Analyses between Reproductive Behavior, Genetic Diversity and Pythium Responsiveness in Zingiber spp. Reveal an Adaptive Significance for Hemiclonality

PubMed Central

Thomas, Geethu E.; Geetha, Kiran A.; Augustine, Lesly; Mamiyil, Sabu; Thomas, George

2016-01-01

Mode of reproduction is generally considered to have long-range evolutionary implications on population survival. Because sexual reproduction produces genetically diverse genotypes, this mode of reproduction is predicted to positively influence the success potential of offspring in evolutionary arms race with parasites (Red queen) whereas, without segregation and recombination, the obligate asexual multiplication may push a species into extinction due to the steady accumulation of deleterious mutations (Muller’s ratchet). However, the extent of linearity between reproductive strategies, genetic diversity and population fitness, and the contributions of different breeding strategies to population fitness are yet to be understood clearly. Genus Zingiber belonging to the pan-tropic family Zingiberaceae represents a good system to study contributions of different breeding behavior on genetic diversity and population fitness, as this genus comprises species with contrasting breeding systems. In this study, we analyzed breeding behavior, amplified fragment length polymorphism diversity and response to the soft-rot pathogen Pythium aphanidermatum in 18 natural populations of three wild Zingiber spp.: Z. neesanum, Z. nimmonii, and Z. zerumbet, together with the obligately asexual cultivated congener, ginger (Z. officinale). Ginger showed an exceptionally narrow genetic base, and adding to this, all the tested cultivars were uniformly susceptible to soft-rot. Concordant with the postulates of Muller’s ratchet, the background selection may be continuously pushing ginger into the ancestral state, rendering it inefficient in host-pathogen coevolution. Z. neesanum and Z. nimmonii populations were sexual and genetically diverse; however, contrary to Red Queen expectations, the populations were highly susceptible to soft-rot. Z. zerumbet showed a hemiclonal breeding behavior. The populations inhabiting forest understory were large and continuous, sexual and genetically diverse, but were susceptible, whereas populations inhabiting the revenue land were fragmented and monoclonal, but were resistant. It may be possible that, when genetic recombination becomes at a premium due to the genetic constraints imparted by habitat fragmentation or pathogen pressure, Z. zerumbet PMID:28066470

Genetic variation in Pythium myriotylum based on SNP typing and development of a PCR-RFLP detection of isolates recovered from Pythium soft rot ginger.

PubMed

Le, D P; Smith, M K; Aitken, E A B

2017-10-01

Pythium myriotylum is responsible for severe losses in both capsicum and ginger crops in Australia under different regimes. Intraspecific genomic variation within the pathogen might explain the differences in aggressiveness and pathogenicity on diverse hosts. In this study, whole genome data of four P. myriotylum isolates recovered from three hosts and one Pythium zingiberis isolate were derived and analysed for sequence diversity based on single nucleotide polymorphisms (SNPs). A higher number of true and unique SNPs occurred in P. myriotylum isolates obtained from ginger with symptoms of Pythium soft rot (PSR) in Australia compared to other P. myriotylum isolates. Overall, SNPs were discovered more in the mitochondrial genome than those in the nuclear genome. Among the SNPs, a single substitution from the cytosine (C) to the thymine (T) in the partially sequenced CoxII gene of 14 representatives of PSR P. myriotylum isolates was within a restriction site of HinP1I enzyme which was used in the PCR-RFLP for detection and identification of the isolates without sequencing. The PCR-RFLP was also sensitive to detect PSR P. myriotylum strains from artificially infected ginger without the need for isolation for pure cultures. This is the first study of intraspecific variants of Pythium myriotylum isolates recovered from different hosts and origins based on single nucleotide polymorphism (SNP) genotyping of multiple genes. The SNPs discovered provide valuable makers for detection and identification of P. myriotylum strains initially isolated from Pythium soft rot (PSR) ginger by using PCR-RFLP of the CoxII locus. The PCR-RFLP was also sensitive to detect P. myriotylum directly from PSR ginger sampled from pot trials without the need of isolation for pure cultures. © 2017 The Society for Applied Microbiology.

Systematics of Plant-Pathogenic and Related Streptomyces Species Based on Phylogenetic Analyses of Multiple Gene Loci

USDA-ARS?s Scientific Manuscript database

The 10 species of Streptomyces implicated as the etiological agents in scab disease of potatoes or soft rot disease of sweet potatoes are distributed among 7 different phylogenetic clades in analyses based on 16S rRNA gene sequences, but high sequence similarity of this gene among Streptomyces speci...

Oxygen-Dependent Globin Coupled Sensor Signaling Modulates Motility and Virulence of the Plant Pathogen Pectobacterium carotovorum.

PubMed

Burns, Justin L; Jariwala, Parth B; Rivera, Shannon; Fontaine, Benjamin M; Briggs, Laura; Weinert, Emily E

2017-08-18

Bacterial pathogens utilize numerous signals to identify the presence of their host and coordinate changes in gene expression that allow for infection. Within plant pathogens, these signals typically include small molecules and/or proteins from their plant hosts and bacterial quorum sensing molecules to ensure sufficient bacterial cell density for successful infection. In addition, bacteria use environmental signals to identify conditions when the host defenses are weakened and potentially to signal entry into an appropriate host/niche for infection. A globin coupled sensor protein (GCS), termed PccGCS, within the soft rot bacterium Pectobacterium carotovorum ssp. carotovorum WPP14 has been identified as an O 2 sensor and demonstrated to alter virulence factor excretion and control motility, with deletion of PccGCS resulting in decreased rotting of a potato host. Using small molecules that modulate bacterial growth and quorum sensing, PccGCS signaling also has been shown to modulate quorum sensing pathways, resulting in the PccGCS deletion strain being more sensitive to plant-derived phenolic acids, which can function as quorum sensing inhibitors, and exhibiting increased N-acylhomoserine lactone (AHL) production. These findings highlight a role for GCS proteins in controlling key O 2 -dependent phenotypes of pathogenic bacteria and suggest that modulating GCS signaling to limit P. carotovorum motility may provide a means to decrease rotting of plant hosts.

Phylogeny of pectolytic bacteria associated with recent outbreaks of potato soft rot and blackleg in the United States

USDA-ARS?s Scientific Manuscript database

Soft rot diseases of potato are caused by several species of bacteria belonging to the newly described family Pectobacteriaceae. Multiple species of Pectobacterium are known to cause soft rot diseases during field production and storage of potatoes. Recently, the genus Dickeya has been connected wi...

Biocontrol of the Potato Blackleg and Soft Rot Diseases Caused by Dickeya dianthicola.

PubMed

Raoul des Essarts, Yannick; Cigna, Jérémy; Quêtu-Laurent, Angélique; Caron, Aline; Munier, Euphrasie; Beury-Cirou, Amélie; Hélias, Valérie; Faure, Denis

2016-01-01

Development of protection tools targeting Dickeya species is an important issue in the potato production. Here, we present the identification and the characterization of novel biocontrol agents. Successive screenings of 10,000 bacterial isolates led us to retain 58 strains that exhibited growth inhibition properties against several Dickeya sp. and/or Pectobacterium sp. pathogens. Most of them belonged to the Pseudomonas and Bacillus genera. In vitro assays revealed a fitness decrease of the tested Dickeya sp. and Pectobacterium sp. pathogens in the presence of the biocontrol agents. In addition, four independent greenhouse assays performed to evaluate the biocontrol bacteria effect on potato plants artificially contaminated with Dickeya dianthicola revealed that a mix of three biocontrol agents, namely, Pseudomonas putida PA14H7 and Pseudomonas fluorescens PA3G8 and PA4C2, repeatedly decreased the severity of blackleg symptoms as well as the transmission of D. dianthicola to the tuber progeny. This work highlights the use of a combination of biocontrol strains as a potential strategy to limit the soft rot and blackleg diseases caused by D. dianthicola on potato plants and tubers. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Biocontrol of the Potato Blackleg and Soft Rot Diseases Caused by Dickeya dianthicola

PubMed Central

Raoul des Essarts, Yannick; Cigna, Jérémy; Quêtu-Laurent, Angélique; Caron, Aline; Munier, Euphrasie; Beury-Cirou, Amélie

2015-01-01

Development of protection tools targeting Dickeya species is an important issue in the potato production. Here, we present the identification and the characterization of novel biocontrol agents. Successive screenings of 10,000 bacterial isolates led us to retain 58 strains that exhibited growth inhibition properties against several Dickeya sp. and/or Pectobacterium sp. pathogens. Most of them belonged to the Pseudomonas and Bacillus genera. In vitro assays revealed a fitness decrease of the tested Dickeya sp. and Pectobacterium sp. pathogens in the presence of the biocontrol agents. In addition, four independent greenhouse assays performed to evaluate the biocontrol bacteria effect on potato plants artificially contaminated with Dickeya dianthicola revealed that a mix of three biocontrol agents, namely, Pseudomonas putida PA14H7 and Pseudomonas fluorescens PA3G8 and PA4C2, repeatedly decreased the severity of blackleg symptoms as well as the transmission of D. dianthicola to the tuber progeny. This work highlights the use of a combination of biocontrol strains as a potential strategy to limit the soft rot and blackleg diseases caused by D. dianthicola on potato plants and tubers. PMID:26497457

Effective management of soft rot of ginger caused by Pythium spp. and Fusarium spp.: emerging role of nanotechnology.

PubMed

Rai, Mahendra; Ingle, Avinash P; Paralikar, Priti; Anasane, Netravati; Gade, Rajendra; Ingle, Pramod

2018-06-09

Ginger (Zingiber officinale Rosc.) is a tropical plant cultivated all over the world due to its culinary and medicinal properties. It is one of the most important spices commonly used in food, which increases its commercial value. However, soft rot (rhizome rot) is a common disease of ginger caused by fungi such as Pythium and Fusarium spp. It is the most destructive disease of ginger, which can reduce the production by 50 to 90%. Application of chemical fungicides is considered as an effective method to control soft rot of ginger but extensive use of fungicides pose serious risk to environmental and human health. Therefore, the development of ecofriendly and economically viable alternative approaches for effective management of soft rot of ginger such diseases is essentially required. An acceptable approach that is being actively investigated involves nanotechnology, which can potentially be used to control Pythium and Fusarium. The present review is aimed to discuss worldwide status of soft rot associated with ginger, the traditional methods available for the management of Pythium and Fusarium spp. and most importantly, the role of various nanomaterials in the management of soft rot of ginger. Moreover, possible antifungal mechanisms for chemical fungicides, biological agents and nanoparticles have also been discussed.

Carbohydrate and ethane release with Erwinia carotovora subspecies betavasculorum--induced necrosis.

PubMed

Kuykendall, L David; Hunter, William J

2008-02-01

Erwinia carotovora subspecies betavasculorum, also known as E. betavasculorum and Pectobacterium betavasculorum, is a soil bacterium that has the capacity to cause root rot necrosis of sugarbeets. The qualitatively different pathogenicity exhibited by the virulent E. carotovora strain and two avirulent strains, a Citrobacter sp. and an Enterobacter cloacae, was examined using digital analysis of photographic evidence of necrosis as well as for carbohydrate, ethane, and ethylene release compared with uninoculated potato tuber slices. Visual scoring of necrosis was superior to digital analysis of photographs. The release of carbohydrates and ethane from potato tuber slices inoculated with the soft rot necrosis-causing Erwinia was significantly greater than that of potato tuber slices that had not been inoculated or that had been inoculated with the nonpathogenic E. cloacae and Citrobacter sp. strains. Interestingly, ethylene production from potato slices left uninoculated or inoculated with the nonpathogenic Citrobacter strain was 5- to 10-fold higher than with potato slices inoculated with the pathogenic Erwinia strain. These findings suggest that (1) carbohydrate release might be a useful measure of the degree of pathogenesis, or relative virulence; and that (2) bacterial suppression of ethylene formation may be a critical step in root rot disease formation.

Revised Phylogeny and Novel Horizontally Acquired Virulence Determinants of the Model Soft Rot Phytopathogen Pectobacterium wasabiae SCC3193

PubMed Central

Koskinen, Patrik; Nokso-Koivisto, Jussi; Pasanen, Miia; Broberg, Martin; Plyusnin, Ilja; Törönen, Petri; Holm, Liisa; Pirhonen, Minna; Palva, E. Tapio

2012-01-01

Soft rot disease is economically one of the most devastating bacterial diseases affecting plants worldwide. In this study, we present novel insights into the phylogeny and virulence of the soft rot model Pectobacterium sp. SCC3193, which was isolated from a diseased potato stem in Finland in the early 1980s. Genomic approaches, including proteome and genome comparisons of all sequenced soft rot bacteria, revealed that SCC3193, previously included in the species Pectobacterium carotovorum, can now be more accurately classified as Pectobacterium wasabiae. Together with the recently revised phylogeny of a few P. carotovorum strains and an increasing number of studies on P. wasabiae, our work indicates that P. wasabiae has been unnoticed but present in potato fields worldwide. A combination of genomic approaches and in planta experiments identified features that separate SCC3193 and other P. wasabiae strains from the rest of soft rot bacteria, such as the absence of a type III secretion system that contributes to virulence of other soft rot species. Experimentally established virulence determinants include the putative transcriptional regulator SirB, two partially redundant type VI secretion systems and two horizontally acquired clusters (Vic1 and Vic2), which contain predicted virulence genes. Genome comparison also revealed other interesting traits that may be related to life in planta or other specific environmental conditions. These traits include a predicted benzoic acid/salicylic acid carboxyl methyltransferase of eukaryotic origin. The novelties found in this work indicate that soft rot bacteria have a reservoir of unknown traits that may be utilized in the poorly understood latent stage in planta. The genomic approaches and the comparison of the model strain SCC3193 to other sequenced Pectobacterium strains, including the type strain of P. wasabiae, provides a solid basis for further investigation of the virulence, distribution and phylogeny of soft rot bacteria and, potentially, other bacteria as well. PMID:23133391

Evolution of novel wood decay mechanisms in Agaricales revealed by the genome sequences of Fistulina hepatica and Cylindrobasidium torrendii

DOE PAGES

Floudas, Dimitrios; Held, Benjamin W.; Riley, Robert; ...

2015-02-12

Wood decay mechanisms in Agaricomycotina have been traditionally separated in two categories termed white and brown rot. Recently the accuracy of such a dichotomy has been questioned. In this paper, we present the genome sequences of the white-rot fungus Cylindrobasidium torrendii and the brown-rot fungus Fistulina hepatica both members of Agaricales, combining comparative genomics and wood decay experiments. C. torrendii is closely related to the white-rot root pathogen Armillaria mellea, while F. hepatica is related to Schizophyllum commune, which has been reported to cause white rot. Our results suggest that C. torrendii and S. commune are intermediate between white-rot andmore » brown-rot fungi, but at the same time they show characteristics of decay that resembles soft rot. Both species cause weak wood decay and degrade all wood components but leave the middle lamella intact. Their gene content related to lignin degradation is reduced, similar to brown-rot fungi, but both have maintained a rich array of genes related to carbohydrate degradation, similar to white-rot fungi. These characteristics appear to have evolved from white-rot ancestors with stronger ligninolytic ability. F. hepatica shows characteristics of brown rot both in terms of wood decay genes found in its genome and the decay that it causes. However, genes related to cellulose degradation are still present, which is a plesiomorphic characteristic shared with its white-rot ancestors. Four wood degradation-related genes, homologs of which are frequently lost in brown-rot fungi, show signs of pseudogenization in the genome of F. hepatica. These results suggest that transition toward a brown-rot lifestyle could be an ongoing process in F. hepatica. Finally, our results reinforce the idea that wood decay mechanisms are more diverse than initially thought and that the dichotomous separation of wood decay mechanisms in Agaricomycotina into white rot and brown rot should be revisited.« less

Evolution of novel wood decay mechanisms in Agaricales revealed by the genome sequences of Fistulina hepatica and Cylindrobasidium torrendii

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

Floudas, Dimitrios; Held, Benjamin W.; Riley, Robert

Wood decay mechanisms in Agaricomycotina have been traditionally separated in two categories termed white and brown rot. Recently the accuracy of such a dichotomy has been questioned. In this paper, we present the genome sequences of the white-rot fungus Cylindrobasidium torrendii and the brown-rot fungus Fistulina hepatica both members of Agaricales, combining comparative genomics and wood decay experiments. C. torrendii is closely related to the white-rot root pathogen Armillaria mellea, while F. hepatica is related to Schizophyllum commune, which has been reported to cause white rot. Our results suggest that C. torrendii and S. commune are intermediate between white-rot andmore » brown-rot fungi, but at the same time they show characteristics of decay that resembles soft rot. Both species cause weak wood decay and degrade all wood components but leave the middle lamella intact. Their gene content related to lignin degradation is reduced, similar to brown-rot fungi, but both have maintained a rich array of genes related to carbohydrate degradation, similar to white-rot fungi. These characteristics appear to have evolved from white-rot ancestors with stronger ligninolytic ability. F. hepatica shows characteristics of brown rot both in terms of wood decay genes found in its genome and the decay that it causes. However, genes related to cellulose degradation are still present, which is a plesiomorphic characteristic shared with its white-rot ancestors. Four wood degradation-related genes, homologs of which are frequently lost in brown-rot fungi, show signs of pseudogenization in the genome of F. hepatica. These results suggest that transition toward a brown-rot lifestyle could be an ongoing process in F. hepatica. Finally, our results reinforce the idea that wood decay mechanisms are more diverse than initially thought and that the dichotomous separation of wood decay mechanisms in Agaricomycotina into white rot and brown rot should be revisited.« less

Evolution of novel wood decay mechanisms in Agaricales revealed by the genome sequences of Fistulina hepatica and Cylindrobasidium torrendii

PubMed Central

Floudas, Dimitrios; Held, Benjamin W.; Riley, Robert; Nagy, Laszlo G.; Koehler, Gage; Ransdell, Anthony S.; Younus, Hina; Chow, Julianna; Chiniquy, Jennifer; Lipzen, Anna; Tritt, Andrew; Sun, Hui; Haridas, Sajeet; LaButti, Kurt; Ohm, Robin A.; Kües, Ursula; Blanchette, Robert A.; Grigoriev, Igor V.; Minto, Robert E.; Hibbett, David S.

2015-01-01

Wood decay mechanisms in Agaricomycotina have been traditionally separated in two categories termed white and brown rot. Recently the accuracy of such a dichotomy has been questioned. Here, we present the genome sequences of the white rot fungus Cylindrobasidium torrendii and the brown rot fungus Fistulina hepatica both members of Agaricales, combining comparative genomics and wood decay experiments. Cylindrobasidium torrendii is closely related to the white-rot root pathogen Armillaria mellea, while F. hepatica is related to Schizophyllum commune, which has been reported to cause white rot. Our results suggest that C. torrendii and S. commune are intermediate between white-rot and brown-rot fungi, but at the same time they show characteristics of decay that resembles soft rot. Both species cause weak wood decay and degrade all wood components but leave the middle lamella intact. Their gene content related to lignin degradation is reduced, similar to brown-rot fungi, but both have maintained a rich array of genes related to carbohydrate degradation, similar to white-rot fungi. These characteristics appear to have evolved from white-rot ancestors with stronger ligninolytic ability. Fistulina hepatica shows characteristics of brown rot both in terms of wood decay genes found in its genome and the decay that it causes. However, genes related to cellulose degradation are still present, which is a plesiomorphic characteristic shared with its white-rot ancestors. Four wood degradation-related genes, homologs of which are frequently lost in brown-rot fungi, show signs of pseudogenization in the genome of F. hepatica. These results suggest that transition towards a brown rot lifestyle could be an ongoing process in F. hepatica. Our results reinforce the idea that wood decay mechanisms are more diverse than initially thought and that the dichotomous separation of wood decay mechanisms in Agaricomycotina into white rot and brown rot should be revisited. PMID:25683379

Evolution of novel wood decay mechanisms in Agaricales revealed by the genome sequences of Fistulina hepatica and Cylindrobasidium torrendii.

PubMed

Floudas, Dimitrios; Held, Benjamin W; Riley, Robert; Nagy, Laszlo G; Koehler, Gage; Ransdell, Anthony S; Younus, Hina; Chow, Julianna; Chiniquy, Jennifer; Lipzen, Anna; Tritt, Andrew; Sun, Hui; Haridas, Sajeet; LaButti, Kurt; Ohm, Robin A; Kües, Ursula; Blanchette, Robert A; Grigoriev, Igor V; Minto, Robert E; Hibbett, David S

2015-03-01

Wood decay mechanisms in Agaricomycotina have been traditionally separated in two categories termed white and brown rot. Recently the accuracy of such a dichotomy has been questioned. Here, we present the genome sequences of the white-rot fungus Cylindrobasidium torrendii and the brown-rot fungus Fistulina hepatica both members of Agaricales, combining comparative genomics and wood decay experiments. C. torrendii is closely related to the white-rot root pathogen Armillaria mellea, while F. hepatica is related to Schizophyllum commune, which has been reported to cause white rot. Our results suggest that C. torrendii and S. commune are intermediate between white-rot and brown-rot fungi, but at the same time they show characteristics of decay that resembles soft rot. Both species cause weak wood decay and degrade all wood components but leave the middle lamella intact. Their gene content related to lignin degradation is reduced, similar to brown-rot fungi, but both have maintained a rich array of genes related to carbohydrate degradation, similar to white-rot fungi. These characteristics appear to have evolved from white-rot ancestors with stronger ligninolytic ability. F. hepatica shows characteristics of brown rot both in terms of wood decay genes found in its genome and the decay that it causes. However, genes related to cellulose degradation are still present, which is a plesiomorphic characteristic shared with its white-rot ancestors. Four wood degradation-related genes, homologs of which are frequently lost in brown-rot fungi, show signs of pseudogenization in the genome of F. hepatica. These results suggest that transition toward a brown-rot lifestyle could be an ongoing process in F. hepatica. Our results reinforce the idea that wood decay mechanisms are more diverse than initially thought and that the dichotomous separation of wood decay mechanisms in Agaricomycotina into white rot and brown rot should be revisited. Copyright © 2015 Elsevier Inc. All rights reserved.

Draft Genome Sequences of Dickeya sp. Isolates B16 (NIB Z 2098) and S1 (NIB Z 2099) Causing Soft Rot of Phalaenopsis Orchids.

PubMed

Alič, Špela; Naglič, Tina; Llop, Pablo; Toplak, Nataša; Koren, Simon; Ravnikar, Maja; Dreo, Tanja

2015-09-10

The genus Dickeya contains bacteria causing soft rot of economically important crops and ornamental plants. Here, we report the draft genome sequences of two Dickeya sp. isolates from rotted leaves of Phalaenopsis orchids. Copyright © 2015 Alič et al.

Pruning of Manchurian crabapple for management of speck rot and Sphaeropsis rot in apple

USDA-ARS?s Scientific Manuscript database

Phacidiopycnis washingtonensis and Sphaeropsis pyriputrescens are two important quarantined fungal pathogens that cause post-harvest speck rot and Sphaeropsis rot, respectively, in apple. Due to detection of these pathogens in fruit shipments and quarantine regulation, export of apple from Washingto...

A diagnostic guide for Fusarium Root Rot of pea

USDA-ARS?s Scientific Manuscript database

Fusarium root rot, caused by Fusarium solani f. sp. pisi, is a major root rot pathogen in pea production areas worldwide. Here we provide a diagnostic guide that describes: the taxonomy of the pathogen, signs and symptoms of the pathogen, host range, geographic distribution, methods used to isolate ...

Nitric oxide detoxification by Fusarium verticillioides flavohemoglobin and role in pathogenicity of maize

USDA-ARS?s Scientific Manuscript database

Fusarium verticillioides is a non-obligate plant pathogen of maize causing a number of specific diseases, including root rot, kernel rot, seed rot, stalk rot, and seedling blight. The saprophytic nature of this fungus, its production of the mycotoxin fumonisin, and complex relationship maize puts t...

Isolation, characterization, and evaluation of multi-trait plant growth promoting rhizobacteria for their growth promoting and disease suppressing effects on ginger.

PubMed

Dinesh, Raghavan; Anandaraj, Muthuswamy; Kumar, Aundy; Bini, Yogiyar Kundil; Subila, Kizhakke Purayil; Aravind, Ravindran

2015-04-01

In this study, 100 PGPR strains isolated from different varieties of ginger (Zingiber officinale Rosc.) were first characterized for their morphological, biochemical, and nutrient mobilization traits in vitro. The PGPR were also screened in vitro for inhibition of Pythium myriotylum causing soft rot in ginger. Results revealed that only five PGPR showed >70% suppression of P. myriotylum. These 5 PGPR viz., GRB (Ginger rhizobacteria) 25--Burkholderia cepacia, GRB35--Bacillus amyloliquefaciens; GRB58--Serratia marcescens; GRB68--S. marcescens; GRB91--Pseudomonas aeruginosa were used for further growth promotion and biocontrol studies in the green house and field. The green house study revealed that GRB35 (B. amyloliquefaciens) and GRB68 (S. marcescens) registered markedly higher sprouting (96.3%) and lower disease incidence (48.1%) and greater rhizome yield (365.6 g pot(-1) and 384.4 g pot(-1), respectively), while control registered the lowest sprouting (66%), maximum soft rot incidence (100%) and lowest rhizome yield (134.4 g pot(-1)). In the field experiments also, GRB68 (S. marcescens) and GRB35 (B. amyloliquefaciens) registered the greatest sprouting (80% each), markedly lower soft rot incidence (5.2% and 7.3%, respectively) and higher yield (5.0 and 4.3 kg(3)m(-2), respectively) compared to chemicals like Streptomycin sulphate (73.0%, 18.5% and 2.3 kg(3)m(-2), respectively), Metalaxyl-Mancozeb (73.0%, 14.0% and 3.8 kg(3)m(-2), respectively) and control (73.0%, 25.1% and 2.2 kg 3m(-2), respectively). Overall, the results suggested that for growth promotion and management of soft rot disease in ginger, GRB35 B. amyloliquefaciens and GRB68 S. marcescens could be good alternatives to chemical measures. Since, the latter has been reported to be an opportunistic human pathogen, we recommend the use of B. amyloliquefaciens for integration into nutrient and disease management schedules for ginger cultivation. Copyright © 2015 Elsevier GmbH. All rights reserved.

Occurrence of Root Rot and Vascular Wilt Diseases in Roselle (Hibiscus sabdariffa L.) in Upper Egypt.

PubMed

Hassan, Naglaa; Shimizu, Masafumi; Hyakumachi, Mitsuro

2014-03-01

Roselle (Hibiscus sabdariffa L.) family Malvaceae is an important crop used in food, cosmetics and pharmaceutics industries. Roselle is cultivated mainly in Upper Egypt (Qena and Aswan governorates) producing 94% of total production. Root rot disease of roselle is one of the most important diseases that attack both seedlings and adult plants causing serious losses in crop productivity and quality. The main objective of the present study is to identify and characterize pathogens associated with root rot and wilt symptoms of roselle in Qena, Upper Egypt and evaluate their pathogenicity under greenhouse and field condition. Fusarium oxysporum, Macrophomina phaseolina, Fusarium solani, Fusarium equiseti and Fusarium semitectum were isolated from the natural root rot diseases in roselle. All isolated fungi were morphologically characterized and varied in their pathogenic potentialities. They could attack roselle plants causing damping-off and root rot/wilt diseases in different pathogenicity tests. The highest pathogenicity was caused by F. oxysporum and M. phaseolina followed by F. solani. The least pathogenic fungi were F. equiseti followed by F. semitectum. It obviously noted that Baladi roselle cultivar was more susceptible to infection with all tested fungi than Sobhia 17 under greenhouse and field conditions. This is the first report of fungal pathogens causing root rot and vascular wilt in roselle in Upper Egypt.

Wood-Destroying Soft Rot Fungi in the Historic Expedition Huts of Antarctica

PubMed Central

Blanchette, Robert A.; Held, Benjamin W.; Jurgens, Joel A.; McNew, Douglas L.; Harrington, Thomas C.; Duncan, Shona M.; Farrell, Roberta L.

2004-01-01

Three expedition huts in the Ross Sea region of Antarctica, built between 1901 and 1911 by Robert F. Scott and Ernest Shackleton, sheltered and stored the supplies for up to 48 men for 3 years during their explorations and scientific investigation in the South Pole region. The huts, built with wood taken to Antarctica by the early explorers, have deteriorated over the past decades. Although Antarctica has one of the coldest and driest environments on earth, microbes have colonized the wood and limited decay has occurred. Some wood in contact with the ground contained distinct microscopic cavities within secondary cell walls caused by soft rot fungi. Cadophora spp. could be cultured from decayed wood and other woods sampled from the huts and artifacts and were commonly associated with the soft rot attack. By using internal transcribed spacer sequences of ribosomal DNA and morphological characteristics, several species of Cadophora were identified, including C. malorum, C. luteo-olivacea, and C. fastigiata. Several previously undescribed Cadophora spp. also were found. At the Cape Evans and Cape Royds huts, Cadophora spp. commonly were isolated from wood in contact with the ground but were not always associated with soft rot decay. Pure cultures of Cadophora used in laboratory decay studies caused dark staining of all woods tested and extensive soft rot in Betula and Populus wood. The presence of Cadophora species, but only limited decay, suggests there is no immediate threat to the structural integrity of the huts. These fungi, however, are widely found in wood from the historic huts and have the capacity to cause extensive soft rot if conditions that are more conducive to decay become common. PMID:15006750

Soft Rot of Eggplant (Solanum melongena) Caused by Choanephora cucurbitarum in Korea

PubMed Central

Jee, Hyeong-Jin

2005-01-01

In April 2002 and 2003, soft rot on fruit of eggplant (Solanum melongena) caused by Choanephora cucurbitarum was observed in the experimental fields at Gyeongnam Agricultural Research and Extension Services in Korea. The disease began with water-soaking and dark-green lesions, and then the infected tissues were rapidly rotten. Sporangium was subglobose in shape and sized 40~130 µm. Monosporous sporangiola were elliptic, fusiform or ovoid, brown in color, and measured as 12~20 × 6~14 µm. Sporangiospores having three or more appendages were elliptic, fusiform or ovoid in shape, dark brown or brown in color, and sized 14~20 × 7~16 µm. The fungus grew well on potato dextrose agar between 15 and 40℃ and its optimum growth temperature was 30℃. Based on morphological characteristics, the causal fungus of the fruit soft rot of eggplant was identified as C. cucurbitarum. This is the first report on the soft rot of S. melongena caused by C. cucurbitarum in Korea. PMID:24049494

Detection, identification and differentiation of Pectobacterium and Dickeya species causing potato blackleg and tuber soft rot: a review

PubMed Central

Czajkowski, R; Pérombelon, MCM; Jafra, S; Lojkowska, E; Potrykus, M; van der Wolf, JM; Sledz, W

2015-01-01

The soft rot Enterobacteriaceae (SRE) Pectobacterium and Dickeya species (formerly classified as pectinolytic Erwinia spp.) cause important diseases on potato and other arable and horticultural crops. They may affect the growing potato plant causing blackleg and are responsible for tuber soft rot in storage thereby reducing yield and quality. Efficient and cost-effective detection and identification methods are essential to investigate the ecology and pathogenesis of the SRE as well as in seed certification programmes. The aim of this review was to collect all existing information on methods available for SRE detection. The review reports on the sampling and preparation of plant material for testing and on over thirty methods to detect, identify and differentiate the soft rot and blackleg causing bacteria to species and subspecies level. These include methods based on biochemical characters, serology, molecular techniques which rely on DNA sequence amplification as well as several less-investigated ones. PMID:25684775

Occurrence of Root Rot and Vascular Wilt Diseases in Roselle (Hibiscus sabdariffa L.) in Upper Egypt

PubMed Central

Hassan, Naglaa; Shimizu, Masafumi

2014-01-01

Roselle (Hibiscus sabdariffa L.) family Malvaceae is an important crop used in food, cosmetics and pharmaceutics industries. Roselle is cultivated mainly in Upper Egypt (Qena and Aswan governorates) producing 94% of total production. Root rot disease of roselle is one of the most important diseases that attack both seedlings and adult plants causing serious losses in crop productivity and quality. The main objective of the present study is to identify and characterize pathogens associated with root rot and wilt symptoms of roselle in Qena, Upper Egypt and evaluate their pathogenicity under greenhouse and field condition. Fusarium oxysporum, Macrophomina phaseolina, Fusarium solani, Fusarium equiseti and Fusarium semitectum were isolated from the natural root rot diseases in roselle. All isolated fungi were morphologically characterized and varied in their pathogenic potentialities. They could attack roselle plants causing damping-off and root rot/wilt diseases in different pathogenicity tests. The highest pathogenicity was caused by F. oxysporum and M. phaseolina followed by F. solani. The least pathogenic fungi were F. equiseti followed by F. semitectum. It obviously noted that Baladi roselle cultivar was more susceptible to infection with all tested fungi than Sobhia 17 under greenhouse and field conditions. This is the first report of fungal pathogens causing root rot and vascular wilt in roselle in Upper Egypt. PMID:24808737

Pathogenicity and genetic diversity of Fusarium oxysporum causing soybean root rot in northeast China

USDA-ARS?s Scientific Manuscript database

Soybean is an important edible legume cultivated around the world. However, soybean production is seriously impacted by the widespread occurrence of root rot disease. In this study, genetic diversity and pathogenicity of Fusarium oxysporum associated with root rot of soybean in Heilongjiang province...

The Salmonella transcriptome in lettuce and cilantro soft rot reveals a niche overlap with the animal host intestine

USDA-ARS?s Scientific Manuscript database

Fresh vegetables have been recurrently associated with salmonellosis outbreaks and Salmonella contamination of retail produce has been correlated positively with the presence of soft rot disease. We observed that Salmonella enterica Typhimurium SL1344 grows to 50-fold greater populations in the pres...

Determining resistance to soft-rot fungi

Treesearch

C. G. Duncan

1965-01-01

A laboratory procedure is outlined that incorporates techniques found to promote soft rot by several fungi. This procedure employs either an agar or a soil substrate. Also presented are the principal findings of experiments underlying the procedure. Results of tests conducted according to the suggested procedure are illustrated. The overall decay resistance of the...

Isolation and identification of bacteria causing blackleg and soft rot of potato

USDA-ARS?s Scientific Manuscript database

Both Dickeya and Pectobacterium spp. are important causal agents of blackleg and soft rot of potato. To understand the outbreak of blackleg in the Northeastern U.S. in 2015, samples were collected from symptomatic plants, dormant tubers, and surface water in 2016 and 2017. Diseased plant samples wer...

Carvacrol and eugenol effectively inhibit Rhizopus stolonifer and control postharvest soft rot decay in peaches.

PubMed

Zhou, D; Wang, Z; Li, M; Xing, M; Xian, T; Tu, K

2018-01-01

This study aimed to investigate the antifungal mechanism of carvacrol and eugenol to inhibit Rhizopus stolonifer and the control of postharvest soft rot decay in peaches. To investigate the antifungal mechanism, the effects of carvacrol and eugenol on the mycelium growth, leakages of cytoplasmic contents, mycelium morphology, cell membrane and membrane composition of R. stolonifer were studied. Carvacrol and eugenol both exhibited dose-dependent antifungal activity against R. stolonifer, carvacrol at a concentration of 2 μl per plant and eugenol at a concentration of 4 μl per plant inhibited fungal growth completely. The two essential oils (EOs) increased cell membrane penetrability and caused the leakage of cytoplasm, nucleic acid and protein content. The observation using scanning electron microscopy and fluorescent microscopy showed modification of the hyphal morphology and breakage of the cell plasma membrane. Decreased ergosterol contents confirmed that the two EOs could destroy the membrane of R. stolonifer. For the in vivo test, the inhibition of soft rot disease and the induction of defence-related enzymes were investigated. Carvacrol and eugenol significantly reduced the incidence and severity of soft rot decay in inoculated peaches. The best treatments for controlling soft rot decay were obtained at 0·5 μl l -1 for carvacrol and 1 μl l -1 for eugenol. The activities of defence-related enzymes in peaches were also enhanced by fumigation with two EOs. This study showed that carvacrol and eugenol could effectively inhibit the growth of R. stolonifer in vitro and successfully control the incidence of soft rot decay in honey peaches. The above findings may be the main antifungal mechanism of carvacrol and eugenol on R. stolonifer. Furthermore, carvacrol and eugenol are helpful for their commercial application on the preservation of fresh fruit. © 2017 The Society for Applied Microbiology.

Identification of Fusarium species isolated from stored apple fruit in Croatia.

PubMed

Sever, Zdravka; Ivić, Dario; Kos, Tomislav; Miličević, Tihomir

2012-12-01

Several species of the genus Fusarium can cause apple fruit to rot while stored. Since Fusarium taxonomy is very complex and has constantly been revised and updated over the last years, the aim of this study was to identify Fusarium species from rotten apples, based on combined morphological characteristics and molecular data. We identified 32 Fusarium isolates from rotten apple fruit of cultivars Golden Delicious, Jonagold, Idared, and Pink Lady, stored in Ultra Low Oxygen (ULO) conditions. Fusarium rot was detected in 9.4 % to 33.2 % of naturally infected apples, depending on the cultivar. The symptoms were similar in all four cultivars: a soft circular brown necrosis of different extent, with or without visible sporulation. Fusarium species were identified by the morphology of cultures grown on potato-dextrose agar (PDA) and carnation leaf agar (CLA). Twenty one isolates were identified as Fusarium avenaceum and confirmed as such with polymerase chain reaction (PCR) using specific primer pair FA-ITSF and FA-ITSR. F. pseudograminearum,F. semitectum, F. crookwellense, and F. compactum were identified by morphological characteristics. F.avenaceum can produce several mycotoxins and its dominance in Fusarium rot points to the risk of mycotoxin contamination of apple fruit juices and other products for human consumption. Pathogenicity tests showed typical symptoms of Fusarium rot in most of the inoculated wounded apple fruits. In this respect Fusarium avenaceum, as the dominant cause of Fusarium rot in stored apple fruits is a typical wound parasite.

Postharvest application of organic and inorganic salts to control potato (Solanum tuberosum L.) storage soft rot: plant tissue-salt physicochemical interactions.

PubMed

Yaganza, E S; Tweddell, R J; Arul, J

2014-09-24

Soft rot caused by Pectobacterium sp. is a devastating disease affecting stored potato tubers, and there is a lack of effective means of controlling this disease. In this study, 21 organic and inorganic salts were tested for their ability to control soft rot in potato tubers. In the preventive treatment, significant control of soft rot was observed with AlCl3 (≥66%) and Na2S2O3 (≥57%) and to a lesser extent with Al lactate and Na benzoate (≥34%) and K sorbate and Na propionate (≥27%). However, only a moderate control was achieved by curative treatment with AlCl3 and Na2S2O3 (42%) and sodium benzoate (≥33%). Overall, the in vitro inhibitory activity of salts was attenuated in the presence of plant tissue (in vivo) to different degrees. The inhibitory action of the salts in the preventive treatment, whether effective or otherwise, showed an inverse linear relationship with water ionization capacity (pK') of the salt ions, whereas in the curative treatment, only the effective salts showed this inverse linear relationship. Salt-plant tissue interactions appear to play a central role in the attenuated inhibitory activity of salts in potato tuber through reduction in the availability of the inhibitory ions for salt-bacteria interactions. This study demonstrates that AlCl3, Na2S2O3, and Na benzoate have potential in controlling potato tuber soft rot and provides a general basis for understanding of specific salt-tissue interactions.

Paromomycin Derived from Streptomyces sp. AG-P 1441 Induces Resistance against Two Major Pathogens of Chili Pepper.

PubMed

Balaraju, Kotnala; Kim, Chang-Jin; Park, Dong-Jin; Nam, Ki-Woong; Zhang, Kecheng; Sang, Mee Kyung; Park, Kyungseok

2016-09-28

This is the first report that paromomycin, an antibiotic derived from Streptomyces sp. AG-P 1441 (AG-P 1441), controlled Phytophthora blight and soft rot diseases caused by Phytophthora capsici and Pectobacterium carotovorum, respectively, in chili pepper (Capsicum annum L.). Chili pepper plants treated with paromomycin by foliar spray or soil drenching 7 days prior to inoculation with P. capsici zoospores showed significant (p < 0.05) reduction in disease severity (%) when compared with untreated control plants. The disease severity of Phytophthora blight was recorded as 8% and 50% for foliar spray and soil drench, respectively, at 1.0 ppm of paromomycin, compared with untreated control, where disease severity was 83% and 100% by foliar spray and soil drench, respectively. A greater reduction of soft rot lesion areas per leaf disk was observed in treated plants using paromomycin (1.0 μg/ml) by infiltration or soil drench in comparison with untreated control plants. Paromomycin treatment did not negatively affect the growth of chili pepper. Furthermore, the treatment slightly promoted growth; this growth was supported by increased chlorophyll content in paromomycin-treated chili pepper plants. Additionally, paromomycin likely induced resistance as confirmed by the expression of pathogenesis-related (PR) genes: PR-1, β-1,3-glucanase, chitinase, PR-4, peroxidase, and PR-10, which enhanced plant defense against P. capsici in chili pepper. This finding indicates that AG-P 1441 plays a role in pathogen resistance upon the activation of defense genes, by secretion of the plant resistance elicitor, paromomycin.

Fusarium algeriense sp. nov., a novel toxigenic crown rot pathogen of durum wheat from Algeria is nested within the Fusarium burgessii species complex

USDA-ARS?s Scientific Manuscript database

A novel crown rot pathogen of wheat discovered during pathogen surveys of Algeria in 2014 and 2015 is formally described here as Fusarium algeriense. Multilocus molecular phylogenetic data resolved the eight isolates of this pathogen as a genealogically exclusive species lineage within the F. burges...

Enhanced bioprocessing of lignocellulose: Wood-rot fungal saccharification and fermentation of corn fiber to ethanol

NASA Astrophysics Data System (ADS)

Shrestha, Prachand

This research aims at developing a biorefinery platform to convert corn-ethanol coproduct, corn fiber, into fermentable sugars at a lower temperature with minimal use of chemicals. White-rot (Phanerochaete chrysosporium), brown-rot (Gloeophyllum trabeum) and soft-rot (Trichoderma reesei) fungi were used in this research to biologically break down cellulosic and hemicellulosic components of corn fiber into fermentable sugars. Laboratory-scale simultaneous saccharification and fermentation (SSF) process proceeded by in-situ cellulolytic enzyme induction enhanced overall enzymatic hydrolysis of hemi/cellulose from corn fiber into simple sugars (mono-, di-, tri-saccharides). The yeast fermentation of hydrolyzate yielded 7.1, 8.6 and 4.1 g ethanol per 100 g corn fiber when saccharified with the white-, brown-, and soft-rot fungi, respectively. The highest corn-to-ethanol yield (8.6 g ethanol/100 g corn fiber) was equivalent to 42 % of the theoretical ethanol yield from starch and cellulose in corn fiber. Cellulase, xylanase and amylase activities of these fungi were also investigated over a week long solid-substrate fermentation of corn fiber. G. trabeum had the highest activities for starch (160 mg glucose/mg protein.min) and on day three of solid-substrate fermentation. P. chrysosporium had the highest activity for xylan (119 mg xylose/mg protein.min) on day five and carboxymethyl cellulose (35 mg glucose/mg protein.min) on day three of solid-substrate fermentation. T. reesei showed the highest activity for Sigma cell 20 (54.8 mg glucose/mg protein.min) on day 5 of solid-substrate fermentation. The effect of different pretreatments on SSF of corn fiber by fungal processes was examined. Corn fiber was treated at 30 °C for 2 h with alkali [2% NaOH (w/w)], alkaline peroxide [2% NaOH (w/w) and 1% H2O 2 (w/w)], and by steaming at 100 °C for 2 h. Mild pretreatment resulted in improved ethanol yields for brown- and soft-rot SSF, while white-rot and Spezyme CP SSFs showed no improvement in ethanol yields. We showed that saccharification of lignocellulosic material with a wood-rot fungal process is quite feasible. Corn fiber from wet milling was best degraded to sugars using aerobic solid state fermentation with the soft-rot fungus T. reesei. However, it was shown that both the white-rot fungus P. chrysosporium and brown-rot fungus G. trabeum had the ability to produce additional consortia of hemi/cellulose degrading enzymes. It is likely that a consortium of enzymes from these fungi would be the best approach in saccharification of lignocellulose. In all cases, a subsequent anaerobic yeast process under submerged conditions is required to ferment the released sugars to ethanol. To our knowledge, this is the first time report on production of cellulolytic enzymes from wet-milled corn fiber using white- and brown-rot fungi for sequential fermentation of corn fiber hydrolyzate to ethanol. Keywords: lignocellulose, ethanol, biofuel, bioeconomy, biomass, renewable resources, corn fiber, pretreatment, solid-substrate fermentation, simultaneous saccharification and fermentation (SSF), white-rot fungus, brown-rot fungus, soft-rot fungus, fermentable sugars, enzyme activities, cellulytic enzymes Phanerochaete chrysosporium, Gloleophyllum trabeum, Trichoderma reesei, Saccharomyces cerevisiae.

Genome Sequence of the Pectobacterium atrosepticum Strain CFBP6276, Causing Blackleg and Soft Rot Diseases on Potato Plants and Tubers

PubMed Central

Kwasiborski, Anthony; Mondy, Samuel; Beury-Cirou, Amélie

2013-01-01

Pectobacterium atrosepticum strain CFBP6276 is a pectinolytic enterobacterium causing blackleg and soft rot of the stem and tuber of Solanum tuberosum. Its virulence is under the control of quorum sensing, with N-acylhomoserine lactones as communication signals. Here, we report the genome sequence of P. atrosepticum strain CFBP6276. PMID:23788545

Quorum Sensing Signaling Molecules Produced by Reference and Emerging Soft-Rot Bacteria (Dickeya and Pectobacterium spp.)

PubMed Central

Crépin, Alexandre; Barbey, Corinne; Beury-Cirou, Amélie; Hélias, Valérie; Taupin, Laure; Reverchon, Sylvie; Nasser, William; Faure, Denis; Dufour, Alain; Orange, Nicole; Feuilloley, Marc; Heurlier, Karin; Burini, Jean-François; Latour, Xavier

2012-01-01

Background Several small diffusible molecules are involved in bacterial quorum sensing and virulence. The production of autoinducers-1 and -2, quinolone, indole and γ-amino butyrate signaling molecules was investigated in a set of soft-rot bacteria belonging to six Dickeya or Pectobacterium species including recent or emerging potato isolates. Methodology/Principal Findings Using bacterial biosensors, immunoassay, and chromatographic analysis, we showed that soft-rot bacteria have the common ability to produce transiently during their exponential phase of growth the N-3-oxo-hexanoyl- or the N-3-oxo-octanoyl-l-homoserine lactones and a molecule of the autoinducer-2 family. Dickeya spp. produced in addition the indole-3-acetic acid in tryptophan-rich conditions. All these signaling molecules have been identified for the first time in the novel Dickeya solani species. In contrast, quinolone and γ-amino butyrate signals were not identified and the corresponding synthases are not present in the available genomes of soft-rot bacteria. To determine if the variations of signal production according to growth phase could result from expression modifications of the corresponding synthase gene, the respective mRNA levels were estimated by reverse transcriptase-PCR. While the N-acyl-homoserine lactone production is systematically correlated to the synthase expression, that of the autoinducer-2 follows the expression of an enzyme upstream in the activated methyl cycle and providing its precursor, rather than the expression of its own synthase. Conclusions/Significance Despite sharing the S-adenosylmethionine precursor, no strong link was detected between the production kinetics or metabolic pathways of autoinducers-1 and -2. In contrast, the signaling pathway of autoinducer-2 seems to be switched off by the indole-3-acetic acid pathway under tryptophan control. It therefore appears that the two genera of soft-rot bacteria have similarities but also differences in the mechanisms of communication via the diffusible molecules. Our results designate autoinducer-1 lactones as the main targets for a global biocontrol of soft-rot bacteria communications, including those of emerging isolates. PMID:22539957

Attenuation of Quorum Sensing Regulated Virulence of Pectobacterium carotovorum subsp. carotovorum through an AHL Lactonase Produced by Lysinibacillus sp. Gs50

PubMed Central

Garge, Sneha S.; Nerurkar, Anuradha S.

2016-01-01

Quorum sensing (QS) is a mechanism in which Gram negative bacterial pathogens sense their population density through acyl homoserine lactones (AHLs) and regulate the expression of virulence factors. Enzymatic degradation of AHLs by lactonases, known as quorum quenching (QQ), is thus a potential strategy for attenuating QS regulated bacterial infections. We characterised the QQ activity of soil isolate Lysinibacillus sp. Gs50 and explored its potential for controlling bacterial soft rot of crop plants. Lysinibacillus sp. Gs50 inactivated AHL, which could be restored upon acidification, suggested that inactivation was due to the lactone ring hydrolysis of AHL. Heterologous expression of cloned gene for putative hydrolase (792 bp) designated adeH from Lysinibacillus sp. Gs50 produced a ~29 kDa protein which degraded AHLs of varying chain length. Mass spectrometry analysis of AdeH enzymatic reaction product revealed that AdeH hydrolyses the lactone ring of AHL and hence is an AHL lactonase. Multiple sequence alignment of the amino acid sequence of AdeH showed that it belongs to the metallo- β- lactamase superfamily, has a conserved “HXHXDH” motif typical of AHL lactonases. KM for AdeH for C6HSL was found to be 3.089 μM and the specific activity was 0.8 picomol min-1μg-1. AdeH has not so far been reported from any Lysinibacillus sp. and has less than 40% identity with known AHL lactonases. Finally we found that Lysinibacillus sp. Gs50 can degrade AHL produced by Pectobacterium carotovorum subsp. carotovorum (Pcc), a common cause of soft rot. This QQ activity causes a decrease in production of plant cell wall degrading enzymes of Pcc and attenuates symptoms of soft rot in experimental infection of potato, carrot and cucumber. Our results demonstrate the potential of Lysinibacillus sp. Gs50 as a preventive and curative biocontrol agent. PMID:27911925

Functionality of a maize chitinase potentially involved in ear rot pathogen resistance

USDA-ARS?s Scientific Manuscript database

Chitinases are thought to play a role in plant resistance to fungal pathogens by degrading the fungal cell wall, but few have been investigated to any great extent. The gene for a maize (Zea mays) chitinase “chitinase 2” previously reported to be induced by two ear rot pathogens in infected tissues ...

Development of a DNA Microarray-Based Assay for the Detection of Sugar Beet Root Rot Pathogens.

PubMed

Liebe, Sebastian; Christ, Daniela S; Ehricht, Ralf; Varrelmann, Mark

2016-01-01

Sugar beet root rot diseases that occur during the cropping season or in storage are accompanied by high yield losses and a severe reduction of processing quality. The vast diversity of microorganism species involved in rot development requires molecular tools allowing simultaneous identification of many different targets. Therefore, a new microarray technology (ArrayTube) was applied in this study to improve diagnosis of sugar beet root rot diseases. Based on three marker genes (internal transcribed spacer, translation elongation factor 1 alpha, and 16S ribosomal DNA), 42 well-performing probes enabled the identification of prevalent field pathogens (e.g., Aphanomyces cochlioides), storage pathogens (e.g., Botrytis cinerea), and ubiquitous spoilage fungi (e.g., Penicillium expansum). All probes were proven for specificity with pure cultures from 73 microorganism species as well as for in planta detection of their target species using inoculated sugar beet tissue. Microarray-based identification of root rot pathogens in diseased field beets was successfully confirmed by classical detection methods. The high discriminatory potential was proven by Fusarium species differentiation based on a single nucleotide polymorphism. The results demonstrate that the ArrayTube constitute an innovative tool allowing a rapid and reliable detection of plant pathogens particularly when multiple microorganism species are present.

7 CFR 51.3410 - Grades.

Code of Federal Regulations, 2010 CFR

2010-01-01

... Rot; (vi) Insects, worms or larvae; (vii) Soft rot and wet breakdown; and, (viii) Loose sprouts, dirt..., (viii) Loose sprouts, dirt and foreign material. (3) Free from serious damage by any cause. (4) Size...

Impacts of fungal stalk rot pathogens on physicochemical properties of sorghum grain

USDA-ARS?s Scientific Manuscript database

Stalk rot diseases are among the most ubiquitous and damaging fungal diseases of sorghum worldwide. Although reports of quantitative stalk rot yield losses are available, the impact of stalk rot on the physicochemical attributes of sorghum grain is currently unknown. This study was conducted to test...

Evaluating host resistance to Macrophomina crown rot in strawberry

USDA-ARS?s Scientific Manuscript database

Macrophomina crown rot, caused by the soilborne fungus Macrophomina phaseolina, is an emerging pathogen in California strawberry production. When established, the pathogen can cause extensive plant decline and mortality. Host resistance will be a critical tool for managing this disease and guiding ...

Occurrence of the root-rot pathogen, Fusarium commune, in midwestern and western United States

Treesearch

J. E. Stewart; R. K. Dumroese; N. B. Klopfenstein; M. -S. Kim

2012-01-01

Fusarium commune can cause damping-off and root rot of conifer seedlings in forest nurseries. The pathogen is only reported in Oregon, Idaho, and Washington within United States. Fusarium isolates were collected from midwestern and western United States to determine occurrence of this pathogen. DNA sequences of mitochondrial small subunit gene were used to identify F....

Trichoderma viride induces pathogenesis related defense response against rot pathogen infection in groundnut (Arachis hypogaea L.).

PubMed

Gajera, H P; Savaliya, Disha D; Patel, S V; Golakiya, B A

2015-08-01

The study examine induction of defense enzymes involved in phenylpropanoid pathway and accumulation of pathogenesis related proteins in rot pathogen (Aspergillus niger Van Tieghem) challenged groundnut seedlings in response to Trichoderma viride JAU60. Seeds of five groundnut varieties differing in collar rot susceptibility were sown under non-infested, pathogen infested and pathogen+T. viride JAU60 seed treatment. Collar rot disease evident between 31.0% (J-11, GG-2) and 67.4% (GG-20) in different groundnut varieties under pathogen infested which was significantly reduced from 58.1% (J-11, GG-2) to 51.6% (GG-20) by Trichoderma treatment. The specific activities of polyphenol oxidase (EC 1.14.18.1) and β-1,3 glucanase (EC 3.2.1.6) elevated 3.5 and 2.3-fold, respectively, at 3 days; phenylalanine ammonia lyase (EC 4.3.1.5) evident 1.6-fold higher at 6 days; and chitinase (EC 3.2.1.14) sustained 2.3-2.8 folds up to 9 days in Trichoderma treated+pathogen infested seedlings of tolerant varieties (J-11, GG-2) compared with moderate and susceptible (GAUG-10, GG-13, GG-20). T. viride JAU60 induces defense enzymes in a different way for tolerant and susceptible varieties to combat the disease. This study indicates the synergism activation of defense enzymes under the pathogenic conditions or induced resistance by T. viride JAU60 in a different groundnut varieties susceptible to collar rot disease. Copyright © 2015 Elsevier B.V. All rights reserved.

Extensive sampling of basidiomycete genomes demonstrates inadequacy of the white-rot/brown-rot paradigm for wood decay fungi

Treesearch

Robert Riley; Asaf A. Salamov; Daren W. Brown; Laszlo G. Nagy; Dimitrios Floudas; Benjamin W. Held; Anthony Levasseur; Vincent Lombard; Emmanuelle Morin; Robert Otillar; Erika A. Lindquist; Hui Sun; Kurt M. LaButti; Jeremy Schmutz; Dina Jabbour; Hong Luo; Scott E. Baker; Antonio G. Pisabarro; Jonathan D. Walton; Robert A. Blanchette; Bernard Henrissat; Francis Martin; Daniel Cullen; David S. Hibbett; Igor V. Grigoriev

2014-01-01

Basidiomycota (basidiomycetes) make up 32% of the described fungi and include most wood-decaying species, as well as pathogens and mutualistic symbionts. Wood-decaying basidiomycetes have typically been classified as either white rot or brown rot, based on the ability (in white rot only) to degrade lignin along with cellulose and hemicellulose. Prior genomic...

Stem rots of oil palm caused by Ganoderma boninense: pathogen biology and epidemiology.

PubMed

Pilotti, C A

2005-01-01

Oil palm (Elaeis guineensis Jacq.) has been grown in Papua New Guinea since the early 1960s. The most important disease of oil palm in PNG is a stem rot of the palm base. This is the same disease that constitutes a major threat to sustainable oil palm production in SE Asia. Investigations into the causal pathogen have revealed that the stem rots in PNG are caused predominantly by the basidiomycete Ganoderma boninense, with a minor pathogen identified as G. tornatum G. tornatum was found to have a broad host range whereas G. boninense appears to be restricted to palms. The population structure of G. boninense was investigated using inter-fertility studies between isolates collected from basal stem rots on oil palm. Although the G. boninense field populations are predominantly comprised of distinct individuals, a number of isolates were found that share single mating alleles. This indicates that out-crossing had occurred over several generations in the resident or wild population of G. boninense prior to colonization of oil palm. No direct hereditary relationship between isolates on neighbouring diseased palms was found, although an indirect link between isolates causing upper stem rot and basal stem rot was detected.

Persistence of Gliocephalotrichum spp. causing fruit rot of rambutan (Nephelium lappaceum L.) in Puerto Rico

USDA-ARS?s Scientific Manuscript database

Worldwide, fruit rot of rambutan is an important problem that limits the storage, marketing and long-distance transportation of the fruit. A complex of pathogens has been reported to cause fruit rot of rambutan and significant post-harvest economic losses. During 2009 and 2011 rambutan fruit rot was...

The Mitochondrial Genome of Moniliophthora roreri, the frosty pod rot pathogen of cacao

USDA-ARS?s Scientific Manuscript database

Moniliophthora roreri and Moniliophthora perniciosa are closely related basidiomycetes that cause two important diseases in cacao (Theobroma cacao L.): frosty pod rot and the witches' broom disease, respectively. A comparison of the complete mitochondrial genomes of these pathogens shows a high degr...

Occurrence of the root-rot pathogen, Fusarium commune, in forest nurseries of the midwestern and western United States

Treesearch

Mee-Sook Kim; Jane E. Stewart; R. Kasten Dumroese; Ned B. Klopfenstein

2012-01-01

Fusarium commune can cause damping-off and root rot of conifer seedlings in forest nurseries, and this pathogen has been previously reported from Oregon, Idaho, and Washington, USA. We collected Fusarium isolates from additional nurseries in the midwestern and western USA to more fully determine occurrence of this pathogen. We used DNA sequences of the mitochondrial...

Management of bull’s eye rot using preharvest and postharvest fungicides

USDA-ARS?s Scientific Manuscript database

Neofabraea perennans and N. kienholzii are major causal pathogens of bull’s eye rot in apple in Eastern WA. These fungi cause significant economic loss to the Washington State apple industry and have been listed as quarantine pathogens. Previous experiments indicate that fungicide treatments contain...

Moniliophthora roreri Genome and Transcriptome

USDA-ARS?s Scientific Manuscript database

Frosty pod rot disease of cacao is one of the most destructive diseases of cacao and at this time is limited to regions in South America and Central America. Frosty pod rot is caused by a fungal pathogen Moniliophthora roreri, a basidiomycete that is closely related to another cacao pathogen that ca...

Huanglongbing increases Diplodia Stem End Rot in Citrus sinensis

USDA-ARS?s Scientific Manuscript database

Huanglongbing (HLB), one of the most devastating diseases of citrus is caused by the a-Proteobacteria Candidatus Liberibacter. Diplodia natalensis Pole-Evans is a fungal pathogen which has been known to cause a postharvest stem-end rot of citrus, the pathogen infects citrus fruit under the calyx, an...

Draft Genome Sequence for ICMP 5702, the Type Strain of Pectobacterium carotovorum subsp. carotovorum That Causes Soft Rot Disease on Potato

PubMed Central

Lu, Ashley; Armstrong, Karen F.

2015-01-01

Pectobacterium species are economically important bacteria that cause soft rotting of potato tubers in the field and in storage. Here, we report the draft genome sequence of the type strain for P. carotovorum subsp. carotovorum, ICMP 5702 (ATCC 15713). The genome sequence of ICMP 5702 will provide an important reference for future phylogenomic and taxonomic studies of the phytopathogenic Enterobacteriaceae. PMID:26251498

Isolation, characterization, and identification of biological control agent for potato soft rot in Bangladesh.

PubMed

Rahman, M M; Ali, M E; Khan, A A; Akanda, A M; Uddin, Md Kamal; Hashim, U; Abd Hamid, S B

2012-01-01

A total of 91 isolates of probable antagonistic bacteria of potato soft rot bacterium Erwinia carotovora subsp. carotovora (Ecc) were extracted from rhizospheres and endophytes of various crop plants, different soil varieties, and atmospheres in the potato farming areas of Bangladesh. Antibacterial activity of the isolated probable antagonistic bacteria was tested in vitro against the previously identified most common and most virulent soft rot causing bacterial strain Ecc P-138. Only two isolates E-45 and E-65 significantly inhibited the in vitro growth of Ecc P-138. Physiological, biochemical, and carbon source utilization tests identified isolate E-65 as a member of the genus Bacillus and the isolate E-45 as Lactobacillus sp. The stronger antagonistic activity against Ecc P-138 was found in E-65 in vitro screening and storage potatoes. E-65 reduced the soft rot infection to 22-week storage potatoes of different varieties by 32.5-62.5% in model experiment, demonstrating its strong potential to be used as an effective biological control agent for the major pectolytic bacteria Ecc. The highest (62.5%) antagonistic effect of E-65 was observed in the Granola and the lowest (32.7%) of that was found in the Cardinal varieties of the Bangladeshi potatoes. The findings suggest that isolate E-65 could be exploited as a biocontrol agent for potato tubers.

Isolation, Characterization, and Identification of Biological Control Agent for Potato Soft Rot in Bangladesh

PubMed Central

Rahman, M. M.; Ali, M. E.; Khan, A. A.; Akanda, A. M.; Uddin, Md. Kamal; Hashim, U.; Abd Hamid, S. B.

2012-01-01

A total of 91 isolates of probable antagonistic bacteria of potato soft rot bacterium Erwinia carotovora subsp. carotovora (Ecc) were extracted from rhizospheres and endophytes of various crop plants, different soil varieties, and atmospheres in the potato farming areas of Bangladesh. Antibacterial activity of the isolated probable antagonistic bacteria was tested in vitro against the previously identified most common and most virulent soft rot causing bacterial strain Ecc P-138. Only two isolates E-45 and E-65 significantly inhibited the in vitro growth of Ecc P-138. Physiological, biochemical, and carbon source utilization tests identified isolate E-65 as a member of the genus Bacillus and the isolate E-45 as Lactobacillus sp. The stronger antagonistic activity against Ecc P-138 was found in E-65 in vitro screening and storage potatoes. E-65 reduced the soft rot infection to 22-week storage potatoes of different varieties by 32.5–62.5% in model experiment, demonstrating its strong potential to be used as an effective biological control agent for the major pectolytic bacteria Ecc. The highest (62.5%) antagonistic effect of E-65 was observed in the Granola and the lowest (32.7%) of that was found in the Cardinal varieties of the Bangladeshi potatoes. The findings suggest that isolate E-65 could be exploited as a biocontrol agent for potato tubers. PMID:22645446

Population genomic analyses of the brown root-rot pathogen, Phellinus noxius, examine potential invasive spread among Pacific islands

Treesearch

Jane E. Stewart; Mee-Sook Kim; Louise Shuey; Norio Sahashi; Yuko Ota; Robert L. Schlub; Phil G. Cannon; Ned B. Klopfenstein

2016-01-01

Phellinus noxius (Corner) G. H. Cunn is a vastly destructive, fast-growing fungal pathogen that affects a wide range of woody hosts in pan-tropical areas, including Asia, Australia, Africa, and Oceania (Ann et al. 2002; Figure 1) . This pathogen causes brown root-rot disease on cacao, coffee, and rubber, as well as diverse fruit, nut, ornamental, and other...

Rice Sheath Rot: An Emerging Ubiquitous Destructive Disease Complex

PubMed Central

Bigirimana, Vincent de P.; Hua, Gia K. H.; Nyamangyoku, Obedi I.; Höfte, Monica

2015-01-01

Around one century ago, a rice disease characterized mainly by rotting of sheaths was reported in Taiwan. The causal agent was identified as Acrocylindrium oryzae, later known as Sarocladium oryzae. Since then it has become clear that various other organisms can cause similar disease symptoms, including Fusarium sp. and fluorescent pseudomonads. These organisms have in common that they produce a range of phytotoxins that induce necrosis in plants. The same agents also cause grain discoloration, chaffiness, and sterility and are all seed-transmitted. Rice sheath rot disease symptoms are found in all rice-growing areas of the world. The disease is now getting momentum and is considered as an important emerging rice production threat. The disease can lead to variable yield losses, which can be as high as 85%. This review aims at improving our understanding of the disease etiology of rice sheath rot and mainly deals with the three most reported rice sheath rot pathogens: S. oryzae, the Fusarium fujikuroi complex, and Pseudomonas fuscovaginae. Causal agents, pathogenicity determinants, interactions among the various pathogens, epidemiology, geographical distribution, and control options will be discussed. PMID:26697031

Root rots of common and tepary beans in Puerto Rico

USDA-ARS?s Scientific Manuscript database

Root rots are a disease complex affecting common bean and can be severe in bean growing areas in the tropics and subtropics. The presence of several pathogens makes it difficult to breed for resistance because of the synergistic effect of the pathogens in the host and the interaction of soil factors...

Inhibitory effect of selenium against Penicillium expansum and its possible mechanisms of action

USDA-ARS?s Scientific Manuscript database

Penicillium expansum is a widely spread fungal pathogen that causes blue mold rot in a variety of fruits. This pathogen not only induces blue mold rot but also produces patulin in affected apple fruit, a secondary metabolite that is toxic to humans and animals. Currently, diseases caused by P. expan...

Bioactive metabolites from Stenocarpella maydis, a stalk and ear rot pathogen of maize

USDA-ARS?s Scientific Manuscript database

Stenocarpella maydis is a fungal pathogen of major importance that causes a dry-rot of maize ears and is associated with a neuromycotoxicosis in cattle grazing harvested maize fields in southern Africa and Argentina. In an effort to investigate the potential roles of S. maydis metabolites in the fun...

Molecular identification of Neofabraea species associated with bull's-eye rot on apple using rolling-circle amplification of partial EF-1α sequence.

PubMed

Lin, Huijiao; Jiang, Xiang; Yi, Jianping; Wang, Xinguo; Zuo, Ranling; Jiang, Zide; Wang, Weifang; Zhou, Erxun

2018-01-01

A rolling-circle amplification (RCA) method with padlock probes targeted on EF-1α regions was developed for rapid detection of apple bull's-eye rot pathogens, including Neofabraea malicorticis, N. perennans, N. kienholzii, and N. vagabunda (synonym: N. alba). Four padlock probes (PLP-Nm, PLP-Np, PLP-Nk, and PLP-Nv) were designed and tested against 28 samples, including 22 BER pathogen cultures, 4 closely related species, and 2 unrelated species that may cause serious apple decays. The assay successfully identified all the bull's-eye rot pathogenic fungi at the level of species, while no cross-reaction was observed in all target species and no false-positive reaction was observed with all strains used for reference. This study showed that the use of padlock probes and the combination of probe signal amplification by RCA provided an effective and sensitive method for the rapid identification of Neofabraea spp. The method could therefore be a useful tool for monitoring bull's-eye rot pathogens in port quarantine and orchard epidemiological studies.

Tolerance to Phytophthora Fruit Rot in Watermelon Plant Introductions

USDA-ARS?s Scientific Manuscript database

Phytophthora capsici is distributed worldwide, and is an aggressive pathogen with a broad host range infecting solanaceous, leguminaceous, and cucurbitaceous crops. Fruit rot, caused by P. capsici is an emerging disease in most watermelon producing regions of Southeast US. Resistance to fruit rot o...

Jasmonic acid and salicylic acid inhibit growth of three sugarbeet storage rot pathogens

USDA-ARS?s Scientific Manuscript database

Storage rots contribute to postharvest losses by consuming sucrose and increasing carbohydrate impurities that increase sugar loss to molasses during processing. They also increase root respiration rate, which causes additional sucrose loss and contributes to pile warming. Currently, storage rots ...

Phylogenetic and population analyses of the invasive brown root-rot pathogen (Phellinus noxius) highlight the existence of at least two distinct populations

Treesearch

J. E. Stewart; N. Sahashi; T. Hattori; M. Akiba; Y. Ota; L. Shuey; R. L. Schlub; N. Atibalentia; F. Brooks; A. M. C. Tang; R. Y. C. Lam; M. W. K. Leung; L. M. Chu; H. S. Kwan; A. Mohd Farid; S. S. Lee; C. -L. Chung; H. -H. Lee; Y.- C. Huang; R. -F. Liou; J. -N. Tsai; P. G. Cannon; J. W. Hanna; N. B. Klopfenstein; M. -S. Kim

2017-01-01

Phellinus noxius (Corner) G. H. Cunn is a vastly destructive, fast-growing pathogen that affects a wide range of woody hosts in pan-tropical areas, including Asia, Australia, Africa, and Oceania (Ann et al. 2002). This invasive pathogen causes brown root-rot disease on cacao, coffee, and rubber, as well as diverse fruit, nut, ornamental, and other native/exotic trees,...

Effect of Preservative Pretreatment on the Biological Durability of Corn Straw Fiber/HDPE Composites.

