin; Granqvist, Emma; Wiley-Kalil, Audrey; Gobbato, Enrico; Maillet, Fabienne; Cottaz, Sylvain; Samain, Eric; Venkateshwaran, Muthusubramanian; Fort, Sébastien; Morris, Richard J.; Ané, Jean-Michel; Dénarié, Jean; Oldroyd, Giles E.D.

2015-01-01

Establishment of arbuscular mycorrhizal interactions involves plant recognition of diffusible signals from the fungus, including lipochitooligosaccharides (LCOs) and chitooligosaccharides (COs). Nitrogen-fixing rhizobial bacteria that associate with leguminous plants also signal to their hosts via LCOs, the so-called Nod factors. Here, we have assessed the induction of symbiotic signaling by the arbuscular mycorrhizal (Myc) fungal-produced LCOs and COs in legumes and rice (Oryza sativa). We show that Myc-LCOs and tetra-acetyl chitotetraose (CO4) activate the common symbiosis signaling pathway, with resultant calcium oscillations in root epidermal cells of Medicago truncatula and Lotus japonicus. The nature of the calcium oscillations is similar for LCOs produced by rhizobial bacteria and by mycorrhizal fungi; however, Myc-LCOs activate distinct gene expression. Calcium oscillations were activated in rice atrichoblasts by CO4, but not the Myc-LCOs, whereas a mix of CO4 and Myc-LCOs activated calcium oscillations in rice trichoblasts. In contrast, stimulation of lateral root emergence occurred following treatment with Myc-LCOs, but not CO4, in M. truncatula, whereas both Myc-LCOs and CO4 were active in rice. Our work indicates that legumes and non-legumes differ in their perception of Myc-LCO and CO signals, suggesting that different plant species respond to different components in the mix of signals produced by arbuscular mycorrhizal fungi. PMID:25724637

Altered Carbohydrates Allocation by Associated Bacteria-fungi Interactions in a Bark Beetle-microbe Symbiosis

PubMed Central

Zhou, Fangyuan; Lou, Qiaozhe; Wang, Bo; Xu, Letian; Cheng, Chihang; Lu, Min; Sun, Jianghua

2016-01-01

Insect-microbe interaction is a key area of research in multiplayer symbiosis, yet little is known about the role of microbe-microbe interactions in insect-microbe symbioses. The red turpentine beetle (RTB) has destroyed millions of healthy pines in China and forms context-dependent relationships with associated fungi. The adult-associated fungus Leptographium procerum have played key roles in RTB colonization. However, common fungal associates (L. procerum and Ophiostoma minus) with RTB larvae compete for carbohydrates. Here, we report that dominant bacteria associated with RTB larvae buffer the competition by inhibiting the growth and D-glucose consumption of O. minus. However, they didn’t inhibit the growth of L. procerum and forced this fungus to consume D-pinitol before consuming D-glucose, even though D-glucose was available and a better carbon source not only for L. procerum but also for RTB larvae and associated bacteria. This suggests the most frequently isolated bacteria associated with RTB larvae could affect fungal growth and the sequence of carbohydrate consumption. Thus, this regulates carbohydrate allocation in the RTB larva-microbe community, which may in turn benefit RTB larvae development. We also discuss the mechanism of carbohydrate allocation in the RTB larva-microbe community, and its potential contribution to the maintenance of a symbiotic community. PMID:26839264

Rhizobium-Legume Symbiosis and Nitrogen Fixation under Severe Conditions and in an Arid Climate

PubMed Central

Zahran, Hamdi Hussein

1999-01-01

Biological N2 fixation represents the major source of N input in agricultural soils including those in arid regions. The major N2-fixing systems are the symbiotic systems, which can play a significant role in improving the fertility and productivity of low-N soils. The Rhizobium-legume symbioses have received most attention and have been examined extensively. The behavior of some N2-fixing systems under severe environmental conditions such as salt stress, drought stress, acidity, alkalinity, nutrient deficiency, fertilizers, heavy metals, and pesticides is reviewed. These major stress factors suppress the growth and symbiotic characteristics of most rhizobia; however, several strains, distributed among various species of rhizobia, are tolerant to stress effects. Some strains of rhizobia form effective (N2-fixing) symbioses with their host legumes under salt, heat, and acid stresses, and can sometimes do so under the effect of heavy metals. Reclamation and improvement of the fertility of arid lands by application of organic (manure and sewage sludge) and inorganic (synthetic) fertilizers are expensive and can be a source of pollution. The Rhizobium-legume (herb or tree) symbiosis is suggested to be the ideal solution to the improvement of soil fertility and the rehabilitation of arid lands and is an important direction for future research. PMID:10585971

Cellular responses in the cyanobacterial symbiont during its vertical transfer between plant generations in the Azolla microphylla symbiosis.

PubMed

Zheng, Weiwen; Bergman, Birgitta; Chen, Bin; Zheng, Siping; Guan, Xiong; Xiang, Guan; Rasmussen, Ulla

2009-01-01

The nitrogen-fixing symbiosis between cyanobacteria and the water fern Azolla microphylla is, in contrast to other cyanobacteria-plant symbioses, the only one of a perpetual nature. The cyanobacterium is vertically transmitted between the plant generations, via vegetative fragmentation of the host or sexually within megasporocarps. In the latter process, subsets of the cyanobacterial population living endophytically in the Azolla leaves function as inocula for the new plant generations. Using electron microscopy and immunogold-labeling, the fate of the cyanobacterium during colonization and development of the megasporocarp was revealed. On entering the indusium chamber of the megasporocarps as small-celled motile cyanobacterial filaments (hormogonia), these differentiated into large thick-walled akinetes (spores) in a synchronized manner. This process was accompanied by cytoplasmic reorganizations and the release of numerous membrane vesicles, most of which contained DNA, and the formation of a highly structured biofilm. Taken together the data revealed complex adaptations in the cyanobacterium during its transition between plant generations.

Developmental and Microbiological Analysis of the Inception of Bioluminescent Symbiosis in the Marine Fish Nuchequula nuchalis (Perciformes: Leiognathidae)▿

PubMed Central

Dunlap, Paul V.; Davis, Kimberly M.; Tomiyama, Shinichi; Fujino, Misato; Fukui, Atsushi

2008-01-01

Many marine fish harbor luminous bacteria as bioluminescent symbionts. Despite the diversity, abundance, and ecological importance of these fish and their apparent dependence on luminous bacteria for survival and reproduction, little is known about developmental and microbiological events surrounding the inception of their symbioses. To gain insight on these issues, we examined wild-caught larvae of the leiognathid fish Nuchequula nuchalis, a species that harbors Photobacterium leiognathi as its symbiont, for the presence, developmental state, and microbiological status of the fish's internal, supraesophageal light organ. Nascent light organs were evident in the smallest specimens obtained, flexion larvae of 6.0 to 6.5 mm in notochord length (NL), a developmental stage at which the stomach had not yet differentiated and the nascent gasbladder had not established an interface with the light organ. Light organs of certain of the specimens in this size range apparently lacked bacteria, whereas light organs of other specimens of 6.5 mm in NL and of all larger specimens harbored large populations of bacteria, representatives of which were identified as P. leiognathi. Bacteria identified as Vibrio harveyi were also present in the light organ of one larval specimen. Light organ populations were composed typically of two or three genetically distinct strain types of P. leiognathi, similar to the situation in adult fish, and the same strain type was only rarely found in light organs of different larval, juvenile, or adult specimens. Light organs of larvae carried a smaller proportion of strains merodiploid for the lux-rib operon, 79 of 249 strains, than those of adults (75 of 91 strains). These results indicate that light organs of N. nuchalis flexion and postflexion larvae of 6.0 to 6.7 mm in NL are at an early stage of development and that inception of the symbiosis apparently occurs in flexion larvae of 6.0 to 6.5 mm in NL. Ontogeny of the light organ therefore

Common mycorrhizal networks and their effect on the bargaining power of the fungal partner in the arbuscular mycorrhizal symbiosis.

PubMed

Bücking, Heike; Mensah, Jerry A; Fellbaum, Carl R

2016-01-01

Arbuscular mycorrhizal (AM) fungi form mutualistic interactions with the majority of land plants, including some of the most important crop species. The fungus takes up nutrients from the soil, and transfers these nutrients to the mycorrhizal interface in the root, where these nutrients are exchanged against carbon from the host. AM fungi form extensive hyphal networks in the soil and connect with their network multiple host plants. These common mycorrhizal networks (CMNs) play a critical role in the long-distance transport of nutrients through soil ecosystems and allow the exchange of signals between the interconnected plants. CMNs affect the survival, fitness, and competitiveness of the fungal and plant species that interact via these networks, but how the resource transport within these CMNs is controlled is largely unknown. We discuss the significance of CMNs for plant communities and for the bargaining power of the fungal partner in the AM symbiosis.

Comparative Genomics Reveals the Core Gene Toolbox for the Fungus-Insect Symbiosis

PubMed Central

Stata, Matt; Wang, Wei; White, Merlin M.; Moncalvo, Jean-Marc

2018-01-01

ABSTRACT Modern genomics has shed light on many entomopathogenic fungi and expanded our knowledge widely; however, little is known about the genomic features of the insect-commensal fungi. Harpellales are obligate commensals living in the digestive tracts of disease-bearing insects (black flies, midges, and mosquitoes). In this study, we produced and annotated whole-genome sequences of nine Harpellales taxa and conducted the first comparative analyses to infer the genomic diversity within the members of the Harpellales. The genomes of the insect gut fungi feature low (26% to 37%) GC content and large genome size variations (25 to 102 Mb). Further comparisons with insect-pathogenic fungi (from both Ascomycota and Zoopagomycota), as well as with free-living relatives (as negative controls), helped to identify a gene toolbox that is essential to the fungus-insect symbiosis. The results not only narrow the genomic scope of fungus-insect interactions from several thousands to eight core players but also distinguish host invasion strategies employed by insect pathogens and commensals. The genomic content suggests that insect commensal fungi rely mostly on adhesion protein anchors that target digestive system, while entomopathogenic fungi have higher numbers of transmembrane helices, signal peptides, and pathogen-host interaction (PHI) genes across the whole genome and enrich genes as well as functional domains to inactivate the host inflammation system and suppress the host defense. Phylogenomic analyses have revealed that genome sizes of Harpellales fungi vary among lineages with an integer-multiple pattern, which implies that ancient genome duplications may have occurred within the gut of insects. PMID:29764946

Evidence that glucose is the major transferred metabolite in dinoflagellate-cnidarian symbiosis.

PubMed

Burriesci, Matthew S; Raab, Theodore K; Pringle, John R

2012-10-01

Reef-building corals and many other cnidarians are symbiotic with dinoflagellates of the genus Symbiodinium. It has long been known that the endosymbiotic algae transfer much of their photosynthetically fixed carbon to the host and that this can provide much of the host's total energy. However, it has remained unclear which metabolite(s) are directly translocated from the algae into the host tissue. We reexamined this question in the small sea anemone Aiptasia using labeling of intact animals in the light with (13)C-bicarbonate, rapid homogenization and separation of animal and algal fractions, and analysis of metabolite labeling by gas chromatography-mass spectrometry. We found labeled glucose in the animal fraction within 2 min of exposure to (13)C-bicarbonate, whereas no significant labeling of other compounds was observed within the first 10 min. Although considerable previous evidence has suggested that glycerol might be a major translocated metabolite, we saw no significant labeling of glycerol within the first hour, and incubation of intact animals with (13)C-labeled glycerol did not result in a rapid production of (13)C-glucose. In contrast, when Symbiodinium cells freshly isolated from host tissue were exposed to light and (13)C-bicarbonate in the presence of host homogenate, labeled glycerol, but not glucose, was detected in the medium. We also observed early production of labeled glucose, but not glycerol, in three coral species. Taken together, the results suggest that glucose is the major translocated metabolite in dinoflagellate-cnidarian symbiosis and that the release of glycerol from isolated algae may be part of a stress response.

Photo- and heterotrophic nitrogenase activity by the cyano-bacterium Nostoc in symbiosis with the bryophyte Anthoceros

DOE Office of Scientific and Technical Information (OSTI.GOV)

Steinberg, N.A.; Meeks, J.C.

1987-04-01

In symbiosis with Anthoceros, Nostoc is thought to do little or no photosynthesis. However, light-dependent /sup 14/CO/sub 2/ fixation by symbiotic Nostoc, freshly isolated from pure cultures of the reconstituted Anthoceros-Nostoc association, was 16% of that by free-living Nostoc. A DCMU-resistant mutant of Nostoc was isolated that fixed CO/sub 2/ at rates comparable to wild-type in both symbiotic and free-living growth states. To determine if symbiotic Nostoc can use its photosynthate directly to fix nitrogen, acetylene reduction by Anthoceros associations reconstituted with wild-type Nostoc was compared to associations with the DCMU-resistant mutant. In wild-type Anthoceros-Nostoc acetylene reduction was inhibited 97%more » by 5 ..mu..M DCMU, while inhibition of the DCMU-resistant Nostoc association was only 63%. Additions of glucose, fructose, maltose or sucrose to wild-type associations completely restored DCMU-inhibited acetylene reduction in the light. Acetylene reduction in the dark was stimulated by glucose, attaining 84% of the uninhibited light-dependent value. The authors conclude that symbiotic Nostoc maintains a pool of photosynthate which supports nitrogenase activity. The pool can also be supplemented from plant sources.« less

The dual nature of haemocyanin in the establishment and persistence of the squid–vibrio symbiosis

PubMed Central

Kremer, Natacha; Schwartzman, Julia; Augustin, René; Zhou, Lawrence; Ruby, Edward G.; Hourdez, Stéphane; McFall-Ngai, Margaret J.

2014-01-01

We identified and sequenced from the squid Euprymna scolopes two isoforms of haemocyanin that share the common structural/physiological characteristics of haemocyanin from a closely related cephalopod, Sepia officinalis, including a pronounced Bohr effect. We examined the potential roles for haemocyanin in the animal's symbiosis with the luminous bacterium Vibrio fischeri. Our data demonstrate that, as in other cephalopods, the haemocyanin is primarily synthesized in the gills. It transits through the general circulation into other tissues and is exported into crypt spaces that support the bacterial partner, which requires oxygen for its bioluminescence. We showed that the gradient of pH between the circulating haemolymph and the matrix of the crypt spaces in adult squid favours offloading of oxygen from the haemocyanin to the symbionts. Haemocyanin is also localized to the apical surfaces and associated mucus of a juvenile-specific epithelium on which the symbionts gather, and where their specificity is determined during the recruitment into the association. The haemocyanin has an antimicrobial activity, which may be involved in this enrichment of V. fischeri during symbiont initiation. Taken together, these data provide evidence that the haemocyanin plays a role in shaping two stages of the squid–vibrio partnership. PMID:24807261

The role of mycorrhizal symbiosis in aluminum and phosphorus interactions in relation to aluminum tolerance in soybean.

PubMed

Zhang, Shuang; Zhou, Jia; Wang, Guihua; Wang, Xiurong; Liao, Hong

2015-12-01

Arbuscular mycorrhizal (AM) fungi protect plants against aluminum (Al) toxicity, but the mechanisms of Al and phosphorus (P) interactions in relation to Al tolerance in mycorrhizal plants are only poorly understood. In this study, varying Al and P treatments were applied to soybean plants cultivated in the presence or absence of three different AM fungi. The results showed that plants in symbiotic association with Gigaspora margarita displayed higher Al tolerance than Rhizophagus irregularis or Glomus claroideum. The effectiveness of G. margarita appeared to be associated with more abundant arbuscules and less affected intraradical hyphae compared to no Al controls. The highest levels of Al toxicity mitigation were observed with the combination of high P availability and AM fungal inoculation, which was associated with a concomitant increase in the expression of the AM-inducible phosphate (Pi) transporter gene GmPT9 in soybean. Taken together, these results suggest that AM symbiosis can alleviate Al toxicity in soybean through enhanced P nutrition, as well as, the alteration of the abundance of mycorrhizal infection structures. These findings highlight the importance of P nutrition status in ameliorating Al toxicity in mycorrhizal plants.

Practical Application of Methanol-Mediated Mutualistic Symbiosis between Methylobacterium Species and a Roof Greening Moss, Racomitrium japonicum

PubMed Central

Tani, Akio; Takai, Yuichiro; Suzukawa, Ikko; Akita, Motomu; Murase, Haruhiko; Kimbara, Kazuhide

2012-01-01

Bryophytes, or mosses, are considered the most maintenance-free materials for roof greening. Racomitrium species are most often used due to their high tolerance to desiccation. Because they grow slowly, a technology for forcing their growth is desired. We succeeded in the efficient production of R. japonicum in liquid culture. The structure of the microbial community is crucial to stabilize the culture. A culture-independent technique revealed that the cultures contain methylotrophic bacteria. Using yeast cells that fluoresce in the presence of methanol, methanol emission from the moss was confirmed, suggesting that it is an important carbon and energy source for the bacteria. We isolated Methylobacterium species from the liquid culture and studied their characteristics. The isolates were able to strongly promote the growth of some mosses including R. japonicum and seed plants, but the plant-microbe combination was important, since growth promotion was not uniform across species. One of the isolates, strain 22A, was cultivated with R. japonicum in liquid culture and in a field experiment, resulting in strong growth promotion. Mutualistic symbiosis can thus be utilized for industrial moss production. PMID:22479445

Symbiosis of Arbuscular Mycorrhizal Fungi and Robinia pseudoacacia L. Improves Root Tensile Strength and Soil Aggregate Stability.

PubMed

Zhang, Haoqiang; Liu, Zhenkun; Chen, Hui; Tang, Ming

2016-01-01

Robinia pseudoacacia L. (black locust) is a widely planted tree species on Loess Plateau for revegetation. Due to its symbiosis forming capability with arbuscular mycorrhizal (AM) fungi, we explored the influence of arbuscular mycorrhizal fungi on plant biomass, root morphology, root tensile strength and soil aggregate stability in a pot experiment. We inoculated R. pseudoacacia with/without AM fungus (Rhizophagus irregularis or Glomus versiforme), and measured root colonization, plant growth, root morphological characters, root tensile force and tensile strength, and parameters for soil aggregate stability at twelve weeks after inoculation. AM fungi colonized more than 70% plant root, significantly improved plant growth. Meanwhile, AM fungi elevated root morphological parameters, root tensile force, root tensile strength, Glomalin-related soil protein (GRSP) content in soil, and parameters for soil aggregate stability such as water stable aggregate (WSA), mean weight diameter (MWD) and geometric mean diameter (GMD). Root length was highly correlated with WSA, MWD and GMD, while hyphae length was highly correlated with GRSP content. The improved R. pseudoacacia growth, root tensile strength and soil aggregate stability indicated that AM fungi could accelerate soil fixation and stabilization with R. pseudoacacia, and its function in revegetation on Loess Plateau deserves more attention.

Use of Hybridization Chain Reaction-Fluorescent In Situ Hybridization To Track Gene Expression by Both Partners during Initiation of Symbiosis.

PubMed

Nikolakakis, K; Lehnert, E; McFall-Ngai, M J; Ruby, E G

2015-07-01

The establishment of a productive symbiosis between Euprymna scolopes, the Hawaiian bobtail squid, and its luminous bacterial symbiont, Vibrio fischeri, is mediated by transcriptional changes in both partners. A key challenge to unraveling the steps required to successfully initiate this and many other symbiotic associations is characterization of the timing and location of these changes. We report on the adaptation of hybridization chain reaction-fluorescent in situ hybridization (HCR-FISH) to simultaneously probe the spatiotemporal regulation of targeted genes in both E. scolopes and V. fischeri. This method revealed localized, transcriptionally coregulated epithelial cells within the light organ that responded directly to the presence of bacterial cells while, at the same time, provided a sensitive means to directly show regulated gene expression within the symbiont population. Thus, HCR-FISH provides a new approach for characterizing habitat transition in bacteria and for discovering host tissue responses to colonization. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Disaster management as part of curriculum for undergraduate and postgraduate courses: The Symbiosis model

PubMed Central

Deshpande, Vijay

2011-01-01

From times immemorial disasters in some form or the other have been regularly visiting humankind and humans have been trying to manage these upheavals. Noah's arch is the first such endeavor. The United Nations declared 1990-1999 as International Decade for Disaster Reduction. The Indian Government passed the Disaster Management Act 2005. As a consequence of the Act, the National Disaster Management Authority was setup. All states were given the guide lines for disaster risk reduction. The objective of this article is to get a clearer picture of what various states, educational authorities and international bodies have done and what Symbiosis International University (SIU) has done so far. Inputs from various States of the Indian Union and neighboring countries were studied. The moot question that figured all the time was “Is there a conscious effort to include Disaster Management in the curricula of various courses at the college and university level” and what are the achievements. It was seen that the Central Board for Secondary Education with support from the Ministry of Home Affairs, Ministry of Human Resource Development and United Nations Development Project have incorporated DM, as part of its frontline curriculum. Most of the Universities in the disaster prone states have enunciated policies for including DM in the curriculum, but palpable results are still awaited. In the SIU, DM has been incorporated in the curriculum and is mandatory for all undergraduate and postgraduate courses. PMID:22412285

Disaster management as part of curriculum for undergraduate and postgraduate courses: The Symbiosis model.

