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  1. Externally imposed electric field enhances plant root tip regeneration.

    PubMed

    Kral, Nicolas; Hanna Ougolnikova, Alexandra; Sena, Giovanni

    2016-06-01

    In plants, shoot and root regeneration can be induced in the distinctive conditions of tissue culture (in vitro) but is also observed in intact individuals (in planta) recovering from tissue damage. Roots, for example, can regenerate their fully excised meristems in planta, even in mutants with impaired apical stem cell niches. Unfortunately, to date a comprehensive understanding of regeneration in plants is still missing. Here, we provide evidence that an imposed electric field can perturb apical root regeneration in Arabidopsis. Crucially, we explored both spatial and temporal competences of the stump to respond to electrical stimulation, by varying respectively the position of the cut and the time interval between excision and stimulation. Our data indicate that a brief pulse of an electric field parallel to the root is sufficient to increase by up to two-fold the probability of its regeneration, and to perturb the local distribution of the hormone auxin, as well as cell division regulation. Remarkably, the orientation of the root towards the anode or the cathode is shown to play a role. PMID:27606066

  2. Externally imposed electric field enhances plant root tip regeneration

    PubMed Central

    Kral, Nicolas; Hanna Ougolnikova, Alexandra

    2016-01-01

    Abstract In plants, shoot and root regeneration can be induced in the distinctive conditions of tissue culture (in vitro) but is also observed in intact individuals (in planta) recovering from tissue damage. Roots, for example, can regenerate their fully excised meristems in planta, even in mutants with impaired apical stem cell niches. Unfortunately, to date a comprehensive understanding of regeneration in plants is still missing. Here, we provide evidence that an imposed electric field can perturb apical root regeneration in Arabidopsis. Crucially, we explored both spatial and temporal competences of the stump to respond to electrical stimulation, by varying respectively the position of the cut and the time interval between excision and stimulation. Our data indicate that a brief pulse of an electric field parallel to the root is sufficient to increase by up to two‐fold the probability of its regeneration, and to perturb the local distribution of the hormone auxin, as well as cell division regulation. Remarkably, the orientation of the root towards the anode or the cathode is shown to play a role. PMID:27606066

  3. In situ stimulation vs. bioaugmentation: Can microbial inoculation of plant roots enhance biodegradation of organic compounds?

    SciTech Connect

    Kingsley, M.T.; Metting, F.B. Jr.; Fredrickson, J.K.; Seidler, R.J.

    1993-06-01

    The use of plant roots and their associated rhizosphere bacteria for biocontainment and biorestoration offers several advantages for treating soil-dispersed contaminants and for application to large land areas. Plant roots function as effective delivery systems, since root growth transports bacteria vertically and laterally along the root in the soil column (see [ 1,2]). Movement of microbes along roots and downward in the soil column can be enhanced via irrigation [1-4]. For example, Ciafardini et al. [3] increased the nodulation and the final yield of soybeans during pod filling by including Bradyrhizobium japonicum in the irrigation water. Using rhizosphere microorganisms is advantageous for biodegradation of compounds that are degraded mainly by cometabolic processes, e.g., trichloroethylene (TCE). The energy source for bacterial growth and metabolism is supplied by the plant in the form of root exudates and other sloughed organic material. Plants are inexpensive, and by careful choice of species that possess either tap or fibrous root growth patterns, they can be used to influence mass transport of soil contaminants to the root surface via the transpiration stream [5]. Cropping of plants to remove heavy metals from contaminated soils has been proposed as a viable, low-cost, low-input treatment option [6]. The interest in use of plants as a remediation strategy has even reached the popular press [7], where the use of ragweed for the reclamation of sites contaminated with tetraethyl lead and other heavy metals was discussed.

  4. Water Deficit Enhances C Export to the Roots in Arabidopsis thaliana Plants with Contribution of Sucrose Transporters in Both Shoot and Roots1[OPEN

    PubMed Central

    Durand, Mickaël; Porcheron, Benoît; Maurousset, Laurence; Lemoine, Rémi; Pourtau, Nathalie

    2016-01-01

    Root high plasticity is an adaptation to its changing environment. Water deficit impairs growth, leading to sugar accumulation in leaves, part of which could be available to roots via sucrose (Suc) phloem transport. Phloem loading is widely described in Arabidopsis (Arabidopsis thaliana), while unloading in roots is less understood. To gain information on leaf-to-root transport, a soil-based culture system was developed to monitor root system architecture in two dimensions. Under water deficit (50% of soil water-holding capacity), total root length was strongly reduced but the depth of root foraging and the shape of the root system were less affected, likely to improve water uptake. 14CO2 pulse-chase experiments confirmed that water deficit enhanced carbon (C) export to the roots, as suggested by the increased root-to-shoot ratio. The transcript levels of AtSWEET11 (for sugar will eventually be exported transporter), AtSWEET12, and AtSUC2 (for Suc carrier) genes, all three involved in Suc phloem loading, were significantly up-regulated in leaves of water deficit plants, in accordance with the increase in C export from the leaves to the roots. Interestingly, the transcript levels of AtSUC2 and AtSWEET11 to AtSWEET15 were also significantly higher in stressed roots, underlying the importance of Suc apoplastic unloading in Arabidopsis roots and a putative role for these Suc transporters in Suc unloading. These data demonstrate that, during water deficit, plants respond to growth limitation by allocating relatively more C to the roots to maintain an efficient root system and that a subset of Suc transporters is potentially involved in the flux of C to and in the roots. PMID:26802041

  5. Water Deficit Enhances C Export to the Roots in Arabidopsis thaliana Plants with Contribution of Sucrose Transporters in Both Shoot and Roots.