PubMed

Xuan, Lihui; Hui, Dongxue; Cheng, Wanli; Wong, Andrew H H; Han, Guangping; Tan, Wei Khong; Tawi, Carlson A D

2017-07-12

The effects of alkaline copper quaternary (ACQ) and zinc borate (ZB) on the resistance of corn stalk fiber (CSF)-reinforced high-density polyethylene (HDPE) composites to biodegradation were examined. Both biocides could inhibit termites, mold fungi, and wood-decay fungi, even at high CSF formulations (i.e., 60%). Additionally, ACQ enhanced the resistance of the composite materials to certain biotic stresses better than ZB. The CSF/HDPE composites treated with ACQ at the 3.0% level exhibited a superior performance against termites, white rot fungi, and brown rot fungi. ACQ treatment at the 1% level was optimal for inhibiting soft rot fungi. Furthermore, mold growth was not observed on ACQ-treated CSF/HDPE samples. The untreated CSF/HDPE composites were more susceptible to mold infections and decay than the untreated poplar/HDPE composites, likely because of an incomplete removal of the pith. The chemical features of the corn stalk may also have influenced these differences, but this possibility will need to be explored in future investigations. Furthermore, the CSF component of CSF/HDPE composites is highly susceptible to fungal attacks, with the soft rot fungus inducing the largest mass losses, followed by the white rot fungus, and then the brown rot fungus.

Effect of Preservative Pretreatment on the Biological Durability of Corn Straw Fiber/HDPE Composites

PubMed Central

Xuan, Lihui; Hui, Dongxue; Cheng, Wanli; Wong, Andrew H. H.; Han, Guangping; Tan, Wei Khong; Tawi, Carlson A. D.

2017-01-01

The effects of alkaline copper quaternary (ACQ) and zinc borate (ZB) on the resistance of corn stalk fiber (CSF)-reinforced high-density polyethylene (HDPE) composites to biodegradation were examined. Both biocides could inhibit termites, mold fungi, and wood-decay fungi, even at high CSF formulations (i.e., 60%). Additionally, ACQ enhanced the resistance of the composite materials to certain biotic stresses better than ZB. The CSF/HDPE composites treated with ACQ at the 3.0% level exhibited a superior performance against termites, white rot fungi, and brown rot fungi. ACQ treatment at the 1% level was optimal for inhibiting soft rot fungi. Furthermore, mold growth was not observed on ACQ-treated CSF/HDPE samples. The untreated CSF/HDPE composites were more susceptible to mold infections and decay than the untreated poplar/HDPE composites, likely because of an incomplete removal of the pith. The chemical features of the corn stalk may also have influenced these differences, but this possibility will need to be explored in future investigations. Furthermore, the CSF component of CSF/HDPE composites is highly susceptible to fungal attacks, with the soft rot fungus inducing the largest mass losses, followed by the white rot fungus, and then the brown rot fungus. PMID:28773150

Interpreting diplodiosis: bioactive metabolites in Stenocarpella maydis ear rot of maize

USDA-ARS?s Scientific Manuscript database

Stenocarpella maydis is a fungal pathogen of major importance that causes a dry-rot of maize ears and is associated with a neuromycotoxicosis in cattle grazing harvested maize fields in southern Africa and Argentina. Chemical investigations of S. maydis rotted kernels at harvest in Illinois led to t...

Effect of Environment and Sugar Beet Genotype on Root Rot Development and Pathogen Profile During Storage.

PubMed

Liebe, Sebastian; Varrelmann, Mark

2016-01-01

Storage rots represent an economically important factor impairing the storability of sugar beet by increasing sucrose losses and invert sugar content. Understanding the development of disease management strategies, knowledge about major storage pathogens, and factors influencing their occurrence is crucial. In comprehensive storage trials conducted under controlled conditions, the effects of environment and genotype on rot development and associated quality changes were investigated. Prevalent species involved in rot development were identified by a newly developed microarray. The strongest effect on rot development was assigned to environment factors followed by genotypic effects. Despite large variation in rot severity (sample range 0 to 84%), the spectrum of microorganisms colonizing sugar beet remained fairly constant across all treatments with dominant species belonging to the fungal genera Botrytis, Fusarium, and Penicillium. The intensity of microbial tissue necrotization was strongly correlated with sucrose losses (R² = 0.79 to 0.91) and invert sugar accumulation (R² = 0.91 to 0.95). A storage rot resistance bioassay was developed that could successfully reproduce the genotype ranking observed in storage trials. Quantification of fungal biomass indicates that genetic resistance is based on a quantitative mechanism. Further work is required to understand the large environmental influence on rot development in sugar beet.

[Research progress in root rot diseases of Chinese herbal medicine and control strategy by antagonistic microorganisms].

PubMed

Gao, Fen; Ren, Xiao-xia; Wang, Meng-liang; Qin, Xue-mei

2015-11-01

In recent years, root rot diseases of Chinese herbal medicine have been posing grave threat to the development of the traditional Chinese medicine industry. This article presents a review on the occurring situation of the root rot disease, including the occurrence of the disease, the diversity of the pathogens, the regional difference in dominant pathogens,and the complexity of symptoms and a survey of the progress in bio-control of the disease using antagonistic microorganisms. The paper also discusses the existing problems and future prospects in the research.

When Genome-Based Approach Meets the “Old but Good”: Revealing Genes Involved in the Antibacterial Activity of Pseudomonas sp. P482 against Soft Rot Pathogens

PubMed Central

Krzyżanowska, Dorota M.; Ossowicki, Adam; Rajewska, Magdalena; Maciąg, Tomasz; Jabłońska, Magdalena; Obuchowski, Michał; Heeb, Stephan; Jafra, Sylwia

2016-01-01

Dickeya solani and Pectobacterium carotovorum subsp. brasiliense are recently established species of bacterial plant pathogens causing black leg and soft rot of many vegetables and ornamental plants. Pseudomonas sp. strain P482 inhibits the growth of these pathogens, a desired trait considering the limited measures to combat these diseases. In this study, we determined the genetic background of the antibacterial activity of P482, and established the phylogenetic position of this strain. Pseudomonas sp. P482 was classified as Pseudomonas donghuensis. Genome mining revealed that the P482 genome does not contain genes determining the synthesis of known antimicrobials. However, the ClusterFinder algorithm, designed to detect atypical or novel classes of secondary metabolite gene clusters, predicted 18 such clusters in the genome. Screening of a Tn5 mutant library yielded an antimicrobial negative transposon mutant. The transposon insertion was located in a gene encoding an HpcH/HpaI aldolase/citrate lyase family protein. This gene is located in a hypothetical cluster predicted by the ClusterFinder, together with the downstream homologs of four nfs genes, that confer production of a non-fluorescent siderophore by P. donghuensis HYST. Site-directed inactivation of the HpcH/HpaI aldolase gene, the adjacent short chain dehydrogenase gene, as well as a homolog of an essential nfs cluster gene, all abolished the antimicrobial activity of the P482, suggesting their involvement in a common biosynthesis pathway. However, none of the mutants showed a decreased siderophore yield, neither was the antimicrobial activity of the wild type P482 compromised by high iron bioavailability. A genomic region comprising the nfs cluster and three upstream genes is involved in the antibacterial activity of P. donghuensis P482 against D. solani and P. carotovorum subsp. brasiliense. The genes studied are unique to the two known P. donghuensis strains. This study illustrates that mining of microbial genomes is a powerful approach for predictingthe presence of novel secondary-metabolite encoding genes especially when coupled with transposon mutagenesis. PMID:27303376

The persistence of Gliocephalotrichum bulbilium and G. simplex causing fruit rot of rambutan in Puerto Rico

USDA-ARS?s Scientific Manuscript database

Fruit rot of rambutan (Nephelium lappaceum L.) is a pre and post-harvest disease problem that affects fruit quality. Significant post-harvest losses have occurred worldwide and several pathogens have been identified in Malaysia, Costa Rica, Hawaii, Thailand, and Puerto Rico. In 2011, fruit rot was o...

First report of lily root rot caused by Thantephorus cucumeris AG 2-1 in the United States

USDA-ARS?s Scientific Manuscript database

A disease survey was undertaken in April, 2016 to profile the soilborne fungal pathogens causing root rot and lesions on lily (Lilium longiflorum) cv. Nellie White in Brookings, Oregon, Curry County. Diseased root samples were either blackened or rotted. Several fungal isolates were cultured from in...

Recent change in the nomenclature of Phellinus pini: What is Porodaedalea?

Treesearch

Jessie A. Glaeser; Karen K. Nakasone

2010-01-01

The white-rot genus Phellinus contains many important forest pathogens and saprotrophs, including those that produce heartrot, saprot, and root-rot or butt-rot. One of the most notorious species is Phellinus pini, the causal agent of "red ring decay" or "white fleck," which primarily affects older stands of...

Postharvest salicylic acid treatment reduces storage rots in water-stressed but no unstressed sugarbeet roots

USDA-ARS?s Scientific Manuscript database

Exogenous application of salicylic acid (SA) reduces storage rots in a number of postharvest crops. SA’s ability to protect sugarbeet (Beta vulgaris L.) taproots from common storage rot pathogens, however, is unknown. To determine the potential of SA to reduce storage losses caused by three common...

Fungal Disfigurement of Paper, and Soft Rot of Cedar Shingles 1

PubMed Central

Eveleigh, D. E.

1970-01-01

Disfiguration of paper by Cladosporium cladosporioides is described, and the association between “soft rot” fungi and the greying of cedar shingles in marine locations is reported. Images PMID:5463581

Assessment of Injuries Caused by Anastrepha fraterculus (Wied.) (Diptera: Tephritidae) on the Incidence of Bunch Rot Diseases in Table Grape.

PubMed

Machota, R; Bortoli, L C; Cavalcanti, F R; Botton, M; Grützmacher, A D

2016-08-01

Anastrepha fraterculus (Wied.) is the main insect pest of table grapes (Vitis vinifera) in the Southern Region of Brazil. In this study, we aimed to investigate the effect of fruit puncturing by adult females and larval infestation by A. fraterculus on the occurrence of bunch rot disease in the grape (cultivar "Itália") by evaluating grapes (a) punctured for oviposition by females of A. fraterculus, sterilized in laboratory with novaluron (40 mg L(-1)) and further spray-inoculated separately with Botrytis cinerea (1 × 10(6) conidia mL(-1)), Glomerella cingulata (1 × 10(6) conidia mL(-1)), and bacteria and yeast that cause sour rot (1 × 10(5) cells mL(-1)), (b) grapes punctured for oviposition by non-sterilized females with pathogen spraying, (c) grapes with mechanical wounds and pathogen spraying, (d) grapes with no wounds and with pathogen spraying, (e) grapes punctured for oviposition by A. fraterculus chemically sterilized in laboratory with novaluron, (f) grapes punctured for oviposition by A. fraterculus non-sterilized in laboratory with novaluron, (g) grapes with mechanical wounds, and (h) grapes with no sterilization or pathogen spraying. Our data indicated that the mechanical and oviposition wounds caused by A. fraterculus increased the percentage of grapes infected by B. cinerea, G. cingulata, and microorganisms of acid rot. The grape puncturing by A. fraterculus and the mechanical wound allows the penetration of B. cinerea and microorganisms leading to acid rot. We conclude that the fruit fly A. fraterculus may facilitate phytopathogens penetration leading to bunch rots in the table grape Itália.

Identification of a maize (Zea mays) chitinase allele sequence suitable for a role in ear rot fungal resistance

USDA-ARS?s Scientific Manuscript database

Chitinases are thought to play a role in plant resistance to pathogens, but the extent of this role is unknown. The gene for a maize chitinase “chitinase 2” previously reported to be induced by two ear rot pathogens in one maize inbred, was cloned from mRNA isolated from milk stage kernels of severa...

A novel, multiplexed, probe-based quantitative PCR assay for the soybean root- and stem-rot pathogen, Phytophthora sojae, utilizes its transposable element

USDA-ARS?s Scientific Manuscript database

Phytophthora root rot of soybean (Glycine max Merr.) is caused by the oomycete Phytophthora sojae (Kaufm. and Gerd.). P. sojae has a narrow host range, consisting primarily of soybean, and it is a serious pathogen worldwide. It exists in root and stem tissues as mycelium, wherein it can form oospo...

Involvement of phenazines and lipopeptides in interactions between Pseudomonas species and Sclerotium rolfsii, causal agent of stem rot disease on groundnut.

PubMed

Le, C N; Kruijt, M; Raaijmakers, J M

2012-02-01

To determine the role of phenazines (PHZ) and lipopeptide surfactants (LPs) produced by Pseudomonas in suppression of stem rot disease of groundnut, caused by the fungal pathogen Sclerotium rolfsii. In vitro assays showed that PHZ-producing Pseudomonas chlororaphis strain Phz24 significantly inhibited hyphal growth of S. rolfsii and suppressed stem rot disease of groundnut under field conditions. Biosynthesis and regulatory mutants of Phz24 deficient in PHZ production were less effective in pathogen suppression. Pseudomonas strains SS101, SBW25 and 267, producing viscosin or putisolvin-like LPs, only marginally inhibited hyphal growth of S. rolfsii and did not suppress stem rot disease. In contrast, Pseudomonas strain SH-C52, producing the chlorinated LP thanamycin, inhibited hyphal growth of S. rolfsii and significantly reduced stem rot disease of groundnut in nethouse and field experiments, whereas its thanamycin-deficient mutant was less effective. Phenazines and specific lipopeptides play an important role in suppression of stem rot disease of groundnut by root-colonizing Pseudomonas strains. Pseudomonas strains Phz24 and SH-C52 showed significant control of stem rot disease. Treatment of seeds or soil with these strains provides a promising supplementary strategy to control stem rot disease of groundnut. © 2011 The Authors. Journal of Applied Microbiology © 2011 The Society for Applied Microbiology.

Fungicidal activity of essential oils of Cinnamomum zeylanicum (L.) and Syzygium aromaticum (L.) Merr et L.M. Perry against crown rot and anthracnose pathogens isolated from banana.

PubMed

Ranasinghe, L; Jayawardena, B; Abeywickrama, K

2002-01-01

To develop a post-harvest treatment system against post-harvest fungal pathogens of banana using natural products. Colletotrichum musae was isolated and identified as the causative agent responsible for anthracnose peel blemishes while three fungi, namely Lasiodiplodia theobromae, C. musae and Fusarium proliferatum, were identified as causative agents responsible for crown rot. During the liquid bioassay, cinnamon [Cinnamomum zeylanicum (L.)] leaf, bark and clove [Syzygium aromaticum (L.)] oils were tested against the anthracnose and crown rot pathogens. The test oils were fungistatic and fungicidal against the test pathogens within a range of 0.03-0.11% (v/v). Cinnamon and clove essential oils could be used as antifungal agents to manage post harvest fungal diseases of banana. Cinnamon and clove essential oil could be used as alternative post-harvest treatments on banana. Banana treated with essential oil is chemically safe and acceptable to consumers. Benomyl (Benlate), which is currently used to manage fungal pathogens, can cause adverse health effects and could be replaced with volatile essential oils.

Insights into molecular and metabolic events associated with fruit response to post-harvest fungal pathogens

PubMed Central

Alkan, Noam; Fortes, Ana M.

2015-01-01

Due to post-harvest losses more than 30% of harvested fruits will not reach the consumers’ plate. Fungal pathogens play a key role in those losses, as they cause most of the fruit rots and the customer complaints. Many of the fungal pathogens are already present in the unripe fruit but remain quiescent during fruit growth until a particular phase of fruit ripening and senescence. The pathogens sense the developmental change and switch into the devastating necrotrophic life style that causes fruit rotting. Colonization of unripe fruit by the fungus initiates defensive responses that limit fungal growth and development. However, during fruit ripening several physiological processes occur that correlate with increased fruit susceptibility. In contrast to plant defenses in unripe fruit, the defense posture of ripe fruit entails a different subset of defense responses that will end with fruit rotting and losses. This review will focus on several aspects of molecular and metabolic events associated with fleshy fruit responses induced by post-harvest fungal pathogens during fruit ripening. PMID:26539204

7 CFR 51.1913 - Serious damage.

Code of Federal Regulations, 2013 CFR

2013-01-01

...) Soft ripe tomatoes or tomatoes affected by the soft rot. (b) Fresh holes or cuts, or any holes or cuts... adjacent to the stem scar and more than 1/4 inch in diameter. (h) Fruit actually infested with worms. ...

7 CFR 51.1913 - Serious damage.

Code of Federal Regulations, 2014 CFR

2014-01-01

...) Soft ripe tomatoes or tomatoes affected by the soft rot. (b) Fresh holes or cuts, or any holes or cuts... adjacent to the stem scar and more than 1/4 inch in diameter. (h) Fruit actually infested with worms. ...

Potential worldwide distribution of Fusarium dry root rot in common beans based on the optimal environment for disease occurrence.

PubMed

Macedo, Renan; Sales, Lilian Patrícia; Yoshida, Fernanda; Silva-Abud, Lidianne Lemes; Lobo, Murillo

2017-01-01

Root rots are a constraint for staple food crops and a long-lasting food security problem worldwide. In common beans, yield losses originating from root damage are frequently attributed to dry root rot, a disease caused by the Fusarium solani species complex. The aim of this study was to model the current potential distribution of common bean dry root rot on a global scale and to project changes based on future expectations of climate change. Our approach used a spatial proxy of the field disease occurrence, instead of solely the pathogen distribution. We modeled the pathogen environmental requirements in locations where in-situ inoculum density seems ideal for disease manifestation. A dataset of 2,311 soil samples from commercial farms assessed from 2002 to 2015 allowed us to evaluate the environmental conditions associated with the pathogen's optimum inoculum density for disease occurrence, using a lower threshold as a spatial proxy. We encompassed not only the optimal conditions for disease occurrence but also the optimal pathogen's density required for host infection. An intermediate inoculum density of the pathogen was the best disease proxy, suggesting density-dependent mechanisms on host infection. We found a strong convergence on the environmental requirements of both the host and the disease development in tropical areas, mostly in Brazil, Central America, and African countries. Precipitation and temperature variables were important for explaining the disease occurrence (from 17.63% to 43.84%). Climate change will probably move the disease toward cooler regions, which in Brazil are more representative of small-scale farming, although an overall shrink in total area (from 48% to 49% in 2050 and 26% to 41% in 2070) was also predicted. Understanding pathogen distribution and disease risks in an evolutionary context will therefore support breeding for resistance programs and strategies for dry root rot management in common beans.

The rotation-powered nature of some soft gamma-ray repeaters and anomalous X-ray pulsars

NASA Astrophysics Data System (ADS)

Coelho, Jaziel G.; Cáceres, D. L.; de Lima, R. C. R.; Malheiro, M.; Rueda, J. A.; Ruffini, R.

2017-03-01

Context. Soft gamma-ray repeaters (SGRs) and anomalous X-ray pulsars (AXPs) are slow rotating isolated pulsars whose energy reservoir is still matter of debate. Adopting neutron star (NS) fiducial parameters; mass M = 1.4 M⊙, radius R = 10 km, and moment of inertia, I = 1045 g cm2, the rotational energy loss, Ėrot, is lower than the observed luminosity (dominated by the X-rays) LX for many of the sources. Aims: We investigate the possibility that some members of this family could be canonical rotation-powered pulsars using realistic NS structure parameters instead of fiducial values. Methods: We compute the NS mass, radius, moment of inertia and angular momentum from numerical integration of the axisymmetric general relativistic equations of equilibrium. We then compute the entire range of allowed values of the rotational energy loss, Ėrot, for the observed values of rotation period P and spin-down rate Ṗ. We also estimate the surface magnetic field using a general relativistic model of a rotating magnetic dipole. Results: We show that realistic NS parameters lowers the estimated value of the magnetic field and radiation efficiency, LX/Ėrot, with respect to estimates based on fiducial NS parameters. We show that nine SGRs/AXPs can be described as canonical pulsars driven by the NS rotational energy, for LX computed in the soft (2-10 keV) X-ray band. We compute the range of NS masses for which LX/Ėrot< 1. We discuss the observed hard X-ray emission in three sources of the group of nine potentially rotation-powered NSs. This additional hard X-ray component dominates over the soft one leading to LX/Ėrot > 1 in two of them. Conclusions: We show that 9 SGRs/AXPs can be rotation-powered NSs if we analyze their X-ray luminosity in the soft 2-10 keV band. Interestingly, four of them show radio emission and six have been associated with supernova remnants (including Swift J1834.9-0846 the first SGR observed with a surrounding wind nebula). These observations give additional support to our results of a natural explanation of these sources in terms of ordinary pulsars. Including the hard X-ray emission observed in three sources of the group of potential rotation-powered NSs, this number of sources with LX/Ėrot< 1 becomes seven. It remains open to verification 1) the accuracy of the estimated distances and 2) the possible contribution of the associated supernova remnants to the hard X-ray emission.

Allozyme-Specific Modification of a Maize Seed Chitinase by a Protein Secreted by the Fungal Pathogen Stenocarpella maydis

USDA-ARS?s Scientific Manuscript database

Stenocarpella maydis causes both dry-ear rot and stalk rot of maize. Maize inbreds have varying levels of resistance to S. maydis ear rot. The genetic basis of resistance appears to rely on multiple genetic factors, none of which are known. The commonly used stiff stalk inbred B73 has been shown ...

QTL mapping of fruit rot resistance to the plant pathogen Phytophthora capsici in a recombinant inbred line Capsicum annuum population.

PubMed

Naegele, R P; Ashrafi, H; Hill, T A; Chin-Wo, S Reyes; Van Deynze, A E; Hausbeck, M K

2014-05-01

Phytophthora capsici is an important pepper (Capsicum annuum) pathogen causing fruit and root rot, and foliar blight in field and greenhouse production. Previously, an F6 recombinant inbred line population was evaluated for fruit rot susceptibility. Continuous variation among lines and partial and isolate-specific resistance were found. In this study, Phytophthora fruit rot resistance was mapped in the same F6 population between Criollo del Morelos 334 (CM334), a landrace from Mexico, and 'Early Jalapeno' using a high-density genetic map. Isolate-specific resistance was mapped independently in 63 of the lines evaluated and the two parents. Heritability of the resistance for each isolate at 3 and 5 days postinoculation (dpi) was high (h(2) = 0.63 to 0.68 and 0.74 to 0.83, respectively). Significant additive and epistatic quantitative trait loci (QTL) were identified for resistance to isolates OP97 and 13709 (3 and 5 dpi) and 12889 (3 dpi only). Mapping of fruit traits showed potential linkage with few disease resistance QTL. The partial fruit rot resistance from CM334 suggests that this may not be an ideal source for fruit rot resistance in pepper.

Resistance to toxin-mediated fungal infection: role of lignins, isoflavones, other seed phenolics, sugars and boron in the mechanism of resistance to charcoal rot disease in soybean

USDA-ARS?s Scientific Manuscript database

The objective of this research was to investigate the combined effects of charcoal rot and drought on total seed phenol, isoflavones, sugars, and boron in susceptible (S) and moderately resistant (MR) soybean genotypes to charcoal rot pathogen. A field experiment was conducted for two years under ir...

Interaction of Pratylenchus penetrans and Rhizoctonia fragariae in Strawberry Black Root Rot

PubMed Central

LaMondia, J. A.

2003-01-01

A split-root technique was used to examine the interaction between Pratylenchus penetrans and the cortical root-rotting pathogen Rhizoctonia fragariae in strawberry black root rot. Plants inoculated with both pathogens on the same half of a split-root crown had greater levels of root rot than plants inoculated separately or with either pathogen alone. Isolation of R. fragariae from field-grown roots differed with root type and time of sampling. Fungal infection of structural roots was low until fruiting, whereas perennial root colonization was high. Isolation of R. fragariae from feeder roots was variable, but was greater from feeder roots on perennial than from structural roots. Isolation of the fungus was greater from structural roots with nematode lesions than from non-symptomatic roots. Rhizoctonia fragariae was a common resident on the sloughed cortex of healthy perennial roots. From this source, the fungus may infect additional roots. The direct effects of lesion nematode feeding and movement are cortical cell damage and death. Indirect effects include discoloration of the endodermis and early polyderm formation. Perhaps weakened or dying cells caused directly or indirectly by P. penetrans are more susceptible to R. fragariae, leading to increased disease. PMID:19265969

Rice-Infecting Pseudomonas Genomes Are Highly Accessorized and Harbor Multiple Putative Virulence Mechanisms to Cause Sheath Brown Rot.

PubMed

Quibod, Ian Lorenzo; Grande, Genelou; Oreiro, Eula Gems; Borja, Frances Nikki; Dossa, Gerbert Sylvestre; Mauleon, Ramil; Cruz, Casiana Vera; Oliva, Ricardo

2015-01-01

Sheath rot complex and seed discoloration in rice involve a number of pathogenic bacteria that cannot be associated with distinctive symptoms. These pathogens can easily travel on asymptomatic seeds and therefore represent a threat to rice cropping systems. Among the rice-infecting Pseudomonas, P. fuscovaginae has been associated with sheath brown rot disease in several rice growing areas around the world. The appearance of a similar Pseudomonas population, which here we named P. fuscovaginae-like, represents a perfect opportunity to understand common genomic features that can explain the infection mechanism in rice. We showed that the novel population is indeed closely related to P. fuscovaginae. A comparative genomics approach on eight rice-infecting Pseudomonas revealed heterogeneous genomes and a high number of strain-specific genes. The genomes of P. fuscovaginae-like harbor four secretion systems (Type I, II, III, and VI) and other important pathogenicity machinery that could probably facilitate rice colonization. We identified 123 core secreted proteins, most of which have strong signatures of positive selection suggesting functional adaptation. Transcript accumulation of putative pathogenicity-related genes during rice colonization revealed a concerted virulence mechanism. The study suggests that rice-infecting Pseudomonas causing sheath brown rot are intrinsically diverse and maintain a variable set of metabolic capabilities as a potential strategy to occupy a range of environments.

Aggressiveness of Fusarium species and impact of root infection on growth and yield of soybeans.

PubMed

Arias, María M Díaz; Leandro, Leonor F; Munkvold, Gary P

2013-08-01

Fusarium spp. are commonly isolated from soybean roots but the pathogenic activity of most species is poorly documented. Aggressiveness and yield impact of nine species of Fusarium were determined on soybean in greenhouse (50 isolates) and field microplot (19 isolates) experiments. Root rot severity and shoot and root dry weights were compared at growth stages V3 or R1. Root systems were scanned and digital image analysis was conducted; yield was measured in microplots. Disease severity and root morphology impacts varied among and within species. Fusarium graminearum was highly aggressive (root rot severity >90%), followed by F. proliferatum and F. virguliforme. Significant variation in damping-off (20 to 75%) and root rot severity (<20 to >60%) was observed among F. oxysporum isolates. In artificially-infested microplots, root rot severity was low (<25%) and mean yield was not significantly reduced. However, there were significant linear relationships between yield and root symptoms for some isolates. Root morphological characteristics were more consistent indicators of yield loss than root rot severity. This study provides the first characterization of aggressiveness and yield impact of Fusarium root rot species on soybean at different plant stages and introduces root image analysis to assess the impact of root pathogens on soybean.

Co-Inoculation with Rhizobia and AMF Inhibited Soybean Red Crown Rot: From Field Study to Plant Defense-Related Gene Expression Analysis

PubMed Central

Gao, Xiang; Lu, Xing; Wu, Man; Zhang, Haiyan; Pan, Ruqian; Tian, Jiang; Li, Shuxian; Liao, Hong

2012-01-01

Background Soybean red crown rot is a major soil-borne disease all over the world, which severely affects soybean production. Efficient and sustainable methods are strongly desired to control the soil-borne diseases. Principal Findings We firstly investigated the disease incidence and index of soybean red crown rot under different phosphorus (P) additions in field and found that the natural inoculation of rhizobia and arbuscular mycorrhizal fungi (AMF) could affect soybean red crown rot, particularly without P addition. Further studies in sand culture experiments showed that inoculation with rhizobia or AMF significantly decreased severity and incidence of soybean red crown rot, especially for co-inoculation with rhizobia and AMF at low P. The root colony forming unit (CFU) decreased over 50% when inoculated by rhizobia and/or AMF at low P. However, P addition only enhanced CFU when inoculated with AMF. Furthermore, root exudates of soybean inoculated with rhizobia and/or AMF significantly inhibited pathogen growth and reproduction. Quantitative RT-PCR results indicated that the transcripts of the most tested pathogen defense-related (PR) genes in roots were significantly increased by rhizobium and/or AMF inoculation. Among them, PR2, PR3, PR4 and PR10 reached the highest level with co-inoculation of rhizobium and AMF. Conclusions Our results indicated that inoculation with rhizobia and AMF could directly inhibit pathogen growth and reproduction, and activate the plant overall defense system through increasing PR gene expressions. Combined with optimal P fertilization, inoculation with rhizobia and AMF could be considered as an efficient method to control soybean red crown rot in acid soils. PMID:22442737

Fine-Scale Genetic Structure of Monilinia fructicola During Brown Rot Epidemics Within Individual Peach Tree Canopies.

PubMed

Everhart, S E; Scherm, H

2015-04-01

The purpose of this study was to determine the fine-scale genetic structure of populations of the brown rot pathogen Monilinia fructicola within individual peach tree canopies to better understand within-tree plant pathogen diversity and to complement previous work on spatiotemporal development of brown rot disease at the canopy level. Across 3 years in a total of six trees, we monitored disease development, collected isolates from every M. fructicola symptom during the course of the season, and created high-resolution three-dimensional maps of all symptom and isolate locations within individual canopies using an electromagnetic digitizer. Each canopy population (65 to 173 isolates per tree) was characterized using a set of 13 microsatellite markers and analyzed for evidence of spatial genetic autocorrelation among isolates during the epidemic phase of the disease. Results showed high genetic diversity (average uh=0.529) and high genotypic diversity (average D=0.928) within canopies. The percentage of unique multilocus genotypes within trees was greater for blossom blight isolates (78.2%) than for fruit rot isolates (51.3%), indicating a greater contribution of clonal reproduction during the preharvest epidemic. For fruit rot isolates, between 54.2 and 81.7% of isolates were contained in one to four dominant clonal genotypes per tree having at least 10 members. All six fruit rot populations showed positive and significant spatial genetic autocorrelation for distance classes between 0.37 and 1.48 m. Despite high levels of within-tree pathogen diversity, the contribution of locally available inoculum combined with short-distance dispersal is likely the main factor generating clonal population foci and associated spatial genetic clustering within trees.

Cacao diseases: A history of old enemies and new encounters

USDA-ARS?s Scientific Manuscript database

This book reviews the current knowledge of cacao pathogens and their management methods. Topics discussed include the history, biology, and genetic diversity of Moniliophthora (causing witches’ broom and frosty pod rot) and Phytophthora species (causing black pod rot) that cause diseases resulting i...

Pre-Breeding for root rot resistance using root morphology traits

USDA-ARS?s Scientific Manuscript database

Root rot caused by the fungal pathogen Rhizoctonia solani can be a major yield-limiting disease in minimal tillage or direct-seeded cereal production systems. Reduced tillage greatly influences the plant residue retained on the soil surfaces. This retained residue (green bridge) provides increased d...

Host resistance to phytophthora fruit rot in U.S. watermelon plant introductions

USDA-ARS?s Scientific Manuscript database

Phytophthora capsici, distributed worldwide, is an aggressive pathogen with a broad host range, infecting solanaceous, leguminaceous, and cucurbitaceous crops. Phytophthora fruit rot of watermelon (Citrullus lanatus) caused by P. capsici was first reported in the U.S. in 1940. Since then, the dise...

Integrated options for the management of black root rot of strawberry caused by Rhizoctonia solani Kuhn.

PubMed

Asad-Uz-Zaman, Md; Bhuiyan, Mohammad Rejwan; Khan, Mohammad Ashik Iqbal; Alam Bhuiyan, Md Khurshed; Latif, Mohammad Abdul

2015-02-01

An investigation was made to manage strawberry black root rot caused by Rhizoctonia solani (R. solani) through the integration of Trichoderma harzianum (T. harzianum) isolate STA7, mustard oil cake and Provax 200. A series of preliminary experiments were conducted to select a virulent isolate of R. solani, an effective isolate of T. harzianum, a suitable organic amendment, and a suitable fungicide before setting the experiment for integration. The pathogenicity of the selected four isolates of R. solani was evaluated against strawberry and isolate SR1 was selected as the test pathogen due to its highest virulent (95.47% mortality) characteristics. Among the 20 isolates of T. harzianum, isolate STA7 showed maximum inhibition (71.97%) against the test pathogen (R. solani). Among the fungicides, Provax-200 was found to be more effective at lowest concentration (100 ppm) and highly compatible with Trichoderma isolates STA7. In the case of organic amendments, maximum inhibition (59.66%) of R. solani was obtained through mustard oil cake at the highest concentration (3%), which was significantly superior to other amendments. Minimum percentages of diseased roots were obtained with pathogen (R. solani)+Trichoderma+mustard oil cake+Provax-200 treatment, while the highest was observed with healthy seedlings with a pathogen-inoculated soil. In the case of leaf and fruit rot diseases, significantly lowest infected leaves as well as fruit rot were observed with a pathogen+Trichoderma+mustard oil cake+Provax-200 treatment in comparison with the control. A similar trend of high effectiveness was observed by the integration of Trichoderma, fungicide and organic amendments in controlling root rot and fruit diseases of strawberry. Single application of Trichoderma isolate STA7, Provax 200 or mustard oil cake did not show satisfactory performance in terms of disease-free plants, but when they were applied in combination, the number of healthy plants increased significantly. The result of the current study suggests the superiority of our integrated approach to control the sclerotia forming pathogen R. solani compared to the individual treatment either by an antagonist or by a fungicide or by mustard oil cake. Copyright © 2014 Académie des sciences. Published by Elsevier SAS. All rights reserved.

Draft whole genome sequence of groundnut stem rot fungus Athelia rolfsii revealing genetic architect of its pathogenicity and virulence.

PubMed

Iquebal, M A; Tomar, Rukam S; Parakhia, M V; Singla, Deepak; Jaiswal, Sarika; Rathod, V M; Padhiyar, S M; Kumar, Neeraj; Rai, Anil; Kumar, Dinesh

2017-07-13

Groundnut (Arachis hypogaea L.) is an important oil seed crop having major biotic constraint in production due to stem rot disease caused by fungus, Athelia rolfsii causing 25-80% loss in productivity. As chemical and biological combating strategies of this fungus are not very effective, thus genome sequencing can reveal virulence and pathogenicity related genes for better understanding of the host-parasite interaction. We report draft assembly of Athelia rolfsii genome of ~73 Mb having 8919 contigs. Annotation analysis revealed 16830 genes which are involved in fungicide resistance, virulence and pathogenicity along with putative effector and lethal genes. Secretome analysis revealed CAZY genes representing 1085 enzymatic genes, glycoside hydrolases, carbohydrate esterases, carbohydrate-binding modules, auxillary activities, glycosyl transferases and polysaccharide lyases. Repeat analysis revealed 11171 SSRs, LTR, GYPSY and COPIA elements. Comparative analysis with other existing ascomycotina genome predicted conserved domain family of WD40, CYP450, Pkinase and ABC transporter revealing insight of evolution of pathogenicity and virulence. This study would help in understanding pathogenicity and virulence at molecular level and development of new combating strategies. Such approach is imperative in endeavour of genome based solution in stem rot disease management leading to better productivity of groundnut crop in tropical region of world.

Transgenic plants producing the bacterial pheromone N-acyl-homoserine lactone exhibit enhanced resistance to the bacterial phytopathogen Erwinia carotovora.

PubMed

Mäe, A; Montesano, M; Koiv, V; Palva, E T

2001-09-01

Bacterial pheromones, mainly different homoserine lactones, are central to a number of bacterial signaling processes, including those involved in plant pathogenicity. We previously demonstrated that N-oxoacyl-homoserine lactone (OHL) is essential for quorum sensing in the soft-rot phytopathogen Erwinia carotovora. In this pathogen, OHL controls the coordinate activation of genes encoding the main virulence determinants, extracellular plant cell wall degrading enzymes (PCWDEs), in a cell density-dependent manner. We suggest that E. carotovora employ quorum sensing to avoid the premature production of PCWDEs and subsequent activation of plant defense responses. To test whether modulating this sensory system would affect the outcome of a plant-pathogen interaction, we generated transgenic tobacco, producing OHL. This was accomplished by ectopic expression in tobacco of the E. carotovora gene expI, which is responsible for OHL biosynthesis. We show that expI-positive transgenic tobacco lines produced the active pheromone and partially complemented the avirulent phenotype of expI mutants. The OHL-producing tobacco lines exhibited enhanced resistance to infection by wild-type E. carotovora. The results were confirmed by exogenous addition of OHL to wild-type plants, which also resulted in increased resistance to E. carotovora.

Development of molecular methods to detect Macrophomina phaseolina from strawberry plants and soil

USDA-ARS?s Scientific Manuscript database

Macrophomina phaseolina is a broad-host range fungus that shows some degree of host preference on strawberry, and causes symptoms including charcoal rot and root rot. Recently, this pathogen has impacted strawberry production as fumigation practices have changed, leaving many growers in California a...

Antibacterial activity of plant defensins against alfalfa crown rot pathogens

USDA-ARS?s Scientific Manuscript database

Alfalfa (Medicago sativa) is the fourth most widely grown crop in the United States. Alfalfa crown rot is a disease complex that severely decreases alfalfa stand density and productivity in all alfalfa-producing areas. Currently, there are no viable methods of disease control. Plant defensins are sm...

Heroes and villains: Research identifies harmful and beneficial microbes in nursery soil

USDA-ARS?s Scientific Manuscript database

Phytophthora and Pythium species are common pathogens in nursery systems that can cause rhododendron root rot. Plants with root rot are often stunted, and may wilt and die, thus directly reducing nursery profit. Rhododendrons are an important crop in Pacific Northwest nurseries, but are highly susc...

Loop-mediated isothermal amplification (LAMP) based detection of Colletotrichum falcatum causing red rot in sugarcane

USDA-ARS?s Scientific Manuscript database

Red rot, caused by Colletotrichum falcatum, is a destructive disease prevalent in most sugarcane-producing countries. Disease-free sugarcane planting materials are essential as the pathogen spreads primarily through infected setts. The present study was undertaken to develop loop-mediated isothermal...

Endophytic and pathogenic fungi of developing cranberry ovaries from flower to mature fruit: diversity and succession

USDA-ARS?s Scientific Manuscript database

Culturable fungal population diversity and succession were investigated in developing cranberry ovaries of fruit rot-resistant and rot-susceptible cranberry selections, from flower through mature fruit. Fungi were recovered in culture from 1185 of 1338 ovary tissues collected from June to September,...

Black pod: diverse pathogens with a global impact on cocoa yield.

PubMed

Guest, David

2007-12-01

ABSTRACT Pathogens of the Straminipile genus Phytophthora cause significant disease losses to global cocoa production. P. megakarya causes significant pod rot and losses due to canker in West Africa, whereas P. capsici and P. citrophthora cause pod rots in Central and South America. The global and highly damaging P. palmivora attacks all parts of the cocoa tree at all stages of the growing cycle. This pathogen causes 20 to 30% pod losses through black pod rot, and kills up to 10% of trees annually through stem cankers. P. palmivora has a complex disease cycle involving several sources of primary inoculum and several modes of dissemination of secondary inoculum. This results in explosive epidemics during favorable environmental conditions. The spread of regional pathogens must be prevented by effective quarantine barriers. Resistance to all these Phytophthora species is typically low in commercial cocoa genotypes. Disease losses can be reduced through integrated management practices that include pruning and shade management, leaf mulching, regular and complete harvesting, sanitation and pod case disposal, appropriate fertilizer application and targeted fungicide use. Packaging these options to improve uptake by smallholders presents a major challenge for the industry.

Characterization of the Maize Stalk Rot Pathogens Fusarium subglutinans and F. temperatum and the Effect of Fungicides on Their Mycelial Growth and Colony Formation

PubMed Central

Shin, Jong-Hwan; Han, Joon-Hee; Lee, Ju Kyong; Kim, Kyoung Su

2014-01-01

Maize is a socioeconomically important crop in many countries. Recently, a high incidence of stalk rot disease has been reported in several maize fields in Gangwon province. In this report, we show that maize stalk rot is associated with the fungal pathogens Fusarium subglutinans and F. temperatum. Since no fungicides are available to control these pathogens on maize plants, we selected six fungicides (tebuconazole, difenoconazole, fluquinconazole, azoxystrobin, prochloraz and kresoxim-methyl) and examined their effectiveness against the two pathogens. The in vitro antifungal effects of the six fungicides on mycelial growth and colony formation were investigated. Based on the inhibition of mycelial growth, the most toxic fungicide was tebuconazole with 50% effective concentrations (EC50) of <0.1 μg/ml and EC90 values of 0.9 μg/ml for both pathogens, while the least toxic fungicide was azoxystrobin with EC50 values of 0.7 and 0.5 μg/ml for F. subglutinans and F. temperatum, respectively, and EC90 values of >3,000 μg/ml for both pathogens. Based on the inhibition of colony formation by the two pathogens, kresoxim-methyl was the most toxic fungicide with complete inhibition of colony formation at concentrations of 0.1 and 0.01 μg/ml for F. subglutinans and F. temperatum, respectively, whereas azoxystrobin was the least toxic fungicide with complete inhibition of colony formation at concentrations >3,000 μg/ml for both pathogens. PMID:25506304

First Report of Sclerotium Rot on Cymbidium Orchids Caused by Sclerotium rolfsii in Korea

PubMed Central

Lee, Seong-Chan; Lee, Jung-Sup; Soh, Jae-Woo; Kim, Su

2012-01-01

Sclerotium rot was found on Cymbidium orchids at Seosan-si, Chungcheongnam-do, Korea, in July, 2010. Symptoms occurred on low leaves, which turned yellowish, after which the entire plant wilted. Severely infected plants were blighted and eventually died. White mycelial mats and sclerotia appeared on pseudobulbs. Based on the mycological characteristics and pathogenicity, the causal fungus was identified as Sclerotium rolfsii. This is the first report of new Sclerotium rot on Cymbidium spp. caused by S. rolfsii in Korea. PMID:23323053

Wide variation in virulence and genetic diversity of binucleate Rhizoctonia isolates associated with root rot of strawberry in Western Australia.

PubMed

Fang, Xiangling; Finnegan, Patrick M; Barbetti, Martin J

2013-01-01

Strawberry (Fragaria×ananassa) is one of the most important berry crops in the world. Root rot of strawberry caused by Rhizoctonia spp. is a serious threat to commercial strawberry production worldwide. However, there is no information on the genetic diversity and phylogenetic status of Rhizoctonia spp. associated with root rot of strawberry in Australia. To address this, a total of 96 Rhizoctonia spp. isolates recovered from diseased strawberry plants in Western Australia were characterized for their nuclear condition, virulence, genetic diversity and phylogenetic status. All the isolates were found to be binucleate Rhizoctonia (BNR). Sixty-five of the 96 BNR isolates were pathogenic on strawberry, but with wide variation in virulence, with 25 isolates having high virulence. Sequence analysis of the internal transcribed spacers of the ribosomal DNA separated the 65 pathogenic BNR isolates into six distinct clades. The sequence analysis also separated reference BNR isolates from strawberry or other crops across the world into clades that correspond to their respective anastomosis group (AG). Some of the pathogenic BNR isolates from this study were embedded in the clades for AG-A, AG-K and AG-I, while other isolates formed clades that were sister to the clades specific for AG-G, AG-B, AG-I and AG-C. There was no significant association between genetic diversity and virulence of these BNR isolates. This study demonstrates that pathogenic BNR isolates associated with root rot of strawberry in Western Australia have wide genetic diversity, and highlights new genetic groups not previously found to be associated with root rot of strawberry in the world (e.g., AG-B) or in Australia (e.g., AG-G). The wide variation in virulence and genetic diversity identified in this study will be of high value for strawberry breeding programs in selecting, developing and deploying new cultivars with resistance to these multi-genetic groups of BNR.

Potential worldwide distribution of Fusarium dry root rot in common beans based on the optimal environment for disease occurrence

PubMed Central

Macedo, Renan; Sales, Lilian Patrícia; Yoshida, Fernanda; Silva-Abud, Lidianne Lemes

2017-01-01

Root rots are a constraint for staple food crops and a long-lasting food security problem worldwide. In common beans, yield losses originating from root damage are frequently attributed to dry root rot, a disease caused by the Fusarium solani species complex. The aim of this study was to model the current potential distribution of common bean dry root rot on a global scale and to project changes based on future expectations of climate change. Our approach used a spatial proxy of the field disease occurrence, instead of solely the pathogen distribution. We modeled the pathogen environmental requirements in locations where in-situ inoculum density seems ideal for disease manifestation. A dataset of 2,311 soil samples from commercial farms assessed from 2002 to 2015 allowed us to evaluate the environmental conditions associated with the pathogen’s optimum inoculum density for disease occurrence, using a lower threshold as a spatial proxy. We encompassed not only the optimal conditions for disease occurrence but also the optimal pathogen’s density required for host infection. An intermediate inoculum density of the pathogen was the best disease proxy, suggesting density-dependent mechanisms on host infection. We found a strong convergence on the environmental requirements of both the host and the disease development in tropical areas, mostly in Brazil, Central America, and African countries. Precipitation and temperature variables were important for explaining the disease occurrence (from 17.63% to 43.84%). Climate change will probably move the disease toward cooler regions, which in Brazil are more representative of small-scale farming, although an overall shrink in total area (from 48% to 49% in 2050 and 26% to 41% in 2070) was also predicted. Understanding pathogen distribution and disease risks in an evolutionary context will therefore support breeding for resistance programs and strategies for dry root rot management in common beans. PMID:29107985

pH-Dependent DNA Distortion and Repression of Gene Expression by Pectobacterium atrosepticum PecS.

PubMed

Deochand, Dinesh K; Meariman, Jacob K; Grove, Anne

2016-07-15

Transcriptional activity is exquisitely sensitive to changes in promoter DNA topology. Transcription factors may therefore control gene activity by modulating the relative positioning of -10 and -35 promoter elements. The plant pathogen Pectobacterium atrosepticum, which causes soft rot in potatoes, must alter gene expression patterns to ensure growth in planta. In the related soft-rot enterobacterium Dickeya dadantii, PecS functions as a master regulator of virulence gene expression. Here, we report that P. atrosepticum PecS controls gene activity by altering promoter DNA topology in response to pH. While PecS binds the pecS promoter with high affinity regardless of pH, it induces significant DNA distortion only at neutral pH, the pH at which the pecS promoter is repressed in vivo. At pH ∼8, DNA distortions are attenuated, and PecS no longer represses the pecS promoter. A specific histidine (H142) located in a crevice between the dimerization- and DNA-binding regions is required for pH-dependent changes in DNA distortion and repression of gene activity, and mutation of this histidine renders the mutant protein incapable of repressing the pecS promoter. We propose that protonated PecS induces a DNA conformation at neutral pH in which -10 and -35 promoter elements are suboptimally positioned for RNA polymerase binding; on deprotonation of PecS, binding is no longer associated with significant changes in DNA conformation, allowing gene expression. We suggest that this mode of gene regulation leads to differential expression of the PecS regulon in response to alkalinization of the plant apoplast.

First report of Gliocephalotrichum bulbilium and G. simplex causing fruit rot of rambutan in Puerto Rico

USDA-ARS?s Scientific Manuscript database

Worldwide, significant post-harvest disease losses of rambutan (Nephelium lappaceum L.) have been reported and several pathogens have been associated with fruit rot. Even though rambutan was introduced to Puerto Rico in 1927, it was not until 1998 that commercial farms were established in the wester...

Pythium species causing damping-off of alfalfa in Minnesota: Identification, pathogenicity and fungicide sensitivity

USDA-ARS?s Scientific Manuscript database

Damping-off and seed rot is an important disease of alfalfa, severely affecting stand establishment when conditions favor the disease. Globally, 15 Pythium species are reported to cause damping-off and seed rot of alfalfa, although surveys of species causing disease on alfalfa in Minnesota are lacki...

Irrigation affects severity of root rot caused by Phythophthora plurivora and P. cinnamomi on rhododendron

USDA-ARS?s Scientific Manuscript database

Plant pathogens in the genus Phytophthora cause root rot that decrease product quality and result in plant death and economic losses to the nursery industry. Recently, we found Phytophthora plurivora prevalent on rhododendron in nurseries in the Pacific Northwest, USA, but there is little informatio...

Acid and neutral trehalase activities in mutants of the corn rot fungus Fusarium verticillioides

USDA-ARS?s Scientific Manuscript database

Fusarium verticillioides is a fungal pathogen known to cause corn rot and other plant diseases and to contaminate grain with toxic metabolites. We are characterizing trehalose metabolism in F. verticillioides with the hope that this pathway might serve as a target for controlling Fusarium disease. T...

Responses to recurrent index selection for reduced fusarium ear rot and lodging and for increased yield in maize

USDA-ARS?s Scientific Manuscript database

Fusarium ear rot caused by the pathogen Fusarium verticillioides (Sacc.) Nirenberg damages maize (Zea mays L.) grain production and is associated with contamination of grain by fumonisin, a mycotoxin harmful to both humans and animals. Recurrent selection may be an effective way to combine improveme...

QTL analysis of Fusarium root rot resistance in an Andean x Middle American common bean RIL population

USDA-ARS?s Scientific Manuscript database

Aims Fusarium root rot (FRR) is a soil-borne disease that constrains common bean (Phaseolus vulgaris L.) production. FRR causal pathogens include clade 2 members of the Fusarium solani species complex. Here we characterize common bean reaction to four Fusarium species and identify genomic regions as...

Maize chiA as a Potential Genetic Marker for Stenocarpella maydis Ear Rot Resistance

USDA-ARS?s Scientific Manuscript database

Stenocarpella maydis (Diplodia maydis) is the most prevalent ear rot pathogen in nearly all countries where maize is produced. The genetic basis of plant resistance to S. maydis appears to rely on multiple genetic factors, none of which are known. We previously reported that S. maydis secretes a p...

Seed treatment with live or dead Fusarium verticillioides equivalently reduces the severity of subsequent stalk rot

USDA-ARS?s Scientific Manuscript database

Fusarium verticillioides is a widely distributed fungus that can associate with maize as a deleterious pathogen and an advantageous endophyte. Here, we show that seed treatment with live F.verticillioides enhances maize resistance to secondary stalk rot infection, and demonstrate that dead F.vertici...

Control of Root Rot and Wilt Diseases of Roselle under Field Conditions

PubMed Central

Hassan, Naglaa; Elsharkawy, Mohsen Mohamed; Shimizu, Masafumi

2014-01-01

Roselle (Hibiscus sabdariffa L.) is one of the most important medicinal crops in many parts of the world. In this study, the effects of microelements, antioxidants, and bioagents on Fusarium oxysporum, F. solani, and Macrophomina phaseolina, the causal pathogens of root rot and wilt diseases in roselle, were examined under field conditions. Preliminary studies were carried out in vitro in order to select the most effective members to be used in field control trials. Our results showed that microelements (copper and manganese), antioxidants (salicylic acid, ascorbic acid, and EDTA), a fungicide (Dithane M45) and biological control agents (Trichoderma harzianum and Bacillus subtilis) were significantly reduced the linear growth of the causal pathogens. Additionally, application of the previous microelements, antioxidants, a fungicide and biological control agents significantly reduced disease incidence of root rot and wilt diseases under field conditions. Copper, salicylic acid, and T. harzianum showed the best results in this respect. In conclusion, microelements, antioxidants, and biocontrol agents could be used as alternative strategies to fungicides for controlling root rot and wilt diseases in roselle. PMID:25606010

Antioxidant defense response induced by Trichoderma viride against Aspergillus niger Van Tieghem causing collar rot in groundnut (Arachis hypogaea L.).

PubMed

Gajera, H P; Katakpara, Zinkal A; Patel, S V; Golakiya, B A

2016-02-01

The study was conducted to examine the antioxidant enzymes induced by Trichoderma viride JAU60 as initial defense response during invasion of rot pathogen Aspergillus niger Van Tieghem in five groundnut varieties under pot culture. Seed treatment of T. viride JAU60 reduced 51-58% collar rot disease incidence in different groundnut varieties under pathogen infected soil culture. The activities of the antioxidant enzymes, viz., superoxide dismutase (SOD, EC 1.15.1.1), guaiacol peroxidase (GPX, EC 1.11.1.7) and ascorbate peroxidase (APX, EC 1.11.1.11), elevated in response to pathogen infection, in higher rate by tolerant varieties (J-11 and GG-2) compared with susceptible (GAUG-10, GG-13, GG-20) and further induced by T. viride treatment. Trichoderma treatment remarkably increased the 2.3 fold SOD, 5 fold GPX and 2.5 fold APX activities during disease development in tolerant varieties and the same was found about 1.2, 1.5 and 2.0 folds, respectively, in susceptible varieties. Overall, T. viride JAU60 treated seedlings (T3) witnessed higher activities of SOD (1.5 fold), GPX (3.25 fold) and APX (1.25 fold) than pathogen treatment (T2) possibly suggest the induction of antioxidant defense response by Trichoderma bio-controller to combat oxidative burst produced by invading pathogen. Copyright © 2015 Elsevier Ltd. All rights reserved.

Genomic characteristics of vB_PpaP_PP74, a T7-like Autographivirinae bacteriophage infecting a potato pathogen of the newly proposed species Pectobacterium parmentieri.

PubMed

Kabanova, Anastasia; Shneider, Mikhail; Bugaeva, Eugenia; Ha, Vo Thi Ngoc; Miroshnikov, Kirill; Korzhenkov, Aleksei; Kulikov, Eugene; Toschakov, Stepan; Ignatov, Alexander; Miroshnikov, Konstantin

2018-06-01

Bacteriophage vB_PpaP_PP74 (PP74) is a novel virulent phage that infects members of the species Pectobacterium parmentieri, a newly established species of soft-rot-causing bacteria in the family Pectobacteriaceae, derived from potato-specific Pectobacterium wasabiae. vB_PpaP_PP74 was identified as a member of the family Podoviridae by transmission electron microscopy. The phage has a 39,790-bp dsDNA genome containing 50 open reading frames (ORFs). Because of the absence of genes encoding toxins or lysogeny factors, PP74 may be considered a candidate phage for pathogen biocontrol applications. The genome layout is similar to genomes of T7-like phages within the subfamily Autographivirinae, and therefore, functions can be attributed to most of ORFs. However, the closest nucleotide sequence homologs of phage PP74 are unclassified Escherichia phages. Based on phylogenetic analysis, vB_PpaP_PP74 is a sensu lato T7-like phage, but it forms a distant subgenus group together with homologous enterobacterial phages.

Wood digestion in Pselactus spadix Herbst--a weevil attacking marine timber structures.

PubMed

Oevering, Pascal; Pitman, Andrew J; Pandey, Krishna K

2003-04-01

Pselactus spadix tunnels timber structures in the marine environment. Recent studies reported a cosmopolitan distribution for this weevil, which is frequently found in harbour and port areas. P. spadix feeds on timber (hardwood and softwood) in immature and adult life stages, but its digestion of wood components had not been investigated. Using dry weight analyses of tunnel walls and frass produced, P. spadix adults consumed Scots pine with soft rot decay at a rate of 1.59 +/- 0.37 mg d-1 and the digestibility of this substrate was 57.96 +/- 5.89 (i.e. for 100 mg consumed SR-pine, 58 mg was digested). Using gravimetric analysis to quantify structural wood components in tunnel walls and frass, P. spadix adults were found to digest cellulose, lignin and hemicellulose with digestibility coefficients of 82.2, 41.2 and 14.5 respectively. Fourier Transform Infrared (FTIR) spectroscopy analyses of tunnel walls and frass of adults and larvae from soft rotted pine also indicated digestion of all structural components, with larvae digesting cellulose and lignin more efficiently than adults. When FTIR was employed to analyse adult tunnel walls and frass from undecayed pine, cellulose and hemicellulose were digested, but no evidence of lignin digestion was found. This study shows that adults digest lignin when soft rot is present and suggests a symbiotic function of wood degrading microorganisms.

Laminated Root Rot of Western Conifers

Treesearch

E.E. Nelson; N.E. Martin; R.E. Williams

1981-01-01

Laminated root rot is caused by the native fungus Phellinus weirii (Murr.) Gilb. It occurs throughout the Northwestern United States and in southern British Columbia, Canada. The disease has also been reported in Japan and Manchuria. In the United States, the pathogen is most destructive in pure Douglas-fir stands west of the crest of the Cascade Range in Washington...

Seed rot and damping-off of alfalfa in Minnesota caused by Pythium and Fusarium species

USDA-ARS?s Scientific Manuscript database

Globally, 15 Pythium species have been found to cause damping-off and seed rot of alfalfa, although surveys of species causing disease on alfalfa in the Midwestern U.S. are lacking. Pathogens were isolated by a seedling baiting technique from soil of five alfalfa fields in Minnesota with high levels...

Pathogenicity, fungicide resistance, and genetic variability of Phytophthora rubi isolates from raspberry (Rubus idaeus) in the Western United States

USDA-ARS?s Scientific Manuscript database

Root rot of raspberry (Rubus idaeus), thought to be primarily caused by Phytophthora rubi, is an economically important disease in the western United States. The objectives of this study were to determine which Phytophthora species are involved in root rot, examine the efficacy of different isolatio...

Temporal occurrence and niche preferences of Phytophthora species causing brown rot of citrus in the Central Valley of California

USDA-ARS?s Scientific Manuscript database

Brown rot of citrus fruits is caused by several species of Phytophthora and is currently of serious concern for the California citrus industry. Two species, P. syringae and P. hibernalis, are quarantine pathogens in China, a major export market for California citrus. To maintain trade and estimate t...

Transgenic expression of a maize geranyl geranyl transferase gene sequence in maize callus increases resistance to ear rot pathogens

USDA-ARS?s Scientific Manuscript database

Determining the genes responsible for pest resistance in maize can allow breeders to develop varieties with lower losses and less contamination with undesirable toxins. A gene sequence coding for a geranyl geranyl transferase-like protein located in a fungal ear rot resistance quantitative trait loc...

Spatial patterns of Armillaria populations in the walker branch watershed throughfall displacement experiment, Tennessee,USA.

Treesearch

Johann N. Bruhn; James A. Brenneman; James J., Jr. Wetteroff; Jeanne D. Mihail; Theodor D. Leininger

1997-01-01

Species in the white-rot fungal genus Armillaria vary in parasitic aggressiveness as root and butt rot pathogens of trees. Armillaria genets (individuals) were mapped in the Throughfall Displacement Experiment (TDE) using mushrooms and rhizomorphs collected in 1994 and 1995. Initiated in July 1993, the TDE consists of three 80 x 80...

Population genetic structure and mycotoxin potential of the wheat crown rot and head blight pathogen Fusarium culmorum in Algeria

USDA-ARS?s Scientific Manuscript database

Surveys for crown rot (FCR) and head blight (FHB) of Algerian wheat conducted during 2014 and 2015 revealed that Fusarium culmorum strains producing 3-acetyl-deoxynivalenol (3ADON) or nivalenol (NIV) were the primary causal agents of these important diseases. Morphological identification of the isol...

Temperature, Moisture, and Fungicide Effects in Managing Rhizoctonia Root and Crown Rot of Sugar Beet

USDA-ARS?s Scientific Manuscript database

Rhizoctonia solani AG-2-2 is the causal agent of Rhizoctonia root and crown rot in sugar beet. To assess the capacity at which other anastomosis groups (AGs) are able to infect sugar beet, 15 AGs and subgroups were tested for pathogenicity on resistant (FC708 CMS) and susceptible (Monohikari) seedl...

Fungicide rotation schemes for managing Phytophthora fruit rot of watermelon across Southeastern United States (NC, SC, and GA)

USDA-ARS?s Scientific Manuscript database

Phytophthora capsici has been documented as a pathogen on a wide variety of vegetable crops in the family Solanaceae, Cucurbitaceae, Fabaceae, and plants belonging to 23 other families. Phytophthora fruit rot of watermelons caused by P. capsici is particularly severe in southeastern U.S where optima...

The phytopathogen Dickeya dadantii (Erwinia chrysanthemi 3937) is a pathogen of the pea aphid.

PubMed

Grenier, Anne-Marie; Duport, Gabrielle; Pagès, Sylvie; Condemine, Guy; Rahbé, Yvan

2006-03-01

Dickeya dadantii (Erwinia chrysanthemi) is a phytopathogenic bacterium causing soft rot diseases on many crops. The sequencing of its genome identified four genes encoding homologues of the Cyt family of insecticidal toxins from Bacillus thuringiensis, which are not present in the close relative Pectobacterium carotovorum subsp. atrosepticum. The pathogenicity of D. dadantii was tested on the pea aphid Acyrthosiphon pisum, and the bacterium was shown to be highly virulent for this insect, either by septic injury or by oral infection. The lethal inoculum dose was calculated to be as low as 10 ingested bacterial cells. A D. dadantii mutant with the four cytotoxin genes deleted showed a reduced per os virulence for A. pisum, highlighting the potential role of at least one of these genes in pathogenicity. Since only one bacterial pathogen of aphids has been previously described (Erwinia aphidicola), other species from the same bacterial group were tested. The pathogenic trait for aphids was shown to be widespread, albeit variable, within the phytopathogens, with no link to phylogenetic positioning in the Enterobacteriaceae. Previously characterized gut symbionts from thrips (Erwinia/Pantoea group) were also highly pathogenic to the aphid, whereas the potent entomopathogen Photorhabdus luminescens was not. D. dadantii is not a generalist insect pathogen, since it has low pathogenicity for three other insect species (Drosophila melanogaster, Sitophilus oryzae, and Spodoptera littoralis). D. dadantii was one of the most virulent aphid pathogens in our screening, and it was active on most aphid instars, except for the first one, probably due to anatomical filtering. The observed difference in virulence toward apterous and winged aphids may have an ecological impact, and this deserves specific attention in future research.

RECONSTRUCTING THE EVOLUTIONARY HISTORY OF THE FOREST FUNGAL PATHOGEN, ARMILLARIA MELLEA, IN A TEMPERATE WORLDWIDE POPULATIONS

USDA-ARS?s Scientific Manuscript database

The forest pathogen Armillaria mellea s.s. (Basidiomycota, Physalacriaceae) is among the most significant forest pathogens causing root rot in northern temperate forest trees worldwide. Phylogenetic reconstructions for A. mellea show distinct European, Asian and North American lineages. The North Am...

RNA-mediated Gene Silencing in the Cereal Fungal Pathogen Cochliobolus sativus

USDA-ARS?s Scientific Manuscript database

Cochliobolus sativus (anamorph: Bipolaris sorokiniana) is the causal agent of spot blotch, common root rot and black point in barley and wheat. However, little is known about the mechanisms underlying the pathogenicity and virulence of the pathogen. In this study, we developed a high-throughput RNA-...

Extensive sampling of basidiomycete genomes demonstrates inadequacy of the white-rot/brown-rot paradigm for wood decay fungi

PubMed Central

Riley, Robert; Salamov, Asaf A.; Brown, Daren W.; Nagy, Laszlo G.; Floudas, Dimitrios; Held, Benjamin W.; Levasseur, Anthony; Lombard, Vincent; Morin, Emmanuelle; Otillar, Robert; Lindquist, Erika A.; Sun, Hui; LaButti, Kurt M.; Schmutz, Jeremy; Jabbour, Dina; Luo, Hong; Baker, Scott E.; Pisabarro, Antonio G.; Walton, Jonathan D.; Blanchette, Robert A.; Henrissat, Bernard; Martin, Francis; Cullen, Dan; Hibbett, David S.; Grigoriev, Igor V.

2014-01-01

Basidiomycota (basidiomycetes) make up 32% of the described fungi and include most wood-decaying species, as well as pathogens and mutualistic symbionts. Wood-decaying basidiomycetes have typically been classified as either white rot or brown rot, based on the ability (in white rot only) to degrade lignin along with cellulose and hemicellulose. Prior genomic comparisons suggested that the two decay modes can be distinguished based on the presence or absence of ligninolytic class II peroxidases (PODs), as well as the abundance of enzymes acting directly on crystalline cellulose (reduced in brown rot). To assess the generality of the white-rot/brown-rot classification paradigm, we compared the genomes of 33 basidiomycetes, including four newly sequenced wood decayers, and performed phylogenetically informed principal-components analysis (PCA) of a broad range of gene families encoding plant biomass-degrading enzymes. The newly sequenced Botryobasidium botryosum and Jaapia argillacea genomes lack PODs but possess diverse enzymes acting on crystalline cellulose, and they group close to the model white-rot species Phanerochaete chrysosporium in the PCA. Furthermore, laboratory assays showed that both B. botryosum and J. argillacea can degrade all polymeric components of woody plant cell walls, a characteristic of white rot. We also found expansions in reducing polyketide synthase genes specific to the brown-rot fungi. Our results suggest a continuum rather than a dichotomy between the white-rot and brown-rot modes of wood decay. A more nuanced categorization of rot types is needed, based on an improved understanding of the genomics and biochemistry of wood decay. PMID:24958869

Transcriptome of an Armillaria root disease pathogen reveals candidate genes involved in host substrate utilization at the host­-pathogen interface

Treesearch

A. L. Ross-Davis; J. E. Stewart; J. W. Hanna; M.-S. Kim; B. J. Knaus; R. Cronn; H. Rai; B. A. Richardson; G. I. McDonald; N. B. Klopfenstein

2013-01-01

Armillaria species display diverse ecological roles ranging from beneficial saprobe to virulent pathogen. Armillaria solidipes (formerly A. ostoyae), a causal agent of Armillaria root disease, is a virulent primary pathogen with a broad host range of woody plants across the Northern Hemisphere. This white-rot pathogen grows between trees as rhizomorphs and attacks...

QTLs for Resistance to Major Rice Diseases Exacerbated by Global Warming: Brown Spot, Bacterial Seedling Rot, and Bacterial Grain Rot.

PubMed

Mizobuchi, Ritsuko; Fukuoka, Shuichi; Tsushima, Seiya; Yano, Masahiro; Sato, Hiroyuki

2016-12-01

In rice (Oryza sativa L.), damage from diseases such as brown spot, caused by Bipolaris oryzae, and bacterial seedling rot and bacterial grain rot, caused by Burkholderia glumae, has increased under global warming because the optimal temperature ranges for growth of these pathogens are relatively high (around 30 °C). Therefore, the need for cultivars carrying genes for resistance to these diseases is increasing to ensure sustainable rice production. In contrast to the situation for other important rice diseases such as blast and bacterial blight, no genes for complete resistance to brown spot, bacterial seedling rot or bacterial grain rot have yet been discovered. Thus, rice breeders have to use partial resistance, which is largely influenced by environmental conditions. Recent progress in molecular genetics and improvement of evaluation methods for disease resistance have facilitated detection of quantitative trait loci (QTLs) associated with resistance. In this review, we summarize the results of worldwide screening for cultivars with resistance to brown spot, bacterial seedling rot and bacterial grain rot and we discuss the identification of QTLs conferring resistance to these diseases in order to provide useful information for rice breeding programs.

Molecular Characterization of Global Regulatory RNA Species That Control Pathogenicity Factors in Erwinia amylovora and Erwinia herbicola pv. gypsophilae†‡

PubMed Central

Ma, Weilei; Cui, Yaya; Liu, Yang; Dumenyo, C. Korsi; Mukherjee, Asita; Chatterjee, Arun K.

2001-01-01

rsmBEcc specifies a nontranslatable RNA regulator that controls exoprotein production and pathogenicity in soft rot-causing Erwinia carotovora subsp. carotovora. This effect of rsmBEcc RNA is mediated mostly by neutralizing the function of RsmAEcc, an RNA-binding protein of E. carotovora subsp. carotovora, which acts as a global negative regulator. To determine the occurrence of functional homologs of rsmBEcc in non-soft-rot-causing Erwinia species, we cloned the rsmB genes of E. amylovora (rsmBEa) and E. herbicola pv. gypsophilae (rsmBEhg). We show that rsmBEa in E. amylovora positively regulates extracellular polysaccharide (EPS) production, motility, and pathogenicity. In E. herbicola pv. gypsophilae, rsmBEhg elevates the levels of transcripts of a cytokinin (etz) gene and stimulates the production of EPS and yellow pigment as well as motility. RsmAEa and RsmAEhg have more than 93% identity to RsmAEcc and, like the latter, function as negative regulators by affecting the transcript stability of the target gene. The rsmB genes reverse the negative effects of RsmAEa, RsmAEhg, and RsmAEcc, but the extent of reversal is highest with homologous combinations of rsm genes. These observations and findings that rsmBEa and rsmBEhg RNA bind RsmAEcc indicate that the rsmB effect is channeled via RsmA. Additional support for this conclusion comes from the observation that the rsmB genes are much more effective as positive regulators in a RsmA+ strain of E. carotovora subsp. carotovora than in its RsmA− derivative. E. herbicola pv. gypsophilae produces a 290-base rsmB transcript that is not subject to processing. By contrast, E. amylovora produces 430- and 300-base rsmB transcripts, the latter presumably derived by processing of the primary transcript as previously noted with the transcripts of rsmBEcc. Southern blot hybridizations revealed the presence of rsmB homologs in E. carotovora, E. chrysanthemi, E. amylovora, E. herbicola, E. stewartii and E. rhapontici, as well as in other enterobacteria such as Escherichia coli, Salmonella enterica serovar Typhimurium, Serratia marcescens, Shigella flexneri, Enterobacter aerogenes, Klebsiella pneumoniae, Yersinia enterocolitica, and Y. pseudotuberculosis. A comparison of rsmB sequences from several of these enterobacterial species revealed a highly conserved 34-mer region which is predicted to play a role in positive regulation by rsmB RNA. PMID:11222584

Fighting phytophthora in blueberries

USDA-ARS?s Scientific Manuscript database

Phytophthora cinnamomi Rands is a ubiquitous soilborne pathogen associated with root rot in many woody perennial plant species, including highbush blueberry (Vaccinium sp.). To identify genotypes with resistance to the pathogen, cultivars and advanced selections of highbush blueberry were grown in a...

Association of Enterobacter cloacae and other bacteria with onion bulb rot in the Columbia Basin of Washington and Oregon, USA

USDA-ARS?s Scientific Manuscript database

Approximately 1.6 million metric tons of onion bulbs are produced annually in the Pacific Northwest USA. Bulb decay can be a major problem and is caused by a variety of plant pathogens. Onion bulbs exhibiting symptoms of bacterial rot were sampled to determine the causal agents. Enterobacter cloacae...

Long-term effects of stump removal to control root rot on forest soil bulk density, soil carbon and nitrogen content.