PubMed

Deshpande, Vijay

2011-09-01

From times immemorial disasters in some form or the other have been regularly visiting humankind and humans have been trying to manage these upheavals. Noah's arch is the first such endeavor. The United Nations declared 1990-1999 as International Decade for Disaster Reduction. The Indian Government passed the Disaster Management Act 2005. As a consequence of the Act, the National Disaster Management Authority was setup. All states were given the guide lines for disaster risk reduction. The objective of this article is to get a clearer picture of what various states, educational authorities and international bodies have done and what Symbiosis International University (SIU) has done so far. Inputs from various States of the Indian Union and neighboring countries were studied. The moot question that figured all the time was "Is there a conscious effort to include Disaster Management in the curricula of various courses at the college and university level" and what are the achievements. It was seen that the Central Board for Secondary Education with support from the Ministry of Home Affairs, Ministry of Human Resource Development and United Nations Development Project have incorporated DM, as part of its frontline curriculum. Most of the Universities in the disaster prone states have enunciated policies for including DM in the curriculum, but palpable results are still awaited. In the SIU, DM has been incorporated in the curriculum and is mandatory for all undergraduate and postgraduate courses.

Split-root systems applied to the study of the legume-rhizobial symbiosis: what have we learned?

PubMed

Larrainzar, Estíbaliz; Gil-Quintana, Erena; Arrese-Igor, Cesar; González, Esther M; Marino, Daniel

2014-12-01

Split-root system (SRS) approaches allow the differential treatment of separate and independent root systems, while sharing a common aerial part. As such, SRS is a useful tool for the discrimination of systemic (shoot origin) versus local (root/nodule origin) regulation mechanisms. This type of approach is particularly useful when studying the complex regulatory mechanisms governing the symbiosis established between legumes and Rhizobium bacteria. The current work provides an overview of the main insights gained from the application of SRS approaches to understand how nodule number (nodulation autoregulation) and nitrogen fixation are controlled both under non-stressful conditions and in response to a variety of stresses. Nodule number appears to be mainly controlled at the systemic level through a signal which is produced by nodule/root tissue, translocated to the shoot, and transmitted back to the root system, involving shoot Leu-rich repeat receptor-like kinases. In contrast, both local and systemic mechanisms have been shown to operate for the regulation of nitrogenase activity in nodules. Under drought and heavy metal stress, the regulation is mostly local, whereas the application of exogenous nitrogen seems to exert a regulation of nitrogen fixation both at the local and systemic levels. © 2014 Institute of Botany, Chinese Academy of Sciences.

Effect of chlorimuron-ethyl on Bradyrhizobium japonicum and its symbiosis with soybean.

PubMed

Zawoznik, Myriam S; Tomaro, María L

2005-10-01

Possible side-effects of the acetolactate synthase (ALS)-inhibiting herbicide chlorimuron-ethyl on Bradyrhizobium japonicum (Kirchner & Jordan) in pure culture and on inoculated soybean plants growing under controlled conditions were investigated. Growth of B japonicum strain E109 was not affected by this herbicide even when exposed to concentrations 150 times higher than recommended field doses. However, nodulation of soybean plants treated 5 days after emergence with chlorimuron-ethyl at standard application rates was impaired: a 38% decrease in the number of nodules per plant was observed four weeks after treatment. Despite nodule number decrease, no changes in shoot nitrogen content could be detected. Total fresh biomass was diminished by 25% in herbicide-treated plants. Leghemoglobin content in nodules did not vary; nevertheless total nodule protein was diminished by 40% in the herbicide-treated group. ALS activity in different soybean tissues and their relative sensitivity to chlorimuron-ethyl were also investigated. Roots and bacteroids had the greatest specific ALS activities. On a fresh weight basis, the bacteroid fraction displayed the highest ALS activity and was also the most tolerant to in vitro chlorimuron addition: 72% of its activity was retained after including 10 microM chlorimuron-ethyl in the reaction mixture. These results indicate that standard application rates of chlorimuron-ethyl will have limited incidence on B japonicum survival, and effects on nodulation may have little long-term consequences on soybean nitrogen fixation potential. The differences found among soybean tissues not only in intrinsic ALS activity but also in their relative sensitivity to this herbicide suggests that, in leguminous plants living in symbiosis with rhizobia, nodules may contribute to an enhanced tolerance to ALS inhibitors. Copyright (c) 2005 Society of Chemical Industry.

How does an animal behave like a plant? Physiological and molecular adaptations of zooxanthellae and their hosts to symbiosis.

PubMed

Allemand, Denis; Furla, Paola

2018-04-09

Cnidarians (corals and sea anemones) harbouring photosynthetic microalgae derive several benefits from their association. To allow this association, numerous symbiotic-dependent adaptations in both partners, resulting from evolutionary pressures, have been selected. The dinoflagellate symbionts (zooxanthellae) are located inside a vesicle in the cnidarian host cell and are therefore exposed to a very different environment compared to the free-living state of these microalgae in terms of ion concentration and carbon content and speciation. In addition, this intracellular localization imposes that they rely completely upon the host for their nutrient supply (nitrogen, CO 2 ). Symbiotic-dependent adaptations imposed to the animal host by phototrophic symbiosis are more relevant to photosynthetic organisms than to metazoans: indeed, the cnidarian host often harbours diurnal changes of morphology to adapt itself to the amount of light and possesses carbon-concentrating mechanisms, antioxidative defences and UV sunscreens similar to that present in phototrophs. These adaptations and the contrasting fragility of the association are discussed from both ecological and evolutionary points of view. Copyright © 2018 Académie des sciences. Published by Elsevier Masson SAS. All rights reserved.

From pollen tubes to infection threads: recruitment of Medicago floral pectic genes for symbiosis.

PubMed

Rodríguez-Llorente, Ignacio D; Pérez-Hormaeche, Javier; El Mounadi, Kaoutar; Dary, Mohammed; Caviedes, Miguel A; Cosson, Viviane; Kondorosi, Adam; Ratet, Pascal; Palomares, Antonio J

2004-08-01

While the biology of nitrogen-fixing root nodules has been extensively studied, little is known about the evolutionary events that predisposed legume plants to form symbiosis with rhizobia. We have studied the presence and the expression of two pectic gene families in Medicago, polygalacturonases (PGs) and pectin methyl esterases (PMEs) during the early steps of the Sinorhizobium meliloti-Medicago interaction and compared them with related pollen-specific genes. First, we have compared the expression of MsPG3, a PG gene specifically expressed during the symbiotic interaction, with the expression of MsPG11, a highly homologous pollen-specific gene, using promoter-gus fusions in transgenic M. truncatula and tobacco plants. These results demonstrated that the symbiotic promoter functions as a pollen-specific promoter in the non-legume host. Second, we have identified the presence of a gene family of at least eight differentially expressed PMEs in Medicago. One subfamily is represented by one symbiotic gene (MtPER) and two pollen-expressed genes (MtPEF1 and MtPEF2) that are clustered in the M. truncatula genome. The promoter-gus studies presented in this work and the homology between plant PGs, together with the analysis of the PME locus structure and MtPER expression studies, suggest that the symbiotic MsPG3 and MtPER could have as ancestors pollen-expressed genes involved in polar tip growth processes during pollen tube elongation. Moreover, they could have been recruited after gene duplication in the symbiotic interaction to facilitate polar tip growth during infection thread formation.

Bacterial bioluminescence regulates expression of a host cryptochrome gene in the squid-Vibrio symbiosis.

PubMed

Heath-Heckman, Elizabeth A C; Peyer, Suzanne M; Whistler, Cheryl A; Apicella, Michael A; Goldman, William E; McFall-Ngai, Margaret J

2013-04-02

The symbiosis between the squid Euprymna scolopes and its luminous symbiont, Vibrio fischeri, is characterized by daily transcriptional rhythms in both partners and daily fluctuations in symbiont luminescence. In this study, we sought to determine whether symbionts affect host transcriptional rhythms. We identified two transcripts in host tissues (E. scolopes cry1 [escry1] and escry2) that encode cryptochromes, proteins that influence circadian rhythms in other systems. Both genes cycled daily in the head of the squid, with a pattern similar to that of other animals, in which expression of certain cry genes is entrained by environmental light. In contrast, escry1 expression cycled in the symbiont-colonized light organ with 8-fold upregulation coincident with the rhythms of bacterial luminescence, which are offset from the day/night light regime. Colonization of the juvenile light organ by symbionts was required for induction of escry1 cycling. Further, analysis with a mutant strain defective in light production showed that symbiont luminescence is essential for cycling of escry1; this defect could be complemented by presentation of exogenous blue light. However, blue-light exposure alone did not induce cycling in nonsymbiotic animals, but addition of molecules of the symbiont cell envelope to light-exposed animals did recover significant cycling activity, showing that light acts in synergy with other symbiont features to induce cycling. While symbiont luminescence may be a character specific to rhythms of the squid-vibrio association, resident microbial partners could similarly influence well-documented daily rhythms in other systems, such as the mammalian gut.

Searching for a Toxic Key to Unlock the Mystery of Anemonefish and Anemone Symbiosis

PubMed Central

Nedosyko, Anita M.; Young, Jeanne E.; Edwards, John W.; Burke da Silva, Karen

2014-01-01

Twenty-six species of anemonefish of the genera Amphiprion and monospecific Premnas, use only 10 species of anemones as hosts in the wild (Families: Actiniidae, Stichodactylidae and Thalassianthidae). Of these 10 anemone species some are used by multiple species of anemonefish while others have only a single anemonefish symbiont. Past studies have explored the different patterns of usage between anemonefish species and anemone species; however the evolution of this relationship remains unknown and has been little studied over the past decade. Here we reopen the case, comparing the toxicity of crude venoms obtained from anemones that host anemonefish as a way to investigate why some anemone species are used as a host more than others. Specifically, for each anemone species we investigated acute toxicity using Artemia francisca (LC50), haemolytic toxicity using ovine erythrocytes (EC50) and neurotoxicity using shore crabs (Ozius truncatus). We found that haemolytic and neurotoxic activity varied among host anemone species. Generally anemone species that displayed greater haemolytic activity also displayed high neurotoxic activity and tend to be more toxic on average as indicated by acute lethality analysis. An overall venom toxicity ranking for each anemone species was compared with the number of anemonefish species that are known to associate with each anemone species in the wild. Interestingly, anemones with intermediate toxicity had the highest number of anemonefish associates, whereas anemones with either very low or very high toxicity had the fewest anemonefish associates. These data demonstrate that variation in toxicity among host anemone species may be important in the establishment and maintenance of anemonefish anemone symbiosis. PMID:24878777

Searching for a toxic key to unlock the mystery of anemonefish and anemone symbiosis.

PubMed

Nedosyko, Anita M; Young, Jeanne E; Edwards, John W; Burke da Silva, Karen

2014-01-01

Twenty-six species of anemonefish of the genera Amphiprion and monospecific Premnas, use only 10 species of anemones as hosts in the wild (Families: Actiniidae, Stichodactylidae and Thalassianthidae). Of these 10 anemone species some are used by multiple species of anemonefish while others have only a single anemonefish symbiont. Past studies have explored the different patterns of usage between anemonefish species and anemone species; however the evolution of this relationship remains unknown and has been little studied over the past decade. Here we reopen the case, comparing the toxicity of crude venoms obtained from anemones that host anemonefish as a way to investigate why some anemone species are used as a host more than others. Specifically, for each anemone species we investigated acute toxicity using Artemia francisca (LC50), haemolytic toxicity using ovine erythrocytes (EC50) and neurotoxicity using shore crabs (Ozius truncatus). We found that haemolytic and neurotoxic activity varied among host anemone species. Generally anemone species that displayed greater haemolytic activity also displayed high neurotoxic activity and tend to be more toxic on average as indicated by acute lethality analysis. An overall venom toxicity ranking for each anemone species was compared with the number of anemonefish species that are known to associate with each anemone species in the wild. Interestingly, anemones with intermediate toxicity had the highest number of anemonefish associates, whereas anemones with either very low or very high toxicity had the fewest anemonefish associates. These data demonstrate that variation in toxicity among host anemone species may be important in the establishment and maintenance of anemonefish anemone symbiosis.

Bacterial Bioluminescence Regulates Expression of a Host Cryptochrome Gene in the Squid-Vibrio Symbiosis

PubMed Central

Heath-Heckman, Elizabeth A. C.; Peyer, Suzanne M.; Whistler, Cheryl A.; Apicella, Michael A.; Goldman, William E.; McFall-Ngai, Margaret J.

2013-01-01

ABSTRACT The symbiosis between the squid Euprymna scolopes and its luminous symbiont, Vibrio fischeri, is characterized by daily transcriptional rhythms in both partners and daily fluctuations in symbiont luminescence. In this study, we sought to determine whether symbionts affect host transcriptional rhythms. We identified two transcripts in host tissues (E. scolopes cry1 [escry1] and escry2) that encode cryptochromes, proteins that influence circadian rhythms in other systems. Both genes cycled daily in the head of the squid, with a pattern similar to that of other animals, in which expression of certain cry genes is entrained by environmental light. In contrast, escry1 expression cycled in the symbiont-colonized light organ with 8-fold upregulation coincident with the rhythms of bacterial luminescence, which are offset from the day/night light regime. Colonization of the juvenile light organ by symbionts was required for induction of escry1 cycling. Further, analysis with a mutant strain defective in light production showed that symbiont luminescence is essential for cycling of escry1; this defect could be complemented by presentation of exogenous blue light. However, blue-light exposure alone did not induce cycling in nonsymbiotic animals, but addition of molecules of the symbiont cell envelope to light-exposed animals did recover significant cycling activity, showing that light acts in synergy with other symbiont features to induce cycling. While symbiont luminescence may be a character specific to rhythms of the squid-vibrio association, resident microbial partners could similarly influence well-documented daily rhythms in other systems, such as the mammalian gut. PMID:23549919

Symbiosis of Arbuscular Mycorrhizal Fungi and Robinia pseudoacacia L. Improves Root Tensile Strength and Soil Aggregate Stability

PubMed Central

Zhang, Haoqiang; Liu, Zhenkun; Chen, Hui; Tang, Ming

2016-01-01

Robinia pseudoacacia L. (black locust) is a widely planted tree species on Loess Plateau for revegetation. Due to its symbiosis forming capability with arbuscular mycorrhizal (AM) fungi, we explored the influence of arbuscular mycorrhizal fungi on plant biomass, root morphology, root tensile strength and soil aggregate stability in a pot experiment. We inoculated R. pseudoacacia with/without AM fungus (Rhizophagus irregularis or Glomus versiforme), and measured root colonization, plant growth, root morphological characters, root tensile force and tensile strength, and parameters for soil aggregate stability at twelve weeks after inoculation. AM fungi colonized more than 70% plant root, significantly improved plant growth. Meanwhile, AM fungi elevated root morphological parameters, root tensile force, root tensile strength, Glomalin-related soil protein (GRSP) content in soil, and parameters for soil aggregate stability such as water stable aggregate (WSA), mean weight diameter (MWD) and geometric mean diameter (GMD). Root length was highly correlated with WSA, MWD and GMD, while hyphae length was highly correlated with GRSP content. The improved R. pseudoacacia growth, root tensile strength and soil aggregate stability indicated that AM fungi could accelerate soil fixation and stabilization with R. pseudoacacia, and its function in revegetation on Loess Plateau deserves more attention. PMID:27064570

Metal toxicity differently affects the Iris pseudacorus-arbuscular mycorrhiza fungi symbiosis in terrestrial and semi-aquatic habitats.

PubMed

Wężowicz, K; Turnau, K; Anielska, T; Zhebrak, I; Gołuszka, K; Błaszkowski, J; Rozpądek, P

2015-12-01

Phytoremediation offers an environmental friendly alternative to conventional cleanup techniques. In this study, mycorrhizal fungi isolated from the roots of Mentha longifolia grown in the basin of the Centuria River (S Poland) were used. Iris pseudacorus was grown in substratum from an industrial waste, enriched in Pb, Fe, Zn, and Cd in a terrestrial and water-logged habitat. Plant yield and photosynthetic performance was the highest in the aquatic environment; however, the presence of toxic metals (TM) negatively affected photosystem II (PSII) photochemistry as shown by the JIP test. Fungi colonization and Cd accumulation within plant tissues was decreased. In the terrestrial habitat, neither arbuscular mycorrhizal fungi (AMF) nor metal toxicity affected plant growth, although metal uptake, Cd in particular, as well as photosynthesis were affected. Inoculated plants accumulated significantly more Cd, and photosynthesis was downregulated. The results presented in this study clearly indicate that the I. pseudacorus-AMF symbiosis adapts itself to the presence of toxic metals in the environment, optimizing resource supply, energy fluxes, and possibly stress tolerance mechanisms. Plant/AMF consortia grown in terrestrial and water-logged habitats utilize different strategies to cope with metal toxicity. The use of AMF in improving the phytoremediation potential of I. pseudacorus needs, however, further research.

Symbiosis with an endobacterium increases the fitness of a mycorrhizal fungus, raising its bioenergetic potential.

PubMed

Salvioli, Alessandra; Ghignone, Stefano; Novero, Mara; Navazio, Lorella; Venice, Francesco; Bagnaresi, Paolo; Bonfante, Paola

2016-01-01

Arbuscular mycorrhizal fungi (AMF) occur in the rhizosphere and in plant tissues as obligate symbionts, having key roles in plant evolution and nutrition. AMF possess endobacteria, and genome sequencing of the endobacterium Candidatus Glomeribacter gigasporarum revealed a reduced genome and a dependence on the fungal host. To understand the effect of bacteria on fungal fitness, we used next-generation sequencing to analyse the transcriptional profile of Gigaspora margarita in the presence and in the absence of its endobacterium. Genomic data on AMF are limited; therefore, we first generated a gene catalogue for G. margarita. Transcriptome analysis revealed that the endobacterium has a stronger effect on the pre-symbiotic phase of the fungus. Coupling transcriptomics with cell biology and physiological approaches, we demonstrate that the bacterium increases the fungal sporulation success, raises the fungal bioenergetic capacity, increasing ATP production, and eliciting mechanisms to detoxify reactive oxygen species. By using TAT peptide to translocate the bioluminescent calcium reporter aequorin, we demonstrated that the line with endobacteria had a lower basal intracellular calcium concentration than the cured line. Lastly, the bacteria seem to enhance the fungal responsiveness to strigolactones, the plant molecules that AMF perceive as branching factors. Although the endobacterium exacts a nutritional cost on the AMF, endobacterial symbiosis improves the fungal ecological fitness by priming mitochondrial metabolic pathways and giving the AMF more tools to face environmental stresses. Thus, we hypothesise that, as described for the human microbiota, endobacteria may increase AMF innate immunity.

Key Transport and Ammonia Recycling Genes Involved in Aphid Symbiosis Respond to Host-Plant Specialization.

PubMed

Kim, Dohyup; Minhas, Bushra F; Li-Byarlay, Hongmei; Hansen, Allison K

2018-05-25

Microbes are known to influence insect-plant interactions; however, it is unclear if host-plant diet influences the regulation of nutritional insect symbioses. The pea aphid, Acyrthosiphon pisum , requires its nutritional endosymbiont, Buchnera , for the production of essential amino acids. We hypothesize that key aphid genes that regulate the nutritional symbioses respond to host-plant diet when aphids feed on a specialized (alfalfa) compared to a universal host-plant diet (fava), which vary in amino acid profiles. Using RNA-Seq and whole genome bisulfite sequencing, we measured gene expression and DNA methylation profiles for such genes when aphids fed on either their specialized or universal host-plant diets. Our results reveal that when aphids feed on their specialized host-plant they significantly up-regulate and/or hypo-methylate key aphid genes in bacteriocytes related to the amino acid metabolism, including glutamine synthetase in the GOGAT cycle that recycles ammonia into glutamine and the glutamine transporter ApGLNT1 Moreover, regardless of what host-plant aphids feed on we observed significant up-regulation and differential methylation of key genes involved in the amino acid metabolism and the glycine/serine metabolism, a metabolic program observed in proliferating cancer cells potentially to combat oxidative stress. Based on our results, we suggest that this regulatory response of key symbiosis genes in bacteriocytes allows aphids to feed on a suboptimal host-plant that they specialize on. Copyright © 2018, G3: Genes, Genomes, Genetics.