    PubMed

    Durand, Mickaël; Porcheron, Benoît; Hennion, Nils; Maurousset, Laurence; Lemoine, Rémi; Pourtau, Nathalie

    2016-03-01

    Root high plasticity is an adaptation to its changing environment. Water deficit impairs growth, leading to sugar accumulation in leaves, part of which could be available to roots via sucrose (Suc) phloem transport. Phloem loading is widely described in Arabidopsis (Arabidopsis thaliana), while unloading in roots is less understood. To gain information on leaf-to-root transport, a soil-based culture system was developed to monitor root system architecture in two dimensions. Under water deficit (50% of soil water-holding capacity), total root length was strongly reduced but the depth of root foraging and the shape of the root system were less affected, likely to improve water uptake. (14)CO2 pulse-chase experiments confirmed that water deficit enhanced carbon (C) export to the roots, as suggested by the increased root-to-shoot ratio. The transcript levels of AtSWEET11 (for sugar will eventually be exported transporter), AtSWEET12, and AtSUC2 (for Suc carrier) genes, all three involved in Suc phloem loading, were significantly up-regulated in leaves of water deficit plants, in accordance with the increase in C export from the leaves to the roots. Interestingly, the transcript levels of AtSUC2 and AtSWEET11 to AtSWEET15 were also significantly higher in stressed roots, underlying the importance of Suc apoplastic unloading in Arabidopsis roots and a putative role for these Suc transporters in Suc unloading. These data demonstrate that, during water deficit, plants respond to growth limitation by allocating relatively more C to the roots to maintain an efficient root system and that a subset of Suc transporters is potentially involved in the flux of C to and in the roots. PMID:26802041

  6. Plant-Microbe Communication Enhances Auxin Biosynthesis by a Root-Associated Bacterium, Bacillus amyloliquefaciens SQR9.

    PubMed

    Liu, Yunpeng; Chen, Lin; Zhang, Nan; Li, Zunfeng; Zhang, Guishan; Xu, Yu; Shen, Qirong; Zhang, Ruifu

    2016-04-01

    Mechanisms by which beneficial rhizobacteria promote plant growth include tryptophan-dependent indole-3-acetic acid (IAA) synthesis. The abundance of tryptophan in the rhizosphere, however, may influence the level of benefit provided by IAA-producing rhizobacteria. This study examined the cucumber-Bacillus amyloliquefaciens SQR9 system and found that SQR9, a bacterium previously shown to enhance the growth of cucumber, increased root secretion of tryptophan by three- to fourfold. Using a split-root system, SQR9 colonization of roots in one chamber not only increased tryptophan secretion from the noninoculated roots but also increased the expression of the cucumber tryptophan transport gene but not the anthranilate synthesis gene in those roots. The increased tryptophan in isolated rhizosphere exudates was sufficient to support increased IAA production by SQR9. Moreover, SQR9 colonization of roots in one chamber in the split-root system resulted in sufficient tryptophan production by the other roots to upregulate SQR9 IAA biosynthesis genes, including a 27-fold increase in the indole-3-acetonitrilase gene yhcX during subsequent colonization of those roots. Deletion of yhcX eliminated SQR9-mediated increases in root surface area, likely by reducing IAA-stimulated lateral root growth. This study demonstrates a chemical dialogue between B. amyloliquefaciens and cucumber in which this communication contributes to bacteria-mediated plant-growth enhancement. PMID:26808445

  7. Roots in plant ecology.

    PubMed

    Cody, M L

    1986-09-01

    In 1727 the pioneer vegetation scientist Stephen Hales realized that I much that was of importance to his subject material took place below on ground. A good deal of descriptive work on plant roots and root systems was done in the subsequent two centuries; in crop plants especially, the gross morphology of root systems was well known by the early 20th century. These descriptive studies were extended to natural grasslands by Weaver and his associates and to deserts by Cannon by the second decade of this century, but since that time the study of subterranean growth form appears to have lapsed, as a recent review by Kummerow indicates. Nevertheless, growth form is an important aspect of plant ecology, and subterranean growth form is especially relevant to the study of vegetation in and areas (which is the main subject of this commentary). Moreover, there is a real need for more research to be directed towards understanding plant root systems in general. PMID:21227785

  8. Paenibacillus polymyxa BFKC01 enhances plant iron absorption via improved root systems and activated iron acquisition mechanisms.