Treesearch

D. Zabowski; D. Chambrear; N. Rotramel; W.G. Thies

2008-01-01

Phellinus weirii (Mum.) Gilb is a native pathogen in the forests of the Northwestern United States causing laminated root rot and mortality in Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) and other susceptible conifer species. This facultative saprophyte is a natural part of the ecosystem, present in most Douglas-fir...

Potassium fertilizer applied immediately after planting had no impact on Douglas-fir seedling mortality caused by laminated root rot on a forested site in Washington State.

Treesearch

Walter G. Thies; Rick G. Kelsey; Douglas J. Westlind; Jeff Madsen

2006-01-01

Phellinus weirii causes laminated root rot (LRR), a major disease affecting growth and survival of Pseudotsuga menziesii (Douglas-fir) and other commercially important conifer species throughout the Pacific Northwest. Increasing tree vigor and resistance to pathogens through application of K fertilizer is a suggested disease...

Multiplex assay for the quantitative assessment of Rhizoctonia solani AG2-2, AG4 and Rhizoctonia zeae from the soil

USDA-ARS?s Scientific Manuscript database

Rhizoctonia solani causes damping off and root and crown rot in sugar beets resulting in substantial losses in the field and during storage. Root rot is a difficult fungal disease to diagnose and manage, as the pathogen is usually not detected until after damage has occurred. The objective of this s...

Extensive sampling of basidiomycete genomes demonstrates inadequacy of the white rot/ brown rot paradigm for wood decay fungi

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

Riley, Robert; Salamov, Asaf; Brown, Daren W.

Basidiomycota (basidiomycetes) make up 32percent of the described fungi and include most wood decaying species, as well as pathogens and mutualistic symbionts. Wood-decaying basidiomycetes have typically been classified as either white rot or brown rot, based on the ability (in white rot only) to degrade lignin along with cellulose and hemicellulose. Prior genomic comparisons suggested that the two decay modes can be distinguished based on the presence or absence of ligninolytic class II peroxidases (PODs), as well as the abundance of enzymes acting directly on crystalline cellulose (reduced in brown rot). To assess the generality of the white rot/brown rotmore » classification paradigm we compared the genomes of 33 basidiomycetes, including four newly sequenced wood decayers, and performed phylogenetically-informed Principal Components Analysis (PCA) of a broad range of gene families encoding plant biomass-degrading enzymes. The newly sequenced Botryobasidium botryosum and Jaapia argillacea genomes lack PODs, but possess diverse enzymes acting on crystalline cellulose, and they group close to the model white rot species Phanerochaete chrysosporium in the PCA. Furthermore, laboratory assays showed that both B. botryosum and J. argillacea can degrade all polymeric components of woody plant cell walls, a characteristic of white rot. We also found expansions in reducing polyketide synthase genes specific to the brown rot fungi. Our results suggest a continuum rather than a dichotomy between the white rot and brown rot modes of wood decay. A more nuanced categorization of rot types is needed, based on an improved understanding of the genomics and biochemistry of wood decay.« less

Pathogenicity of Nectriaceous Fungi on Avocado in Australia.

PubMed

Parkinson, Louisamarie E; Shivas, Roger G; Dann, Elizabeth K

2017-12-01

Black root rot is a severe disease of young avocado trees in Australia causing black necrotic roots, tree stunting, and leaf drop prior to tree death. Nectriaceous fungi (Nectriaceae, Hypocreales), are commonly isolated from symptomatic roots. This research tested the pathogenicity of 19 isolates from Calonectria, Cylindrocladiella, Dactylonectria, Gliocladiopsis, and Ilyonectria, spp. collected from young avocado trees and other hosts. Glasshouse pathogenicity tests with 'Reed' avocado (Persea americana) seedlings confirmed that Calonectria ilicicola is a severe pathogen of avocado, causing stunting, wilting, and seedling death within 5 weeks of inoculation. Isolates of C. ilicicola from peanut, papaya, and custard apple were also shown to be aggressive pathogens of avocado, demonstrating a broad host range. An isolate of a Calonectria sp. from blueberry and avocado isolates of Dactylonectria macrodidyma, D. novozelandica, D. pauciseptata, and D. anthuriicola caused significant root rot but not stunting within 5 to 9 weeks of inoculation. An isolate of an Ilyonectria sp. from grapevine closely related to Ilyonectria liriodendri, and avocado isolates of Cylindrocladiella pseudoinfestans, Gliocladiopsis peggii, and an Ilyonectria sp. were not pathogenic to avocado.

First report of a cross-kingdom pathogenic bacterium, Achromobacter xylosoxidans isolated from stipe-rot Coprinus comatus.

PubMed

Ye, Luona; Guo, Mengpei; Ren, Pengfei; Wang, Gangzheng; Bian, Yinbing; Xiao, Yang; Zhou, Yan

2018-03-01

Coprinus comatus is an edible mushroom widely cultivated in China as a delicious food. Various diseases have occurred on C. comatus with the cultivated area increasing. In this study, the pathogenic bacterium JTG-B1, identified as Achromobacter xylosoxidans by 16S rDNA and nrdA gene sequencing, was isolated from edible mushroom Coprinus comatus with serious rot disease on its stipe. A. xylosoxidans has been confirmed as an important opportunistic human pathogenic bacterium and has been isolated from respiratory samples from cystic fibrosis. It is widely distributed in the environment. Here, we first report that fungi can also serve as a host for A. xylosoxidans. We confirmed that it can cross-kingdom infect between animals (mice) and fungi (C. comatus). The results of pathogenicity tests, physiological, biochemical and genotyping analysis of A. xylosoxidans from different hosts suggested that different strain of A. xylosoxidans may have pathogenicity differentiation. A. xylosoxidans not only is pathogenic to C. comatus but also may threaten human health. Copyright © 2017 Elsevier GmbH. All rights reserved.

Antimicrobial activity of pyrrocidines from Acremonium zeae against endophytes and pathogens of maize.

PubMed

Wicklow, Donald T; Poling, Stephen M

2009-01-01

Acremonium zeae produces pyrrocidines A and B, which are polyketide-amino acid-derived antibiotics, and is recognized as a seedborne protective endophyte of maize which augments host defenses against microbial pathogens causing seedling blights and stalk rots. Pyrrocidine A displayed significant in vitro activity against Aspergillus flavus and Fusarium verticillioides in assays performed using conidia as inoculum, with pyrrocidine A being more active than B. In equivalent assays performed with conidia or hyphal cells as inoculum, pyrrocidine A revealed potent activity against major stalk and ear rot pathogens of maize, including F. graminearum, Nigrospora oryzae, Stenocarpella (Diplodia) maydis, and Rhizoctonia zeae. Pyrrocidine A displayed significant activity against seed-rotting saprophytes A. flavus and Eupenicillium ochrosalmoneum, as well as seed-infecting colonists of the phylloplane Alternaria alternata, Cladosporium cladosporioides, and Curvularia lunata, which produces a damaging leaf spot disease. Protective endophytes, including mycoparasites which grow asymptomatically within healthy maize tissues, show little sensitivity to pyrrocidines. Pyrrocidine A also exhibited potent activity against Clavibacter michiganense subsp. nebraskense, causal agent of Goss's bacterial wilt of maize, and Bacillus mojaviense and Pseudomonas fluorescens, maize endophytes applied as biocontrol agents, but were ineffective against the wilt-producing bacterium Pantoea stewartii.

7 CFR 51.1901 - U.S. Grade A.

Code of Federal Regulations, 2011 CFR

2011-01-01

... are not overripe or soft which are well developed, at least fairly well formed, fairly smooth, free..., sunburn, puffiness, catfaces, growth cracks, scars, dry rot, other diseases, insects, hail, or mechanical...

Comparative Genome Analysis of Basidiomycete Fungi

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

Riley, Robert; Salamov, Asaf; Morin, Emmanuelle

Fungi of the phylum Basidiomycota (basidiomycetes), make up some 37percent of the described fungi, and are important in forestry, agriculture, medicine, and bioenergy. This diverse phylum includes the mushrooms, wood rots, symbionts, and plant and animal pathogens. To better understand the diversity of phenotypes in basidiomycetes, we performed a comparative analysis of 35 basidiomycete fungi spanning the diversity of the phylum. Phylogenetic patterns of lignocellulose degrading genes suggest a continuum rather than a sharp dichotomy between the white rot and brown rot modes of wood decay. Patterns of secondary metabolic enzymes give additional insight into the broad array of phenotypesmore » found in the basidiomycetes. We suggest that the profile of an organism in lignocellulose-targeting genes can be used to predict its nutritional mode, and predict Dacryopinax sp. as a brown rot; Botryobasidium botryosum and Jaapia argillacea as white rots.« less

Organic neem compounds inhibit soft-rot fungal growth and improve the strength of anthracite bricks bound with collagen and lignin for use in iron foundry cupolas.

PubMed

Kelsey, D J; Nieto-Delgado, C; Cannon, F S; Brennan, R A

2015-07-01

To examine organic neem compounds for their effective growth inhibition of saprotrophic soft-rot fungi on anthracite bricks bound with collagen and lignin for use in iron foundry cupolas as an alternative fuel source. Azadirachtin, crude neem oil (NO), and clarified neem oil extract (CNO) were combined with copper to inhibit the growth of the soft-rot fungus, Chaetomium globosum. A synergistic interaction was observed between CNO and a low dose of copper on nutrient media (two-factor anova with triplicate replication: P < 0·05). Interaction was confirmed on lab-scale collagen-lignin-anthracite briquettes by measuring their unconfined compressive (UC) strength. The effective collagen strength of the briquettes was enhanced by applying CNO to their surface prior to inoculation: the room temperature UC strength of the briquettes was 28 ± 4·6% greater when CNO (0·4 mg cm(-2) ) was surface-applied, and was 43 ± 3·0% greater when CNO plus copper (0·14 μg cm(-2) ) were surface-applied. Surface application of CNO and copper synergistically prevents fungal growth on bindered anthracite briquettes and increases their room temperature strength. This novel organic fungicidal treatment may increase the storage and performance of anthracite bricks in iron foundries, thereby saving 15-20% of the energy used in conventional coke production. © 2015 The Society for Applied Microbiology.

Expression and characterization of aiiA gene from Bacillus subtilis BS-1.

PubMed

Pan, Jieru; Huang, Tianpei; Yao, Fan; Huang, Zhipeng; Powell, Charles A; Qiu, Sixin; Guan, Xiong

2008-01-01

AHL-lactonase (AiiA), a metallo-beta-lactamase produced by Bacillus thuringiensis, Bacillus cereus and Bacillus anthracis, specifically hydrolyzes N-acyl-homoserine lactones (AHLs) secreted by Gram-negative bacteria and thereby attenuates the symptoms caused by plant pathogens. In this study, an aiiA gene was cloned from Bacillus subtilis BS-1 by PCR with a pair of degenerate primers. The deduced 250 amino acid sequence contained two small conserved regions, 103SHLHFDH109 and 166TPGHTPGH173, which are characteristic of the metallo-beta-lactamase family. Homology comparison revealed that the deduced amino acid sequence had a high degree of similarity with those of the known AiiA proteins in the B. cereus group. Additionally, the aiiA gene was expressed in Escherichia coli BL21 (DE3) pLysS and the expressed AiiA protein could attenuate the soft rot symptoms caused by Erwinia carotovora var. carotovora.

Draft Genome Sequence of the Phytopathogenic Fungus Ganoderma boninense, the Causal Agent of Basal Stem Rot Disease on Oil Palm

PubMed Central

Tanjung, Zulfikar Achmad; Aditama, Redi; Buana, Rika Fithri Nurani; Pratomo, Antonius Dony Madu; Tryono, Reno; Liwang, Tony

2018-01-01

ABSTRACT Ganoderma boninense is the dominant fungal pathogen of basal stem rot (BSR) disease on Elaeis guineensis. We sequenced the nuclear genome of mycelia using both Illumina and Pacific Biosciences platforms for assembly of scaffolds. The draft genome comprised 79.24 Mb, 495 scaffolds, and 26,226 predicted coding sequences. PMID:29700132

Genome and secretome analysis of the hemibiotrophic fungal pathogen, Moniliophthora roreri, which causes frosty pod rot disease of cacao: mechanisms of the biotrophic and necrotrophic phases

USDA-ARS?s Scientific Manuscript database

Background: Moniliophthora roreri is the causal agent of Frosty pod rot (FPR) disease of Theobroma cacao, the source of chocolate and is one of the most destructive diseases of cacao in the Americas. This Basidiomycete only infects cacao pods and has an extended biotrophic phase lasting up to sixty ...

Phytophthora megakarya and P. palmivora, closely related causal agents of cacao black pod rot, underwent increases in genome sizes and gene numbers by different mechanisms

USDA-ARS?s Scientific Manuscript database

Phytophthora megakarya (Pmeg) and P. palmivora (Ppal) are closely related species causing black pod rot of cacao. While Ppal is a cosmopolitan plant pathogen, cacao is the only known host of importance for Pmeg. Pmeg is more virulent on cacao than Ppal. Therefore, we have sequenced both the Pmeg and...

Development of biocontrol agents from food microbial isolates for controlling post-harvest peach brown rot caused by Monilinia fructicola.

PubMed

Zhou, Ting; Schneider, Karin E; Li, Xiu-Zhen

2008-08-15

An unconventional strategy of screening food microbes for biocontrol activity was used to develop biocontrol agents for controlling post-harvest peach brown rot caused by Monilinia fructicola. Forty-four microbial isolates were first screened for their biocontrol activity on apple fruit. Compared with the pathogen-only check, seven of the 44 isolates reduced brown rot incidence by >50%, including four bacteria: Bacillus sp. C06, Lactobacillus sp. C03-b and Bacillus sp. T03-c, Lactobacillus sp. P02 and three yeasts: Saccharomyces delbrueckii A50, S. cerevisiae YE-5 and S. cerevisiae A41. Eight microbial isolates were selected for testing on peaches by wound co-inoculation with mixtures of individual microbial cultures and conidial suspension of M. fructicola. Only two of them showed significant biocontrol activity after five days of incubation at 22 degrees C. Bacillus sp. C06 suppressed brown rot incidence by 92% and reduced lesion diameter by 88% compared to the pathogen-only check. Bacillus sp.T03-c reduced incidence and lesion diameter by 40% and 62%, respectively. The two isolates were compared with Pseudomonas syringae MA-4, a biocontrol agent for post-harvest peach diseases, by immersing peaches in an aliquot containing individual microbial isolates and the pathogen conidia. Treatments with isolates MA-4, C06 and T03-c significantly controlled brown rot by 91, 100, and 100% respectively. However, only isolates MA-4 and C06 significantly reduced brown rot by 80% and 15%, respectively when bacterial cells alone were applied. On naturally infected peaches, both the bacterial culture and its cell-free filtrate of the isolate C06 significantly controlled peach decay resulting in 77 and 90% reduction, respectively, whereas the treatment using only the bacterial cells generally had no effect. Isolate C06 is a single colony isolate obtained from a mesophilic cheese starter, and has been identified belonging to Bacillus amyloliquefaciens. The results have clearly demonstrated that isolate C06 has a great potential for being developed into a biocontrol agent.

Structure-based functional characterization of repressor of toxin (Rot), a central regulator of staphylococcus aureus virulence

DOE PAGES

Killikelly, April; Jakoncic, Jean; Benson, Meredith A.; ...

2014-10-20

Staphylococcus aureus is responsible for a large number of diverse infections worldwide. In order to support its pathogenic lifestyle, S. aureus has to regulate the expression of virulence factors in a coordinated fashion. One of the central regulators of the S. aureus virulence regulatory networks is the transcription factor repressor of toxin (Rot). Rot plays a key role in regulating S. aureus virulence through activation or repression of promoters that control expression of a large number of critical virulence factors. However, the mechanism by which Rot mediates gene regulation has remained elusive. Here, we have determined the crystal structure ofmore » Rot and used this information to probe the contribution made by specific residues to Rot function. Rot was found to form a dimer, with each monomer harboring a winged helix-turn-helix (WHTH) DNA-binding motif. Despite an overall acidic pI, the asymmetric electrostatic charge profile suggests that Rot can orient the WHTH domain to bind DNA. Structure-based site-directed mutagenesis studies demonstrated that R 91, at the tip of the wing, plays an important role in DNA binding, likely through interaction with the minor groove. We also found that Y 66, predicted to bind within the major groove, contributes to Rot interaction with target promoters. Evaluation of Rot binding to different activated and repressed promoters revealed that certain mutations on Rot exhibit promoter-specific effects, suggesting for the first time that Rot differentially interacts with target promoters. As a result, this work provides insight into a precise mechanism by which Rot controls virulence factor regulation in S. aureus.« less

Structure-based functional characterization of repressor of toxin (Rot), a central regulator of staphylococcus aureus virulence

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

Killikelly, April; Jakoncic, Jean; Benson, Meredith A.

Staphylococcus aureus is responsible for a large number of diverse infections worldwide. In order to support its pathogenic lifestyle, S. aureus has to regulate the expression of virulence factors in a coordinated fashion. One of the central regulators of the S. aureus virulence regulatory networks is the transcription factor repressor of toxin (Rot). Rot plays a key role in regulating S. aureus virulence through activation or repression of promoters that control expression of a large number of critical virulence factors. However, the mechanism by which Rot mediates gene regulation has remained elusive. Here, we have determined the crystal structure ofmore » Rot and used this information to probe the contribution made by specific residues to Rot function. Rot was found to form a dimer, with each monomer harboring a winged helix-turn-helix (WHTH) DNA-binding motif. Despite an overall acidic pI, the asymmetric electrostatic charge profile suggests that Rot can orient the WHTH domain to bind DNA. Structure-based site-directed mutagenesis studies demonstrated that R 91, at the tip of the wing, plays an important role in DNA binding, likely through interaction with the minor groove. We also found that Y 66, predicted to bind within the major groove, contributes to Rot interaction with target promoters. Evaluation of Rot binding to different activated and repressed promoters revealed that certain mutations on Rot exhibit promoter-specific effects, suggesting for the first time that Rot differentially interacts with target promoters. As a result, this work provides insight into a precise mechanism by which Rot controls virulence factor regulation in S. aureus.« less

Growth Promoting Rhizospheric and Endophytic Bacteria from Curcuma longa L. as Biocontrol Agents against Rhizome Rot and Leaf Blight Diseases.

PubMed

Vinayarani, G; Prakash, H S

2018-06-01

Plant growth promoting rhizobacteria and endophytic bacteria were isolated from different varieties of turmeric ( Curcuma longa L.) from South India. Totally 50 strains representing, 30 PGPR and 20 endophytic bacteria were identified based on biochemical assays and 16S rDNA sequence analysis. The isolates were screened for antagonistic activity against Pythium aphanidermatum (Edson) Fitzp., and Rhizoctonia solani Kuhn., causing rhizome rot and leaf blight diseases in turmeric, by dual culture and liquid culture assays. Results revealed that only five isolates of PGPR and four endophytic bacteria showed more than 70% suppression of test pathogens in both assays. The SEM studies of interaction zone showed significant ultrastructural changes of the hyphae like shriveling, breakage and desication of the pathogens by PGPR B. cereus (RBac-DOB-S24) and endophyte P. aeruginosa (BacDOB-E19). Selected isolates showed multiple Plant growth promoting traits. The rhizome bacterization followed by soil application of B. cereus (RBacDOB-S24) showed lowest Percent Disease Incidence (PDI) of rhizome rot and leaf blight, 16.4% and 15.5% respectively. Similarly, P. aeruginosa (BacDOB-E19) recorded PDI of rhizome rot (17.5%) and leaf blight (17.7%). The treatment of these promising isolates exhibited significant increase in plant height and fresh rhizome yield/plant in comparison with untreated control under greenhouse condition. Thereby, these isolates can be exploited as a potential biocontrol agent for suppressing rhizome rot and leaf blight diseases in turmeric.

Comparative genome analysis of rice-pathogenic Burkholderia provides insight into capacity to adapt to different environments and hosts.

PubMed

Seo, Young-Su; Lim, Jae Yun; Park, Jungwook; Kim, Sunyoung; Lee, Hyun-Hee; Cheong, Hoon; Kim, Sang-Mok; Moon, Jae Sun; Hwang, Ingyu

2015-05-06

In addition to human and animal diseases, bacteria of the genus Burkholderia can cause plant diseases. The representative species of rice-pathogenic Burkholderia are Burkholderia glumae, B. gladioli, and B. plantarii, which primarily cause grain rot, sheath rot, and seedling blight, respectively, resulting in severe reductions in rice production. Though Burkholderia rice pathogens cause problems in rice-growing countries, comprehensive studies of these rice-pathogenic species aiming to control Burkholderia-mediated diseases are only in the early stages. We first sequenced the complete genome of B. plantarii ATCC 43733T. Second, we conducted comparative analysis of the newly sequenced B. plantarii ATCC 43733T genome with eleven complete or draft genomes of B. glumae and B. gladioli strains. Furthermore, we compared the genome of three rice Burkholderia pathogens with those of other Burkholderia species such as those found in environmental habitats and those known as animal/human pathogens. These B. glumae, B. gladioli, and B. plantarii strains have unique genes involved in toxoflavin or tropolone toxin production and the clustered regularly interspaced short palindromic repeats (CRISPR)-mediated bacterial immune system. Although the genome of B. plantarii ATCC 43733T has many common features with those of B. glumae and B. gladioli, this B. plantarii strain has several unique features, including quorum sensing and CRISPR/CRISPR-associated protein (Cas) systems. The complete genome sequence of B. plantarii ATCC 43733T and publicly available genomes of B. glumae BGR1 and B. gladioli BSR3 enabled comprehensive comparative genome analyses among three rice-pathogenic Burkholderia species responsible for tissue rotting and seedling blight. Our results suggest that B. glumae has evolved rapidly, or has undergone rapid genome rearrangements or deletions, in response to the hosts. It also, clarifies the unique features of rice pathogenic Burkholderia species relative to other animal and human Burkholderia species.

Temporal Occurrence and Niche Preferences of Phytophthora spp. Causing Brown Rot of Citrus in the Central Valley of California.

PubMed

Hao, Wei; Miles, Timothy D; Martin, Frank N; Browne, Gregory T; Förster, Helga; Adaskaveg, James E

2018-03-01

Brown rot of citrus fruit is caused by several species of Phytophthora and is currently of serious concern for the California citrus industry. Two species, Phytophthora syringae and P. hibernalis, are quarantine pathogens in China, a major export market for California citrus. To maintain trade and estimate the risk of exporting a quarantine pathogen, the distribution and frequency of Phytophthora spp. causing brown rot of orange in major growing areas of California was investigated. Symptomatic fruit were collected from navel (winter to late spring) and Valencia (late spring to summer) orange orchards from 2013 to 2015. Species identification of isolates was based on morphological characteristics, random amplified polymorphic DNA banding patterns, and sequencing of the internal transcribed spacer and the partial cox2/spacer/cox1 regions from axenic cultures, or directly on DNA from fruit tissue using a multiplex TaqMan quantitative polymerase chain reaction assay. In winter samplings, the incidence of P. syringae based on the number of fruit with Phytophthora spp. detection ranged from 73.6 to 96.1% for the two counties surveyed. The remaining isolates were identified as P. citrophthora. In late spring or summer, only P. citrophthora was recovered. P. hibernalis and P. nicotianae were not detected in any fruit with brown rot symptoms. These results indicate that P. syringae is currently an important brown rot pathogen of citrus fruit in California during the cooler seasons of the year. In winter 2016 and 2017, P. syringae was recovered by pear baiting at a high incidence from leaf litter and from a small number of rhizosphere soil or root samples but not from living leaves on the tree. In contrast, P. citrophthora was rarely found in leaf litter but was commonly detected in the rhizosphere. Thus, leaf litter is a major inoculum source for P. syringae and this species occupies a distinct ecological niche.

Draft Genome Sequence of the Phytopathogenic Fungus Ganoderma boninense, the Causal Agent of Basal Stem Rot Disease on Oil Palm.

PubMed

Utomo, Condro; Tanjung, Zulfikar Achmad; Aditama, Redi; Buana, Rika Fithri Nurani; Pratomo, Antonius Dony Madu; Tryono, Reno; Liwang, Tony

2018-04-26

Ganoderma boninense is the dominant fungal pathogen of basal stem rot (BSR) disease on Elaeis guineensis We sequenced the nuclear genome of mycelia using both Illumina and Pacific Biosciences platforms for assembly of scaffolds. The draft genome comprised 79.24 Mb, 495 scaffolds, and 26,226 predicted coding sequences. Copyright © 2018 Utomo et al.

Molecular Characterization of Resistant Accessions of Cocoa (Theobroma cocoa L.) to Phytophthora Pod Rot Selected on-Farm in Côte-d’Ivoire.

USDA-ARS?s Scientific Manuscript database

Cocoa is (Theobroma cacao L.) is a significant agricultural commodity in Côted’Ivoire which ranks 1st in the world cocoa export. Phytophthora pod rot (Ppr)also call Black pod is the most widespread disease of cocoa. Lost due to this disease depends on the species of the pathogen and vary globally fr...

Development and application of qPCR and RPA genus and species-specific detection of Phytophthora sojae and Phytophthora sansomeana root rot pathogens of soybean

USDA-ARS?s Scientific Manuscript database

Phytophthora root rot of soybean, caused by Phytophthora sojae is one of the most important diseases in the Midwest US, causing losses of up to 44 million bushels per year. Disease may also be caused by P. sansomeana, however the prevalence and damage caused by this species is not well known, partl...

Efficacy of Chaetomium Species as Biological Control Agents against Phytophthora nicotianae Root Rot in Citrus

PubMed Central

Wattanachai, Pongnak; Kasem, Soytong; Poeaim, Supattra

2015-01-01

Thailand is one of the largest citrus producers in Southeast Asia. Pathogenic infection by Phytophthora, however, has become one of major impediments to production. This study identified a pathogenic oomycete isolated from rotted roots of pomelo (Citrus maxima) in Thailand as Phytophthora nicotianae by the internal transcribed spacer ribosomal DNA sequence analysis. Then, we examined the in vitro and in vivo effects of Chaetomium globosum, Chaetomium lucknowense, Chaetomium cupreum and their crude extracts as biological control agents in controlling this P. nicotianae strain. Represent as antagonists in biculture test, the tested Chaetomium species inhibited mycelial growth by 50~56% and parasitized the hyphae, resulting in degradation of P. nicotianae mycelia after 30 days. The crude extracts of these Chaetomium species exhibited antifungal activities against mycelial growth of P. nicotianae, with effective doses of 2.6~101.4 µg/mL. Under greenhouse conditions, application of spores and methanol extracts of these Chaetomium species to pomelo seedlings inoculated with P. nicotianae reduced root rot by 66~71% and increased plant weight by 72~85% compared to that in the control. The method of application of antagonistic spores to control the disease was simple and economical, and it may thus be applicable for large-scale, highly effective biological control of this pathogen. PMID:26539045

Detoxification of fusaric acid by the soil microbe Mucor rouxii

USDA-ARS?s Scientific Manuscript database

An unusually aggressive biotype of the root rotting pathogen of cotton, Fusarium oxysporum f. sp. vasinfectum (Fov), has been identified in the Western Hemisphere in some cotton fields in California. This pathogen produces copious quantities of the plant toxin fusaric acid (5-butyl-2-pyridinecarbox...

Phylogenetic, Morphological, and Pathogenic Characterization of Alternaria Species Associated with Fruit Rot of Blueberry in California.

PubMed

Zhu, X Q; Xiao, C L

2015-12-01

Fruit rot caused by Alternaria spp. is one of the most important factors affecting the postharvest quality and shelf life of blueberry fruit. The aims of this study were to characterize Alternaria isolates using morphological and molecular approaches and test their pathogenicity to blueberry fruit. Alternaria spp. isolates were collected from decayed blueberry fruit in the Central Valley of California during 2012 and 2013. In total, 283 isolates were obtained and five species of Alternaria, including Alternaria alternata, A. tenuissima, A. arborescens, A. infectoria, and A. rosae, were identified based on DNA sequences of the plasma membrane ATPase, Alt a1 and Calmodulin gene regions in combination with morphological characters of the culture and sporulation. Of the 283 isolates, 61.5% were identified as A. alternata, 32.9% were A. arborescens, 5.0% were A. tenuissima, and only one isolate of A. infectoria and one isolate of A. rosae were found. These fungi were able to grow at temperatures from 0 to 35°C, and mycelial growth was arrested at 40°C. Optimal radial growth occurred between 20 to 30°C. Pathogenicity tests showed that all five Alternaria spp. were pathogenic on blueberry fruit at 0, 4, and 20°C, with A. alternata, A. arborescens, and A. tenuissima being the most virulent species, followed by A. infectoria and A. rosae. Previously A. tenuissima has been reported to be the primary cause of Alternaria fruit rot of blueberry worldwide. Our results indicated that the species composition of Alternaria responsible for Alternaria fruit rot in blueberry can be dependent on geographical region. A. alternata, A. arborescens, A. infectoria, and A. rosae are reported for the first time on blueberry in California. This is also the first report of A. infectoria and A. rosae infecting blueberry fruit.

Xanthomonas campestris pv. campestris (cause of black rot of crucifers) in the genomic era is still a worldwide threat to brassica crops.

PubMed

Vicente, Joana G; Holub, Eric B

2013-01-01

Xanthomonas campestris pv. campestris (Xcc) (Pammel) Dowson is a Gram-negative bacterium that causes black rot, the most important disease of vegetable brassica crops worldwide. Intensive molecular investigation of Xcc is gaining momentum and several whole genome sequences are available. Bacteria; Phylum Proteobacteria; Class Gammaproteobacteria; Order Xanthomonadales; Family Xanthomonadacea; Genus Xanthomonas; Species X. campestris. Xcc can cause disease in a large number of species of Brassicaceae (ex-Cruciferae), including economically important vegetable Brassica crops and a number of other cruciferous crops, ornamentals and weeds, including the model plant Arabidopsis thaliana. Black rot is a systemic vascular disease. Typical disease symptoms include V-shaped yellow lesions starting from the leaf margins and blackening of the veins. Collections of Xcc isolates have been differentiated into physiological races based on the response of several brassica species lines. Black rot is a seed-borne disease. The disease is favoured by warm, humid conditions and can spread rapidly from rain dispersal and irrigation water. The control of black rot is difficult and relies on the use of pathogen-free planting material and the elimination of other potential inoculum sources (infected crop debris and cruciferous weeds). Major gene resistance is very rare in B. oleracea (brassica C genome). Resistance is more readily available in other species, including potentially useful sources of broad-spectrum resistance in B. rapa and B. carinata (A and BC genomes, respectively) and in the wild relative A. thaliana. The reference genomes of three isolates have been released. The genome consists of a single chromosome of approximately 5 100 000 bp, with a GC content of approximately 65% and an average predicted number of coding DNA sequences (CDS) of 4308. Three different secretion systems have been identified and studied in Xcc. The gene clusters xps and xcs encode a type II secretion system and xps genes have been linked to pathogenicity. The role of the type IV secretion system in pathogenicity is still uncertain. The hrp gene cluster encodes a type III secretion system that is associated with pathogenicity. An inventory of candidate effector genes has been assembled based on homology with known effectors. A range of other genes have been associated with virulence and pathogenicity, including the rpf, gum and wxc genes involved in the regulation of the synthesis of extracellular degrading enzymes, xanthan gum and lipopolysaccharides. http://www.xanthomonas.org/ © 2012 THE AUTHORS. MOLECULAR PLANT PATHOLOGY © 2012 BSPP AND BLACKWELL PUBLISHING LTD.

Fusarium crown rot caused by Fusarium pseudograminearum in cereal crops: recent progress and future prospects.

PubMed

Kazan, Kemal; Gardiner, Donald M

2017-11-04

Diseases caused by Fusarium pathogens inflict major yield and quality losses on many economically important plant species worldwide, including cereals. Fusarium crown rot (FCR), caused by Fusarium pseudograminearum, is a cereal disease that occurs in many arid and semi-arid cropping regions of the world. In recent years, this disease has become more prevalent, in part as a result of the adoption of moisture-preserving cultural practices, such as minimum tillage and stubble retention. In this pathogen profile, we present a brief overview of recent research efforts that have not only advanced our understanding of the interactions between F. pseudograminearum and cereal hosts, but have also provided new disease management options. For instance, significant progress has been made in the genetic characterization of pathogen populations, the development of new tools for disease prediction, and the identification and pyramiding of loci that confer quantitative resistance to FCR in wheat and barley. In addition, transcriptome analyses have revealed new insights into the processes involved in host defence. Significant progress has also been made in understanding the mechanistic details of the F. pseudograminearum infection process. The sequencing and comparative analyses of the F. pseudograminearum genome have revealed novel virulence factors, possibly acquired through horizontal gene transfer. In addition, a conserved pathogen gene cluster involved in the degradation of wheat defence compounds has been identified, and a role for the trichothecene toxin deoxynivalenol (DON) in pathogen virulence has been reported. Overall, a better understanding of cereal host-F. pseudograminearum interactions will lead to the development of new control options for this increasingly important disease problem. Taxonomy: Fusarium pseudograminearum O'Donnell & Aoki; Kingdom Fungi; Phylum Ascomycota; Subphylum Pezizomycotina; Class Sordariomycetes; Subclass Hypocreomycetidae; Order Hypocreales; Family Nectriaceae; Genus Fusarium. Disease symptoms: Fusarium crown rot caused by F. pseudograminearum is also known as crown rot, foot rot and root rot. Infected seedlings can die before or after emergence. If infected seedlings survive, typical disease symptoms are browning of the coleoptile, subcrown internode, lower leaf sheaths and adjacent stems and nodal tissues; this browning can become evident within a few weeks after planting or throughout plant development. Infected plants may develop white heads with no or shrivelled grains. Disease symptoms are exacerbated under water limitation. Identification and detection: Fusarium pseudograminearum macroconidia usually contain three to five septa (22-60.5 × 2.5-5.5 μm). On potato dextrose agar (PDA), aerial mycelia appear floccose and reddish white, with red or reddish-brown reverse pigmentation. Diagnostic polymerase chain reaction (PCR) tests based on the amplification of the gene encoding translation elongation factor-1a (TEF-1a) have been developed for molecular identification. Host range: All major winter cereals can be colonized by F. pseudograminearum. However, the main impact of this pathogen is on bread (Triticum aestivum L.) and durum (Triticum turgidum L. spp. durum (Dest.)) wheat and barley (Hordeum vulgare L.). Oats (Avena sativa L.) can be infected, but show little or no disease symptoms. In addition, the pathogen has been isolated from various other grass genera, such as Phalaris, Agropyron and Bromus, which may occur as common weeds. Useful websites: https://nt.ars-grin.gov/fungaldatabases/; http://plantpath.psu.edu/facilities/fusarium-research-center; https://nt.ars-grin.gov/fungaldatabases/; http://www.speciesfungorum.org/Names/Names.asp. © 2017 BSPP AND JOHN WILEY & SONS LTD.

Pathogenicity of some Rhizoctonia solaniz isolates associated with root/collar rots on the cultivars of bean in greenhouse.

PubMed

Bohlooli, A; Okhovvat, S M; Javan-Nikkhah, M

2006-01-01

One hundred and eighteen isolates of Rhizoctonia solani were gathered from infected roots and hypocotyls of bean (Phaseolus vulgaris L.) grown in the fields of Tehran Province, Iran. Two isolates of the collected samples belonged to binucleate and 81 isolates to multinucleate of R. solani. The multinucleate isolates showed different anastomosis groups as AG-4 (subg. AG-4 HGI, AG-4HGII), AG-6 and AG-2. In greenhouse, pathogenicity tests carried out on bean cv. Naz in randomized design with 4 replications and each replication (pots) with 5 seeds of bean. Infection was done with seeds of wheat which were infected to the fungus with pasteurized soil. Results showed that the highest disease severity was caused by AG-4 (Rs21) isolates, whereas AG-4 (Rs74) isolates were weakly pathogenic with 90% and 21% infection, respectively. In this test the major pathogenic isolates belonged to AG-4 and they caused seed rot and damping-off of bean and AG-6 isolates were non-pathogenic. Five isolates of the fungus with major pathogenicity (Rs7, Rs18, Rs21, Rs62 and Rs71) selected and used for the reaction with different cultivars of bean. In this test, the cultivars and lines of bean (Pinto, red, white, green) studied in factorial experiment as randomized block design with 4 replications (pots). Results showed that none of the cultivars was completely resistant, however green bean cv. Sanry and pinto cv. Shad with number 4.8 disease severities had the highest susceptibility to seed rot and damping-off and red bean cv. Goli with 2.58 had the lowest susceptibility to the infection. Reaction of the cultivars and lines to the isolates of R. solani was significantly different at 1% level. Isolates of the fungus, Rs7, Rs21 with 84%, 90% pathogenicity was more virulent than the others.

Identification and characterization of LysM effectors in Penicillium expansum

USDA-ARS?s Scientific Manuscript database

P. expansum is regarded as one of the most important postharvest rots of apple fruit and is also of great concern to fruit processing industries. Elucidating the pathogenicity mechanism of this pathogen is of utmost importance for the development of effective and safe management strategies. Althou...

Characterization of stuA mutants in the mycotoxigenic maize pathogen Fusarium verticillioides

USDA-ARS?s Scientific Manuscript database

Fusarium verticillioides is a major pathogen of maize, causing root, stalk and ear rots and seedling blight. It also produces fumonisin mycotoxins. Ingestion of fumonisin-contaminated corn causes acute toxicity in livestock and is a potential carcinogen to humans. StuA, an APSES protein class transc...

Use of jasmonic acid and salicylic acid to inhibit growth of sugarbeet storage rot pathogens

USDA-ARS?s Scientific Manuscript database

Jasmonic acid (JA) and salicylic acid (SA) are endogenous plant hormones that induce native plant defense responses and provide protection against a wide range of diseases. Previously, JA, applied after harvest, was shown to protect sugarbeet roots against the storage pathogens, Botrytis cinerea, P...

Selection and validation of enzymatic activities as functional markers in wood biotechnology and fungal ecology.

PubMed

Mathieu, Yann; Gelhaye, Eric; Dumarçay, Stéphane; Gérardin, Philippe; Harvengt, Luc; Buée, Marc

2013-02-15

The dead wood and forest soils are sources of diversity and under-explored fungal strains with biotechnological potential, which require to be studied. Numerous enzymatic tests have been proposed to investigate the functional potential of the soil microbial communities or to test the functional abilities of fungal strains. Nevertheless, the diversity of these functional markers and their relevance in environmental studies or biotechnological screening does still have not been demonstrated. In this work, we assessed ten different extracellular enzymatic activities involved in the wood decaying process including β-etherase that specifically cleaves the β-aryl ether linkages in the lignin polymer. For this purpose, a collection of 26 fungal strains, distributed within three ecological groups (white, brown and soft rot fungi), has been used. Among the ten potential functional markers, the combinatorial use of only six of them allowed separation between the group of white and soft rot fungi from the brown rot fungi. Moreover, our results suggest that extracellular β-etherase is a rare and dispensable activity among the wood decay fungi. Finally, we propose that this set of markers could be useful for the analysis of fungal communities in functional and environmental studies, and for the selection of strains with biotechnological interests. Copyright © 2012 Elsevier B.V. All rights reserved.

Survey of Basal Stem Rot Disease on Oil Palms (Elaeis guineensis Jacq.) in Kebun Bukit Kijang,North Sumatera, Indonesia

NASA Astrophysics Data System (ADS)

Lisnawita; Hanum, H.; Tantawi, A. R.

2016-08-01

Basal stem rot disease caused by Ganoderma sp. is a significant disease on oil palm plantations in Indonesia, especially in North Sumatera. Currently, the pathogen does not only attack the plants that have produced (old plants) but also attacks the plants that have not produced in the first generation yet. A survey of the distribution of the basal stem rot disease in the plantation of the community has been completed in order to illustrate the distribution and the incidence of the basal stem rot disease in 5 locations of the oil palm plantation of the community in Desa Bukit Kijang, Region of Asahan, North Sumatera, Indonesia. From the research, it is revealed that the basal stem rot disease has spread to all of the observed locations with the level of disease incidence between 0.71% in Kebun Bukit Kijang 3 to 50% in the 17 years old oil palm in Kebun Bukit Kijang 4 and Bukit Kijang 5. The observable symptoms of the basal stem rot disease are chlorotic leaves, the appearance of fruiting body, collapsed plants, and the existence of holes on the basal stem. The incidence of basal stem rot disease is higher on land due to a high sand content (>50%).

21 CFR 520.2240b - Sulfaethoxypyridazine tablets.

Code of Federal Regulations, 2012 CFR

2012-04-01

... (pneumonia, shipping fever), foot rot, calf scours; as adjunctive therapy in septicemia accompanying mastitis... and pneumonia) caused by sulfonamide-susceptible pathogens (E. coli, streptococci, staphylococci...

21 CFR 520.2240b - Sulfaethoxypyridazine tablets.

Code of Federal Regulations, 2013 CFR

2013-04-01

... (pneumonia, shipping fever), foot rot, calf scours; as adjunctive therapy in septicemia accompanying mastitis... and pneumonia) caused by sulfonamide-susceptible pathogens (E. coli, streptococci, staphylococci...

21 CFR 520.2240b - Sulfaethoxypyridazine tablets.

Code of Federal Regulations, 2014 CFR

2014-04-01

... (pneumonia, shipping fever), foot rot, calf scours; as adjunctive therapy in septicemia accompanying mastitis... and pneumonia) caused by sulfonamide-susceptible pathogens (E. coli, streptococci, staphylococci...

Effect of some Evaporation Matters on Storability of Sunflower ( Helianthus annuus L.) Seed.

PubMed

El-Saidy, Aml E A; El-Hai, K M Abd

This study focuses on finding compounds that are safe to humans and environment, such as propionic and acetic acids that may provide an alternative control of seed-borne pathogens and decrease seed deterioration during storage. The objectives of this study were to reduce sunflower seed deterioration and improve the viability of sunflower seed using environmentally safe organic acids. Propionic and acetic acids were applied on sunflower seed at different concentrations under laboratory conditions during different storage periods. After 6 months storage period, the viability of sunflower seed as well as morphological and physiological characteristics of seedlings were evaluated under greenhouse conditions. Laboratory experiment was conducted in a factorial completely randomized design and randomized complete block design for greenhouse experiment. Propionic and acetic acids at different concentrations showed inhibitory effects on the presence of different fungal genera in all storage periods. Propionic acid was most effective followed by acetic acid. Increasing storage periods from 0-6 months significantly decreased germination percentage, germination energy, seedling characters, survived healthy seedlings and seed oil and protein percentages but dead and rotted seeds, as well as rotted seedlings were increased. Treating sunflower seeds with propionic acid (100%) improved germination criteria, seedling characters and seed chemical characters as well as survival seedlings and minimized the dead seeds, rotted seeds and rotted seedlings as compared with the control under all storage periods. Under greenhouse conditions, the maximum growth parameter and physiological characters (chlorophylls a, b, carotenoids and total phenols) were recorded from seed treated with 100% propionic acid after 6 months of storage. It may be concluded that propionic and acetic acids vapors can have considerable fungicidal activity against sunflower pathogens and improve seed viability. Therefore, it is recommended using 100% propionic acid to reduce deterioration and seed-borne pathogens of sunflower under storage conditions.

Biocontrol ability and putative mode of action of yeasts against Geotrichum citri-aurantii in citrus fruit.

PubMed

Ferraz, Luriany Pompeo; Cunha, Tatiane da; da Silva, Aline Caroline; Kupper, Katia Cristina

2016-01-01

Sour rot is a major postharvest disease of citrus fruit and is caused by the fungal pathogen Geotrichum citri-aurantii. A lack of chemicals certified for the control of this disease has led to the consideration of alternative methods and strategies, such as the use of yeasts as biocontrol agents. The purpose of the present study was to test the ability of yeasts isolated from leaves, flowers, fruit, and soil, and six Saccharomyces cerevisiae isolates to control citrus sour rot, to assess the mechanisms of action of the yeast isolates that were demonstrated to be effective for biocontrol, and to identify the most effective yeast isolates for the biocontrol of G. citri-aurantii. In in vivo assays, three yeast isolates (ACBL-23, ACBL-44, and ACBL-77) showed a potential for controlling sour rot in citrus fruits, both preventatively and curatively. Most of the eight yeast isolates that were assessed for a mechanism of action did not produce antifungal compounds in an amount sufficient to inhibit the growth of the pathogen. Additionally, nutrient competition among the yeast strains was not found to be a biocontrol strategy. Instead, killer activity and hydrolytic enzyme production were identified as the major mechanisms involved in the biocontrol activity of the yeasts. Isolates ACBL-23, ACBL-44, and ACBL-77, which controlled sour rot most effectively, were identified as Rhodotorula minuta, Candida azyma, and Aureobasidium pullulans, respectively. To our knowledge, this is the first report of the potential of C. azyma as a biological control agent against a postharvest pathogen and its ability to produce a killer toxin. Copyright © 2016 Elsevier GmbH. All rights reserved.

Specificity of monoclonal antibodies to strains of Dickeya sp. that cause bacterial heart rot of pineapple.

PubMed

Peckham, Gabriel D; Kaneshiro, Wendy S; Luu, Van; Berestecky, John M; Alvarez, Anne M

2010-10-01

During a severe outbreak of bacterial heart rot that occurred in pineapple plantations on Oahu, Hawaii, in 2003 and years following, 43 bacterial strains were isolated from diseased plants or irrigation water and identified as Erwinia chrysanthemi (now Dickeya sp.) by phenotypic, molecular, and pathogenicity assays. Rep-PCR fingerprint patterns grouped strains from pineapple plants and irrigation water into five genotypes (A-E) that differed from representatives of other Dickeya species, Pectobacterium carotovorum and other enteric saprophytes isolated from pineapple. Monoclonal antibodies produced following immunization of mice with virulent type C Dickeya sp. showed only two specificities. MAb Pine-1 (2D11G1, IgG1 with kappa light chain) reacted to all 43 pineapple/water strains and some reference strains (D. dianthicola, D. chrysanthemi, D. paradisiaca, some D. dadantii, and uncharacterized Dickeya sp.) but did not react to reference strains of D. dieffenbachiae, D. zeae, or one of the two Malaysian pineapple strains. MAb Pine-2 (2A7F2, IgG3 with kappa light chain) reacted to all type B, C, and D strains but not to any A or E strains or any reference strains except Dickeya sp. isolated from Malaysian pineapple. Pathogenicity tests showed that type C strains were more aggressive than type A strains when inoculated during cool months. Therefore, MAb Pine-2 distinguishes the more virulent type C strains from less virulent type A pineapple strains and type E water strains. MAbs with these two specificities enable development of rapid diagnostic tests that will distinguish the systemic heart rot pathogen from opportunistic bacteria associated with rotted tissues. Use of the two MAbs in field assays also permits the monitoring of a known subpopulation and provides additional decision tools for disease containment and management practices.

Identification and Differentiation of Monilinia Species Causing Brown Rot of Pome and Stone Fruit using High-Resolution Melting (HRM) Analysis.

PubMed

Papavasileiou, Antonios; Madesis, Panagiotis B; Karaoglanidis, George S

2016-09-01

Brown rot is a devastating disease of stone fruit caused by Monilinia spp. Among these species, Monilinia fructicola is a quarantine pathogen in Europe but has recently been detected in several European countries. Identification of brown rot agents relies on morphological differences or use of molecular methods requiring fungal isolation. The current study was initiated to develop and validate a high-resolution melting (HRM) method for the identification of the Monilinia spp. and for the detection of M. fructicola among other brown rot pathogens. Based on the sequence of the cytb intron from M. laxa, M. fructicola, M. fructigena, M. mumecola, M. linhartiana, and M. yunnanensis isolates originating from several countries, a pair of universal primers for species identification and a pair of primers specific to M. fructicola were designed. The specificity of the primers was verified to ensure against cross-reaction with other fungal species. The melting curve analysis using the universal primers generated six different HRM curve profiles, each one specific for each species. Τhe HRM analysis primers specific to M. fructicola amplified a 120-bp region with a distinct melt profile corresponding to the presence of M. fructicola, regardless of the presence of other species. HRM analysis can be a useful tool for rapid identification and differentiation of the six Monilinia spp. using a single primer pair. This novel assay has the potential for simultaneous identification and differentiation of the closely related Monilinia spp. as well as for the differentiation of M. fructicola from other common pathogens or saprophytes that may occur on the diseased fruit.

Influence of Peanut Cultivars and Environmental Conditions on the Diversity and Community Composition of Pod Rot Soil Fungi in China.

PubMed

Wang, Mian; Chen, Mingna; Yang, Zhen; Chen, Na; Chi, Xiaoyuan; Pan, Lijuan; Wang, Tong; Yu, Shanlin; Guo, Xingqi

2017-12-01

Peanut yield and quality are seriously affected by pod rot pathogens worldwide, especially in China in recent years. The goals of this study are to analyze the structure of fungal communities of peanut pod rot in soil in three peanut cultivars and the correlation of pod rot with environmental variables using 454 pyrosequencing. A total of 46,723 internal transcribed spacer high-quality sequences were obtained and grouped into 1,706 operational taxonomic units at the 97% similarity cut-off level. The coverage, rank abundance, and the Chao 1 and Shannon diversity indices of the operational taxonomic units were analyzed. Members of the phylum Ascomycota were dominant, such as Fusarium , Chaetomium , Alternaria , and Sordariomycetes , followed by Basidiomycota. The results of the heatmap and redundancy analysis revealed significant variation in the composition of the fungal community among the three cultivar samples. The environmental conditions in different peanut cultivars may also influence on the structure of the fungal community. The results of this study suggest that the causal agent of peanut pod rot may be more complex, and cultivars and environmental conditions are both important contributors to the community structure of peanut pod rot fungi.

Effects of pre- and post-harvest application of selenium on inducing disease resistance and selenium accumulation in fruits

USDA-ARS?s Scientific Manuscript database

Botrytis cinerea, a ubiquitous fungal pathogen, causes severe damage (gray mold rot) on a large number of economically important fruits, vegetables, and ornamental crops at both pre- and post-harvest, which renders fruits unmarketable. Penicillium expansum is a widely spread fungal pathogen that cau...

Structure of Rot, a global regulator of virulence genes in Staphylococcus aureus.

PubMed

Zhu, Yuwei; Fan, Xiaojiao; Zhang, Xu; Jiang, Xuguang; Niu, Liwen; Teng, Maikun; Li, Xu

2014-09-01

Staphylococcus aureus is a highly versatile pathogen that can infect human tissue by producing a large arsenal of virulence factors that are tightly regulated by a complex regulatory network. Rot, which shares sequence similarity with SarA homologues, is a global regulator that regulates numerous virulence genes. However, the recognition model of Rot for the promoter region of target genes and the putative regulation mechanism remain elusive. In this study, the 1.77 Å resolution X-ray crystal structure of Rot is reported. The structure reveals that two Rot molecules form a compact homodimer, each of which contains a typical helix-turn-helix module and a β-hairpin motif connected by a flexible loop. Fluorescence polarization results indicate that Rot preferentially recognizes AT-rich dsDNA with ~30-base-pair nucleotides and that the conserved positively charged residues on the winged-helix motif are vital for binding to the AT-rich dsDNA. It is proposed that the DNA-recognition model of Rot may be similar to that of SarA, SarR and SarS, in which the helix-turn-helix motifs of each monomer interact with the major grooves of target dsDNA and the winged motifs contact the minor grooves. Interestingly, the structure shows that Rot adopts a novel dimerization model that differs from that of other SarA homologues. As expected, perturbation of the dimer interface abolishes the dsDNA-binding ability of Rot, suggesting that Rot functions as a dimer. In addition, the results have been further confirmed in vivo by measuring the transcriptional regulation of α-toxin, a major virulence factor produced by most S. aureus strains.

Registration of ‘Puma’ soft white winter wheat

USDA-ARS?s Scientific Manuscript database

Resistance to strawbreaker foot rot (caused by Oculimacula yallundae Crous & W. Gams and O. acuformis Crous & W. Gams), stripe rust (caused by Puccinia striiformis Westend. f. sp. tritici Eriks.), and Cephalosporium stripe (caused by Cephalosporium gramineum Nisikado and Ikata) are important traits ...

Combination of RNAseq and SNP nanofluidic array reveals the center of genetic diversity of cacao pathogen Moniliophthora roreri in the upper Magdalena Valley of Colombia and its clonality

USDA-ARS?s Scientific Manuscript database

Moniliophthora roreri is the fungal pathogen that causes frosty pod rot (FPR) disease of Theobroma cacao L., the source of chocolate. FPR occurs in most of the cacao producing countries in the Western Hemisphere, causing yield losses up to 80%. Genetic diversity within the FPR pathogen population ma...

Overexpression of BSR1 confers broad-spectrum resistance against two bacterial diseases and two major fungal diseases in rice

PubMed Central

Maeda, Satoru; Hayashi, Nagao; Sasaya, Takahide; Mori, Masaki

2016-01-01

Broad-spectrum disease resistance against two or more types of pathogen species is desirable for crop improvement. In rice, Xanthomonas oryzae pv. oryzae (Xoo), the causal bacteria of rice leaf blight, and Magnaporthe oryzae, the fungal pathogen causing rice blast, are two of the most devastating pathogens. We identified the rice BROAD-SPECTRUM RESISTANCE 1 (BSR1) gene for a BIK1-like receptor-like cytoplasmic kinase using the FOX hunting system, and demonstrated that BSR1-overexpressing (OX) rice showed strong resistance to the bacterial pathogen, Xoo and the fungal pathogen, M. oryzae. Here, we report that BSR1-OX rice showed extended resistance against two other different races of Xoo, and to at least one other race of M. oryzae. In addition, the rice showed resistance to another bacterial species, Burkholderia glumae, which causes bacterial seedling rot and bacterial grain rot, and to Cochliobolus miyabeanus, another fungal species causing brown spot. Furthermore, BSR1-OX rice showed slight resistance to rice stripe disease, a major viral disease caused by rice stripe virus. Thus, we demonstrated that BSR1-OX rice shows remarkable broad-spectrum resistance to at least two major bacterial species and two major fungal species, and slight resistance to one viral pathogen. PMID:27436950

Overexpression of BSR1 confers broad-spectrum resistance against two bacterial diseases and two major fungal diseases in rice.

PubMed

Maeda, Satoru; Hayashi, Nagao; Sasaya, Takahide; Mori, Masaki

2016-06-01

Broad-spectrum disease resistance against two or more types of pathogen species is desirable for crop improvement. In rice, Xanthomonas oryzae pv. oryzae (Xoo), the causal bacteria of rice leaf blight, and Magnaporthe oryzae, the fungal pathogen causing rice blast, are two of the most devastating pathogens. We identified the rice BROAD-SPECTRUM RESISTANCE 1 (BSR1) gene for a BIK1-like receptor-like cytoplasmic kinase using the FOX hunting system, and demonstrated that BSR1-overexpressing (OX) rice showed strong resistance to the bacterial pathogen, Xoo and the fungal pathogen, M. oryzae. Here, we report that BSR1-OX rice showed extended resistance against two other different races of Xoo, and to at least one other race of M. oryzae. In addition, the rice showed resistance to another bacterial species, Burkholderia glumae, which causes bacterial seedling rot and bacterial grain rot, and to Cochliobolus miyabeanus, another fungal species causing brown spot. Furthermore, BSR1-OX rice showed slight resistance to rice stripe disease, a major viral disease caused by rice stripe virus. Thus, we demonstrated that BSR1-OX rice shows remarkable broad-spectrum resistance to at least two major bacterial species and two major fungal species, and slight resistance to one viral pathogen.

Genome-Wide Association Study on Resistance to Stalk Rot Diseases in Grain Sorghum

PubMed Central

Adeyanju, Adedayo; Little, Christopher; Yu, Jianming; Tesso, Tesfaye

2015-01-01

Stalk rots are important biotic constraints to sorghum production worldwide. Several pathogens may be associated with the disease, but Macrophomina phaseolina and Fusarium thapsinum are recognized as the major causal organisms. The diseases become more aggressive when drought and high-temperature stress occur during grain filling. Progress in genetic improvement efforts has been slow due to lack of effective phenotyping protocol and the strong environmental effect on disease incidence and severity. Deployment of modern molecular tools is expected to accelerate efforts to develop resistant hybrids. This study was aimed at identifying genomic regions associated with resistance to both causal organisms. A sorghum diversity panel consisting of 300 genotypes assembled from different parts of the world was evaluated for response to infection by both pathogens. Community resources of 79,132 single nucleotide polymorphic (SNP) markers developed on the panel were used in association studies using a multi-locus mixed model to map loci associated with stalk rot resistance. Adequate genetic variation was observed for resistance to both pathogens. Structure analysis grouped the genotypes into five subpopulations primarily based on the racial category of the genotypes. Fourteen loci and a set of candidate genes appear to be involved in connected functions controlling plant defense response. However, each associated SNP had relatively small effect on the traits, accounting for 19–30% of phenotypic variation. Linkage disequilibrium analyses suggest that significant SNPs are genetically independent. Estimation of frequencies of associated alleles revealed that durra and caudatum subpopulations were enriched for resistant alleles, but the results suggest complex molecular mechanisms underlying resistance to both pathogens. PMID:25882062

Comparative genomics of maize ear rot pathogens reveals expansion of carbohydrate-active enzymes and secondary metabolism backbone genes in Stenocarpella maydis.

PubMed

Zaccaron, Alex Z; Woloshuk, Charles P; Bluhm, Burton H

2017-11-01

Stenocarpella maydis is a plant pathogenic fungus that causes Diplodia ear rot, one of the most destructive diseases of maize. To date, little information is available regarding the molecular basis of pathogenesis in this organism, in part due to limited genomic resources. In this study, a 54.8 Mb draft genome assembly of S. maydis was obtained with Illumina and PacBio sequencing technologies, and analyzed. Comparative genomic analyses with the predominant maize ear rot pathogens Aspergillus flavus, Fusarium verticillioides, and Fusarium graminearum revealed an expanded set of carbohydrate-active enzymes for cellulose and hemicellulose degradation in S. maydis. Analyses of predicted genes involved in starch degradation revealed six putative α-amylases, four extracellular and two intracellular, and two putative γ-amylases, one of which appears to have been acquired from bacteria via horizontal transfer. Additionally, 87 backbone genes involved in secondary metabolism were identified, which represents one of the largest known assemblages among Pezizomycotina species. Numerous secondary metabolite gene clusters were identified, including two clusters likely involved in the biosynthesis of diplodiatoxin and chaetoglobosins. The draft genome of S. maydis presented here will serve as a useful resource for molecular genetics, functional genomics, and analyses of population diversity in this organism. Copyright © 2017 British Mycological Society. Published by Elsevier Ltd. All rights reserved.

Plant growth and resistance promoted by Streptomyces spp. in tomato.

PubMed

Dias, Maila P; Bastos, Matheus S; Xavier, Vanessa B; Cassel, Eduardo; Astarita, Leandro V; Santarém, Eliane R

2017-09-01

Plant Growth Promoting Rhizobacteria (PGPR) represent an alternative to improve plant growth and yield as well as to act as agents of biocontrol. This study characterized isolates of Streptomyces spp. (Stm) as PGPR, determined the antagonism of these isolates against Pectobacterium carotovorum subsp. brasiliensis (Pcb), evaluated the ability of Stm on promoting growth and modulating the defense-related metabolism of tomato plants, and the potential of Stm isolates on reducing soft rot disease in this species. The VOC profile of Stm was also verified. Promotion of plant growth was assessed indirectly through VOC emission and by direct interaction with Stm isolates in the roots. Evaluation of soft rot disease was performed in vitro on plants treated with Stm and challenged with Pcb. Enzymes related to plant defense were then analyzed in plants treated with three selected isolates of Stm, and PM1 was chosen for further Pcb-challenging experiment. Streptomyces spp. isolates displayed characteristics of PGPR. PM3 was the isolate with efficient antagonism against Pcb by dual-culture. Most of the isolates promoted growth of root and shoot of tomato plants by VOC, and PM5 was the isolate that most promoted growth by direct interaction with Stm. Soft rot disease and mortality of plants were significantly reduced when plants were treated with StmPM1. Modulation of secondary metabolism was observed with Stm treatment, and fast response of polyphenoloxidases was detected in plants pretreated with StmPM1 and challenged with Pcb. Peroxidase was significantly activated three days after infection with Pcb in plants pretreated with StmPM1. Results suggest that Streptomyces sp. PM1 and PM5 have the potential to act as PGPR. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Indirect selection for resistance to ear rot and leaf diseases in maize lines using biplots.

PubMed

Pereira, G S; Camargos, R B; Balestre, M; Von Pinho, R G; C Melo, W M

2015-09-21

Leaf disease and ear rot have caused reductions in maize yield in Brazil and other producer countries. Therefore, the aims of this study were to analyze the association between husked ear yield and the severity of maize white spot, gray leaf spot, helminthosporium, and ear rot caused by Fusarium verticillioides and Diplodia maydis using biplots in a mixed-model approach. The responses of 238 lines introduced to Brazil and four controls were evaluated using an incomplete block design with three replicates in two locations: Lavras and Uberlândia, Minas Gerais, Brazil. Two experiments were conducted in each location, one with F. verticillioides and the other with D. maydis. The mixed models elucidated the relationship between yield, leaf disease, and ear disease. Significant genotype x environment and genotype x pathogen interactions were observed. In conclusion, husked ear yield is more associated with ear rot than with the leaf diseases evaluated, justifying the indirect selection for resistance to kernel rot in maize-F. verticillioides and maize-D. maydis pathosystems by yield evaluation.

Specific detection of Pectobacterium carotovorum by loop-mediated isothermal amplification.

PubMed

Yasuhara-Bell, Jarred; Marrero, Glorimar; De Silva, Asoka; Alvarez, Anne M

2016-12-01

Potatoes are an important agroeconomic crop worldwide and maceration diseases caused by pectolytic bacterial pathogens result in significant pre- and post-harvest losses. Pectobacterium carotovorum shares a common host range with other Pectobacterium spp. and other members of the Enterobacteriaceae, such as Dickeya spp. As these pathogens cannot be clearly differentiated on the basis of the symptoms they cause, improved methods of identification are critical for the determination of sources of contamination. Current standardized methods for the differentiation of pectolytic species are time consuming and require trained personnel, as they rely on traditional bacteriological practices that do not always produce conclusive results. In this growing world market, there is a need for rapid diagnostic tests that can differentiate between pectolytic pathogens, as well as separate them from non-pectolytic enteric bacteria associated with soft rots of potato. An assay has been designed previously to detect the temperate pathogen Pectobacterium atrosepticum, but there is currently no recognized rapid assay for the detection of the tropical/subtropical counterpart, Pectobacterium carotovorum. This report describes the development of a loop-mediated isothermal amplification (LAMP) assay that detects P. carotovorum with high specificity. The assay was evaluated using all known species of Pectobacterium and only showed positive reactions for P. carotovorum. This assay was also tested against 15 non-target genera of plant-associated bacteria and did not produce any false positives. The LAMP assay described here can be used as a rapid test for the differentiation of P. carotovorum from other pectolytic pathogens, and its gene target can be the basis for the development of other molecular-based detection assays. © 2016 BSPP and John Wiley & Sons Ltd.

Pectobacterium polaris sp. nov., isolated from potato (Solanum tuberosum).

PubMed

Dees, Merete Wiken; Lysøe, Erik; Rossmann, Simeon; Perminow, Juliana; Brurberg, May Bente

2017-12-01

The genus Pectobacterium, which belongs to the bacterial family Enterobacteriaceae, contains numerous species that cause soft rot diseases in a wide range of plants. The species Pectobacterium carotovorum is highly heterogeneous, indicating a need for re-evaluation and a better classification of the species. PacBio was used for sequencing of two soft-rot-causing bacterial strains (NIBIO1006 T and NIBIO1392), initially identified as P. carotovorumstrains by fatty acid analysis and sequencing of three housekeeping genes (dnaX, icdA and mdh). Their taxonomic relationship to other Pectobacterium species was determined and the distance from any described species within the genus Pectobacterium was less than 94 % average nucleotide identity (ANI). Based on ANI, phylogenetic data and genome-to-genome distance, strains NIBIO1006 T , NIBIO1392 and NCPPB3395 are suggested to represent a novel species of the genus Pectobacterium, for which the name Pectobacterium polaris sp. nov. is proposed. The type strain is NIBIO1006 T (=DSM 105255 T =NCPPB 4611 T ).

Production of cell wall-degrading enzymes by Aspergillus nidulans: a model system for fungal pathogenesis of plants.

PubMed Central

Dean, R A; Timberlake, W E

1989-01-01

The cell wall-degrading enzymes polygalacturonase and pectate lyase have been suggested to be crucial for penetration and colonization of plant tissues by some fungal pathogens. We have found that Aspergillus nidulans (= Emericella nidulans), a saprophytic Ascomycete, produces levels of these enzymes equal to those produced by soft-rotting Erwinia species. Induction of polygacturonase and pectate lyase in A. nidulans requires substrate and is completely repressed by glucose. Surprisingly, inoculation of excised plant tissues with A. nidulans conidia leads to formation of necrotic, water-soaked lesions within which the organism sporulates. Thus, A. nidulans has phytopathogenic potential. The release of glucose and other sugars from wounded tissues may repress pectolytic enzyme production and limit disease development. Therefore, we tested creA204, a mutation that relieves glucose repression of some A. nidulans carbon utilization enzymes, for its effect on production of pectolytic enzymes. creA204 failed to relieve catabolite repression of polygalacturonase or pectate lyase and had no effect on disease severity. PMID:2535501

Occurrence of Internal Stipe Necrosis of Cultivated Mushrooms (Agaricus bisporus) Caused by Ewingella americana in Korea

PubMed Central

Jhune, Chang-Sung; Cheong, Jong-Chun; Yun, Hyung-Sik; Cho, Weon-Dae

2009-01-01

The internal stipe necrosis of cultivated mushrooms (Agaricus bisporus) is caused by the bacterium Ewingella americana, a species of the Enterobacteriaceae. Recently, Ewingella americana was isolated from cultivated white button mushrooms in Korea evidencing symptoms of internal stipe browning. Its symptoms are visible only at harvest, and appear as a variable browning reaction in the center of the stipes. From these lesions, we isolated one bacterial strain (designated CH4). Inoculation of the bacterial isolate into mushroom sporocarps yielded the characteristic browning symptoms that were distinguishable from those of the bacterial soft rot that is well known to mushroom growers. The results of Gram stain, flagellal staining, and biochemical tests identified these isolates as E. americana. This was verified by pathogenicity, physiological and biochemical characteristics, and the results of an analysis of the 16S rRNA gene sequences and the fatty acids profile. This is the first report of the isolation of E. americana from cultivated white button mushrooms in Korea. PMID:23983509

Low doses of gamma radiation in the management of postharvest Lasiodiplodia theobromae in mangos

PubMed Central

Santos, Alice Maria Gonçalves; Lins, Severina Rodrigues Oliveira; da Silva, Josenilda Maria; de Oliveira, Sônia Maria Alves

2015-01-01

The postharvest life of mango is limited by the development of pathogens, especially fungi that cause rot, among which stands out the Lasiodiplodia theobromae. Several control methods have been employed to minimize the damages caused by this fungus, chemical control can leave residues to man and nature; physical control by the use of gamma radiation in combination with modified atmosphere and cold storage. The use of gamma radiation helps to reduce the severity of the pathogen assist in the ripening process of fruits, even at low doses (0.25, 0.35 and 0.45 kGy) chemical properties such as pH, soluble solids, acid ascorbic, titratable acidity and also the quality parameters of the pulp showed no damage that are ideal for trade and consumption of mangoes. This treatment can be extended for use in the management of diseases such as natural infections for penducular rot complex that has as one of L. theobroma pathogens involved. PMID:26413068

Inferences on the phylogeography of the fungal pathogen Heterobasidion annosum, including evidence of interspecific horizontal genetic transfer and of human-mediated, long-range dispersal

Treesearch

R.E. Linzer; W.J. Otrosina; P. Gonthier; J. Bruhn; G. Laflamme; G. Bussieres; M. Garbelotto

2008-01-01

Fungi in the basidiomycete species complex Heterobasidion annosum are significant root-rot pathogens of conifers throughout the northern hemisphere. We utilize a multilocus phylogenetic approach to examine hypotheses regarding the evolution and divergence of two Heterobasidion taxa associated with pines: the Eurasian H. ...

Aggressive root pathogen Phellinus noxius and implications for western Pacific Islands

Treesearch

Sara M. Ashiglar; Phil G. Cannon; Ned B. Klopfenstein

2015-01-01

Phellinus noxius is an aggressive root rot pathogen affecting tropical and subtropical forests. Causing much damage in tropical Asia, Africa, Taiwan, Japan and the Pacific Islands, its wide host range encompasses more than 200 plant species representing 59 families (Ann et al. 2002). It can devastate agricultural plantations of tea, rubber, cocoa, avocados,...

Identification of Rhizopus stolonifer as a Pre-emergence Seedling Disease Pathogen of Beta vulgaris

USDA-ARS?s Scientific Manuscript database

Rhizopus stolonifer, a common soil borne fungus in Michigan, is a known root rot pathogen on mature sugar beet. In 2008, Rs was isolated from a sugar beet seed lot showing consistently low germination rates in both the field and lab, and Rs was morphologically identified on malt extract agar. Much o...

Influence of cultural practices on edaphic factors related to root disease in Pinus nursery seedlings

Treesearch

J Juzwik; K. M. Gust; R. R. Allmaras

1999-01-01

Conifer seedlings grown in bare-root nurseries are frequently damaged and destroyed by soil-borne pathogenic fungi that cause root rot. Relationships between nursery cultural practices, soils characteristics, and populations of potential pathogens in the soil were examined in three bare-root tree nurseries in the midwestern USA. Soil-borne populations of ...

Cyclopiazonic acid is a pathogenicity factor for Aspergillus flavus and a promising target for screening germplasm for ear rot resistance

USDA-ARS?s Scientific Manuscript database

Aspergillus flavus, an opportunistic pathogen, contaminates maize and other key crops with carcinogenic aflatoxins (AF). Besides AF, A. flavus makes many more secondary metabolites (SMs), whose toxicity in insects or vertebrates has been studied. However, the role of SMs in the invasion of plant hos...