Symbiosis with an endobacterium increases the fitness of a mycorrhizal fungus, raising its bioenergetic potential

PubMed Central

Salvioli, Alessandra; Ghignone, Stefano; Novero, Mara; Navazio, Lorella; Venice, Francesco; Bagnaresi, Paolo; Bonfante, Paola

2016-01-01

Arbuscular mycorrhizal fungi (AMF) occur in the rhizosphere and in plant tissues as obligate symbionts, having key roles in plant evolution and nutrition. AMF possess endobacteria, and genome sequencing of the endobacterium Candidatus Glomeribacter gigasporarum revealed a reduced genome and a dependence on the fungal host. To understand the effect of bacteria on fungal fitness, we used next-generation sequencing to analyse the transcriptional profile of Gigaspora margarita in the presence and in the absence of its endobacterium. Genomic data on AMF are limited; therefore, we first generated a gene catalogue for G. margarita. Transcriptome analysis revealed that the endobacterium has a stronger effect on the pre-symbiotic phase of the fungus. Coupling transcriptomics with cell biology and physiological approaches, we demonstrate that the bacterium increases the fungal sporulation success, raises the fungal bioenergetic capacity, increasing ATP production, and eliciting mechanisms to detoxify reactive oxygen species. By using TAT peptide to translocate the bioluminescent calcium reporter aequorin, we demonstrated that the line with endobacteria had a lower basal intracellular calcium concentration than the cured line. Lastly, the bacteria seem to enhance the fungal responsiveness to strigolactones, the plant molecules that AMF perceive as branching factors. Although the endobacterium exacts a nutritional cost on the AMF, endobacterial symbiosis improves the fungal ecological fitness by priming mitochondrial metabolic pathways and giving the AMF more tools to face environmental stresses. Thus, we hypothesise that, as described for the human microbiota, endobacteria may increase AMF innate immunity. PMID:26046255

Cooperation through Competition-Dynamics and Microeconomics of a Minimal Nutrient Trade System in Arbuscular Mycorrhizal Symbiosis.

PubMed

Schott, Stephan; Valdebenito, Braulio; Bustos, Daniel; Gomez-Porras, Judith L; Sharma, Tripti; Dreyer, Ingo

2016-01-01

In arbuscular mycorrhizal (AM) symbiosis, fungi and plants exchange nutrients (sugars and phosphate, for instance) for reciprocal benefit. Until now it is not clear how this nutrient exchange system works. Here, we used computational cell biology to simulate the dynamics of a network of proton pumps and proton-coupled transporters that are upregulated during AM formation. We show that this minimal network is sufficient to describe accurately and realistically the nutrient trade system. By applying basic principles of microeconomics, we link the biophysics of transmembrane nutrient transport with the ecology of organismic interactions and straightforwardly explain macroscopic scenarios of the relations between plant and AM fungus. This computational cell biology study allows drawing far reaching hypotheses about the mechanism and the regulation of nutrient exchange and proposes that the "cooperation" between plant and fungus can be in fact the result of a competition between both for the same resources in the tiny periarbuscular space. The minimal model presented here may serve as benchmark to evaluate in future the performance of more complex models of AM nutrient exchange. As a first step toward this goal, we included SWEET sugar transporters in the model and show that their co-occurrence with proton-coupled sugar transporters results in a futile carbon cycle at the plant plasma membrane proposing that two different pathways for the same substrate should not be active at the same time.

Effect of TiO2 nanoparticles on aerobic granulation of algal-bacterial symbiosis system and nutrients removal from synthetic wastewater.

PubMed

Li, Bing; Huang, Wenli; Zhang, Chao; Feng, Sisi; Zhang, Zhenya; Lei, Zhongfang; Sugiura, Norio

2015-01-01

The influence of TiO2 nanoparticles (TiO2-NPs) (10-50mg/L) on aerobic granulation of algal-bacterial symbiosis system was investigated by using two identical sequencing batch reactors (SBRs). Although little adverse effect was observed on their nitritation efficiency (98-100% in both reactors), algal-bacterial granules in the control SBR (Rc) gradually lost stability mainly brought about by algae growth. TiO2-NPs addition to RT was found to enhance the granulation process achieving stable and compact algal-bacterial granules with remarkably improved nitratation thus little nitrite accumulation in RT when influent TiO2-NPs⩾30mg/L. Despite almost similar organics and phosphorus removals obtained in both reactors, the stably high nitratation efficiency in addition to much stable granular structure in RT suggests that TiO2-NPs addition might be a promising remedy for the long-term operation of algal-bacterial granular system, most probably attributable to the stimulated excretion of extracellular polymeric substances and less filamentous TM7. Copyright © 2015 Elsevier Ltd. All rights reserved.

Strategies for sustainable development of industrial park in Ulsan, South Korea--from spontaneous evolution to systematic expansion of industrial symbiosis.

PubMed

Park, Hung-Suck; Rene, Eldon R; Choi, Soo-Mi; Chiu, Anthony S F

2008-04-01

The Korea National Cleaner Production Center (KNCPC) affiliated to the Korea Institute of Industrial Technology (KITECH) has started a 15 year, 3-phase EIP master plan with the support of Ministry of Commerce, Industry, and Energy (MOCIE). A total of 6 industrial parks, including industrial parks in Ulsan city, known as the industrial capital of South Korea, are planning projects to find the feasibility of shifting existing industrial parks to eco-industrial parks. The basic survey shows that Ulsan industrial complex has been continuously evolving from conventional industrial complexes to eco-industrial parks by spontaneous industrial symbiosis. This paper describes the Korean national policies and the developmental activities of this vision to drive the global trend of innovation for converting the existing industrial parks to eco-industrial parks through inter-industry waste, energy, and material exchange in Ulsan Industrial complexes. In addition, the primary and supportive components of the Ulsan EIP pilot project, which will be implemented for 5 years is elaborated with its schedules and economic benefits.

Artificial symbiosis for acetone-butanol-ethanol (ABE) fermentation from alkali extracted deshelled corn cobs by co-culture of Clostridium beijerinckii and Clostridium cellulovorans.

PubMed

Wen, Zhiqiang; Wu, Mianbin; Lin, Yijun; Yang, Lirong; Lin, Jianping; Cen, Peilin

2014-07-15

-culturing process, which figured out the roles of each strain at different periods in the symbiosis. Our work illustrated the great potential of artificial symbiosis in biofuel production from lignocellulosic biomass by CBP. The dynamics of the abundance of C. beijerinckii and C. cellulovorans revealed mechanisms of cooperation and competition between the two strains during the co-culture process.

Lipo-chitin oligosaccharides, plant symbiosis signalling molecules that modulate mammalian angiogenesis in vitro.

PubMed

Djordjevic, Michael A; Bezos, Anna; Susanti; Marmuse, Laurence; Driguez, Hugues; Samain, Eric; Vauzeilles, Boris; Beau, Jean-Marie; Kordbacheh, Farzaneh; Rolfe, Barry G; Schwörer, Ralf; Daines, Alison M; Gresshoff, Peter M; Parish, Christopher R

2014-01-01

Lipochitin oligosaccharides (LCOs) are signaling molecules required by ecologically and agronomically important bacteria and fungi to establish symbioses with diverse land plants. In plants, oligo-chitins and LCOs can differentially interact with different lysin motif (LysM) receptors and affect innate immunity responses or symbiosis-related pathways. In animals, oligo-chitins also induce innate immunity and other physiological responses but LCO recognition has not been demonstrated. Here LCO and LCO-like compounds are shown to be biologically active in mammals in a structure dependent way through the modulation of angiogenesis, a tightly-regulated process involving the induction and growth of new blood vessels from existing vessels. The testing of 24 LCO, LCO-like or oligo-chitin compounds resulted in structure-dependent effects on angiogenesis in vitro leading to promotion, or inhibition or nil effects. Like plants, the mammalian LCO biological activity depended upon the presence and type of terminal substitutions. Un-substituted oligo-chitins of similar chain lengths were unable to modulate angiogenesis indicating that mammalian cells, like plant cells, can distinguish between LCOs and un-substituted oligo-chitins. The cellular mode-of-action of the biologically active LCOs in mammals was determined. The stimulation or inhibition of endothelial cell adhesion to vitronectin or fibronectin correlated with their pro- or anti-angiogenic activity. Importantly, novel and more easily synthesised LCO-like disaccharide molecules were also biologically active and de-acetylated chitobiose was shown to be the primary structural basis of recognition. Given this, simpler chitin disaccharides derivatives based on the structure of biologically active LCOs were synthesised and purified and these showed biological activity in mammalian cells. Since important chronic disease states are linked to either insufficient or excessive angiogenesis, LCO and LCO-like molecules may have the

Crosstalk of Signaling Mechanisms Involved in Host Defense and Symbiosis Against Microorganisms in Rice.

PubMed

Akamatsu, Akira; Shimamoto, Ko; Kawano, Yoji

2016-08-01

Rice is one of the most important food crops, feeding about half population in the world. Rice pathogens cause enormous damage to rice production worldwide. In plant immunity research, considerable progress has recently been made in our understanding of the molecular mechanisms underlying microbe-associated molecular pattern (MAMP)-triggered immunity. Using genome sequencing and molecular techniques, a number of new MAMPs and their receptors have been identified in the past two decades. Notably, the mechanisms for chitin perception via the lysine motif (LysM) domain-containing receptor OsCERK1, as well as the mechanisms for bacterial MAMP (e.g. flg22, elf18) perception via the leucine-rich repeat (LRR) domain-containing receptors FLS2 and EFR, have been clarified in rice and Arabidopsis, respectively. In chitin signaling in rice, two direct substrates of OsCERK1, Rac/ROP GTPase guanine nucleotide exchange factor OsRacGEF1 and receptor-like cytoplasmic kinase OsRLCK185, have been identified as components of the OsCERK1 complex and are rapidly phosphorylated by OsCERK1 in response to chitin. Interestingly, OsCERK1 also participates in symbiosis with arbuscular mycorrhizal fungi (AMF) in rice and plays a role in the recognition of short-chitin molecules (CO4/5), which are symbiotic signatures included in AMF germinated spore exudates and induced by synthetic strigolactone. Thus, OsCERK1 contributes to both immunity and symbiotic responses. In this review, we describe recent studies on pathways involved in rice immunity and symbiotic signaling triggered by interactions with microorganisms. In addition, we describe recent advances in genetic engineering by using plant immune receptors and symbiotic microorganisms to enhance disease resistance of rice.

Integrating robotic action with biologic perception: A brain-machine symbiosis theory

NASA Astrophysics Data System (ADS)

Mahmoudi, Babak

In patients with motor disability the natural cyclic flow of information between the brain and external environment is disrupted by their limb impairment. Brain-Machine Interfaces (BMIs) aim to provide new communication channels between the brain and environment by direct translation of brain's internal states into actions. For enabling the user in a wide range of daily life activities, the challenge is designing neural decoders that autonomously adapt to different tasks, environments, and to changes in the pattern of neural activity. In this dissertation, a novel decoding framework for BMIs is developed in which a computational agent autonomously learns how to translate neural states into action based on maximization of a measure of shared goal between user and the agent. Since the agent and brain share the same goal, a symbiotic relationship between them will evolve therefore this decoding paradigm is called a Brain-Machine Symbiosis (BMS) framework. A decoding agent was implemented within the BMS framework based on the Actor-Critic method of Reinforcement Learning. The rule of the Actor as a neural decoder was to find mapping between the neural representation of motor states in the primary motor cortex (MI) and robot actions in order to solve reaching tasks. The Actor learned the optimal control policy using an evaluative feedback that was estimated by the Critic directly from the user's neural activity of the Nucleus Accumbens (NAcc). Through a series of computational neuroscience studies in a cohort of rats it was demonstrated that NAcc could provide a useful evaluative feedback by predicting the increase or decrease in the probability of earning reward based on the environmental conditions. Using a closed-loop BMI simulator it was demonstrated the Actor-Critic decoding architecture was able to adapt to different tasks as well as changes in the pattern of neural activity. The custom design of a dual micro-wire array enabled simultaneous implantation of MI and

Cooperation through Competition—Dynamics and Microeconomics of a Minimal Nutrient Trade System in Arbuscular Mycorrhizal Symbiosis

PubMed Central

Schott, Stephan; Valdebenito, Braulio; Bustos, Daniel; Gomez-Porras, Judith L.; Sharma, Tripti; Dreyer, Ingo

2016-01-01

In arbuscular mycorrhizal (AM) symbiosis, fungi and plants exchange nutrients (sugars and phosphate, for instance) for reciprocal benefit. Until now it is not clear how this nutrient exchange system works. Here, we used computational cell biology to simulate the dynamics of a network of proton pumps and proton-coupled transporters that are upregulated during AM formation. We show that this minimal network is sufficient to describe accurately and realistically the nutrient trade system. By applying basic principles of microeconomics, we link the biophysics of transmembrane nutrient transport with the ecology of organismic interactions and straightforwardly explain macroscopic scenarios of the relations between plant and AM fungus. This computational cell biology study allows drawing far reaching hypotheses about the mechanism and the regulation of nutrient exchange and proposes that the “cooperation” between plant and fungus can be in fact the result of a competition between both for the same resources in the tiny periarbuscular space. The minimal model presented here may serve as benchmark to evaluate in future the performance of more complex models of AM nutrient exchange. As a first step toward this goal, we included SWEET sugar transporters in the model and show that their co-occurrence with proton-coupled sugar transporters results in a futile carbon cycle at the plant plasma membrane proposing that two different pathways for the same substrate should not be active at the same time. PMID:27446142

Increased Fitness of Rice Plants to Abiotic Stress Via Habitat Adapted Symbiosis: A Strategy for Mitigating Impacts of Climate Change

PubMed Central

Redman, Regina S.; Kim, Yong Ok; Woodward, Claire J. D. A.; Greer, Chris; Espino, Luis; Doty, Sharon L.; Rodriguez, Rusty J.

2011-01-01

Climate change and catastrophic events have contributed to rice shortages in several regions due to decreased water availability and soil salinization. Although not adapted to salt or drought stress, two commercial rice varieties achieved tolerance to these stresses by colonizing them with Class 2 fungal endophytes isolated from plants growing across moisture and salinity gradients. Plant growth and development, water usage, ROS sensitivity and osmolytes were measured with and without stress under controlled conditions. The endophytes conferred salt, drought and cold tolerance to growth chamber and greenhouse grown plants. Endophytes reduced water consumption by 20–30% and increased growth rate, reproductive yield, and biomass of greenhouse grown plants. In the absence of stress, there was no apparent cost of the endophytes to plants, however, endophyte colonization decreased from 100% at planting to 65% compared to greenhouse plants grown under continual stress (maintained 100% colonization). These findings indicate that rice plants can exhibit enhanced stress tolerance via symbiosis with Class 2 endophytes, and suggest that symbiotic technology may be useful in mitigating impacts of climate change on other crops and expanding agricultural production onto marginal lands. PMID:21750695

Insights into archaeal evolution and symbiosis from the genomes of a Nanoarchaeon and its crenarchaeal host from Yellowstone National Park

DOE Office of Scientific and Technical Information (OSTI.GOV)

Podar, Mircea; Graham, David E; Reysenbach, Anna-Louise

A hyperthemophilic member of the Nanoarchaeota from Obsidian Pool, a thermal feature in Yellowstone National Park was characterized using single cell isolation and sequencing, together with its putative host, a Sulfolobales archaeon. This first representative of a non-marine Nanoarchaeota (Nst1) resembles Nanoarchaeum equitans by lacking most biosynthetic capabilities, the two forming a deep-branching archaeal lineage. However, the Nst1 genome is over 20% larger, encodes a complete gluconeogenesis pathway and a full complement of archaeal flagellum proteins. Comparison of the two genomes suggests that the marine and terrestrial Nanoarchaeota lineages share a common ancestor that was already a symbiont of anothermore » archaeon. With a larger genome, a smaller repertoire of split protein encoding genes and no split non-contiguous tRNAs, Nst1 appears to have experienced less severe genome reduction than N. equitans. The inferred host of Nst1 is potentially autotrophic, with a streamlined genome and simplified central and energetic metabolism as compared to other Sulfolobales. The two distinct Nanoarchaeota-host genomic data sets offer insights into the evolution of archaeal symbiosis and parasitism and will further enable studies of the cellular and molecular mechanisms of these relationships.« less

Increased fitness of rice plants to abiotic stress via habitat adapted symbiosis: A strategy for mitigating impacts of climate change

USGS Publications Warehouse

Redman, R.S.; Kim, Y.-O.; Woodward, C.J.D.A.; Greer, C.; Espino, L.; Doty, S.L.; Rodriguez, R.J.

2011-01-01

Climate change and catastrophic events have contributed to rice shortages in several regions due to decreased water availability and soil salinization. Although not adapted to salt or drought stress, two commercial rice varieties achieved tolerance to these stresses by colonizing them with Class 2 fungal endophytes isolated from plants growing across moisture and salinity gradients. Plant growth and development, water usage, ROS sensitivity and osmolytes were measured with and without stress under controlled conditions. The endophytes conferred salt, drought and cold tolerance to growth chamber and greenhouse grown plants. Endophytes reduced water consumption by 20–30% and increased growth rate, reproductive yield, and biomass of greenhouse grown plants. In the absence of stress, there was no apparent cost of the endophytes to plants, however, endophyte colonization decreased from 100% at planting to 65% compared to greenhouse plants grown under continual stress (maintained 100% colonization). These findings indicate that rice plants can exhibit enhanced stress tolerance via symbiosis with Class 2 endophytes, and suggest that symbiotic technology may be useful in mitigating impacts of climate change on other crops and expanding agricultural production onto marginal lands.

Investigating the causes and consequences of symbiont shuffling in a multi-partner reef coral symbiosis under environmental change.

PubMed

Cunning, R; Silverstein, R N; Baker, A C

2015-06-22

Dynamic symbioses may critically mediate impacts of climate change on diverse organisms, with repercussions for ecosystem persistence in some cases. On coral reefs, increases in heat-tolerant symbionts after thermal bleaching can reduce coral susceptibility to future stress. However, the relevance of this adaptive response is equivocal owing to conflicting reports of symbiont stability and change. We help reconcile this conflict by showing that change in symbiont community composition (symbiont shuffling) in Orbicella faveolata depends on the disturbance severity and recovery environment. The proportion of heat-tolerant symbionts dramatically increased following severe experimental bleaching, especially in a warmer recovery environment, but tended to decrease if bleaching was less severe. These patterns can be explained by variation in symbiont performance in the changing microenvironments created by differentially bleached host tissues. Furthermore, higher proportions of heat-tolerant symbionts linearly increased bleaching resistance but reduced photochemical efficiency, suggesting that any change in community structure oppositely impacts performance and stress tolerance. Therefore, even minor symbiont shuffling can adaptively benefit corals, although fitness effects of resulting trade-offs are difficult to predict. This work helps elucidate causes and consequences of dynamism in symbiosis, which is critical to predicting responses of multi-partner symbioses such as O. faveolata to environmental change. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

Characterization of Novel Plant Symbiosis Mutants Using a New Multiple Gene-Expression Reporter Sinorhizobium meliloti Strain

PubMed Central

Lang, Claus; Smith, Lucinda S.; Haney, Cara H.; Long, Sharon R.