    PubMed

    Zhou, Cheng; Guo, Jiansheng; Zhu, Lin; Xiao, Xin; Xie, Yue; Zhu, Jian; Ma, Zhongyou; Wang, Jianfei

    2016-08-01

    Despite the high abundance of iron (Fe) in most earth's soils, Fe is the major limiting factor for plant growth and development due to its low bioavailability. With an increasing recognition that soil microbes play important roles in plant growth, several strains of beneficial rhizobactria have been applied to improve plant nutrient absorption, biomass, and abiotic or biotic stress tolerance. In this study, we report the mechanisms of microbe-induced plant Fe assimilation, in which the plant growth promoting rhizobacteria (PGPR) Paenibacillus polymyxa BFKC01 stimulates plant's Fe acquisition machinery to enhance Fe uptake in Arabidopsis plants. Mechanistic studies show that BFKC01 transcriptionally activates the Fe-deficiency-induced transcription factor 1 (FIT1), thereby up-regulating the expression of IRT1 and FRO2. Furthermore, BFKC01 has been found to induce plant systemic responses with the increased transcription of MYB72, and the biosynthetic pathways of phenolic compounds are also activated. Our data reveal that abundant phenolic compounds are detected in root exudation of the BFKC01-inoculated plants, which efficiently facilitate Fe mobility under alkaline conditions. In addition, BFKC01 can secret auxin and further improved root systems, which enhances the ability of plants to acquire Fe from soils. As a result, BFKC01-inoculated plants have more endogenous Fe and increased photosynthetic capacity under alkaline conditions as compared to control plants. Our results demonstrate the potential roles of BFKC01 in promoting Fe acquisition in plants and underline the intricate integration of microbial signaling in controlling plant Fe acquisition. PMID:27105423

  9. The role of root damage in the chelate-enhanced accumulation of lead by Indian mustard plants.

    PubMed

    Luo, Chunling; Shen, Zhenguo; Li, Xiangdong; Baker, Alan J M

    2006-01-01

    In the present study, increasing ethylenediaminetetraacetic acid (EDTA) concentration from 0 to 0.5 mmol L(-1) resulted in progressive increases in root elongation and in shoot and root dry matter (DM) of Indian mustard seedlings (Brassica juncea. L.) exposed at 0.5 mmol L(-1) of lead (Pb). The highest concentration of Pb in the shoots of Indian mustard reached 1140 mg kg(-1) dry weight (DW) in the treatment with 0.5 mmol L(-1) of Pb + 0.25 mmol L(-1) of EDTA. A significantly positive correlation was found between the concentrations of Pb and EDTA in the shoots of mustard. Roots were pretreated with an MC (methanol:trichloromethane) solution, 0.1 mol L(-1) of HCl, and 65 degrees C hot water. The plants were then exposed to 0.5 mmol L(-1) of Pb + 3 mmol L(-1) of EDTA in solution for 2 d. The pretreatments with MC, HCl, and hot water all increased the concentration of Pb in shoots by 14-, 7-, and 15-fold, respectively, compared with the shoots that had not been pretreated. Therefore, some physiological damage to roots would be useful to enhance the uptake of metal by plants and to minimize the application of doses of chelates in the practical operation of chelate-assisted phytoremediation. PMID:17305306

  10. Exogenous malic and acetic acids reduce cadmium phytotoxicity and enhance cadmium accumulation in roots of sunflower plants.

    PubMed

    Hawrylak-Nowak, Barbara; Dresler, Sławomir; Matraszek, Renata

    2015-09-01

    There is increasing evidence showing that low molecular weight organic acids (LMWOA) are involved in heavy metal resistance mechanisms in plants. The aim of this study was to investigate the effects of exogenous malic (MA) or acetic (AA) acids on the toxicity and accumulation of cadmium (Cd) in sunflower (Helianthus annuus L.). For this purpose, plants were grown in hydroponics under controlled conditions. Single Cd stress (5 μM Cd for 14 days) induced strong phytotoxic effects, as indicated by a decrease in all growth parameters, concentration of photosynthetic pigments, and root activity, as well as a high level of hydrogen peroxide (H2O2) accumulation. Exogenous MA or AA (250 or 500 μM) applied to the Cd-containing medium enhanced the accumulation of Cd by the roots and limited Cd translocation to the shoots. Moreover, the MA or AA applied more or less reduced Cd phytotoxicity by increasing the growth parameters, photosynthetic pigment concentrations, decreasing accumulation of H2O2, and improving the root activity. Of the studied organic acids, MA was much more efficient in mitigation of Cd toxicity than AA, probably by its antioxidant effects, which were stronger than those of AA. Plant response to Cd involved decreased production of endogenous LMWOA, probably as a consequence of severe Cd toxicity. The addition of MA or AA to the medium increased endogenous accumulation of LMWOA, especially in the roots, which could be beneficial for plant metabolism. These results imply that especially MA may be involved in the processes of Cd uptake, translocation, and tolerance in plants. PMID:26115548

  11. Rhizobacterial colonization of roots modulates plant volatile emission and enhances the attraction of a parasitoid wasp to host-infested plants.