Cyclopiazonic Acid Is a Pathogenicity Factor for Aspergillus flavus and a Promising Target for Screening Germplasm for Ear Rot Resistance.

PubMed

Chalivendra, Subbaiah C; DeRobertis, Catherine; Chang, Perng-Kuang; Damann, Kenneth E

2017-05-01

Aspergillus flavus, an opportunistic pathogen, contaminates maize and other key crops with carcinogenic aflatoxins (AFs). Besides AFs, A. flavus makes many more secondary metabolites (SMs) whose toxicity in insects or vertebrates has been studied. However, the role of SMs in the invasion of plant hosts by A. flavus remains to be investigated. Cyclopiazonic acid (CPA), a neurotoxic SM made by A. flavus, is a nanomolar inhibitor of endoplasmic reticulum calcium ATPases (ECAs) and a potent inducer of cell death in plants. We hypothesized that CPA, by virtue of its cytotoxicity, may serve as a key pathogenicity factor that kills plant cells and supports the saprophytic life style of the fungus while compromising the host defense response. This proposal was tested by two complementary approaches. A comparison of CPA levels among A. flavus isolates indicated that CPA may be a determinant of niche adaptation, i.e., isolates that colonize maize make more CPA than those restricted only to the soil. Further, mutants in the CPA biosynthetic pathway are less virulent in causing ear rot than their wild-type parent in field inoculation assays. Additionally, genes encoding ECAs are expressed in developing maize seeds and are induced by A. flavus infection. Building on these results, we developed a seedling assay in which maize roots were exposed to CPA, and cell death was measured as Evans Blue uptake. Among >40 maize inbreds screened for CPA tolerance, inbreds with proven susceptibility to ear rot were also highly CPA sensitive. The publicly available data on resistance to silk colonization or AF contamination for many of the lines was also broadly correlated with their CPA sensitivity. In summary, our studies show that i) CPA serves as a key pathogenicity factor that enables the saprophytic life style of A. flavus and ii) maize inbreds are diverse in their tolerance to CPA. Taking advantage of this natural variation, we are currently pursuing both genome-wide and candidate gene approaches to identify novel components of maize resistance to Aspergillus ear rot.

Potential Reasons for Prevalence of Fusarium Wilt in Oriental Melon in Korea

PubMed Central

Seo, Yunhee; Kim, Young Ho

2017-01-01

This study aims to examine the potential reasons for the current prevalence of the fusarium wilt in the oriental melon. Twenty-seven Fusarium isolates obtained from oriental melon greenhouses in 2010–2011 were identified morphologically and by analysis of elongation factor-1 alpha gene (EF-1α) and internal transcribed spacer (ITS) rDNA sequences as 6 Fusarium species (8 isolates of F. oxysporum, 8 F. commune, 5 F. proliferatum, 3 F. equiseti, 2 F. delphinoides, and 1 F. andiyazi), which were classified as same into 6 EF-1α sequence-based phylogenetic clades. Pathogenicity of the Fusarium isolates on the oriental melon was highest in F. proliferatum, next in F. oxysporum and F. andiyazi, and lowest in the other Fusarium species tested, suggesting F. proliferatum and F. oxysporum were major pathogens of the oriental melon, inducing stem rots and vascular wilts, respectively. Oriental melon and watermelon were more susceptible to F. oxysporum than shintosa and cucumber; and cucumber was most, oriental melon and watermelon, medially, and shintosa was least susceptible to F. proliferatum, whose virulence varied among and within their phylogenetic subclades. Severe root-knot galls were formed on all the crops infected with Meloidogyne incognita; however, little indication of vascular wilts or stem and/or root rots was shown by the nematode infection. These results suggest the current fungal disease in the oriental melon may be rarely due to virulence changes of the fusarium wilt pathogen and the direct cause of the severe root-knot nematode infection, but may be potentially from other Fusarium pathogen infection that produces seemingly wilting caused by severe stem rotting. PMID:28592944

Detection of Dichelobacter nodosus in wild ungulates (Capra ibex ibex and Ovis aries musimon) and domestic sheep suffering from foot rot using a two-step polymerase chain reaction.

PubMed

Belloy, Luc; Giacometti, Marco; Boujon, Patrick; Waldvogel, Andreas

2007-01-01

Severe keratinous hoof afflictions have been recorded in ibex (Capra ibex ibex) since 1995 and more recently in mouflon (Ovis aries musimon) in Switzerland. Based on clinical observations and comparison with diseases known to affect domestic ungulates, it was hypothesized these wild ungulates were affected by foot rot associated with infection with Dichelobacter nodosus. Dichelobacter nodosus has been shown to be the essential pathogen for initiation and establishment of foot rot, a highly contagious foot disease of sheep and goats. Because these bacteria could not be cultivated from affected ibex, we developed a nested polymerase chain reaction that allowed detection of D. nodosus without culture. Using this assay, we were able to diagnose D. nodosus infections of ibex, mouflon, and domestic sheep in natural outbreaks. From these results we conclude that D. nodosus plays an etiological role in foot rot not only in domestic but also in wild Caprinae.

Unravelling the Phellinus pini s.l. complex in North America: a multilocus phylogeny and differentiation analysis of Porodaedalea

Treesearch

N.J. Brazee; D.L. Lindner

2013-01-01

Phellinus sensu lato (s.l.) is a complex of segregate genera that act as aggressive pathogens of woody plants. Nearly all of the genera in this complex have unresolved taxonomies, including Porodaedalea, which is one of the most important trunk rot pathogens of coniferous trees throughout the northern hemisphere. In an attempt...

Phellinus noxius in Guam, Saipan, Yap, Palau, Pohnpei and Kosrae [Chapter IV

Treesearch

Phil G. Cannon; Ned B. Klopfenstein; Mee-Sook Kim; Yuko Ota; Norio Sahashi; Robert L. Schlub; Gibson Santos; Rodasio Samuel; Francis Ruegorong; Maxson Nithan; Blair Charley; Erick Waguk; Roland Quitugua; Ashley Lehman; Konrad Engleberger; Victor Guerrero; Sid Cabrerra; Manny Tenorio; Arnold Route

2014-01-01

Phellinus noxius has a reputation of being an aggressive root rot pathogen on many forest tree species in parts of Southeast Asia and its symptoms and signs have been well documented. Previous reports from Micronesia indicated that this fungal pathogen is responsible for considerable damage in Saipan and likely present in Kosrae and Pohnpei. In this present...

Fusarium agapanthi sp. nov, a novel bikaverin and fusarubin-producing leaf and stem spot pathogen of Agapanthus praecox (African lily) from Australia and Italy

USDA-ARS?s Scientific Manuscript database

This study was conducted to characterize a novel Fusarium species that caused leaf and stem spot on Agapanthus praecox (Agapanthus, African lily) in northern Italy and leaf rot and spot on the same host in Melbourne, Australia. Formally described as Fusarium agapanthi, this pathogen was analyzed usi...

Interactions between cranberries and fungi: the proposed function of organic acids in virulence suppression of fruit rot fungi

PubMed Central

Tadych, Mariusz; Vorsa, Nicholi; Wang, Yifei; Bergen, Marshall S.; Johnson-Cicalese, Jennifer; Polashock, James J.; White, James F.

2015-01-01

Cranberry fruit are a rich source of bioactive compounds that may function as constitutive or inducible barriers against rot-inducing fungi. The content and composition of these compounds change as the season progresses. Several necrotrophic fungi cause cranberry fruit rot disease complex. These fungi remain mostly asymptomatic until the fruit begins to mature in late August. Temporal fluctuations and quantitative differences in selected organic acid profiles between fruit of six cranberry genotypes during the growing season were observed. The concentration of benzoic acid in fruit increased while quinic acid decreased throughout fruit development. In general, more rot-resistant genotypes (RR) showed higher levels of benzoic acid early in fruit development and more gradual decline in quinic acid levels than that observed in the more rot-susceptible genotypes. We evaluated antifungal activities of selected cranberry constituents and found that most bioactive compounds either had no effects or stimulated growth or reactive oxygen species (ROS) secretion of four tested cranberry fruit rot fungi, while benzoic acid and quinic acid reduced growth and suppressed secretion of ROS by these fungi. We propose that variation in the levels of ROS suppressive compounds, such as benzoic and quinic acids, may influence virulence by the fruit rot fungi. Selection for crops that maintain high levels of virulence suppressive compounds could yield new disease resistant varieties. This could represent a new strategy for control of disease caused by necrotrophic pathogens that exhibit a latent or endophytic phase. PMID:26322038

Protection of turmeric plants from rhizome rot disease under field conditions by β-D-glucan nanoparticle.

PubMed

Anusuya, Sathiyanarayanan; Sathiyabama, Muthukrishnan

2015-01-01

The rhizome rot caused by Pythium aphanidermatum is one of the most devastating diseases of the turmeric crop. Fungicides are unable to control the rapidly evolving P. aphanidermatum and new control strategies are urgently needed. This study examined the effect of β-d-glucan nanoparticles (GNP) in turmeric plants under field condition by the foliar spray method. Enhanced plant growth, rhizome yield, and curcumin content demonstrate the positive effect of the GNP on turmeric plants. Rapid activation of various defense enzymes was also observed in leaves and rhizomes of treated plants. GNP-treated plants showed a decreased rot incidence. It may be possible that increased defense enzymes might have played a role in reducing the colonization of pathogen. Copyright © 2015 Elsevier B.V. All rights reserved.

The Fusarium crown rot pathogen Fusarium pseudograminearum triggers a suite of transcriptional and metabolic changes in bread wheat (Triticum aestivum L.)

PubMed Central

Carere, Jason; Fitzgerald, Timothy L.; Stiller, Jiri; Covarelli, Lorenzo; Xu, Qian; Gubler, Frank; Colgrave, Michelle L.; Gardiner, Donald M.; Manners, John M.; Henry, Robert J.; Kazan, Kemal

2017-01-01

Abstract Background and Aims Fusarium crown rot caused by the fungal pathogen Fusarium pseudograminearum is a disease of wheat and barley, bearing significant economic cost. Efforts to develop effective resistance to this disease have been hampered by the quantitative nature of resistance and a lack of understanding of the factors associated with resistance and susceptibility. Here, we aimed to dissect transcriptional responses triggered in wheat by F. pseudograminearum infection. Methods We used an RNA-seq approach to analyse host responses during a compatible interaction and identified >2700 wheat genes differentially regulated after inoculation with F. pseudograminearum. The production of a few key metabolites and plant hormones in the host during the interaction was also analysed. Key Results Analysis of gene ontology enrichment showed that a disproportionate number of genes involved in primary and secondary metabolism, signalling and transport were differentially expressed in infected seedlings. A number of genes encoding pathogen-responsive uridine-diphosphate glycosyltransferases (UGTs) potentially involved in detoxification of the Fusarium mycotoxin deoxynivalenol (DON) were differentially expressed. Using a F. pseudograminearum DON-non-producing mutant, DON was shown to play an important role in virulence during Fusarium crown rot. An over-representation of genes involved in the phenylalanine, tryptophan and tyrosine biosynthesis pathways was observed. This was confirmed through metabolite analyses that demonstrated tryptamine and serotonin levels are induced after F. pseudograminearum inoculation. Conclusions Overall, the observed host response in bread wheat to F. pseudograminearum during early infection exhibited enrichment of processes related to pathogen perception, defence signalling, transport and metabolism and deployment of chemical and enzymatic defences. Additional functional analyses of candidate genes should reveal their roles in disease resistance or susceptibility. Better understanding of host responses contributing to resistance and/or susceptibility will aid the development of future disease improvement strategies against this important plant pathogen. PMID:27941094

The Fusarium crown rot pathogen Fusarium pseudograminearum triggers a suite of transcriptional and metabolic changes in bread wheat (Triticum aestivum L.).

PubMed

Powell, Jonathan J; Carere, Jason; Fitzgerald, Timothy L; Stiller, Jiri; Covarelli, Lorenzo; Xu, Qian; Gubler, Frank; Colgrave, Michelle L; Gardiner, Donald M; Manners, John M; Henry, Robert J; Kazan, Kemal

2017-03-01

Fusarium crown rot caused by the fungal pathogen Fusarium pseudograminearum is a disease of wheat and barley, bearing significant economic cost. Efforts to develop effective resistance to this disease have been hampered by the quantitative nature of resistance and a lack of understanding of the factors associated with resistance and susceptibility. Here, we aimed to dissect transcriptional responses triggered in wheat by F. pseudograminearum infection. We used an RNA-seq approach to analyse host responses during a compatible interaction and identified >2700 wheat genes differentially regulated after inoculation with F. pseudograminearum . The production of a few key metabolites and plant hormones in the host during the interaction was also analysed. Analysis of gene ontology enrichment showed that a disproportionate number of genes involved in primary and secondary metabolism, signalling and transport were differentially expressed in infected seedlings. A number of genes encoding pathogen-responsive uridine-diphosphate glycosyltransferases (UGTs) potentially involved in detoxification of the Fusarium mycotoxin deoxynivalenol (DON) were differentially expressed. Using a F. pseudograminearum DON-non-producing mutant, DON was shown to play an important role in virulence during Fusarium crown rot. An over-representation of genes involved in the phenylalanine, tryptophan and tyrosine biosynthesis pathways was observed. This was confirmed through metabolite analyses that demonstrated tryptamine and serotonin levels are induced after F. pseudograminearum inoculation. Overall, the observed host response in bread wheat to F. pseudograminearum during early infection exhibited enrichment of processes related to pathogen perception, defence signalling, transport and metabolism and deployment of chemical and enzymatic defences. Additional functional analyses of candidate genes should reveal their roles in disease resistance or susceptibility. Better understanding of host responses contributing to resistance and/or susceptibility will aid the development of future disease improvement strategies against this important plant pathogen. © The Author 2016. Published by Oxford University Press on behalf of the Annals of Botany Company.

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

Hutton, D.

The reasons for preservative treatment of cooling tower wood are reviewed along with a summary of which types of treatment are available, how they are applied, and a comparison of materials and processes. Industries often specify minimum quality preservatives for their cooling towers without understanding the loss of strength caused by decay and the economic losses due to a cooling tower failure and lost production. Wood is subject to both chemical (surface delignification and iron rot) and biological (soft rot) attack. A successful preservative treatment that protects against both must have retention and penetration qualities. Research efforts are examining themore » toxicity and environmental impacts of preservatives and exploring the possibility of chemically modifying wood. (DCK)« less

Development of a rapid and simple Agrobacterium tumefaciens mediated transformation system for the fungal pathogen Heterobasidion annosum

Treesearch

Nicklas Samils; Malin Elfstrand; Daniel L. Lindner Czederpiltz; Jan Fahleson; Ake Olson; Christina Dixelius; Jan Stenlid

2006-01-01

Heterobasidion annosum causes root and butt-rot in trees and is the most serious forest pathogen in the northern hemisphere. We developed a rapid and simple Agrobacterium-mediated method of gene delivery into H. annosum to be used in functional studies of candidate genes and for visualization of mycelial interactions. Heterobasidion annosum TC 32-1 was cocultivated at...

Iron Deficiency Induced by Chrysobactin in Saintpaulia Leaves Inoculated with Erwinia chrysanthemi.

PubMed Central

Neema, C.; Laulhere, J. P.; Expert, D.

1993-01-01

In this communication, we examine the fate of iron during soft rot pathogenesis caused by Erwinia chrysanthemi on its host, Saintpaulia ionantha. The spread of soft rot caused by this enterobacterium was previously shown to depend on a functional genetic locus encoding a high-affinity iron assimilation system involving the catechol-type siderophore chrysobactin. Leaf intercellular fluid from healthy plants was analyzed with regard to the iron content and its availability for bacterial growth. It was compared to the fluid from diseased plants for the presence of strong iron ligands, using a new approach based on the iron-binding property of an ion-exchange resin. Further characterization allowed the identification of chrysobactin in diseased tissues, thus providing the first evidence for the external release of a microbial siderophore during pathogenesis. Competition for nutritional iron was also studied through a plant-bacterial cell system: iron incorporated into plant ferritin appeared to be considerably reduced in bacteria-treated suspension soybean cells. The same effect was visualized during treatment of soybean cells with axenic leaf intercellular fluid from E. chrysanthemi-inoculated saintpaulia leaves or with chrysobactin. PMID:12231882

Incidence of bacterial diseases associated with irrigation methods on onions (Allium cepa).

PubMed

Chorolque, A; Pozzo Ardizzi, C; Pellejero, G; Aschkar, G; García Navarro, F J; Jiménez Ballesta, R

2018-04-24

In the last decade, diseases of bacterial origin in onions have increased and this has led to significant losses in production. These diseases are currently observed in both the Old and New Worlds. The aim of the experimental work reported here was to evaluate whether the irrigation method influences the incidence of diseases of bacterial origin. In cases where the inoculum was natural, the initial incidence of Soft Bacterial Rot was not manifested in any treatment in the first year, whereas at the end of the conservation period all treatments had increased incidences of infection. Sprinkler irrigation (8%) was statistically differentiated from the other treatments, for which the final incidence was similar (4.5%). For all irrigation treatments, the final incidence of Bacterial Soft Rot decreased or remained stable towards the end of the cycle, with the exception of sprinkler irrigation in 2015, which increased. It can be inferred from the results that the irrigation method does have an influence on the incidence of diseases of bacterial origin in the post-harvest stage for onions. This article is protected by copyright. All rights reserved.

Etiology and Epidemiological Conditions Promoting Fusarium Root Rot in Sweetpotato.

PubMed

Scruggs, A C; Quesada-Ocampo, L M

2016-08-01

Sweetpotato production in the United States is limited by several postharvest diseases, and one of the most common is Fusarium root rot. Although Fusarium solani is believed to be the primary causal agent of disease, numerous other Fusarium spp. have been reported to infect sweetpotato. However, the diversity of Fusarium spp. infecting sweetpotato in North Carolina is unknown. In addition, the lack of labeled and effective fungicides for control of Fusarium root rot in sweetpotato creates the need for integrated strategies to control disease. Nonetheless, epidemiological factors that promote Fusarium root rot in sweetpotato remain unexplored. A survey of Fusarium spp. infecting sweetpotato in North Carolina identified six species contributing to disease, with F. solani as the primary causal agent. The effects of storage temperature (13, 18, 23, 29, and 35°C), relative humidity (80, 90, and 100%), and initial inoculum level (3-, 5-, and 7-mm-diameter mycelia plug) were examined for progression of Fusarium root rot caused by F. solani and F. proliferatum on 'Covington' sweetpotato. Fusarium root rot was significantly reduced (P < 0.05) at lower temperatures (13°C), low relative humidity levels (80%), and low initial inoculum levels for both pathogens. Sporulation of F. proliferatum was also reduced under the same conditions. Qualitative mycotoxin analysis of roots infected with one of five Fusarium spp. revealed the production of fumonisin B1 by F. proliferatum when infecting sweetpotato. This study is a step toward characterizing the etiology and epidemiology of Fusarium root rot in sweetpotato, which allows for improved disease management recommendations to limit postharvest losses to this disease.

Wheat crown rot pathogens Fusarium graminearum and F. pseudograminearum lack specialization.

PubMed

Chakraborty, Sukumar; Obanor, Friday; Westecott, Rhyannyn; Abeywickrama, Krishanthi

2010-10-01

This article reports a lack of pathogenic specialization among Australian Fusarium graminearum and F. pseudograminearum causing crown rot (CR) of wheat using analysis of variance (ANOVA), principal component and biplot analysis, Kendall's coefficient of concordance (W), and κ statistics. Overall, F. pseudograminearum was more aggressive than F. graminearum, supporting earlier delineation of the crown-infecting group as a new species. Although significant wheat line-pathogen isolate interaction in ANOVA suggested putative specialization when seedlings of 60 wheat lines were inoculated with 4 pathogen isolates or 26 wheat lines were inoculated with 10 isolates, significant W and κ showed agreement in rank order of wheat lines, indicating a lack of specialization. The first principal component representing nondifferential aggressiveness explained a large part (up to 65%) of the variation in CR severity. The differential components were small and more pronounced in seedlings than in adult plants. By maximizing variance on the first two principal components, biplots were useful for highlighting the association between isolates and wheat lines. A key finding of this work is that a range of analytical tools are needed to explore pathogenic specialization, and a statistically significant interaction in an ANOVA cannot be taken as conclusive evidence of specialization. With no highly resistant wheat cultivars, Fusarium isolates mostly differ in aggressiveness; however, specialization may appear as more resistant cultivars become widespread.

Antifungal metabolites (monorden, monocillins I, II, III) from Colletotrichum graminicola, a systemic vascular pathogen of maize.

PubMed

Wicklow, Donald T; Jordan, Annalisa M; Gloer, James B

2009-12-01

Colletotrichum graminicola is a systemic vascular pathogen that causes anthracnose stalk rot and leaf blight of maize. In the course of an effort to explore the potential presence and roles of C. graminicola metabolites in maize, ethyl acetate extracts of solid substrate fermentations of several C. graminicola isolates from Michigan and Illinois were found to be active against Aspergillus flavus and Fusarium verticillioides, both mycotoxin-producing seed-infecting fungal pathogens. Chemical investigations of the extract of one such isolate (NRRL 47511) led to the isolation of known metabolites monorden (also known as radicicol) and monocillins I-III as major components. Monorden and monocillin I displayed in vitro activity against the stalk- and ear-rot pathogen Stenocarpella maydis while only the most abundant metabolite (monorden) showed activity against foliar pathogens Alternaria alternata, Bipolaris zeicola, and Curvularia lunata. Using LC-HRESITOFMS, monorden was detected in steam-sterilized maize stalks and stalk residues inoculated with C. graminicola but not in the necrotic stalk tissues of wound-inoculated plants grown in an environmental chamber. Monorden and monocillin I can bind and inhibit plant Hsp90, a chaperone of R-proteins. It is hypothesized that monorden and monocillins could support the C. graminicola disease cycle by disrupting maize plant defenses and by excluding other fungi from necrotic tissues and crop residues. This is the first report of natural products from C. graminicola, as well as the production of monorden and monocillins by a pathogen of cereals.

A bionanohybrid ZnAl-NADS ecological pesticide as a treatment for soft rot disease in potato (Solanum tuberosum L.).

PubMed

Morales-Irigoyen, Erika Elizabeth; de Las Mercedes Gómez-Y-Gómez, Yolanda; Flores-Moreno, Jorge Luis; Franco-Hernández, Marina Olivia

2017-09-18

Pectobacterium carotovorum (Pc) is a phytopathogenic strain that causes soft rot disease in potato (Solanum tuberosum L.), resulting in postharvest losses. Chemical control is effective for managing this disease, but overdoses cause adverse effects. Because farmers insist on using chemical agents for crop protection, it is necessary to develop more effective pesticides in which the active compound released can be regulated. In this context, we proposed the synthesis of ZnAl-NADS, in which nalidixic acid sodium salt (NADS) is linked to a ZnAl-NO 3 layered double hydroxide (LDH) host as a nanocarrier. XRD, FT-IR, and SEM analyses confirmed the successful intercalation of NADS into the interplanar LDH space. The drug release profile indicated that the maximum release was completed in 70 or 170 min for free NADS (alone) or for NADS released from ZnAl-NADS, respectively. This slow release was attributed to strong electrostatic interactions between the drug and the anion exchanger. A modulated release is preferable to the action of the bulk NADS, showing increased effectiveness and minimizing the amount of the chemical available to pollute the soil and the water. The fitting data from modified Freundlich and parabolic diffusion models explain the release behavior of the NADS, suggesting that the drug released from ZnAl-NADS bionanohybrid was carried out from the interlamellar sites, according to the ion exchange diffusion process also involving intraparticle diffusion (coeffect). ZnAl-NADS was tested in vitro against Escherichia coli (Ec) and Pc and exhibited bacteriostatic and biocidal effects at 0.025 and 0.075 mg mL -1 , respectively. ZnAl-NADS was also tested in vivo as an ecological pesticide for combating potato soft rot and was found to delay typical disease symptoms. In conclusion, ZnAl-NADS can potentially be used to control pests, infestation, and plant disease.

A preliminary bioclimatic approach to predicting potential distribution of Phellinus noxious and geographical areas at risk from invasion

Treesearch

Ned B. Klopfenstein; Eric W. I. Pitman; John W. Hanna; Phil G. Cannon; Jane E. Stewart; Norio Sahashi; Yuko Ota; Tsutomu Hattori; Mitsuteru Akiba; Louise Shuey; Robert L. Schlub; Fred Brooks; Ndeme Atibalentja; Alvin M. C. Tang; Regent Y. C. Lam; Mike W. K. Leung; L. M. Chu; H. S. Kwan; Mohd Farid bin Ahmad; Su See Lee; Hsin-Han Lee; Jyh-Nong Tsai; Yu-Ching Huang; Chia-Lin Chung; Ruey-Fen Liou; Mee-Sook Kim

2016-01-01

Phellinus noxius, the cause of brown root-rot disease, is an invasive pathogen that was first described by Corner in Singapore (Corner 1932). It has a wide host range of primarily woody plants representing over 200 species from diverse families (Ann et al. 2002). This pathogen is also widespread, and has been reported to occur in many tropical/subtropical...

Metabolite analysis of endophytic fungi from cultivars of Zingiber officinale Rosc. identifies myriad of bioactive compounds including tyrosol.

PubMed

Anisha, C; Radhakrishnan, E K

2017-06-01

Endophytic fungi associated with rhizomes of four cultivars of Zingiber officinale were identified by molecular and morphological methods and evaluated for their activity against soft rot pathogen Pythium myriotylum and clinical pathogens. The volatile bioactive metabolites produced by these isolates were identified by GC-MS analysis of the fungal crude extracts. Understanding of the metabolites produced by endophytes is also important in the context of raw consumption of ginger as medicine and spice. A total of fifteen isolates were identified from the four varieties studied. The various genera identified were Acremonium sp., Gliocladiopsis sp., Fusarium sp., Colletotrichum sp., Aspergillus sp., Phlebia sp., Earliella sp., and Pseudolagarobasidium sp. The endophytic community was unique to each variety, which could be due to the varying host genotype. Fungi from phylum Basidiomycota were identified for the first time from ginger. Seven isolates showed activity against Pythium, while only two showed antibacterial activity. The bioactive metabolites identified in the fungal crude extracts include tyrosol, benzene acetic acid, ergone, dehydromevalonic lactone, N-aminopyrrolidine, and many bioactive fatty acids and their derivatives which included linoleic acid, oleic acid, myristic acid, n-hexadecanoic acid, palmitic acid methyl ester, and methyl linoleate. The presence of these varying bioactive endophytic fungi may be one of the reasons for the differences in the performance of the different ginger varieties.

Identification of pathogenicity-related genes in Fusarium oxysporum f. sp. cepae.

PubMed

Taylor, Andrew; Vágány, Viktória; Jackson, Alison C; Harrison, Richard J; Rainoni, Alessandro; Clarkson, John P

2016-09-01

Pathogenic isolates of Fusarium oxysporum, distinguished as formae speciales (f. spp.) on the basis of their host specificity, cause crown rots, root rots and vascular wilts on many important crops worldwide. Fusarium oxysporum f. sp. cepae (FOC) is particularly problematic to onion growers worldwide and is increasing in prevalence in the UK. We characterized 31 F. oxysporum isolates collected from UK onions using pathogenicity tests, sequencing of housekeeping genes and identification of effectors. In onion seedling and bulb tests, 21 isolates were pathogenic and 10 were non-pathogenic. The molecular characterization of these isolates, and 21 additional isolates comprising other f. spp. and different Fusarium species, was carried out by sequencing three housekeeping genes. A concatenated tree separated the F. oxysporum isolates into six clades, but did not distinguish between pathogenic and non-pathogenic isolates. Ten putative effectors were identified within FOC, including seven Secreted In Xylem (SIX) genes first reported in F. oxysporum f. sp. lycopersici. Two highly homologous proteins with signal peptides and RxLR motifs (CRX1/CRX2) and a gene with no previously characterized domains (C5) were also identified. The presence/absence of nine of these genes was strongly related to pathogenicity against onion and all were shown to be expressed in planta. Different SIX gene complements were identified in other f. spp., but none were identified in three other Fusarium species from onion. Although the FOC SIX genes had a high level of homology with other f. spp., there were clear differences in sequences which were unique to FOC, whereas CRX1 and C5 genes appear to be largely FOC specific. © 2015 The Authors Molecular Plant Pathology Published by British Society for Plant Pathology and John Wiley & Sons Ltd.

A novel plant ferredoxin-like protein and the regulator Hor are quorum-sensing targets in the plant pathogen Erwinia carotovora.

PubMed

Sjöblom, Solveig; Harjunpää, Heidi; Brader, Günter; Palva, E Tapio

2008-07-01

Quorum sensing (QS), a population-density-sensing mechanism, controls the production of the main virulence determinants, the plant cell-wall-degrading enzymes (PCWDEs) of the soft-rot phytopathogen Erwinia carotovora subsp. carotovora. In this study, we used random transposon mutagenesis with a gusA reporter construct to identify two new QS-controlled genes encoding the regulator Hor and a plant ferredoxin-like protein, FerE. The QS control of the identified genes was executed by the QS regulators ExpR1 and ExpR2 and mediated by the global repressor RsmA. Hor was shown to contribute to bacterial virulence at least partly through its control of PCWDE production. Our results showed that FerE contributes to oxidative stress tolerance and in planta fitness of the bacteria and suggest that QS could be central to control of oxidative stress tolerance. The presence of the FerE protein appears to be rather unique in heterotrophic bacteria and suggests an acquisition of the corresponding gene from plant host by horizontal gene transfer.

Potato plants genetically modified to produce N-acylhomoserine lactones increase susceptibility to soft rot erwiniae.

PubMed

Toth, I K; Newton, J A; Hyman, L J; Lees, A K; Daykin, M; Ortori, C; Williams, P; Fray, R G

2004-08-01

Many gram-negative bacteria employ N-acylhomoserine lactones (AHL) to regulate diverse physiological processes in concert with cell population density (quorum sensing [QS]). In the plant pathogen Erwinia carotovora, the AHL synthesized via the carI/expI genes are responsible for regulating the production of secreted plant cell wall-degrading exoenzymes and the antibiotic carbapen-3-em carboxylic acid. We have previously shown that targeting the product of an AHL synthase gene (yenI) from Yersinia enterocolitica to the chloroplasts of transgenic tobacco plants caused the synthesis in planta of the cognate AHL signaling molecules N-(3-oxohexanoyl)-L-homoserine lactone (3-oxo-C6-HSL) and N-hexanoylhomoserine lactone (C6-HSL), which in turn, were able to complement a carI-QS mutant. In the present study, we demonstrate that transgenic potato plants containing the yenI gene are also able to express AHL and that the presence and level of these AHL in the plant increases susceptibility to infection by E. carotovora. Susceptibility is further affected by both the bacterial level and the plant tissue under investigation.

Mechanisms of protection by NHA against fungal decay

Treesearch

Frederick Green; William Henry; Tor Schultz

2002-01-01

Treating wood with the water-borne sodium salt of N'-N-naphthaloylhydroxylamine (Na-NHA) protects wood against decay and termite damage. Initial testing indicated little or no inhibition of sapstain fungi, molds, or soft-rot fungi by Na-NHA, suggesting that the mechanism by which this compound protected wood was complex and not that of a broad-spectrum biocide....

Induction of Rhizopus oryzae germination under starvation using host metabolites increases spore susceptibility to heat stress

USDA-ARS?s Scientific Manuscript database

Sweet potato is a nutritional source worldwide. Soft rot caused by Rhizopus spp. is a major limiting factor in the storage of produce, rendering it potentially unsafe for human consumption. In this study, Rhizopus oryzae was used to develop a concept of postharvest disease control by weakening the p...

Bacterial associations with decaying wood : a review

Treesearch

C. A. Clausen

1996-01-01

Wood-inhabiting bacteria are associated with wood decay and may have an indirect influence on the decay process. Bacteria are able to affect wood permeability, attack wood structure, or work synergistically with other bacteria and soft-rot fungi to predispose wood to fungal attack. Bacteria that can inhabit chemically treated wood are recognized. The natural ability of...

Inhibition of decay fungi using cotton cellulose hydrolysis as a model for wood decay

Treesearch

Frederick Green

2000-01-01

Environmental pressures to replace chromium and arsenic in fixed waterborne preservatives have been increasing. Potential inhibitors of brown-, white- and soft-rot fungi need to be evaluated as alternative preservatives by screening and testing in, in vitro model systems. This paper reports the inhibition of cellulose depolymerization and weight loss of selected decay...

Derivation of Mutants of Erwinia carotovora subsp. betavasculorum Deficient in Export of Pectolytic Enzymes with Potential for Biological Control of Potato Soft Rot

PubMed Central

Costa, José M.; Loper, Joyce E.

1994-01-01

Erwinia carotovora subsp. betavasculorum Ecb168 produces an antibiotic(s) that suppresses growth of the related bacterium Erwinia carotovora subsp. carotovora in culture and in wounds of potato tubers. Strain Ecb168 also produces and secretes pectolytic enzymes and causes a vascular necrosis and root rot of sugar beet. Genes (out) involved in secretion of pectolytic enzymes by Ecb168 were localized to two HindIII fragments (8.5 and 10.5 kb) of Ecb168 genomic DNA by hybridization to the cloned out region of E. carotovora subsp. carotovora and by complementation of Out- mutants of E. carotovora subsp. carotovora. Out- mutants of Ecb168, which did not secrete pectate lyase into the culture medium, were obtained when deletions internal to either HindIII fragment were introduced into the genome of Ecb168 through marker exchange mutagenesis. Out- mutants of Ecb168 were complemented to the Out+ phenotype by introduction of the corresponding cloned HindIII fragment. Out- mutants of Ecb168 were less virulent than the Out+ parental strain on potato tubers. Strain Ecb168 and Out- derivatives inhibited the growth of E. carotovora subsp. carotovora in culture, indicating that the uncharacterized antibiotic(s) responsible for antagonism was exported through an out-independent mechanism. Strain Ecb168 and Out- derivatives reduced the establishment of large populations of E. carotovora subsp. carotovora in wounds of potato tubers and suppressed tuber soft rot caused by E. carotovora subsp. carotovora. PMID:16349316

Trehalose-related gene deletions in Fusarium verticillioides

USDA-ARS?s Scientific Manuscript database

Fusarium verticillioides is a widespread corn pathogen that causes root, stalk, and ear rot and produces fumonisins, toxic secondary metabolites associated with disease in livestock and humans. Our goal is to assess the feasibility of exploiting trehalose metabolism as a target for F. verticillioide...

Trehalose-related Gene Deletions in Fusarium verticillioides

USDA-ARS?s Scientific Manuscript database

Fusarium verticillioides is a widespread corn pathogen that causes root, stalk and ear rot and produces fumonisins, toxic secondary metabolites associated with disease in livestock and humans. Our goal is to assess the feasibility of exploiting trehalose metabolism as a target for F. verticillioides...

A new approach for strawberry disease control

USDA-ARS?s Scientific Manuscript database

Strawberry is grown around the world in different production systems and diverse environmental conditions, which creates challenges in controlling fruit-rot causing pathogens before and after harvest. Fungicides have been traditionally used to control these diseases, and in some areas, as many as 2...

The strange case of a biofilm-forming strain of Pichia fermentans, which controls Monilinia brown rot on apple but is pathogenic on peach fruit.

PubMed

Giobbe, Sara; Marceddu, Salvatore; Scherm, Barbara; Zara, Giacomo; Mazzarello, Vittorio L; Budroni, Marilena; Migheli, Quirico

2007-12-01

A biofilm-forming strain of Pichia fermentans proved to be most effective in controlling brown rot on apple fruit when coinoculated into artificial wounds with a phytopathogenic isolate of Monilinia fructicola. Culture filtrates and autoclaved cells had no significant influence on the disease. When sprayed onto the apple fruit surface, this yeast formed a thin biofilm but failed to colonize the underlying tissues. When inoculated into wounds artificially inflicted to peach fruit or when sprayed onto the surface of peach fruit, the same strain showed an unexpected pathogenic behaviour, causing rapid decay of fruit tissues even in the absence of M. fructicola. Both optical and scanning electron microscopy were used to evaluate the pattern of fruit tissue colonization by P. fermentans. While on apple surface and within the apple wound the antagonist retained its yeast-like shape, colonization of peach fruit tissue was always characterized by a transition from budding growth to pseudohyphal growth. These results suggest that pseudohyphal growth plays a major role in governing the potential pathogenicity of P. fermentans, further emphasizing the importance of a thorough risk assessment for the safe use of any novel biocontrol agent.

A Permutation-Randomization Approach to Test the Spatial Distribution of Plant Diseases.

PubMed

Lione, G; Gonthier, P

2016-01-01

The analysis of the spatial distribution of plant diseases requires the availability of trustworthy geostatistical methods. The mean distance tests (MDT) are here proposed as a series of permutation and randomization tests to assess the spatial distribution of plant diseases when the variable of phytopathological interest is categorical. A user-friendly software to perform the tests is provided. Estimates of power and type I error, obtained with Monte Carlo simulations, showed the reliability of the MDT (power > 0.80; type I error < 0.05). A biological validation on the spatial distribution of spores of two fungal pathogens causing root rot on conifers was successfully performed by verifying the consistency between the MDT responses and previously published data. An application of the MDT was carried out to analyze the relation between the plantation density and the distribution of the infection of Gnomoniopsis castanea, an emerging fungal pathogen causing nut rot on sweet chestnut. Trees carrying nuts infected by the pathogen were randomly distributed in areas with different plantation densities, suggesting that the distribution of G. castanea was not related to the plantation density. The MDT could be used to analyze the spatial distribution of plant diseases both in agricultural and natural ecosystems.

Evaluation of the biocontrol efficacy of a Serratia marcescens strain indigenous to tea rhizosphere for the management of root rot disease in tea

PubMed Central

Mangar, Preeti; Saha, Aniruddha

2018-01-01

The aim of the present study is to evaluate plant growth promoting and biocontrol efficacy of a Serratia marcescens strain ETR17 isolated from tea rhizosphere for the effective management of root rot disease in tea. Isolated bacterial culture ETR17 showed significant level of in vitro antagonism against nine different foliar and root pathogens of tea. The phenotypic and molecular characterization of ETR17 revealed the identity of the bacterium as Serratia marcescens. The bacterium was found to produce several hydrolytic enzymes like chitinase, protease, lipase, cellulase and plant growth promoting metabolites like IAA and siderophore. Scanning electron microscopic studies on the interaction zone between pathogen and antagonistic bacterial isolate revealed severe deformities in the fungal mycelia. Spectral analyses (LC-ESI-MS, UV-VIS spectrophotometry and HPLC) and TLC indicated the presence of the antibiotics pyrrolnitrin and prodigiosin in the extracellular bacterial culture extracts. Biofilm formation by ETR17 on polystyrene surface was also observed. In vivo application of talc-based formulations prepared with the isolate ETR17 in tea plantlets under green house conditions revealed effective reduction of root-rot disease as well as plant growth promotion to a considerable extent. Viability studies with the ETR17 talc formulation showed the survivability of the isolate up to six months at room temperature. The sustenance of ETR17 (concentration of 8-9x108 cfu g-1) in the soil after the application of talc formulation was recorded by ELISA. Safety studies revealed that ETR17 did not produce hemolysin as observed in pathogenic Serratia strains. The biocontrol strain reported in this study can be used for field application in order to minimize the use of chemical fungicides for disease control in tea gardens. PMID:29466418

Rhizospheric soil and root endogenous fungal diversity and composition in response to continuous Panax notoginseng cropping practices.

PubMed

Tan, Yong; Cui, Yinshan; Li, Haoyu; Kuang, Anxiu; Li, Xiaoran; Wei, Yunlin; Ji, Xiuling

2017-01-01

Rhizosphere and endophytic fungal communities are considered critically important for plant health and soil fertility. In response to continuous cropping, Panax notoginseng becomes vulnerable to attack by fungal pathogens. In the present study, culture-independent Illumina MiSeq was used to investigate the rhizospheric and root endophytic fungi in response to continuous Panax notoginseng cropping practices. The results demonstrated that fungal diversity is increased inside the roots and in rhizospheric. Ascomycota, Zygomycota, Basidiomycota and Chytridiomycota were the dominant phyla detected during the continuous cropping of Panax notoginseng. The fungal diversity in the rhizospheric soil and roots of root-rot P. notoginseng plants are less than that of healthy plants in the same cultivating year, thus showing that root-rot disease also affects the community structure and diversity of rhizospheric and root endophytic fungi. Similarities in the major fungal components show that endophytic fungal communities are similar to rhizospheric soil fungal community based on a specialized subset of organisms. Canonical correspondence analysis on the fungal communities in root-rot rhizospheric from both healthy plants and rotation soils reveals that the soil pH and organic matter have the greatest impact upon the microbial community composition during continuous cropping, whereas soil nutrition status does not significantly affect the fungal community composition in response to continuous cropping practices. In addition, the results suggest that the unclassified genera Leotiomycetes, Cylindrocarpon, Fusarium and Mycocentrospora are shown as the potential pathogens which are responsible for the obstacles in continuous cropping of P. notoginseng. Further exploration of these potential pathogens might be useful for the biological control of continuous cropping of P. notoginseng. Copyright © 2016 Elsevier GmbH. All rights reserved.

Evaluation of the biocontrol efficacy of a Serratia marcescens strain indigenous to tea rhizosphere for the management of root rot disease in tea.

PubMed

Dhar Purkayastha, Gargee; Mangar, Preeti; Saha, Aniruddha; Saha, Dipanwita

2018-01-01

The aim of the present study is to evaluate plant growth promoting and biocontrol efficacy of a Serratia marcescens strain ETR17 isolated from tea rhizosphere for the effective management of root rot disease in tea. Isolated bacterial culture ETR17 showed significant level of in vitro antagonism against nine different foliar and root pathogens of tea. The phenotypic and molecular characterization of ETR17 revealed the identity of the bacterium as Serratia marcescens. The bacterium was found to produce several hydrolytic enzymes like chitinase, protease, lipase, cellulase and plant growth promoting metabolites like IAA and siderophore. Scanning electron microscopic studies on the interaction zone between pathogen and antagonistic bacterial isolate revealed severe deformities in the fungal mycelia. Spectral analyses (LC-ESI-MS, UV-VIS spectrophotometry and HPLC) and TLC indicated the presence of the antibiotics pyrrolnitrin and prodigiosin in the extracellular bacterial culture extracts. Biofilm formation by ETR17 on polystyrene surface was also observed. In vivo application of talc-based formulations prepared with the isolate ETR17 in tea plantlets under green house conditions revealed effective reduction of root-rot disease as well as plant growth promotion to a considerable extent. Viability studies with the ETR17 talc formulation showed the survivability of the isolate up to six months at room temperature. The sustenance of ETR17 (concentration of 8-9x108 cfu g-1) in the soil after the application of talc formulation was recorded by ELISA. Safety studies revealed that ETR17 did not produce hemolysin as observed in pathogenic Serratia strains. The biocontrol strain reported in this study can be used for field application in order to minimize the use of chemical fungicides for disease control in tea gardens.

Expression of the β-1,3-glucanase gene bgn13.1 from Trichoderma harzianum in strawberry increases tolerance to crown rot diseases but interferes with plant growth.

PubMed

Mercado, José A; Barceló, Marta; Pliego, Clara; Rey, Manuel; Caballero, José L; Muñoz-Blanco, Juan; Ruano-Rosa, David; López-Herrera, Carlos; de Los Santos, Berta; Romero-Muñoz, Fernando; Pliego-Alfaro, Fernando

2015-12-01

The expression of antifungal genes from Trichoderma harzianum, mainly chitinases, has been used to confer plant resistance to fungal diseases. However, the biotechnological potential of glucanase genes from Trichoderma has been scarcely assessed. In this research, transgenic strawberry plants expressing the β-1,3-glucanase gene bgn13.1 from T. harzianum, under the control of the CaMV35S promoter, have been generated. After acclimatization, five out of 12 independent lines analysed showed a stunted phenotype when growing in the greenhouse. Moreover, most of the lines displayed a reduced yield due to both a reduction in the number of fruit per plant and a lower fruit size. Several transgenic lines showing higher glucanase activity in leaves than control plants were selected for pathogenicity tests. When inoculated with Colletotrichum acutatum, one of the most important strawberry pathogens, transgenic lines showed lower anthracnose symptoms in leaf and crown than control. In the three lines selected, the percentage of plants showing anthracnose symptoms in crown decreased from 61 % to a mean value of 16.5 %, in control and transgenic lines, respectively. Some transgenic lines also showed an enhanced resistance to Rosellinia necatrix, a soil-borne pathogen causing root and crown rot in strawberry. These results indicate that bgn13.1 from T. harzianum can be used to increase strawberry tolerance to crown rot diseases, although its constitutive expression affects plant growth and fruit yield. Alternative strategies such as the use of tissue specific promoters might avoid the negative effects of bgn13.1 expression in plant performance.

Stand-structural effects on Heterobasidion abietinum-related mortality following drought events in Abies pinsapo.

PubMed

Linares, Juan Carlos; Camarero, Jesús Julio; Bowker, Matthew A; Ochoa, Victoria; Carreira, José Antonio

2010-12-01

Climate change may affect tree-pathogen interactions. This possibility has important implications for drought-prone forests, where stand dynamics and disease pathogenicity are especially sensitive to climatic stress. In addition, stand structural attributes including density-dependent tree-to-tree competition may modulate the stands' resistance to drought events and pathogen outbreaks. To assess the effects of stand structure on root-rot-related mortality after severe droughts, we focused on Heterobasidion abietinum mortality in relict Spanish stands of Abies pinsapo, a drought-sensitive fir. We compared stand attributes and tree spatial patterns in three plots with H. abietinum root-rot disease and three plots without root-rot. Point-pattern analyses were used to investigate the scale and extent of mortality patterns and to test hypotheses related to the spread of the disease. Dendrochronology was used to date the year of death and to assess the association between droughts and growth decline. We applied a structural equation modelling approach to test if tree mortality occurs more rapidly than predicted by a simple distance model when trees are subjected to high tree-to-tree competition and following drought events. Contrary to expectations of drought mortality, the effect of precipitation on the year of death was strong and negative, indicating that a period of high precipitation induced an earlier tree death. Competition intensity, related to the size and density of neighbour trees, also induced an earlier tree death. The effect of distance to the disease focus was negligible except in combination with intensive competition. Our results indicate that infected trees have decreased ability to withstand drought stress, and demonstrate that tree-to-tree competition and fungal infection act as predisposing factors of forest decline and mortality.

Fungal endophytes of turmeric (Curcuma longa L.) and their biocontrol potential against pathogens Pythium aphanidermatum and Rhizoctonia solani.

PubMed

Vinayarani, G; Prakash, H S

2018-03-14

Endophytic fungi have been isolated from the healthy turmeric (Curcuma longa L.) rhizomes from South India. Thirty-one endophytes were identified based on morphological and ITS-rDNA sequence analysis. The isolated endophytes were screened for antagonistic activity against Pythium aphanidermatum (Edson) Fitzp., and Rhizoctonia solani Kuhn., causing rhizome rot and leaf blight diseases in turmeric respectively. Results revealed that only six endophytes showed > 70% suppression of test pathogens in antagonistic dual culture assays. The endophyte T. harzianum TharDOB-31 showed significant in vitro mycelial growth inhibition of P. aphanidermatum (76.0%) and R. solani (76.9%) when tested by dual culture method. The SEM studies of interaction zone showed morphological abnormalities like parasitism, shriveling, breakage and lysis of hyphae of the pathogens by endophyte TharDOB-31. Selected endophytic isolates recorded multiple plant growth promoting traits in in vitro studies. The rhizome bacterization followed by soil application of endophyte TharDOB-31 showed lowest Percent Disease Incidence of rhizome rot and leaf blight, 13.8 and 11.6% respectively. The treatment of TharDOB-31 exhibited significant increase in plant height (85 cm) and fresh rhizome yield/plant (425 g) in comparison with untreated control under greenhouse condition. The confocal microscopy validates the colonization of the TharDOB-31 in turmeric rhizomes. The secondary metabolites in ethyl acetate extract of TharDOB-31 were found to contain higher number of antifungal compounds by high resolution liquid chromatograph mass spectrometer analysis. Thereby, endophyte T. harzianum isolate can be exploited as a potential biocontrol agent for suppressing rhizome rot and leaf blight diseases in turmeric.

A survey of pre-harvest ear rot diseases of maize and associated mycotoxins in south and central Zambia.

PubMed

Mukanga, Mweshi; Derera, John; Tongoona, Pangirayi; Laing, Mark D

2010-07-15

Maize ear rots reduce grain yield and quality with implication on food security and health. Some of the pathogenic fungi produce mycotoxins in maize grain posing a health risk to humans and livestock. Unfortunately, the levels of ear rot and mycotoxin infection in grain produced by subsistence farmers in sub-Saharan countries are not known. A survey was thus conducted to determine the prevalence of the ear rot problem and levels of mycotoxins in maize grain. A total of 114 farmsteads were randomly sampled from 11 districts in Lusaka and southern provinces in Zambia during 2006. Ten randomly picked cobs were examined per farmstead and the ear rot disease incidence and severity were estimated on site. This was followed by the standard seed health testing procedures for fungal isolation in the laboratory. Results indicated that the dominant ear rots were caused by Fusarium and Stenocarpella. Incidence of Fusarium verticillioides ranged from 2 to 21%, whereas that of Stenocarpella maydis reached 37% on ear rot diseased maize grain. In addition, 2-7% F. verticillioides, and 3-18% Aspergillus flavus, respectively, were recovered from seemingly healthy maize grain. The mean rank of fungal species, from highest to lowest, was F. verticillioides, S. maydis, A. flavus, Fusarium graminearum, Aspergillus niger, Penicillium spp., Botrydiplodia spp., and Cladosporium spp. The direct competitive ELISA-test indicated higher levels of fumonisins than aflatoxins in pre-harvest maize grain samples. The concentration of fumonisins from six districts, and aflatoxin from two districts, was 10-fold higher than 2 ppm and far higher than 2 ppb maximum daily intake recommended by the FAO/WHO. The study therefore suggested that subsistence farmers and consumers in this part of Zambia, and maybe also in similar environments in sub-Saharan Africa, might be exposed to dangerous levels of mycotoxins due to the high levels of ear rot infections in maize grain. 2010 Elsevier B.V. All rights reserved.

Identification of pathogenicity‐related genes in Fusarium oxysporum f. sp. cepae

PubMed Central

Vágány, Viktória; Jackson, Alison C.; Harrison, Richard J.; Rainoni, Alessandro; Clarkson, John P.

2016-01-01

Summary Pathogenic isolates of Fusarium oxysporum, distinguished as formae speciales (f. spp.) on the basis of their host specificity, cause crown rots, root rots and vascular wilts on many important crops worldwide. Fusarium oxysporum f. sp. cepae (FOC) is particularly problematic to onion growers worldwide and is increasing in prevalence in the UK. We characterized 31 F. oxysporum isolates collected from UK onions using pathogenicity tests, sequencing of housekeeping genes and identification of effectors. In onion seedling and bulb tests, 21 isolates were pathogenic and 10 were non‐pathogenic. The molecular characterization of these isolates, and 21 additional isolates comprising other f. spp. and different Fusarium species, was carried out by sequencing three housekeeping genes. A concatenated tree separated the F. oxysporum isolates into six clades, but did not distinguish between pathogenic and non‐pathogenic isolates. Ten putative effectors were identified within FOC, including seven Secreted In Xylem (SIX) genes first reported in F. oxysporum f. sp. lycopersici. Two highly homologous proteins with signal peptides and RxLR motifs (CRX1/CRX2) and a gene with no previously characterized domains (C5) were also identified. The presence/absence of nine of these genes was strongly related to pathogenicity against onion and all were shown to be expressed in planta. Different SIX gene complements were identified in other f. spp., but none were identified in three other Fusarium species from onion. Although the FOC SIX genes had a high level of homology with other f. spp., there were clear differences in sequences which were unique to FOC, whereas CRX1 and C5 genes appear to be largely FOC specific. PMID:26609905

Endophytic bacteria from Piper tuberculatum Jacq.: isolation, molecular characterization, and in vitro screening for the control of Fusarium solani f. sp piperis, the causal agent of root rot disease in black pepper (Piper nigrum L.).

PubMed

Nascimento, S B; Lima, A M; Borges, B N; de Souza, C R B

2015-07-06

Endophytic bacteria have been found to colonize internal tissues in many different plants, where they can have several beneficial effects, including defense against pathogens. In this study, we aimed to identify endophytic bacteria associated with roots of the tropical piperaceae Piper tuberculatum, which is known for its resistance to infection by Fusarium solani f. sp piperis, the causal agent of black pepper (Piper nigrum) root rot disease in the Amazon region. Based on 16S rRNA gene sequence analysis, we isolated endophytes belonging to 13 genera: Bacillus, Paenibacillus, Pseudomonas, Enterobacter, Rhizobium, Sinorhizobium, Agrobacterium, Ralstonia, Serratia, Cupriavidus, Mitsuaria, Pantoea, and Staphylococcus. The results showed that 56.52% of isolates were associated with the phylum Proteobacteria, which comprised α, β, and γ classes. Other bacteria were related to the phylum Firmicutes, including Bacillus, which was the most abundant genus among all isolates. Antagonistic assays revealed that Pt12 and Pt13 isolates, identified as Pseudomonas putida and Pseudomonas sp, respectively, were able to inhibit F. solani f. sp piperis growth in vitro. We describe, for the first time, the molecular identification of 23 endophytic bacteria from P. tuberculatum, among which two Pseudomonas species have the potential to control the pathogen responsible for root rot disease in black pepper in the Amazon region.

Identification of Pathogenic Fusarium spp. Causing Maize Ear Rot and Potential Mycotoxin Production in China

PubMed Central

Duan, Canxing; Qin, Zihui; Yang, Zhihuan; Li, Weixi; Sun, Suli; Zhu, Zhendong; Wang, Xiaoming

2016-01-01

Ear rot is a serious disease that affects maize yield and grain quality worldwide. The mycotoxins are often hazardous to humans and livestock. In samples collected in China between 2009 and 2014, Fusarium verticillioides and F. graminearum species complex were the dominant fungi causing ear rot. According to the TEF-1α gene sequence, F. graminearum species complex in China included three independent species: F. graminearum, F. meridionale, and F. boothii. The key gene FUM1 responsible for the biosynthesis of fumonisin was detected in all 82 F. verticillioides isolates. Among these, 57 isolates mainly produced fumonisin B1, ranging from 2.52 to 18,416.44 µg/g for each gram of dry hyphal weight, in vitro. Three different toxigenic chemotypes were detected among 78 F. graminearum species complex: 15-ADON, NIV and 15-ADON+NIV. Sixty and 16 isolates represented the 15-ADON and NIV chemotypes, respectively; two isolates carried both 15-ADON and NIV-producing segments. All the isolates carrying NIV-specific segment were F. meridionale. The in vitro production of 15-ADON, 3-ADON, DON, and ZEN varied from 5.43 to 81,539.49; 6.04 to 19,590.61; 13.35 to 19,795.33; and 1.77 to 430.24 µg/g of dry hyphal weight, respectively. Altogether, our present data demonstrate potential main mycotoxin production of dominant pathogenic Fusarium in China. PMID:27338476

Monilinia Species Causing Brown Rot of Peach in China

PubMed Central

Hu, Meng-Jun; Cox, Kerik D.; Schnabel, Guido; Luo, Chao-Xi

2011-01-01

In this study, 145 peaches and nectarines displaying typical brown rot symptoms were collected from multiple provinces in China. A subsample of 26 single-spore isolates were characterized phylogenetically and morphologically to ascertain species. Phylogenetic analysis of internal transcribed spacer (ITS) regions 1 and 2, glyceraldehyde-3-phosphate dehydrogenase (G3PDH), β-tubulin (TUB2) revealed the presence of three distinct Monilinia species. These species included Monilinia fructicola, Monilia mumecola, and a previously undescribed species designated Monilia yunnanensis sp. nov. While M. fructicola is a well-documented pathogen of Prunus persica in China, M. mumecola had primarily only been isolated from mume fruit in Japan. Koch's postulates for M. mumecola and M. yunnanensis were fulfilled confirming pathogenicity of the two species on peach. Phylogenetic analysis of ITS, G3PDH, and TUB2 sequences indicated that M. yunnanensis is most closely related to M. fructigena, a species widely prevalent in Europe. Interestingly, there were considerable differences in the exon/intron structure of the cytochrome b (Cyt b) gene between the two species. Morphological characteristics, including spore size, colony morphology, lesion growth rate, and sporulation, support the phylogenetic evidence suggesting the designation of M. yunnanensis as a new species. A new multiplex PCR method was developed to facilitate the detection of M. yunnanensis and differentiation of Monilinia spp. causing brown rot of peach in China. PMID:21980371

Characterization and Reclassification of Yeasts Used for Biological Control of Postharvest Diseases of Fruits and Vegetables

PubMed Central

McLaughlin, R. J.; Wilson, C. L.; Chalutz, E.; Kurtzman, C. P.; Fett, W. F.; Osman, S. F.

1990-01-01

In previous studies workers have shown that three yeast strains (strains US-7, 82, and 101) have biological control activity against various postharvest fungal pathogens of fruits and vegetables, including Penicillium rots of apples and citrus and Botrytis rot of apples. In these reports the researchers have described these strains as Debaryomyces hansenii (anamorph, Candida famata) or Candida sp. strains. In this study we performed additional physiological, DNA reassociation, and mannan characterization tests that clearly established a new taxonomic classification for these strains, Candida guilliermondii. We also propose amendment of the physiological test profile in the taxonomic description of C. guilliermondii. PMID:16348361

Studies in neotropical polypores. 11, Antrodia aurantia, a new species from the Dominican Republic, Greater Antilles

Treesearch

D. Jean Lodge; Leif Ryvarden; Omar Paino Perdomo-Sanchez

2001-01-01

Antrodia aurantia Lodge, Ryvarden & Perdomo-Sanchez is described as new. It has bright orange resupinate basidiomes that lack rhizomorphs and has pores that are deep, soft, large, and angular to sinuous; it is associated with a brown rot on Pinus occidentalis. A key to all American Antrodia and Diplomitoporus species is provided.

Wood decay by Chlorociboria aeruginascens (Nyl.) Kanouse (Helotiales, Leotiaceae) and associated basidiomycete fungi

Treesearch

Dana L. Richter; Jessie A. Glaeser

2015-01-01

Two isolates of Chlorociboria aeruginascens (Nyl.) Kanouse incubated axenically on aspen wood blocks resulted in 18% and 32% mass loss after 134 wks (2 yrs 8 mo). Aspen wood decayed by C. aeruginascens contained cavities in the S2 layer of the secondary cell wall, similar to Type I soft rot attack, as well as erosion troughs and...

Association of Neonectria macrodidyma with dry root rot of citrus in California

USDA-ARS?s Scientific Manuscript database

The fungal genus Cylindrocarpon (teleomorph: Neonectria Wolenw.) include ubiquitous soilborne pathogens that cause black foot disease on a wide range of hosts, including grapevine, strawberry, apple, and conifers. Hosts typically become infected through natural wounds on roots and other below ground...

Introduction to Oomycetes

USDA-ARS?s Scientific Manuscript database

The oomycetes, also known as “water molds”, are a group of several hundred organisms that include some of the most devastating plant pathogens. The diseases they cause include seedling blights, damping-off, root rots, foliar blights and downy mildews. Some notable diseases are the late blight of po...

Pathogen profile update: Fusarium oxysporum.

PubMed

Michielse, Caroline B; Rep, Martijn

2009-05-01

Kingdom Fungi; Phylum Ascomycota; Class Sordariomycetes; Order Hypocreales; Family Nectriaceae; genus Fusarium. Very broad at the species level. More than 120 different formae speciales have been identified based on specificity to host species belonging to a wide range of plant families. Initial symptoms of vascular wilt include vein clearing and leaf epinasty, followed by stunting, yellowing of the lower leaves, progressive wilting, defoliation and, finally, death of the plant. On fungal colonization, the vascular tissue turns brown, which is clearly visible in cross-sections of the stem. Some formae speciales are not primarily vascular pathogens, but cause foot and root rot or bulb rot. Can cause severe losses in many vegetables and flowers, field crops, such as cotton, and plantation crops, such as banana, date palm and oil palm. Use of resistant varieties is the only practical measure for controlling the disease in the field. In glasshouses, soil sterilization can be performed. http://www.broad.mit.edu/annotation/genome/fusarium_group/MultiHome.html; http://www.fgsc.net/Fusarium/fushome.htm; http://www.phi-base.org/query.php

New Type of Antimicrobial Protein Produced by the Plant Pathogen Clavibacter michiganensis subsp. michiganensis

PubMed Central

Liu, Zhanliang; Ma, Ping; Holtsmark, Ingrid; Skaugen, Morten; Eijsink, Vincent G. H.

2013-01-01

It has previously been shown that the tomato pathogen Clavibacter michiganensis subsp. michiganensis secretes a 14-kDa protein, C. michiganensis subsp. michiganensis AMP-I (CmmAMP-I), that inhibits growth of Clavibacter michiganensis subsp. sepedonicus, the causal agent of bacterial ring rot of potato. Using sequences obtained from tryptic fragments, we have identified the gene encoding CmmAMP-I and we have recombinantly produced the protein with an N-terminal intein tag. The gene sequence showed that CmmAMP-I contains a typical N-terminal signal peptide for Sec-dependent secretion. The recombinant protein was highly active, with 50% growth inhibition (IC50) of approximately 10 pmol, but was not toxic to potato leaves or tubers. CmmAMP-I does not resemble any known protein and thus represents a completely new type of bacteriocin. Due to its high antimicrobial activity and its very narrow inhibitory spectrum, CmmAMP-1 may be of interest in combating potato ring rot disease. PMID:23851100

Patterns of lignin degradation and oxidative enzyme secretion by different wood- and litter-colonizing basidiomycetes and ascomycetes grown on beech-wood.

PubMed

Liers, Christiane; Arnstadt, Tobias; Ullrich, René; Hofrichter, Martin

2011-10-01

The degradation of lignocellulose and the secretion of extracellular oxidoreductases were investigated in beech-wood (Fagus sylvatica) microcosms using 11 representative fungi of four different ecophysiological and taxonomic groups causing: (1) classic white rot of wood (e.g. Phlebia radiata), (2) 'nonspecific' wood rot (e.g. Agrocybe aegerita), (3) white rot of leaf litter (Stropharia rugosoannulata) or (4) soft rot of wood (e.g. Xylaria polymorpha). All strong white rotters produced manganese-oxidizing peroxidases as the key enzymes of ligninolysis (75-2200 mU g(-1)), whereas lignin peroxidase activity was not detectable in the wood extracts. Interestingly, activities of two recently discovered peroxidases - aromatic peroxygenase and a manganese-independent peroxidase of the DyP-type - were detected in the culture extracts of A. aegerita (up to 125 mU g(-1)) and Auricularia auricula-judae (up to 400 mU g(-1)), respectively. The activity of classic peroxidases correlated to some extent with the removal of wood components (e.g. Klason lignin) and the release of small water-soluble fragments (0.5-1.0 kDa) characterized by aromatic constituents. In contrast, laccase activity correlated with the formation of high-molecular mass fragments (30-200 kDa). The differences observed in the degradation patterns allow to distinguish the rot types caused by basidiomycetes and ascomycetes and may be suitable for following the effects of oxidative key enzymes (ligninolytic peroxidases vs. laccases, role of novel peroxidases) during wood decay. © 2011 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

Theoretical studies on leaky-SAW properties influenced by layers on anisotropic piezoelectric crystals.

PubMed

Wallner, P; Ruile, W; Weigel, R

2000-01-01

Theoretical studies on the behavior of leaky-SAW (LSAW) properties in layered structures were performed. For these calculations rotYX LiTaO (3) and rotYX LiNbO(3) LSAW crystal cuts were used, assuming different layer materials. For LSAWs both the velocity and the inherent loss due to bulk wave emission into the substrate are strongly influenced by distinct layer parameters. As a result, these layer properties like elastic constants or thickness have shown a strong influence on the crystal cut angle of minimum LSAW loss. Moreover, for soft and stiff layer materials, a different shift of the LSAW loss minimum can occur. Therefore, using double-layer structures, the shift of the LSAW loss minimum can be influenced by appropriate chosen layers and ratios.

Development and Evaluation of Glycine max Germplasm Lines with Quantitative Resistance to Sclerotinia sclerotiorum

PubMed Central

McCaghey, Megan; Willbur, Jaime; Ranjan, Ashish; Grau, Craig R.; Chapman, Scott; Diers, Brian; Groves, Carol; Kabbage, Mehdi; Smith, Damon L.

2017-01-01

Sclerotinia sclerotiorum, the causal agent of Sclerotinia stem rot, is a devastating fungal pathogen of soybean that can cause significant yield losses to growers when environmental conditions are favorable for the disease. The development of resistant varieties has proven difficult. However, poor resistance in commercial cultivars can be improved through additional breeding efforts and understanding the genetic basis of resistance. The objective of this project was to develop soybean germplasm lines that have a high level of Sclerotinia stem rot resistance to be used directly as cultivars or in breeding programs as a source of improved Sclerotinia stem rot resistance. Sclerotinia stem rot-resistant soybean germplasm was developed by crossing two sources of resistance, W04-1002 and AxN-1-55, with lines exhibiting resistance to Heterodera glycines and Cadophora gregata in addition to favorable agronomic traits. Following greenhouse evaluations of 1,076 inbred lines derived from these crosses, 31 lines were evaluated for resistance in field tests during the 2014 field season. Subsequently, 11 Sclerotinia stem rot resistant breeding lines were moved forward for field evaluation in 2015, and seven elite breeding lines were selected and evaluated in the 2016 field season. To better understand resistance mechanisms, a marker analysis was conducted to identify quantitative trait loci linked to resistance. Thirteen markers associated with Sclerotinia stem rot resistance were identified on chromosomes 15, 16, 17, 18, and 19. Our markers confirm previously reported chromosomal regions associated with Sclerotinia stem rot resistance as well as a novel region of chromosome 16. The seven elite germplasm lines were also re-evaluated within a greenhouse setting using a cut petiole technique with multiple S. sclerotiorum isolates to test the durability of physiological resistance of the lines in a controlled environment. This work presents a novel and comprehensive classical breeding method for selecting lines with physiological resistance to Sclerotinia stem rot and a range of agronomic traits. In these studies, we identify four germplasm lines; 91–38, 51–23, SSR51–70, and 52–82B exhibiting a high level of Sclerotinia stem rot resistance combined with desirable agronomic traits, including high protein and oil contents. The germplasm identified in this study will serve as a valuable source of physiological resistance to Sclerotinia stem rot that could be improved through further breeding to generate high-yielding commercial soybean cultivars. PMID:28912790

Draft Genome Sequences of New Genomospecies "Candidatus Pectobacterium maceratum" Strains, Which Cause Soft Rot in Plants.

PubMed

Shirshikov, Fedor V; Korzhenkov, Aleksei A; Miroshnikov, Kirill K; Kabanova, Anastasia P; Barannik, Alla P; Ignatov, Alexander N; Miroshnikov, Konstantin A

2018-04-12

Investigation of collections of phytopathogenic bacteria has revealed some strains distinct from known Pectobacterium spp. We report here the draft genome sequences of five such strains, isolated during the period of 1947 to 2012. Based on comparative genomics, we propose a new candidate genomospecies of the genus Pectobacterium , " Candidatus Pectobacterium maceratum." Copyright © 2018 Shirshikov et al.

Draft Genome Sequences of New Genomospecies “Candidatus Pectobacterium maceratum” Strains, Which Cause Soft Rot in Plants

PubMed Central

2018-01-01

ABSTRACT Investigation of collections of phytopathogenic bacteria has revealed some strains distinct from known Pectobacterium spp. We report here the draft genome sequences of five such strains, isolated during the period of 1947 to 2012. Based on comparative genomics, we propose a new candidate genomospecies of the genus Pectobacterium, “Candidatus Pectobacterium maceratum.” PMID:29650577

Targhee Russet: A high yielding dual purpose, long russet potato cultivar having higher protein and vitamin C content and resistance to tuber soft rot

USDA-ARS?s Scientific Manuscript database

Targhee Russet is a dark-skinned russet potato variety with tubers slightly longer than Russet Burbank. It produces higher total and marketable yields than does Russet Burbank at most of the sites it was tested in the western United States. Tuber dormancy is about 58 days shorter than Russet Burba...

Host range and genetic relatedness of Colletotrichum acutatum isolates from fruit crops and leatherleaf fern in Florida.

PubMed

MacKenzie, S J; Peres, N A; Barquero, M P; Arauz, L F; Timmer, L W

2009-05-01

Isolates of Colletotrichum acutatum were collected from anthracnose-affected strawberry, leatherleaf fern, and Key lime; ripe-rot-affected blueberry; and postbloom fruit drop (PFD)-affected sweet orange in Florida. Additional isolates from ripe-rot-affected blueberry were collected from Georgia and North Carolina and from anthracnose-affected leatherleaf fern in Costa Rica. Pathogenicity tests on blueberry and strawberry fruit; foliage of Key lime, leatherleaf fern, and strawberry; and citrus flowers showed that isolates were highly pathogenic to their host of origin. Isolates were not pathogenic on foliage of heterologous hosts; however, several nonhomologous isolates were mildly or moderately pathogenic to citrus flowers and blueberry isolates were pathogenic to strawberry fruit. Based on sequence data from the internal transcribed spacer (ITS)1-5.8S rRNA-ITS2 region of the rDNA repeat, the glutaraldehyde-3-phosphate dehydrogenase intron 2 (G3PD), and the glutamine synthase intron 2 (GS), isolates from the same host were identical or very similar to each other and distinct from those isolated from other hosts. Isolates from leatherleaf fern in Florida were the only exception. Among these isolates, there were two distinct G3PD and GS sequences that occurred in three of four possible combinations. Only one of these combinations occurred in Costa Rica. Although maximum parsimony trees constructed from genomic regions individually displayed little or no homoplasy, there was a lack of concordance among genealogies that was consistent with a history of recombination. This lack of concordance was particularly evident within a clade containing PFD, Key lime, and leatherleaf fern isolates. Overall, the data indicated that it is unlikely that a pathogenic strain from one of the hosts examined would move to another of these hosts and produce an epidemic.