2018-01-01

The formation of nitrogen fixing root nodules by Medicago truncatula and Sinorhizobium meliloti requires communication between both organisms and coordinated differentiation of plant and bacterial cells. After an initial signal exchange, the bacteria invade the tissue of the growing nodule via plant-derived tubular structures, called infection threads. The bacteria are released from the infection threads into invasion-competent plant cells, where they differentiate into nitrogen-fixing bacteroids. Both organisms undergo dramatic transcriptional, metabolic and morphological changes during nodule development. To identify plant processes that are essential for the formation of nitrogen fixing nodules after nodule development has been initiated, large scale mutageneses have been conducted to discover underlying plant symbiosis genes. Such screens yield numerous uncharacterized plant lines with nitrogen fixation deficient nodules. In this study, we report construction of a S. meliloti strain carrying four distinct reporter constructs to reveal stages of root nodule development. The strain contains a constitutively expressed lacZ reporter construct; a PexoY-mTFP fusion that is expressed in infection threads but not in differentiated bacteroids; a PbacA-mcherry construct that is expressed in infection threads and during bacteroid differentiation; and a PnifH-uidA construct that is expressed during nitrogen fixation. We used this strain together with fluorescence microscopy to study nodule development over time in wild type nodules and to characterize eight plant mutants from a fast neutron bombardment screen. Based on the signal intensity and the localization patterns of the reporter genes, we grouped mutants with similar phenotypes and placed them in a developmental context. PMID:29467773

Characterization of Novel Plant Symbiosis Mutants Using a New Multiple Gene-Expression Reporter Sinorhizobium meliloti Strain.

PubMed

Lang, Claus; Smith, Lucinda S; Long, Sharon R

2018-01-01

The formation of nitrogen fixing root nodules by Medicago truncatula and Sinorhizobium meliloti requires communication between both organisms and coordinated differentiation of plant and bacterial cells. After an initial signal exchange, the bacteria invade the tissue of the growing nodule via plant-derived tubular structures, called infection threads. The bacteria are released from the infection threads into invasion-competent plant cells, where they differentiate into nitrogen-fixing bacteroids. Both organisms undergo dramatic transcriptional, metabolic and morphological changes during nodule development. To identify plant processes that are essential for the formation of nitrogen fixing nodules after nodule development has been initiated, large scale mutageneses have been conducted to discover underlying plant symbiosis genes. Such screens yield numerous uncharacterized plant lines with nitrogen fixation deficient nodules. In this study, we report construction of a S. meliloti strain carrying four distinct reporter constructs to reveal stages of root nodule development. The strain contains a constitutively expressed lacZ reporter construct; a P exoY -mTFP fusion that is expressed in infection threads but not in differentiated bacteroids; a P bacA -mcherry construct that is expressed in infection threads and during bacteroid differentiation; and a P nifH -uidA construct that is expressed during nitrogen fixation. We used this strain together with fluorescence microscopy to study nodule development over time in wild type nodules and to characterize eight plant mutants from a fast neutron bombardment screen. Based on the signal intensity and the localization patterns of the reporter genes, we grouped mutants with similar phenotypes and placed them in a developmental context.

New insights into carbon acquisition and exchanges within the coral–dinoflagellate symbiosis under NH4+ and NO3− supply

PubMed Central

Ezzat, Leïla; Maguer, Jean-François; Grover, Renaud; Ferrier-Pagès, Christine

2015-01-01

Anthropogenic nutrient enrichment affects the biogeochemical cycles and nutrient stoichiometry of coastal ecosystems and is often associated with coral reef decline. However, the mechanisms by which dissolved inorganic nutrients, and especially nitrogen forms (ammonium versus nitrate) can disturb the association between corals and their symbiotic algae are subject to controversial debate. Here, we investigated the coral response to varying N : P ratios, with nitrate or ammonium as a nitrogen source. We showed significant differences in the carbon acquisition by the symbionts and its allocation within the symbiosis according to nutrient abundance, type and stoichiometry. In particular, under low phosphate concentration (0.05 µM), a 3 µM nitrate enrichment induced a significant decrease in carbon fixation rate and low values of carbon translocation, compared with control conditions (N : P = 0.5 : 0.05), while these processes were significantly enhanced when nitrate was replaced by ammonium. A combined enrichment in ammonium and phosphorus (N : P = 3 : 1) induced a shift in nutrient allocation to the symbionts, at the detriment of the host. Altogether, these results shed light into the effect of nutrient enrichment on reef corals. More broadly, they improve our understanding of the consequences of nutrient loading on reef ecosystems, which is urgently required to refine risk management strategies. PMID:26203006

Functional analysis of liverworts in dual symbiosis with Glomeromycota and Mucoromycotina fungi under a simulated Palaeozoic CO2 decline

PubMed Central

Field, Katie J; Rimington, William R; Bidartondo, Martin I; Allinson, Kate E; Beerling, David J; Cameron, Duncan D; Duckett, Jeffrey G; Leake, Jonathan R; Pressel, Silvia

2016-01-01

Most land plants form mutualistic associations with arbuscular mycorrhizal fungi of the Glomeromycota, but recent studies have found that ancient plant lineages form mutualisms with Mucoromycotina fungi. Simultaneous associations with both fungal lineages have now been found in some plants, necessitating studies to understand the functional and evolutionary significance of these tripartite associations for the first time. We investigate the physiology and cytology of dual fungal symbioses in the early-diverging liverworts Allisonia and Neohodgsonia at modern and Palaeozoic-like elevated atmospheric CO2 concentrations under which they are thought to have evolved. We found enhanced carbon cost to liverworts with simultaneous Mucoromycotina and Glomeromycota associations, greater nutrient gain compared with those symbiotic with only one fungal group in previous experiments and contrasting responses to atmospheric CO2 among liverwort–fungal symbioses. In liverwort–Mucoromycotina symbioses, there is increased P-for-C and N-for-C exchange efficiency at 440 p.p.m. compared with 1500 p.p.m. CO2. In liverwort–Glomeromycota symbioses, P-for-C exchange is lower at ambient CO2 compared with elevated CO2. No characteristic cytologies of dual symbiosis were identified. We provide evidence of a distinct physiological niche for plant symbioses with Mucoromycotina fungi, giving novel insight into why dual symbioses with Mucoromycotina and Glomeromycota fungi persist to the present day. PMID:26613340

Teasing apart a three-way symbiosis: transcriptome analyses of Curvularia protuberata in response to viral infection and heat stress.

PubMed

Morsy, Mustafa R; Oswald, Jennifer; He, Ji; Tang, Yuhong; Roossinck, Marilyn J

2010-10-15

The fungus Curvularia protuberata carries a dsRNA virus, Curvularia thermal tolerance virus, and develops a three-way symbiotic relationship with plants to enable their survival in extreme soil temperatures. To learn about the genome of C. protuberata and possible mechanisms of heat tolerance a collection of expressed sequence tags (ESTs) were developed from two subtracted cDNA libraries from mycelial cultures grown under control and heat stress conditions. We analyzed 4207 ESTs that were assembled into 1926 unique transcripts. Of the unique transcripts, 1347 (70%) had sequence similarity with GenBank entries using BLASTX while the rest represented unknown proteins with no matches in the databases. The majority of ESTs with known similarities were homologues to fungal genes. The EST collection presents a rich source of heat stress and viral induced genes of a fungal endophyte that is involved in a symbiotic relationship with plants. Expression profile analyses of some candidate genes suggest possible involvement of osmoprotectants such as trehalose, glycine betaine, and taurine in the heat stress response. The fungal pigment melanin, and heat shock proteins also may be involved in the thermotolerance of C. protuberata in culture. The results assist in understanding the molecular basis of thermotolerance of the three-way symbiosis. Further studies will confirm or refute the involvement of these pathways in stress tolerance. Copyright © 2010 Elsevier Inc. All rights reserved.

New velocimetry and revised cartography of the spiral arms in the Milky Way—a consistent symbiosis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vallée, Jacques P., E-mail: jacques.vallee@cnrc.gc.ca

Recent advances in the determinations of the positions (pitch angle, shape, numbers, interarm separation) and velocities (rotation curve) of the spiral arms are evaluated and compared to previous determinations. Based on these results, an average cartographic model is developed that fits the means of basic input data and provides predictions for the locations of the arms in the Milky Way, for each galactic quadrant. For each spiral arm segment in each galactic quadrant, the LSR radial velocities are calculated for the radial distance as well as for its galactic longitude. From our velocimetric model, arm intercepts (between line of sightsmore » and spiral arms) are indicated in velocity space and may be used to find the distance and velocity to any arm, in a given longitude range. Velocity comparisons between model predictions and published CO velocity distribution are done for each galactic quadrant, with good results. Our velocimetric model is not hydromagnetic in character, nor is it a particle-simulation scheme, yet it is simple to use for comparisons with the observations and it is in symbiosis and consistent with our cartographic model (itself simple to use for comparisons with observations). A blending in velocity of the Perseus and Cygnus arms is further demonstrated, as well as an apparent longitude-velocity blending of the starting points of the four spiral arms near 4 kpc (not a physical ring). An integrated (distance, velocity) model for the mass in the disk is employed, to yield the total mass of 3.0 × 10{sup 11} M{sub ☉} within a galactic radius of 28 kpc.« less

A Legume TOR Protein Kinase Regulates Rhizobium Symbiosis and Is Essential for Infection and Nodule Development1[OPEN

PubMed Central

Blanco, Lourdes; Quinto, Carmen

2016-01-01

The target of rapamycin (TOR) protein kinase regulates metabolism, growth, and life span in yeast, animals, and plants in coordination with nutrient status and environmental conditions. The nutrient-dependent nature of TOR functionality makes this kinase a putative regulator of symbiotic associations involving nutrient acquisition. However, TOR’s role in these processes remains to be understood. Here, we uncovered the role of TOR during the bean (Phaseolus vulgaris)-Rhizobium tropici (Rhizobium) symbiotic interaction. TOR was expressed in all tested bean tissues, with higher transcript levels in the root meristems and senesced nodules. We showed TOR promoter expression along the progressing infection thread and in the infected cells of mature nodules. Posttranscriptional gene silencing of TOR using RNA interference (RNAi) showed that this gene is involved in lateral root elongation and root cell organization and also alters the density, size, and number of root hairs. The suppression of TOR transcripts also affected infection thread progression and associated cortical cell divisions, resulting in a drastic reduction of nodule numbers. TOR-RNAi resulted in reduced reactive oxygen species accumulation and altered CyclinD1 and CyclinD3 expression, which are crucial factors for infection thread progression and nodule organogenesis. Enhanced expression of TOR-regulated ATG genes in TOR-RNAi roots suggested that TOR plays a role in the recognition of Rhizobium as a symbiont. Together, these data suggest that TOR plays a vital role in the establishment of root nodule symbiosis in the common bean. PMID:27698253

Refining the Roots of the Beewolf-Streptomyces Symbiosis: Antennal Symbionts in the Rare Genus Philanthinus (Hymenoptera, Crabronidae)

PubMed Central

Yildirim, Erol; Gürbüz, M. Faruk; Herzner, Gudrun; Strohm, Erhard

2012-01-01

Insects engage in symbiotic associations with a large diversity of beneficial microorganisms. While the majority of well-studied symbioses have a nutritional basis, several cases are known in which bacteria protect their host from pathogen infestation. Solitary wasps of the genera Philanthus and Trachypus (beewolves; Hymenoptera, Crabronidae) cultivate the actinomycete “Candidatus Streptomyces philanthi” in specialized antennal gland reservoirs. The symbionts are transferred to the larval cocoon, where they provide protection against pathogenic fungi by producing at least nine different antibiotics. Here we investigated the closest relatives of Philanthus and Trachypus, the rare genus Philanthinus, for the presence of antennal gland reservoirs and symbiotic streptomycetes. Molecular analyses identified “Ca. Streptomyces philanthi” in reservoirs of Philanthinus quattuordecimpunctatus. Phylogenies based on the 16S rRNA gene suggest that P. quattuordecimpunctatus may have acquired “Ca. Streptomyces philanthi” by horizontal transfer from other beewolf species. In histological sections and three-dimensional reconstructions, the antennal gland reservoirs were found to occupy six antennal segments (as opposed to only five in Philanthus and Trachypus) and to be structurally less complex than those of the evolutionarily more derived genera of beewolves. The presence of “Ca. Streptomyces philanthi” in antennal glands of Philanthinus indicates that the symbiosis between beewolves and Streptomyces bacteria is much older than previously thought. It probably evolved along the branch leading to the monophyletic tribe Philanthini, as it seems to be confined to the genera Philanthus, Trachypus, and Philanthinus, which together comprise 172 described species of solitary wasps. PMID:22113914

Identification of a gene from the arbuscular mycorrhizal fungus Glomus intraradices encoding for a 14-3-3 protein that is up-regulated by drought stress during the AM symbiosis.

PubMed

Porcel, Rosa; Aroca, Ricardo; Cano, Custodia; Bago, Alberto; Ruiz-Lozano, Juan Manuel

2006-10-01

In the present study, a 14-3-3 protein-encoding gene from Glomus intraradices has been identified after differential hybridization of a cDNA library constructed from the fungus growing in vitro and subjected to drought stress by addition of 25% PEG 6000. Subsequently, we have studied its expression pattern under drought stress in vitro and also when forming natural symbioses with different host plants. The results obtained suggest that Gi14-3-3 gene may be involved in the protection that the arbuscular mycorrhizal (AM) symbiosis confers to the host plant against drought stress. Our findings provide new evidences that the contribution of AM fungi to the enhanced drought tolerance of the host plant can be mediated by a group of proteins (the 14-3-3) that regulate both signaling pathways and also effector proteins involved in the final plant responses.

Mutualistic Symbiosis between Researchers and Educators: the Case of Two Education Officers on the Joides Resolution

NASA Astrophysics Data System (ADS)

Cicconi, Alessia; Burgio, Marion; Cooper, Sharon

2017-04-01

Geoscience education from the primary school through the high school level is highly effected by the way teachers themselves deal with the teaching of science. Many studies on science education in general have found that teachers who lack research experience are less confident in teaching science with an inquiry methodology - the way that reflects how science really works and is found the most effective regarding students' achievement in science and their confidence in addressing STEM careers. The International Ocean Discovery Program (IODP) has carried out for years an education and outreach program that involves educators and teachers, with the position of Education Officer, in the expeditions on board the JOIDES Resolution (JR), an oceanographic vessel specialized in drilling ocean sediment cores for research purposes. This immersive experience gives teachers the opportunity to be part of the research process with the aim, among many others, to fill the gap that sometimes exists between how science is explained in textbooks and the real practice of scientific research. Using a scientific parallel, having teachers working with researchers could be considered a mutualistic symbiosis: on one hand researchers have a job, usually difficult to understand for the public and made simple by the teacher; on the other hand the teacher, working with researchers as a researcher will gain more confidence using an inquiry methodology in teaching science. In this oral presentation we want to present the outcomes of the outreach projects of two Education Officers, the first one who participated in Expedition 360 and the second one that will take part in the Expedition 367, in terms of 1) their perception and opinion of this immersive experience seen as professional development; 2) perceptions and opinions of teachers involved from shore, with or without their classes. This exploratory study has carried out with qualitative and quantitative methodology using questionnaires and

Arbuscular mycorrhizal symbiosis increases relative apoplastic water flow in roots of the host plant under both well-watered and drought stress conditions.

PubMed

Bárzana, Gloria; Aroca, Ricardo; Paz, José Antonio; Chaumont, François; Martinez-Ballesta, Mari Carmen; Carvajal, Micaela; Ruiz-Lozano, Juan Manuel

2012-04-01

The movement of water through mycorrhizal fungal tissues and between the fungus and roots is little understood. It has been demonstrated that arbuscular mycorrhizal (AM) symbiosis regulates root hydraulic properties, including root hydraulic conductivity. However, it is not clear whether this effect is due to a regulation of root aquaporins (cell-to-cell pathway) or to enhanced apoplastic water flow. Here we measured the relative contributions of the apoplastic versus the cell-to-cell pathway for water movement in roots of AM and non-AM plants. We used a combination of two experiments using the apoplastic tracer dye light green SF yellowish and sodium azide as an inhibitor of aquaporin activity. Plant water and physiological status, root hydraulic conductivity and apoplastic water flow were measured. Roots of AM plants enhanced significantly relative apoplastic water flow as compared with non-AM plants and this increase was evident under both well-watered and drought stress conditions. The presence of the AM fungus in the roots of the host plants was able to modulate the switching between apoplastic and cell-to-cell water transport pathways. The ability of AM plants to switch between water transport pathways could allow a higher flexibility in the response of these plants to water shortage according to the demand from the shoot.

Colwellia and sulfur-oxidizing bacteria: An unusual dual symbiosis in a Terua mussel (Mytilidae: Bathymodiolinae) from whale falls in the Antilles arc

NASA Astrophysics Data System (ADS)

Duperron, Sébastien; Gros, Olivier

2016-09-01

Seven individuals of a single morphotype of mussels (Bivalvia: Mytilidae) were found attached to a naturally sunken whale intervertebral disk collected in Guadeloupe (Caribbean) at 800 m depth. These specimens resemble small Idas mussels which are found worldwide at cold seeps and hydrothermal vents, and typically harbor ectosymbiotic bacteria on their gills upon which they depend for nutrition. Based on multi-locus gene sequencing, these specimens appear to belong to a new species closely related to two species now included within the genus Terua. Unexpectedly, its closest relatives are found in the Pacific, questioning how this species has reached the Antilles arc. Based on marker gene sequence analysis, electron and fluorescence microscopy, Terua n. sp. harbors two distinct and abundant extracellular bacterial symbionts located between microvilli at the apical surface of host gill epithelial cells. One is a sulfur-oxidizing bacterium similar to the symbionts previously identified in several deep-sea mussels, while the other is related to Colwellia species, a group of cold-adapted heterotrophic bacteria able to degrade organic compounds. This study provides the first evidence for the existence of a dual symbiosis in mussels from whale fall ecosystems in the Caribbean. The evolutionary history of Terua n. sp. and potential role of its Colwellia symbionts are discussed.

On-farm production and utilization of mycorrhizal fungus inoculum

USDA-ARS?s Scientific Manuscript database

Arbuscular mycorrhizal fungi are naturally occurring soil fungi that form a symbiosis with the roots of most crop plants. Among the benefits plants receive from the symbiosis are enhanced nutrient uptake, water relations, and disease resistance. Farmers can better take advantage of the symbiosis e...

Nitrogen recycling through the gut and the nitrogen economy of ruminants: an asynchronous symbiosis.

PubMed

Reynolds, C K; Kristensen, N B

2008-04-01

a daily basis. This may reflect benefits of Orn cycle adaptations and sustained recycling of urea to the gut. The microbial symbiosis of the ruminant is inherently adaptable to asynchronous N and energy supply. Recycling of urea to the gut buffers the effect of irregular dietary N supply such that intuitive benefits of rumen synchrony in terms of the efficiency of N utilization are typically not observed in practice.

Methods for assessing the energy-saving efficiency of industrial symbiosis in industrial parks.

PubMed

Li, Wenfeng; Cui, Zhaojie; Han, Feng

2015-01-01

The available energy resources are being depleted worldwide. Industrial symbiosis (IS) provides a promising approach for increasing the efficiency of energy utilization, with numerous studies reporting the superiority of this technology. However, studies quantifying the energy-saving efficiency of IS remain insufficient. This paper proposes an index system for the quantitative evaluation of the energy-saving efficiency of IS. Both energy-saving and financial indexes were selected, the former include the IS energy-saving index, the contribution rate of energy saved through IS, fractional energy savings, and cut rate of energy consumption per total output value; and the latter include the IS investment payback period, IS input-output ratio, net present value (NPV), and internal rate of return (IRR) of IS. The proposed methods were applied to a case study on the XF Industrial Park (XF IP), in the city of Liaocheng in Shandong Province of China. Three energy-saving channels using IS were found in the XF IP: (a) utilizing the energy of high-temperature materials among industrial processes, (b) recovering waste heat and steam between different processes, and (c) saving energy by sharing infrastructures. The results showed that the energy efficiency index of IS was 0.326, accounting for 34.6% of the comprehensive energy-saving index in 2011, and the fractional energy-savings were 12.42%. The index of energy consumption per total industrial output value varied from 90.9 tce/MRMB to 51.6 tce/MRMB. Thus, the cut rate of energy consumption per total industrial output value was 43.42%. The average values of the IS input-output ratio was 406.2 RMB/tce, 57.2% lower than the price of standard coal. Static investment payback period in the XF IP was 8.5 months, indicating that the XF IP began to earn profit 8.5 months after the construction of all IS modes. The NVP and IRR of each IS mode in the XF IP were greater than zero, with average values equal to 1,789.96 MRMB and 140

Metabolic analysis of Chlorobium chlorochromatii CaD3 reveals clues of the symbiosis in ‘Chlorochromatium aggregatum'.