    PubMed

    Pangesti, Nurmi; Weldegergis, Berhane T; Langendorf, Benjamin; van Loon, Joop J A; Dicke, Marcel; Pineda, Ana

    2015-08-01

    Beneficial root-associated microbes modify the physiological status of their host plants and affect direct and indirect plant defense against insect herbivores. While the effects of these microbes on direct plant defense against insect herbivores are well described, knowledge of the effect of the microbes on indirect plant defense against insect herbivores is still limited. In this study, we evaluate the role of the rhizobacterium Pseudomonas fluorescens WCS417r in indirect plant defense against the generalist leaf-chewing insect Mamestra brassicae through a combination of behavioral, chemical, and gene-transcriptional approaches. We show that rhizobacterial colonization of Arabidopsis thaliana roots results in an increased attraction of the parasitoid Microplitis mediator to caterpillar-infested plants. Volatile analysis revealed that rhizobacterial colonization suppressed the emission of the terpene (E)-α-bergamotene and the aromatics methyl salicylate and lilial in response to caterpillar feeding. Rhizobacterial colonization decreased the caterpillar-induced transcription of the terpene synthase genes TPS03 and TPS04. Rhizobacteria enhanced both the growth and the indirect defense of plants under caterpillar attack. This study shows that rhizobacteria have a high potential to enhance the biocontrol of leaf-chewing herbivores based on enhanced attraction of parasitoids. PMID:25783487

  12. Tight coupling of root-associated nitrogen fixation and plant photosynthesis in the salt marsh Spartina alterniflora and carbon dioxide enhancement of Nitrogenase activity

    SciTech Connect

    Whiting, G.J.; Gandy, E.L.; Yoch, D.C.

    1986-07-01

    The coupling of root-associated nitrogen fixation and plant photosynthesis was examined in the salt marsh grass Spartina alterniflora. In both field experiments and hydroponic assay chambers, nitrogen fixation associated with the roots was rapidly enhanced by stimulating plant photosynthesis. A kinetic analysis of acetylene reduction activity (ARA) showed that a five-to-sixfold stimulation occurred within 10 to 60 min after the plant leaves were exposed to light or increase CO/sub 2/ concentrations (with the light held constant). In field experiments, CO/sub 2/ enrichment increased plant-associated ARA by 27%. Further evidence of the dependence of ARA on plant photosynthate was obtained when activity in excised roots was shown to decrease after young greenhouse plants were placed in the dark. Seasonal variation in the ARA of excised plant roots from field cores appears to be related to the annual cycle of net photosynthesis in S. alterniflora.

  13. Nano titania aided clustering and adhesion of beneficial bacteria to plant roots to enhance crop growth and stress management

    PubMed Central

    Palmqvist, N. G. M.; Bejai, S.; Meijer, J.; Seisenbaeva, G. A.; Kessler, V. G.

    2015-01-01

    A novel use of Titania nanoparticles as agents in the nano interface interaction between a beneficial plant growth promoting bacterium (Bacillus amyloliquefaciens UCMB5113) and oilseed rape plants (Brassica napus) for protection against the fungal pathogen Alternaria brassicae is presented. Two different TiO2 nanoparticle material were produced by the Sol-Gel approach, one using the patented Captigel method and the other one applying TiBALDH precursor. The particles were characterized by transmission electron microscopy, thermogravimetric analysis, X-ray diffraction, dynamic light scattering and nano particle tracking analysis. Scanning electron microscopy showed that the bacterium was living in clusters on the roots and the combined energy-dispersive X-ray spectroscopy analysis revealed that titanium was present in these cluster formations. Confocal laser scanning microscopy further demonstrated an increased bacterial colonization of Arabidopsis thaliana roots and a semi-quantitative microscopic assay confirmed an increased bacterial adhesion to the roots. An increased amount of adhered bacteria was further confirmed by quantitative fluorescence measurements. The degree of infection by the fungus was measured and quantified by real-time-qPCR. Results showed that Titania nanoparticles increased adhesion of beneficial bacteria on to the roots of oilseed rape and protected the plants against infection. PMID:25970693

  14. Nano titania aided clustering and adhesion of beneficial bacteria to plant roots to enhance crop growth and stress management.

    PubMed

    Palmqvist, N G M; Bejai, S; Meijer, J; Seisenbaeva, G A; Kessler, V G

    2015-01-01

    A novel use of Titania nanoparticles as agents in the nano interface interaction between a beneficial plant growth promoting bacterium (Bacillus amyloliquefaciens UCMB5113) and oilseed rape plants (Brassica napus) for protection against the fungal pathogen Alternaria brassicae is presented. Two different TiO2 nanoparticle material were produced by the Sol-Gel approach, one using the patented Captigel method and the other one applying TiBALDH precursor. The particles were characterized by transmission electron microscopy, thermogravimetric analysis, X-ray diffraction, dynamic light scattering and nano particle tracking analysis. Scanning electron microscopy showed that the bacterium was living in clusters on the roots and the combined energy-dispersive X-ray spectroscopy analysis revealed that titanium was present in these cluster formations. Confocal laser scanning microscopy further demonstrated an increased bacterial colonization of Arabidopsis thaliana roots and a semi-quantitative microscopic assay confirmed an increased bacterial adhesion to the roots. An increased amount of adhered bacteria was further confirmed by quantitative fluorescence measurements. The degree of infection by the fungus was measured and quantified by real-time-qPCR. Results showed that Titania nanoparticles increased adhesion of beneficial bacteria on to the roots of oilseed rape and protected the plants against infection. PMID:25970693

  15. Nano titania aided clustering and adhesion of beneficial bacteria to plant roots to enhance crop growth and stress management

    NASA Astrophysics Data System (ADS)

    Palmqvist, N. G. M.; Bejai, S.; Meijer, J.; Seisenbaeva, G. A.; Kessler, V. G.