Effects of elevated CO2 on maize defense against mycotoxigenic Fusarium verticillioides

USDA-ARS?s Scientific Manuscript database

Elevated atmospheric carbon dioxide concentration ([CO2]) increased maize susceptibility to Fusarium verticillioides stalk rot. Even though the pathogen biomass accumulated to significantly higher levels at double ambient [CO2] (2x[CO2]), the projected [CO2] concentration to occur at the end of this...

Apple anthracnose canker life cycle and disease cycle

USDA-ARS?s Scientific Manuscript database

Apple anthracnose [caused by Neofabraea malicorticis (H.S. Jacks) anamorph Cryptosporiopsis curvispora (Peck)] is a fungal disease that impacts apple production. The pathogen produces cankers on trees as well as a rot on the fruit known as ‘Bull’s-eye rot’. The cankers cause severe damage to trees...

Working with anaerobic soil disinfestation for control of key soil-borne pathogens

USDA-ARS?s Scientific Manuscript database

Anaerobic soil disinfestation (ASD) has been shown to be effective in reducing Verticillium dahliae in soil and to be able to provide marketable fruit yields compatible to fumigation in California strawberry systems. However the effect of ASD on charcoal rot caused by Macrophomina phaseolina in Cali...

Aphanomyces root rot of alfalfa: Widespread distribution of race 2 in Minnesota

USDA-ARS?s Scientific Manuscript database

Strong seedling establishment in alfalfa is important to achieve the plant density needed to out-compete weeds and produce high biomass yields. Establishing alfalfa can be challenging because alfalfa seeds and seedlings are vulnerable to several pathogens present in soil. Wet soil conditions favor t...

Colonization of Clonostachys rosea on soybean root inoculated with Fusarium graminearum

USDA-ARS?s Scientific Manuscript database

Soybean root rot, caused by Fusarium graminearum, is a devastating disease. Clonostachys rosea has been reported to have protection against plant pathogens in different crops. The objectives of this study were to determine if a strain of C. rosea (ACM941) can colonize soybean root that were inocula...

Anaerobic soil disinfestation reduces survival and infectivity of Phytophthora nicotianae chlamydospores in pepper

USDA-ARS?s Scientific Manuscript database

Phytophthora nicotianae is the principal causal agent of root and crown rot disease of pepper plants in Extremadura (western Spain), a spring-summer crop in this region. Preplant soil treatment by anaerobic soil disinfestation (ASD) may effectively control plant pathogens in many crop production sys...

Status of Macrophomina phaseolina on strawberry in California and preliminary characterization of the pathogen

USDA-ARS?s Scientific Manuscript database

Macrophomina crown and root rot has become a significant soilborne disease issue in California. For many locations in the state, the disease is associated with fields that are no longer pre-plant, flat field fumigated with methyl bromide + chloropicrin. Inoculation experiments indicated that some di...

What lies beneath, unraveling the mysteries of Rhizoctonia and Pythium

USDA-ARS?s Scientific Manuscript database

Washington wheat and barley growers have long recognized that the soil-borne fungal pathogens Rhizoctonia and Pythium cause root rot, stunting and poor emergence and can chip away at yield, resulting in annual losses of 10 percent or more. Since several of these Rhizoctonia and Pythium species attac...

Complete genome sequence of a Klebsiella pneumoniae strain isolated from a known cotton insect boll vector

USDA-ARS?s Scientific Manuscript database

Klebsiella pneumoniae (associated with bacterial pneumonia) was previously isolated from Nezara viridula, a significant vector of cotton boll-rot pathogens. We provide the first annotated genome sequence of the cotton opportunistic strain K. pneumoniae 5-1. This data provides guidance to study the...

Induced resistance in tomato fruit by γ-aminobutyric acid for the control of alternaria rot caused by Alternaria alternata.

PubMed

Yang, Jiali; Sun, Cui; Zhang, Yangyang; Fu, Da; Zheng, Xiaodong; Yu, Ting

2017-04-15

The study investigated the effect of γ-aminobutyric acid (GABA) on the control of alternaria rot in tomato fruit and the possible mechanism involved. Our results showed exogenous GABA could stimulate remarkable resistance to the alternaria rot, while it had no direct antifungal activity against Alternaria alternata. Moreover, the activities of antioxidant enzymes, including peroxidase, superoxide dismutase and catalase, along with the expression of these corresponding genes, were significantly induced in the GABA treatment. The obtained data suggested GABA induced resistance against the necrotrophic pathogen A. alternata, at least in part by activating antioxidant enzymes, restricting the levels of cell death caused by reactive oxygen species. Meanwhile, the key enzyme genes of GABA shunt, GABA transaminase and succinic-semialdehyde dehydrogenase, were found up-regulated in the GABA treatment. The activation of the GABA shunt might play a vital role in the resistance mechanism underpinning GABA-induced plant immunity. Copyright © 2016 Elsevier Ltd. All rights reserved.

Insecticidal Bacillus thuringiensis Silences Erwinia carotovora Virulence by a New Form of Microbial Antagonism, Signal Interference

PubMed Central

Dong, Yi-Hu; Zhang, Xi-Fen; Xu, Jin-Ling; Zhang, Lian-Hui

2004-01-01

It is commonly known that bacteria may produce antibiotics to interfere with the normal biological functions of their competitors in order to gain competitive advantages. Here we report that Bacillus thuringiensis suppressed the quorum-sensing-dependent virulence of plant pathogen Erwinia carotovora through a new form of microbial antagonism, signal interference. E. carotovora produces and responds to acyl-homoserine lactone (AHL) quorum-sensing signals to regulate antibiotic production and expression of virulence genes, whereas B. thuringiensis strains possess AHL-lactonase, which is a potent AHL-degrading enzyme. B. thuringiensis did not seem to interfere with the normal growth of E. carotovora; rather, it abolished the accumulation of AHL signal when they were cocultured. In planta, B. thuringiensis significantly decreased the incidence of E. carotovora infection and symptom development of potato soft rot caused by the pathogen. The biocontrol efficiency is correlated with the ability of bacterial strains to produce AHL-lactonase. While all the seven AHL-lactonase-producing B. thuringiensis strains provided significant protection against E. carotovora infection, Bacillus fusiformis and Escherichia coli strains that do not process AHL-degradation enzyme showed little effect in biocontrol. Mutation of aiiA, the gene encoding AHL-lactonase in B. thuringiensis, resulted in a substantial decrease in biocontrol efficacy. These results suggest that signal interference mechanisms existing in natural ecosystems could be explored as a new version of antagonism for prevention of bacterial infections. PMID:14766576

Complete structural characterization of the lipid A fraction of a clinical strain of B. cepacia genomovar I lipopolysaccharide.

PubMed

Silipo, Alba; Molinaro, Antonio; Cescutti, Paola; Bedini, Emiliano; Rizzo, Roberto; Parrilli, Michelangelo; Lanzetta, Rosa

2005-05-01

Burkholderia cepacia, a Gram-negative bacterium ubiquitous in the environment, is a plant pathogen causing soft rot of onions. This microorganism has recently emerged as a life-threatening multiresistant pathogen in cystic fibrosis patients. An important virulence factor of B. cepacia is the lipopolysaccharide (LPS) fraction. Clinical isolates and environmental strains possess LPS of high inflammatory nature, which induces a high level production of cytokines. For the first time, the complete structure of the lipid A components isolated from the lipopolysaccharide fraction of a clinical strain of B. cepacia is described. The structural studies carried out by selective chemical degradations, MS, and NMR spectroscopy revealed multiple species differing in the acylation and in the phosphorylation patterns. The highest mass species was identified as a penta-acylated tetrasaccharide backbone containing two phosphoryl-arabinosamine residues in addition to the archetypal glucosamine disaccharide [Arap4N-l-beta-1-P-4-beta-D-GlcpN-(1-6)-alpha-D-GlcpN-1-P-1-beta-L-Arap4N]. Lipid A fatty acids substitution was also deduced, with two 3-hydroxytetradecanoic acids 14:0 (3-OH) in ester linkage, and two 3-hydroxyhexadecanoic acids 16:0 (3-OH) in amide linkage, one of which was substituted by a secondary 14:0 residue at its C-3. Other lipid A species present in the mixture and exhibiting lower molecular weight lacked one or both beta-L-Arap4N residues.

[Toxicity of Pythium oligandrum broth to animal and its control effect on rot diseases caused by Penicillium italicum and Penicillium digitatum in orange fruit storage].

PubMed

Tan, Yan; Peng, Liangzhi; Yuan, Ling; Wang, Shaobo

2015-11-04

In order to develop a safe, nontoxic and efficient biological antistaling agent and to decrease the incidence of rot diseases caused by the Penicillium italicum and Penicillium digitatum in orange fruit storage. the present experiment was carried out with Pythium oligandrum broth (POB) produced by our self-isolated strain (P. oligandrum CQ2010) to study the toxicity to animal. Thereafter, mycelium growth and spore germination of both P. digitatum and P. italicum and control effect of rot disease in orange storage were compared after treated by liquid culture medium (control), POB, prochloraz (PC) , and PC + POB. Gastric lavage with large amount POB did not influence mouse weight. The animals also showed no abnormality in appearance, behaviors and pathology changes in heart, liver, kidney, lung and intestine. POB decreased the hyphal growth by 70.24% - 93.74% and spore germination by 44.91% - 87.82% (24 h after POB addition) of these two pathogenic fungi. Disease incidence of orange fruit following P. italicum inoculation changed in the sequence: CK > POB > PC > PC + POB and the control efficacy behaved otherwise. In commercial simulation storage, the disease incidence of orange fruit caused by P. digitatum and P. italicum was above 50% of the total. The fruit rot rate was 26.40% (CK), 15.03% (POB), 16.61% (PC) and 4.21% (PC + POB). There were no significant differences in fruit quality under different treatments. POB was safe to animal and could decrease rot disease incidence caused by P. italicum and P. digitatum in orange storage whereby producing a positive interaction with prochloraz and controlling rot diseases caused by these two fungi.

Pseudomonas cichorii as the causal agent of midrib rot, an emerging disease of greenhouse-grown butterhead lettuce in Flanders.

PubMed

Cottyn, Bart; Heylen, Kim; Heyrman, Jeroen; Vanhouteghem, Katrien; Pauwelyn, Ellen; Bleyaert, Peter; Van Vaerenbergh, Johan; Höfte, Monica; De Vos, Paul; Maes, Martine

2009-05-01

Bacterial midrib rot of greenhouse-grown butterhead lettuce (Lactuca sativa L. var. capitata) is an emerging disease in Flanders (Belgium) and fluorescent pseudomonads are suspected to play an important role in the disease. Isolations from infected lettuces, collected from 14 commercial greenhouses in Flanders, yielded 149 isolates that were characterized polyphasically, which included morphological characteristics, pigmentation, pathogenicity tests by both injection and spraying of lettuce, LOPAT characteristics, FAME analysis, BOX-PCR fingerprinting, 16S rRNA and rpoB gene sequencing, as well as DNA-DNA hybridization. Ninety-eight isolates (66%) exhibited a fluorescent pigmentation and were associated with the genus Pseudomonas. Fifty-five of them induced an HR+ (hypersensitive reaction in tobacco leaves) response. The other 43 fluorescent isolates were most probably saprophytic bacteria and about half of them were able to cause rot on potato tuber slices. BOX-PCR genomic fingerprinting was used to assess the genetic diversity of the Pseudomonas midrib rot isolates. The delineated BOX-PCR patterns matched quite well with Pseudomonas morphotypes defined on the basis of colony appearance and variation in fluorescent pigmentation. 16S rRNA and rpoB gene sequence analyses allowed most of the fluorescent isolates to be allocated to Pseudomonas, and they belonged to either the Pseudomonas fluorescens group, Pseudomonas putida group, or the Pseudomonas cichorii/syringae group. In particular, the isolates allocated to this latter group constituted the vast majority of HR+ isolates and were identified as P. cichorii by DNA-DNA hybridization. They were demonstrated by spray-inoculation tests on greenhouse-grown lettuce to induce the midrib rot disease and could be re-isolated from lesions of inoculated plants. Four HR+ non-fluorescent isolates associated with one sample that showed an atypical midrib rot were identified as Dickeya sp.

Loop-mediated isothermal amplification (LAMP) based detection of Colletotrichum falcatum causing red rot in sugarcane.

PubMed

Chandra, Amaresh; Keizerweerd, Amber T; Que, Youxiong; Grisham, Michael P

2015-08-01

Red rot, caused by Colletotrichum falcatum, is a destructive disease prevalent in most sugarcane-producing countries. Disease-free sugarcane planting materials (setts) are essential as the pathogen spreads primarily through infected setts. The present study was undertaken to develop a loop-mediated isothermal amplification (LAMP) assay for the detection of C. falcatum. C. falcatum genomic DNA was isolated from pure mycelium culture and infected tissues. Four sets of primers corresponding to a unique DNA sequence specific to C. falcatum were designed. Specificity of the LAMP test was checked with DNA of another fungal pathogen of sugarcane, Puccinia melanocephala, as well as two closely-related species, Colletotrichum fructivorum and Colletotrichum acutatum. No reaction was found with the three pathogens. When C. falcatum DNA from pure culture was used in a detection limit analysis, sensitivity of the LAMP method was observed to be ten times higher than that of conventional PCR; however, sensitivity was only 5 times higher when DNA from C. falcatum-infected tissues was used. Using the LAMP assay, C. falcatum DNA is amplified with high specificity, efficiency, and rapidity under isothermal conditions. Moreover, visual judgment of color change in <1 h without further post-amplification processing makes the LAMP method convenient, economical, and useful in diagnostic laboratories and the field.

Comparative genome analysis of Basidiomycete fungi

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

Riley, Robert; Salamov, Asaf; Henrissat, Bernard

Fungi of the phylum Basidiomycota (basidiomycetes), make up some 37percent of the described fungi, and are important in forestry, agriculture, medicine, and bioenergy. This diverse phylum includes symbionts, pathogens, and saprotrophs including the majority of wood decaying and ectomycorrhizal species. To better understand the genetic diversity of this phylum we compared the genomes of 35 basidiomycetes including 6 newly sequenced genomes. These genomes span extremes of genome size, gene number, and repeat content. Analysis of core genes reveals that some 48percent of basidiomycete proteins are unique to the phylum with nearly half of those (22percent) found in only one organism.more » Correlations between lifestyle and certain gene families are evident. Phylogenetic patterns of plant biomass-degrading genes in Agaricomycotina suggest a continuum rather than a dichotomy between the white rot and brown rot modes of wood decay. Based on phylogenetically-informed PCA analysis of wood decay genes, we predict that that Botryobasidium botryosum and Jaapia argillacea have properties similar to white rot species, although neither has typical ligninolytic class II fungal peroxidases (PODs). This prediction is supported by growth assays in which both fungi exhibit wood decay with white rot-like characteristics. Based on this, we suggest that the white/brown rot dichotomy may be inadequate to describe the full range of wood decaying fungi. Analysis of the rate of discovery of proteins with no or few homologs suggests the value of continued sequencing of basidiomycete fungi.« less

Newly Isolated Bacteriophages from the Podoviridae, Siphoviridae, and Myoviridae Families Have Variable Effects on Putative Novel Dickeya spp.

PubMed

Alič, Špela; Naglič, Tina; Tušek-Žnidarič, Magda; Ravnikar, Maja; Rački, Nejc; Peterka, Matjaž; Dreo, Tanja

2017-01-01

Soft rot pathogenic bacteria from the genus Dickeya cause severe economic losses in orchid nurseries worldwide, and there is no effective control currently available. In the last decade, the genus Dickeya has undergone multiple changes as multiple new taxa have been described, and just recently a new putative Dickeya species was reported. This study reports the isolation of three bacteriophages active against putative novel Dickeya spp. isolates from commercially produced infected orchids that show variable host-range profiles. Bacteriophages were isolated through enrichment from Dickeya -infected orchid tissue. Convective interaction media monolith chromatography was used to isolate bacteriophages from wastewaters, demonstrating its suitability for the isolation of infective bacteriophages from natural sources. Based on bacteriophage morphology, all isolated bacteriophages were classified as being in the order Caudovirales , belonging to three different families, Podoviridae , Myoviridae , and Siphoviridae . The presence of three different groups of bacteriophages was confirmed by analyzing the bacteriophage specificity of bacterial hosts, restriction fragment length polymorphism and plaque morphology. Bacteriophage BF25/12, the first reported Podoviridae bacteriophage effective against Dickeya spp., was selected for further characterization. Its genome sequence determined by next-generation sequencing showed limited similarity to other characterized Podoviridae bacteriophages. Interactions among the bacteriophages and Dickeya spp. were examined using transmission electron microscopy, which revealed degradation of electron-dense granules in response to bacteriophage infection in some Dickeya strains. The temperature stability of the chosen Podoviridae bacteriophage monitored over 1 year showed a substantial decrease in the survival of bacteriophages stored at -20°C over longer periods. It showed susceptibility to low pH and UV radiation but was stable in neutral and alkaline pH. Furthermore, the stability of the tested bacteriophage was also connected to the incubation medium and bacteriophage concentration at certain pH values. Finally, the emergence of bacteriophage-resistant bacterial colonies is highly connected to the concentration of bacteriophages in the bacterial environment. This is the first report on bacteriophages against Dickeya from the Podoviridae family to expand on potential bacteriophages to include in bacteriophage cocktails as biocontrol agents. Some of these bacteriophage isolates also showed activity against Dickeya solani , an aggressive strain that causes the soft rot of potatoes, which indicates their broad potential as biocontrol agents.

Newly Isolated Bacteriophages from the Podoviridae, Siphoviridae, and Myoviridae Families Have Variable Effects on Putative Novel Dickeya spp.

PubMed Central

Alič, Špela; Naglič, Tina; Tušek-Žnidarič, Magda; Ravnikar, Maja; Rački, Nejc; Peterka, Matjaž; Dreo, Tanja

2017-01-01

Soft rot pathogenic bacteria from the genus Dickeya cause severe economic losses in orchid nurseries worldwide, and there is no effective control currently available. In the last decade, the genus Dickeya has undergone multiple changes as multiple new taxa have been described, and just recently a new putative Dickeya species was reported. This study reports the isolation of three bacteriophages active against putative novel Dickeya spp. isolates from commercially produced infected orchids that show variable host-range profiles. Bacteriophages were isolated through enrichment from Dickeya-infected orchid tissue. Convective interaction media monolith chromatography was used to isolate bacteriophages from wastewaters, demonstrating its suitability for the isolation of infective bacteriophages from natural sources. Based on bacteriophage morphology, all isolated bacteriophages were classified as being in the order Caudovirales, belonging to three different families, Podoviridae, Myoviridae, and Siphoviridae. The presence of three different groups of bacteriophages was confirmed by analyzing the bacteriophage specificity of bacterial hosts, restriction fragment length polymorphism and plaque morphology. Bacteriophage BF25/12, the first reported Podoviridae bacteriophage effective against Dickeya spp., was selected for further characterization. Its genome sequence determined by next-generation sequencing showed limited similarity to other characterized Podoviridae bacteriophages. Interactions among the bacteriophages and Dickeya spp. were examined using transmission electron microscopy, which revealed degradation of electron-dense granules in response to bacteriophage infection in some Dickeya strains. The temperature stability of the chosen Podoviridae bacteriophage monitored over 1 year showed a substantial decrease in the survival of bacteriophages stored at -20°C over longer periods. It showed susceptibility to low pH and UV radiation but was stable in neutral and alkaline pH. Furthermore, the stability of the tested bacteriophage was also connected to the incubation medium and bacteriophage concentration at certain pH values. Finally, the emergence of bacteriophage-resistant bacterial colonies is highly connected to the concentration of bacteriophages in the bacterial environment. This is the first report on bacteriophages against Dickeya from the Podoviridae family to expand on potential bacteriophages to include in bacteriophage cocktails as biocontrol agents. Some of these bacteriophage isolates also showed activity against Dickeya solani, an aggressive strain that causes the soft rot of potatoes, which indicates their broad potential as biocontrol agents. PMID:29033917

Fusarium proliferatum - Causal agent of garlic bulb rot in Spain: Genetic variability and mycotoxin production.

PubMed

Gálvez, Laura; Urbaniak, Monika; Waśkiewicz, Agnieszka; Stępień, Łukasz; Palmero, Daniel

2017-10-01

Fusarium proliferatum is a world-wide occurring fungal pathogen affecting several crops included garlic bulbs. In Spain, this is the most frequent pathogenic fungus associated with garlic rot during storage. Moreover, F. proliferatum is an important mycotoxigenic species, producing a broad range of toxins, which may pose a risk for food safety. The aim of this study is to assess the intraspecific variability of the garlic pathogen in Spain implied by analyses of translation elongation factor (tef-1α) and FUM1 gene sequences as well as the differences in growth rates. Phylogenetic characterization has been complemented with the characterization of mating type alleles as well as the species potential as a toxin producer. Phylogenetic trees based on the sequence of the translation elongation factor and FUM1 genes from seventy nine isolates from garlic revealed a considerable intraspecific variability as well as high level of diversity in growth speed. Based on the MAT alleles amplified by PCR, F. proliferatum isolates were separated into different groups on both trees. All isolates collected from garlic in Spain proved to be fumonisin B 1 , B 2 , and B 3 producers. Quantitative analyses of fumonisins, beauvericin and moniliformin (common secondary metabolites of F. proliferatum) showed no correlation with phylogenetic analysis neither mycelial growth. This pathogen presents a high intraspecific variability within the same geographical region and host, which is necessary to be considered in the management of the disease. Copyright © 2017 Elsevier Ltd. All rights reserved.

PecS and PecT coregulate the synthesis of HrpN and pectate lyases, two virulence determinants in Erwinia chrysanthemi 3937.

PubMed

Nasser, William; Reverchon, Sylvie; Vedel, Regine; Boccara, Martine

2005-11-01

Erwinia chrysanthemi strain 3937 is a necrotrophic bacterial plant pathogen. Pectinolytic enzymes and, in particular, pectate lyases play a key role in soft rot symptoms; however, the efficient colonization of plants by E. chrysanthemi requires additional factors. These factors include HrpN (harpin), a heat-stable, glycine-rich hydrophilic protein, which is secreted by the type III secretion system. We investigated the expression of hrpN in E. chrysanthemi 3937 in various environmental conditions and different regulatory backgrounds. Using lacZ fusions, hrpN expression was markedly influenced by the carbon source, osmolarity, growth phase, and growth substrate. hrpN was repressed when pectinolysis started and negatively regulated by the repressors of pectate lyase synthesis, PecS and PecT. Primer extension data and in vitro DNA-protein interaction experiments support a model whereby PecS represses hrpN expression by binding to the hrpN regulatory region and inhibiting transcript elongation. The results suggest coordinated regulation of HrpN and pectate lyases by PecS and PecT. A putative model of the synthesis of these two virulence factors in E. chrysanthemi during pathogenesis is presented.

Classification and Taxonomy of Vegetable Macergens

PubMed Central

Aremu, Bukola R.; Babalola, Olubukola O.

2015-01-01

Macergens are bacteria capable of releasing pectic enzymes (pectolytic bacteria). These enzymatic actions result in the separation of plant tissues leading to total plant destruction. This can be attributed to soft rot diseases in vegetables. These macergens primarily belong to the genus Erwinia and to a range of opportunistic pathogens namely: the Xanthomonas spp., Pseudomonas spp., Clostridium spp., Cytophaga spp., and Bacillus spp. They consist of taxa that displayed considerable heterogeneity and intermingled with members of other genera belonging to the Enterobacteriaceae. They have been classified based on phenotypic, chemotaxonomic and genotypic which obviously not necessary in the taxonomy of all bacterial genera for defining bacterial species and describing new ones These taxonomic markers have been used traditionally as a simple technique for identification of bacterial isolates. The most important fields of taxonomy are supposed to be based on clear, reliable and worldwide applicable criteria. Hence, this review clarifies the taxonomy of the macergens to the species level and revealed that their taxonomy is beyond complete. For discovery of additional species, further research with the use modern molecular methods like phylogenomics need to be done. This can precisely define classification of macergens resulting in occasional, but significant changes in previous taxonomic schemes of these macergens. PMID:26640465

Classification and Taxonomy of Vegetable Macergens.

PubMed

Aremu, Bukola R; Babalola, Olubukola O

2015-01-01

Macergens are bacteria capable of releasing pectic enzymes (pectolytic bacteria). These enzymatic actions result in the separation of plant tissues leading to total plant destruction. This can be attributed to soft rot diseases in vegetables. These macergens primarily belong to the genus Erwinia and to a range of opportunistic pathogens namely: the Xanthomonas spp., Pseudomonas spp., Clostridium spp., Cytophaga spp., and Bacillus spp. They consist of taxa that displayed considerable heterogeneity and intermingled with members of other genera belonging to the Enterobacteriaceae. They have been classified based on phenotypic, chemotaxonomic and genotypic which obviously not necessary in the taxonomy of all bacterial genera for defining bacterial species and describing new ones These taxonomic markers have been used traditionally as a simple technique for identification of bacterial isolates. The most important fields of taxonomy are supposed to be based on clear, reliable and worldwide applicable criteria. Hence, this review clarifies the taxonomy of the macergens to the species level and revealed that their taxonomy is beyond complete. For discovery of additional species, further research with the use modern molecular methods like phylogenomics need to be done. This can precisely define classification of macergens resulting in occasional, but significant changes in previous taxonomic schemes of these macergens.

Breeding for resistance in Norway spruce to the root and butt rot fungi Heterobasidion spp

Treesearch

G. Swedjemark; A.K. Borg-Karlson; B. Karlsson

2012-01-01

Results from previous studies of resistance in Norway spruce (Picea abies (L.) Karst.) to the pathogens Heterobasidion spp. show significant genotypic variation in fungal growth and spore susceptibility among Norway spruce clones. The genetic variation and the heritability are large enough for practical breeding purposes and...

Fungal pathogen complexes associated with rambutan, longan and mango diseases in Puerto Rico

USDA-ARS?s Scientific Manuscript database

Different fungi have been associated with diseased inflorescences, leaves, and fruits of mango, rambutan and longan. During a fungal disease survey conducted between 2008 and 2013 at six orchards of rambutan and longan, and one orchard of mango in Puerto Rico, symptoms such as fruit rot, infloresc...

Biology, diagnosis and management of Heterobasidion Root Disease of southern pines

Treesearch

Tyler J. Dreaden; Jason A.  Smith; Michelle M. Cram; David R   Coyle

2016-01-01

Heterobasidion root disease (previously called annosum, annosus, or Fomes root disease / root rot) is one of the most economically damaging forest diseases in the Northern Hemisphere. Heterobasidion root disease (HRD) in the southeastern U.S. is caused by the pathogen Heterobasidion irregulare, which infects loblolly, longleaf, pitch, shortleaf, slash, Virginia, and...

Climate change and crop phytochemical defenses: Potential implications for food security and food safety

USDA-ARS?s Scientific Manuscript database

Elevated atmospheric carbon dioxide concentration ([CO2]) increased maize susceptibility to Fusarium verticillioides stalk rot. Even though the pathogen biomass accumulated to significantly higher levels at double ambient [CO2] (2x[CO2]), the projected [CO2] concentration to occur at the end of this...

FUM and BIK gene expression contribute to describe fumonisin and bikaverin synthesis in Fusarium verticillioides

USDA-ARS?s Scientific Manuscript database

Fusarium verticillioides is a maize-pathogen that causes ear and stalk rot and produces toxic secondary metabolites including fumonisins and bikaverin. Fumonisins are known to cause disease in animals and humans; bikaverin is a pigment associated with self-defense. Water activity (aw) is one of the ...

Influence of weed species and time of glyphosate application on Rhizoctonia root rot of barley

USDA-ARS?s Scientific Manuscript database

Rhizoctonia solani AG-8 causes root disease in wheat, barley, canola and other small grains in the dryland inland Pacific Northwest. The pathogen survives between crops on roots of volunteers and grassy weeds. Destroying this green bridge with herbicides such as glyphosate is a common tactic to cont...

First report of root rot caused by Phytopythium helicoides on pistachio rootstock in California

USDA-ARS?s Scientific Manuscript database

We examined pathogenicity of Phytopythium helicoides on UCB-1 rootstock to investigate its role in root disease and collapse observed on potted pistachio plants. Approximately 25 potted 2-year-old pistachio rootstock trees in a Kern County, CA, research plot maintained outdoors and irrigated to cont...

Botrytis and native grape yeasts – not all interactions are created equal

USDA-ARS?s Scientific Manuscript database

Native yeasts are of increasing interest to grape growers and winemakers in Washington State because of their potential to contribute to vineyard health and wine quality. In this pilot project, we used eleven strains of native yeasts and nine isolates of the Botrytis bunch rot pathogen, all obtained...

Estimating the susceptibility to Phytophthora alni globally using both statistical analyses and expert knowledge

Treesearch

Marla C. Downing; Thomas Jung; Vernon Thomas; Markus Blaschke; Michael F. Tuffly; Robin Reich

2010-01-01

Phytophthora alni subspecies alni Brasier and S.A. Kirk is a recently hybridized soil and waterborne pathogen causing root and collar rot of species of the genus Alnus spp. (alder). It has quickly spread throughout Europe via planting of infested nursery stock and irrigating fields with infested river...

Genome-wide association mapping of resistance to a Brazilian isolate of Sclerotinia sclerotiorum in soybean genotypes mostly from Brazil

USDA-ARS?s Scientific Manuscript database

Sclerotinia Stem Rot (SSR), caused by the fungal pathogen Sclerotinia sclerotiorum, is ubiquitous in cooler climates where soybean crops are grown. Breeding for resistance to SSR remains challenging in crops like soybean, where no single gene provides strong resistance, but instead, multiple genes w...

Response of sweet sorghum lines to stalk pathogens fusarium thapsinum and macrophomina phaseolina

USDA-ARS?s Scientific Manuscript database

Sweet sorghum [Sorghum bicolor (L.) Moench] has potential for bioenergy. It is adapted to a variety of U.S. locations and the extracted juice can be directly fermented into ethanol. However, little research on fungal stalk rots has been reported, even though these diseases pose serious constraints f...

Response of sweet sorghum lines to stalk pathogens Fusarium thapsinum and Macrophomina phaseolina

USDA-ARS?s Scientific Manuscript database

Sweet sorghum (Sorghum bicolor (L.) Moench) has potential for bioenergy. It is adapted to a variety of U.S. locations and the extracted juice can be directly fermented into ethanol. However, little research on fungal stalk rots, diseases that pose serious constraints for yield and quality of juice a...

Characterization of Pythium spp. collected from corn and soybean soil in Illinois

USDA-ARS?s Scientific Manuscript database

Pythium root rot is widely distributed in major soybean (Glycine max) production areas throughout the world. There are many species of Pythium described on soybean and other crops, although not all species are pathogenic on all crops. The objectives of this study were to isolate, identify, and evalu...

First report of the root-rot pathogen, Armillaria nabsnona, from Hawaii

Treesearch

J. W. Hanna; N. B. Klopfenstein; M. -S. Kim

2007-01-01

The genus Armillaria (2) and Armillaria mellea sensu lato (3) have been reported previously from Hawaii. However, Armillaria species in Hawaii have not been previously identified by DNA sequences, compatibility tests, or other methods that distinguish currently recognized taxa. In August 2005, Armillaria rhizomorphs and mycelial bark fans were collected from two...

QTL meta-analysis provides a comprehensive view of loci controlling partial resistance to Aphanomyces euteiches in four sources of resistance in pea

USDA-ARS?s Scientific Manuscript database

More knowledge about diversity of Quantitative Trait Loci (QTL) controlling polygenic disease resistance in natural genetic variation of crop species is required for durably improving plant genetic resistances to pathogens. Polygenic partial resistance to Aphanomyces root rot, due to Aphanomcyces eu...

Differential gene expression during the pathogenic interaction between Pichia fermentans and peach fruit

USDA-ARS?s Scientific Manuscript database

A biofilm-forming strain of Pichia fermentans was found to be a very strong antagonist against brown rot and grey mold in artificially wounded apple fruit when co-inoculated with either Monilinia fructicola or Botrytis cinerea, respectively. The same strain of yeast; however, was an aggressive path...

Development and characterization of simple sequence repeats for Bipolaris sokiniana and cross transferability to related species

USDA-ARS?s Scientific Manuscript database

Simple sequence repeats (SSR) markers were developed from a small insert genomic library for Bipolaris sorokiniana, a mitosporic fungal pathogen that causes spot blotch and root rot in switchgrass. About 59% of sequenced clones (n=384) harbored various SSR motifs. After eliminating the redundant seq...

Effects of Silicon Amendment on Soilborne and Fruit Diseases of Avocado

PubMed Central

Dann, Elizabeth K.; Le, Duy P.

2017-01-01

The effects of silicon (Si) amendment have been studied in several plant/pathogen interactions; however, studies in horticultural tree crops are limited. Effects of amendment with soluble potassium silicate (AgSil®32, approximately 30% available Si), or milled cement building board by-products (Mineral Mulch (MM) or Mineral Dust (MD), containing 5% available Si) were investigated in field and greenhouse trials with avocado. Orchard soil drench applications with potassium silicate improved yield and quality of fruit, but visual health of trees declining from Phytophthora root rot (PRR) was not affected. Orchard spray or trunk injection applications with potassium silicate were ineffective. Amendment of potting mix with MM and MD reduced root necrosis of avocado seedlings after inoculation with Calonectria ilicicola, an aggressive soilborne pathogen causing black root rot. Application of MM to mature orchard trees declining with PRR had a beneficial effect on visual tree health, and Si accumulation in leaves and fruit peel, after only 10 months. Products that deliver available Si consistently for uptake are likely to be most successful in perennial tree crops. PMID:29053639

Analysis of the community compositions of rhizosphere fungi in soybeans continuous cropping fields.

PubMed

Bai, Li; Cui, Jiaqi; Jie, Weiguang; Cai, Baiyan

2015-11-01

We used rhizosphere soil sampled from one field during zero year and two years of continuous cropping of high-protein soybean to analyze the taxonomic community compositions of fungi during periods of high-incidence of root rot. Our objectives were to identify the dominant pathogens in order to provide a theoretical basis for the study of pathogenesis as well as control tactics for soybean root rot induced by continuous cropping. A total of 17,801 modified internal transcribed spacer (ITS) sequences were obtained from three different soybean rhizosphere soil samples after zero year and 1 or 2 years of continuous cropping using 454 high-throughput sequencing. The dominant eumycote fungal were identified to be Ascomycota and Basidiomycota in the three soil samples. Continuous cropping of soybean affected the diversity of fungi in rhizosphere soils and increased the abundance of Thelebolus and Mortierellales significantly. Thanatephorus, Fusarium, and Alternaria were identified to be the dominant pathogenic fungal genera in rhizosphere soil from continuously cropped soybean fields. Copyright © 2015 Elsevier GmbH. All rights reserved.

RAPD cluster analysis and chlorate sensitivity of some Indian isolates of Macrophomina phaseolina from sorghum and their relationships with pathogenicity.

PubMed

Das, I K; Fakrudin, B; Arora, D K

2008-01-01

Charcoal rot caused by Macrophomina phaseolina is an economically important disease in sorghum grown during the post rainy season in India. Variations in random amplified polymorphic DNA (RAPD) polymorphisms, chlorate sensitivity and pathogenicity were studied among sorghum isolates of M. phaseolina collected from different parts of India. RAPD data based on 14 random primers of Kit A and C (OPA and OPC) on 20 isolates showed a high degree of polymorphism (98.1%) in different isolates. UPGMA dendrogram on RAPD data produced 7 clusters at the level of 37% similarity. Isolates from the same locations showed a tendency to group closer, substantiating closer genetic relatedness. Sorghum infecting Macrophomina isolates showed a mixed response for sensitivity to potassium chlorate (120 mM). Chlorate-resistant isolates were predominant (>65% of the isolates) over sensitive isolates. Chlorate-sensitive isolates were found to be genetically closer among them than the resistant ones. For the first time it was shown that chlorate sensitivity in Macrophomina had some relations with charcoal rot severity in sorghum.

Effects of Drought-Stress on Fusarium Crown Rot Development in Barley

PubMed Central

Liu, Xinlun; Liu, Chunji

2016-01-01

Fusarium crown rot (FCR), caused by various Fusarium species, is a chronic disease of cereals in many semi-arid regions worldwide. To clarify what effects drought-stress may have on FCR development, visual assessment, histological analysis and quantitative PCR were used to analyse the infection process of F. pseudograminearum in barley. This study observed for the first time that the severity of FCR symptom reflects the quantity of pathogens in infected tissues of barley under both drought-stressed and well-watered conditions. Drought-stress prolongs the initial infection phase but enhances the proliferation and spread of Fusarium pathogens after the initial infection phase. Under drought-stressed conditions, the invading hyphae were frequently observed to re-emerge from stomata and invade again the surrounding epidermis cells. Under the well-watered conditions, however, very few hyphae re-emerged from stomata and most infection was caused by hyphae intracellularly grown. It was also observed that drought-stress increased the length and density of trichomes dramatically especially in the susceptible genotypes, and that the length and density of trichomes were positively related to fungal biomass of F. pseudograminearum in plants. PMID:27936004

The role of defoliation and root rot pathogen infection in driving the mode of drought-related physiological decline in Scots pine (Pinus sylvestris L.).

PubMed

Aguadé, D; Poyatos, R; Gómez, M; Oliva, J; Martínez-Vilalta, J

2015-03-01

Drought-related tree die-off episodes have been observed in all vegetated continents. Despite much research effort, however, the multiple interactions between carbon starvation, hydraulic failure and biotic agents in driving tree mortality under field conditions are still not well understood. We analysed the seasonal variability of non-structural carbohydrates (NSCs) in four organs (leaves, branches, trunk and roots), the vulnerability to embolism in roots and branches, native embolism (percentage loss of hydraulic conductivity (PLC)) in branches and the presence of root rot pathogens in defoliated and non-defoliated individuals in a declining Scots pine (Pinus sylvestris L.) population in the NE Iberian Peninsula in 2012, which included a particularly dry and warm summer. No differences were observed between defoliated and non-defoliated pines in hydraulic parameters, except for a higher vulnerability to embolism at pressures below -2 MPa in roots of defoliated pines. No differences were found between defoliation classes in branch PLC. Total NSC (TNSC, soluble sugars plus starch) values decreased during drought, particularly in leaves. Defoliation reduced TNSC levels across tree organs, especially just before (June) and during (August) drought. Root rot infection by the fungal pathogen Onnia P. Karst spp. was detected but it did not appear to be associated to tree defoliation. However, Onnia infection was associated with reduced leaf-specific hydraulic conductivity and sapwood depth, and thus contributed to hydraulic impairment, especially in defoliated pines. Infection was also associated with virtually depleted root starch reserves during and after drought in defoliated pines. Moreover, defoliated and infected trees tended to show lower basal area increment. Overall, our results show the intertwined nature of physiological mechanisms leading to drought-induced mortality and the inherent difficulty of isolating their contribution under field conditions. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Molecular characterization of pathogenic Fusarium species in cucurbit plants from Kermanshah province, Iran

PubMed Central

Chehri, K.; Salleh, B.; Yli-Mattila, T.; Reddy, K.R.N.; Abbasi, S.

2011-01-01

Fusarium is one of the important phytopathogenic genera of microfungi causing serious losses on cucurbit plants in Kermanshah province, the largest area of cucurbits plantation in Iran. Therefore, the objectives in this study were to isolate and identify disease-causing Fusarium spp. from infected cucurbit plants, to ascertain their pathogenicity, and to determine their phylogenetic relationships. A total of 100 Fusarium isolates were obtained from diseased cucurbit plants collected from fields in different geographic regions in Kermanshah province, Iran. According to morphological characters, all isolates were identified as Fusarium oxysporum, Fusarium proliferatum, Fusarium equiseti, Fusarium semitectum and Fusarium solani. All isolates of the five Fusarium spp. were evaluated for their pathogenicity on healthy cucumber (Cucumis sativus) and honeydew melon (Cucumis melo) seedlings in the glasshouse. F. oxysporum caused damping-off in 20–35 days on both cucurbit seedlings tested. Typical stem rot symptoms were observed within 15 days after inoculation with F. solani on both seedlings. Based on the internal transcribed spacer (ITS) regions of ribosomal DNA (rDNA) restriction fragment length polymorphism (RFLP) analysis, the five Fusarium species were divided into two major groups. In particular, isolates belonging to the F. solani species complex (FSSC) were separated into two RFLP types. Grouping among Fusarium strains derived from restriction analysis was in agreement with criteria used in morphological classification. Therefore, the PCR-ITS-RFLP method provides a simple and rapid procedure for the differentiation of Fusarium strains at species level. This is the first report on identification and pathogenicity of major plant pathogenic Fusarium spp. causing root and stem rot on cucurbits in Iran. PMID:23961146

Repeated Structures Found After the Solar Maximum in the Butterfly Diagrams of Coronal Holes

NASA Astrophysics Data System (ADS)

Hofer, M. Y.; Storini, M.

2003-09-01

The influence of the solar cycle evolution on the coronal hole space-time distribution is well known, for polar as well as for equatorial isolated sources of high speed solar wind. Among them the long-lived coronal holes occurrence from the sunspot cycle 21 on is investigated, using the coronal hole catalogue based on HeI (1083 nm) observations (Sanchez-Ibarra and Barraza-Paredes). In at least these two solar cycles (n. 21 and n. 22) a similar structure in the latitude-time diagram of coronal holes is found. The area occurs shortly after the solar maximum at around ~35° heliolatitude and consists of over several Carrington Rotations stable coronal holes (>5 Carr. Rot.s). The diagonal disappears 2-3 years later at the helioequator. Furthermore, the analysis results in a close relation between long-lived isolated coronal holes and the soft X-class flares.

PAMPs, PRRs, effectors and R-genes associated with citrus–pathogen interactions

PubMed Central

Dalio, Ronaldo J. D.; Magalhães, Diogo M.; Rodrigues, Carolina M.; Arena, Gabriella D.; Oliveira, Tiago S.; Souza-Neto, Reinaldo R.; Picchi, Simone C.; Martins, Paula M. M.; Santos, Paulo J. C.; Maximo, Heros J.; Pacheco, Inaiara S.; De Souza, Alessandra A.

2017-01-01

Abstract Background Recent application of molecular-based technologies has considerably advanced our understanding of complex processes in plant–pathogen interactions and their key components such as PAMPs, PRRs, effectors and R-genes. To develop novel control strategies for disease prevention in citrus, it is essential to expand and consolidate our knowledge of the molecular interaction of citrus plants with their pathogens. Scope This review provides an overview of our understanding of citrus plant immunity, focusing on the molecular mechanisms involved in the interactions with viruses, bacteria, fungi, oomycetes and vectors related to the following diseases: tristeza, psorosis, citrus variegated chlorosis, citrus canker, huanglongbing, brown spot, post-bloom, anthracnose, gummosis and citrus root rot. PMID:28065920

Evaluation of Muscodor suthepensis strain CMU-Cib462 as a postharvest biofumigant for tangerine fruit rot caused by Penicillium digitatum.

PubMed

Suwannarach, Nakarin; Bussaban, Boonsom; Nuangmek, Wipornpan; Pithakpol, Wasna; Jirawattanakul, Bantoon; Matsui, Kenji; Lumyong, Saisamorn

2016-01-15

This study investigated both the in vitro and in vivo biofumigant ability of the endophytic fungus Muscodor suthepensis CMU-Cib462 to control Penicillium digitatum, the main cause of tangerine fruit rot. Volatile compounds from M. suthepensis inhibited mycelial growth of the pathogen. The most abundant compound was 2-methylpropanoic acid, followed by 3-methylbutan-1-ol. They showed median effective doses (ED50) on P. digitatum growth of 74.91 ± 0.73 and 250.29 ± 0.29 µL L(-1) airspace respectively. Rye grain was found to be a suitable solid medium for M. suthepensis inoculum production. The results indicated that mycofumigation with a 30 g rye grain culture of M. suthepensis for 12 h controlled tangerine fruit rot. The percentage weight loss and soluble solids concentration of fumigated tangerines were similar to those of non-infected and non-fumigated fruits. Muscodor suthepensis has potential as a biofumigant for controlling postharvest disease of tangerine fruit. © 2015 Society of Chemical Industry.

Field survey and fungicide screening of fungal pathogens of rambutan (Nephelium lappaceum) fruit rot in Hawaii

USDA-ARS?s Scientific Manuscript database

Rambutan (Nephelium lappaceum Linn.) is a tropical fruit in Hawaii that has increased in value in the niche market of exotic fruits. The primary limitation to pre-harvest and post-harvest quality is the occurrence of fungal diseases of the fruit. A survey of rambutan disease was conducted in Hilo, H...

A North American isolate of Fusarium graminearum: toxicity and biosynthesis of a new type A trichothecene

USDA-ARS?s Scientific Manuscript database

Fusarium graminearum is one of the economically most important plant pathogens causing diseases such as Fusarium Head Blight (FHB) of small grain cereals and ear rot of maize. The mycotoxin deoxynivalenol (DON) produced by F. graminearum is a virulence factor in wheat and probably also on other host...

Analysis and mapping of Rhizoctonia root rot resistance traits from the synthetic wheat (Triticum aestivum L.) line SYN-172

USDA-ARS?s Scientific Manuscript database

The prevalence of root disease after planting in cold spring soils has hindered the adoption of reduced or no-tillage cereal cropping systems in the Pacific Northwest. In particular, Rhizoctonia solani AG-8, a necrotrophic root pathogen, can cause significant damage to wheat stands under these cond...

Impact of temperature stress and validamycin A on compatible solutes and fumonisin production in F. verticillioides: Role of trehalose-6-phosphate synthase

USDA-ARS?s Scientific Manuscript database

Fusarium verticillioides is a pathogen of maize that causes root, stalk, and ear rot and produces fumonisins, toxic secondary metabolites associated with disease in livestock and humans. Environmental stresses such as heat and drought influence disease severity and toxin production, but the effects ...

Macrofungi on woody substrata

Treesearch

Sabine M. Huhndorf; D. J. Lodge; Chun-Juan Wang; Jogeir N. Stokland

2004-01-01

Wood-inhabiting macrofungi inhabit substrata that differ in size, state of decay, and moisture content. Thus, the ecologies of fungi growing on wood differ. Wood-inhabiting species include fungi that were in or on the wood when a tree or tree part fell to the ground (e.g., pathogens and nonpathogenic endophytes of living tissue, heart rots), as well as the succession...

First report of Monilinia fructicola causing postharvest decay of strawberries (Fragaria ananassa) in the United States

USDA-ARS?s Scientific Manuscript database

Monilinia fructicola is a world-wide economically important pathogen of stone fruits causing brown rot before and after harvest. In early summer of 2016, signs of Monilinia spp. decay were observed on strawberry fruit, harvested from organically grown plants in a high tunnel located in the middle o...

Molecules that inhibit growth of Fusarium graminearum, a pathogen causing disease in wheat and corn

USDA-ARS?s Scientific Manuscript database

Fusarium graminearum can cause head blight in wheat and stalk or ear rot in corn, which results in crop losses. Discovery of novel antifungal resistance proteins are crucial to mitigating crop losses. We found, via in vitro studies, a small cationic peptide was capable of inhibiting the growth of th...

Carbon source-dependent efficacy of anaerobic soil disinfestation (ASD) in suppression of Rhizoctonia root rot of apple

USDA-ARS?s Scientific Manuscript database

Rhizoctonia solani AG-5 is a significant component of the pathogen complex that incites apple replant disease (ARD). A non-fumigant alternative, such as ASD, is highly desired for control of ARD. We examined the influence of carbon input as a determinant of ASD efficacy in the supression of apple ...

Analysis and mapping of Rhizoctonia root rot resistance traits from the synthetic wheat (Triticum aestivum L) line SYN-172

USDA-ARS?s Scientific Manuscript database

The prevalence of root disease after planting in cold spring soils has hindered the adoption of reduced or no-tillage cereal cropping systems in the Pacific Northwest. In particular, Rhizoctonia solani AG8, a necrotrophic root pathogen, can cause significant damage to wheat stands under these condi...

Identification of a chitinase modifying protein from Fusarium verticillioides: truncation of a host resistance protein by a fungalysin metalloprotease

USDA-ARS?s Scientific Manuscript database

Chitinase modifying proteins (cmps) are proteases, secreted by fungal pathogens, which truncate the plant class IV chitinases ChitA and ChitB during maize ear rot. Cmp activity has been characterized for Bipolaris zeicola and Stenocarpella maydis, but the identities of the proteases are not known. H...

Cloning and identification of Fv-cmp, a protease from Fusarium verticillioides that truncates Zea mays and Arabidopsis thaliana class IV chitinases

USDA-ARS?s Scientific Manuscript database

Chitinase modifying proteins (cmps) are proteases, secreted by fungal pathogens, that were originally identified as proteins that truncate class IV chitinases of maize during ear rot. Cmps from Bipolaris zeicola and Stenocarpella maydis have been characterized, but the identities of the proteases h...

Controlling Infectious Diseases in Nurseries

Treesearch

T. H. Filer

1968-01-01

At least 300 publications have been written about non-infectious and infectious diseases of tree seedlings. I will outline some of the progress that is being made in finding ways to control infectious diseases, those caused by pathogens. I will touch upon pre- and post-emergence damping-off, root rots, leaf spots, and fusiform rust, which are the most serious diseases...

Species diversity and toxigenic potential of Fusarium graminearum complex isolates from maize fields in northwest Argentina

USDA-ARS?s Scientific Manuscript database

Members of the Fusarium graminearum species complex (Fg complex) are the causal agents of ear rot in maize and Fusarium head blight of wheat and other small grain cereals. The potential of these pathogens to contaminate cereals with trichothecene mycotoxins is a health risk for both humans and anima...

[Features of interaction bacterial strains Micrococcus luteus LBK1 from plants varieties/hybrids cucumber and sweet pepper and with fungus Fusarium oxysporum Scelecht].

PubMed

Parfeniuk, A; Sterlikova, O; Beznosko, I; Krut', V

2014-01-01

The article presents the results of studying the impact of bacterial strain M. luteus LBK1, stimulating the growth and development of plant varieties/hybrids of cucumber and sweet pepper on the intensity of sporulation of the fungus F. oxysporum Scelecht--fusariose rot pathogen.

Influence of electron beam irradiation on growth of Phytophthora cinnamomi and its control in substrates

NASA Astrophysics Data System (ADS)

MigdaŁ, Wojciech; Orlikowski, Leszek B.; Ptaszek, Magdalena; Gryczka, Urszula

2012-08-01

Very extensive production procedure, especially in plants growing under covering, require methods, which would allow quick elimination or substantial reduction of populations of specific pathogens without affecting the growth and development of the cultivated plants. Among soil-borne pathogens, the Phytophthora species are especially dangerous for horticultural plants. In this study, irradiation with electron beam was applied to control Phytophthora cinnamomi. The influence of irradiation dose on the reduction of in vitro growth and the population density of the pathogen in treated peat and its mixture with composted pine bark (1:1), as well as the health of Chamaecyparis lawsoniana and Lavandula angustifolia plants were evaluated. Application of irradiation at a dose of 1.5 kGy completely inhibited the in vitro development of P. cinnamomi. This irradiation effect was connected with the disintegration of the hyphae and spores of the species. Irradiation of peat and its mixture with composted pine bark with 10 kGy resulted in the inhibition of stem base rot development in Ch. lawsoniana. Symptoms of the disease were not observed when the substrates were treated with 15 kGy. In the case of L. angustifolia, stem root rot was not observed on cuttings transplanted to infected peat irradiated at a dose of 10 kGy. Irradiation of the horticultural substrates did not affect plant growth.

GmPGIP3 enhanced resistance to both take-all and common root rot diseases in transgenic wheat.

PubMed

Wang, Aiyun; Wei, Xuening; Rong, Wei; Dang, Liang; Du, Li-Pu; Qi, Lin; Xu, Hui-Jun; Shao, Yanjun; Zhang, Zengyan

2015-05-01

Take-all (caused by the fungal pathogen Gaeumannomyces graminis var. tritici, Ggt) and common root rot (caused by Bipolaris sorokiniana) are devastating root diseases of wheat (Triticum aestivum L.). Development of resistant wheat cultivars has been a challenge since no resistant wheat accession is available. GmPGIP3, one member of polygalacturonase-inhibiting protein (PGIP) family in soybean (Glycine max), exhibited inhibition activity against fungal endopolygalacturonases (PGs) in vitro. In this study, the GmPGIP3 transgenic wheat plants were generated and used to assess the effectiveness of GmPGIP3 in protecting wheat from the infection of Ggt and B. sorokiniana. Four independent transgenic lines were identified by genomic PCR, Southern blot, and reverse transcription PCR (RT-PCR). The introduced GmPGIP3 was integrated into the genomes of these transgenic lines and could be expressed. The expressing GmPGIP3 protein in these transgenic wheat lines could inhibit the PGs produced by Ggt and B. sorokiniana. The disease response assessments postinoculation showed that the GmPGIP3-expressing transgenic wheat lines displayed significantly enhanced resistance to both take-all and common root rot diseases caused by the infection of Ggt and B. sorokiniana. These data suggested that GmPGIP3 is an attractive gene resource in improving resistance to both take-all and common root rot diseases in wheat.

Detection and Identification of Decay Fungi in Spruce Wood by Restriction Fragment Length Polymorphism Analysis of Amplified Genes Encoding rRNA†

PubMed Central

Jasalavich, Claudia A.; Ostrofsky, Andrea; Jellison, Jody

2000-01-01

We have developed a DNA-based assay to reliably detect brown rot and white rot fungi in wood at different stages of decay. DNA, isolated by a series of CTAB (cetyltrimethylammonium bromide) and organic extractions, was amplified by the PCR using published universal primers and basidiomycete-specific primers derived from ribosomal DNA sequences. We surveyed 14 species of wood-decaying basidiomycetes (brown-rot and white-rot fungi), as well as 25 species of wood-inhabiting ascomycetes (pathogens, endophytes, and saprophytes). DNA was isolated from pure cultures of these fungi and also from spruce wood blocks colonized by individual isolates of wood decay basidiomycetes or wood-inhabiting ascomycetes. The primer pair ITS1-F (specific for higher fungi) and ITS4 (universal primer) amplified the internal transcribed spacer region from both ascomycetes and basidiomycetes from both pure culture and wood, as expected. The primer pair ITS1-F (specific for higher fungi) and ITS4-B (specific for basidiomycetes) was shown to reliably detect the presence of wood decay basidiomycetes in both pure culture and wood; ascomycetes were not detected by this primer pair. We detected the presence of decay fungi in wood by PCR before measurable weight loss had occurred to the wood. Basidiomycetes were identified to the species level by restriction fragment length polymorphisms of the internal transcribed spacer region. PMID:11055916

Role and Regulation of the Flp/Tad Pilus in the Virulence of Pectobacterium atrosepticum SCRI1043 and Pectobacterium wasabiae SCC3193

PubMed Central

Nykyri, Johanna; Mattinen, Laura; Niemi, Outi; Adhikari, Satish; Kõiv, Viia; Somervuo, Panu; Fang, Xin; Auvinen, Petri; Mäe, Andres; Palva, E. Tapio; Pirhonen, Minna

2013-01-01

In this study, we characterized a putative Flp/Tad pilus-encoding gene cluster, and we examined its regulation at the transcriptional level and its role in the virulence of potato pathogenic enterobacteria of the genus Pectobacterium. The Flp/Tad pilus-encoding gene clusters in Pectobacterium atrosepticum, Pectobacterium wasabiae and Pectobacterium aroidearum were compared to previously characterized flp/tad gene clusters, including that of the well-studied Flp/Tad pilus model organism Aggregatibacter actinomycetemcomitans, in which this pilus is a major virulence determinant. Comparative analyses revealed substantial protein sequence similarity and open reading frame synteny between the previously characterized flp/tad gene clusters and the cluster in Pectobacterium, suggesting that the predicted flp/tad gene cluster in Pectobacterium encodes a Flp/Tad pilus-like structure. We detected genes for a novel two-component system adjacent to the flp/tad gene cluster in Pectobacterium, and mutant analysis demonstrated that this system has a positive effect on the transcription of selected Flp/Tad pilus biogenesis genes, suggesting that this response regulator regulate the flp/tad gene cluster. Mutagenesis of either the predicted regulator gene or selected Flp/Tad pilus biogenesis genes had a significant impact on the maceration ability of the bacterial strains in potato tubers, indicating that the Flp/Tad pilus-encoding gene cluster represents a novel virulence determinant in Pectobacterium. Soft-rot enterobacteria in the genera Pectobacterium and Dickeya are of great agricultural importance, and an investigation of the virulence of these pathogens could facilitate improvements in agricultural practices, thus benefiting farmers, the potato industry and consumers. PMID:24040039

Role and regulation of the Flp/Tad pilus in the virulence of Pectobacterium atrosepticum SCRI1043 and Pectobacterium wasabiae SCC3193.

PubMed

Nykyri, Johanna; Mattinen, Laura; Niemi, Outi; Adhikari, Satish; Kõiv, Viia; Somervuo, Panu; Fang, Xin; Auvinen, Petri; Mäe, Andres; Palva, E Tapio; Pirhonen, Minna

2013-01-01

In this study, we characterized a putative Flp/Tad pilus-encoding gene cluster, and we examined its regulation at the transcriptional level and its role in the virulence of potato pathogenic enterobacteria of the genus Pectobacterium. The Flp/Tad pilus-encoding gene clusters in Pectobacterium atrosepticum, Pectobacterium wasabiae and Pectobacterium aroidearum were compared to previously characterized flp/tad gene clusters, including that of the well-studied Flp/Tad pilus model organism Aggregatibacter actinomycetemcomitans, in which this pilus is a major virulence determinant. Comparative analyses revealed substantial protein sequence similarity and open reading frame synteny between the previously characterized flp/tad gene clusters and the cluster in Pectobacterium, suggesting that the predicted flp/tad gene cluster in Pectobacterium encodes a Flp/Tad pilus-like structure. We detected genes for a novel two-component system adjacent to the flp/tad gene cluster in Pectobacterium, and mutant analysis demonstrated that this system has a positive effect on the transcription of selected Flp/Tad pilus biogenesis genes, suggesting that this response regulator regulate the flp/tad gene cluster. Mutagenesis of either the predicted regulator gene or selected Flp/Tad pilus biogenesis genes had a significant impact on the maceration ability of the bacterial strains in potato tubers, indicating that the Flp/Tad pilus-encoding gene cluster represents a novel virulence determinant in Pectobacterium. Soft-rot enterobacteria in the genera Pectobacterium and Dickeya are of great agricultural importance, and an investigation of the virulence of these pathogens could facilitate improvements in agricultural practices, thus benefiting farmers, the potato industry and consumers.

Isolation, characterization, and formulation of antagonistic bacteria for the management of seedlings damping-off and root rot disease of cucumber.

PubMed

Khabbaz, Salah Eddin; Abbasi, Pervaiz A

2014-01-01

Antagonistic bacteria are common soil inhabitants with potential to be developed into biofungicides for the management of seedling damping-off, root rot, and other soil-borne diseases of various crops. In this study, antagonistic bacteria were isolated from a commercial potato field and screened for their growth inhibition of fungal and oomycete pathogens in laboratory tests. The biocontrol potential of the 3 most effective antagonistic bacteria from the in vitro tests was evaluated against seedling damping-off and root rot of cucumber caused by Pythium ultimum. Based on phenotypic characteristics, biochemical tests, and sequence analysis of 16S-23S rDNA gene, the 3 antagonistic bacteria were identified as Pseudomonas fluorescens (isolate 9A-14), Pseudomonas sp. (isolate 8D-45), and Bacillus subtilis (isolate 8B-1). All 3 bacteria promoted plant growth and suppressed Pythium damping-off and root rot of cucumber seedlings in growth-room assays. Both pre- and post-planting application of these bacteria to an infested peat mix significantly increased plant fresh masses by 113%-184% and percentage of healthy seedlings by 100%-290%, and decreased damping-off and root rot severity by 27%-50%. The peat and talc formulations of these antagonistic bacteria applied as seed or amendment treatments to the infested peat mix effectively controlled Pythium damping-off and root rot of cucumber seedlings and enhanced plant growth. The survival of all 3 antagonistic bacteria in peat and talc formulations decreased over time at room temperature, but the populations remained above 10(8) CFU/g during the 180-day storage period. The peat formulation of a mixture of 3 bacteria was the best seed treatment, significantly increasing the plant fresh masses by 245% as compared with the Pythium control, and by 61.4% as compared with the noninfested control. This study suggests that the indigenous bacteria from agricultural soils can be developed and formulated as biofungicides for minimizing the early crop losses caused by seedling damping-off and root rot diseases.

Research on basal stem rot (BSR) of ornamental palms caused by basidiospores from Ganoderma boninense.

PubMed

Lim, H P; Fong, Y K

2005-01-01

Basidiospores were isolated from the fruiting bodies of Ganoderma infecting oil palms from an estate in Johor and from ornamental palms (including oil palms) from Singapore. The spores were then germinated to obtain homokaryotic mycelia. Based on clamp connection formation in paired hyphal fusions, tester strains were identified from the homokaryons isolated. Compatibility tests were then carried out using these testers to determine the relatedness of the homokaryotic Ganoderma isolates, both from Johor and from Singapore. Results from the compatibility tests showed that Ganoderma from both locations belong to the same species, while the Ganoderma isolates from Singapore share some common alleles. The pathogenicity tests carried out on Chrysalidocarpus lutescens seedlings using inoculum growing on rubber wood blocks showed that dikaryotic mycelia can cause basal stem rot infection.

Recent Developments in Using Advanced Sequencing Technologies for the Genomic Studies of Lignin and Cellulose Degrading Microorganisms

PubMed Central

Kameshwar, Ayyappa kumar Sista; Qin, Wensheng

2016-01-01

Lignin is a complex polyphenyl aromatic compound which exists in tight associations with cellulose and hemicellulose to form plant primary and secondary cell wall. Lignocellulose is an abundant renewable biomaterial present on the earth. It has gained much attention in the scientific community in recent years because of its potential applications in bio-based industries. Microbial degradation of lignocellulose polymers was well studied in wood decaying fungi. Based on the plant materials they degrade these fungi were classified as white rot, brown rot and soft rot. However, some groups of bacteria belonging to the actinomycetes, α-proteobacteria and β-proteobacteria were also found to be efficient in degrading lignocellulosic biomass but not well understood unlike the fungi. In this review we focus on recent advancements deployed for finding and understanding the lignocellulose degradation by microorganisms. Conventional molecular methods like sequencing 16s rRNA and Inter Transcribed Spacer (ITS) regions were used for identification and classification of microbes. Recent progression in genomics mainly next generation sequencing technologies made the whole genome sequencing of microbes possible in a great ease. The whole genome sequence studies reveals high quality information about genes and canonical pathways involved in the lignin and other cell wall components degradation. PMID:26884714

Comparative Pathogenomics Reveals Horizontally Acquired Novel Virulence Genes in Fungi Infecting Cereal Hosts

PubMed Central

Gardiner, Donald M.; McDonald, Megan C.; Covarelli, Lorenzo; Solomon, Peter S.; Rusu, Anca G.; Marshall, Mhairi; Kazan, Kemal; Chakraborty, Sukumar; McDonald, Bruce A.; Manners, John M.

2012-01-01

Comparative analyses of pathogen genomes provide new insights into how pathogens have evolved common and divergent virulence strategies to invade related plant species. Fusarium crown and root rots are important diseases of wheat and barley world-wide. In Australia, these diseases are primarily caused by the fungal pathogen Fusarium pseudograminearum. Comparative genomic analyses showed that the F. pseudograminearum genome encodes proteins that are present in other fungal pathogens of cereals but absent in non-cereal pathogens. In some cases, these cereal pathogen specific genes were also found in bacteria associated with plants. Phylogenetic analysis of selected F. pseudograminearum genes supported the hypothesis of horizontal gene transfer into diverse cereal pathogens. Two horizontally acquired genes with no previously known role in fungal pathogenesis were studied functionally via gene knockout methods and shown to significantly affect virulence of F. pseudograminearum on the cereal hosts wheat and barley. Our results indicate using comparative genomics to identify genes specific to pathogens of related hosts reveals novel virulence genes and illustrates the importance of horizontal gene transfer in the evolution of plant infecting fungal pathogens. PMID:23028337

Signum, a new fungicide with interesting properties in resistance management of fungal diseases in strawberries.

PubMed

Hauke, K; Creemers, P; Brugmans, W; Van Laer, S

2004-01-01

Signum, a new fungicide developed by BASF, was applied during 6 successive years against fungal diseases in strawberries. The product is formulated as a water dispersible granule, containing 6.7 % pyraclostrobin and 26.7 % boscalid. Pyraclostrobin is similar in chemistry to other strobilurin fungicides like kresoxim-methyl and trifloxystrobin, registered for fruit disease control. Boscalid belongs to the class of carboxyanilides. Both components in the premix formulation combine two different biochemical modes of action in the fungal cell respiration. Therefore, this co-formulation gives a broad-spectrum activity and also a reduced resistance risk for different target pathogens. Botrytis cinerea is the most important disease on strawberry-fruits and thus the control of fruit rot is mainly focused on this fungus. In average over 6 years, Signum has not only given a very good control against Botrytis fruit rot, but it has also shown a high performance in the control of Colletotrichum. Besides, Signum provides good control of powdery mildew (Podosphaera aphanis) and limits the shift to other fruit rots like leather rot (Phytophthora cactorum and leak (Rhizopus, Mucor). The availability of several categories of fungicide families with a different mode of action gives opportunities in alternating different fungicides and is the best guarantee for a sustainable control of fruit rot in all kinds of strawberry production methods. Signum should be integrated in an overall disease management program. Trials, in which the applications of Signum were timed on disease forecasting, based on environmental factors favorable for Botrytis development, were very promising. This tool can also help in establishing the IPM-concept in the production of strawberries.

Control of Fusarium verticillioides, cause of ear rot of maize, by Pseudomonas fluorescens.

PubMed

Nayaka, Siddaiah Chandra; Shankar, Arakere C Udaya; Reddy, Munagala S; Niranjana, Siddapura R; Prakash, Harishchandra S; Shetty, Hunthrike S; Mortensen, Carmen N

2009-07-01

Maize is one of the staple food crops grown in India. Fusarium verticillioides (Sacc.) Nirenberg is the most important fungal pathogen of maize, associated with diseases such as ear rot and kernel rot. Apart from the disease, it is capable of producing fumonisins, which have elicited considerable attention over the past decade owing to their association with animal disease syndromes. Hence, the present study was conducted to evaluate ecofriendly approaches by using a maize rhizosphere isolate of Pseudomonas fluorescens (Trev.) Mig. and its formulation to control ear rot disease and fumonisin accumulation, and also to study the capacity to promote growth and yield of maize. In vitro assays were conducted to test the efficacy of P. fluorescens as a seed treatment on seed germination, seedling vigour and also the incidence of F. verticillioides in different maize cultivars. The field trials included both seed treatment and foliar spray. For all the experiments, P. fluorescens was formulated using corn starch, wheat bran and talc powder. In each case there were three different treatments of P. fluorescens, a non-treated control and chemical control. Pure culture and the formulations, in comparison with the control, increased plant growth and vigour as measured by seed germination, seedling vigour, plant height, 1000 seed weight and yield. P. fluorescens pure culture used as seed treatment and as spray treatment enhanced the growth parameters and reduced the incidence of F. verticillioides and the level of fumonisins to a maximum extent compared with the other treatments. The study demonstrates the potential role of P. fluorescens and its formulations in ear rot disease management. The biocontrol potential of this isolate is more suited for fumonisin reduction in maize kernels intended for human and animal feed. (c) 2009 Society of Chemical Industry.

Evaluation of a portable MOS electronic nose to detect root rots in shade tree species

Treesearch

Manuela Baietto; Letizia Pozzi; Alphus Dan Wilson; Daniele Bassi

2013-01-01

The early detection of wood decays in high-value standing trees is very important in urban areas because mitigating control measures must be implemented long before tree failures result in property damage or injuries to citizens. Adverse urban environments increase physiological stresses in trees, causing greater susceptibility to attacks by pathogenic decay fungi. The...

Distribution, identification, and quantification of residues after treatment of ready-to-eat salami with 36Cl-labeled or nonlabeled chlorine dioxide gas

USDA-ARS?s Scientific Manuscript database

Chlorine dioxide gas actively eliminates a variety of food-borne pathogens and rot organisms, including Listeria monocytogenes on food and food preparation surfaces. However the disposition and fate of chlorine dioxide gas on ready-to-eat meat products has not been previously described. When ready-t...

Tuber resistance and slow rotting characteristics of potato clones associated with the Solanaceae Coordinated Agricultural Project to the US-24 clonal lineage of Phytophthora infestans

USDA-ARS?s Scientific Manuscript database

Late blight, caused by Phytophthora infestans, is a devastating disease on potato worldwide and new lineages of the pathogen continue to develop in the U.S. Breeding for resistance is important for economic and environmental purposes. The Solanaceae Coordinated Agricultural Project (SolCAP) focuses ...

Volatile organic compounds produced by antarctic strains of candida sake play a role in the control of postharvest pathogens of apples

USDA-ARS?s Scientific Manuscript database

In this study the strategy of isolating psychrotrophic, non-pectinolytic yeasts able to grow in apple juice as potential biocontrol agents was a successful approach. Thirty-four yeasts isolated from Antarctic were able to maintain rot incidence caused by P. expansum and B. cinerea under 25% on appl...