PubMed Central

Cerqueda-García, Daniel; Martínez-Castilla, León P; Falcón, Luisa I; Delaye, Luis

2014-01-01

A symbiotic association occurs in ‘Chlorochromatium aggregatum', a phototrophic consortium integrated by two species of phylogenetically distant bacteria composed by the green-sulfur Chlorobium chlorochromatii CaD3 epibiont that surrounds a central β-proteobacterium. The non-motile chlorobia can perform nitrogen and carbon fixation, using sulfide as electron donors for anoxygenic photosynthesis. The consortium can move due to the flagella present in the central β-protobacterium. Although Chl. chlorochromatii CaD3 is never found as free-living bacteria in nature, previous transcriptomic and proteomic studies have revealed that there are differential transcription patterns between the symbiotic and free-living status of Chl. chlorocromatii CaD3 when grown in laboratory conditions. The differences occur mainly in genes encoding the enzymatic reactions involved in nitrogen and amino acid metabolism. We performed a metabolic reconstruction of Chl. chlorochromatii CaD3 and an in silico analysis of its amino acid metabolism using an elementary flux modes approach (EFM). Our study suggests that in symbiosis, Chl. chlorochromatii CaD3 is under limited nitrogen conditions where the GS/GOGAT (glutamine synthetase/glutamate synthetase) pathway is actively assimilating ammonia obtained via N2 fixation. In contrast, when free-living, Chl. chlorochromatii CaD3 is in a condition of nitrogen excess and ammonia is assimilated by the alanine dehydrogenase (AlaDH) pathway. We postulate that ‘Chlorochromatium aggregatum' originated from a parasitic interaction where the N2 fixation capacity of the chlorobia would be enhanced by injection of 2-oxoglutarate from the β-proteobacterium via the periplasm. This consortium would have the advantage of motility, which is fundamental to a phototrophic bacterium, and the syntrophy of nitrogen and carbon sources. PMID:24285361

Integrating models to investigate critical phenological overlaps in complex ecological interactions: the mountain pine beetle-fungus symbiosis.

PubMed

Addison, Audrey; Powell, James A; Bentz, Barbara J; Six, Diana L

2015-03-07

The fates of individual species are often tied to synchronization of phenology, however, few methods have been developed for integrating phenological models involving linked species. In this paper, we focus on mountain pine beetle (MPB, Dendroctonus ponderosae) and its two obligate mutualistic fungi, Grosmannia clavigera and Ophiostoma montium. Growth rates of all three partners are driven by temperature, and their idiosyncratic responses affect interactions at important life stage junctures. One critical phase for MPB-fungus symbiosis occurs just before dispersal of teneral (new) adult beetles, when fungi are acquired and transported in specialized structures (mycangia). Before dispersal, fungi must capture sufficient spatial resources within the tree to ensure contact with teneral adults and get packed into mycangia. Mycangial packing occurs at an unknown time during teneral feeding. We adapt thermal models predicting fungal growth and beetle development to predict overlap between the competing fungi and MPB teneral adult feeding windows and emergence. We consider a spectrum of mycangial packing strategies and describe them in terms of explicit functions with unknown parameters. Rates of growth are fixed by laboratory data, the unknown parameters describing various packing strategies, as well as the degree to which mycangial growth is slowed in woody tissues as compared to agar, are determined by maximum likelihood and two years of field observations. At the field location used, the most likely fungus acquisition strategy for MPB was packing mycangia just prior to emergence. Estimated model parameters suggested large differences in the relative growth rates of the two fungi in trees at the study site, with the most likely model estimating that G. clavigera grew approximately twenty-five times faster than O. montium under the bark, which is completely unexpected in comparison with observed fungal growth on agar. Copyright © 2014 Elsevier Ltd. All rights reserved.

Adaptive response of arbuscular mycorrhizal symbiosis to accumulation of elements and translocation in Phragmites australis affected by cadmium stress.

PubMed

Huang, Xiaochen; Ho, Shih-Hsin; Zhu, Shishu; Ma, Fang; Wu, Jieting; Yang, Jixian; Wang, Li

2017-07-15

Arbuscular mycorrhizal (AM) fungi have been reported to play a central role in improving plant tolerance to cadmium (Cd)-contaminated sites. This is achieved by enhancing both the growth of host plants and the nutritive elements in plants. This study assessed potential regulatory effects of AM symbiosis with regard to nutrient uptake and transport, and revealed different response strategies to various Cd concentrations. Phragmites australis was inoculated with Rhizophagus irregularis in the greenhouse cultivation system, where it was treated with 0-20 mg L -1 of Cd for 21days to investigate growth parameters, as well as Cd and nutritive element distribution in response to AM fungus inoculation. Mycorrhizal plants showed a higher tolerance, particularly under high Cd-level stress in the substrate. Moreover, our results determined the roots as dominant Cd reservoirs in plants. The AM fungus improved Cd accumulation and saturated concentration in the roots, thus inhibiting Cd uptake to shoots. The observed distributions of nutritive elements and the interactions among these indicated the highest microelement contribution to roots, Ca contributed maximally in leaves, and K and P contributed similarly under Cd stress. In addition, AM fungus inoculation effectively impacted Mn and P uptake and accumulation while coping with Cd toxicity. This study also demonstrated translocation factor from metal concentration (TF) could be a good parameter to evaluate different transportation strategies induced by various Cd stresses in contrast to the bioconcentration factor (BCF) and translocation factor from metal accumulation (TF'). Copyright © 2017 Elsevier Ltd. All rights reserved.

Mycorrhizal symbiosis effects on growth of chalk false-brome (Brachypodium pinnatum) are dependent on the environmental light regime.

PubMed

Füzy, Anna; Bothe, Hermann; Molnár, Edit; Biró, Borbála

2014-03-01

AMF (arbuscular mycorrhizal fungi) colonization of the grass chalk false-brome (Brachypodium pinnatum (L.) P. B.) was studied in selected habitats under spatially different light regimes: (a) shade condition under oak trees, (b) half shade in a shrubby area and (c) full-sun conditions on unshaded grassland. This study assessed the variations in AMF colonization of the grass dependent on the light supply in field habitats. Soil, root and shoot samples were collected four times during the vegetation period (in June, July, September and October). Root colonization, root and shoot biomass as well as soil water content were determined. The highest rate of AMF colonization was detected in June under half-sun and full-sun conditions, where about 50% of the roots were colonized. The average amount of arbuscules was less than 20% in the roots at the three sites, with the highest number of arbuscules in June, under half-sun and full-sun conditions, however, not under the trees. Overall, best mycorrhizal colonization occurred during summer, and its rate decreased in autumn. This tendency inversely correlated with the amount of precipitation, and thus with the water content of soils. The high colonization rate of the examined root samples, and also its seasonal fluctuation, might reflect the importance of the symbiosis where inorganic nutrients and water are the growth-limiting factors. The marginal AMF colonization of chalk false-brome under shade conditions indicates that plants do not use AMF under all stress conditions. When low light limits photosynthesis and thus growth of the plants, they dispense with the colonization of AMF in order to save the expenditure of organic carbon. Copyright © 2013 Elsevier GmbH. All rights reserved.

Arbuscular mycorrhizal symbiosis increases relative apoplastic water flow in roots of the host plant under both well-watered and drought stress conditions

PubMed Central

Bárzana, Gloria; Aroca, Ricardo; Paz, José Antonio; Chaumont, François; Martinez-Ballesta, Mari Carmen; Carvajal, Micaela; Ruiz-Lozano, Juan Manuel

2012-01-01

Background and Aims The movement of water through mycorrhizal fungal tissues and between the fungus and roots is little understood. It has been demonstrated that arbuscular mycorrhizal (AM) symbiosis regulates root hydraulic properties, including root hydraulic conductivity. However, it is not clear whether this effect is due to a regulation of root aquaporins (cell-to-cell pathway) or to enhanced apoplastic water flow. Here we measured the relative contributions of the apoplastic versus the cell-to-cell pathway for water movement in roots of AM and non-AM plants. Methods We used a combination of two experiments using the apoplastic tracer dye light green SF yellowish and sodium azide as an inhibitor of aquaporin activity. Plant water and physiological status, root hydraulic conductivity and apoplastic water flow were measured. Key Results Roots of AM plants enhanced significantly relative apoplastic water flow as compared with non-AM plants and this increase was evident under both well-watered and drought stress conditions. The presence of the AM fungus in the roots of the host plants was able to modulate the switching between apoplastic and cell-to-cell water transport pathways. Conclusions The ability of AM plants to switch between water transport pathways could allow a higher flexibility in the response of these plants to water shortage according to the demand from the shoot. PMID:22294476

An oxidative burst and its attenuation by bacterial peroxidase activity is required for optimal establishment of the Arachis hypogaea-Bradyrhizobium sp. symbiosis.

PubMed

Muñoz, V; Ibáñez, F; Figueredo, M S; Fabra, A

2016-07-01

The main purpose of this study was to determine whether the Arachis hypogaea L. root oxidative burst, produced at early stages of its symbiotic interaction with Bradyrhizobium sp. SEMIA 6144, and the bacterial antioxidant system are required for the successful development of this interaction. Pharmacological approaches were used to reduce both plant oxidative burst and bacterial peroxidase enzyme activity. In plants whose H2 O2 levels were decreased, a low nodule number, a reduction in the proportion of red nodules (%) and an increase in the bacteroid density were found. The symbiotic phenotype of plants inoculated with a Bradyrhizobium sp. SEMIA 6144 culture showing decreased peroxidase activity was also affected, since the biomass production, nodule number and percentage of red nodules in these plants were lower than in plants inoculated with Bradyrhizobium sp. control cultures. We demonstrated for the first time that the oxidative burst triggered at the early events of the symbiotic interaction in peanut, is a prerequisite for the efficient development of root nodules, and that the antioxidant system of bradyrhizobial peanut symbionts, particularly the activity of peroxidases, is counteracting this oxidative burst for the successful establishment of the symbiosis. Our results provide new insights into the mechanisms involved in the development of the symbiotic interaction established in A. hypogaea L. a legume infected in an intercellular way. © 2016 The Society for Applied Microbiology.

Symbiosis.

ERIC Educational Resources Information Center

Bicevskis, Rob

2002-01-01

Exposing today's students to a balance of science and the outside world is critical. The outdoors provides a context for practical applications of science, exposing the relevance of science to everyday life. Outdoor education instills an awareness that the health of the environment is directly coupled with our own health, enabling us to make…

Dissection of Symbiosis and Organ Development by Integrated Transcriptome Analysis of Lotus japonicus Mutant and Wild-Type Plants

PubMed Central

Høgslund, Niels; Radutoiu, Simona; Krusell, Lene; Voroshilova, Vera; Hannah, Matthew A.; Goffard, Nicolas; Sanchez, Diego H.; Lippold, Felix; Ott, Thomas; Sato, Shusei; Tabata, Satoshi; Liboriussen, Poul; Lohmann, Gitte V.; Schauser, Leif; Weiller, Georg F.; Udvardi, Michael K.; Stougaard, Jens

2009-01-01

Genetic analyses of plant symbiotic mutants has led to the identification of key genes involved in Rhizobium-legume communication as well as in development and function of nitrogen fixing root nodules. However, the impact of these genes in coordinating the transcriptional programs of nodule development has only been studied in limited and isolated studies. Here, we present an integrated genome-wide analysis of transcriptome landscapes in Lotus japonicus wild-type and symbiotic mutant plants. Encompassing five different organs, five stages of the sequentially developed determinate Lotus root nodules, and eight mutants impaired at different stages of the symbiotic interaction, our data set integrates an unprecedented combination of organ- or tissue-specific profiles with mutant transcript profiles. In total, 38 different conditions sampled under the same well-defined growth regimes were included. This comprehensive analysis unravelled new and unexpected patterns of transcriptional regulation during symbiosis and organ development. Contrary to expectations, none of the previously characterized nodulins were among the 37 genes specifically expressed in nodules. Another surprise was the extensive transcriptional response in whole root compared to the susceptible root zone where the cellular response is most pronounced. A large number of transcripts predicted to encode transcriptional regulators, receptors and proteins involved in signal transduction, as well as many genes with unknown function, were found to be regulated during nodule organogenesis and rhizobial infection. Combining wild type and mutant profiles of these transcripts demonstrates the activation of a complex genetic program that delineates symbiotic nitrogen fixation. The complete data set was organized into an indexed expression directory that is accessible from a resource database, and here we present selected examples of biological questions that can be addressed with this comprehensive and powerful

Coral color and depth drive symbiosis ecology of Montipora capitata in Kāne`ohe Bay, O`ahu, Hawai`i

NASA Astrophysics Data System (ADS)

Innis, T.; Cunning, R.; Ritson-Williams, R.; Wall, C. B.; Gates, R. D.

2018-06-01

Scleractinian corals form symbioses with diverse photosynthetic dinoflagellates (genus Symbiodinium) that confer varying levels of performance and stress tolerance to their hosts. Variation in thermal stress susceptibility (i.e., bleaching) among conspecific corals is linked to variability in symbiont community composition, yet factors driving heterogeneous symbiont associations within a population are poorly understood. To investigate potential drivers, we characterized Symbiodinium communities in Montipora capitata ( N = 707 colonies) across the biophysical regions, reef types, and depth range of Kāne`ohe Bay (Hawai`i, USA), where this dominant reef-builder associates with Symbiodinium spp. in clade C (C31) and/or D ( S. glynnii), and occurs as brown and orange color morphs. The distribution of these traits was primarily influenced by depth: orange, D-dominated colonies were more prevalent in shallow, high light environments (< 2 m), whereas brown, C-dominated colonies were more prevalent with increasing depth and light attenuation. Though either color morph could be dominated by either symbiont, brown colonies were almost exclusively C-dominated, while orange colonies were more likely to be D-dominated above 4.3 m, and C-dominated below, revealing a significant interaction between color morph and symbiosis ecology. The distribution of orange, D-dominated colonies extended deeper on patch reefs, where light penetrates deeper, compared to the more turbid, fringing reefs, further supporting light as the driver of these patterns. This work reveals that symbiont community variability may arise either from holobiont phenotypic plasticity or differential survival across light gradients, with implications for predicting coral bleaching responses and informing management applications such as selective breeding of robust corals.

The Independent Acquisition of Plant Root Nitrogen-Fixing Symbiosis in Fabids Recruited the Same Genetic Pathway for Nodule Organogenesis

PubMed Central

Svistoonoff, Sergio; Benabdoun, Faiza Meriem; Nambiar-Veetil, Mathish; Imanishi, Leandro; Vaissayre, Virginie; Cesari, Stella; Diagne, Nathalie; Hocher, Valérie; de Billy, Françoise; Bonneau, Jocelyne; Wall, Luis; Ykhlef, Nadia; Rosenberg, Charles; Bogusz, Didier; Franche, Claudine; Gherbi, Hassen

2013-01-01

Only species belonging to the Fabid clade, limited to four classes and ten families of Angiosperms, are able to form nitrogen-fixing root nodule symbioses (RNS) with soil bacteria. This concerns plants of the legume family (Fabaceae) and Parasponia (Cannabaceae) associated with the Gram-negative proteobacteria collectively called rhizobia and actinorhizal plants associated with the Gram-positive actinomycetes of the genus Frankia. Calcium and calmodulin-dependent protein kinase (CCaMK) is a key component of the common signaling pathway leading to both rhizobial and arbuscular mycorrhizal symbioses (AM) and plays a central role in cross-signaling between root nodule organogenesis and infection processes. Here, we show that CCaMK is also needed for successful actinorhiza formation and interaction with AM fungi in the actinorhizal tree Casuarina glauca and is also able to restore both nodulation and AM symbioses in a Medicago truncatula ccamk mutant. Besides, we expressed auto-active CgCCaMK lacking the auto-inhibitory/CaM domain in two actinorhizal species: C. glauca (Casuarinaceae), which develops an intracellular infection pathway, and Discaria trinervis (Rhamnaceae) which is characterized by an ancestral intercellular infection mechanism. In both species, we found induction of nodulation independent of Frankia similar to response to the activation of CCaMK in the rhizobia-legume symbiosis and conclude that the regulation of actinorhiza organogenesis is conserved regardless of the infection mode. It has been suggested that rhizobial and actinorhizal symbioses originated from a common ancestor with several independent evolutionary origins. Our findings are consistent with the recruitment of a similar genetic pathway governing rhizobial and Frankia nodule organogenesis. PMID:23741336

Production of three symbiosis-related fatty acids by Symbiodinium types in clades A-F associated with marine invertebrate larvae

NASA Astrophysics Data System (ADS)

Mies, M.; Chaves-Filho, A. B.; Miyamoto, S.; Güth, A. Z.; Tenório, A. A.; Castro, C. B.; Pires, D. O.; Calderon, E. N.; Sumida, P. Y. G.

2017-12-01

Symbiodinium are dinoflagellates engaged in a mutualistic symbiosis with multiple coral reef taxa. They are divided in nine different clades (A-I), which typically associate with different hosts. However, very little information is available on metabolic differences in Symbiodinium types, especially when associated with metazoan larvae. We tested whether three ω3 fatty acids (stearidonic acid, SDA; docosapentaenoic acid, DPA; and docosahexaenoic acid, DHA) that are typically translocated from Symbiodinium to its host are produced by Symbiodinium types within clades A-F associated with Mussismilia hispida (scleractinian coral), Berghia stephanieae (nudibranch), and Tridacna crocea (giant clam) larvae. We acquired and spawned broodstock for each host, cultured their larvae, and offered Symbiodinium types belonging to clades A-F. Samples were taken during a 72-h window after the offer of Symbiodinium, and fatty acids were extracted and analyzed by gas chromatography. The concentrations of SDA and DPA for all host larvae-dinoflagellate associations were low and variable, without trends. However, M. hispida planula larvae associated with Symbiodinium A1 and C1 had a statistically significant higher amount of DHA. The veliger larvae of B. stephanieae digested the Symbiodinium, and the amount of DHA remained constant throughout the experiment. The veliger larvae of T. crocea associated with Symbiodinium A1 and C1 also presented a higher amount of DHA, although not statistically different from the other types. These results show that Symbiodinium A1 and C1, in the case of M. hispida and T. crocea (which usually harbor strains within clades A and C), may contribute a small amount of DHA to the larvae of these organisms and form a stronger mutualism than other strains.

Symbiosis revisited: phosphorus and acid buffering stimulate N2 fixation but not Sphagnum growth

NASA Astrophysics Data System (ADS)

van den Elzen, Eva; Kox, Martine A. R.; Harpenslager, Sarah F.; Hensgens, Geert; Fritz, Christian; Jetten, Mike S. M.; Ettwig, Katharina F.; Lamers, Leon P. M.

2017-03-01

In pristine Sphagnum-dominated peatlands, (di)nitrogen (N2) fixing (diazotrophic) microbial communities associated with Sphagnum mosses contribute substantially to the total nitrogen input, increasing carbon sequestration. The rates of symbiotic nitrogen fixation reported for Sphagnum peatlands, are, however, highly variable, and experimental work on regulating factors that can mechanistically explain this variation is largely lacking. For two common fen species (Sphagnum palustre and S. squarrosum) from a high nitrogen deposition area (25 kg N ha-1 yr-1), we found that diazotrophic activity (as measured by 15 - 15N2 labeling) was still present at a rate of 40 nmol N gDW-1 h-1. This was surprising, given that nitrogen fixation is a costly process. We tested the effects of phosphorus availability and buffering capacity by bicarbonate-rich water, mimicking a field situation in fens with stronger groundwater or surface water influence, as potential regulators of nitrogen fixation rates and Sphagnum performance. We expected that the addition of phosphorus, being a limiting nutrient, would stimulate both diazotrophic activity and Sphagnum growth. We indeed found that nitrogen fixation rates were doubled. Plant performance, in contrast, did not increase. Raised bicarbonate levels also enhanced nitrogen fixation, but had a strong negative impact on Sphagnum performance. These results explain the higher nitrogen fixation rates reported for minerotrophic and more nutrient-rich peatlands. In addition, nitrogen fixation was found to strongly depend on light, with rates 10 times higher in light conditions suggesting high reliance on phototrophic organisms for carbon. The contrasting effects of phosphorus and bicarbonate on Sphagnum spp. and their diazotrophic communities reveal strong differences in the optimal niche for both partners with respect to conditions and resources. This suggests a trade-off for the symbiosis of nitrogen fixing microorganisms with their Sphagnum

Newly discovered hydrothermal system on the Alarcón Rise, Mexico

NASA Astrophysics Data System (ADS)

Paduan, J. B.; Clague, D. A.; Caress, D. W.; Lundsten, L.; Martin, J. F.; Nieves-Cardoso, C.