    2015-05-01

    A novel use of Titania nanoparticles as agents in the nano interface interaction between a beneficial plant growth promoting bacterium (Bacillus amyloliquefaciens UCMB5113) and oilseed rape plants (Brassica napus) for protection against the fungal pathogen Alternaria brassicae is presented. Two different TiO2 nanoparticle material were produced by the Sol-Gel approach, one using the patented Captigel method and the other one applying TiBALDH precursor. The particles were characterized by transmission electron microscopy, thermogravimetric analysis, X-ray diffraction, dynamic light scattering and nano particle tracking analysis. Scanning electron microscopy showed that the bacterium was living in clusters on the roots and the combined energy-dispersive X-ray spectroscopy analysis revealed that titanium was present in these cluster formations. Confocal laser scanning microscopy further demonstrated an increased bacterial colonization of Arabidopsis thaliana roots and a semi-quantitative microscopic assay confirmed an increased bacterial adhesion to the roots. An increased amount of adhered bacteria was further confirmed by quantitative fluorescence measurements. The degree of infection by the fungus was measured and quantified by real-time-qPCR. Results showed that Titania nanoparticles increased adhesion of beneficial bacteria on to the roots of oilseed rape and protected the plants against infection.

  16. Root Traits and Phenotyping Strategies for Plant Improvement.

    PubMed

    Paez-Garcia, Ana; Motes, Christy M; Scheible, Wolf-Rüdiger; Chen, Rujin; Blancaflor, Elison B; Monteros, Maria J

    2015-01-01

    Roots are crucial for nutrient and water acquisition and can be targeted to enhance plant productivity under a broad range of growing conditions. A current challenge for plant breeding is the limited ability to phenotype and select for desirable root characteristics due to their underground location. Plant breeding efforts aimed at modifying root traits can result in novel, more stress-tolerant crops and increased yield by enhancing the capacity of the plant for soil exploration and, thus, water and nutrient acquisition. Available approaches for root phenotyping in laboratory, greenhouse and field encompass simple agar plates to labor-intensive root digging (i.e., shovelomics) and soil boring methods, the construction of underground root observation stations and sophisticated computer-assisted root imaging. Here, we summarize root architectural traits relevant to crop productivity, survey root phenotyping strategies and describe their advantages, limitations and practical value for crop and forage breeding programs. PMID:27135332

  17. Root Traits and Phenotyping Strategies for Plant Improvement

    PubMed Central

    Paez-Garcia, Ana; Motes, Christy M.; Scheible, Wolf-Rüdiger; Chen, Rujin; Blancaflor, Elison B.; Monteros, Maria J.

    2015-01-01

    Roots are crucial for nutrient and water acquisition and can be targeted to enhance plant productivity under a broad range of growing conditions. A current challenge for plant breeding is the limited ability to phenotype and select for desirable root characteristics due to their underground location. Plant breeding efforts aimed at modifying root traits can result in novel, more stress-tolerant crops and increased yield by enhancing the capacity of the plant for soil exploration and, thus, water and nutrient acquisition. Available approaches for root phenotyping in laboratory, greenhouse and field encompass simple agar plates to labor-intensive root digging (i.e., shovelomics) and soil boring methods, the construction of underground root observation stations and sophisticated computer-assisted root imaging. Here, we summarize root architectural traits relevant to crop productivity, survey root phenotyping strategies and describe their advantages, limitations and practical value for crop and forage breeding programs. PMID:27135332

  18. Tomato transgenic plants expressing hairpin construct of a nematode protease gene conferred enhanced resistance to root-knot nematodes

    PubMed Central

    Dutta, Tushar K.; Papolu, Pradeep K.; Banakar, Prakash; Choudhary, Divya; Sirohi, Anil; Rao, Uma

    2015-01-01

    Root-knot nematodes (Meloidogyne incognita) cause substantial yield losses in vegetables worldwide, and are difficult to manage. Continuous withdrawal of environmentally-harmful nematicides from the global market warrants the need for novel nematode management strategies. Utility of host-delivered RNAi has been demonstrated in several plants (Arabidopsis, tobacco, and soybean) that exhibited resistance against root-knot and cyst nematodes. Herein, a M. incognita-specific protease gene, cathepsin L cysteine proteinase (Mi-cpl-1), was targeted to generate tomato transgenic lines to evaluate the genetically modified nematode resistance. In vitro knockdown of Mi-cpl-1 gene led to the reduced attraction and penetration of M. incognita in tomato, suggesting the involvement of Mi-cpl-1 in nematode parasitism. Transgenic expression of the RNAi construct of Mi-cpl-1 gene resulted in 60–80% reduction in infection and multiplication of M. incognita in tomato. Evidence for in vitro and in vivo silencing of Mi-cpl-1 was confirmed by expression analysis using quantitative PCR. Our study demonstrates that Mi-cpl-1 plays crucial role during plant-nematode interaction and plant-mediated downregulation of this gene elicits detrimental effect on M. incognita development, reinforcing the potential of RNAi technology for management of phytonematodes in crop plants. PMID:25883594