A Multiyear Study on Seasonal Flight Activity Based on Captures of Southern Green Stink Bug (Hemiptera: Pentatomidae) in Blacklight Traps in Central Texas

USDA-ARS?s Scientific Manuscript database

The southern green stink bug, Nezara viridula (L.) (Hemiptera: Pentatomidae), is cosmopolitan in distribution and feeds on many cultivated plants. On cotton, it reduces yield and transmits fungal and bacterial pathogens that result in necrosis of the locule and boll rotting. Objectives of this study...

Genetic and genomic resources for mapping resistance to Phytophthora cinnamomi in chestnut

Treesearch

T. Zhebentyayeva; A. Chandra; A.G. Abbott; M.E. Staton; B.A. Olukolu; F.V. Hebard; L.L. Georgi; S.N. Jeffers; P.H. Sisco; J.B. James; C. Dana Nelson

2013-01-01

Root rot (caused by Phytophthora cinnamomi) and chestnut blight (caused by Cryphonectria parasitica) are the two most destructive diseases affecting American chestnut, Castanea dentata. Therefore, breeding for resistance to both pathogens simultaneously is essential before the American chestnut can be restored to its full native range. Using combined genetic and...

Plant growth-promoting Methylobacterium induces defense responses in groundnut (Arachis hypogaea L.) compared with rot pathogens.

PubMed

Madhaiyan, M; Suresh Reddy, B V; Anandham, R; Senthilkumar, M; Poonguzhali, S; Sundaram, S P; Sa, Tongmin

2006-10-01

This study, framed in two different phases, studied the plant-growth promotion and the induction of systemic resistance in groundnut by Methylobacterium. Seed imbibition with Methylobacterium sp. increased germination by 19.5% compared with controls. Combined inoculation of Methylobacterium sp. with Rhizobium sp. also significantly increased plant growth, nodulation, and yield attributes in groundnut compared with individual inoculation of Rhizobium sp. Methylobacterium sp. challenge-inoculated with Aspergillus niger/Sclerotium rolfsii in groundnut significantly enhanced germination percentage and seedling vigour and showed increased phenylalanine ammonia lyase (PAL), beta-1,3-glucanase, and peroxidase (PO) activities. Under pot-culture conditions, in Methylobacterium sp. seed-treated groundnut plants challenge-inoculated with A. niger/S. rolfsii through foliar sprays on day 30, the activities of enzymes PO, PAL, and beta-1,3-glucanase increased constantly from 24 to 72 hours, after which decreased activity was noted. Five isozymes of polyphenol oxidase and PO could be detected in Methylobacterium-treated plants challenged with A. niger/S. rolfsii. Induced systemic resistance activity in groundnut against rot pathogens in response to methylotrophic bacteria suggests the possibility that pink-pigmented facultative methylotrophic bacteria might be used as a means of biologic disease control.

Endophytic Paraconiothyrium sp. from Zingiber officinale Rosc. Displays Broad-Spectrum Antimicrobial Activity by Production of Danthron.

PubMed

Anisha, C; Sachidanandan, P; Radhakrishnan, E K

2018-03-01

The bioactivity spectrum of fungal endophytes isolated from Zingiber officinale was analyzed against clinical pathogens and against the phytopathogen Pythium myriotylum, which causes Pythium rot in ginger. One of the isolates GFM13 showed broad bioactivity against various pathogens tested including P. myriotylum. The spore suspension as well as the culture filtrate of the endophytic fungal isolate was found to effectively protect ginger rhizomes from Pythium rot. By molecular identification, the fungal endophyte was identified as Paraconiothyrium sp. The bioactive compound produced by the isolate was separated by bioactivity-guided fractionation and was identified by GC-MS as danthron, an anthraquinone derivative. PCR amplification showed the presence of non-reducing polyketide synthase gene (NR-PKS) in the endophyte GFM13, which is reported to be responsible for the synthesis of anthraquinones in fungi. This is the first report of danthron being produced as the biologically active component of Paraconiothyrium sp. Danthron is reported to have wide pharmaceutical and agronomic applications which include its use as a fungicide in agriculture. The broad-spectrum antimicrobial activity of danthron and the endophytic origin of Paraconiothyrium sp. offer immense applications of the study.

Genes associated with lignin degradation in the polyphagous white-rot pathogen Heterobasidion irregulare show substrate-specific regulation.

PubMed

Yakovlev, Igor A; Hietala, Ari M; Courty, Pierre-Emmanuel; Lundell, Taina; Solheim, Halvor; Fossdal, Carl Gunnar

2013-07-01

The pathogenic white-rot basidiomycete Heterobasidion irregulare is able to remove lignin and hemicellulose prior to cellulose during the colonization of root and stem xylem of conifer and broadleaf trees. We identified and followed the regulation of expression of genes belonging to families encoding ligninolytic enzymes. In comparison with typical white-rot fungi, the H. irregulare genome has exclusively the short-manganese peroxidase type encoding genes (6 short-MnPs) and thereby a slight contraction in the pool of class II heme-containing peroxidases, but an expansion of the MCO laccases with 17 gene models. Furthermore, the genome shows a versatile set of other oxidoreductase genes putatively involved in lignin oxidation and conversion, including 5 glyoxal oxidases, 19 quinone-oxidoreductases and 12 aryl-alcohol oxidases. Their genetic multiplicity and gene-specific regulation patterns on cultures based on defined lignin, cellulose or Norway spruce lignocellulose substrates suggest divergent specificities and physiological roles for these enzymes. While the short-MnP encoding genes showed similar transcript levels upon fungal growth on heartwood and reaction zone (RZ), a xylem defense tissue rich in phenolic compounds unique to trees, a subset of laccases showed higher gene expression in the RZ cultures. In contrast, other oxidoreductases depending on initial MnP activity showed generally lower transcript levels on RZ than on heartwood. These data suggest that the rate of fungal oxidative conversion of xylem lignin differs between spruce RZ and heartwood. It is conceivable that in RZ part of the oxidoreductase activities of laccases are related to the detoxification of phenolic compounds involved in host-defense. Expression of the several short-MnP enzymes indicated an important role for these enzymes in effective delignification of wood by H. irregulare. Copyright © 2013 Elsevier Inc. All rights reserved.

A transposon-directed epigenetic change in ZmCCT underlies quantitative resistance to Gibberella stalk rot in maize.

PubMed

Wang, Chao; Yang, Qin; Wang, Weixiang; Li, Yipu; Guo, Yanling; Zhang, Dongfeng; Ma, Xuena; Song, Wei; Zhao, Jiuran; Xu, Mingliang

2017-09-01

A major resistance quantitative trait locus, qRfg1, significantly enhances maize resistance to Gibberella stalk rot, a devastating disease caused by Fusarium graminearum. However, the underlying molecular mechanism remains unknown. We adopted a map-based cloning approach to identify the resistance gene at qRfg1 and examined the dynamic epigenetic changes during qRfg1-mediated maize resistance to the disease. A CCT domain-containing gene, ZmCCT, is the causal gene at the qRfg1 locus and a polymorphic CACTA-like transposable element (TE1) c. 2.4 kb upstream of ZmCCT is the genetic determinant of allelic variation. The non-TE1 ZmCCT allele is in a poised state, with predictive bivalent chromatin enriched for both repressive (H3K27me3/H3K9me3) and active (H3K4me3) histone marks. Upon pathogen challenge, this non-TE1 ZmCCT allele was promptly induced by a rapid yet transient reduction in H3K27me3/H3K9me3 and a progressive decrease in H3K4me3, leading to disease resistance. However, TE1 insertion in ZmCCT caused selective depletion of H3K4me3 and enrichment of methylated GC to suppress the pathogen-induced ZmCCT expression, resulting in disease susceptibility. Moreover, ZmCCT-mediated resistance to Gibberella stalk rot is not affected by photoperiod sensitivity. This chromatin-based regulatory mechanism enables ZmCCT to be more precise and timely in defense against F. graminearum infection. © 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.

Effect of seed pelleting with biocontrol agents on growth and colonisation of roots of mungbean by root-infecting fungi.

PubMed

Ramzan, Nadia; Noreen, Nayara; Perveen, Zahida; Shahzad, Saleem

2016-08-01

Mungbean (Vigna radiata (L.) Wilczek) is a leguminous pulse crop that is a major source of proteins, vitamins and minerals. Root-infecting fungi produce severe plant diseases like root rot, charcoal rot, damping-off and stem rot. The soil-borne pathogens can be controlled by chemicals, but these chemicals have several negative effects. Use of microbial antagonist such as fungi and bacteria is a safe, effective and eco-friendly method for the control of many soil-borne pathogens. Biological control agents promote plant growth and develop disease resistance. Application of bacteria and fungi as seed dressing suppressed the root-infecting fungi on leguminous crops. Seeds of mungbean were pelleted with different biocontrol agents to determine their effect on plant growth and colonisation of roots by root-infecting fungi, viz. Fusarium solani, Macrophomina phaseolina, Pythium aphanidermatum, Rhizoctonia solani and Sclerotium rolfsii. Treatment of mungbean seeds with fungal antagonists showed more shoot and root length as compared to bacterial antagonists, whereas seed treated with bacterial antagonists showed maximum shoot and root weight. Trichoderma harzianum and Bacillus subtilis were the best among all the biocontrol agents since they provided the highest plant growth and greater reduction in root colonisation by all root-infecting fungi. Bacillus cereus, Trichoderma virens, Pseudomonas fluorescens and Micrococcus varians were also effective against root-infecting fungi but to a lesser extent. T. harzianum, T. virens, B. subtilis and P. fluorescens were found to be best among all biocontrol agents. The root-infecting fungi can be controlled by pelleting seeds with biocontrol agents as it is safe and effective method. Additionally, plant growth was promoted more by this method. © 2015 Society of Chemical Industry. © 2015 Society of Chemical Industry.

Efficacy of plant essential oils on postharvest control of rots caused by fungi on different stone fruits in vivo.

PubMed

Lopez-Reyes, Jorge Giovanny; Spadaro, Davide; Prelle, Ambra; Garibaldi, Angelo; Gullino, Maria Lodovica

2013-04-01

The antifungal activity of plant essential oils was evaluated as postharvest treatment on stone fruit against brown rot and grey mold rot of stone fruit caused by Monilinia laxa and Botrytis cinerea, respectively. The essential oils from basil (Ocimum basilicum), fennel (Foeniculum sativum), lavender (Lavandula officinalis), marjoram (Origanum majorana), oregano (Origanum vulgare), peppermint (Mentha piperita), rosemary (Rosmarinus officinalis), sage (Salvia officinalis), savory (Satureja montana), thyme (Thymus vulgaris), and wild mint (Mentha arvensis) were tested at two different concentrations on apricots (cv. Kyoto and cv. Tonda di Costigliole), nectarines (cv. Big Top and cv. Nectaross) and plums (cv. Italia and cv. TC Sun). The volatile composition of the essential oils tested was determined by gas chromatography-mass spectrometry analysis. The treatments containing essential oils from oregano, savory, and thyme at 1% (vol/vol) controlled both B. cinerea and M. laxa growing on apricots cv. Tonda di Costigliole and plums cv. Italia and cv. TC Sun; however, the same treatments were phytotoxic for the carposphere of nectarines cv. Big Top and cv. Nectaross. Treatments with 10% (vol/vol) essential oils were highly phytotoxic, notwithstanding their efficacy against the pathogens tested. The essential oils containing as major components α-pinene, p-cymene, carvacrol, and thymol showed similar results on stone fruit, so their antimicrobial activity and the phytotoxicity produced could be based on the concentration of their principal compounds and their synergistic activity. The efficacy of the essential oil treatments on control of fungal pathogens in postharvest depended on the fruit cultivar, the composition and concentration of the essential oil applied, and the length of storage.

Isolation of Dickeya dadantii strains from potato disease and biocontrol by their bacteriophages.

PubMed

Soleimani-Delfan, Abbas; Etemadifar, Zahra; Emtiazi, Giti; Bouzari, Majid

2015-01-01

One of the most economically important bacterial pathogens of plants and plant products is Dickeya dadantii. This bacterium causes soft rot disease in tubers and other parts of the potato and other plants of the Solanaceae family. The application of restricted host range bacteriophages as biocontrol agents has recently gained widespread interest. This study purposed to isolate the infectious agent of the potato and evaluate its biocontrol by bacteriophages. Two phytopathogenic strains were isolated from infected potatoes, identified based on biochemical and 16S rRNA gene sequencing, and submitted to GenBank as D. dadantii strain pis3 (accession no. HQ423668) and D. dadantii strain sip4 (accession no. HQ423669). Their bacteriophages were isolated from Caspian Sea water by enriching the water filtrate with D. dadantii strains as hosts using spot or overlay methods. On the basis of morphotypes, the isolated bacteriophages were identified as members of the Myoviridae and Siphoviridae families and could inhibit the growth of antibiotic resistant D. dadantii strains in culture medium. Moreover, in Dickeya infected plants treated with bacteriophage, no disease progression was detected. No significant difference was seen between phage-treated and control plants. Thus, isolated bacteriophages can be suggested for the biocontrol of plant disease caused by Dickeya strains.

Plant phenolic volatiles inhibit quorum sensing in pectobacteria and reduce their virulence by potential binding to ExpI and ExpR proteins

NASA Astrophysics Data System (ADS)

Joshi, Janak Raj; Khazanov, Netaly; Senderowitz, Hanoch; Burdman, Saul; Lipsky, Alexander; Yedidia, Iris

2016-12-01

Quorum sensing (QS) is a population density-dependent regulatory system in bacteria that couples gene expression to cell density through accumulation of diffusible signaling molecules. Pectobacteria are causal agents of soft rot disease in a range of economically important crops. They rely on QS to coordinate their main virulence factor, production of plant cell wall degrading enzymes (PCWDEs). Plants have evolved an array of antimicrobial compounds to anticipate and cope with pathogens, of which essential oils (EOs) are widely recognized. Here, volatile EOs, carvacrol and eugenol, were shown to specifically interfere with QS, the master regulator of virulence in pectobacteria, resulting in strong inhibition of QS genes, biofilm formation and PCWDEs, thereby leading to impaired infection. Accumulation of the signal molecule N-acylhomoserine lactone declined upon treatment with EOs, suggesting direct interaction of EOs with either homoserine lactone synthase (ExpI) or with the regulatory protein (ExpR). Homology models of both proteins were constructed and docking simulations were performed to test the above hypotheses. The resulting binding modes and docking scores of carvacrol and eugenol support potential binding to ExpI/ExpR, with stronger interactions than previously known inhibitors of both proteins. The results demonstrate the potential involvement of phytochemicals in the control of Pectobacterium.

Priming of the Arabidopsis pattern-triggered immunity response upon infection by necrotrophic Pectobacterium carotovorum bacteria.

PubMed

Po-Wen, Chen; Singh, Prashant; Zimmerli, Laurent

2013-01-01

Boosted responsiveness of plant cells to stress at the onset of pathogen- or chemically induced resistance is called priming. The chemical β-aminobutyric acid (BABA) enhances Arabidopsis thaliana resistance to hemibiotrophic bacteria through the priming of the salicylic acid (SA) defence response. Whether BABA increases Arabidopsis resistance to the necrotrophic bacterium Pectobacterium carotovorum ssp. carotovorum (Pcc) is not clear. In this work, we show that treatment with BABA protects Arabidopsis against the soft-rot pathogen Pcc. BABA did not prime the expression of the jasmonate/ethylene-responsive gene PLANT DEFENSIN 1.2 (PDF1.2), the up-regulation of which is usually associated with resistance to necrotrophic pathogens. Expression of the SA marker gene PATHOGENESIS RELATED 1 (PR1) on Pcc infection was primed by BABA treatment, but SA-defective mutants demonstrated a wild-type level of BABA-induced resistance against Pcc. BABA primed the expression of the pattern-triggered immunity (PTI)-responsive genes FLG22-INDUCED RECEPTOR-LIKE KINASE 1 (FRK1), ARABIDOPSIS NON-RACE SPECIFIC DISEASE RESISTANCE GENE (NDR1)/HAIRPIN-INDUCED GENE (HIN1)-LIKE 10 (NHL10) and CYTOCHROME P450, FAMILY 81 (CYP81F2) after inoculation with Pcc or after treatment with purified bacterial microbe-associated molecular patterns, such as flg22 or elf26. PTI-mediated callose deposition was also potentiated in BABA-treated Arabidopsis, and BABA boosted Arabidopsis stomatal immunity to Pcc. BABA treatment primed the PTI response in the SA-defective mutants SA induction deficient 2-1 (sid2-1) and phytoalexin deficient 4-1 (pad4-1). In addition, BABA priming was associated with open chromatin configurations in the promoter region of PTI marker genes. Our data indicate that BABA primes the PTI response upon necrotrophic bacterial infection and suggest a role for the PTI response in BABA-induced resistance. © 2012 THE AUTHORS. MOLECULAR PLANT PATHOLOGY © 2012 BSPP AND BLACKWELL PUBLISHING LTD.

Biocontrol potential of Trichoderma harzianum isolate T-aloe against Sclerotinia sclerotiorum in soybean.

PubMed

Zhang, Fuli; Ge, Honglian; Zhang, Fan; Guo, Ning; Wang, Yucheng; Chen, Long; Ji, Xiue; Li, Chengwei

2016-03-01

Sclerotinia stem rot, caused by Sclerotinia sclerotiorum (Lib.) de Bary is a major disease of soybean (Glycine max (L.) Merr.). At present, we revealed the three-way interaction between Trichoderma harzianum T-aloe, pathogen S. sclerotiorum and soybean plants in order to demonstrate biocontrol mechanism and evaluate biocontrol potential of T-aloe against S. sclerotiorum in soybean. In our experiments, T-aloe inhibited the growth of S. sclerotiorum with an efficiency of 56.3% in dual culture tests. T-aloe hyphae grew in parallel or intertwined with S. sclerotiorum hyphae and produced hooked contact branches, indicating mycoparasitism. Plate tests showed that T-aloe culture filtrate inhibited S. sclerotiorum growth with an inhibition efficiency of 51.2% and sclerotia production. T-aloe pretreatment showed growth-promoting effect on soybean plants. The activities of peroxidase, superoxide dismutase, and catalase increased, and the hydrogen peroxide (H2O2) as well as the superoxide radical (O2(-)) content in soybean leaves decreased after T-aloe pretreatment in response to S. sclerotiorum pathogen challenge. T-aloe treatment diminished damage caused by pathogen stress on soybean leaf cell membrane, and increased chlorophyll as well as total phenol contents. The defense-related genes PR1, PR2, and PR3 were expressed in the leaves of T-aloe-treated plants. In summary, T-aloe displayed biocontrol potential against S. sclerotiorum. This is the first report of unraveling biocontrol potential of Trichoderma Spp. to soybean sclerotinia stem rot from the three-way interaction between the biocontrol agent, pathogen S. sclerotiorum and soybean plants. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Integrated management of foot rot of lentil using biocontrol agents under field condition.

PubMed

Hannan, M A; Hasan, M M; Hossain, I; Rahman, S M E; Ismail, Alhazmi Mohammed; Oh, Deog-Hwan

2012-07-01

The efficacy of cowdung, Bangladesh Institute of Nuclear Agriculture (BINA)-biofertilizer, and Bangladesh Agricultural University (BAU)-biofungicide, alone or in combination, was evaluated for controlling foot rot disease of lentil. The results exhibited that BINA-biofertilizer and BAUbiofungicide (peat soil-based Rhizobium leguminosarum and black gram bran-based Trichoderma harzianum) are compatible and have combined effects in controlling the pathogenic fungi Fusarium oxysporum and Sclerotium rolfsii, which cause the root rot of lentil. Cowdung mixing with soil (at 5 t/ha) during final land preparation and seed coating with BINA-biofertilizer and BAU-biofungicide (at 2.5% of seed weight) before sowing recorded 81.50% field emergence of lentil, which showed up to 19.85% higher field emergence over the control. Post-emergence deaths of plants due to foot rot disease were significantly reduced after combined seed treatment with BINA-biofertilizer and BAU-biofungicide. Among the treatments used, only BAU-biofungicide as the seed treating agent resulted in higher plant stand (84.82%). Use of BINA-biofertilizer and BAU-biofungicide as seed treating biocontrol agents and application of cowdung in the soil as an organic source of nutrient resulted in higher shoot and root lengths, and dry shoot and root weights of lentil. BINA-biofertilizer significantly increased the number of nodules per plant and nodules weight of lentil. Seeds treating with BAUbiofungicide and BINA-biofertilizer and soil amendment with cowdung increased the biomass production of lentil up to 75.56% over the control.

Bacterial Diseases of Bananas and Enset: Current State of Knowledge and Integrated Approaches Toward Sustainable Management

PubMed Central

Blomme, Guy; Dita, Miguel; Jacobsen, Kim Sarah; Pérez Vicente, Luis; Molina, Agustin; Ocimati, Walter; Poussier, Stephane; Prior, Philippe

2017-01-01

Bacterial diseases of bananas and enset have not received, until recently, an equal amount of attention compared to other major threats to banana production such as the fungal diseases black leaf streak (Mycosphaerella fijiensis) and Fusarium wilt (Fusarium oxysporum f. sp. cubense). However, bacteria cause significant impacts on bananas globally and management practices are not always well known or adopted by farmers. Bacterial diseases in bananas and enset can be divided into three groups: (1) Ralstonia-associated diseases (Moko/Bugtok disease caused by Ralstonia solanacearum and banana blood disease caused by R. syzygii subsp. celebesensis); (2) Xanthomonas wilt of banana and enset, caused by Xanthomonas campestris pv. musacearum and (3) Erwinia-associated diseases (bacterial head rot or tip-over disease Erwinia carotovora ssp. carotovora and E. chrysanthemi), bacterial rhizome and pseudostem wet rot (Dickeya paradisiaca formerly E. chrysanthemi pv. paradisiaca). Other bacterial diseases of less widespread importance include: bacterial wilt of abaca, Javanese vascular wilt and bacterial fingertip rot (probably caused by Ralstonia spp., unconfirmed). This review describes global distribution, symptoms, pathogenic diversity, epidemiology and the state of the art for sustainable disease management of the major bacterial wilts currently affecting banana and enset. PMID:28785275

Identification and characterization of Pestalotiopsis-like fungi related to grapevine diseases in China.

PubMed

Jayawardena, Ruvishika S; Zhang, Wei; Liu, Mei; Maharachchikumbura, Sajeewa S N; Zhou, Ying; Huang, JinBao; Nilthong, Somrudee; Wang, ZhongYue; Li, XingHong; Yan, JiYe; Hyde, Kevin D

2015-05-01

Pestalotiopsis-like fungi are an important plant pathogenic genus causing postharvest fruit rot and trunk diseases in grapevine in many countries. Pestalotiopsis-like fungi diseases were studied in vineyards in nine provinces across China. Multi-gene (ITS, β-tubulin and tef1) analysis coupled with morphology showed that a Neopestalotiopsis sp. and Pestalotiopsis trachicarpicola are associated in causing grapevine fruit rot and trunk diseases in China. Pestalotiopsis trachicarpicola is reported as the causative agent of grapevine diseases in the world for the first time. Neopestalotiopsis sp. caused significantly longer lesions than the other taxon present. This study represents the first attempt to identify and characterize the Pestalotiopsis-like fungi causing grapevine diseases in China using both morphological and molecular approaches. Copyright © 2014 The British Mycological Society. Published by Elsevier Ltd. All rights reserved.

Screening of bioagents against root rot of mung bean caused by Rhizoctonia solani.

PubMed

Singh, Surender; Chand, Hari

2006-01-01

A laboratory and green house experiment was carried out on the comparative antagonistic performance of four different bioagents (Aspergillus sp. Gliocladium virens, Trichoderma harzianum and T. viride) isolated from soil against Rhizoctonia solani. Under laboratory conditions, T. harzianum exhibited maximum (75.55%) mycelial growth inhibition of R. solani. This was followed by T. viride, which showed 65.93% mycelial growth inhibition of the pathogen. Gliocladium virens was also found to be effective antagonists, which exhibited 57.77% mycelial growth inhibition. While Aspergillus sp exhibited minimum growth inhibition (45.74%) in comparison to other bioagents. Under green house conditions, T. harzianum gave maximum protection of the disease (72.72%) followed by T. viride, which exhibited 54.54% disease control. However, G. virens and Aspergillus sp were found least effective in controlling root rot of mungbean.

Incidence of Craesus castaneae (Hymenoptera: Tenthredinidae) on Chestnut Seedlings Planted in the Daniel Boone National Forest, Kentucky

Treesearch

Cornelia C. Pinchot; Scott E. Schlarbaum; Arnold M. Saxton; Stacy L. Clark; Callie J. Schweitzer; David R. Smith; Alex. Mangini; Frederick V. Hebard

2011-01-01

American chestnut [Castanea dentate (Marshall) Borkhausen, Fagales: Fagaceae] was a dominant forest tree in the eastern forests of the U.S. until it was eliminated as a canopy tree species by 2 exotic pathogens. Ink disease, a root rot caused by Phytophthora cinnamomi Rands (Pythiales: Pythiaceae), began to destroy chestnut populations on bottomland and poorly-drained...

Forest-Site Planning and Prescription for Control of Annosus Root Disease in Ponderosa Pine and Mixed Conifer Stands

Treesearch

John Nesbitt

1989-01-01

In order to successfully combat pathogens such as annosus root rot, the land manager and pathologist must have periodic dialogue about the pest, its identification, effects, impacts, and cures. The author presents four important topics to structure this dialogue. These are (1) training from the pathologist to the silviculturist or other land manager, (2) site specific...

Ethanol and acetone from Douglas-fir roots stressed by Phellinus sulphurascens infection: Implications for detecting diseased trees and for beetle host selection

Treesearch

Rick G. Kelsey; Gladwin Joseph; Doug Westlind; Walter G. Thies

2016-01-01

Phellinus sulphurascens (previously the Douglas-fir form of Phellinus weirii) is an important native pathogen causing laminated root rot in forests of western North America. Visual crown symptoms, or attacks by bark or ambrosia beetles appear only during advanced stages of the disease with extensive infection in the lower bole...

Identification of the infection route of a Fusarium seed pathogen into nondormant Bromus tectorum seeds

Treesearch

JanaLynn Franke; Brad Geary; Susan E. Meyer

2014-01-01

The genus Fusarium has a wide host range and causes many different forms of plant disease. These include seed rot and seedling blight diseases of cultivated plants. The diseases caused by Fusarium on wild plants are less well-known. In this study, we examined disease development caused by Fusarium sp. n on nondormant seeds of the important rangeland weed Bromus...

PecS is a global regulator of the symptomatic phase in the phytopathogenic bacterium Erwinia chrysanthemi 3937.

PubMed

Hommais, Florence; Oger-Desfeux, Christine; Van Gijsegem, Frédérique; Castang, Sandra; Ligori, Sandrine; Expert, Dominique; Nasser, William; Reverchon, Sylvie

2008-11-01

Pathogenicity of the enterobacterium Erwinia chrysanthemi (Dickeya dadantii), the causative agent of soft-rot disease in many plants, is a complex process involving several factors whose production is subject to temporal regulation during infection. PecS is a transcriptional regulator that controls production of various virulence factors. Here, we used microarray analysis to define the PecS regulon and demonstrated that PecS notably regulates a wide range of genes that could be linked to pathogenicity and to a group of genes concerned with evading host defenses. Among the targets are the genes encoding plant cell wall-degrading enzymes and secretion systems and the genes involved in flagellar biosynthesis, biosurfactant production, and the oxidative stress response, as well as genes encoding toxin-like factors such as NipE and hemolysin-coregulated proteins. In vitro experiments demonstrated that PecS interacts with the regulatory regions of five new targets: an oxidative stress response gene (ahpC), a biosurfactant synthesis gene (rhlA), and genes encoding exported proteins related to other plant-associated bacterial proteins (nipE, virK, and avrL). The pecS mutant provokes symptoms more rapidly and with more efficiency than the wild-type strain, indicating that PecS plays a critical role in the switch from the asymptomatic phase to the symptomatic phase. Based on this, we propose that the temporal regulation of the different groups of genes required for the asymptomatic phase and the symptomatic phase is, in part, the result of a gradual modulation of PecS activity triggered during infection in response to changes in environmental conditions emerging from the interaction between both partners.

PecS Is a Global Regulator of the Symptomatic Phase in the Phytopathogenic Bacterium Erwinia chrysanthemi 3937▿ †

PubMed Central

Hommais, Florence; Oger-Desfeux, Christine; Van Gijsegem, Frédérique; Castang, Sandra; Ligori, Sandrine; Expert, Dominique; Nasser, William; Reverchon, Sylvie

2008-01-01

Pathogenicity of the enterobacterium Erwinia chrysanthemi (Dickeya dadantii), the causative agent of soft-rot disease in many plants, is a complex process involving several factors whose production is subject to temporal regulation during infection. PecS is a transcriptional regulator that controls production of various virulence factors. Here, we used microarray analysis to define the PecS regulon and demonstrated that PecS notably regulates a wide range of genes that could be linked to pathogenicity and to a group of genes concerned with evading host defenses. Among the targets are the genes encoding plant cell wall-degrading enzymes and secretion systems and the genes involved in flagellar biosynthesis, biosurfactant production, and the oxidative stress response, as well as genes encoding toxin-like factors such as NipE and hemolysin-coregulated proteins. In vitro experiments demonstrated that PecS interacts with the regulatory regions of five new targets: an oxidative stress response gene (ahpC), a biosurfactant synthesis gene (rhlA), and genes encoding exported proteins related to other plant-associated bacterial proteins (nipE, virK, and avrL). The pecS mutant provokes symptoms more rapidly and with more efficiency than the wild-type strain, indicating that PecS plays a critical role in the switch from the asymptomatic phase to the symptomatic phase. Based on this, we propose that the temporal regulation of the different groups of genes required for the asymptomatic phase and the symptomatic phase is, in part, the result of a gradual modulation of PecS activity triggered during infection in response to changes in environmental conditions emerging from the interaction between both partners. PMID:18790868

Expression levels of antimicrobial peptide tachyplesin I in transgenic Ornithogalum lines affect the resistance to Pectobacterium infection.

PubMed

Lipsky, Alexander; Joshi, Janak Raj; Carmi, Nir; Yedidia, Iris

2016-11-20

The genus Ornithogalum includes several ornamental species that suffer substantial losses from bacterial soft rot caused by Pectobacteria. The absence of effective control measures for use against soft rot bacteria led to the initiation of a project in which a small antimicrobial peptide from an Asian horseshoe crab, tachyplesin (tpnI), was introduced into two commercial cultivars: O. dubium and O. thyrsoides. Disease severity and bacterial colonization were examined in transgenic lines expressing this peptide. Disease resistance was evaluated in six lines of each species by measuring bacterial proliferation in the plant tissue. Three transgenic lines of each species were subjected to further analysis in which the expression level of the transgene was evaluated using RT-PCR and qRT-PCR. The development of disease symptoms and bacterial colonization of the plant tissue were also examined using GFP-expressing strain of P. carotovorum subsp. brasiliense Pcb3. Confocal-microscopy imaging revealed significantly reduced quantities of bacterial cells in the transgenic plant lines that had been challenged with the bacterium. The results clearly demonstrate that tpnI expression reduces bacterial proliferation, colonization and disease symptom (reduced by 95-100%) in the transgenic plant tissues. The quantity of tpnI transcripts, as measured by qRT-PCR, was negatively correlated with the protection afforded to the plants, as measured by the reduced severity of disease symptoms in the tissue. Copyright © 2016 Elsevier B.V. All rights reserved.

Novel N4-Like Bacteriophages of Pectobacterium atrosepticum.

PubMed

Buttimer, Colin; Hendrix, Hanne; Lucid, Alan; Neve, Horst; Noben, Jean-Paul; Franz, Charles; O'Mahony, Jim; Lavigne, Rob; Coffey, Aidan

2018-05-14

Pectobacterium atrosepticum is an economically important phytopathogen that is responsible for potato blackleg and soft rot, and for which current control strategies are limited. In this study, stem samples of potato crops exhibiting blackleg were taken from three farms in Co. Cork, Ireland, and they were found to be infected with P. atrosepticum . Three closely related bacteriophages (phages) that are specific to this phytopathogen were isolated and characterized, namely vB_PatP_CB1, vB_PatP_CB3, and vB_PatP_CB4 (abbreviated as CB1, CB3, and CB4). Both CB1 and CB3 were determined to infect 12 strains and CB4 10 strains of the 19 strains of P. atrosepticum tested. Morphology, latent periods, burst sizes, and their stability at various temperatures and pHs were also examined. Genome sequencing of the three phages revealed that they shared a minimum nucleotide identity of 93% with each other. Their genomes exhibited an Enquartavirinae genome organization, possessing several conserved proteins that were associated with phages of this group, like the type species Escherichia virus N4. Tandem electrospray ionization-mass spectrometry (ESI-MS/MS) allowed for the identification of ten structural proteins that form the virion of CB1, six that are conserved in phage N4. Biocontrol experiments demonstrated that the phages suppress soft rot formation upon co-inoculation with P. atrosepticum on whole tubers. The results of this study indicate that CB1 related phages could be good candidates for phage-based control.

Overexpression of wheat lipid transfer protein gene TaLTP5 increases resistances to Cochliobolus sativus and Fusarium graminearum in transgenic wheat.

PubMed

Zhu, Xiuliang; Li, Zhao; Xu, Huijun; Zhou, Miaoping; Du, Lipu; Zhang, Zengyan

2012-08-01

The fungus Cochliobolus sativus is the main pathogen of common root rot, a serious soil-borne disease of wheat (Triticum aestivum L.). The fungus Fusarium graminearum is the primary pathogen of Fusarium head blight, a devastating disease of wheat worldwide. In this study, the wheat lipid transfer protein gene, TaLTP5, was cloned and evaluated for its ability to suppress disease development in transgenic wheat. TaLTP5 expression was induced after C. sativus infection. The TaLTP5 expression vector, pA25-TaLTP5, was constructed and bombarded into Chinese wheat variety Yangmai 18. Six TaLTP5 transgenic wheat lines were established and characterized. PCR and Southern blot analyses indicated that the introduced TaLTP5 gene was integrated into the genomes of six transgenic wheat lines by distinct patterns, and heritable. RT-PCR and real-time quantitative RT-PCR revealed that the TaLTP5 gene was over-expressed in the transgenic wheat lines compared to segregants lacking the transgene and wild-type wheat plants. Following challenge with C. sativus or F. graminearum, all six transgenic lines overexpressing TaLTP5 exhibited significantly enhanced resistance to both common root rot and Fusarium head blight compared to the untransformed wheat Yangmai 18.

[Fusarium species associated with basal rot of garlic in North Central Mexico and its pathogenicity].

PubMed

Delgado-Ortiz, Juan C; Ochoa-Fuentes, Yisa M; Cerna-Chávez, Ernesto; Beltrán-Beache, Mariana; Rodríguez-Guerra, Raúl; Aguirre-Uribe, Luis A; Vázquez-Martínez, Otilio

Garlic in Mexico is one of the most profitable vegetable crops, grown in almost 5,451ha; out of which more than 83% are located in Zacatecas, Guanajuato, Sonora, Puebla, Baja California and Aguascalientes. Blossom-end rot caused by Fusarium spp is widely distributed worldwide and has been a limiting factor in onion and garlic production regions, not only in Mexico but also in other countries. The presence of Fusarium oxysporum has been reported in Guanajuato and Aguascalientes. Fusarium culmorum has been reported in onion cultivars of Morelos; and Fusarium proliferatum, Fusarium verticillioides, Fusarium solani and Fusarium acuminatum have been previously reported in Aguascalientes. The goal of this work was identifying the Fusarium species found in Zacatecas, Guanajuato and Aguascalientes, to assess their pathogenicity. Plants with disease symptoms were collected from hereinabove mentioned States. The samples resulted in the identification of: F. oxysporum, F. proliferatum, F. verticillioides, F. solani and F. acuminatum species; out of which Aguascalientes AGS1A (F. oxysporum), AGS1B (F. oxysporum) and AGSY-10 (F. acuminatum) strains showed higher severity under greenhouse conditions. Copyright © 2016 Asociación Argentina de Microbiología. Publicado por Elsevier España, S.L.U. All rights reserved.

Biocontrol ability and action mechanism of food-isolated yeast strains against Botrytis cinerea causing post-harvest bunch rot of table grape.

PubMed

Parafati, Lucia; Vitale, Alessandro; Restuccia, Cristina; Cirvilleri, Gabriella

2015-05-01

Strains belonging to the species Saccharomyces cerevisiae, Wickerhamomyces anomalus, Metschnikowia pulcherrima and Aureobasidium pullulans, isolated from different food sources, were tested in vitro as biocontrol agents (BCAs) against the post-harvest pathogenic mold Botrytis cinerea. All yeast strains demonstrated antifungal activity at different levels depending on species and medium. Killer strains of W. anomalus and S. cerevisiae showed the highest biocontrol in vitro activity, as demonstrated by largest inhibition halos. The competition for iron and the ability to form biofilm and to colonize fruit wounds were hypothesized as the main action mechanisms for M. pulcherrima. The production of hydrolytic enzymes and the ability to colonize the wounds were the most important mechanisms for biocontrol activity in A. pullulans and W. anomalus, which also showed high ability to form biofilm. The production of volatile organic compounds (VOCs) with in vitro and in vivo inhibitory effect on pathogen growth was observed for the species W. anomalus, S. cerevisiae and M. pulcherrima. Our study clearly indicates that multiple modes of action may explain as M. pulcherrima provide excellent control of postharvest botrytis bunch rot of grape. Copyright © 2014 Elsevier Ltd. All rights reserved.

Differential induction of chitinase in Piper colubrinum in response to inoculation with Phytophthora capsici, the cause of foot rot in black pepper

PubMed Central

Sandeep Varma, R.; Johnson George, K.; Balaji, S.; Parthasarathy, V.A.

2009-01-01

Plant chitinases have been of particular interest since they are known to be induced upon pathogen invasion. Inoculation of Piper colubrinum leaves with the foot rot fungus, Phytophthora capsici leads to increase in chitinase activity. A marked increase in chitinase activity in the inoculated leaves was observed, with the maximum activity after 60 h of inoculation and gradually decreased thereafter. Older leaves showed more chitinase activity than young leaves. The level of chitinase in black pepper (Piper nigrum L.) upon inoculation was found to be substantially high when compared to P. colubrinum. RT–PCR using chitinase specific primers revealed differential accumulation of mRNA in P. colubrinum leaves inoculated with P. capsici. However, hyphal extension assays revealed no obvious differences in the ability of the protein extracts to inhibit growth of P. capsici in vitro. PMID:23961037

Comparative Analysis of 35 Basidiomycete Genomes Reveals Diversity and Uniqueness of the Phylum

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

Riley, Robert; Salamov, Asaf; Otillar, Robert

Fungi of the phylum Basidiomycota (basidiomycetes), make up some 37percent of the described fungi, and are important in forestry, agriculture, medicine, and bioenergy. This diverse phylum includes symbionts, pathogens, and saprobes including wood decaying fungi. To better understand the diversity of this phylum we compared the genomes of 35 basidiomycete fungi including 6 newly sequenced genomes. The genomes of basidiomycetes span extremes of genome size, gene number, and repeat content. A phylogenetic tree of Basidiomycota was generated using the Phyldog software, which uses all available protein sequence data to simultaneously infer gene and species trees. Analysis of core genes revealsmore » that some 48percent of basidiomycete proteins are unique to the phylum with nearly half of those (22percent) comprising proteins found in only one organism. Phylogenetic patterns of plant biomass-degrading genes suggest a continuum rather than a sharp dichotomy between the white rot and brown rot modes of wood decay among the members of Agaricomycotina subphylum. There is a correlation of the profile of certain gene families to nutritional mode in Agaricomycotina. Based on phylogenetically-informed PCA analysis of such profiles, we predict that that Botryobasidium botryosum and Jaapia argillacea have properties similar to white rot species, although neither has liginolytic class II fungal peroxidases. Furthermore, we find that both fungi exhibit wood decay with white rot-like characteristics in growth assays. Analysis of the rate of discovery of proteins with no or few homologs suggests the high value of continued sequencing of basidiomycete fungi.« less

Endophytic Bacteria Improve Plant Growth, Symbiotic Performance of Chickpea (Cicer arietinum L.) and Induce Suppression of Root Rot Caused by Fusarium solani under Salt Stress.

PubMed

Egamberdieva, Dilfuza; Wirth, Stephan J; Shurigin, Vyacheslav V; Hashem, Abeer; Abd Allah, Elsayed F

2017-01-01

Salinity causes disturbance in symbiotic performance of plants, and increases susceptibility of plants to soil-borne pathogens. Endophytic bacteria are an essential determinant of cross-tolerance to biotic and abiotic stresses in plants. The aim of this study was to isolate non-rhizobial endophytic bacteria from the root nodules of chickpea ( Cicer arietinum L.), and to assess their ability to improve plant growth and symbiotic performance, and to control root rot in chickpea under saline soil conditions. A total of 40 bacterial isolates from internal root tissues of chickpea grown in salinated soil were isolated. Four bacterial isolates, namely Bacillus cereus NUU1 , Achromobacter xylosoxidans NUU2, Bacillus thuringiensis NUU3, and Bacillus subtilis NUU4 colonizing root tissue demonstrated plant beneficial traits and/or antagonistic activity against F. solani and thus were characterized in more detail. The strain B. subtilis NUU4 proved significant plant growth promotion capabilities, improved symbiotic performance of host plant with rhizobia, and promoted yield under saline soil as compared to untreated control plants under field conditions. A combined inoculation of chickpea with M. ciceri IC53 and B. subtilis NUU4 decreased H 2 O 2 concentrations and increased proline contents compared to the un-inoculated plants indicating an alleviation of adverse effects of salt stress. Furthermore, the bacterial isolate was capable to reduce the infection rate of root rot in chickpea caused by F. solani . This is the first report of F. solani causing root rot of chickpea in a salinated soil of Uzbekistan. Our findings demonstrated that the endophytic B. subtilis strain NUU4 provides high potentials as a stimulator for plant growth and as biological control agent of chickpea root rot under saline soil conditions. These multiple relationships could provide promising practical approaches to increase the productivity of legumes under salt stress.

Endophytic Bacteria Improve Plant Growth, Symbiotic Performance of Chickpea (Cicer arietinum L.) and Induce Suppression of Root Rot Caused by Fusarium solani under Salt Stress

PubMed Central

Egamberdieva, Dilfuza; Wirth, Stephan J.; Shurigin, Vyacheslav V.; Hashem, Abeer; Abd_Allah, Elsayed F.

2017-01-01

Salinity causes disturbance in symbiotic performance of plants, and increases susceptibility of plants to soil-borne pathogens. Endophytic bacteria are an essential determinant of cross-tolerance to biotic and abiotic stresses in plants. The aim of this study was to isolate non–rhizobial endophytic bacteria from the root nodules of chickpea (Cicer arietinum L.), and to assess their ability to improve plant growth and symbiotic performance, and to control root rot in chickpea under saline soil conditions. A total of 40 bacterial isolates from internal root tissues of chickpea grown in salinated soil were isolated. Four bacterial isolates, namely Bacillus cereus NUU1, Achromobacter xylosoxidans NUU2, Bacillus thuringiensis NUU3, and Bacillus subtilis NUU4 colonizing root tissue demonstrated plant beneficial traits and/or antagonistic activity against F. solani and thus were characterized in more detail. The strain B. subtilis NUU4 proved significant plant growth promotion capabilities, improved symbiotic performance of host plant with rhizobia, and promoted yield under saline soil as compared to untreated control plants under field conditions. A combined inoculation of chickpea with M. ciceri IC53 and B. subtilis NUU4 decreased H2O2 concentrations and increased proline contents compared to the un-inoculated plants indicating an alleviation of adverse effects of salt stress. Furthermore, the bacterial isolate was capable to reduce the infection rate of root rot in chickpea caused by F. solani. This is the first report of F. solani causing root rot of chickpea in a salinated soil of Uzbekistan. Our findings demonstrated that the endophytic B. subtilis strain NUU4 provides high potentials as a stimulator for plant growth and as biological control agent of chickpea root rot under saline soil conditions. These multiple relationships could provide promising practical approaches to increase the productivity of legumes under salt stress. PMID:29033922

PAMPs, PRRs, effectors and R-genes associated with citrus-pathogen interactions.

PubMed

Dalio, Ronaldo J D; Magalhães, Diogo M; Rodrigues, Carolina M; Arena, Gabriella D; Oliveira, Tiago S; Souza-Neto, Reinaldo R; Picchi, Simone C; Martins, Paula M M; Santos, Paulo J C; Maximo, Heros J; Pacheco, Inaiara S; De Souza, Alessandra A; Machado, Marcos A

2017-03-01

Recent application of molecular-based technologies has considerably advanced our understanding of complex processes in plant-pathogen interactions and their key components such as PAMPs, PRRs, effectors and R-genes. To develop novel control strategies for disease prevention in citrus, it is essential to expand and consolidate our knowledge of the molecular interaction of citrus plants with their pathogens. This review provides an overview of our understanding of citrus plant immunity, focusing on the molecular mechanisms involved in the interactions with viruses, bacteria, fungi, oomycetes and vectors related to the following diseases: tristeza, psorosis, citrus variegated chlorosis, citrus canker, huanglongbing, brown spot, post-bloom, anthracnose, gummosis and citrus root rot. © The Author 2017. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com

Severe soft tissue infection of the lower extremity caused by Haemophilus influenzae (serotype f, biotype II) in an adult patient.

PubMed

Hagiya, Hideharu; Murase, Tomoko; Naito, Hiromichi; Hagioka, Shingo; Morimoto, Naoki

2012-01-01

The infection caused by non-b-type Haemophilus influenzae has been increasing in this Hib (H.influenzae serotype b) vaccination era. H.influenzae serotype f (Hif) is considered as one of those emerging pathogens. In general, H.influenzae is a common pathogen of such as pneumonia, otitis media, and meningitis, but is rare in soft tissue infection, especially at the extremity. We report a rare case of severe soft tissue infection caused by Hif which occurred at the lower extremity of immunocompetent adult patient.

Comparative secretome analysis of Colletotrichum falcatum identifies a cerato-platanin protein (EPL1) as a potential pathogen-associated molecular pattern (PAMP) inducing systemic resistance in sugarcane.

PubMed

Ashwin, N M R; Barnabas, Leonard; Ramesh Sundar, Amalraj; Malathi, Palaniyandi; Viswanathan, Rasappa; Masi, Antonio; Agrawal, Ganesh Kumar; Rakwal, Randeep

2017-10-03

Colletotrichum falcatum, an intriguing hemibiotrophic fungal pathogen causes red rot, a devastating disease of sugarcane. Repeated in vitro subculturing of C. falcatum under dark condition alters morphology and reduces virulence of the culture. Hitherto, no information is available on this phenomenon at molecular level. In this study, the in vitro secretome of C. falcatum cultured under light and dark conditions was analyzed using 2-DE coupled with MALDI TOF/TOF MS. Comparative analysis identified nine differentially abundant proteins. Among them, seven proteins were less abundant in the dark-cultured C. falcatum, wherein only two protein species of a cerato-platanin protein called EPL1 (eliciting plant response-like protein) were found to be highly abundant. Transcriptional expression of candidate high abundant proteins was profiled during host-pathogen interaction using qRT-PCR. Comprehensively, this comparative secretome analysis identified five putative effectors, two pathogenicity-related proteins and one pathogen-associated molecular pattern (PAMP) of C. falcatum. Functional characterization of three distinct domains of the PAMP (EPL1) showed that the major cerato-platanin domain (EPL1∆N1-92) is exclusively essential for inducing defense and hypersensitive response (HR) in sugarcane and tobacco, respectively. Further, priming with EPL1∆N1-92 protein induced systemic resistance and significantly suppressed the red rot severity in sugarcane. Being the first secretomic investigation of C. falcatum, this study has identified five potential effectors, two pathogenicity-related proteins and a PAMP. Although many reports have highlighted the influence of light on pathogenicity, this study has established a direct link between light and expression of effectors, for the first time. This study has presented the influence of a novel N-terminal domain of EPL1 in physical and biological properties and established the functional role of major cerato-platanin domain of EPL1 as a potential elicitor inducing systemic resistance in sugarcane. Comprehensively, the study has identified proteins that putatively contribute to virulence of C. falcatum and for the first time, demonstrated the potential role of EPL1 in inducing PAMP-triggered immunity (PTI) in sugarcane. Copyright © 2017 Elsevier B.V. All rights reserved.

Preoperative evaluation of micro-organisms in non-operated cleft in soft palate: impact on use of antibiotics.

PubMed

Roode, G J; Bütow, K-W; Naidoo, S

2017-02-01

To identify the pathogenic micro-organisms that had colonised preoperatively in clefts in the soft palate and oro-nasopharynx, we retrospectively studied the preoperative microbiological profiles of 200 infants who had had primary repair of all types of cleft in the soft palate. Data from a private practice that specialises in the repair of facial clefts were extracted randomly from patients' files. We analysed the results of the culture of preoperative swabs taken from clefts in the soft palate and oro-nasopharynx, and the resistance profile of organisms towards various antibiotics. A total of 23 different pathogenic micro-organisms were isolated from 115 (57%) of the sample. Klebsiella pneumoniae most commonly colonised clefts in the lip, alveolus, and palate. This was considerably higher than in other groups. The second most common micro-organism was Staphylococcus aureus, which was found most often in patients with isolated clefts in the hard palate. Those with complete cleft lip and palate presented with more pathogenic micro-organisms in preoperative cultures than those with other types of cleft. We need to find a way to control pathogenic micro-organisms in the oral and oro-nasopharyngeal region preoperatively to limit postoperative complications. Copyright © 2016 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

Global regulators ExpA (GacA) and KdgR modulate extracellular enzyme gene expression through the RsmA-rsmB system in Erwinia carotovora subsp. carotovora.

PubMed

Hyytiäinen, H; Montesano, M; Palva, E T

2001-08-01

The production of the main virulence determinants, the extracellular plant cell wall-degrading enzymes, and hence virulence of Erwinia carotovora subsp. carotovora is controlled by a complex regulatory network. One of the global regulators, the response regulator ExpA, a GacA homolog, is required for transcriptional activation of the extracellular enzyme genes of this soft-rot pathogen. To elucidate the mechanism of ExpA control as well as interactions with other regulatory systems, we isolated second-site transposon mutants that would suppress the enzyme-negative phenotype of an expA (gacA) mutant. Inactivation of kdgR resulted in partial restoration of extracellular enzyme production and virulence to the expA mutant, suggesting an interaction between the two regulatory pathways. This interaction was mediated by the RsmA-rsmB system. Northern analysis was used to show that the regulatory rsmB RNA was under positive control of ExpA. Conversely, the expression of rsmA encoding a global repressor was under negative control of ExpA and positive control of KdgR. This study indicates a central role for the RsmA-rsmB regulatory system during pathogenesis, integrating signals from the ExpA (GacA) and KdgR global regulators of extracellular enzyme production in E. carotovora subsp. carotovora.

Microsatellite markers used for genome-wide association mapping of partial resistance to Sclerotinia sclerotiorum in a world collection of Brassica napus.

PubMed

Gyawali, Sanjaya; Harrington, Myrtle; Durkin, Jonathan; Horner, Kyla; Parkin, Isobel A P; Hegedus, Dwayne D; Bekkaoui, Diana; Buchwaldt, Lone

The fungal pathogen Sclerotinia sclerotiorum causes stem rot of oilseed rape ( Brassica napus ) worldwide. In preparation for genome-wide association mapping (GWAM) of sclerotinia resistance in B. napus , 152 accessions from diverse geographical regions were screened with a single Canadian isolate, #321. Plants were inoculated by attaching mycelium plugs to the main stem at full flower. Lesion lengths measured 7, 14 and 21 days after inoculation were used to calculate the area under the disease progress curve (AUDPC). Depth of penetration was noted and used to calculate percent soft and collapsed lesions (% s + c). The two disease traits were highly correlated ( r  = 0.93). Partially resistant accessions (AUDPC <7 and % s + c <2) were identified primarily from South Korea and Japan with a few from Pakistan, China and Europe. Genotyping of accessions with 84 simple sequence repeat markers provided 690 polymorphic loci for GWAM. The general linear model in TASSEL best fitted the data when adjusted for population structure (STRUCTURE), GLM + Q. After correction for positive false discovery rate, 34 loci were significantly associated with both disease traits of which 21 alleles contributed to resistance, while the remaining enhanced susceptibility. The phenotypic variation explained by the loci ranged from 6 to 25 %. Five loci mapped to published quantitative trait loci conferring sclerotinia resistance in Chinese lines.

Adaptation to new nutritional environments: larval performance, foraging decisions, and adult oviposition choices in Drosophila suzukii.

PubMed

Silva-Soares, Nuno F; Nogueira-Alves, A; Beldade, P; Mirth, Christen Kerry

2017-06-07

Understanding how species adapt to new niches is a central issue in evolutionary ecology. Nutrition is vital for the survival of all organisms and impacts species fitness and distribution. While most Drosophila species exploit rotting plant parts, some species have diversified to use ripe fruit, allowing earlier colonization. The decomposition of plant material is facilitated by yeast colonization and proliferation. These yeasts serve as the main protein source for Drosophila larvae. This dynamic rotting process entails changes in the nutritional composition of the food and other properties, and animals feeding on material at different stages of decay are expected to have behavioural and nutritional adaptations. We compared larval performance, feeding behaviour and adult oviposition site choice between the ripe fruit colonizer and invasive pest Drosophila suzukii, and a closely-related rotting fruit colonizer, Drosophila biarmipes. Through the manipulation of protein:carbohydrate ratios in artificial diets, we found that D. suzukii larvae perform better at lower protein concentrations and consume less protein rich diets relative to D. biarmipes. For adult oviposition, these species differed in preference for substrate hardness, but not for the substrate nutritional composition. Our findings highlight that rather than being an exclusive specialist on ripe fruit, D. suzukii's adaptation to use ripening fruit allow it to colonize a wider range of food substrates than D. biarmipes, which is limited to soft foods with higher protein concentrations. Our results underscore the importance of nutritional performance and feeding behaviours in the colonization of new food niches.

Impact of the Regulators SigB, Rot, SarA and sarS on the Toxic Shock Tst Promoter and TSST-1 Expression in Staphylococcus aureus

PubMed Central

Villanueva, Maite; Renzoni, Adriana; Monod, Antoinette; Barras, Christine; Rodriguez, Natalia; Kelley, William L.

2015-01-01

Staphylococcus aureus is an important pathogen manifesting virulence through diverse disease forms, ranging from acute skin infections to life-threatening bacteremia or systemic toxic shock syndromes. In the latter case, the prototypical superantigen is TSST-1 (Toxic Shock Syndrome Toxin 1), encoded by tst(H), and carried on a mobile genetic element that is not present in all S. aureus strains. Transcriptional regulation of tst is only partially understood. In this study, we dissected the role of sarA, sarS (sarH1), RNAIII, rot, and the alternative stress sigma factor sigB (σB). By examining tst promoter regulation predominantly in the context of its native sequence within the SaPI1 pathogenicity island of strain RN4282, we discovered that σB emerged as a particularly important tst regulator. We did not detect a consensus σB site within the tst promoter, and thus the effect of σB is likely indirect. We found that σB strongly repressed the expression of the toxin via at least two distinct regulatory pathways dependent upon sarA and agr. Furthermore rot, a member of SarA family, was shown to repress tst expression when overexpressed, although its deletion had no consistent measurable effect. We could not find any detectable effect of sarS, either by deletion or overexpression, suggesting that this regulator plays a minimal role in TSST-1 expression except when combined with disruption of sarA. Collectively, our results extend our understanding of complex multifactorial regulation of tst, revealing several layers of negative regulation. In addition to environmental stimuli thought to impact TSST-1 production, these findings support a model whereby sporadic mutation in a few key negative regulators can profoundly affect and enhance TSST-1 expression. PMID:26275216

Evaluating food additives as antifungal agents against Monilinia fructicola in vitro and in hydroxypropyl methylcellulose-lipid composite edible coatings for plums.

PubMed

Karaca, Hakan; Pérez-Gago, María B; Taberner, Verònica; Palou, Lluís

2014-06-02

Common food preservative agents were evaluated in in vitro tests for their antifungal activity against Monilinia fructicola, the most economically important pathogen causing postharvest disease of stone fruits. Radial mycelial growth was measured in Petri dishes of PDA amended with three different concentrations of the agents (0.01-0.2%, v/v) after 7 days of incubation at 25 °C. Thirteen out of fifteen agents tested completely inhibited the radial growth of the fungus at various concentrations. Among them, ammonium carbonate, ammonium bicarbonate and sodium bicarbonate were the most effective while sodium acetate and sodium formate were the least effective. The effective agents and concentrations were tested as ingredients of hydroxypropyl methylcellulose (HPMC)-lipid edible coatings against brown rot disease on plums previously inoculated with M. fructicola (curative activity). 'Friar' and 'Larry Ann' plums were inoculated with the pathogen, coated with stable edible coatings about 24h later, and incubated at 20 °C and 90% RH. Disease incidence (%) and severity (lesion diameter) were determined after 4, 6, and 8 days of incubation and the 'area under the disease progress stairs' (AUDPS) was calculated. Coatings containing bicarbonates and parabens significantly reduced brown rot incidence in plums, but potassium sorbate, used at 1.0% in the coating formulation, was the most effective agent with a reduction rate of 28.6%. All the tested coatings reduced disease severity to some extent, but coatings containing 0.1% sodium methylparaben or sodium ethylparaben or 0.2% ammonium carbonate or ammonium bicarbonate were superior to the rest, with reduction rates of 45-50%. Overall, the results showed that most of the agents tested in this study had significant antimicrobial activity against M. fructicola and the application of selected antifungal edible coatings is a promising alternative for the control of postharvest brown rot in plums. Copyright © 2014 Elsevier B.V. All rights reserved.

A Chitosan Coating Containing Essential Oil from Origanum vulgare L. to Control Postharvest Mold Infections and Keep the Quality of Cherry Tomato Fruit

PubMed Central

Barreto, Tainá A.; Andrade, Sonalle C. A.; Maciel, Janeeyre F.; Arcanjo, Narciza M. O.; Madruga, Marta S.; Meireles, Bruno; Cordeiro, Ângela M. T.; Souza, Evandro L.; Magnani, Marciane

2016-01-01

The efficacy of an edible chitosan coating (CHI; 4 mg/mL) and Origanum vulgare L. essential oil (OVEO; 1.25 μL/mL) for maintaining the quality of cherry tomato fruit during storage at room (25°C; 12 days) and cold (12°C; 24 days) temperatures was assessed. CHI and OVEO in combination showed in vitro fungicidal effects against R. stolonifer and Aspergillus niger. CHI-OVEO coating reduced the incidence of black mold and soft rot caused by these fungi in artificially contaminated cherry tomato fruit during storage at both temperatures. CHI-OVEO coating delayed the appearance of the first visible signs of black mold and soft rot in artificially contaminated cherry tomato fruit stored at room temperature by 6 days and by more than 9 days in those stored at cold temperature. At the end of storage at room and cold temperature fruit coated with CHI-OVEO showed higher firmness (>2 N/mm) and lower weight loss (>2%) compared to uncoated tomato fruit. CHI-OVEO coating delayed the decrease of lycopene, ascorbic citric acid, glucose and fructose during the storage time assessed at room or cold temperatures. The increase of catechin, myricetin, caffeic and syringic acids was higher (1–9 mg/g) in cherry tomato fruit coated with CHI-OVEO compared to uncoated fruit during the storage at both temperatures studied. CHI-OVEO coating is a feasible treatment for maintaining the storage quality of cherry tomato fruit. PMID:27877156

Caenorhabditis elegans star formation and negative chemotaxis induced by infection with corynebacteria.

PubMed

Antunes, Camila Azevedo; Clark, Laura; Wanuske, Marie-Therès; Hacker, Elena; Ott, Lisa; Simpson-Louredo, Liliane; de Luna, Maria das Gracas; Hirata, Raphael; Mattos-Guaraldi, Ana Luíza; Hodgkin, Jonathan; Burkovski, Andreas

2016-01-01

Caenorhabditis elegans is one of the major model systems in biology based on advantageous properties such as short life span, transparency, genetic tractability and ease of culture using an Escherichia coli diet. In its natural habitat, compost and rotting plant material, this nematode lives on bacteria. However, C. elegans is a predator of bacteria, but can also be infected by nematopathogenic coryneform bacteria such Microbacterium and Leucobacter species, which display intriguing and diverse modes of pathogenicity. Depending on the nematode pathogen, aggregates of worms, termed worm-stars, can be formed, or severe rectal swelling, so-called Dar formation, can be induced. Using the human and animal pathogens Corynebacterium diphtheriae and Corynebacterium ulcerans as well as the non-pathogenic species Corynebacterium glutamicum, we show that these coryneform bacteria can also induce star formation slowly in worms, as well as a severe tail-swelling phenotype. While C. glutamicum had a significant, but minor influence on survival of C. elegans, nematodes were killed after infection with C. diphtheriae and C. ulcerans. The two pathogenic species were avoided by the nematodes and induced aversive learning in C. elegans.

Identification, characterization and mycotoxigenic ability of Alternaria spp. causing core rot of apple fruit in Greece.

PubMed

Ntasiou, Panagiota; Myresiotis, Charalampos; Konstantinou, Sotiris; Papadopoulou-Mourkidou, Euphemia; Karaoglanidis, George S

2015-03-16

Alternaria core rot is a major postharvest disease of apple fruit in several countries of the world, including Greece. The study was conducted aiming to identify the disease causal agents at species level, investigate the aggressiveness of Alternaria spp. isolates and the susceptibility of different apple varieties and determine the mycotoxigenic potential of Alternaria spp. isolates from apple fruit. Seventy-five Alternaria spp. isolates obtained from apple fruit showing core rot symptoms were identified as either Alternaria tenuissima or Alternaria arborescens at frequencies of 89.3 and 11.7%, respectively, based on the sequence of endopolygalacturonase (EndoPG) gene. Artificial inoculations of fruit of 4 different varieties (Fuji, Golden Delicious, Granny Smith and Red Delicious) and incubation at two different temperatures (2 and 25°C) showed that fruit of Fuji variety were the most susceptible and fruit of Golden Delicious the most resistant to both pathogens. In addition, the production of 3 mycotoxins, alternariol (AOH), alternariol monomethyl ether (AME) and tentoxin (TEN) was investigated in 30 isolates of both species. Mycotoxin determination was conducted both in vitro, on artificial nutrient medium and in vivo on artificially inoculated apple fruit, using a high performance liquid chromatography with diode array detector (HPLC-DAD). The results showed that most of the isolates of both species were able to produce all the 3 metabolites both in vivo and in vitro. On apple fruit A. tenuissima isolates produced more AOH than A. arborescens isolates, whereas the latter produced more TEN than the former. Such results indicate that Alternaria core rot represents a major threat of apple fruit production not only due to quantitative yield losses but also for qualitative deterioration of apple by-products. Copyright © 2014 Elsevier B.V. All rights reserved.

Potential of UVC germicidal irradiation in suppressing crown rot disease, retaining postharvest quality and antioxidant capacity of Musa AAA "Berangan" during fruit ripening.

PubMed

S Mohamed, Nuratika Tamimi; Ding, Phebe; Kadir, Jugah; M Ghazali, Hasanah

2017-09-01

Crown rot caused by fungal pathogen is the most prevalent postharvest disease in banana fruit that results significant economic losses during transportation, storage, and ripening period. Antifungal effects of ultraviolet C (UVC) irradiation at doses varied from 0.01 to 0.30 kJ m -2 were investigated in controlling postharvest crown rot disease, maintenance of fruit quality, and the effects on antioxidant capacity of Berangan banana fruit during ripening days at 25 ± 2°C and 85% RH. Fruits irradiated with 0.30 kJ m -2 exhibited the highest (i.e., 62.51%) reduction in disease severity. However, the application of UVC at all doses caused significant browning damages on fruit peel except the dose of 0.01 kJ m -2 . This dose synergistically reduced 46.25% development of postharvest crown and did not give adverse effects on respiration rate, ethylene production, weight loss, firmness, color changes, soluble solids concentration, titratable acidity, and pH in banana as compared to the other treatments and control. Meanwhile, the dose also enhanced a significant higher level of total phenolic content, FRAP, and DPPH values than in control fruits indicating the beneficial impact of UVC in fruit nutritional quality. The results of scanning electron micrographs confirmed that UVC irradiation retarded the losses of wall compartments, thereby maintained the cell wall integrity in the crown tissue of banana fruit. The results suggest that using 0.01 kJ m -2 UVC irradiation dose as postharvest physical treatment, the crown rot disease has potential to be controlled effectively together with maintaining quality and antioxidant of banana fruit.

First report of the root-rot pathogen, Armillaria gallica, on koa (Acacia koa) and 'Ohi'a lehua (Metrosideros polymorpha) on the island of Kaua'i, Hawai'i

Treesearch

M. -S. Kim; N. R. Fonseca; R. D. Hauff; P. G. Cannon; John Hanna; Ned Klopfenstein

2017-01-01

Koa (Acacia koa) and 'ohi'a lehua (Metrosideros polymorpha) are the two most dominant native tree species in Hawai‘i. Their populations are continuously decreasing, primarily because of forest disease (Dudley et al. 2007; Keith et al. 2015) and other biotic disturbances. In April 2015, Armillaria rhizomorphs were collected from woody hosts on the...

Evaluation of commercial essential oil samples on the growth of postharvest pathogen Monilinia fructicola (G. Winter) Honey.

PubMed

Lazar-Baker, E E; Hetherington, S D; Ku, V V; Newman, S M

2011-03-01

To assess the effect of several commercial essential oils samples Australian lemon myrtle (Backhousia citriodora), cinnamon bark (Cinnamomum zeylanicum), oregano (Origanum vulgare), thyme oil (Thymus vulgaris), clove bud (Eugenia caryophyllata), valerian (Valeriana officinalis) and Australian tea tree oil (Melaleuca alternifolia) on mycelium growth and spore germination of Monilinia fructicola. The effectiveness of lemon myrtle essential oil as a fumigant for the control of brown rot in nectarines was evaluated. Monilinia fructicola exhibited a different level of sensitivity to each tested essential oil with results suggesting that the essential oils provide excellent control of the pathogen with respect to mycelium growth and spore germination at very low concentrations, whereas for others higher concentrations are needed to reduce significant fungal growth. In vivo application of lemon myrtle essential oil effectively reduced the incidence of M. fructicola on noninoculated fruit. Fumigation of nectarines following inoculation did not reduce the incidence of brown rot in comparison with the inoculated control treatment. No evidence of phytotoxicity on the fruit was recorded. Lemon myrtle essential oil exhibited the strongest antifungal activity against M. fructicola, in vitro and to a lesser extent, under in vivo conditions. The results demonstrate that lemon myrtle essential oil, in particular, has potential as an antifungal agent to control M. fructicola. © 2011 NSW Industry & Investment, Australia. Letters in Applied Microbiology © 2011 The Society for Applied Microbiology.

Highly selective trapping of enteropathogenic E. coli on Fabry-Pérot sensor mirrors.

PubMed

Ivanova, Elena P; Truong, Vi Khanh; Gervinskas, Gediminas; Mitik-Dineva, Natasa; Day, Daniel; Jones, Robert T; Crawford, Russell J; Juodkazis, Saulius

2012-05-15

Untreated recycled water, such as sewage and graywater, will almost always contain a wide range of agents that are likely to present risks to human health, including chemicals and pathogenic microorganisms. The microbial hazards, such as large numbers of enteric pathogens that can cause gastroenteric illness if ingested, are the main cause of concern for human health. The presence of the enteropathogenic Escherichia coli (EPEC) serotype is of particular concern, as this group of bacteria is responsible for causing severe infant and travelers' diarrhea, gastroenteritis and hemolytic uremic syndrome. A biosensing system based on an optical Fabry-Pérot (FP) cavity, capable of directly detecting the presence of EPEC within 5 min, has been developed using a simple micro-thin double-sided adhesive tape and two semi-transparent FP mirror plates. The system utilizes a poly(methyl methacrylate) (PMMA) or glass substrates sputtered by 40-nm-thick gold thin films serving as FP mirrors. Mirrors have been activated using 0.1M mercaptopropionic acid, influencing an immobilization density of the translocated intimin receptor (TIR) of 100 ng/cm(2). The specificity of recognition was confirmed by exposing TIR functionalized surfaces to four taxonomically related and/or distantly related bacterial strains. It was found that the TIR-functionalized surfaces did not show any bacterial capture for these other bacterial strains within a 15 min incubation period. Copyright © 2012 Elsevier B.V. All rights reserved.

Evidence that the Ceratobasidium-like white-thread blight and black rot fungal pathogens from persimmon and tea crops in the Brazilian Atlantic Forest agroecosystem are two distinct phylospecies.

PubMed

Ceresini, Paulo C; Costa-Souza, Elaine; Zala, Marcello; Furtado, Edson L; Souza, Nilton L

2012-04-01

The white-thread blight and black rot (WTBR) caused by basidiomycetous fungi of the genus Ceratobasidium is emerging as an important plant disease in Brazil, particularly for crop species in the Ericales such as persimmon (Diospyros kaki) and tea (Camellia sinensis). However, the species identity of the fungal pathogen associated with either of these hosts is still unclear. In this work, we used sequence variation in the internal transcribed spacer regions, including the 5.8S coding region of rDNA (ITS-5.8S rDNA), to determine the phylogenetic placement of the local white-thread-blight-associated populations of Ceratobasidium sp. from persimmon and tea, in relation to Ceratobasidium species already described world-wide. The two sister populations of Ceratobasidium sp. from persimmon and tea in the Brazilian Atlantic Forest agroecosystem most likely represent distinct species within Ceratobasidium and are also distinct from C. noxium, the etiological agent of the first description of white-thread blight disease that was reported on coffee in India. The intraspecific variation for the two Ceratobasidium sp. populations was also analyzed using three mitochondrial genes (ATP6, nad1 and nad2). As reported for other fungi, variation in nuclear and mitochondrial DNA was incongruent. Despite distinct variability in the ITS-rDNA region these two populations shared similar mitochondrial DNA haplotypes.