2012-12-01

The Alarcón Rise lies at the mouth of the Gulf of California, and is the last segment of the East Pacific Rise before the plate boundary redirects into the gulf. As part of MBARI's expedition to the gulf in 2012, the neovolcanic zone of the entire ridge segment was mapped by MBARI's mapping AUV. 110 potential hydrothermal chimneys were identified in the new high resolution maps, and 70 were visited with the ROV Doc Ricketts, after having been sought in vain without the maps on an expedition in 2003. Two active vent fields were found, and have been named Meyibó and Ja sít from local native languages. They lie 2.5km apart at ~2300m depth, and are associated with a large, young sheet flow 1/3 of the way along the ridge from the south, on the most inflated part of the ridge. The southern field, Meyibó, contains 14 active chimneys (confirmed with ROV observations) nestled in grabens of several highly fractured cones surrounded by the sheet flow, and generally aligned with its discontinuous, 8km-long fissure system. The northern field, Ja sít, is a broad cluster of 8 active chimneys (also confirmed) rising above the sheet flow's channel system, more than 150m from the fissure. The chimneys stand as tall as 18 m. The most vigorous vent "black smoke" (mineral-rich fluid) >300°C and others are bathed in "white smoke". The active chimneys are populated with bacterial mat and dense clumps of Riftia pachyptila with tubes as long as 1.5m. Abundant limpets, Bythograea thermydron and galatheid crabs, and the pink vent fish Thermarces cerberus were on and near the giant tube worms. Alvinellid worms were observed at 2 chimneys. Some cracks in nearby lava flows vented clear fluid and were populated with tubeworms or Calyptogena magnifica clams. Several chimneys exhibited signs of waning activity: dead tubeworms were still attached and only a minor portion of the edifice supported bacterial mat and live tubeworms. Inactive chimneys are more numerous (48 were confirmed with ROV

Strigolactone Levels in Dicot Roots Are Determined by an Ancestral Symbiosis-Regulated Clade of the PHYTOENE SYNTHASE Gene Family

PubMed Central

Stauder, Ron; Welsch, Ralf; Camagna, Maurizio; Kohlen, Wouter; Balcke, Gerd U.; Tissier, Alain; Walter, Michael H.

2018-01-01

Strigolactones (SLs) are apocarotenoid phytohormones synthesized from carotenoid precursors. They are produced most abundantly in roots for exudation into the rhizosphere to cope with mineral nutrient starvation through support of root symbionts. Abscisic acid (ABA) is another apocarotenoid phytohormone synthesized in roots, which is involved in responses to abiotic stress. Typically low carotenoid levels in roots raise the issue of precursor supply for the biosynthesis of these two apocarotenoids in this organ. Increased ABA levels upon abiotic stress in Poaceae roots are known to be supported by a particular isoform of phytoene synthase (PSY), catalyzing the rate-limiting step in carotenogenesis. Here we report on novel PSY3 isogenes from Medicago truncatula (MtPSY3) and Solanum lycopersicum (SlPSY3) strongly expressed exclusively upon root interaction with symbiotic arbuscular mycorrhizal (AM) fungi and moderately in response to phosphate starvation. They belong to a widespread clade of conserved PSYs restricted to dicots (dPSY3) distinct from the Poaceae-PSY3s involved in ABA formation. An ancient origin of dPSY3s and a potential co-evolution with the AM symbiosis is discussed in the context of PSY evolution. Knockdown of MtPSY3 in hairy roots of M. truncatula strongly reduced SL and AM-induced C13 α-ionol/C14 mycorradicin apocarotenoids. Inhibition of the reaction subsequent to phytoene synthesis revealed strongly elevated levels of phytoene indicating induced flux through the carotenoid pathway in roots upon mycorrhization. dPSY3 isogenes are coregulated with upstream isogenes and downstream carotenoid cleavage steps toward SLs (D27, CCD7, CCD8) suggesting a combined carotenoid/apocarotenoid pathway, which provides “just in time”-delivery of precursors for apocarotenoid formation. PMID:29545815

Functional analysis of duplicated Symbiosis Receptor Kinase (SymRK) genes during nodulation and mycorrhizal infection in soybean (Glycine max).

PubMed

Indrasumunar, Arief; Wilde, Julia; Hayashi, Satomi; Li, Dongxue; Gresshoff, Peter M

2015-03-15

Association between legumes and rhizobia results in the formation of root nodules, where symbiotic nitrogen fixation occurs. The early stages of this association involve a complex of signalling events between the host and microsymbiont. Several genes dealing with early signal transduction have been cloned, and one of them encodes the leucine-rich repeat (LRR) receptor kinase (SymRK; also termed NORK). The Symbiosis Receptor Kinase gene is required by legumes to establish a root endosymbiosis with Rhizobium bacteria as well as mycorrhizal fungi. Using degenerate primer and BAC sequencing, we cloned duplicated SymRK homeologues in soybean called GmSymRKα and GmSymRKβ. These duplicated genes have high similarity of nucleotide (96%) and amino acid sequence (95%). Sequence analysis predicted a malectin-like domain within the extracellular domain of both genes. Several putative cis-acting elements were found in promoter regions of GmSymRKα and GmSymRKβ, suggesting a participation in lateral root development, cell division and peribacteroid membrane formation. The mutant of SymRK genes is not available in soybean; therefore, to know the functions of these genes, RNA interference (RNAi) of these duplicated genes was performed. For this purpose, RNAi construct of each gene was generated and introduced into the soybean genome by Agrobacterium rhizogenes-mediated hairy root transformation. RNAi of GmSymRKβ gene resulted in an increased reduction of nodulation and mycorrhizal infection than RNAi of GmSymRKα, suggesting it has the major activity of the duplicated gene pair. The results from the important crop legume soybean confirm the joint phenotypic action of GmSymRK genes in both mycorrhizal and rhizobial infection seen in model legumes. Copyright © 2015 Elsevier GmbH. All rights reserved.

A Functional Approach towards Understanding the Role of the Mitochondrial Respiratory Chain in an Endomycorrhizal Symbiosis

PubMed Central

Mercy, Louis; Lucic-Mercy, Eva; Nogales, Amaia; Poghosyan, Areg; Schneider, Carolin; Arnholdt-Schmitt, Birgit

2017-01-01

Arbuscular mycorrhizal fungi (AMF) are crucial components of fertile soils, able to provide several ecosystem services for crop production. Current economic, social and legislative contexts should drive the so-called “second green revolution” by better exploiting these beneficial microorganisms. Many challenges still need to be overcome to better understand the mycorrhizal symbiosis, among which (i) the biotrophic nature of AMF, constraining their production, while (ii) phosphate acts as a limiting factor for the optimal mycorrhizal inoculum application and effectiveness. Organism fitness and adaptation to the changing environment can be driven by the modulation of mitochondrial respiratory chain, strongly connected to the phosphorus processing. Nevertheless, the role of the respiratory function in mycorrhiza remains largely unexplored. We hypothesized that the two mitochondrial respiratory chain components, alternative oxidase (AOX) and cytochrome oxidase (COX), are involved in specific mycorrhizal behavior. For this, a complex approach was developed. At the pre-symbiotic phase (axenic conditions), we studied phenotypic responses of Rhizoglomus irregulare spores with two AOX and COX inhibitors [respectively, salicylhydroxamic acid (SHAM) and potassium cyanide (KCN)] and two growth regulators (abscisic acid – ABA and gibberellic acid – Ga3). At the symbiotic phase, we analyzed phenotypic and transcriptomic (genes involved in respiration, transport, and fermentation) responses in Solanum tuberosum/Rhizoglomus irregulare biosystem (glasshouse conditions): we monitored the effects driven by ABA, and explored the modulations induced by SHAM and KCN under five phosphorus concentrations. KCN and SHAM inhibited in vitro spore germination while ABA and Ga3 induced differential spore germination and hyphal patterns. ABA promoted mycorrhizal colonization, strong arbuscule intensity and positive mycorrhizal growth dependency (MGD). In ABA treated plants, R. irregulare

Influence of arbuscular mycorrhizae on biomass production and nitrogen fixation of berseem clover plants subjected to water stress.

PubMed

Saia, Sergio; Amato, Gaetano; Frenda, Alfonso Salvatore; Giambalvo, Dario; Ruisi, Paolo

2014-01-01

Several studies, performed mainly in pots, have shown that arbuscular mycorrhizal symbiosis can mitigate the negative effects of water stress on plant growth. No information is available about the effects of arbuscular mycorrhizal symbiosis on berseem clover growth and nitrogen (N) fixation under conditions of water shortage. A field experiment was conducted in a hilly area of inner Sicily, Italy, to determine whether symbiosis with AM fungi can mitigate the detrimental effects of drought stress (which in the Mediterranean often occurs during the late period of the growing season) on forage yield and symbiotic N2 fixation of berseem clover. Soil was either left under water stress (i.e., rain-fed conditions) or the crop was well-watered. Mycorrhization treatments consisted of inoculation of berseem clover seeds with arbuscular mycorrhizal spores or suppression of arbuscular mycorrhizal symbiosis by means of fungicide treatments. Nitrogen biological fixation was assessed using the 15N-isotope dilution technique. Arbuscular mycorrhizal symbiosis was able to mitigate the negative effect of water stress on berseem clover grown in a typical semiarid Mediterranean environment. In fact, under water stress conditions, arbuscular mycorrhizal symbiosis resulted in increases in total biomass, N content, and N fixation, whereas no effect of crop mycorrhization was observed in the well-watered treatment.

Symbiosis within Symbiosis: Evolving Nitrogen-Fixing Legume Symbionts.

PubMed

Remigi, Philippe; Zhu, Jun; Young, J Peter W; Masson-Boivin, Catherine

2016-01-01

Bacterial accessory genes are genomic symbionts with an evolutionary history and future that is different from that of their hosts. Packages of accessory genes move from strain to strain and confer important adaptations, such as interaction with eukaryotes. The ability to fix nitrogen with legumes is a remarkable example of a complex trait spread by horizontal transfer of a few key symbiotic genes, converting soil bacteria into legume symbionts. Rhizobia belong to hundreds of species restricted to a dozen genera of the Alphaproteobacteria and Betaproteobacteria, suggesting infrequent successful transfer between genera but frequent successful transfer within genera. Here we review the genetic and environmental conditions and selective forces that have shaped evolution of this complex symbiotic trait. Copyright © 2015 Elsevier Ltd. All rights reserved.

Recombination and horizontal transfer of nodulation and ACC deaminase (acdS) genes within Alpha- and Betaproteobacteria nodulating legumes of the Cape Fynbos biome.

PubMed

Lemaire, Benny; Van Cauwenberghe, Jannick; Chimphango, Samson; Stirton, Charles; Honnay, Olivier; Smets, Erik; Muasya, A Muthama

2015-11-01

The goal of this work is to study the evolution and the degree of horizontal gene transfer (HGT) within rhizobial genera of both Alphaproteobacteria (Mesorhizobium, Rhizobium) and Betaproteobacteria (Burkholderia), originating from South African Fynbos legumes. By using a phylogenetic approach and comparing multiple chromosomal and symbiosis genes, we revealed conclusive evidence of high degrees of horizontal transfer of nodulation genes among closely related species of both groups of rhizobia, but also among species with distant genetic backgrounds (Rhizobium and Mesorhizobium), underscoring the importance of lateral transfer of symbiosis traits as an important evolutionary force among rhizobia of the Cape Fynbos biome. The extensive exchange of symbiosis genes in the Fynbos is in contrast with a lack of significant events of HGT among Burkholderia symbionts from the South American Cerrado and Caatinga biome. Furthermore, homologous recombination among selected housekeeping genes had a substantial impact on sequence evolution within Burkholderia and Mesorhizobium. Finally, phylogenetic analyses of the non-symbiosis acdS gene in Mesorhizobium, a gene often located on symbiosis islands, revealed distinct relationships compared to the chromosomal and symbiosis genes, suggesting a different evolutionary history and independent events of gene transfer. The observed events of HGT and incongruence between different genes necessitate caution in interpreting topologies from individual data types. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Investigating kleptothermy: a reptile-seabird association with thermal benefits.

PubMed

Corkery, Ilse; Bell, Ben D; Nelson, Nicola J

2014-01-01

Studies on interspecific interactions between vertebrates based on thermal benefits are poorly represented in the literature. Ecologists know little about a category of thermoregulation termed kleptothermy. We provide evidence that a close association between a medium-sized reptile (tuatara, Sphenodon punctatus) and a small seabird (fairy prion, Pachyptila turtur) enables the reptile to maintain higher-than-average body temperatures. This is the first multiyear data set to reveal that the presence of an endotherm within a burrow has direct, transferable thermal benefits to an ectotherm. It is possible that such positive interspecific interactions may alleviate thermal stress across the range of a single species. Currently, we know little about the evolutionary consequences of such interactions, and future work should focus on whether these thermal benefits increase fitness through increased growth rates or reproductive output.

Protein cages and synthetic polymers: a fruitful symbiosis for drug delivery applications, bionanotechnology and materials science.

PubMed

Rother, Martin; Nussbaumer, Martin G; Renggli, Kasper; Bruns, Nico

2016-11-07

materials, by forming two- and three-dimensional crystals of protein cages and dendrimers, by adsorbing proteins to the surface of materials, by layer-by-layer deposition of proteins and polyelectrolytes and by encapsulating polymers into protein cages. The application of these hybrid materials in the biomedical context or as tools and building blocks for bionanotechnology, biosensing, memory devices and the synthesis of materials will be highlighted. The review aims to showcase recent developments in this field and to suggest possible future directions and opportunities for the symbiosis of protein cages and polymers.

Plant 9-lox oxylipin metabolism in response to arbuscular mycorrhiza

PubMed Central

León Morcillo, Rafael Jorge; Ocampo, Juan A.; García Garrido, José M.

2012-01-01

The establishment of an Arbuscular Mycorrhizal symbiotic interaction (MA) is a successful strategy to substantially promote plant growth, development and fitness. Numerous studies have supported the hypothesis that plant hormones play an important role in the recognition and establishment of symbiosis. Particular attention has been devoted to jasmonic acid (JA) and its derivates, the jasmonates, which are believed to play a major role in AM symbiosis. Jasmonates belong to a diverse class of lipid metabolites known as oxylipins that include other biologically active molecules. Recent transcriptional analyses revealed upregulation of the oxylipin pathway during AM symbiosis in mycorrhizal tomato roots and point a key regulatory feature for oxylipins during AM symbiosis in tomato, particularly these derived from the action of 9-lipoxygenases (9-LOX). In this mini-review we highlight recent progress understanding the function of oxylipins in the establishment of the AM symbiosis and hypothesize that the activation of the 9-LOX pathway might be part of the activation of host defense responses which will then contribute to both, the control of AM fungal spread and the increased resistance to fungal pathogens in mycorrhizal plants. PMID:23073021

Reduced mycorrhizal colonization (rmc) tomato mutant lacks expression of SymRK signaling pathway genes

PubMed Central

Nair, Aswathy; Bhargava, Sujata

2012-01-01

Comparison of the expression of 13 genes involved in arbuscular mycorrhizal (AM) symbiosis was performed in a wild type tomato (Solanum lycopersicum cv 76R) and its reduced mycorrhizal colonization mutant rmc in response to colonization with Glomus fasiculatum. Four defense-related genes were induced to a similar extent in the mutant and wild type AM colonized plants, indicating a systemic response to AM colonization. Genes related to nutrient exchange between the symbiont partners showed higher expression in the AM roots of wild type plants than the mutant plants, which correlated with their arbuscular frequency. A symbiosis receptor kinase that is involved in both nodulation and AM symbiosis was not expressed in the rmc mutant. The fact that some colonization was observed in rmc was suggestive of the existence of an alternate colonization signaling pathway for AM symbiosis in this mutant. PMID:23221680

Ecophysiological responses of tall fescue genotypes to fungal endophyte infection and elevated temperature and precipitation

USDA-ARS?s Scientific Manuscript database

Tall fescue (Schedonorus arundinaceus) can form a symbiosis with the fungal endophyte, Epichloë coenophiala, whose presence can benefit the plant, depending on plant and fungal genetics and prevailing environmental conditions. Despite this symbiosis having agricultural, economic and ecological impor...

Tyrosine pathway regulation is host-mediated in the pea aphid symbiosis during late embryonic and early larval development.

PubMed

Rabatel, Andréane; Febvay, Gérard; Gaget, Karen; Duport, Gabrielle; Baa-Puyoulet, Patrice; Sapountzis, Panagiotis; Bendridi, Nadia; Rey, Marjolaine; Rahbé, Yvan; Charles, Hubert; Calevro, Federica; Colella, Stefano

2013-04-10

Nutritional symbioses play a central role in insects' adaptation to specialized diets and in their evolutionary success. The obligatory symbiosis between the pea aphid, Acyrthosiphon pisum, and the bacterium, Buchnera aphidicola, is no exception as it enables this important agricultural pest insect to develop on a diet exclusively based on plant phloem sap. The symbiotic bacteria provide the host with essential amino acids lacking in its diet but necessary for the rapid embryonic growth seen in the parthenogenetic viviparous reproduction of aphids. The aphid furnishes, in exchange, non-essential amino acids and other important metabolites. Understanding the regulations acting on this integrated metabolic system during the development of this insect is essential in elucidating aphid biology. We used a microarray-based approach to analyse gene expression in the late embryonic and the early larval stages of the pea aphid, characterizing, for the first time, the transcriptional profiles in these developmental phases. Our analyses allowed us to identify key genes in the phenylalanine, tyrosine and dopamine pathways and we identified ACYPI004243, one of the four genes encoding for the aspartate transaminase (E.C. 2.6.1.1), as specifically regulated during development. Indeed, the tyrosine biosynthetic pathway is crucial for the symbiotic metabolism as it is shared between the two partners, all the precursors being produced by B. aphidicola. Our microarray data are supported by HPLC amino acid analyses demonstrating an accumulation of tyrosine at the same developmental stages, with an up-regulation of the tyrosine biosynthetic genes. Tyrosine is also essential for the synthesis of cuticular proteins and it is an important precursor for cuticle maturation: together with the up-regulation of tyrosine biosynthesis, we observed an up-regulation of cuticular genes expression. We were also able to identify some amino acid transporter genes which are essential for the switch

Take advantage of mycorrhizal fungi for improved soil fertility and plant health

USDA-ARS?s Scientific Manuscript database

Arbuscular mycorrhizal [AM] fungi are naturally-occurring soil fungi that form a beneficial symbiosis with the roots of most crops. The plants benefit because the symbiosis increases mineral nutrient uptake, drought resistance, and disease resistance. These characteristics make utilization of AM f...

Elucidating differences in gene expression of Epichloe coenophiala endophytic fungus in reproductive vs. vegetative tissues of tall fescue (Lolium arundinaceum)

USDA-ARS?s Scientific Manuscript database

The tall fescue – Epichloe coenophiala symbiotic system is the most extensively studied of any grass-microbe symbiosis, mainly because of its economic importance worldwide. This is also an extraordinarily stable and mutualistic symbiosis where the endophyte colonizes both vegetative and reproductive...

On-farm production and utilization of arbusclar mycorrhizal fungus inoculum

USDA-ARS?s Scientific Manuscript database

Arbuscular mycorrhizal [AM] fungi are naturally occuring soil fungi that form a mutualistic symbiosis with the majority of crop plants. Among the benefits to the plant that are accredited to living in this symbiosis are: increased mineral nutrient uptake, drought resistance, and disease resistance....

Nuclear-Localized and Deregulated Calcium- and Calmodulin-Dependent Protein Kinase Activates Rhizobial and Mycorrhizal Responses in Lotus japonicus[W

PubMed Central

Takeda, Naoya; Maekawa, Takaki; Hayashi, Makoto

2012-01-01

The common symbiosis pathway is at the core of symbiosis signaling between plants and soil microbes. In this pathway, calcium- and calmodulin-dependent protein kinase (CCaMK) plays a crucial role in integrating the signals both in arbuscular mycorrhizal symbiosis (AMS) and in root nodule symbiosis (RNS). However, the molecular mechanism by which CCaMK coordinates AMS and RNS is largely unknown. Here, we report that the gain-of-function (GOF) variants of CCaMK without the regulatory domains activate both AMS and RNS signaling pathways in the absence of symbiotic partners. This activation requires nuclear localization of CCaMK. Enforced nuclear localization of the GOF-CCaMK variants by fusion with a canonical nuclear localization signal enhances signaling activity of AMS and RNS. The GOF-CCaMK variant triggers formation of a structure similar to the prepenetration apparatus, which guides infection of arbuscular mycorrhizal fungi to host root cells. In addition, the GOF-CCaMK variants without the regulatory domains partly restore AMS but fail to support rhizobial infection in ccamk mutants. These data indicate that AMS, the more ancient type of symbiosis, can be mainly regulated by the kinase activity of CCaMK, whereas RNS, which evolved more recently, requires complex regulation performed by the regulatory domains of CCaMK. PMID:22337918

On-farm AM fungus inoculum production: a complete how-to on-farm am fungus inoculum production

USDA-ARS?s Scientific Manuscript database

Arbuscular mycorrhizal (AM) fungi are beneficial soil fungi that form a symbiosis with the majority of crop plants. The benefits to the plant include increased nutrient uptake and disease and drought resistance. This makes utilization of the symbiosis a potentially important part in ensuring the s...