  19. Economic strategies of plant absorptive roots vary with root diameter

    NASA Astrophysics Data System (ADS)

    Kong, D. L.; Wang, J. J.; Kardol, P.; Wu, H. F.; Zeng, H.; Deng, X. B.; Deng, Y.

    2016-01-01

    Plant roots typically vary along a dominant ecological axis, the root economics spectrum, depicting a tradeoff between resource acquisition and conservation. For absorptive roots, which are mainly responsible for resource acquisition, we hypothesized that root economic strategies differ with increasing root diameter. To test this hypothesis, we used seven plant species (a fern, a conifer, and five angiosperms from south China) for which we separated absorptive roots into two categories: thin roots (thickness of root cortex plus epidermis < 247 µm) and thick roots. For each category, we analyzed a range of root traits related to resource acquisition and conservation, including root tissue density, different carbon (C), and nitrogen (N) fractions (i.e., extractive, acid-soluble, and acid-insoluble fractions) as well as root anatomical traits. The results showed significant relationships among root traits indicating an acquisition-conservation tradeoff for thin absorptive roots while no such trait relationships were found for thick absorptive roots. Similar results were found when reanalyzing data of a previous study including 96 plant species. The contrasting economic strategies between thin and thick absorptive roots, as revealed here, may provide a new perspective on our understanding of the root economics spectrum.

  20. Enhanced utilization of labile substrate in the soil in absence of plant C input through roots and ectomycorrhizal fungi

    NASA Astrophysics Data System (ADS)

    Voke, N. R.; Subke, J.-A.; Nair, R.; Ineson, P.

    2009-04-01

    Soils form a significant store of carbon (C) in terrestrial ecosystems, and hold the potential to mitigate or enforce global environmental change. The direction of such climate driven feedbacks depends on the way in which processes of C sequestration and release from soils are affected by changes in environmental conditions. There is an increasing realization that complex interactions between plants and soil organisms are crucial for the stability of soil organic matter (SOM). However, we still lack a good understanding of the nature of this interdependence and its likely environmental responses. The aim of this study is to investigate how 13C labeled glucose is utilized in the presence or absence of inputs from plants through roots. Specifically we aim to investigate the importance of EM fungi in the control of carbon cycling in forest ecosystems and the influence of EM fungi on the activity of rhizospheric soil microorganisms. We installed four replicates each of three different collar treatments in a 18-year old Lodgepole pine (Pinus contorta) stand near York (NE England). These consisted of deep soil collars with four windows just below surface level covered either by 1 m mesh in order to exclude both roots and hyphae (treatment S) or 41 m mesh to exclude just roots (treatment M). The third set of collars was inserted to a shallow depth of c. 1.5 cm, thus allowing natural access by roots and hyphae (treatment R). Soil moisture levels were controlled through the exclusion of natural throughfall using PVC shields above the collars. Throughfall collectors were positioned in the experimental plot and an average amount of throughfall was added to each of the soil cores weekly. Six months following collar insertion, we applied 13C-labelled glucose to all collars. CO2 flux (RS) from all collars as well as its isotopic composition was measured continuously using a field-deployed mass spectrometer, and we estimate microbial utilization of the glucose using the return

  1. Plant growth-promoting rhizobacteria and root system functioning

    PubMed Central

    Vacheron, Jordan; Desbrosses, Guilhem; Bouffaud, Marie-Lara; Touraine, Bruno; Moënne-Loccoz, Yvan; Muller, Daniel; Legendre, Laurent; Wisniewski-Dyé, Florence; Prigent-Combaret, Claire

    2013-01-01

    The rhizosphere supports the development and activity of a huge and diversified microbial community, including microorganisms capable to promote plant growth. Among the latter, plant growth-promoting rhizobacteria (PGPR) colonize roots of monocots and dicots, and enhance plant growth by direct and indirect mechanisms. Modification of root system architecture by PGPR implicates the production of phytohormones and other signals that lead, mostly, to enhanced lateral root branching and development of root hairs. PGPR also modify root functioning, improve plant nutrition and influence the physiology of the whole plant. Recent results provided first clues as to how PGPR signals could trigger these plant responses. Whether local and/or systemic, the plant molecular pathways involved remain often unknown. From an ecological point of view, it emerged that PGPR form coherent functional groups, whose rhizosphere ecology is influenced by a myriad of abiotic and biotic factors in natural and agricultural soils, and these factors can in turn modulate PGPR effects on roots. In this paper, we address novel knowledge and gaps on PGPR modes of action and signals, and highlight recent progress on the links between plant morphological and physiological effects induced by PGPR. We also show the importance of taking into account the size, diversity, and gene expression patterns of PGPR assemblages in the rhizosphere to better understand their impact on plant growth and functioning. Integrating mechanistic and ecological knowledge on PGPR populations in soil will be a prerequisite to develop novel management strategies for sustainable agriculture. PMID:24062756