Cyclic Lipopeptides of Bacillus amyloliquefaciens subsp. plantarum Colonizing the Lettuce Rhizosphere Enhance Plant Defense Responses Toward the Bottom Rot Pathogen Rhizoctonia solani.

PubMed

Chowdhury, Soumitra Paul; Uhl, Jenny; Grosch, Rita; Alquéres, Sylvia; Pittroff, Sabrina; Dietel, Kristin; Schmitt-Kopplin, Philippe; Borriss, Rainer; Hartmann, Anton

2015-09-01

The commercially available inoculant Bacillus amyloliquefaciens FZB42 is able to considerably reduce lettuce bottom rot caused by Rhizoctonia solani. To understand the interaction between FZB42 and R. solani in the rhizosphere of lettuce, we used an axenic system with lettuce bacterized with FZB42 and inoculated with R. solani. Confocal laser scanning microscopy showed that FZB42 could delay the initial establishment of R. solani on the plants. To show which secondary metabolites of FZB42 are produced under these in-situ conditions, we developed an ultra-high performance liquid chromatography coupled to time of flight mass spectrometry-based method and identified surfactin, fengycin, and bacillomycin D in the lettuce rhizosphere. We hypothesized that lipopeptides and polyketides play a role in enhancing the plant defense responses in addition to the direct antagonistic effect toward R. solani and used a quantitative real-time polymerase chain reaction-based assay for marker genes involved in defense signaling pathways in lettuce. A significant higher expression of PDF 1.2 observed in the bacterized plants in response to subsequent pathogen challenge showed that FZB42 could enhance the lettuce defense response toward the fungal pathogen. To identify if surfactin or other nonribosomally synthesized secondary metabolites could elicit the observed enhanced defense gene expression, we examined two mutants of FZB42 deficient in production of surfactin and the lipopetides and polyketides, by expression analysis and pot experiments. In the absence of surfactin and other nonribosomally synthesized secondary metabolites, there was no enhanced PDF 1.2-mediated response to the pathogen challenge. Pot experiment results showed that the mutants failed to reduce disease incidence in lettuce as compared with the FZB42 wild type, indicating, that surfactin as well as other nonribosomally synthesized secondary metabolites play a role in the actual disease suppression and on lettuce health. In conclusion, our study showed that nonribosomally synthesized secondary metabolites of FZB42 are actually produced in the lettuce rhizosphere and contribute to the disease suppression by mediating plant defense gene expression toward the pathogen R. solani.

Postharvest application of a novel chitinase cloned from Metschnikowia fructicola and overexpressed in Pichia pastoris to control brown rot of peaches.

PubMed

Banani, Houda; Spadaro, Davide; Zhang, Dianpeng; Matic, Slavica; Garibaldi, Angelo; Gullino, Maria Lodovica

2015-04-16

Metschnikowia fructicola strain AP47 is a yeast antagonist against postharvest pathogens of fruits. The yeast was able to produce chitinase enzymes in the presence of pathogen cell wall. A novel chitinase gene MfChi (GenBank accession number HQ113461) was amplified from the genomic DNA of Metschnikowia fructicola AP47. Sequence analysis showed lack of introns, an open reading frame (ORF) of 1098 bp encoding a 365 amino acid protein with a calculated molecular weight of 40.9 kDa and a predicted pI of 5.27. MfChi was highly induced in Metschnikowia fructicola after interaction with Monilinia fructicola cell wall, suggesting a primary role of MfChi chitinase in the antagonistic activity of the yeast. The MfChi gene overexpressed in the heterologous expression system of Pichia pastoris KM71 and the recombinant chitinase showed high endochitinase activity towards 4-Nitrophenyl β-d-N,N',N″-triacetylchitotriose substrate. The antifungal activity of the recombinant chitinase was investigated against Monilinia fructicola and Monilinia laxa in vitro and on peaches. The chitinase significantly controlled the spore germination and the germ tube length of the tested pathogens in PDB medium and the mycelium diameter in PDA. The enzyme, when applied on peaches cv. Redhaven, successfully reduced brown rot severity. This work shows that the chitinase MfChi could be developed as a postharvest treatment with antimicrobial activity for fruit undergoing a short shelf life, and confirms that P. pastoris KM71 is a suitable microorganism for cost-effective large-scale production of recombinant chitinases. Copyright © 2015 Elsevier B.V. All rights reserved.

A novel, multiplexed, probe-based quantitative PCR assay for the soybean root- and stem-rot pathogen, Phytophthora sojae, utilizes its transposable element

PubMed Central

Haudenshield, James S.; Song, Jeong Y.; Hartman, Glen L.

2017-01-01

Phytophthora root rot of soybean [Glycine max (L.) Merr.] is caused by the oomycete Phytophthora sojae (Kaufm. & Gerd.). P. sojae has a narrow host range, consisting primarily of soybean, and it is a serious pathogen worldwide. It exists in root and stem tissues as mycelium, wherein it can form oospores which subsequently germinate to release motile, infectious zoospores. Molecular assays detecting DNA of P. sojae are useful in disease diagnostics, and for determining the presence of the organism in host tissues, soils, and runoff or ponded water from potentially infested fields. Such assays as published have utilized ITS sequences from the nuclear ribosomal RNA genes in conventional PCR or dye-binding quantitative PCR (Q-PCR) but are not amenable to multiplexing, and some of these assays did not utilize control strategies for type I or type II errors. In this study, we describe primers and a bifunctional probe with specificity to a gypsy-like retroelement in the P. sojae genome to create a fluorogenic 5’-exonuclease linear hydrolysis assay, with a multiplexed internal control reaction detecting an exogenous target to validate negative calls, and with uracil-deglycosylase-mediated protection against carryover contamination. The assay specifically detected 13 different P. sojae isolates, and excluded 17 other Phytophthora species along with 20 non-Phytophthora fungal and oomycete species pathogenic on soybean. A diagnostic limit of detection of 34 fg total P. sojae DNA was observed in serial dilutions, equivalent to 0.3 genome, and a practical detection sensitivity of four zoospores per sample was achieved, despite losses during DNA extraction. PMID:28441441

Stimulation by Erwinia carotovora of the synthesis of ethylene in cauliflower tissue

PubMed Central

Lund, Barbara M.; Mapson, L. W.

1970-01-01

The synthesis of ethylene by cauliflower floret tissue was increased when the tissue was inoculated with the soft-rot bacterium Erwinia carotovora. This effect was clearly associated with the production of pectic enzymes by the micro-organism. These enzymes, acting together with the plant enzymes, stimulated the production of ethylene from methionine. The increased synthetic activity was due to the release and increased activity of a glucose oxidase enzyme apparently attached to plant cell-wall material and liberated by the action of pectic enzymes of the bacterium. ImagesPLATE 1 PMID:5488914

Fumonisin B(1)-nonproducing strains of Fusarium verticillioides cause maize (Zea mays) ear infection and ear rot.

PubMed

Desjardins, A E; Plattner, R D

2000-11-01

Fumonisins are polyketide mycotoxins produced by Fusarium verticillioides (synonym F. moniliforme), a major pathogen of maize (Zea mays) worldwide. Most field strains produce high levels of fumonisin B(1) (FB(1)) and low levels of the less-oxygenated homologues FB(2) and FB(3), but fumonisin B(1)-nonproducing field strains have been obtained by natural variation. To test the role of various fumonisins in pathogenesis on maize under field conditions, one strain producing FB(1), FB(2), and FB(3), one strain producing only FB(2), one strain producing only FB(3), and one fumonisin-nonproducing strain were applied to ears via the silk channel and on seeds at planting. Disease severity on the harvested ears was evaluated by visible symptoms and by weight percent symptomatic kernels. Fumonisin levels in kernels were determined by high-performance liquid chromatography. The presence of the applied FB(1)-nonproducing strains in kernels was determined by analysis of recovered strains for fumonisin production and other traits. All three FB(1)-nonproducing strains were able to infect ears following either silk-channel application or seed application at planting and were as effective as the FB(1)-producing strain in causing ear rot following silk-channel application. These results indicate that production of FB(1), FB(2), or FB(3) is not required for F. verticillioides to cause maize ear infection and ear rot.

Diversity and activity of biosurfactant-producing Pseudomonas in the rhizosphere of black pepper in Vietnam.

PubMed

Tran, H; Kruijt, M; Raaijmakers, J M

2008-03-01

Phytophthora capsici is a major pathogen of black pepper and zoospores play an important role in the infection process. Fluorescent pseudomonads that produce biosurfactants with zoosporicidal activities were isolated from the black pepper rhizosphere in Vietnam, and their genotypic diversity and potential to control Phy. capsici root rot was determined. Biosurfactant-producing pseudomonads were genotypically and biochemically characterized by BOX-polymerase chain reaction (PCR), 16S-rDNA sequencing, reverse-phase-high-performance liquid chromatography and liquid chromatography-mass spectrometry analyses. Biosurfactant-producing fluorescent pseudomonads make up c. 1.3% of the culturable Pseudomonas population in the rhizosphere of black pepper. Although BOX-PCR revealed substantial genotypic diversity, the isolates were shown to produce the same biosurfactants and were all identified as Pseudomonas putida. When applied to black pepper stem cuttings, several of the biosurfactant-producing strains provided significant disease control. In absence of the disease, several of the bacterial strains promoted shoot and root growth of black pepper stem cuttings. Biosurfactant-producing pseudomonads indigenous to the rhizosphere of black pepper plants are genotypically diverse and provide a novel resource for the control of Phy. capsici root rot and growth promotion of black pepper stem cuttings. The results of this study provide a strong basis for further development of supplementary strategies with antagonistic bacteria to control foot and root rot of black pepper and to promote plant growth.

Interactions Between Frankliniella fusca and Pantoea ananatis in the Center Rot Epidemic of Onion (Allium cepa).

PubMed

Dutta, Bhabesh; Gitaitis, Ronald; Barman, Apurba; Avci, Utku; Marasigan, Kathleen; Srinivasan, Rajagopalbabu

2016-09-01

An Enterobacteriaceae bacterium, Pantoea ananatis (Serrano) Mergaert, is the causal agent of an economically important disease of onion, center rot. P. ananatis is transmitted by an onion-infesting thrips, Frankliniella fusca (Hinds). However, interactions between F. fusca and P. ananatis as well as transmission mechanisms largely remain uncharacterized. This study investigated P. ananatis acquisition by thrips and transstadial persistence. Furthermore, the effects of bacterial acquisition on thrips fitness were also evaluated. When thrips larvae and adults were provided with acquisition access periods (AAP) on peanut leaflets contaminated with the bacterium, an exponentially positive relationship was observed between AAP and P. ananatis acquisition (R(2) ≥ 0.77, P = 0.01). P. ananatis persisted in thrips through several life stages (larvae, pupae, and adult). Despite the bacterial persistence, no significant effects on thrips fitness parameters such as fecundity and development were observed. Immunofluorescence microscopy of adult thrips with P. ananatis-specific antibody after 48 h AAP on contaminated food revealed that the bacterium was localized only in the gut. These results suggested that the pathogen is not circulative and could be transmitted through feces. Mechanical inoculation of onion seedlings with fecal rinsates produced center rot symptoms, whereas inoculation with rinsates potentially containing salivary secretions did not. These results provide evidence for stercorarian transmission (transmission through feces) of P. ananatis by F. fusca.

Microbial antagonism as a potential solution for controlling selected root pathogens of crops

NASA Astrophysics Data System (ADS)

Cooper, Sarah; Agnew, Linda; Pereg, Lily

2016-04-01

Root pathogens of crops can cause large reduction in yield, however, there is a limited range of effective methods to control such pathogens. Soilborne pathogens that infect roots often need to survive in the rhizosphere, where there is high competition from other organisms. In such hot spots of microbial activity and growth, supported by root exudates, microbes have evolved antagonistic mechanisms that give them competitive advantages in winning the limited resources. Among these mechanisms is antibiosis, with production of some significant antifungal compounds including, antibiotics, volatile organic compounds, hydrogen cyanide and lytic enzymes. Some of these mechanisms may suppress disease through controlling the growth of root pathogens. In this project we isolated various fungi and bacteria that suppress the growth of cotton pathogens in vitro. The pathogen-suppressive microbes were isolated from cotton production soils that are under different management strategies, with and without the use of organic amendments. The potential of pathogen-suppressing microbes for controlling the black root rot disease, caused by the soilborne pathogen Thielaviopsis basicola, was confirmed using soil assays. We identified isolates with potential use as inoculant for cotton production in Australia. Having isolated a diverse group of antagonistic microbes enhances the probability that some would survive well in the soil and provide an alternative approach to address the problem of root disease affecting agricultural crops.

Seed treatments to control seedborne fungal pathogens of vegetable crops.

PubMed

Mancini, Valeria; Romanazzi, Gianfranco

2014-06-01

Vegetable crops are frequently infected by fungal pathogens, which can include seedborne fungi. In such cases, the pathogen is already present within or on the seed surface, and can thus cause seed rot and seedling damping-off. Treatment of vegetable seeds has been shown to prevent plant disease epidemics caused by seedborne fungal pathogens. Furthermore, seed treatments can be useful in reducing the amounts of pesticides required to manage a disease, because effective seed treatments can eliminate the need for foliar application of fungicides later in the season. Although the application of fungicides is almost always effective, their non-target environmental impact and the development of pathogen resistance have led to the search for alternative methods, especially in the past few years. Physical treatments that have already been used in the past and treatments with biopesticides, such as plant extracts, natural compounds and biocontrol agents, have proved to be effective in controlling seedborne pathogens. These have been applied alone or in combination, and they are widely used owing to their broad spectrum in terms of disease control and production yield. In this review, the effectiveness of different seed treatments against the main seedborne pathogens of some important vegetable crops is critically discussed. © 2013 Society of Chemical Industry.

Morphological and molecular characterization of Fusarium spp pathogenic to pecan tree in Brazil.

PubMed

Lazarotto, M; Milanesi, P M; Muniz, M F B; Reiniger, L R S; Beltrame, R; Harakava, R; Blume, E

2014-11-11

The occurrence of Fusarium spp associated with pecan tree (Carya illinoinensis) diseases in Brazil has been observed in recent laboratory analyses in Rio Grande do Sul State. Thus, in this study, we i) obtained Fusarium isolates from plants with disease symptoms; ii) tested the pathogenicity of these Fusarium isolates to pecan; iii) characterized and grouped Fusarium isolates that were pathogenic to the pecan tree based on morphological characteristics; iv) identified Fusarium spp to the species complex level through TEF-1α sequencing; and v) compared the identification methods used in the study. Fifteen isolates collected from the inflorescences, roots, and seeds of symptomatic plants (leaf necrosis or root rot) were used for pathogenicity tests. Morphological characterization was conducted using only pathogenic isolates, for a total of 11 isolates, based on the mycelial growth rate, sporulation, colony pigmentation, and conidial length and width variables. Pathogenic isolates were grouped based on morphological characteristics, and molecular characterization was performed by sequencing TEF-1α genes. Pathogenic isolates belonging to the Fusarium chlamydosporum species complex, Fusarium graminearum species complex, Fusarium proliferatum, and Fusarium oxysporum were identified based on the TEF-1α region. Morphological characteristics were used to effectively differentiate isolates and group the isolates according to genetic similarity, particularly conidial width, which emerged as a key morphological descriptor in this study.

Combination of antagonistic yeasts with two food additives for control of brown rot caused by Monilinia fructicola on sweet cherry fruit.

PubMed

Qin, G Z; Tian, S P; Xu, Y; Chan, Z L; Li, B Q

2006-03-01

To evaluate beneficial effect of two food additives, ammonium molybdate (NH4-Mo) and sodium bicarbonate (NaBi), on antagonistic yeasts for control of brown rot caused by Monilinia fructicola in sweet cherry fruit under various storage conditions. The mechanisms of action by which food additives enhance the efficacy of antagonistic yeasts were also evaluated. Biocontrol activity of Pichia membranefaciens and Cryptococcus laurentii against brown rot in sweet cherry fruit was improved by addition of 5 mmol l(-1) NH4-Mo or 2% NaBi when stored in air at 20 and 0 degrees C, and in controlled atmosphere (CA) storage with 10% O2 + 10% CO2 at 0 degrees C. Population dynamics of P. membranefaciens in the wounds of fruit were inhibited by NH4-Mo at 20 degrees C after 1 day of incubation and growth of C. laurentii was inhibited by NH4-Mo at 0 degrees C in CA storage after 60 days. In contrast, NaBi did not significantly influence growth of the two yeasts in fruit wounds under various storage conditions except that the growth of P. membranefaciens was stimulated after storage for 45 days at 0 degrees C in CA storage. When used alone, the two additives showed effective control of brown rot in sweet cherry fruit and the efficacy was closely correlated with the concentrations used. The result of in vitro indicated that growth of M. fructicola was significantly inhibited by NH4-Mo and NaBi. Application of additives improved biocontrol of brown rot on sweet cherry fruit under various storage conditions. It is postulated that the enhancement of disease control is directly because of the inhibitory effects of additives on pathogen growth, and indirectly because of the relatively little influence of additives on the growth of antagonistic yeasts. The results obtained in this study suggest that an integration of NH4-Mo or NaBi with biocontrol agents has great potential in commercial management of postharvest diseases of fruit.

Transcriptome profiling of soybean (Glycine max) roots challenged with pathogenic and non-pathogenic isolates of Fusarium oxysporum.

PubMed

Lanubile, Alessandra; Muppirala, Usha K; Severin, Andrew J; Marocco, Adriano; Munkvold, Gary P

2015-12-21

Fusarium oxysporum is one of the most common fungal pathogens causing soybean root rot and seedling blight in U.S.A. In a recent study, significant variation in aggressiveness was observed among isolates of F. oxysporum collected from roots in Iowa, ranging from highly pathogenic to weakly or non-pathogenic isolates. We used RNA-seq analysis to investigate the molecular aspects of the interactions of a partially resistant soybean genotype with non-pathogenic/pathogenic isolates of F. oxysporum at 72 and 96 h post inoculation (hpi). Markedly different gene expression profiles were observed in response to the two isolates. A peak of highly differentially expressed genes (HDEGs) was triggered at 72 hpi in soybean roots and the number of HDEGs was about eight times higher in response to the pathogenic isolate compared to the non-pathogenic one (1,659 vs. 203 HDEGs, respectively). Furthermore, the magnitude of induction was much greater in response to the pathogenic isolate. This response included a stronger activation of defense-related genes, transcription factors, and genes involved in ethylene biosynthesis, secondary and sugar metabolism. The obtained data provide an important insight into the transcriptional responses of soybean-F. oxysporum interactions and illustrate the more drastic changes in the host transcriptome in response to the pathogenic isolate. These results may be useful in the developing new methods of broadening resistance of soybean to F. oxysporum, including the over-expression of key soybean genes.

Highly uniform residual layers for arrays of 3D nanoimprinted cavities in Fabry-Pérot-filter-array-based nanospectrometers

NASA Astrophysics Data System (ADS)

Memon, Imran; Shen, Yannan; Khan, Abdullah; Woidt, Carsten; Hillmer, Hartmut

2016-04-01

Miniaturized optical spectrometers can be implemented by an array of Fabry-Pérot (FP) filters. FP filters are composed of two highly reflecting parallel mirrors and a resonance cavity. Each filter transmits a small spectral band (filter line) depending on its individual cavity height. The optical nanospectrometer, a miniaturized FP-based spectrometer, implements 3D NanoImprint technology for the fabrication of multiple FP filter cavities in a single process step. However, it is challenging to avoid the dependency of residual layer (RL) thickness on the shape of the printed patterns in NanoImprint. Since in a nanospectrometer the filter cavities vary in height between neighboring FP filters and, thus, the volume of each cavity varies causing that the RL varies slightly or noticeably between different filters. This is one of the few disadvantages of NanoImprint using soft templates such as substrate conformal imprint lithography which is used in this paper. The advantages of large area soft templates can be revealed substantially if the problem of laterally inhomogeneous RLs can be avoided or reduced considerably. In the case of the nanospectrometer, non-uniform RLs lead to random variations in the designed cavity heights resulting in the shift of desired filter lines. To achieve highly uniform RLs, we report a volume-equalized template design with the lateral distribution of 64 different cavity heights into several units with each unit comprising four cavity heights. The average volume of each unit is kept constant to obtain uniform filling of imprint material per unit area. The imprint results, based on the volume-equalized template, demonstrate highly uniform RLs of 110 nm thickness.

Expression Profiling of Castanea Genes during Resistant and Susceptible Interactions with the Oomycete Pathogen Phytophthora cinnamomi Reveal Possible Mechanisms of Immunity

PubMed Central

Santos, Carmen; Duarte, Sofia; Tedesco, Sara; Fevereiro, Pedro; Costa, Rita L.

2017-01-01

The most dangerous pathogen affecting the production of chestnuts is Phytophthora cinnamomi a hemibiotrophic that causes root rot, also known as ink disease. Little information has been acquired in chestnut on the molecular defense strategies against this pathogen. The expression of eight candidate genes potentially involved in the defense to P. cinnamomi was quantified by digital PCR in Castanea genotypes showing different susceptibility to the pathogen. Seven of the eight candidate genes displayed differentially expressed levels depending on genotype and time-point after inoculation. Cast_Gnk2-like revealed to be the most expressed gene across all experiments and the one that best discriminates between susceptible and resistant genotypes. Our data suggest that the pre-formed defenses are crucial for the resistance of C. crenata to P. cinnamomi. A lower and delayed expression of the eight studied genes was found in the susceptible Castanea sativa, which may be related with the establishment and spread of the disease in this species. A working model integrating the obtained results is presented. PMID:28443110

Potential of a new strain of Bacillus amyloliquefaciens BUZ-14 as a biocontrol agent of postharvest fruit diseases.

PubMed

Calvo, H; Marco, P; Blanco, D; Oria, R; Venturini, M E

2017-05-01

The biocontrol potential of the Bacillus amyloliquefaciens strain BUZ-14 was tested against the main postharvest diseases of orange, apple, grape and stone fruit. After characterizing the temperature and pH growth curves of strain BUZ-14, its in vitro antifungal activity was determined against Botrytis cinerea, Monilinia fructicola, M. laxa, Penicillium digitatum, P. expansum and P. italicum. Subsequently, in vivo activity was tested against these pathogens by treating fruit with cells, endospores and cell-free supernatants. The in vitro results showed that BUZ-14 inhibited the growth of all the pathogens tested corresponding to the least susceptible species, P. italicum, and the most susceptible, M. laxa. In vivo tests corroborated these results as most of the treatments decreased the incidence of brown rot in stone fruit from 100% to 0%, establishing 10 7  CFU mL -1 as the minimum inhibitory concentration. For the Penicillium species a preventive treatment inhibited P. digitatum and P. italicum growth in oranges and reduced P. expansum incidence in apples from 100% to 20%. Finally, it has been demonstrated that BUZ-14 was able to survive and to control brown rot in peaches stored at cool temperatures, making it a very suitable biocontrol agent for application during the post-harvest storage and marketing of horticultural products. Copyright © 2016 Elsevier Ltd. All rights reserved.

Agro-ecological variations of sheath rot disease of rice caused by Sarocladium oryzae and DNA fingerprinting of the pathogen's population structure.

PubMed

Tajul Islam Chowdhury, M; Salim Mian, M; Taher Mia, M A; Rafii, M Y; Latif, M A

2015-12-28

To examine the impact of regional and seasonal variations on the incidence and severity of sheath rot, a major seed-borne disease of rice caused by Sarocladium oryzae, data on incidence and severity were collected from 27 selected fields in the Gazipur, Rangpur, Bogra, Chittagong, Comilla, Gopalgonj, Jessore, Manikgonj, and Bhola districts of Bangladesh in rain-fed and irrigated conditions. Cultural variability of 29 pathogen isolates obtained from 8 different locations was studied on potato dextrose agar (PDA) and genetic variability was determined by DNA fingerprinting using variable number tandem repeat-polymerase chain reaction markers. Overall, disease incidence and severity were higher in irrigated rice. Disease incidence and severity were highest in the Bhola district in rain-fed rice and lowest in irrigated rice. Mycelial growth of 29 representative isolates was found to vary on PDA and the isolates were divided into 6 groups. The range of the overall size of conidia of the selected isolates was 2.40-7.20 x 1.20-2.40 μm. Analysis of the DNA fingerprint types of the 29 isolates of S. oryzae, obtained from the amplification reactions, revealed 10 fingerprinting types (FPTs) that were 80% similar. FPT-1 was the largest group and included 13 isolates (44.8%), while FPT-2 was the third largest group and included 3 isolates. Each of FPT-3, 4, 5, and 6 included only 1 isolate. We observed no relationship between cultural and genetic groupings.

Evidence that the Ceratobasidium-like white-thread blight and black rot fungal pathogens from persimmon and tea crops in the Brazilian Atlantic Forest agroecosystem are two distinct phylospecies

PubMed Central

Ceresini, Paulo C.; Costa-Souza, Elaine; Zala, Marcello; Furtado, Edson L.; Souza, Nilton L.

2012-01-01

The white-thread blight and black rot (WTBR) caused by basidiomycetous fungi of the genus Ceratobasidium is emerging as an important plant disease in Brazil, particularly for crop species in the Ericales such as persimmon (Diospyros kaki) and tea (Camellia sinensis). However, the species identity of the fungal pathogen associated with either of these hosts is still unclear. In this work, we used sequence variation in the internal transcribed spacer regions, including the 5.8S coding region of rDNA (ITS-5.8S rDNA), to determine the phylogenetic placement of the local white-thread-blight-associated populations of Ceratobasidium sp. from persimmon and tea, in relation to Ceratobasidium species already described world-wide. The two sister populations of Ceratobasidium sp. from persimmon and tea in the Brazilian Atlantic Forest agroecosystem most likely represent distinct species within Ceratobasidium and are also distinct from C. noxium, the etiological agent of the first description of white-thread blight disease that was reported on coffee in India. The intraspecific variation for the two Ceratobasidium sp. populations was also analyzed using three mitochondrial genes (ATP6, nad1 and nad2). As reported for other fungi, variation in nuclear and mitochondrial DNA was incongruent. Despite distinct variability in the ITS-rDNA region these two populations shared similar mitochondrial DNA haplotypes. PMID:22888299

Natural variation of potato allene oxide synthase 2 causes differential levels of jasmonates and pathogen resistance in Arabidopsis

PubMed Central

Pajerowska-Mukhtar, Karolina M.; Mukhtar, M. Shahid; Guex, Nicolas; Halim, Vincentius A.; Rosahl, Sabine; Somssich, Imre E.

2008-01-01

Natural variation of plant pathogen resistance is often quantitative. This type of resistance can be genetically dissected in quantitative resistance loci (QRL). To unravel the molecular basis of QRL in potato (Solanum tuberosum), we employed the model plant Arabidopsis thaliana for functional analysis of natural variants of potato allene oxide synthase 2 (StAOS2). StAOS2 is a candidate gene for QRL on potato chromosome XI against the oömycete Phytophthora infestans causing late blight, and the bacterium Erwinia carotovora ssp. atroseptica causing stem black leg and tuber soft rot, both devastating diseases in potato cultivation. StAOS2 encodes a cytochrome P450 enzyme that is essential for biosynthesis of the defense signaling molecule jasmonic acid. Allele non-specific dsRNAi-mediated silencing of StAOS2 in potato drastically reduced jasmonic acid production and compromised quantitative late blight resistance. Five natural StAOS2 alleles were expressed in the null Arabidopsis aos mutant under control of the Arabidopsis AOS promoter and tested for differential complementation phenotypes. The aos mutant phenotypes evaluated were lack of jasmonates, male sterility and susceptibility to Erwinia carotovora ssp. carotovora. StAOS2 alleles that were associated with increased disease resistance in potato complemented all aos mutant phenotypes better than StAOS2 alleles associated with increased susceptibility. First structure models of ‘quantitative resistant’ versus ‘quantitative susceptible’ StAOS2 alleles suggested potential mechanisms for their differential activity. Our results demonstrate how a candidate gene approach in combination with using the homologous Arabidopsis mutant as functional reporter can help to dissect the molecular basis of complex traits in non model crop plants. Electronic supplementary material The online version of this article (doi:10.1007/s00425-008-0737-x) contains supplementary material, which is available to authorized users. PMID:18431595

[Induction of polygalacturonases important in pathogenicity of Pseudomonas solanacearum

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

Not Available

1992-01-01

Recent studies on the importance of hydroxyproline-rich glycoproteins (HPRG's) in the nature and function of plant cell walls have led to the question as to whether proteolytic enzymes are also involved in tissue maceration and act in concert with other cell wall degrading enzymes in the process. The primary objective of this research was to determine whether proteolytic enzymes, in combination with other enzymes, are involved in the degradation of plant cell walls and thus may be essential for pathogenesis by certain soft rot bacteria. The proteolytic enzymes of Erwinia carotovora subsp.carotovora (Ecc) grown on various media were examined bymore » isoelectrofocusing in polyacrylamide gels over a pH range of 3-10. In addition to the main protease present in culture filtrates, low concentrations of several other proteases were present in extracts from potato tubers infected by Ecc. These enzymes degraded gelatin, soluble collagen, and Hide Powder Azure, and showed weak activity on casein, but did not degrade insoluble collagen or elastin. Ecc proteases appear capable of degrading at least one type of cell wall protein in vitro, but we were unable to obtain evidence that these proteases can attack cell wall proteins in muro. The results indicate that some glycosidic alkali- labile bonds have to be broken befor Ecc proteases can degrade cell wall proteins. Thus, these proteases may play a role in cell wall degradation only when acting in concert with other enzymes that split glycosidic bonds.« less

[Induction of polygalacturonases important in pathogenicity of Pseudomonas solanacearum

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

Not Available

1992-12-31

Recent studies on the importance of hydroxyproline-rich glycoproteins (HPRG`s) in the nature and function of plant cell walls have led to the question as to whether proteolytic enzymes are also involved in tissue maceration and act in concert with other cell wall degrading enzymes in the process. The primary objective of this research was to determine whether proteolytic enzymes, in combination with other enzymes, are involved in the degradation of plant cell walls and thus may be essential for pathogenesis by certain soft rot bacteria. The proteolytic enzymes of Erwinia carotovora subsp.carotovora (Ecc) grown on various media were examined bymore » isoelectrofocusing in polyacrylamide gels over a pH range of 3-10. In addition to the main protease present in culture filtrates, low concentrations of several other proteases were present in extracts from potato tubers infected by Ecc. These enzymes degraded gelatin, soluble collagen, and Hide Powder Azure, and showed weak activity on casein, but did not degrade insoluble collagen or elastin. Ecc proteases appear capable of degrading at least one type of cell wall protein in vitro, but we were unable to obtain evidence that these proteases can attack cell wall proteins in muro. The results indicate that some glycosidic alkali- labile bonds have to be broken befor Ecc proteases can degrade cell wall proteins. Thus, these proteases may play a role in cell wall degradation only when acting in concert with other enzymes that split glycosidic bonds.« less

The crystal structure of pectate lyase peli from soft rot pathogen Erwinia chrysanthemi in complex with its substrate.

PubMed

Creze, Christophe; Castang, Sandra; Derivery, Emmanuel; Haser, Richard; Hugouvieux-Cotte-Pattat, Nicole; Shevchik, Vladimir E; Gouet, Patrice

2008-06-27

The crystallographic structure of the family 3 polysaccharide lyase (PL-3) PelI from Erwinia chrysanthemi has been solved to 1.45 A resolution. It consists of an N-terminal domain harboring a fibronectin type III fold linked to a catalytic domain displaying a parallel beta-helix topology. The N-terminal domain is located away from the active site and is not involved in the catalytic process. After secretion in planta, the two domains are separated by E. chrysanthemi proteases. This event turns on the hypersensitive response of the host. The structure of the single catalytic domain determined to 2.1 A resolution shows that the domain separation unveils a "Velcro"-like motif of asparagines, which might be recognized by a plant receptor. The structure of PelI in complex with its substrate, a tetragalacturonate, has been solved to 2.3 A resolution. The sugar binds from subsites -2 to +2 in one monomer of the asymmetric unit, although it lies on subsites -1 to +3 in the other. These two "Michaelis complexes" have never been observed simultaneously before and are consistent with the dual mode of bond cleavage in this substrate. The bound sugar adopts a mixed 2(1) and 3(1) helical conformation similar to that reported in inactive mutants from families PL-1 and PL-10. However, our study suggests that the catalytic base in PelI is not a conventional arginine but a lysine as proposed in family PL-9.

INCIDENCE AND SEVERITY OF LEAF AND FRUIT DISEASES OF PLUMS IN LATVIA.

PubMed

Grantina-Ievina, L; Stanke, L

2015-01-01

In the present study six plum orchards in Latvia were examined during 2014. One orchard was commercial with integrated pest management (IPM) practices, one was with organic management, two orchards were scientific collections and in two orchards plums were grown as a minor crop, using IPM practices. The shot-hole disease (Wilsonomyces carpophilus) and fruit rot were monitored in the field. Samples of twigs and leaves were taken for further examination if some other disease symptoms were observed. In total, 50 European plum (Prunus domestica) and six diploid plum cultivars were inspected. The fruit rot was assessed also in the laboratory to determine the latent infection with Monilinia spp. on immature fruits. Monilinia spp. isolates from all orchards were subjected to fungicide sensitivity tests. Incidence and severity of shot-hole disease was significantly different among various orchards when the same cultivar was compared, as well as between diploid and European plum cultivars. The average incidence of shot-hole disease was 41% in diploid plums and 80% in European plums, while the average severity was 9 and 15%, respectively. In the field, fruit rot caused only by Monilinia spp. was detected. The average incidence of brown rot on diploid plums was less than 1%, but on European plums it was 3.6%. The latent infection tests showed that plum fruits had higher incidence of brown rot than was observed in the field, up to 44% on particular cultivars. Additionally, from the fruits subjected to these tests, Botrytis cinerea, Diaporthe eres and Colletotrichum spp. were isolated. This means that in specific weather and management conditions the fruit rot incidence in the field could be several times higher. Examination of samples of twigs, leaves and fruits in the laboratory showed the presence of D. eres in samples from all orchards. In one of the scientific collections D. eres was isolated from twigs, leaves and fruits, and was more often found on the individuals located in the part of the orchard close to hedge. In other orchards this fungus was isolated only from fruits, and mainly from the latent infection tests. Monilinia spp. isolates showed high sensitivity to dithianon, penconazole, mancozeb and boscalid with pyraclostrobin, but lower sensitivity to cyprodinil. Several fungi that are known to be antagonistic to pathogenic fungi were isolated from all orchards: Epicoccum nigrum, Clonostachys rosea and Aureobasidium pullulans, mainly from the fruits of latency tests and leaves with disease symptoms.

Fusarium diseases of maize associated with mycotoxin contamination of agricultural products intended to be used for food and feed.

PubMed

Oldenburg, Elisabeth; Höppner, Frank; Ellner, Frank; Weinert, Joachim

2017-08-01

Infections of maize with phytopathogenic and toxinogenic Fusarium spp. may occur throughout the cultivation period. This can cause different types of diseases in vegetative and generative organs of the plant. Along with these infections, mycotoxins are often produced and accumulated in affected tissues, which could pose a significant risk on human and animal health when entering the food and feed chain. Most important fungal species infecting European maize belong to the Fusarium sections Discolour and Liseola, the first being more prevalent in cooler and humid climate regions than the second predominating in warmer and dryer areas. Coexistence of several Fusarium spp. pathogens in growing maize under field conditions is the usual case and may lead to multi-contamination with mycotoxins like trichothecenes, zearalenone and fumonisins. The pathways how the fungi gain access to the target organs of the plant are extensively described in relation to specific symptoms of typical rot diseases regarding ears, kernels, rudimentary ears, roots, stem, leaves, seed and seedlings. Both Gibberella and Fusarium ear rots are of major importance in affecting the toxinogenic quality of grain or ear-based products as well as forage maize used for human or animal nutrition. Although rudimentary ears may contain high amounts of Fusarium toxins, the contribution to the contamination of forage maize is minor due to their small proportion on the whole plant dry matter yield. The impact of foliar diseases on forage maize contamination is regarded to be low, as Fusarium infections are restricted to some parts on the leaf sheaths and husks. Mycotoxins produced in rotted basal part of the stem may contribute to forage maize contamination, but usually remain in the stubbles after harvest. As the probability of a more severe disease progression is increasing with a prolonged cultivation period, maize should be harvested at the appropriate maturity stage to keep Fusarium toxin contamination as low as possible. Ongoing surveillance and research is needed to recognise changes in the spectrum of dominating Fusarium pathogens involved in mycotoxin contamination of maize to ensure safety in the food and feed chain.

Characterization and Pathogenicity of New Record of Anthracnose on Various Chili Varieties Caused by Colletotrichum scovillei in Korea.

PubMed

Oo, May Moe; Lim, GiTaek; Jang, Hyun A; Oh, Sang-Keun

2017-09-01

The anthracnose disease caused by Colletotrichum species is well-known as a major plant pathogen that primarily causes fruit rot in pepper and reduces its marketability. Thirty-five isolates representing species of Colletotrichum were obtained from chili fruits showing anthracnose disease symptoms in Chungcheongnam-do and Chungcheongbuk-do, South Korea. These 35 isolates were characterized according to morphological characteristics and nucleotide sequence data of internal transcribed spacer, glyceraldehyde-3-phosphate-dehydrogenase, and β-tubulin. The combined dataset shows that all of these 35 isolates were identified as C. scovillei and morphological characteristics were directly correlated with the nucleotide sequence data. Notably, these isolates were recorded for the first time as the causes of anthracnose caused by C. scovillei on pepper in Korea. Forty cultivars were used to investigate the pathogenicity and to identify the possible source of resistance. The result reveals that all of chili cultivars used in this study are susceptible to C. scovillei .

Characterization and Pathogenicity of New Record of Anthracnose on Various Chili Varieties Caused by Colletotrichum scovillei in Korea

PubMed Central

Oo, May Moe; Lim, GiTaek; Jang, Hyun A

2017-01-01

The anthracnose disease caused by Colletotrichum species is well-known as a major plant pathogen that primarily causes fruit rot in pepper and reduces its marketability. Thirty-five isolates representing species of Colletotrichum were obtained from chili fruits showing anthracnose disease symptoms in Chungcheongnam-do and Chungcheongbuk-do, South Korea. These 35 isolates were characterized according to morphological characteristics and nucleotide sequence data of internal transcribed spacer, glyceraldehyde-3-phosphate-dehydrogenase, and β-tubulin. The combined dataset shows that all of these 35 isolates were identified as C. scovillei and morphological characteristics were directly correlated with the nucleotide sequence data. Notably, these isolates were recorded for the first time as the causes of anthracnose caused by C. scovillei on pepper in Korea. Forty cultivars were used to investigate the pathogenicity and to identify the possible source of resistance. The result reveals that all of chili cultivars used in this study are susceptible to C. scovillei. PMID:29138623

Growth in microgravity increases susceptibility of soybean to a fungal pathogen

NASA Technical Reports Server (NTRS)

Ryba-White, M.; Nedukha, O.; Hilaire, E.; Guikema, J. A.; Kordyum, E.; Leach, J. E.; Spooner, B. S. (Principal Investigator)

2001-01-01

The influence of microgravity on the susceptibility of soybean roots to Phytophthora sojae was studied during the Space Shuttle Mission STS-87. Seedlings of soybean cultivar Williams 82 grown in spaceflight or at unit gravity were untreated or inoculated with the soybean root rot pathogen P. sojae. At 3, 6 and 7 d after launch while still in microgravity, seedlings were photographed and then fixed for subsequent microscopic analysis. Post-landing analysis of the seedlings revealed that at harvest day 7 the length of untreated roots did not differ between flight and ground samples. However, the flight-grown roots infected with P. sojae showed more disease symptoms (percentage of brown and macerated areas) and the root tissues were more extensively colonized relative to the ground controls exposed to the fungus. Ethylene levels were higher in spaceflight when compared to ground samples. These data suggest that soybean seedlings grown in microgravity are more susceptible to colonization by a fungal pathogen relative to ground controls.

Candida sake CPA-1 and other biologically based products as potential control strategies to reduce sour rot of grapes.

PubMed

Calvo-Garrido, C; Viñas, I; Elmer, P; Usall, J; Teixidó, N

2013-10-01

Sour rot of grapes is becoming increasingly important disease in many wine-growing regions, while consistent chemical or biological control has not been reported. Authors evaluated relative incidence and severity of sour rot in untreated grapevines and the effect of different biologically based treatments on sour rot at harvest. Applications of Candida sake CPA-1 plus Fungicover® , Ulocladium oudemansii and chitosan were carried out in an organic vineyard in Lleida area, Spain, during the 2009 and 2010 growing seasons. At harvest, incidence and severity of sour rot were assessed. Significantly higher incidence and severity of sour rot were observed in untreated plots in 2009, when meteorological conditions after veraison were warmer. All treatments including C. sake CPA-1 significantly reduced (P < 0·05) severity of sour rot in both seasons, ranging from 40 to 67% compared with the untreated control. Incidence of sour rot was not significantly reduced by any treatment. This study helps to characterize development of sour rot in the dry Mediterranean climate conditions of the experiment, whereas also represents the first report of biological control of sour rot. Treatments with the tested biologically based products are a promising strategy to control sour rot. Studies on sour rot of grapes are scarce in literature, and this is the first work specifically evaluating sour rot in Spanish vineyards. Sour rot control in field conditions through applications of antagonistic micro-organisms is reported for first time in this study, showing elevated severity reductions (40-67% compared with control). As there are no options available for sour rot control in vineyards, results point Candida sake CPA-1 as an interesting control strategy against grape bunch rots. © 2013 The Society for Applied Microbiology.

De novo genome assembly of the soil-borne fungus and tomato pathogen Pyrenochaeta lycopersici

PubMed Central

2014-01-01

Background Pyrenochaeta lycopersici is a soil-dwelling ascomycete pathogen that causes corky root rot disease in tomato (Solanum lycopersicum) and other Solanaceous crops, reducing fruit yields by up to 75%. Fungal pathogens that infect roots receive less attention than those infecting the aerial parts of crops despite their significant impact on plant growth and fruit production. Results We assembled a 54.9Mb P. lycopersici draft genome sequence based on Illumina short reads, and annotated approximately 17,000 genes. The P. lycopersici genome is closely related to hemibiotrophs and necrotrophs, in agreement with the phenotypic characteristics of the fungus and its lifestyle. Several gene families related to host–pathogen interactions are strongly represented, including those responsible for nutrient absorption, the detoxification of fungicides and plant cell wall degradation, the latter confirming that much of the genome is devoted to the pathogenic activity of the fungus. We did not find a MAT gene, which is consistent with the classification of P. lycopersici as an imperfect fungus, but we observed a significant expansion of the gene families associated with heterokaryon incompatibility (HI). Conclusions The P. lycopersici draft genome sequence provided insight into the molecular and genetic basis of the fungal lifestyle, characterizing previously unknown pathogenic behaviors and defining strategies that allow this asexual fungus to increase genetic diversity and to acquire new pathogenic traits. PMID:24767544

Conjunctively screening of biocontrol agents (BCAs) against fusarium root rot and fusarium head blight caused by Fusarium graminearum.

PubMed

Wang, Lu-Yao; Xie, Yue-Shen; Cui, Yuan-Yu; Xu, Jianjun; He, Wei; Chen, Huai-Gu; Guo, Jian-Hua

2015-08-01

Fusarium root-rot and fusarium head blight are plant diseases caused by Fusarium sp. in different growth periods of wheat, bring heavy losses to crop production in China. This research is aiming to screen biocontrol agents conjunctively for controlling these two diseases at the same time, as well as evaluate our previous BCAs (Biological Control Agents) screening strategies in more complex situation, considering biocontrol is well concerned as an environmental-friendly plant disease controlling method. Totally 966 bacterial isolates were screened from different parts of wheat tissues, of which potential biocontrol values were detected according to their abilities in antagonism inhibition and secreting extracellular hydrolytic enzyme. Biocontrol tests against fusarium root rot and fusarium head blight were carried out on 37 bacterial isolates with potential biocontrol capacity after pre-selection through ARDRA- and BOX-PCR analysis on strains with high assessment points. We acquired 10 BCAs with obvious biocontrol efficacy (more than 40%) in greenhouse and field tests. Pseudomonas fluorescens LY1-8 performed well in both two tests (biocontrol efficacy: 44.62% and 58.31%), respectively. Overall, correlation coefficient is 0.720 between assessment values of 37 tested BCA strains and their biocontrol efficacy in trails against fusarium root rot; correlation coefficient is 0.806 between their assessment values and biocontrol efficacy in trails against fusarium head blight. We acquired 10 well-performed potential BCAs, especially P. fluorescens LY1-8 displayed good biocontrol capacity against two different diseases on wheat. Biocontrol efficacies results in both greenhouse and field tests showed high positive correlation with assessment values (0.720 and 0.806), suggesting that the BCAs screening and assessing strategy previously developed in our lab is also adaptable for conjunctively screening BCAs for controlling both root and shoot diseases on wheat caused by same fungal pathogen. Copyright © 2015 Elsevier GmbH. All rights reserved.

A case of severe soft tissue infection due to Streptococcus tigurinus diagnosed by necropsy in which genomic analysis was useful for clarifying its pathogenicity.

PubMed

Yoshizawa, Hidenori; Motooka, Daisuke; Matsumoto, Yuki; Katada, Ryuichi; Nakamura, Shota; Morii, Eiichi; Iida, Tetsuya; Matsumoto, Hiroshi

2018-05-01

Post-mortem detection of pathogenetic microorganisms in severe infectious death is significantly important for diagnosing the cause of death as well as for public health. However, it is difficult to recognize whether a microorganism detected from post-mortem materials is truly pathogenic or not. We report a case of severe soft tissue infection due to Streptococcus oralis subsp. tigurinus (S. tigurinus), a recently reported species, in which whole-genome analysis was performed to clarify its pathogenicity. A 46-year-old woman had died with symptoms of a severe infectious disease. A post-mortem examination was performed by a medical examiner. The external findings suggested a soft tissue infection; subsequently, pathological specimens sampled by necropsy revealed findings compatible with necrotizing fasciitis. In the post-mortem bacterial test, S. tigurinus was detected from the localized autopsy sample. Whole-genome sequencing was performed to analyze its pathogenicity and detected a strain of S. tigurinus with genetic determinants that were specific and unique to its highly virulent strains as a result of gene annotation. Utilizing various technologies, such as whole-genome sequencing, may be a powerful tool for diagnosing the cause of infectious death accurately and safely. © 2018 Japanese Society of Pathology and John Wiley & Sons Australia, Ltd.

Quantification and characterisation of Trichoderma spp. from different ecosystems.

PubMed

Sariah, M; Choo, C W; Zakaria, H; Norihan, M S

2005-01-01

Basal stem rot of oil palm caused by Ganoderma boninense is of major economic importance. Observations of the low incidence of disease due to Ganoderma species in natural stands, suggest that the disease is kept under control by some biological means. Trichoderma spp. are saprophytic fungi with high antagonistic activities against soil-borne pathogens. However, their abundance and distribution are soil and crop specific. Trichoderma species have been found to be concentrated in the A1 (0-30 cm) and Be soil horizons (30-60 cm), although the abundance of Trichoderma was not significantly different between the oil palm and non-oil palm ecosystems. Characterisation of Trichoderma isolates based on cultural, morphological and DNA polymorphism showed that T. harzianum, T. virens, T. koningii and T. longibrachiatum made up 72, 14, 10 and 4% of the total Trichoderma isolates isolated. As Trichoderma species are present in the oil palm ecosystem, but at lower numbers and in locations different from those desired, soil augmentation with antagonistic Trichoderma spp. can be developed as a strategy towards integrated management of basal stem rot of oil palm.

Salicylic acid treatment reduces the rot of postharvest citrus fruit by inducing the accumulation of H2O2, primary metabolites and lipophilic polymethoxylated flavones.

PubMed

Zhu, Feng; Chen, Jiajing; Xiao, Xue; Zhang, Mingfei; Yun, Ze; Zeng, Yunliu; Xu, Juan; Cheng, Yunjiang; Deng, Xiuxin

2016-09-15

To comprehensively analyze the effects of salicylic acid (SA) on the storability of Satsuma mandarin (Citrus unshiu), fruits were treated with 2mM SA. The disease incidence of control/SA-treated fruit at 50d and 120d after treatment was 23.3%/10% and 67.3%/23.3%, respectively, suggesting that SA treatment can significantly reduce the rot rate of postharvest citrus fruit. Fruit quality assays revealed that the treatment can maintain fruit firmness without affecting the inner quality. Furthermore, the contents of H2O2 and some defense-related metabolites, such as ornithine and threonine, in citrus pericarp, were significantly increased by SA treatment. Moreover, it was lipophilic polymethoxylated flavones, rather than flavanone glycosides, that accumulated in SA-treated fruits and these can directly inhibit pathogen development. These results suggest that the effects of SA on postharvest citrus fruit may be attributed to the accumulation of H2O2 and defense-related metabolites. Copyright © 2016. Published by Elsevier Ltd.

Non Diphtheritic Corynebacteria: An Emerging Nosocomial Pathogen in Skin and Soft Tissue Infection.

PubMed

Rudresh, Shoorashetty Manohar; Ravi, G S; Alex, Ann Mary; Mamatha, K R; Sunitha, L; Ramya, K Thangam

2015-12-01

Non-diphtheritic corynebacteria are normal inhabitants of skin and mucous membrane. When isolated from clinical specimens they are often considered as contaminants. Recent reports suggest their role as emerging nosocomial pathogens. To speciate non-diphtheritic corynebacteria isolated from wound specimens, to correlate their clinical significance and to determine their invitro antimicrobial susceptibilities to 9 antimicrobial agents. Twenty five non-diphtheritic corynebacteria from skin and soft tissue infections were selected for study. Isolates were identified by battery of tests and minimum inhibitory concentration (MIC) was detected by Clinical & Laboratory Standards Institute (CLSI) described broth microdilution method. MIC was interpreted according CLSI and British Society for Antimicrobial Chemotherapy (BSAC) guidelines. C. amycolatum was the predominant species (20%) followed by C. striatum (16%). Penicillin was least effective invitro followed by clindamycin and ciprofloxacin. Excellent activities were shown by vancomycin, linezolid and imipenem. Multidrug resistance was found in all the species. Non-diphtheritic corynebacteria are potential nosocomial pathogens among acute/chronic complicated skin and soft tissue infection. Vancomycin or linezolid can be used empirically to treat such infections until the invitro susceptibility results are available.

Spatial Heterogeneity of SOM Concentrations Associated with White-rot Versus Brown-rot Wood Decay.

PubMed

Bai, Zhen; Ma, Qiang; Dai, Yucheng; Yuan, Haisheng; Ye, Ji; Yu, Wantai

2017-10-23

White- and brown-rot fungal decay via distinct pathways imparts characteristic molecular imprints on decomposing wood. However, the effect that a specific wood-rotting type of fungus has on proximal soil organic matter (SOM) accumulation remains unexplored. We investigated the potential influence of white- and brown-rot fungi-decayed Abies nephrolepis logs on forest SOM stocks (i.e., soil total carbon (C) and nitrogen (N)) and the concentrations of amino sugars (microbial necromass) at different depths and horizontal distances from decaying woody debris. The brown-rot fungal wood decay resulted in higher concentrations of soil C and N and a greater increase in microbial necromass (i.e., 1.3- to 1.7-fold greater) than the white-rot fungal wood decay. The white-rot sets were accompanied by significant differences in the proportions of the bacterial residue index (muramic acid%) with soil depth; however, the brown-rot-associated soils showed complementary shifts, primarily in fungal necromass, across horizontal distances. Soil C and N concentrations were significantly correlated with fungal rather than bacterial necromass in the brown-rot systems. Our findings confirmed that the brown-rot fungi-dominated degradation of lignocellulosic residues resulted in a greater SOM buildup than the white-rot fungi-dominated degradation.

Endophytic fungal diversity in Theobroma cacao (cacao) and T. grandiflorum (cupuaçu) trees and their potential for growth promotion and biocontrol of black-pod disease.

PubMed

Hanada, Rogério Eiji; Pomella, Alan William V; Costa, Heron Salazar; Bezerra, José Luiz; Loguercio, Leandro L; Pereira, José O

2010-01-01

The endophytic niches of plants are a rich source of microbes that can directly and indirectly promote plant protection, growth and development. The diversity of culturable endophytic fungi from stems and branches of Theobroma cacao (cacao) and Theobroma grandiflorum (cupuaçu) trees growing in the Amazon region of Brazil was assessed. The collection of fungal endophytic isolates obtained was applied in field experiments to evaluate their potential as biocontrol agents against Phytophthora palmivora, the causal agent of the black-pod rot disease of cacao, one of the most important pathogens in cocoa-producing regions worldwide. The isolated endophytic fungi from 60 traditional, farmer-planted, healthy cacao and 10 cupuaçu plants were cultured in PDA under conditions inducing sporulation. Isolates were classified based upon the morphological characteristics of their cultures and reproductive structures. Spore suspensions from a total of 103 isolates that could be classified at least up to genus level were tested against P. palmivora in pods attached to cacao trees in the field. Results indicated that ∼70% of isolates showed biocontrol effects to a certain extent, suggesting that culturable endophytic fungal biodiversity in this system is of a mostly mutualistic type of interaction with the host. Eight isolates from genera Trichoderma (reference isolate), Pestalotiopsis, Curvularia, Tolypocladium and Fusarium showed the highest level of activity against the pathogen, and were further characterized. All demonstrated their endophytic nature by colonizing axenic cacao plantlets, and confirmed their biocontrol activity on attached pods trials by showing significant decrease in disease severity in relation to the positive control. None, however, showed detectable growth-promotion effects. Aspects related to endophytic biodiversity and host-pathogen-endophyte interactions in the environment of this study were discussed on the context of developing sustainable strategies for biological control of black-pod rot of cacao. Copyright © 2010 The British Mycological Society. Published by Elsevier Ltd. All rights reserved.

Frank Lamson-Scribner: botanist and pioneer plant pathologist in the United States.

PubMed

Hilty, J W; Peterson, P D

1997-01-01

Frank Lamson-Scribner, in 1885, became the first scientist commissioned by the United States Department of Agriculture with the responsibility to study diseases of economic plants. His innovative approach established the foundation for applied plant pathology at the USDA. In an early international cooperative effort in plant pathology, he detailed the life history of the grape black rot pathogen. His early studies with the Bordeaux mixture introduced the American farmer to the modern era of chemical control. Scribner became the botanist and director of the University of Tennessee Agricultural Experiment Station. He published the first book written on the subject of plant diseases in the United States, and described a new nematode disease of potato. He asserted that the practical value of plant pathology to farmers would only follow meticulous studies of the life history of pathogens.

Phylogeny and comparative genome analysis of a Basidiomycete fungi

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

Riley, Robert W.; Salamov, Asaf; Grigoriev, Igor

2011-03-14

Fungi of the phylum Basidiomycota, make up some 37percent of the described fungi, and are important from the perspectives of forestry, agriculture, medicine, and bioenergy. This diverse phylum includes the mushrooms, wood rots, plant pathogenic rusts and smuts, and some human pathogens. To better understand these important fungi, we have undertaken a comparative genomic analysis of the Basidiomycetes with available sequenced genomes. We report a phylogeny that sheds light on previously unclear evolutionary relationships among the Basidiomycetes. We also define a `core proteome? based on protein families conserved in all Basidiomycetes. We identify key expansions and contractions in protein familiesmore » that may be responsible for the degradation of plant biomass such as cellulose, hemicellulose, and lignin. Finally, we speculate as to the genomic changes that drove such expansions and contractions.« less

Inventory and update on argasid ticks and associated pathogens in Algeria.

PubMed

Lafri, I; Benredjem, W; Neffah-Baaziz, F; Lalout, R; Abdelouahed, K; Gassen, B; Bakhouch, S; Chergui, M; Karakellah, M; Adjmi-Hamoudi, H; Bitam, I

2018-05-01

Argasid ticks include vectors of relapsing fevers caused by Borrelia spp. in humans, and they can transmit arboviruses and other bacterial pathogens. Knowledge about soft ticks ( Ixodida: Argasidae ) in Algeria is incomplete, and distribution data need to be updated. Here we report a series of entomologic investigations that we conducted in five different areas in Algeria between 2012 and 2015. Ticks were identified by entomologic keys and molecular tools (16S rRNA gene). Six distinct species belonging to two genera were identified, including Ornithodoros capensis s.s., Ornithodoros rupestris, Ornithodoros occidentalis, Ornithodoros erraticus, Ornithodoros sonrai and Argas persicus. The present study highlights the distribution of soft ticks, the establishment of an update inventory with nine species and associated pathogens detected in argasid ticks in Algeria.

Spatial Distribution of Root and Crown Rot Fungi Associated With Winter Wheat in the North China Plain and Its Relationship With Climate Variables

PubMed Central

Xu, Fei; Yang, Gongqiang; Wang, Junmei; Song, Yuli; Liu, Lulu; Zhao, Kai; Li, Yahong; Han, Zihang

2018-01-01

The distribution frequency of pathogenic fungi associated with root and crown rot of winter wheat (Triticum aestivum) from 104 fields in the North China Plain was determined during the period from 2013 to 2016. The four most important species identified were Bipolaris sorokiniana (24.0% from roots; 33.7% from stems), Fusarium pseudograminearum (14.9% from roots; 27.8% from stems), Rhizoctonia cerealis (1.7% from roots; 4.4% from stems), and Gaeumannomyces graminis var. tritici (9.8% from roots; 4.4% from stems). We observed that the recovered species varied with the agronomic zone. Fusarium pseudograminearum was predominant in regions 1 and 3, whereas F. graminearum, F. acuminatum, and R. cerealis were predominant in regions 2 and 4. The incidence of F. pseudograminearum and R. cerealis was significantly different between regions 1 and 4, while no significant association was found in the distribution of the other species and the agronomic zones. A negative correlation between the frequency of occurrence of F. pseudograminearum and mean annual precipitation during 2013–2016 (r = −0.71; P < 0.01) in the North China Plain and a positive correlation between the mean annual precipitation during 2013–2016 and the frequency of occurrence of F. asiaticum (r = 0.74; P < 0.01) were observed. Several Fusarium species were also found with low frequencies of ~2.1%−3.4 % (F. graminearum, F. acuminatum, and F. sinensis) and ~0.1%−1.3% (F. equiseti, F. oxysporum, F. proliferatum, F. culmorum, F. avenaceum, and F. asiaticum). In more than 93% of the fields, from the root and crown tissues of wheat, two or more root and crown rot species were isolated. The coexistence of Fusarium spp. and B. sorokiniana in one field (65.4%) or in individual plants (11.6%) was more common than for the other species combinations. Moreover, this is the first report on the association between F. sinensis and root and crown rot of wheat. Our results would be useful in the framing guidelines for the management of root and crown rot fungi in wheat in different agronomic zones of the North China Plain. PMID:29887840

Root rot in sugar beet piles at harvest

USDA-ARS?s Scientific Manuscript database

Sugar beet root rots are not only a concern because of reduced yields, but can also be associated with losses in storage. Our primary sugar beet root rot disease problem in the Amalgamated production area is Rhizoctonia root rot. However, this rot frequently only penetrates a short distance past t...

Evaluation of stem rot in 339 Bornean tree species: implications of size, taxonomy, and soil-related variation for aboveground biomass estimates

NASA Astrophysics Data System (ADS)

Heineman, K. D.; Russo, S. E.; Baillie, I. C.; Mamit, J. D.; Chai, P. P.-K.; Chai, L.; Hindley, E. W.; Lau, B.-T.; Tan, S.; Ashton, P. S.

2015-10-01

Fungal decay of heart wood creates hollows and areas of reduced wood density within the stems of living trees known as stem rot. Although stem rot is acknowledged as a source of error in forest aboveground biomass (AGB) estimates, there are few data sets available to evaluate the controls over stem rot infection and severity in tropical forests. Using legacy and recent data from 3180 drilled, felled, and cored stems in mixed dipterocarp forests in Sarawak, Malaysian Borneo, we quantified the frequency and severity of stem rot in a total of 339 tree species, and related variation in stem rot with tree size, wood density, taxonomy, and species' soil association, as well as edaphic conditions. Predicted stem rot frequency for a 50 cm tree was 53 % of felled, 39 % of drilled, and 28 % of cored stems, demonstrating differences among methods in rot detection ability. The percent stem volume infected by rot, or stem rot severity, ranged widely among trees with stem rot infection (0.1-82.8 %) and averaged 9 % across all trees felled. Tree taxonomy explained the greatest proportion of variance in both stem rot frequency and severity among the predictors evaluated in our models. Stem rot frequency, but not severity, increased sharply with tree diameter, ranging from 13 % in trees 10-30 cm DBH to 54 % in stems ≥ 50 cm DBH across all data sets. The frequency of stem rot increased significantly in soils with low pH and cation concentrations in topsoil, and stem rot was more common in tree species associated with dystrophic sandy soils than with nutrient-rich clays. When scaled to forest stands, the maximum percent of stem biomass lost to stem rot varied significantly with soil properties, and we estimate that stem rot reduces total forest AGB estimates by up to 7 % relative to what would be predicted assuming all stems are composed strictly of intact wood. This study demonstrates not only that stem rot is likely to be a significant source of error in forest AGB estimation, but also that it strongly covaries with tree size, taxonomy, habitat association, and soil resources, underscoring the need to account for tree community composition and edaphic variation in estimating carbon storage in tropical forests.

Sweets for the foe - effects of nonstructural carbohydrates on the susceptibility of Quercus robur against Phytophthora quercina.

PubMed

Angay, Oguzhan; Fleischmann, Frank; Recht, Sabine; Herrmann, Sylvie; Matyssek, Rainer; Oßwald, Wolfgang; Buscot, François; Grams, Thorsten E E

2014-09-01

The root-rot pathogen Phytophthora quercina is a key determinant of oak decline in Europe. The susceptibility of pedunculate oak (Quercus robur) to this pathogen has been hypothesized to depend on the carbon availability in roots as an essential resource for defense. Microcuttings of Q. robur undergo an alternating rhythm of root and shoot growth. Inoculation of mycorrhizal (Piloderma croceum) and nonmycorrhizal oak roots with P. quercina was performed during both growth phases, that is, root flush (RF) and shoot flush (SF). Photosynthetic and morphological responses as well as concentrations of nonstructural carbohydrates (NSC) were analyzed. Infection success was quantified by the presence of pathogen DNA in roots. Concentrations of NSC in roots depended on the alternating root/shoot growth rhythm, being high and low during RF and SF, respectively. Infection success was high during RF and low during SF, resulting in a significantly positive correlation between pathogen DNA and NSC concentration in roots, contrary to the hypothesis. The alternating growth of roots and shoots plays a crucial role for the susceptibility of lateral roots to the pathogen. NSC availability in oak roots has to be considered as a benchmark for susceptibility rather than resistance against P. quercina. © 2014 The Authors. New Phytologist © 2014 New Phytologist Trust.

Over-expression of the Pseudomonas syringae harpin-encoding gene hrpZm confers enhanced tolerance to Phytophthora root and stem rot in transgenic soybean.

PubMed

Du, Qian; Yang, Xiangdong; Zhang, Jinhua; Zhong, Xiaofang; Kim, Kyung Seok; Yang, Jing; Xing, Guojie; Li, Xiaoyu; Jiang, Zhaoyuan; Li, Qiyun; Dong, Yingshan; Pan, Hongyu

2018-06-01

Phytophthora root and stem rot (PRR) caused by Phytophthora sojae is one of the most devastating diseases reducing soybean (Glycine max) production all over the world. Harpin proteins in many plant pathogenic bacteria were confirmed to enhance disease and insect resistance in crop plants. Here, a harpin protein-encoding gene hrpZpsta from the P. syringae pv. tabaci strain Psta218 was codon-optimized (renamed hrpZm) and introduced into soybean cultivars Williams 82 and Shennong 9 by Agrobacterium-mediated transformation. Three independent transgenic lines over-expressing hrpZm were obtained and exhibited stable and enhanced tolerance to P. sojae infection in T 2 -T 4 generations compared to the non-transformed (NT) and empty vector (EV)-transformed plants. Quantitative real-time PCR (qRT-PCR) analysis revealed that the expression of salicylic acid-dependent genes PR1, PR12, and PAL, jasmonic acid-dependent gene PPO, and hypersensitive response (HR)-related genes GmNPR1 and RAR was significantly up-regulated after P. sojae inoculation. Moreover, the activities of defense-related enzymes such as phenylalanine ammonia lyase (PAL), polyphenoloxidase (PPO), peroxidase, and superoxide dismutase also increased significantly in the transgenic lines compared to the NT and EV-transformed plants after inoculation. Our results suggest that over-expression of the hrpZm gene significantly enhances PRR tolerance in soybean by eliciting resistance responses mediated by multiple defense signaling pathways, thus providing an alternative approach for development of soybean varieties with improved tolerance against the soil-borne pathogen PRR.

Composts containing fluorescent pseudomonads suppress fusarium root and stem rot development on greenhouse cucumber.

PubMed

Bradley, Geoffrey G; Punja, Zamir K

2010-11-01

Three composts (Ball, dairy, and greenhouse) were tested for the ability to suppress the development of Fusarium root and stem rot (caused by Fusarium oxysporum f. sp. radicis-cucumerinum) on greenhouse cucumber. Dairy and greenhouse composts significantly reduced disease severity (P = 0.05), while Ball compost had no effect. Assessment of total culturable microbes in the composts showed a positive relationship between disease suppressive ability and total population levels of pseudomonads. In vitro antagonism assays between compost-isolated bacterial strains and the pathogen showed that strains of Pseudomonas aeruginosa exhibited the greatest antagonism. In growth room trials, strains of P. aeruginosa and nonantagonistic Pseudomonas maculicola, plus 2 biocontrol strains of Pseudomonas fluorescens, were tested for their ability to reduce (i) survival of F. oxysporum, (ii) colonization of plants by the pathogen, and (iii) disease severity. Cucumber seedlings grown in compost receiving P. aeruginosa and P. fluorescens had reduced disease severity index scores after 8 weeks compared with control plants without bacteria. Internal stem colonization by F. oxysporum was significantly reduced by P. aeruginosa. The bacteria colonized plant roots at 1.9 × 10(6) ± 0.73 × 10(6) CFU·(g root tissue)-1 and survival was >107 CFU·(g compost)-1 after 6 weeks. The locus for 2,4-diacetylphloroglucinol production was detected by Southern blot analysis and confirmed by PCR. The production of the antibiotic 2,4-diacetylphloroglucinol in liquid culture by P. aeruginosa was confirmed by thin layer chromatography. These results demonstrate that composts containing antibiotic-producing P. aeruginosa have the potential to suppress diseases caused by Fusarium species.

Production of Lytic Enzymes by Trichoderma Isolates during in vitro Antagonism with Aspergillus Niger, The Causal Agent of Collar ROT of Peanut

PubMed Central

Gajera, H. P.; Vakharia, D. N.

2012-01-01

Twelve isolates of Trichoderma (six of T. harzianum, five of T. viride, one of T. virens), which reduced variably the incidence of collar rot disease caused in peanut by Aspergillus niger Van Tieghem, were evaluated for their potential to produce lytic enzymes during in vitro antagonism. T. viride 60 inhibited highest (86.2%) growth of test fungus followed by T. harzianum 2J (80.4%) at 6 days after inoculation (DAI) on PDA media. The specific activities of chitinase, β-1,3-glucanase and protease were 11, 3.46 and 9 folds higher in T6 antagonist (T. viride 60 and A. niger interactions) followed by 8.72, 2.85 and 9 folds in T8antagonist (T. harzianum 2J and A. niger interactions), respectively, compared to the activity produced by control petri plate T13 (A. niger alone) at 6 DAI. Activity of these lytic enzymes induced in antagonists’ plates comprises the growth of Trichoderma isolates. However, cellulase and poly galacturonase were found least amount in these antagonists treatment. A significant positive correlation (p=0.01) between percentage growth inhibition of test fungus and lytic enzymes – (chitinase, β-1,3-glucanase and protease) in the culture medium of antagonist treatment established a relationship to inhibit growth of fungal pathogen by increasing the levels of these enzymes. Among the Trichoderma isolates, T. viride 60 was found best strain to be used in biological control of plant pathogen A. niger. PMID:24031802

Effects of Water Stress on the Endophytic Fungal Communities of Pinus koraiensis Needles Infected by Cenangium ferruginosum

PubMed Central

Lee, Sun Keun; Lee, Seung Kyu; Bae, Hanhong; Seo, Sang-Tae

2014-01-01

To examine the effects of water stress and Cenangium ferruginosum (CF) on the fungal endophytic community of needles of Pinus koraiensis (PK), fungal endophytes isolated from the needles of 5-year-old PK seedlings were compared before and after exposure to water stress conditions and artificial inoculation with CF ascospores. Artificial CF inoculation was successfully confirmed using PCR with CF-specific primers (CfF and CfR). For comparison of the degree of water deficit in water-stressed and control groups of PK seedlings infected with CF, the water saturation deficit and water potential were measured. Lower water potential estimates were found in the water-stressed seedlings than in the control group. The fungal endophytes isolated from the second-year needles of non-water-stressed seedlings before and after CF inoculation revealed that primary saprobes were approximately 30% and 71.7%, respectively, and the remaining endophytes were rot fungi or pathogens. Sixty days after CF inoculation, diverse fungal endophytes in the first-year needles were isolated from the water-stressed seedlings. However, some fungal endophytes isolated from the non-water-stressed seedlings were also identified. Fungal endophytes in the second-year needles of the water-stressed and non-water-stressed seedlings were approximately 8% and 71.7% of saprobes, respectively, and the remaining endophytes were rot fungi or pathogens. On the basis of the results, we conclude that water deficit and CF can have an effect on fungal endophytic communities in the needles of PK seedlings. PMID:25606004

Multiple Multi-Copper Oxidase Gene Families in Basidiomycetes – What for?