Management of soil biota and their properties

USDA-ARS?s Scientific Manuscript database

In natural systems organisms can be structured compartmentally to be, close to other organism for symbiosis, away from other organisms for protection and in proximity to nutrients and water. An example of organism symbiosis is fungi breaking down the macromolecule cellulose into smaller more “diges...

Ontological and Epistemic Claims of Realism and Instrumentalism

ERIC Educational Resources Information Center

Lau, Michael Y.

2005-01-01

This article presents comments on "Realism, Instrumentalism, and Scientific Symbiosis: Psychological Theory as a Search for Truth and the Discovery of Solutions" by John T. Cacioppo, Gun R. Semin and Gary G. Berntson. While Lau admires the authors efforts to negotiate symbiosis with seemingly incommensurate realist and instrumentalist positions in…

Insights into archaeal evolution and symbiosis from the genomes of a nanoarchaeon and its inferred crenarchaeal host from Obsidian Pool, Yellowstone National Park

PubMed Central

2013-01-01

Background A single cultured marine organism, Nanoarchaeum equitans, represents the Nanoarchaeota branch of symbiotic Archaea, with a highly reduced genome and unusual features such as multiple split genes. Results The first terrestrial hyperthermophilic member of the Nanoarchaeota was collected from Obsidian Pool, a thermal feature in Yellowstone National Park, separated by single cell isolation, and sequenced together with its putative host, a Sulfolobales archaeon. Both the new Nanoarchaeota (Nst1) and N. equitans lack most biosynthetic capabilities, and phylogenetic analysis of ribosomal RNA and protein sequences indicates that the two form a deep-branching archaeal lineage. However, the Nst1 genome is more than 20% larger, and encodes a complete gluconeogenesis pathway as well as the full complement of archaeal flagellum proteins. With a larger genome, a smaller repertoire of split protein encoding genes and no split non-contiguous tRNAs, Nst1 appears to have experienced less severe genome reduction than N. equitans. These findings imply that, rather than representing ancestral characters, the extremely compact genomes and multiple split genes of Nanoarchaeota are derived characters associated with their symbiotic or parasitic lifestyle. The inferred host of Nst1 is potentially autotrophic, with a streamlined genome and simplified central and energetic metabolism as compared to other Sulfolobales. Conclusions Comparison of the N. equitans and Nst1 genomes suggests that the marine and terrestrial lineages of Nanoarchaeota share a common ancestor that was already a symbiont of another archaeon. The two distinct Nanoarchaeota-host genomic data sets offer novel insights into the evolution of archaeal symbiosis and parasitism, enabling further studies of the cellular and molecular mechanisms of these relationships. Reviewers This article was reviewed by Patrick Forterre, Bettina Siebers (nominated by Michael Galperin) and Purification Lopez-Garcia PMID:23607440

PGRP-LB homolog acts as a negative modulator of immunity in maintaining the gut-microbe symbiosis of red palm weevil, Rhynchophorus ferrugineus Olivier.

PubMed

Dawadi, Bishnu; Wang, Xinghong; Xiao, Rong; Muhammad, Abrar; Hou, Youming; Shi, Zhanghong

2018-09-01

Many notorious insect pests live in the symbiotic associations with gut microbiota. However, the mechanisms underlying how they host their gut microbiota are unknown. Most gut bacteria can release peptidoglycan (PGN) which is an important antigen to activate the immune response. Therefore, how to keep the appropriate gut immune intensity to host commensals while to efficiently remove enteropathogens is vital for insect health. This study is aimed at elucidating the roles of an amidase PGRP, Rf PGRP-LB, in maintaining the gut-microbe symbiosis of Red palm weevil (RPW), Rhynchophorus ferrugineus Olivier. RfPGRP-LB is a secreted protein containing a typical PGRP domain. The existence of five conservative amino acid residues, being required for amidase activity, showed that RfPGRP-LB is a catalytic protein. Expression analysis revealed abundance of RfPGRP-LB transcripts in gut was dramatically higher than those in other tissues. RfPGRP-LB could be significantly induced against the infection of Escherichia coli. In vitro assays revealed that rRfPGRP-LB impaired the growth of E. coli and agglutinated bacteria cells obviously, suggesting RfPGRP-LB is a pathogen recognition receptor and bactericidal molecule. RfPGRP-LB knockdown reduced the persistence of E. coli in gut and load of indigenous gut microbiota significantly. Furthermore, the community structure of indigenous gut microbiota was also intensively altered by RfPGRP-LB silence. Higher levels of the antimicrobial peptide, attacin, were detected in guts of RfPGRP-LB silenced larvae than controls. Collectively, RfPGRP-LB plays multiple roles in modulating the homeostasis of RPW gut microbiota not only by acting as a negative regulator of mucosal immunity through PGN degradation but also as a bactericidal effector to prevent overgrowth of commensals and persistence of noncommensals. Copyright © 2018 Elsevier Ltd. All rights reserved.

Insights into archaeal evolution and symbiosis from the genomes of a nanoarchaeon and its inferred crenarchaeal host from Obsidian Pool, Yellowstone National Park.

PubMed

Podar, Mircea; Makarova, Kira S; Graham, David E; Wolf, Yuri I; Koonin, Eugene V; Reysenbach, Anna-Louise

2013-04-22

A single cultured marine organism, Nanoarchaeum equitans, represents the Nanoarchaeota branch of symbiotic Archaea, with a highly reduced genome and unusual features such as multiple split genes. The first terrestrial hyperthermophilic member of the Nanoarchaeota was collected from Obsidian Pool, a thermal feature in Yellowstone National Park, separated by single cell isolation, and sequenced together with its putative host, a Sulfolobales archaeon. Both the new Nanoarchaeota (Nst1) and N. equitans lack most biosynthetic capabilities, and phylogenetic analysis of ribosomal RNA and protein sequences indicates that the two form a deep-branching archaeal lineage. However, the Nst1 genome is more than 20% larger, and encodes a complete gluconeogenesis pathway as well as the full complement of archaeal flagellum proteins. With a larger genome, a smaller repertoire of split protein encoding genes and no split non-contiguous tRNAs, Nst1 appears to have experienced less severe genome reduction than N. equitans. These findings imply that, rather than representing ancestral characters, the extremely compact genomes and multiple split genes of Nanoarchaeota are derived characters associated with their symbiotic or parasitic lifestyle. The inferred host of Nst1 is potentially autotrophic, with a streamlined genome and simplified central and energetic metabolism as compared to other Sulfolobales. Comparison of the N. equitans and Nst1 genomes suggests that the marine and terrestrial lineages of Nanoarchaeota share a common ancestor that was already a symbiont of another archaeon. The two distinct Nanoarchaeota-host genomic data sets offer novel insights into the evolution of archaeal symbiosis and parasitism, enabling further studies of the cellular and molecular mechanisms of these relationships. This article was reviewed by Patrick Forterre, Bettina Siebers (nominated by Michael Galperin) and Purification Lopez-Garcia.

Carbon dioxide sensing in an obligate insect-fungus symbiosis: CO2 preferences of leaf-cutting ants to rear their mutualistic fungus.

PubMed

Römer, Daniela; Bollazzi, Martin; Roces, Flavio

2017-01-01

Defense against biotic or abiotic stresses is one of the benefits of living in symbiosis. Leaf-cutting ants, which live in an obligate mutualism with a fungus, attenuate thermal and desiccation stress of their partner through behavioral responses, by choosing suitable places for fungus-rearing across the soil profile. The underground environment also presents hypoxic (low oxygen) and hypercapnic (high carbon dioxide) conditions, which can negatively influence the symbiont. Here, we investigated whether workers of the leaf-cutting ant Acromyrmex lundii use the CO2 concentration as an orientation cue when selecting a place to locate their fungus garden, and whether they show preferences for specific CO2 concentrations. We also evaluated whether levels preferred by workers for fungus-rearing differ from those selected for themselves. In the laboratory, CO2 preferences were assessed in binary choices between chambers with different CO2 concentrations, by quantifying number of workers in each chamber and amount of relocated fungus. Leaf-cutting ants used the CO2 concentration as a spatial cue when selecting places for fungus-rearing. A. lundii preferred intermediate CO2 levels, between 1 and 3%, as they would encounter at soil depths where their nest chambers are located. In addition, workers avoided both atmospheric and high CO2 levels as they would occur outside the nest and at deeper soil layers, respectively. In order to prevent fungus desiccation, however, workers relocated fungus to high CO2 levels, which were otherwise avoided. Workers' CO2 preferences for themselves showed no clear-cut pattern. We suggest that workers avoid both atmospheric and high CO2 concentrations not because they are detrimental for themselves, but because of their consequences for the symbiotic partner. Whether the preferred CO2 concentrations are beneficial for symbiont growth remains to be investigated, as well as whether the observed preferences for fungus-rearing influences the ants

Role of the GRAS transcription factor ATA/RAM1 in the transcriptional reprogramming of arbuscular mycorrhiza in Petunia hybrida.

PubMed

Rich, Mélanie K; Courty, Pierre-Emmanuel; Roux, Christophe; Reinhardt, Didier

2017-08-08

Development of arbuscular mycorrhiza (AM) requires a fundamental reprogramming of root cells for symbiosis. This involves the induction of hundreds of genes in the host. A recently identified GRAS-type transcription factor in Petunia hybrida, ATA/RAM1, is required for the induction of host genes during AM, and for morphogenesis of the fungal endosymbiont. To better understand the role of RAM1 in symbiosis, we set out to identify all genes that depend on activation by RAM1 in mycorrhizal roots. We have carried out a transcript profiling experiment by RNAseq of mycorrhizal plants vs. non-mycorrhizal controls in wild type and ram1 mutants. The results show that the expression of early genes required for AM, such as the strigolactone biosynthetic genes and the common symbiosis signalling genes, is independent of RAM1. In contrast, genes that are involved at later stages of symbiosis, for example for nutrient exchange in cortex cells, require RAM1 for induction. RAM1 itself is highly induced in mycorrhizal roots together with many other transcription factors, in particular GRAS proteins. Since RAM1 has previously been shown to be directly activated by the common symbiosis signalling pathway through CYCLOPS, we conclude that it acts as an early transcriptional switch that induces many AM-related genes, among them genes that are essential for the development of arbuscules, such as STR, STR2, RAM2, and PT4, besides hundreds of additional RAM1-dependent genes the role of which in symbiosis remains to be explored. Taken together, these results indicate that the defect in the morphogenesis of the fungal arbuscules in ram1 mutants may be an indirect consequence of functional defects in the host, which interfere with nutrient exchange and possibly other functions on which the fungus depends.

The Scientific Denial of the Real and the Dialectic of Scientism and Humanism

ERIC Educational Resources Information Center

Ramey, Christopher H.; Chrysikou, Evangelia G.

2005-01-01

This article presents comments on "Realism, Instrumentalism, and Scientific Symbiosis: Psychological Theory as a Search for Truth and the Discovery of Solutions" by John T. Cacioppo, Gun R. Semin and Gary G. Berntson. The appeal for the unification of psychology is in fashion and Cacioppo et al.'s term "symbiosis" connotes a cooperative and…

Field performance of cucurbit and tomato plants infected with a nonpathogenic mutant of Colletotrichum magna (teleomorph: Glomerella magna; Jekins and Winstead)

USGS Publications Warehouse

Redman, R.S.; Roossinck, M.J.; Maher, S.; Rodriguez, R.J.

2002-01-01

Path-1 is a UV-induced non-pathogenic mutant of a virulent Colletotrichum magna isolate that establishes mutualistic symbioses with cucurbit and tomato species. Under laboratory conditions, this mutualism results in plant growth enhancement, drought tolerance, and disease protection against fungal pathogens. This study focuses on the efficacy of this symbiosis and the symbiotic lifestyle expressed by path-1 under field conditions in the absence of disease stress. The effects of colonization by path-1 on fruit yields and growth was measured in field plots with four cucurbit species including four watermelon cultivars, and two tomato cultivars, over four growing seasons. The persistence of the symbiosis, extent of colonization, and path-1 transmission were also assessed. Yields from path-1 infected plants were equivalent to or greater than yields from non-inoculated control plants and path-1 systemically colonized plants throughout each growing season. Path-1 also increased the growth rates of tomato plants and was not transmitted to uncolonized plants. The results indicate that there are no metabolic costs of this symbiosis and the symbiosis is maintained under field conditions.

Mathematical morphology for automated analysis of remotely sensed objects in radar images

NASA Technical Reports Server (NTRS)

Daida, Jason M.; Vesecky, John F.

1991-01-01

A symbiosis of pyramidal segmentation and morphological transmission is described. The pyramidal segmentation portion of the symbiosis has resulted in low (2.6 percent) misclassification error rate for a one-look simulation. Other simulations indicate lower error rates (1.8 percent for a four-look image). The morphological transformation portion has resulted in meaningful partitions with a minimal loss of fractal boundary information. An unpublished version of Thicken, suitable for watersheds transformations of fractal objects, is also presented. It is demonstrated that the proposed symbiosis works with SAR (synthetic aperture radar) images: in this case, a four-look Seasat image of sea ice. It is concluded that the symbiotic forms of both segmentation and morphological transformation seem well suited for unsupervised geophysical analysis.

How effectors promote beneficial interactions.

PubMed

Miwa, Hiroki; Okazaki, Shin

2017-08-01

Beneficial microbes such as rhizobia possess effector proteins that are secreted into the host cytoplasm where they modulate host-signaling pathways. Among these effectors, type 3 secreted effectors (T3Es) of rhizobia play roles in promoting nitrogen-fixing nodule symbiosis, suppressing host defenses and directly activating symbiosis-related processes. Rhizobia use the same strategy as pathogenic bacteria to suppress host defenses such as targeting the MAPK cascade. In addition, rhizobial T3E can promote root nodule symbiosis by directly activating Nod factor signaling, which bypasses Nod factor perception. The various strategies employed by beneficial microbes to promote infection and maintain viability in the host are therefore crucial for plant endosymbiosis. Copyright © 2017 Elsevier Ltd. All rights reserved.

Brain-Computer Symbiosis

PubMed Central

Schalk, Gerwin

2009-01-01

The theoretical groundwork of the 1930’s and 1940’s and the technical advance of computers in the following decades provided the basis for dramatic increases in human efficiency. While computers continue to evolve, and we can still expect increasing benefits from their use, the interface between humans and computers has begun to present a serious impediment to full realization of the potential payoff. This article is about the theoretical and practical possibility that direct communication between the brain and the computer can be used to overcome this impediment by improving or augmenting conventional forms of human communication. It is about the opportunity that the limitations of our body’s input and output capacities can be overcome using direct interaction with the brain, and it discusses the assumptions, possible limitations, and implications of a technology that I anticipate will be a major source of pervasive changes in the coming decades. PMID:18310804

Fungal symbiosis unearthed

Treesearch

Daniel Cullen

2008-01-01

Associations between plant roots and fungi are a feature of many terrestrial ecosystems. The genome sequence of a prominent fungal partner opens new avenues for studying such mycorrhizal interactions....

The Prochloron symbiosis

NASA Technical Reports Server (NTRS)

Pardy, R. L.; Lee, K.; Lewin, R. A.

1984-01-01

Colonies of L. patella were collected from inshore water adjacent to small islets near Babelthaup Island, Republic of Palau, for the purpose of studying Prochloron symbionts. Examination of the algal symbionts after fixing, dehydrating, and embedment in Epon, showed Prochloron's central body to consist of a granular ground substance with a few electron-dense inclusions and to be enclosed by prominent photosynthetic membranes. Also found around the central body were thylakoids in a concentric pattern. After comparing the results with those of former studies, it was suggested that Prochloron morphology is host specific. Finally the network of host tissue extensions that entraps the symbionts was noted as possibly being a site for metabolic exchange.

A novel bioinformatics pipeline to discover genes related to arbuscular mycorrhizal symbiosis based on their evolutionary conservation pattern among higher plants.

PubMed

Favre, Patrick; Bapaume, Laure; Bossolini, Eligio; Delorenzi, Mauro; Falquet, Laurent; Reinhardt, Didier

2014-12-03

Genes involved in arbuscular mycorrhizal (AM) symbiosis have been identified primarily by mutant screens, followed by identification of the mutated genes (forward genetics). In addition, a number of AM-related genes has been identified by their AM-related expression patterns, and their function has subsequently been elucidated by knock-down or knock-out approaches (reverse genetics). However, genes that are members of functionally redundant gene families, or genes that have a vital function and therefore result in lethal mutant phenotypes, are difficult to identify. If such genes are constitutively expressed and therefore escape differential expression analyses, they remain elusive. The goal of this study was to systematically search for AM-related genes with a bioinformatics strategy that is insensitive to these problems. The central element of our approach is based on the fact that many AM-related genes are conserved only among AM-competent species. Our approach involves genome-wide comparisons at the proteome level of AM-competent host species with non-mycorrhizal species. Using a clustering method we first established orthologous/paralogous relationships and subsequently identified protein clusters that contain members only of the AM-competent species. Proteins of these clusters were then analyzed in an extended set of 16 plant species and ranked based on their relatedness among AM-competent monocot and dicot species, relative to non-mycorrhizal species. In addition, we combined the information on the protein-coding sequence with gene expression data and with promoter analysis. As a result we present a list of yet uncharacterized proteins that show a strongly AM-related pattern of sequence conservation, indicating that the respective genes may have been under selection for a function in AM. Among the top candidates are three genes that encode a small family of similar receptor-like kinases that are related to the S-locus receptor kinases involved in sporophytic

Thermoregulation of a temperate reptile in a forested habitat.

PubMed

Corkery, Ilse; Bell, Ben D; Nelson, Nicola J

2018-04-01

A major focus in zoology is to understand the phenotypic responses of animals to environmental variation. This is particularly important when dealing with ectotherms in a thermally heterogenous environment. We measured body temperatures of a free-ranging, medium sized temperate reptile, the tuatara, Sphenodon punctatus, to investigate its thermal opportunities and the degree to which the animal actively regulates its body temperature. We found high variation in body temperature between individuals, but this variation could not be attributed to sex or body size. However, variation among individuals in timing of burrow use did affect body temperature and in one of the years studied tuatara were found to be more effective in their thermoregulation when sharing a burrow with a seabird (Pachyptila turtur). The strength of this study is that it includes both biotic and behavioural components of the thermal environment of a temperate reptile, areas which are often missing from thermal studies that focus on the abiotic aspects. Copyright © 2018 Elsevier GmbH. All rights reserved.

Stingless Bee Larvae Require Fungal Steroid to Pupate.

PubMed

Paludo, Camila R; Menezes, Cristiano; Silva-Junior, Eduardo A; Vollet-Neto, Ayrton; Andrade-Dominguez, Andres; Pishchany, Gleb; Khadempour, Lily; do Nascimento, Fabio S; Currie, Cameron R; Kolter, Roberto; Clardy, Jon; Pupo, Mônica T

2018-01-18

The larval stage of the stingless bee Scaptotrigona depilis must consume a specific brood cell fungus in order to continue development. Here we show that this fungus is a member of the genus Zygosaccharomyces and provides essential steroid precursors to the developing bee. Insect pupation requires ecdysteroid hormones, and as insects cannot synthesize sterols de novo, they must obtain steroids in their diet. Larval in vitro culturing assays demonstrated that consuming ergosterol recapitulates the developmental effects on S. depilis as ingestion of Zygosaccharomyces sp. cells. Thus, we determined the molecular underpinning of this intimate mutualistic symbiosis. Phylogenetic analyses showed that similar cases of bee-Zygosaccharomyces symbiosis may exist. This unprecedented case of bee-fungus symbiosis driven by steroid requirement brings new perspectives regarding pollinator-microbiota interaction and preservation.

Arbuscular mycorrhizal symbiosis alters stomatal conductance of host plants more under drought than under amply watered conditions: a meta-analysis.