  2. Earliest rooting system and root : shoot ratio from a new Zosterophyllum plant.

    PubMed

    Hao, Shougang; Xue, Jinzhuang; Guo, Dali; Wang, Deming

    2010-01-01

    The enhanced chemical weathering by rooted vascular plants during the Silurian-Devonian period played a crucial role in altering global biogeochemical cycles and atmospheric environments; however, the documentation of early root morphology and physiology is scarce because the existing fossils are mostly incomplete. Here, we report an entire, uprooted specimen of a new Zosterophyllum Penhallow, named as Z. shengfengense, from the Early Devonian Xitun Formation (Lochkovian, c. 413 Myr old) of Yunnan, south China. This plant has the most ancient known record of a rooting system. The plant consists of aerial axes of 98 mm in height, showing a tufted habit, and a rhizome bearing a fibrous-like rooting system, c. 20 mm in length. The rhizome shows masses of branchings, which produce upwardly directed aerial axes and downwardly directed root-like axes. The completeness of Z. shengfengense made it possible to estimate the biomass allocation and root : shoot ratio. The root : shoot ratio of this early plant is estimated at a mean value of 0.028, and the root-like axes constitute only c. 3% of the total biomass. Zosterophyllum shengfengense was probably a semi-aquatic plant with efficient water use or a strong uptake capacity of the root-like axes. PMID:19825018

  3. Salt stress signals shape the plant root.

    PubMed

    Galvan-Ampudia, Carlos S; Testerink, Christa

    2011-06-01

    Plants use different strategies to deal with high soil salinity. One strategy is activation of pathways that allow the plant to export or compartmentalise salt. Relying on their phenotypic plasticity, plants can also adjust their root system architecture (RSA) and the direction of root growth to avoid locally high salt concentrations. Here, we highlight RSA responses to salt and osmotic stress and the underlying mechanisms. A model is presented that describes how salinity affects auxin distribution in the root. Possible intracellular signalling pathways linking salinity to root development and direction of root growth are discussed. These involve perception of high cytosolic Na+ concentrations in the root, activation of lipid signalling and protein kinase activity and modulation of endocytic pathways. PMID:21511515

  4. Maize root characteristis that enhance flooding tolerance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Plant root systems have several cellular and molecular adaptations that are important in reducing stress caused by flooding. Of these, two physical properties of root systems provide an initial barrier toward the avoidance of stress. These are the presence of aerenchyma cells and rapid adventitious ...

  5. Plant root-microbe communication in shaping root microbiomes.

    PubMed

    Lareen, Andrew; Burton, Frances; Schäfer, Patrick

    2016-04-01

    A growing body of research is highlighting the impacts root-associated microbial communities can have on plant health and development. These impacts can include changes in yield quantity and quality, timing of key developmental stages and tolerance of biotic and abiotic stresses. With such a range of effects it is clear that understanding the factors that contribute to a plant-beneficial root microbiome may prove advantageous. Increasing demands for food by a growing human population increases the importance and urgency of understanding how microbiomes may be exploited to increase crop yields and reduce losses caused by disease. In addition, climate change effects may require novel approaches to overcoming abiotic stresses such as drought and salinity as well as new emerging diseases. This review discusses current knowledge on the formation and maintenance of root-associated microbial communities and plant-microbe interactions with a particular emphasis on the effect of microbe-microbe interactions on the shape of microbial communities at the root surface. Further, we discuss the potential for root microbiome modification to benefit agriculture and food production. PMID:26729479

  6. Apoplastic interactions between plants and plant root intruders.

    PubMed

    Mitsumasu, Kanako; Seto, Yoshiya; Yoshida, Satoko

    2015-01-01

    Numerous pathogenic or parasitic organisms attack plant roots to obtain nutrients, and the apoplast including the plant cell wall is where the plant cell meets such organisms. Root parasitic angiosperms and nematodes are two distinct types of plant root parasites but share some common features in their strategies for breaking into plant roots. Striga and Orobanche are obligate root parasitic angiosperms that cause devastating agricultural problems worldwide. Parasitic plants form an invasion organ called a haustorium, where plant cell wall degrading enzymes (PCWDEs) are highly expressed. Plant-parasitic nematodes are another type of agriculturally important plant root parasite. These nematodes breach the plant cell walls by protruding a sclerotized stylet from which PCWDEs are secreted. Responding to such parasitic invasion, host plants activate their own defense responses against parasites. Endoparasitic nematodes secrete apoplastic effectors to modulate host immune responses and to facilitate the formation of a feeding site. Apoplastic communication between hosts and parasitic plants also contributes to their interaction. Parasitic plant germination stimulants, strigolactones, are recently identified apoplastic signals that are transmitted over long distances from biosynthetic sites to functioning sites. Here, we discuss recent advances in understanding the importance of apoplastic signals and cell walls for plant-parasite interactions. PMID:26322059

  7. Constitutive expression of pathogen-inducible OsWRKY31 enhances disease resistance and affects root growth and auxin response in transgenic rice plants.