PubMed Central

Kües, Ursula; Rühl, Martin

2011-01-01

Genome analyses revealed in various basidiomycetes the existence of multiple genes for blue multi-copper oxidases (MCOs). Whole genomes are now available from saprotrophs, white rot and brown rot species, plant and animal pathogens and ectomycorrhizal species. Total numbers (from 1 to 17) and types of mco genes differ between analyzed species with no easy to recognize connection of gene distribution to fungal life styles. Types of mco genes might be present in one and absent in another fungus. Distinct types of genes have been multiplied at speciation in different organisms. Phylogenetic analysis defined different subfamilies of laccases sensu stricto (specific to Agaricomycetes), classical Fe2+-oxidizing Fet3-like ferroxidases, potential ferroxidases/laccases exhibiting either one or both of these enzymatic functions, enzymes clustering with pigment MCOs and putative ascorbate oxidases. Biochemically best described are laccases sensu stricto due to their proposed roles in degradation of wood, straw and plant litter and due to the large interest in these enzymes in biotechnology. However, biological functions of laccases and other MCOs are generally little addressed. Functions in substrate degradation, symbiontic and pathogenic intercations, development, pigmentation and copper homeostasis have been put forward. Evidences for biological functions are in most instances rather circumstantial by correlations of expression. Multiple factors impede research on biological functions such as difficulties of defining suitable biological systems for molecular research, the broad and overlapping substrate spectrum multi-copper oxidases usually possess, the low existent knowledge on their natural substrates, difficulties imposed by low expression or expression of multiple enzymes, and difficulties in expressing enzymes heterologously. PMID:21966246

Phytophthora megakarya and Phytophthora palmivora, Closely Related Causal Agents of Cacao Black Pod Rot, Underwent Increases in Genome Sizes and Gene Numbers by Different Mechanisms

PubMed Central

Ali, Shahin S.; Shao, Jonathan; Lary, David J.; Kronmiller, Brent A.; Shen, Danyu; Strem, Mary D.; Amoako-Attah, Ishmael; Akrofi, Andrew Yaw; Begoude, B.A. Didier; ten Hoopen, G. Martijn; Coulibaly, Klotioloma; Kebe, Boubacar Ismaël; Melnick, Rachel L.; Guiltinan, Mark J.; Tyler, Brett M.; Meinhardt, Lyndel W.

2017-01-01

Phytophthora megakarya (Pmeg) and Phytophthora palmivora (Ppal) are closely related species causing cacao black pod rot. Although Ppal is a cosmopolitan pathogen, cacao is the only known host of economic importance for Pmeg. Pmeg is more virulent on cacao than Ppal. We sequenced and compared the Pmeg and Ppal genomes and identified virulence-related putative gene models (PGeneM) that may be responsible for their differences in host specificities and virulence. Pmeg and Ppal have estimated genome sizes of 126.88 and 151.23 Mb and PGeneM numbers of 42,036 and 44,327, respectively. The evolutionary histories of Pmeg and Ppal appear quite different. Postspeciation, Ppal underwent whole-genome duplication whereas Pmeg has undergone selective increases in PGeneM numbers, likely through accelerated transposable element-driven duplications. Many PGeneMs in both species failed to match transcripts and may represent pseudogenes or cryptic genetic reservoirs. Pmeg appears to have amplified specific gene families, some of which are virulence-related. Analysis of mycelium, zoospore, and in planta transcriptome expression profiles using neural network self-organizing map analysis generated 24 multivariate and nonlinear self-organizing map classes. Many members of the RxLR, necrosis-inducing phytophthora protein, and pectinase genes families were specifically induced in planta. Pmeg displays a diverse virulence-related gene complement similar in size to and potentially of greater diversity than Ppal but it remains likely that the specific functions of the genes determine each species’ unique characteristics as pathogens. PMID:28186564

Detection of a novel Rickettsia sp. in soft ticks (Acari: Argasidae) in Algeria.

PubMed

Lafri, Ismail; Leulmi, Hamza; Baziz-Neffah, Fadhila; Lalout, Reda; Mohamed, Chergui; Mohamed, Karakallah; Parola, Philippe; Bitam, Idir

2015-01-01

Argasid ticks are vectors of viral and bacterial agents that can infect humans and animals. In Africa, relapsing fever borreliae are neglected arthropod-borne pathogens that cause mild to deadly septicemia and miscarriage. It would be incredibly beneficial to be able to simultaneous detect and identify other pathogens transmitted by Argasid ticks. From 2012 to 2014, we conducted field surveys in 4 distinct areas of Algeria. We investigated the occurrence of soft ticks in rodent burrows and yellow-legged gull (Larus michahellis) nests in 10 study sites and collected 154 soft ticks. Molecular identification revealed the occurrence of two different soft tick genera and five species, including Carios capensis in yellow-legged gull nests and Ornithodoros occidentalis, Ornithodoros rupestris, Ornithodoros sonrai, Ornithodoros erraticus in rodent burrows. Rickettsial DNA was detected in 41/154, corresponding to a global detection rate of 26.6%. Sequences of the citrate synthase (gltA) gene suggest that this agent is a novel spotted fever group Rickettsia. For the first time in Algeria, we characterize a novel Rickettsia species by molecular means in soft ticks. Copyright © 2015 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

Root rots

Treesearch

Kathryn Robbins; Philip M. Wargo

1989-01-01

Root rots of central hardwoods are diseases caused by fungi that infect and decay woody roots and sometimes also invade the butt portion of the tree. By killing and decaying roots, root rotting fungi reduce growth, decrease tree vigor, and cause windthrow and death. The most common root diseases of central hardwoods are Armillaria root rot, lnonotus root rot, and...

Identification and characterization of LysM effectors in Penicillium expansum.

PubMed

Levin, Elena; Ballester, Ana Rosa; Raphael, Ginat; Feigenberg, Oleg; Liu, Yongsheng; Norelli, John; Gonzalez-Candelas, Luis; Ma, Jing; Dardick, Christopher; Wisniewski, Michael; Droby, Samir

2017-01-01

P. expansum is regarded as one of the most important postharvest rots of apple fruit and is also of great concern to fruit processing industries. Elucidating the pathogenicity mechanism of this pathogen is of utmost importance for the development of effective and safe management strategies. Although, many studies on modification of the host environment by the pathogen were done, its interactions with fruit during the early stages of infection and the virulence factors that mediate pathogenicity have not been fully defined. Effectors carrying LysM domain have been identified in numerous pathogenic fungi and their role in the first stages of infection has been established. In this study, we identified 18 LysM genes in the P. expansum genome. Amino acid sequence analysis indicated that P. expansum LysM proteins belong to a clade of fungal-specific LysM. Eleven of the discovered LysM genes were found to have secretory pathway signal peptide, among them, 4 (PeLysM1 PeLysM2, PeLysM3 and PeLysM4) were found to be highly expressed during the infection and development of decay of apple fruit. Effect of targeted deletion of the four putative PeLysM effectors on the growth and pathogenicity was studied. Possible interactions of PeLysM with host proteins was investigated using the yeast-two-hybrid system.

Pantoea ananatis Genetic Diversity Analysis Reveals Limited Genomic Diversity as Well as Accessory Genes Correlated with Onion Pathogenicity.

PubMed

Stice, Shaun P; Stumpf, Spencer D; Gitaitis, Ron D; Kvitko, Brian H; Dutta, Bhabesh

2018-01-01

Pantoea ananatis is a member of the family Enterobacteriaceae and an enigmatic plant pathogen with a broad host range. Although P. ananatis strains can be aggressive on onion causing foliar necrosis and onion center rot, previous genomic analysis has shown that P. ananatis lacks the primary virulence secretion systems associated with other plant pathogens. We assessed a collection of fifty P. ananatis strains collected from Georgia over three decades to determine genetic factors that correlated with onion pathogenic potential. Previous genetic analysis studies have compared strains isolated from different hosts with varying diseases potential and isolation sources. Strains varied greatly in their pathogenic potential and aggressiveness on different cultivated Allium species like onion, leek, shallot, and chive. Using multi-locus sequence analysis (MLSA) and repetitive extragenic palindrome repeat (rep)-PCR techniques, we did not observe any correlation between onion pathogenic potential and genetic diversity among strains. Whole genome sequencing and pan-genomic analysis of a sub-set of 10 strains aided in the identification of a novel series of genetic regions, likely plasmid borne, and correlating with onion pathogenicity observed on single contigs of the genetic assemblies. We named these loci Onion Virulence Regions (OVR) A-D. The OVR loci contain genes involved in redox regulation as well as pectate lyase and rhamnogalacturonase genes. Previous studies have not identified distinct genetic loci or plasmids correlating with onion foliar pathogenicity or pathogenicity on a single host pathosystem. The lack of focus on a single host system for this phytopathgenic disease necessitates the pan-genomic analysis performed in this study.

Pantoea ananatis Genetic Diversity Analysis Reveals Limited Genomic Diversity as Well as Accessory Genes Correlated with Onion Pathogenicity

PubMed Central

Stice, Shaun P.; Stumpf, Spencer D.; Gitaitis, Ron D.; Kvitko, Brian H.; Dutta, Bhabesh

2018-01-01

Pantoea ananatis is a member of the family Enterobacteriaceae and an enigmatic plant pathogen with a broad host range. Although P. ananatis strains can be aggressive on onion causing foliar necrosis and onion center rot, previous genomic analysis has shown that P. ananatis lacks the primary virulence secretion systems associated with other plant pathogens. We assessed a collection of fifty P. ananatis strains collected from Georgia over three decades to determine genetic factors that correlated with onion pathogenic potential. Previous genetic analysis studies have compared strains isolated from different hosts with varying diseases potential and isolation sources. Strains varied greatly in their pathogenic potential and aggressiveness on different cultivated Allium species like onion, leek, shallot, and chive. Using multi-locus sequence analysis (MLSA) and repetitive extragenic palindrome repeat (rep)-PCR techniques, we did not observe any correlation between onion pathogenic potential and genetic diversity among strains. Whole genome sequencing and pan-genomic analysis of a sub-set of 10 strains aided in the identification of a novel series of genetic regions, likely plasmid borne, and correlating with onion pathogenicity observed on single contigs of the genetic assemblies. We named these loci Onion Virulence Regions (OVR) A-D. The OVR loci contain genes involved in redox regulation as well as pectate lyase and rhamnogalacturonase genes. Previous studies have not identified distinct genetic loci or plasmids correlating with onion foliar pathogenicity or pathogenicity on a single host pathosystem. The lack of focus on a single host system for this phytopathgenic disease necessitates the pan-genomic analysis performed in this study. PMID:29491851

Response of the Andean diversity panel to root rot in a root rot nursery in Puerto Rico

USDA-ARS?s Scientific Manuscript database

The Andean Diversity Panel (ADP) was evaluated under low-fertility and root rot conditions in two trials conducted in 2013 and 2015 in Isabela, Puerto Rico. About 246 ADP lines were evaluated in the root rot nursery with root rot and stem diseases caused predominantly by Fusarium solani, which cause...

Multiple garlic (Allium sativum L.) microRNAs regulate the immunity against the basal rot fungus Fusarium oxysporum f. sp. Cepae.

PubMed

Chand, Subodh Kumar; Nanda, Satyabrata; Mishra, Rukmini; Joshi, Raj Kumar

2017-04-01

The basal plate rot fungus, Fusarium oxysporum f. sp. cepae (FOC), is the most devastating pathogen posing a serious threat to garlic (Allium sativum L.) production worldwide. MicroRNAs (miRNAs) are key modulators of gene expression related to development and defense responses in eukaryotes. However, the miRNA species associated with garlic immunity against FOC are yet to be explored. In the present study, a small RNA library developed from FOC infected resistant garlic line was sequenced to identify immune responsive miRNAs. Forty-five miRNAs representing 39 conserved and six novel sequences responsive to FOC were detected. qRT-PCR analyses further classified them into three classes based on their expression patterns in susceptible line CBT-As11 and in the resistant line CBT-As153. North-blot analyses of six selective miRNAs confirmed the qRT-PCR results. Expression studies on a selective set of target genes revealed a negative correlation with the complementary miRNAs. Furthermore, transgenic garlic plant overexpresing miR164a, miR168a and miR393 showed enhanced resistance to FOC, as revealed by decreased fungal growth and up-regulated expression of defense-responsive genes. These results indicate that multiple miRNAs are involved in garlic immunity against FOC and that the overexpression of miR164a, miR168a and miR393 can augment garlic resistance to Fusarium basal rot infection. Copyright © 2017 Elsevier B.V. All rights reserved.

Transcriptome profiling of two maize inbreds with distinct responses to Gibberella ear rot disease to identify candidate resistance genes.

PubMed

Kebede, Aida Z; Johnston, Anne; Schneiderman, Danielle; Bosnich, Whynn; Harris, Linda J

2018-02-09

Gibberella ear rot (GER) is one of the most economically important fungal diseases of maize in the temperate zone due to moldy grain contaminated with health threatening mycotoxins. To develop resistant genotypes and control the disease, understanding the host-pathogen interaction is essential. RNA-Seq-derived transcriptome profiles of fungal- and mock-inoculated developing kernel tissues of two maize inbred lines were used to identify differentially expressed transcripts and propose candidate genes mapping within GER resistance quantitative trait loci (QTL). A total of 1255 transcripts were significantly (P ≤ 0.05) up regulated due to fungal infection in both susceptible and resistant inbreds. A greater number of transcripts were up regulated in the former (1174) than the latter (497) and increased as the infection progressed from 1 to 2 days after inoculation. Focusing on differentially expressed genes located within QTL regions for GER resistance, we identified 81 genes involved in membrane transport, hormone regulation, cell wall modification, cell detoxification, and biosynthesis of pathogenesis related proteins and phytoalexins as candidate genes contributing to resistance. Applying droplet digital PCR, we validated the expression profiles of a subset of these candidate genes from QTL regions contributed by the resistant inbred on chromosomes 1, 2 and 9. By screening global gene expression profiles for differentially expressed genes mapping within resistance QTL regions, we have identified candidate genes for gibberella ear rot resistance on several maize chromosomes which could potentially lead to a better understanding of Fusarium resistance mechanisms.

Antagonistic activity of endo-β-1,3-glucanase from a novel isolate, Streptomyces sp. 9X166, against black rot in orchids.

PubMed

Sakdapetsiri, Chatsuda; Fukuta, Yasuhisa; Aramsirirujiwet, Yaovapa; Shirasaka, Norifumi; Kitpreechavanich, Vichien

2016-05-01

A total of 123 actinomycetes was isolated from 12 varieties of wild orchids and screened for potential antagonistic activity against Phytophthora, which causes black rot disease in orchids. In vitro and in vivo experimental results revealed that Streptomyces sp. strain 9X166 showed the highest antagonistic activity; its β-1,3-glucanase production ability was a key mechanism for growth inhibition of the pathogen. PCR amplification and DNA sequencing of the 16S ribosomal RNA gene allowed the identification of this strain, with high similarity (99.93%) to the novel species Streptomyces similaensis. The glucanase enzyme, purified to homogeneity by anion exchange and gel filtration chromatography, showed a specific activity of 58 U mg(-1) (a 3.9-fold increase) and yield of 6.4%. The molecular weight, as determined by SDS-PAGE and gel filtration, was approximately 99 and 80 kDa, respectively, suggesting that the enzyme was a monomer. The purified enzyme showed the highest substrate specificity to laminarin, indicating that it was β-1,3-glucanase. The hydrolyzed products of cello-oligosaccharides suggested that this enzyme was endo-type β-1,3-glucanase. Streptomyces sp. 9X166 culture filtrate, possessing β-1,3-glucanase activity, could degrade both freeze-dried and living mycelium. This is the first report on a β-1,3-glucanase-producing Streptomyces sp. that could be an effective biocontrol agent for black rot disease in orchids. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Aquatic Pseudomonads Inhibit Oomycete Plant Pathogens of Glycine max

PubMed Central

Wagner, Andrew; Norris, Stephen; Chatterjee, Payel; Morris, Paul F.; Wildschutte, Hans

2018-01-01

Seedling root rot of soybeans caused by the host-specific pathogen Phytophthora sojae, and a large number of Pythium species, is an economically important disease across the Midwest United States that negatively impacts soybean yields. Research on biocontrol strategies for crop pathogens has focused on compounds produced by microbes from soil, however, recent studies suggest that aquatic bacteria express distinct compounds that efficiently inhibit a wide range of pathogens. Based on these observations, we hypothesized that freshwater strains of pseudomonads might be producing novel antagonistic compounds that inhibit the growth of oomycetes. To test this prediction, we utilized a collection of 330 Pseudomonas strains isolated from soil and freshwater habitats, and determined their activity against a panel of five oomycetes: Phytophthora sojae, Pythium heterothalicum, Pythium irregulare, Pythium sylvaticum, and Pythium ultimum, all of which are pathogenic on soybeans. Among the bacterial strains, 118 exhibited antagonistic activity against at least one oomycete species, and 16 strains were inhibitory to all pathogens. Antagonistic activity toward oomycetes was significantly more common for aquatic isolates than for soil isolates. One water-derived strain, 06C 126, was predicted to express a siderophore and exhibited diverse antagonistic profiles when tested on nutrient rich and iron depleted media suggesting that more than one compound was produced that effectively inhibited oomycetes. These results support the concept that aquatic strains are an efficient source of compounds that inhibit pathogens. We outline a strategy to identify other strains that express unique compounds that may be useful biocontrol agents. PMID:29896163

Quarantine of Aeromonas salmonicida-harboring ebonyshell mussels (Fusconaia ebena) prevents transmission of the pathogen to brook trout (Salvelinus fontinalis)

USGS Publications Warehouse

Starliper, C.E.

2005-01-01

Furunculosis, caused by the bacterium Aeromonas salmonicida, was artificially induced in brook trout (Salvelinus fontinalis) in an experimental tank. Ebonyshells (Fusconaia ebena) were placed to cohabit with these fish to acquire the pathogen through siphoning. After 2 wk of cohabitation, 10 of the mussels were assayed by bacterial culture and all were found to harbor A. salmonicida. The mean cell count from soft tissue homogenates was 1.84 ?? 105 cfu/g, which comprised an average 14.41% of the total bacteria isolated from tissues. From the fluids, a mean of 2.84 ?? 105 A. salmonicida cfu/mL was isolated, which comprised an average of 17.29% of the total bacterial flora. The mussels were removed from the cohabitation tank and distributed equally among five previously disinfected tanks, 35 per tank. The F. ebena in each tank were allowed to depurate A. salmonicida for various durations: 1, 5, 10, 15 or 30 days. After each group had depurated for their assigned time, 10 were assayed for bacteria, tank water was tested, and 20 pathogen-free bioindicator brook trout were added to cohabit with the remaining mussels. Depuration was considered successful if A. salmonicida was not isolated from tank water or the mussels, and there was no infection or mortality to bioindicator fish. After 1 day of depuration, A. salmonicida was not isolated from the soft tissues; however, it was isolated from one of the paired fluids (10% prevalence). The tank water tested positive, and the bioindicator fish became infected and died. From the 5-day depuration group, A. salmonicida was not isolated from soft tissues, but was isolated from three fluids (30%; mean = 1.56 ?? 102 cfu/mL). Tank water from the 5-day group was negative, and there was no mortality among the bioindicator fish. However, A. salmonicida was isolated from 2 of 20 fish at the end of the 14-day observation period. One F. ebena fluid sample was positive for A. salmonicida from the 10-day depuration group, but none of the soft tissue homogenates. The pathogen was not isolated from 10-day tank water, but there was a 30% cumulative mortality to the bioindicator fish. Aeromonas salmonicida was not isolated from any of the soft tissue homogenates, fluids or tank water from the 15 day or 30 day depuration groups, and the bioindicator fish remained pathogen- and disease-free. Study results showed that the F. ebena were harboring a high A. salmonicida cell load going into depuration, but at 15 days and beyond, the pathogen had been depurated to the extent that the mussels did not serve as pathogen vectors.

Evidence from Serpula lacrymans that 2,5-Dimethoxyhydroquinone Is a Lignocellulolytic Agent of Divergent Brown Rot Basidiomycetes

Treesearch

Premsagar Korripally; Vitaliy I. Timokhin; Carl J. Houtman; Michael D. Mozuch; Kenneth E. Hammel

2013-01-01

Basidiomycetes that cause brown rot of wood are essential biomass recyclers in coniferous forest ecosystems and a major cause of failure in wooden structures. Recent work indicates that distinct lineages of brown rot fungi have arisen independently from ligninolytic white rot ancestors via loss of lignocellulolytic enzymes. Brown rot thus proceeds without significant...

Control of black walnut root rot diseases in nurseries.

Treesearch

Kenneth J. Jr. Kessler

1982-01-01

Current nursery methods used to control black walnut root rot diseases are considered in terms of integrated pest management. Suggestions for future root rot control research studies and procedures to minimize root rot problems are provided.

Severe soft tissue infections.

PubMed

Napolitano, Lena M

2009-09-01

Severe skin and soft tissue infections (SSTIs) frequently require management in the ICU, in part related to associated septic shock or toxic shock syndrome or associated organ failure. Four fundamental management principles are key to a successful outcome in caring for patients who have severe SSTIs, including (1) early diagnosis and differentiation of necrotizing versus nonnecrotizing SSTI, (2) early initiation of appropriate empiric broad-spectrum antimicrobial therapy with consideration of risk factors for specific pathogens and mandatory coverage for methicillin-resistant Staphylococcus aureus (MRSA), (3) source control (ie, early aggressive surgical intervention for drainage of abscesses and debridement of necrotizing soft tissue infections), and (4) pathogen identification and appropriate de-escalation of antimicrobial therapy. MRSA has emerged as the most common identifiable cause of severe SSTIs; therefore, initiation of empiric anti-MRSA antimicrobials is warranted in all cases of severe SSTIs. In addition, appropriate critical care management-including fluid resuscitation, organ support and nutritional support-is a necessary component in treating severe SSTIs.

Detection of bacterial infection of agave plants by laser-induced fluorescence

NASA Astrophysics Data System (ADS)

Cervantes-Martinez, Jesus; Flores-Hernandez, Ricardo; Rodriguez-Garay, Benjamin; Santacruz-Ruvalcaba, Fernando

2002-05-01

Greenhouse-grown plants of Agave tequilana Weber var. azul were inoculated with Erwinia carotovora, the causal agent of stem soft rot. We investigated the laser-induced fluorescence (LIF) of agave plants to determine whether LIF can be used as a noninvasive sensing tool for pathological studies. The LIF technique was also investigated as a means of detecting the effect of the polyamine biosynthesis inhibitor beta-hydroxyethylhydrazine as a bactericide against the pathogenic bacterium Erwinia carotovora. A He-Ne laser at 632.8 nm was used as the excitation source, and in vivo fluorescence emission spectra were recorded in the 660-790-range. Fluorescence maxima were at 690 and 740 nm. The infected plants that were untreated with the bactericide showed a definite increase in fluorescence intensity at both maxima within the first three days after infection. Beginning on the fifth day, a steady decrease in fluorescence intensity was observed, with a greater effect at 740 than at 690 nm. After 30 days there was no fluorescence. The infected plants that had been treated with the bactericide showed no significant change in fluorescence compared with that of the uninfected plants. The ratio of fluorescence intensities was determined to be F 690 nm/F 740 nm for all treatments. These studies indicate that LIF measurements of agave plants may be used for the early detection of certain types of disease and for determining the effect of a bactericide on bacteria. The results also showed that fluorescence intensity ratios can be used as a reliable indicator of the progress of disease.

Detection of bacterial infection of agave plants by laser-induced fluorescence.

PubMed

Cervantes-Martínez, Jesús; Flores-Hernández, Ricardo; Rodríguez-Garay, Benjamin; Santacruz-Ruvalcaba, Fernando

2002-05-01

Greenhouse-grown plants of Agave tequilana Weber var. azul were inoculated with Erwinia carotovora, the causal agent of stem soft rot. We investigated the laser-induced fluorescence (LIF) of agave plants to determine whether LIF can be used as a noninvasive sensing tool for pathological studies. The LIF technique was also investigated as a means of detecting the effect of the polyamine biosynthesis inhibitor beta-hydroxyethylhydrazine as a bactericide against the pathogenic bacterium Erwinia carotovora. A He-Ne laser at 632.8 nm was used as the excitation source, and in vivo fluorescence emission spectra were recorded in the 660-790-range. Fluorescence maxima were at 690 and 740 nm. The infected plants that were untreated with the bactericide showed a definite increase in fluorescence intensity at both maxima within the first three days after infection. Beginning on the fifth day, a steady decrease in fluorescence intensity was observed, with a greater effect at 740 than at 690 nm. After 30 days there was no fluorescence. The infected plants that had been treated with the bactericide showed no significant change in fluorescence compared with that of the uninfected plants. The ratio of fluorescence intensities was determined to be F 690 nm/F 740 nm for all treatments. These studies indicate that LIF measurements of agave plants may be used for the early detection of certain types of disease and for determining the effect of a bactericide on bacteria. The results also showed that fluorescence intensity ratios can be used as a reliable indicator of the progress of disease.

The regulation of virulence in phytopathogenic Erwinia species: quorum sensing, antibiotics and ecological considerations.

PubMed

Whitehead, Neil A; Byers, Joseph T; Commander, Paul; Corbett, Mark J; Coulthurst, Sarah J; Everson, Lee; Harris, Abigail K P; Pemberton, Clare L; Simpson, Natalie J L; Slater, Holly; Smith, Debra S; Welch, Martin; Williamson, Neil; Salmond, George P C

2002-08-01

Erwinia carotovora is a Gram-negative bacterial phytopathogen that causes soft-rot disease and potato blackleg. The organism is environmentally widespread and exhibits an opportunistic plant pathogenesis. The ability to secrete multiple plant cell wall-degrading enzymes is a key virulence trait and exoenzyme production is responsive to multiple environmental and physiological cues. One important cue is the cell population density of the pathogen. Cell density is monitored via an acylated homoserine lactone (acyl HSL) signalling molecule, which is thought to diffuse between Erwinia cells in a process now commonly known as 'quorum sensing'. This molecule also acts as the chemical communication signal controlling production of a broad-spectrum beta-lactam antibiotic (1-carbapen-2-em-3-carboxylic acid; carbapenem) synthesised in concert with exoenzyme elaboration, possibly for niche defence. In antibiotic production control, quorum sensing acts at the level of transcriptional activation of the antibiotic biosynthetic cluster. This is achieved via a dedicated LuxR-type protein, CarR that is bound to the signalling molecule. The molecular relay connecting acyl HSL production and exoenzyme induction is not clear, despite the identification of a multitude of global regulatory genes, including those of the RsmA/rsmB system, impinging on enzyme synthesis. Quorum sensing control mediated by acyl HSLs is widespread in Gram-negative bacteria and is responsible for the regulation of diverse phenotypes. Although there is still a paucity of meaningful information on acyl HSL availability and in-situ biological function, there is growing evidence that such molecules play significant roles in microbial ecology.

Oils extracted from Eupatorium adenophorum leaves show potential to control Phythium myriotylum in commercially-grown ginger

PubMed Central

Liu, Xiaoman; Yan, Dongdong; Ouyang, Canbin; Yang, Dongsheng; Wang, Qiuxia; Li, Yuan; Guo, Meixia; Cao, Aocheng

2017-01-01

Oils extracted from the leaves of Eupatorium adenophorum were tested in vitro and in vivo against the soilborne pathogen Pythium myriotylum which causes soft rot, a devastating disease of commercial ginger production in China. Twelve compounds accounting for 99.15% of the total oil composition were identified by GC-MS. The major components were 10Hβ-9-oxo-agerophorone (37.03%), 10Hα-9-oxo-agerophorone (37.73%) and 9-oxo-10, 11-dehydro-agerophorone (23.41%). Antifungal activity was tested by the poisoned food technique against P. myriotylum, indicating minimum inhibitory concentrations of 100μg/ml after 7 days incubation. In addition, the oil extracts greatly inhibited the formation of both wet and dry mycelial biomass. The combination of E. adenophorum oil extracts and synthetic fungicides showed a strong synergistic effect, inhibiting the mycelial growth in in vitro assays. The synergistic effect of oil extracts with fungicides could allow fungicides to be used at reduced rates in the future which has environmental advantages. Oil extracts applied at 160 and 200μg/ml concentrations to ginger rhizomes before inoculation with P. myriotylum significantly reduced the infection rate in ginger. Examination by light and transmission electron microscopy revealed that oil extracts caused swelling of the hyphae, disruption of the cell wall, degradation of the cytoplasmic organelles and shortening of the cytoplasmic inclusion. These results suggested that the plasma membrane and endomembrane systems of P. myriotylum were severely damaged by the oil extracts of E. adenophorum which offer significant potential for use as a fungicide to control P. myriotylum. PMID:28467445

Pyramiding Sclerotinia head rot and stalk rot resistances into elite sunflower breeding lines with the aid of DNA markers

USDA-ARS?s Scientific Manuscript database

Work was conducted in 2008 to determine the stalk rot resistance of RILs from the RHA 280 x RHA 801 population, as well as to begin introgression of previously identified QTL for head rot resistance into elite sunflower germplasm lines. The stalk rot RILs and their testcrosses with cms HA 89 were t...

Influence of tree size, taxonomy, and edaphic conditions on heart rot in mixed-dipterocarp Bornean rainforests: implications for aboveground biomass estimates

NASA Astrophysics Data System (ADS)

Heineman, K. D.; Russo, S. E.; Baillie, I. C.; Mamit, J. D.; Chai, P. P.-K.; Chai, L.; Hindley, E. W.; Lau, B.-T.; Tan, S.; Ashton, P. S.

2015-05-01

Fungal decay of heartwood creates hollows and areas of reduced wood density within the stems of living trees known as heart rot. Although heart rot is acknowledged as a source of error in forest aboveground biomass estimates, there are few datasets available to evaluate the environmental controls over heart rot infection and severity in tropical forests. Using legacy and recent data from drilled, felled, and cored stems in mixed dipterocarp forests in Sarawak, Malaysian Borneo, we quantified the frequency and severity of heart rot, and used generalized linear mixed effect models to characterize the association of heart rot with tree size, wood density, taxonomy, and edaphic conditions. Heart rot was detected in 55% of felled stems > 30 cm DBH, while the detection frequency was lower for stems of the same size evaluated by non-destructive drilling (45%) and coring (23%) methods. Heart rot severity, defined as the percent stem volume lost in infected stems, ranged widely from 0.1-82.8%. Tree taxonomy explained the greatest proportion of variance in heart rot frequency and severity among the fixed and random effects evaluated in our models. Heart rot frequency, but not severity, increased sharply with tree diameter, ranging from 56% infection across all datasets in stems > 50 cm DBH to 11% in trees 10-30 cm DBH. The frequency and severity of heart rot increased significantly in soils with low pH and cation concentrations in topsoil, and heart rot was more common in tree species associated with dystrophic sandy soils than with nutrient-rich clays. When scaled to forest stands, the percent of stem biomass lost to heart rot varied significantly with soil properties, and we estimate that 7% of the forest biomass is in some stage of heart rot decay. This study demonstrates not only that heart rot is a significant source of error in forest carbon estimates, but also that it strongly covaries with soil resources, underscoring the need to account for edaphic variation in estimating carbon storage in tropical forests.

Spatial multi-criteria decision analysis for modelling suitable habitats of Ornithodoros soft ticks in the Western Palearctic region

USDA-ARS?s Scientific Manuscript database

Ticks are economically and medically important due to the injuries inflicted through their bite, and their ability to transmit pathogens to humans, livestock, and wildlife. Whereas hard ticks have been intensively studied, little is known about soft ticks, even though they can transmit several patho...

Non Diphtheritic Corynebacteria: An Emerging Nosocomial Pathogen in Skin and Soft Tissue Infection

PubMed Central

Ravi, GS; Alex, Ann Mary; Mamatha, KR; Sunitha, L; Ramya, K Thangam

2015-01-01

Introduction Non-diphtheritic corynebacteria are normal inhabitants of skin and mucous membrane. When isolated from clinical specimens they are often considered as contaminants. Recent reports suggest their role as emerging nosocomial pathogens. Aim To speciate non-diphtheritic corynebacteria isolated from wound specimens, to correlate their clinical significance and to determine their invitro antimicrobial susceptibilities to 9 antimicrobial agents. Materials and Methods Twenty five non-diphtheritic corynebacteria from skin and soft tissue infections were selected for study. Isolates were identified by battery of tests and minimum inhibitory concentration (MIC) was detected by Clinical & Laboratory Standards Institute (CLSI) described broth microdilution method. MIC was interpreted according CLSI and British Society for Antimicrobial Chemotherapy (BSAC) guidelines. Results C. amycolatum was the predominant species (20%) followed by C. striatum (16%). Penicillin was least effective invitro followed by clindamycin and ciprofloxacin. Excellent activities were shown by vancomycin, linezolid and imipenem. Multidrug resistance was found in all the species. Conclusion Non-diphtheritic corynebacteria are potential nosocomial pathogens among acute/chronic complicated skin and soft tissue infection. Vancomycin or linezolid can be used empirically to treat such infections until the invitro susceptibility results are available. PMID:26816891

Fusarium species as pathogen on orchids.

PubMed

Srivastava, Shikha; Kadooka, Chris; Uchida, Janice Y

2018-03-01

The recent surge in demand for exotic ornamental crops such as orchids has led to a rise in international production, and a sharp increase in the number of plant and plant products moving between countries. Along with the plants, diseases are also being transported and introduced into new areas. Fusarium is one of the major diseases causing pathogens infecting orchids that is spreading through international trade. Studies have identified several species of Fusarium associated with orchids, some are pathogenic and cause symptoms such as leaf and flower spots, leaf or sheath blights, pseudostem or root rots, and wilts. Infection and damage caused by Fusarium reduces the quality of plants and flowers, and can cause severe economic losses. This review documents the current status of the Fusarium-orchid interaction, and illustrates challenges and future perspectives based on the available literature. This review is the first of Fusarium and orchid interactions, and integrates diverse results that both furthers the understanding and knowledge of this disease complex, and will enable the development of effective disease management practices. Copyright © 2017 Elsevier GmbH. All rights reserved.

Developmental and Metabolic Plasticity of White-Skinned Grape Berries in Response to Botrytis cinerea during Noble Rot1[OPEN

PubMed Central

Collins, Thomas S.; Vicente, Ariel R.; Doyle, Carolyn L.; Ye, Zirou; Allen, Greg; Heymann, Hildegarde

2015-01-01

Noble rot results from exceptional infections of ripe grape (Vitis vinifera) berries by Botrytis cinerea. Unlike bunch rot, noble rot promotes favorable changes in grape berries and the accumulation of secondary metabolites that enhance wine grape composition. Noble rot-infected berries of cv Sémillon, a white-skinned variety, were collected over 3 years from a commercial vineyard at the same time that fruit were harvested for botrytized wine production. Using an integrated transcriptomics and metabolomics approach, we demonstrate that noble rot alters the metabolism of cv Sémillon berries by inducing biotic and abiotic stress responses as well as ripening processes. During noble rot, B. cinerea induced the expression of key regulators of ripening-associated pathways, some of which are distinctive to the normal ripening of red-skinned cultivars. Enhancement of phenylpropanoid metabolism, characterized by a restricted flux in white-skinned berries, was a common outcome of noble rot and red-skinned berry ripening. Transcript and metabolite analyses together with enzymatic assays determined that the biosynthesis of anthocyanins is a consistent hallmark of noble rot in cv Sémillon berries. The biosynthesis of terpenes and fatty acid aroma precursors also increased during noble rot. We finally characterized the impact of noble rot in botrytized wines. Altogether, the results of this work demonstrated that noble rot causes a major reprogramming of berry development and metabolism. This desirable interaction between a fruit and a fungus stimulates pathways otherwise inactive in white-skinned berries, leading to a greater accumulation of compounds involved in the unique flavor and aroma of botrytized wines. PMID:26450706

Developmental and Metabolic Plasticity of White-Skinned Grape Berries in Response to Botrytis cinerea during Noble Rot.

PubMed

Blanco-Ulate, Barbara; Amrine, Katherine C H; Collins, Thomas S; Rivero, Rosa M; Vicente, Ariel R; Morales-Cruz, Abraham; Doyle, Carolyn L; Ye, Zirou; Allen, Greg; Heymann, Hildegarde; Ebeler, Susan E; Cantu, Dario

2015-12-01

Noble rot results from exceptional infections of ripe grape (Vitis vinifera) berries by Botrytis cinerea. Unlike bunch rot, noble rot promotes favorable changes in grape berries and the accumulation of secondary metabolites that enhance wine grape composition. Noble rot-infected berries of cv Sémillon, a white-skinned variety, were collected over 3 years from a commercial vineyard at the same time that fruit were harvested for botrytized wine production. Using an integrated transcriptomics and metabolomics approach, we demonstrate that noble rot alters the metabolism of cv Sémillon berries by inducing biotic and abiotic stress responses as well as ripening processes. During noble rot, B. cinerea induced the expression of key regulators of ripening-associated pathways, some of which are distinctive to the normal ripening of red-skinned cultivars. Enhancement of phenylpropanoid metabolism, characterized by a restricted flux in white-skinned berries, was a common outcome of noble rot and red-skinned berry ripening. Transcript and metabolite analyses together with enzymatic assays determined that the biosynthesis of anthocyanins is a consistent hallmark of noble rot in cv Sémillon berries. The biosynthesis of terpenes and fatty acid aroma precursors also increased during noble rot. We finally characterized the impact of noble rot in botrytized wines. Altogether, the results of this work demonstrated that noble rot causes a major reprogramming of berry development and metabolism. This desirable interaction between a fruit and a fungus stimulates pathways otherwise inactive in white-skinned berries, leading to a greater accumulation of compounds involved in the unique flavor and aroma of botrytized wines. © 2015 American Society of Plant Biologists. All Rights Reserved.

Cell wall integrity modulates RHO1 activity via the exchange factor ROM2.

PubMed Central

Bickle, M; Delley, P A; Schmidt, A; Hall, M N

1998-01-01

The essential phosphatidylinositol kinase homologue TOR2 of Saccharomyces cerevisiae controls the actin cytoskeleton by activating a GTPase switch consisting of RHO1 (GTPase), ROM2 (GEF) and SAC7 (GAP). We have identified two mutations, rot1-1 and rot2-1, that suppress the loss of TOR2 and are synthetic-lethal. The wild-type ROT1 and ROT2 genes and a multicopy suppressor, BIG1, were isolated by their ability to rescue the rot1-1 rot2-1 double mutant. ROT2 encodes glucosidase II, and ROT1 and BIG1 encode novel proteins. We present evidence that cell wall defects activate RHO1. First, rot1, rot2, big1, cwh41, gas1 and fks1 mutations all confer cell wall defects and suppress tor2(ts). Second, destabilizing the cell wall by supplementing the growth medium with 0.005% SDS also suppresses a tor2(ts) mutation. Third, disturbing the cell wall with SDS or a rot1, rot2, big1, cwh41, gas1 or fks1 mutation increases GDP/GTP exchange activity toward RHO1. These results suggest that cell wall defects suppress a tor2 mutation by activating RHO1 independently of TOR2, thereby inducing TOR2-independent polarization of the actin cytoskeleton and cell wall synthesis. Activation of RHO1, a subunit of the cell wall synthesis enzyme glucan synthase, by a cell wall alteration would ensure that cell wall synthesis occurs only when and where needed. The mechanism of RHO1 activation by a cell wall alteration is via the exchange factor ROM2 and could be analogous to signalling by integrin receptors in mammalian cells. PMID:9545237

Energy balance associated with the degradation of lignocellulosic material by white-rot and brown-rot fungi.

NASA Astrophysics Data System (ADS)

Derrien, Delphine; Bédu, Hélène; Buée, Marc; Kohler, Annegret; Goodell, Barry; Gelhaye, Eric

2017-04-01

Forest soils cover about 30% of terrestrial area and comprise between 50 and 80% of the global stock of soil organic carbon (SOC). The major precursor for this forest SOC is lignocellulosic material, which is made of polysaccharides and lignin. Lignin has traditionally been considered as a recalcitrant polymer that hinders access to the much more labile structural polysaccharides. This view appears to be partly incorrect from a microbiology perspective yet, as substrate alteration depends on the metabolic potential of decomposers. In forest ecosystems the wood-rotting Basidiomycota fungi have developed two different strategies to attack the structure of lignin and gain access to structural polysaccharides. White-rot fungi degrade all components of plant cell walls, including lignin, using enzymatic systems. Brown-rot fungi do not remove lignin. They generate oxygen-derived free radicals, such as the hydroxyl radical produced by the Fenton reaction, that disrupt the lignin polymer and depolymerize polysaccharides which then diffuse out to where the enzymes are located The objective of this study was to develop a model to investigate whether the lignin relative persistence could be related to the energetic advantage of brown-rot degradative pathway in comparison to white-rot degradative pathway. The model simulates the changes in substrate composition over time, and determines the energy gained from the conversion of the lost substrate into CO2. The energy cost for the production of enzymes involved in substrate alteration is assessed using information derived from genome and secretome analysis. For brown-rot fungus specifically, the energy cost related to the production of OH radicals is also included. The model was run, using data from the literature on populous wood degradation by Trametes versicolor, a white-rot fungus, and Gloeophyllum trabeum, a brown-rot fungus. It demonstrates that the brown-rot fungus (Gloeophyllum trabeum) was more efficient than the white-rot fungus (Trametes versicolor). The energy advantage could explain the emergence of the brown-rot degradative pathway from a white-rot degradative pathway and subsequently, the relative persistence of lignin in soil.

The non-gibberellic acid-responsive semi-dwarfing gene uzu affects Fusarium crown rot resistance in barley.

PubMed

Chen, Guangdeng; Yan, Wei; Liu, Yaxi; Wei, Yuming; Zhou, Meixue; Zheng, You-Liang; Manners, John M; Liu, Chunji

2014-01-13

Studies in Arabidopsis show that DELLA genes may differentially affect responses to biotrophic and necrophic pathogens. A recent report based on the study of DELLA-producing reduced height (Rht) genes in wheat and barley also hypothesized that DELLA genes likely increased susceptibility to necrotrophs but increased resistance to biotrophs. Effects of uzu, a non-GA (gibberellic acid)-responsive semi-dwarfing gene, on Fusarium crown rot (FCR) resistance in barley were investigated. Fifteen pairs of near isogenic lines for this gene were generated and assessed under two different temperature regimes. Similar to its impacts on plant height, the semi-dwarfing gene uzu also showed larger effects on FCR severity in the high temperature regime when compared with that in the low temperature regime. Results from this study add to the growing evidence showing that the effects of plant height on Fusarium resistances are unlikely related to DELLA genes but due to direct or indirect effects of height difference per se. The interaction between these two characteristics highlights the importance of understanding relationships between resistance and other traits of agronomic importance as the value of a resistance gene could be compromised if it dramatically affects plant development and morphology.

Brown Rot Strikes Prunus Fruit: An Ancient Fight Almost Always Lost.

PubMed

Oliveira Lino, Leandro; Pacheco, Igor; Mercier, Vincent; Faoro, Franco; Bassi, Daniele; Bornard, Isabelle; Quilot-Turion, Bénédicte

2016-05-25

Brown rot (BR) caused by Monilinia spp., has been an economic problem for the stone fruit market due to dramatic losses, mainly during the postharvest period. There is much literature about basic aspects of Monilinia spp. infection, which indicates that environment significantly influences its occurrence in the orchard. However, progress is needed to sustainably limit this disease: the pathogen is able to develop resistance to pesticides, and most of BR resistance research programs in plant models perish. Solving this problem becomes important due to the need to decrease chemical treatments and reduce residues on fruit. Thus, research has recently increased, exploring a wide range of disease control strategies (e.g., genetic, chemical, physical). Summarizing this information is difficult, as studies evaluate different Monilinia and Prunus model species, with diverse strategies and protocols. Thus, the purpose of this review is to present the diversity and distribution of agents causing BR, focusing on the biochemical mechanisms of Monilinia spp. infection both of the fungi and of the fruit, and report on the resistance sources in Prunus germplasm. This review comprehensively compiles the information currently available to better understand mechanisms related to BR resistance.

Impact of motility and chemotaxis features of the rhizobacterium Pseudomonas chlororaphis PCL1606 on its biocontrol of avocado white root rot.

PubMed

Polonio, Álvaro; Vida, Carmen; de Vicente, Antonio; Cazorla, Francisco M

2017-06-01

The biocontrol rhizobacterium Pseudomonas chlororaphis PCL1606 has the ability to protect avocado plants against white root rot produced by the phytopathogenic fungus Rosellinia necatrix. Moreover, PCL1606 displayed direct interactions with avocado roots and the pathogenic fungus. Thus, nonmotile (flgK mutant) and non-chemotactic (cheA mutant) derivatives of PCL1606 were constructed to emphasize the importance of motility and chemotaxis in the biological behaviour of PCL1606 during the biocontrol interaction. Plate chemotaxis assay showed that PCL1606 was attracted to the single compounds tested, such as glucose, glutamate, succinate, aspartate and malate, but no chemotaxis was observed to avocado or R. necatrix exudates. Using the more sensitive capillary assay, it was reported that smaller concentrations (1 mM) of single compounds elicited high chemotactic responses, and strong attraction was confirmed to avocado and R. necatrix exudates. Finally, biocontrol experiments revealed that the cheA and fglK derivative mutants reduced root protection against R. necatrix, suggesting an important role for these biological traits in biocontrol by P. chlororaphis PCL1606. [Int Microbiol 20(2):94-104 (2017)]. Copyright© by the Spanish Society for Microbiology and Institute for Catalan Studies.

Development of Molecular Methods to Detect Macrophomina phaseolina from Strawberry Plants and Soil.

PubMed

Burkhardt, Alyssa; Ramon, Marina L; Smith, Brett; Koike, Steven T; Martin, Frank N

2018-06-05

Macrophomina phaseolina is a broad-host range fungus that shows some degree of host preference on strawberry, and causes symptoms including crown rot and root rot. Recently, this pathogen has impacted strawberry production as fumigation practices have changed, leaving many growers in California and around the world in need of accurate, rapid diagnostic tools for M. phaseolina in soil and infected plants. This study uses next-generation sequencing and comparative genomics to identify a locus that is unique to isolates within a main genotype shared by a majority of isolates that infect strawberry. This locus was used to develop a quantitative single-tube nested TaqMan qPCR assay which is able to quantify as little as 2-3 microsclerotia/g of soil with 100% genotype specificity. An isothermal assay using recombinase polymerase amplification (RPA) was developed from the same locus and has been validated on over 200 infected strawberry plants with a diagnostic sensitivity of 93% and a diagnostic specificity of 99%, respectively. Together, this work demonstrates the value of using new approaches to identify loci for detection and provides valuable diagnostic tools that can be used to monitor soil and strawberry plant samples for M. phaseolina.

Biological Control of Phytophthora palmivora Causing Root Rot of Pomelo Using Chaetomium spp.

PubMed Central

Wattanachai, Pongnak; Kasem, Soytong; Poaim, Supatta

2015-01-01

Phytophthora diseases have become a major impediment in the citrus production in Thailand. In this study, an isolate of Phytophthora denominated as PHY02 was proven to be causal pathogen of root rot of Pomelo (Citrus maxima) in Thailand. The isolate PHY02 was morphologically characterized and identified as Phytophthora palmivora based on molecular analysis of an internal transcribed spacer rDNA sequence. This work also presents in vitro evaluations of the capacities of Chaetomium spp. to control the P. palmivora PHY02. As antagonists, Chaetomium globosum CG05, Chaetomium cupreum CC3003, Chaetomium lucknowense CL01 inhibited 50~61% mycelial growth, degraded mycelia and reduced 92~99% sporangial production of P. palmivora PHY02 in bi-culture test after 30 days. Fungal metabolites from Chaetomium spp. were tested against PHY02. Results showed that, methanol extract of C. globosum CG05 expressed strongest inhibitory effects on mycelial growth and sporangium formation of P. palmivora PHY02 with effective dose ED50 values of 26.5 µg/mL and 2.3 µg/mL, respectively. It is interesting that C. lucknowense is reported for the first time as an effective antagonist against a species of Phytophthora. PMID:25892917

Detection and characterization of broad-spectrum antipathogen activity of novel rhizobacterial isolates and suppression of Fusarium crown and root rot disease of tomato.

PubMed

Zhang, L; Khabbaz, S E; Wang, A; Li, H; Abbasi, P A

2015-03-01

To detect and characterize broad-spectrum antipathogen activity of indigenous bacterial isolates obtained from potato soil and soya bean leaves for their potential to be developed as biofungicides to control soilborne diseases such as Fusarium crown and root rot of tomato (FCRR) caused by Fusarium oxysporum f. sp. radicis-lycopersici (Forl). Thirteen bacterial isolates (Bacillus amyloliquefaciens (four isolates), Paenibacillus polymyxa (three isolates), Pseudomonas chlororaphis (two isolates), Pseudomonas fluorescens (two isolates), Bacillus subtilis (one isolate) and Pseudomonas sp. (one isolate)) or their volatiles showed antagonistic activity against most of the 10 plant pathogens in plate assays. Cell-free culture filtrates (CF) of five isolates or 1-butanol extracts of CFs also inhibited the growth of most pathogen mycelia in plate assays. PCR analysis confirmed the presence of most antibiotic biosynthetic genes such as phlD, phzFA, prnD and pltC in most Pseudomonas isolates and bmyB, bacA, ituD, srfAA and fenD in most Bacillus isolates. These bacterial isolates varied in the production of hydrogen cyanide (HCN), siderophores, β-1,3-glucanases, chitinases, proteases, indole-3-acetic acid, salicylic acid, and for nitrogen fixation and phosphate solubilization. Gas chromatography-mass spectrometry analysis identified 10 volatile compounds from 10 isolates and 18 compounds from 1-butanol extracts of CFs of five isolates. Application of irradiated peat formulation of six isolates to tomato roots prior to transplanting in a Forl-infested potting mix and field soil provided protection of tomato plants from FCRR disease and enhanced plant growth under greenhouse conditions. Five of the 13 indigenous bacterial isolates were antagonistic to eight plant pathogens, both in vitro and in vivo. Antagonistic and plant-growth promotion activities of these isolates might be related to the production of several types of antibiotics, lytic enzymes, phytohormones, secondary metabolites, siderophores and volatile compounds; however, any specific role of each needs to be determined. Indigenous antagonistic bacterial isolates have the potential to be developed as biofungicides for minimizing early crop losses due to soilborne diseases caused by Fusarium and other soilborne pathogens. © 2014 Her Majesty the Queen in Right of Canada © 2014 The Society for Applied Microbiology. Reproduced with the permission of the Minister of Agriculture and Agri-Food Canada.

Skin and Soft Tissue Infections (Patera Foot) in Immigrants, Spain

PubMed Central

Ternavasio-de la Vega, Hugo-Guillermo; Ángel-Moreno, Alfonso; Hernández-Cabrera, Michele; Pisos-Álamo, Elena; Bolaños-Rivero, Margarita; Carranza-Rodriguez, Cristina; Calderín-Ortega, Antonio; Pérez-Arellano, José-Luis

2009-01-01

An unusual skin and soft tissue infection of the lower limbs has been observed in immigrants from sub-Saharan Africa who cross the Atlantic Ocean crowded on small fishing boats (pateras). Response to conventional treatment is usually poor. Extreme extrinsic factors (including new pathogens) may contribute to the etiology of the infection and its pathogenesis. PMID:19331742

Adult plant leaf rust resistance derived from the soft red winter wheat cultivar Caldwell maps to chromosome 3BS

USDA-ARS?s Scientific Manuscript database

'Caldwell' is a U.S. soft red winter wheat that has partial, adult plant resistance to the leaf rust pathogen Puccinia triticina. A line of 'Thatcher*2/Caldwell' with adult plant resistance derived from Caldwell was crossed with 'Thatcher' to develop a population of recombinant inbred lines (RILs). ...

Outcomes of single organism peritonitis in peritoneal dialysis: gram negatives versus gram positives in the Network 9 Peritonitis Study.

PubMed

Bunke, C M; Brier, M E; Golper, T A

1997-08-01

The use of the "peritonitis rate" in the management of patients undergoing peritoneal dialysis is assuming importance in comparing the prowess of facilities, care givers and new innovations. For this to be a meaningful outcome measure, the type of infection (causative pathogen) must have less clinical significance than the number of infections during a time interval. The natural history of Staphylococcus aureus, pseudomonas, and fungal peritonitis would not support that the outcome of an episode of peritonitis is independent of the causative pathogen. Could this concern be extended to other more frequently occurring pathogens? To address this, the Network 9 Peritonitis Study identified 530 episodes of single organism peritonitis caused by a gram positive organism and 136 episodes caused by a single non-pseudomonal gram negative (NPGN) pathogen. Coincidental soft tissue infections (exit site or tunnel) occurred equally in both groups. Outcomes of peritonitis were analyzed by organism classification and by presence or absence of a soft tissue infection. NPGN peritonitis was associated with significantly more frequent catheter loss, hospitalization, and technique failure and was less likely to resolve regardless of the presence or absence of a soft tissue infection. Hospitalization and death tended to occur more frequently with enterococcal peritonitis than with other gram positive peritonitis. The outcomes in the NPGN peritonitis group were significantly worse (resolution, catheter loss, hospitalization, technique failure) compared to coagulase negative staphylococcal or S. aureus peritonitis, regardless of the presence or absence of a coincidental soft tissue infection. Furthermore, for the first time, the poor outcomes of gram negative peritonitis are shown to be independent of pseudomonas or polymicrobial involvement or soft tissue infections. The gram negative organism appears to be the important factor. In addition, the outcome of peritonitis caused by S. aureus is worse than that of other staphylococci. Thus, it is clear that all peritonitis episodes cannot be considered equivalent in terms of outcome. The concept of peritonitis rate is only meaningful when specific organisms are considered.

Ethanol, vinegar and Origanum vulgare oil vapour suppress the development of anthracnose rot in tomato fruit.

PubMed

Tzortzakis, Nikos G

2010-08-15

Anthracnose rot (Colletotrichum coccodes) development in vitro or in tomato (Lycopersicon esculentum L.) fruit was evaluated after treatment with absolute ethyl alcohol (AEA), vinegar (VIN), chlorine (CHL) or origanum oil (ORI) and storage at 12 degrees C and 95% relative humidity during or following exposure to the volatiles. Fruit treated with vapours reduced fungal spore germination/production, but in the case of AEA- and VIN-treated fruits, fungal mycelium development was accelerated. Fruit lesion development was suppressed after fruit exposure to pure (100% v/v) AEA or ORI vapours which were accompanied by increased fruit cracking. Exposure to pure VIN-, CHL- and ORI vapours reduced (up to 92%) spore germination in vitro, but no differences were observed in the AEA treatment. The benefits associated with volatiles-enrichment were maintained in fruit pre-exposed to vapours, resulting in suppression in spore germination and spore production. However, studies performed on fungi grown on Potato Dextrose Agar revealed fewer direct effects of volatiles on fungal colony development and spore germination per se, implying that suppression of pathogen development was due in a large part to the impact of volatiles on fruit-pathogen interactions and/or 'memory' effects on fruit tissue. Work is currently focussing on the mechanisms underlying the impacts of volatiles on fruit quality related attributes. The results of this study indicate that volatiles may be considered as an alternative to the traditional postharvest sanitizing techniques. Each commodity needs to be individually assessed, and the volatile concentration and sanitising technique optimised, before the volatile treatment is used commercially. Copyright 2010 Elsevier B.V. All rights reserved.

In vitro growth and cell wall degrading enzyme production by Argentinean isolates of Macrophomina phaseolina, the causative agent of charcoal rot in corn.

PubMed

Ramos, Araceli M; Gally, Marcela; Szapiro, Gala; Itzcovich, Tatiana; Carabajal, Maira; Levin, Laura

Macrophomina phaseolina is a polyphagous phytopathogen, causing stalk rot on many commercially important species. Damages caused by this pathogen in soybean and maize crops in Argentina during drought and hot weather have increased due its ability to survive as sclerotia in soil and crop debris under non-till practices. In this work, we explored the in vitro production of plant cell wall-degrading enzymes [pectinases (polygalacturonase and polymethylgalacturonase); cellulases (endoglucanase); hemicellulases (endoxylanase) and the ligninolytic enzyme laccase] by several Argentinean isolates of M. phaseolina, and assessed the pathogenicity of these isolates as a preliminary step to establish the role of these enzymes in M. phaseolina-maize interaction. The isolates were grown in liquid synthetic medium supplemented with glucose, pectin, carboxymethylcellulose or xylan as carbon sources and/or enzyme inducers and glutamic acid as nitrogen source. Pectinases were the first cell wall-degrading enzymes detected and the activities obtained (polygalacturonase activity was between 0.4 and 1.3U/ml and polymethylgalacturonase between 0.15 and 1.3U/ml) were higher than those of cellulases and xylanases, which appeared later and in a lesser magnitude. This sequence would promote initial tissue maceration followed by cell wall degradation. Laccase was detected in all the isolates evaluated (activity was between 36U/l and 63U/l). The aggressiveness of the isolates was tested in maize, sunflower and watermelon seeds, being high on all the plants assayed. This study reports for the first time the potential of different isolates of M. phaseolina to produce plant cell wall-degrading enzymes in submerged fermentation. Copyright © 2016 Asociación Argentina de Microbiología. Publicado por Elsevier España, S.L.U. All rights reserved.

Molecular Basis of Resistance to Fusarium Ear Rot in Maize.

PubMed

Lanubile, Alessandra; Maschietto, Valentina; Borrelli, Virginia M; Stagnati, Lorenzo; Logrieco, Antonio F; Marocco, Adriano

2017-01-01

The impact of climate change has been identified as an emerging issue for food security and safety, and the increased incidence of mycotoxin contamination in maize over the last two decades is considered a potential emerging hazard. Disease control by chemical and agronomic approaches is often ineffective and increases the cost of production; for this reason the exploitation of genetic resistance is the most sustainable method for reducing contamination. The review focuses on the significant advances that have been made in the development of transcriptomic, genetic and genomic information for maize, Fusarium verticillioides molds, and their interactions, over recent years. Findings from transcriptomic studies have been used to outline a specific model for the intracellular signaling cascade occurring in maize cells against F. verticillioides infection. Several recognition receptors, such as receptor-like kinases and R genes, are involved in pathogen perception, and trigger down-stream signaling networks mediated by mitogen-associated protein kinases. These signals could be orchestrated primarily by hormones, including salicylic acid, auxin, abscisic acid, ethylene, and jasmonic acid, in association with calcium signaling, targeting multiple transcription factors that in turn promote the down-stream activation of defensive response genes, such as those related to detoxification processes, phenylpropanoid, and oxylipin metabolic pathways. At the genetic and genomic levels, several quantitative trait loci (QTL) and single-nucleotide polymorphism markers for resistance to Fusarium ear rot deriving from QTL mapping and genome-wide association studies are described, indicating the complexity of this polygenic trait. All these findings will contribute to identifying candidate genes for resistance and to applying genomic technologies for selecting resistant maize genotypes and speeding up a strategy of breeding to contrast disease, through plants resistant to mycotoxin-producing pathogens.

Molecular Basis of Resistance to Fusarium Ear Rot in Maize

PubMed Central

Lanubile, Alessandra; Maschietto, Valentina; Borrelli, Virginia M.; Stagnati, Lorenzo; Logrieco, Antonio F.; Marocco, Adriano

2017-01-01

The impact of climate change has been identified as an emerging issue for food security and safety, and the increased incidence of mycotoxin contamination in maize over the last two decades is considered a potential emerging hazard. Disease control by chemical and agronomic approaches is often ineffective and increases the cost of production; for this reason the exploitation of genetic resistance is the most sustainable method for reducing contamination. The review focuses on the significant advances that have been made in the development of transcriptomic, genetic and genomic information for maize, Fusarium verticillioides molds, and their interactions, over recent years. Findings from transcriptomic studies have been used to outline a specific model for the intracellular signaling cascade occurring in maize cells against F. verticillioides infection. Several recognition receptors, such as receptor-like kinases and R genes, are involved in pathogen perception, and trigger down-stream signaling networks mediated by mitogen-associated protein kinases. These signals could be orchestrated primarily by hormones, including salicylic acid, auxin, abscisic acid, ethylene, and jasmonic acid, in association with calcium signaling, targeting multiple transcription factors that in turn promote the down-stream activation of defensive response genes, such as those related to detoxification processes, phenylpropanoid, and oxylipin metabolic pathways. At the genetic and genomic levels, several quantitative trait loci (QTL) and single-nucleotide polymorphism markers for resistance to Fusarium ear rot deriving from QTL mapping and genome-wide association studies are described, indicating the complexity of this polygenic trait. All these findings will contribute to identifying candidate genes for resistance and to applying genomic technologies for selecting resistant maize genotypes and speeding up a strategy of breeding to contrast disease, through plants resistant to mycotoxin-producing pathogens. PMID:29075283

Identification of proteins in susceptible and resistant Brassica oleracea responsive to Xanthomonas campestris pv. campestris infection.

PubMed

Villeth, Gabriela R C; Carmo, Lílian S T; Silva, Luciano Paulino; Santos, Mateus Figueiredo; de Oliveira Neto, Osmundo Brilhante; Grossi-de-Sá, Maria Fátima; Ribeiro, Igor Sousa; Dessaune, Suelen Nogueira; Fragoso, Rodrigo Rocha; Franco, Octávio L; Mehta, Angela

2016-06-30

Cruciferous plants are important edible vegetables widely consumed around the world, including cabbage, cauli-flower and broccoli. The main disease that affects crucifer plants is black rot, caused by Xanthomonas campestris pv. campestris (Xcc). In order to better understand this specific plant-pathogen interaction, proteins responsive to Xcc infection in resistant (União) and susceptible (Kenzan) Brassica oleracea cultivars were investigated by 2-DE followed by mass spectrometry. A total of 47 variable spots were identified and revealed that in the susceptible interaction there is a clear reduction in the abundance of proteins involved in energetic metabolism and defense. It was interesting to observe that in the resistant interaction, these proteins showed an opposite behavior. Based on our results, we conclude that resistance is correlated with the ability of the plant to keep sufficient photosynthesis metabolism activity to provide energy supplies necessary for an active defense. As a follow-up study, qRT-PCR analysis of selected genes was performed and revealed that most genes showed an up-regulation trend from 5 to 15days after inoculation (DAI), showing highest transcript levels at 15DAI. These results revealed the gradual accumulation of transcripts providing a more detailed view of the changes occurring during different stages of the plant-pathogen interaction. In this study we have compared cultivars of Brassica oleracea (cabbage), susceptible and resistant to black rot, by using the classical 2-DE approach. We have found that resistance is correlated with the ability of the plant to keep sufficient photosynthesis metabolism activity to provide energy supplies necessary for an active defense. Copyright © 2016 Elsevier B.V. All rights reserved.

Transcriptome and Allele Specificity Associated with a 3BL Locus for Fusarium Crown Rot Resistance in Bread Wheat

PubMed Central

Ma, Jian; Stiller, Jiri; Zhao, Qiang; Feng, Qi; Cavanagh, Colin; Wang, Penghao; Gardiner, Donald; Choulet, Frédéric; Feuillet, Catherine; Zheng, You-Liang; Wei, Yuming; Yan, Guijun; Han, Bin; Manners, John M.; Liu, Chunji

2014-01-01

Fusarium pathogens cause two major diseases in cereals, Fusarium crown rot (FCR) and head blight (FHB). A large-effect locus conferring resistance to FCR disease was previously located to chromosome arm 3BL (designated as Qcrs-3B) and several independent sets of near isogenic lines (NILs) have been developed for this locus. In this study, five sets of the NILs were used to examine transcriptional changes associated with the Qcrs-3B locus and to identify genes linked to the resistance locus as a step towards the isolation of the causative gene(s). Of the differentially expressed genes (DEGs) detected between the NILs, 12.7% was located on the single chromosome 3B. Of the expressed genes containing SNP (SNP-EGs) detected, 23.5% was mapped to this chromosome. Several of the DEGs and SNP-EGs are known to be involved in host-pathogen interactions, and a large number of the DEGs were among those detected for FHB in previous studies. Of the DEGs detected, 22 were mapped in the Qcrs-3B interval and they included eight which were detected in the resistant isolines only. The enrichment of DEG, and not necessarily those containing SNPs between the resistant and susceptible isolines, around the Qcrs-3B locus is suggestive of local regulation of this region by the resistance allele. Functions for 13 of these DEGs are known. Of the SNP-EGs, 28 were mapped in the Qcrs-3B interval and biological functions for 16 of them are known. These results provide insights into responses regulated by the 3BL locus and identify a tractable number of target genes for fine mapping and functional testing to identify the causative gene(s) at this QTL. PMID:25405461

An in vitro study of the antifungal activity of Trichoderma virens 7b and a profile of its non-polar antifungal components released against Ganoderma boninense.

PubMed

Angel, Lee Pei Lee; Yusof, Mohd Termizi; Ismail, Intan Safinar; Ping, Bonnie Tay Yen; Mohamed Azni, Intan Nur Ainni; Kamarudin, Norman Hj; Sundram, Shamala

2016-11-01

Ganoderma boninense is the causal agent of a devastating disease affecting oil palm in Southeast Asian countries. Basal stem rot (BSR) disease slowly rots the base of palms, which radically reduces productive lifespan of this lucrative crop. Previous reports have indicated the successful use of Trichoderma as biological control agent (BCA) against G. boninense and isolate T. virens 7b was selected based on its initial screening. This study attempts to decipher the mechanisms responsible for the inhibition of G. boninense by identifying and characterizing the chemical compounds as well as the physical mechanisms by T. virens 7b. Hexane extract of the isolate gave 62.60% ± 6.41 inhibition against G. boninense and observation under scanning electron microscope (SEM) detected severe mycelial deformation of the pathogen at the region of inhibition. Similar mycelia deformation of G. boninense was observed with a fungicide treatment, Benlate ® indicating comparable fungicidal effect by T. virens 7b. Fraction 4 and 5 of hexane active fractions through preparative thin layer chromatography (P-TLC) was identified giving the best inhibition of the pathogen. These fractions comprised of ketones, alcohols, aldehydes, lactones, sesquiterpenes, monoterpenes, sulphides, and free fatty acids profiled through gas chromatography mass spectrometry detector (GC/MSD). A novel antifungal compound discovery of phenylethyl alcohol (PEA) by T. virens 7b is reported through this study. T. virens 7b also proved to be an active siderophore producer through chrome azurol S (CAS) agar assay. The study demonstrated the possible mechanisms involved and responsible in the successful inhibition of G. boninense.

Resistance to Fusarium verticillioides and fumonisin accumulation in maize inbred lines involves an earlier and enhanced expression of lipoxygenase (LOX) genes.

PubMed

Maschietto, Valentina; Marocco, Adriano; Malachova, Alexandra; Lanubile, Alessandra

2015-09-01

Fusarium verticillioides causes ear rot in maize and contaminates the kernels with the fumonisin mycotoxins. It is known that plant lipoxygenase (LOX)-derived oxylipins regulate defence against pathogens and that the host-pathogen lipid cross-talk influences the pathogenesis. The expression profiles of fifteen genes of the LOX pathway were studied in kernels of resistant and susceptible maize lines, grown in field condition, at 3, 7 and 14 days post inoculation (dpi) with F. verticillioides. Plant defence responses were correlated with the pathogen growth, the expression profiles of fungal FUM genes for fumonisin biosynthesis and fumonisin content in the kernels. The resistant genotype limited fungal growth and fumonisin accumulation between 7 and 14 dpi. Pathogen growth became exponential in the susceptible line after 7 dpi, in correspondence with massive transcription of FUM genes and fumonisins augmented exponentially at 14 dpi. LOX pathway genes resulted strongly induced after pathogen inoculation in the resistant line at 3 and 7 dpi, whilst in the susceptible line the induction was reduced or delayed at 14 dpi. In addition, all genes resulted overexpressed before infection in kernels of the resistant genotype already at 3 dpi. The results suggest that resistance in maize may depend on an earlier activation of LOX genes and genes for jasmonic acid biosynthesis. Copyright © 2015 Elsevier GmbH. All rights reserved.

Survival of two bacterial fish pathogens (Aeromonas salmonicida and the Enteric Redmouth Bacterium) in ozonated, chlorinated, and untreated waters

USGS Publications Warehouse

Wedemeyer, Gary A.; Nelson, Nancy C.

1977-01-01

Ozone and chlorine inactivation curves were determined in three water types at 20 °C for the destruction of the fish pathogens Aeromonas salmonicida, the etiologic agent of furunculosis, and the enteric redmouth bacterium (ERM). In phosphate-buffered distilled water, 0.01 mg/ℓ ozone inactivated 103 cells/ml of ERM and A. salmonicida in 1/2 and 10 min, respectively. Chlorine at this concentration had little effect on either pathogen and a residual of at least 0.05 mg/ℓ was needed to achieve a complete kill within a 10-min contact time. In soft lake water (30 mg/ℓ as CaCO3) a chlorine residual of 0.1 mg/ℓ rapidly  inactivated A. salmonicida and ERM but in hard water (120 mg/ℓ) A. salmonicida was more resistant and 0.2 mg/ℓ chlorine was required. Ozonation of the two lake waters at 90 mg O3∙h−1∙ℓ−1 (equivalent to a 0.01 mg/ℓ residual in ozone demand-free water) was required to destroy both pathogens within 10 min.In untreated soft lake water 103 cells/ml of A. salmonicida survived only 2 days, while the ERM bacterium (103 cells/ml) survived even after 20 day s in soft and hard untreated lake waters.

7 CFR 29.6039 - Stem rot.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 7 Agriculture 2 2010-01-01 2010-01-01 false Stem rot. 29.6039 Section 29.6039 Agriculture... INSPECTION Standards Definitions § 29.6039 Stem rot. The deterioration of an uncured or frozen stem resulting from bacterial action. Although stem rot results from bacterial action, it is inactive in cured tobacco...

7 CFR 29.6039 - Stem rot.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 7 Agriculture 2 2014-01-01 2014-01-01 false Stem rot. 29.6039 Section 29.6039 Agriculture... INSPECTION Standards Definitions § 29.6039 Stem rot. The deterioration of an uncured or frozen stem resulting from bacterial action. Although stem rot results from bacterial action, it is inactive in cured tobacco...