PubMed

Augé, Robert M; Toler, Heather D; Saxton, Arnold M

2015-01-01

Stomata regulate rates of carbon assimilation and water loss. Arbuscular mycorrhizal (AM) symbioses often modify stomatal behavior and therefore play pivotal roles in plant productivity. The size of the AM effect on stomatal conductance to water vapor (g s ) has varied widely, has not always been apparent, and is unpredictable. We conducted a meta-analysis of 460 studies to determine the size of the AM effect under ample watering and drought and to examine how experimental conditions have influenced the AM effect. Across all host and symbiont combinations under all soil moisture conditions, AM plants have shown 24 % higher g s than nonmycorrhizal (NM) controls. The promotion of g s has been over twice as great during moderate drought than under amply watered conditions. The AM influence on g s has been even more pronounced under severe drought, with over four times the promotion observed with ample water. Members of the Claroideoglomeraceae, Glomeraceae, and other AM families stimulated g s by about the same average amount. Colonization by native AM fungi has produced the largest promotion. Among single-AM symbionts, Glomus deserticola, Claroideoglomus etunicatum, and Funneliformis mosseae have had the largest average effects on g s across studies. Dicotyledonous hosts, especially legumes, have been slightly more responsive to AM symbiosis than monocotyledonous hosts, and C3 plants have shown over twice the AM-induced promotion of C4 plants. The extent of root colonization is important, with heavily colonized plants showing ×10 the g s promotion of lightly colonized plants. AM promotion of g s has been larger in growth chambers and in the field than in greenhouse studies, almost ×3 as large when plants were grown under high light than low light, and ×2.5 as large in purely mineral soils than in soils having an organic component. When AM plants have been compared with NM controls given NM pot culture, they have shown only half the promotion of g s as NM plants

Interplay of Pathogen-Induced Defense Responses and Symbiotic Establishment in Medicago truncatula

PubMed Central

Chen, Tao; Duan, Liujian; Zhou, Bo; Yu, Haixiang; Zhu, Hui; Cao, Yangrong; Zhang, Zhongming

2017-01-01

Suppression of host innate immunity appears to be required for the establishment of symbiosis between rhizobia and host plants. In this study, we established a system that included a host plant, a bacterial pathogen and a symbiotic rhizobium to study the role of innate immunity during symbiotic interactions. A pathogenic bacterium, Pseudomonas syringae pv. tomato strain DC3000 (Pst DC3000), was shown to cause chlorosis in Medicago truncatula A17. Sinorhizobium meliloti strain Sm2011 (Sm2011) and Pst DC3000 strain alone induced similar defense responses in M. truncatula. However, when co-inoculated, Sm2011 specifically suppressed the defense responses induced by Pst DC3000, such as MAPK activation and ROS production. Inoculation with Sm2011 suppressed the transcription of defense-related genes triggered by Pst DC3000 infection, including the receptor of bacterial flagellin (FLS2), pathogenesis-related protein 10 (PR10), and the transcription factor WRKY33. Interestingly, inoculation with Pst DC3000 specifically inhibited the expression of the symbiosis marker genes nodule inception and nodulation pectate lyase and reduced the numbers of infection threads and nodules on M. truncatula A17 roots, indicating that Pst DC3000 inhibits the establishment of symbiosis in M. truncatula. In addition, defense-related genes, such as MAPK3/6, RbohC, and WRKY33, exhibited a transient increase in their expression in the early stage of symbiosis with Sm2011, but the expression dropped down to normal levels at later symbiotic stages. Our results suggest that plant innate immunity plays an antagonistic role in symbiosis by directly reducing the numbers of infection threads and nodules. PMID:28611764

Soybean seed extracts preferentially express genomic loci of Bradyrhizobium japonicum in the initial interaction with soybean, Glycine max (L.) Merr.

PubMed

Wei, Min; Yokoyama, Tadashi; Minamisawa, Kiwamu; Mitsui, Hisayuki; Itakura, Manabu; Kaneko, Takakazu; Tabata, Satoshi; Saeki, Kazuhiko; Omori, Hirofumi; Tajima, Shigeyuki; Uchiumi, Toshiki; Abe, Mikiko; Ohwada, Takuji

2008-08-01

Initial interaction between rhizobia and legumes actually starts via encounters of both partners in the rhizosphere. In this study, the global expression profiles of Bradyrhizobium japonicum USDA 110 in response to soybean (Glycine max) seed extracts (SSE) and genistein, a major soybean-released isoflavone for nod genes induction of B. japonicum, were compared. SSE induced many genomic loci as compared with genistein (5.0 microM), nevertheless SSE-supplemented medium contained 4.7 microM genistein. SSE markedly induced four predominant genomic regions within a large symbiosis island (681 kb), which include tts genes (type III secretion system) and various nod genes. In addition, SSE-treated cells expressed many genomic loci containing genes for polygalacturonase (cell-wall degradation), exopolysaccharide synthesis, 1-aminocyclopropane-1-carboxylate deaminase, ribosome proteins family and energy metabolism even outside symbiosis island. On the other hand, genistein-treated cells exclusively showed one expression cluster including common nod gene operon within symbiosis island and six expression loci including multidrug resistance, which were shared with SSE-treated cells. Twelve putatively regulated genes were indeed validated by quantitative RT-PCR. Several SSE-induced genomic loci likely participate in the initial interaction with legumes. Thus, these results can provide a basic knowledge for screening novel genes relevant to the B. japonicum- soybean symbiosis.

Photosymbiosis and the expansion of shallow-water corals

PubMed Central

Frankowiak, Katarzyna; Wang, Xingchen T.; Sigman, Daniel M.; Gothmann, Anne M.; Kitahara, Marcelo V.; Mazur, Maciej; Meibom, Anders; Stolarski, Jarosław

2016-01-01

Roughly 240 million years ago (Ma), scleractinian corals rapidly expanded and diversified across shallow marine environments. The main driver behind this evolution is uncertain, but the ecological success of modern reef-building corals is attributed to their nutritional symbiosis with photosynthesizing dinoflagellate algae. We show that a suite of exceptionally preserved Late Triassic (ca. 212 Ma) coral skeletons from Antalya (Turkey) have microstructures, carbonate 13C/12C and 18O/16O, and intracrystalline skeletal organic matter 15N/14N all indicating symbiosis. This includes species with growth forms conventionally considered asymbiotic. The nitrogen isotopes further suggest that their Tethys Sea habitat was a nutrient-poor, low-productivity marine environment in which photosymbiosis would be highly advantageous. Thus, coral-dinoflagellate symbiosis was likely a key driver in the evolution and expansion of shallow-water scleractinians. PMID:27847868

Cryptophyte farming by symbiotic ciliate host detected in situ.

PubMed

Qiu, Dajun; Huang, Liangmin; Lin, Senjie

2016-10-25

Protist-alga symbiosis is widespread in the ocean, but its characteristics and function in situ remain largely unexplored. Here we report the symbiosis of the ciliate Mesodinium rubrum with cryptophyte cells during a red-tide bloom in Long Island Sound. In contrast to the current notion that Mesodinium retains cryptophyte chloroplasts or organelles, our multiapproach analyses reveal that in this bloom the endosymbiotic Teleaulax amphioxeia cells were intact and expressing genes of membrane transporters, nucleus-to-cytoplasm RNA transporters, and all major metabolic pathways. Among the most highly expressed were ammonium transporters in both organisms, indicating cooperative acquisition of ammonium as a major N nutrient, and genes for photosynthesis and cell division in the cryptophyte, showing active population proliferation of the endosymbiont. We posit this as a "Mesodinium-farming-Teleaulax" relationship, a model of protist-alga symbiosis worth further investigation by metatranscriptomic technology.

Important Late-Stage Symbiotic Role of the Sinorhizobium meliloti Exopolysaccharide Succinoglycan.

PubMed

Arnold, Markus F F; Penterman, Jon; Shabab, Mohammed; Chen, Esther J; Walker, Graham C

2018-07-01

Sinorhizobium meliloti enters into beneficial symbiotic interactions with Medicago species of legumes. Bacterial exopolysaccharides play critical signaling roles in infection thread initiation and growth during the early stages of root nodule formation. After endocytosis of S. meliloti by plant cells in the developing nodule, plant-derived nodule-specific cysteine-rich (NCR) peptides mediate terminal differentiation of the bacteria into nitrogen-fixing bacteroids. Previous transcriptional studies showed that the intensively studied cationic peptide NCR247 induces expression of the exo genes that encode the proteins required for succinoglycan biosynthesis. In addition, genetic studies have shown that some exo mutants exhibit increased sensitivity to the antimicrobial action of NCR247. Therefore, we investigated whether the symbiotically active S. meliloti exopolysaccharide succinoglycan can protect S. meliloti against the antimicrobial activity of NCR247. We discovered that high-molecular-weight forms of succinoglycan have the ability to protect S. meliloti from the antimicrobial action of the NCR247 peptide but low-molecular-weight forms of wild-type succinoglycan do not. The protective function of high-molecular-weight succinoglycan occurs via direct molecular interactions between anionic succinoglycan and the cationic NCR247 peptide, but this interaction is not chiral. Taken together, our observations suggest that S. meliloti exopolysaccharides not only may be critical during early stages of nodule invasion but also are upregulated at a late stage of symbiosis to protect bacteria against the bactericidal action of cationic NCR peptides. Our findings represent an important step forward in fully understanding the complete set of exopolysaccharide functions during legume symbiosis. IMPORTANCE Symbiotic interactions between rhizobia and legumes are economically important for global food production. The legume symbiosis also is a major part of the global nitrogen

How Many Peas in a Pod? Legume Genes Responsible for Mutualistic Symbioses Underground

PubMed Central

Kouchi, Hiroshi; Imaizumi-Anraku, Haruko; Hayashi, Makoto; Hakoyama, Tsuneo; Nakagawa, Tomomi; Umehara, Yosuke; Suganuma, Norio; Kawaguchi, Masayoshi

2010-01-01

The nitrogen-fixing symbiosis between legume plants and Rhizobium bacteria is the most prominent plant–microbe endosymbiotic system and, together with mycorrhizal fungi, has critical importance in agriculture. The introduction of two model legume species, Lotus japonicus and Medicago truncatula, has enabled us to identify a number of host legume genes required for symbiosis. A total of 26 genes have so far been cloned from various symbiotic mutants of these model legumes, which are involved in recognition of rhizobial nodulation signals, early symbiotic signaling cascades, infection and nodulation processes, and regulation of nitrogen fixation. These accomplishments during the past decade provide important clues to understanding not only the molecular mechanisms underlying plant–microbe endosymbiotic associations but also the evolutionary aspects of nitrogen-fixing symbiosis between legume plants and Rhizobium bacteria. In this review we survey recent progress in molecular genetic studies using these model legumes. PMID:20660226

Genetic and Molecular Mechanisms Underlying Symbiotic Specificity in Legume-Rhizobium Interactions.

PubMed

Wang, Qi; Liu, Jinge; Zhu, Hongyan

2018-01-01

Legumes are able to form a symbiotic relationship with nitrogen-fixing soil bacteria called rhizobia. The result of this symbiosis is to form nodules on the plant root, within which the bacteria can convert atmospheric nitrogen into ammonia that can be used by the plant. Establishment of a successful symbiosis requires the two symbiotic partners to be compatible with each other throughout the process of symbiotic development. However, incompatibility frequently occurs, such that a bacterial strain is unable to nodulate a particular host plant or forms nodules that are incapable of fixing nitrogen. Genetic and molecular mechanisms that regulate symbiotic specificity are diverse, involving a wide range of host and bacterial genes/signals with various modes of action. In this review, we will provide an update on our current knowledge of how the recognition specificity has evolved in the context of symbiosis signaling and plant immunity.

Cryptophyte farming by symbiotic ciliate host detected in situ

PubMed Central

Qiu, Dajun; Huang, Liangmin; Lin, Senjie

2016-01-01

Protist–alga symbiosis is widespread in the ocean, but its characteristics and function in situ remain largely unexplored. Here we report the symbiosis of the ciliate Mesodinium rubrum with cryptophyte cells during a red-tide bloom in Long Island Sound. In contrast to the current notion that Mesodinium retains cryptophyte chloroplasts or organelles, our multiapproach analyses reveal that in this bloom the endosymbiotic Teleaulax amphioxeia cells were intact and expressing genes of membrane transporters, nucleus-to-cytoplasm RNA transporters, and all major metabolic pathways. Among the most highly expressed were ammonium transporters in both organisms, indicating cooperative acquisition of ammonium as a major N nutrient, and genes for photosynthesis and cell division in the cryptophyte, showing active population proliferation of the endosymbiont. We posit this as a “Mesodinium-farming-Teleaulax” relationship, a model of protist–alga symbiosis worth further investigation by metatranscriptomic technology. PMID:27791006

Chromium resistance of dandelion (Taraxacum platypecidum Diels.) and bermudagrass (Cynodon dactylon [Linn.] Pers.) is enhanced by arbuscular mycorrhiza in Cr(VI)-contaminated soils.

PubMed

Wu, Song-Lin; Chen, Bao-Dong; Sun, Yu-Qing; Ren, Bai-Hui; Zhang, Xin; Wang, You-Shan

2014-09-01

In a greenhouse pot experiment, dandelion (Taraxacum platypecidum Diels.) and bermudagrass (Cynodon dactylon[Linn.] Pers.), inoculated with and without arbuscular mycorrhizal fungus (AMF) Rhizophagus irregularis, were grown in chromium (Cr)-amended soils (0 mg/kg, 5 mg/kg, 10 mg/kg, and 20 mg/kg Cr[VI]) to test whether arbuscular mycorrhizal (AM) symbiosis can improve Cr tolerance in different plant species. The experimental results indicated that the dry weights of both plant species were dramatically increased by AM symbiosis. Mycorrhizal colonization increased plant P concentrations and decreased Cr concentrations and Cr translocation from roots to shoots for dandelion; in contrast, mycorrhizal colonization decreased plant Cr concentrations without improvement of P nutrition in bermudagrass. Chromium speciation analysis revealed that AM symbiosis potentially altered Cr species and bioavailability in the rhizosphere. The study confirmed the protective effects of AMF on host plants under Cr contaminations. © 2014 SETAC.

Relationship between luminous fish and symbiosis. I. Comparative studies of lipopolysaccharides isolated from symbiotic luminous bacteria of the luminous marine fish, Physiculus japonicus.

PubMed

Kuwae, T; Andoh, M; Fukasawa, S; Kurata, M

1983-01-01

In order to investigate the relationship between host and symbiosis in the luminous marine fish, Physiculus japonicus, the bacterial lipopolysaccharides (LPS) of symbiotic luminous bacteria were compared serologically and electrophoretically. Five symbiotic luminous bacteria (PJ strains) were separately isolated from five individuals of this fish species caught at three points, off the coasts of Chiba, Nakaminato, and Oharai. LPS preparations were made from these bacteria by Westphal's phenol-water method and highly purified by repeated ultracentrifugation. These LPSs contained little or no 2-keto-3-deoxyoctonate and had powerful mitogenic activity. In sodium dodecylsulfate polyacrylamide gel electrophoresis, these PJ-1 to -5 LPSs were separated by their electrophoretic patterns into three groups; the first group included PJ-1 and PJ-4, the second group PJ-2 and PJ-3, and the third group PJ-5 alone. The results agreed with those of the double immunodiffusion test; precipitin lines completely coalesced within each group but not with other groups. In immunoelectrophoresis, one precipitin line was observed between anti PJ-2 LPS serum and PJ-5 LPS but the electrophoretic mobility of PJ-5 LPS was clearly different from that of the PJ-2 LPS group. Furthermore, in a 50% inhibition test with PJ-2 LPS by the passive hemolysis system, the doses of PJ-2 LPS, PJ-3 LPS, and PJ-5 LPS required for 50% inhibition (ID50) in this system were 0.25, 0.25, and 21.6 micrograms/ml for each alkali-treated LPS, respectively, and the ID50's of both PJ-1 LPS and PJ-4 LPS were above 1,000 micrograms/ml. These results indicate that PJ-5 LPS has an antigenic determinant partially in common with LPS from the PJ-2 group but not with LPS from the PJ-1 group and that the symbiotic luminous bacterium PJ-5 is more closely related to the PJ-2 group than to the PJ-1 group. These results show that the species Physiculus japonicus is symbiotically associated with at least three immunologically different

Symbiotic Association with Mycoplasma hominis Can Influence Growth Rate, ATP Production, Cytolysis and Inflammatory Response of Trichomonas vaginalis

PubMed Central

Margarita, Valentina; Rappelli, Paola; Dessì, Daniele; Pintus, Gianfranco; Hirt, Robert P.; Fiori, Pier L.

2016-01-01

The symbiosis between the parasitic protist Trichomonas vaginalis and the opportunistic bacterium Mycoplasma hominis is the only one currently described involving two obligate human mucosal symbionts with pathogenic capabilities that can cause independent diseases in the same anatomical site: the lower urogenital tract. Although several aspects of this intriguing microbial partnership have been investigated, many questions on the influence of this symbiosis on the parasite pathobiology still remain unanswered. Here, we examined with in vitro cultures how M. hominis could influence the pathobiology of T. vaginalis by investigating the influence of M. hominis on parasite replication rate, haemolytic activity and ATP production. By comparing isogenic mycoplasma-free T. vaginalis and parasites stably associated with M. hominis we could demonstrate that the latter show a higher replication rate, increased haemolytic activity and are able to produce larger amounts of ATP. In addition, we demonstrated in a T. vaginalis-macrophage co-culture system that M. hominis could modulate an aspect of the innate immuno-response to T. vaginalis infections by influencing the production of nitric oxide (NO) by human macrophages, with the parasite-bacteria symbiosis outcompeting the human cells for the key substrate arginine. These results support a model in which the symbiosis between T. vaginalis and M. hominis influences host-microbes interactions to the benefit of both microbial partners during infections and to the detriment of their host. PMID:27379081

Aiptasia sp. larvae as a model to reveal mechanisms of symbiont selection in cnidarians

NASA Astrophysics Data System (ADS)

Wolfowicz, Iliona; Baumgarten, Sebastian; Voss, Philipp A.; Hambleton, Elizabeth A.; Voolstra, Christian R.; Hatta, Masayuki; Guse, Annika

2016-09-01

Symbiosis, defined as the persistent association between two distinct species, is an evolutionary and ecologically critical phenomenon facilitating survival of both partners in diverse habitats. The biodiversity of coral reef ecosystems depends on a functional symbiosis with photosynthetic dinoflagellates of the highly diverse genus Symbiodinium, which reside in coral host cells and continuously support their nutrition. The mechanisms underlying symbiont selection to establish a stable endosymbiosis in non-symbiotic juvenile corals are unclear. Here we show for the first time that symbiont selection patterns for larvae of two Acropora coral species and the model anemone Aiptasia are similar under controlled conditions. We find that Aiptasia larvae distinguish between compatible and incompatible symbionts during uptake into the gastric cavity and phagocytosis. Using RNA-Seq, we identify a set of candidate genes potentially involved in symbiosis establishment. Together, our data complement existing molecular resources to mechanistically dissect symbiont phagocytosis in cnidarians under controlled conditions, thereby strengthening the role of Aiptasia larvae as a powerful model for cnidarian endosymbiosis establishment.

A single evolutionary innovation drives the deep evolution of symbiotic N2-fixation in angiosperms

PubMed Central

Werner, Gijsbert D. A.; Cornwell, William K.; Sprent, Janet I.; Kattge, Jens; Kiers, E. Toby

2014-01-01

Symbiotic associations occur in every habitat on earth, but we know very little about their evolutionary histories. Current models of trait evolution cannot adequately reconstruct the deep history of symbiotic innovation, because they assume homogenous evolutionary processes across millions of years. Here we use a recently developed, heterogeneous and quantitative phylogenetic framework to study the origin of the symbiosis between angiosperms and nitrogen-fixing (N2) bacterial symbionts housed in nodules. We compile the largest database of global nodulating plant species and reconstruct the symbiosis’ evolution. We identify a single, cryptic evolutionary innovation driving symbiotic N2-fixation evolution, followed by multiple gains and losses of the symbiosis, and the subsequent emergence of ‘stable fixers’ (clades extremely unlikely to lose the symbiosis). Originating over 100 MYA, this innovation suggests deep homology in symbiotic N2-fixation. Identifying cryptic innovations on the tree of life is key to understanding the evolution of complex traits, including symbiotic partnerships. PMID:24912610