    PubMed

    Zhang, Juan; Peng, Youliang; Guo, Zejian

    2008-04-01

    WRKY transcription factors have many regulatory roles in response to biotic and abiotic stresses. In this study, we isolated a rice WRKY gene (OsWRKY31) that is induced by the rice blast fungus Magnaporthe grisea and auxin. This gene encodes a polypeptide of 211 amino-acid residues and belongs to a subgroup of the rice WRKY gene family that probably originated after the divergence of monocot and dicot plants. OsWRKY31 was found to be localized to the nucleus of onion epidermis cells to transiently express OsWRKY31-eGFP fusion protein. Analysis of OsWRKY31 and its mutants fused with a Gal4 DNA-binding domain indicated that OsWRKY31 has transactivation activity in yeast. Overexpression of the OsWRKY31 gene was found to enhance resistance against infection with M. grisea, and the transgenic lines exhibited reduced lateral root formation and elongation compared with wild-type and RNAi plants. The lines with overexpression showed constitutive expression of many defense-related genes, such as PBZ1 and OsSci2, as well as early auxin-response genes, such as OsIAA4 and OsCrl1 genes. Furthermore, the plants with overexpression were less sensitive to exogenously supplied IBA, NAA and 2,4-D at high concentrations, suggesting that overexpression of the OsWRKY31 gene might alter the auxin response or transport. These results also suggest that OsWRKY31 might be a common component in the signal transduction pathways of the auxin response and the defense response in rice. PMID:18071364

  8. Sporulation on plant roots by Phytophthora ramorum

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Phytophthora ramorum has been shown to infect the roots of many of the pathogen’s foliar hosts. Methods of detecting inoculum in runoff and of quantifying root colonization were tested using Viburnum tinus, Camellia oleifera, Quercus prinus, Umbellularia californica, and Epilobium ciliatum. Plants...

  9. Apoplastic interactions between plants and plant root intruders

    PubMed Central

    Mitsumasu, Kanako; Seto, Yoshiya; Yoshida, Satoko

    2015-01-01

    Numerous pathogenic or parasitic organisms attack plant roots to obtain nutrients, and the apoplast including the plant cell wall is where the plant cell meets such organisms. Root parasitic angiosperms and nematodes are two distinct types of plant root parasites but share some common features in their strategies for breaking into plant roots. Striga and Orobanche are obligate root parasitic angiosperms that cause devastating agricultural problems worldwide. Parasitic plants form an invasion organ called a haustorium, where plant cell wall degrading enzymes (PCWDEs) are highly expressed. Plant-parasitic nematodes are another type of agriculturally important plant root parasite. These nematodes breach the plant cell walls by protruding a sclerotized stylet from which PCWDEs are secreted. Responding to such parasitic invasion, host plants activate their own defense responses against parasites. Endoparasitic nematodes secrete apoplastic effectors to modulate host immune responses and to facilitate the formation of a feeding site. Apoplastic communication between hosts and parasitic plants also contributes to their interaction. Parasitic plant germination stimulants, strigolactones, are recently identified apoplastic signals that are transmitted over long distances from biosynthetic sites to functioning sites. Here, we discuss recent advances in understanding the importance of apoplastic signals and cell walls for plant–parasite interactions. PMID:26322059

  10. Random River Fluctuations Shape the Root Profile of Riparian Plants

    NASA Astrophysics Data System (ADS)

    Perona, P.; Tron, S.; Gorla, L.; Schwarz, M.; Laio, F.; Ridolfi, L.

    2015-12-01

    Plant roots are recognized to play a key role in the riparian ecosystems: they contribute to the plant as well as to the streambank and bedforms stability, help to enhance the water quality of the river, and sustain the belowground biodiversity. The complexity of the root-system architecture recalls their remarkable ability to respond to environmental conditions, notably including soil heterogeneity, resource availability, and climate. In fluvial environments where nutrient availability is not a limiting factor for plant to grow, the root growth of phreatophytic plants is strongly influenced by water and oxygen availability in the soil. In this work, we demonstrate that the randomness of water table fluctuations, determined by streamflow stochastic variability, is likely to be the main driver for the root development strategy of riparian plants. A collection of root measurements from field and outdoor controlled experiments is used to demonstrate that the vertical root density distribution can be described by a simple analytical expression, whose parameters are linked to properties of soil, plant and water table fluctuations. This physically-based expression is able to predict riparian plant roots adaptability to different hydrological and pedologic scenarios in riverine environments. Hence, this model has great potential towards the comprehension of the effects of future climate and environmental changing conditions on plant adaptation and river ecomorphodynamic processes. Finally, we present an open access graphical user interface that we developed in order to estimate the vertical root distribution in fluvial environments and to make the model easily available to a wider scientific and professional audience.

  11. Microbial Products Trigger Amino Acid Exudation from Plant Roots1

    PubMed Central

    Phillips, Donald A.; Fox, Tama C.; King, Maria D.; Bhuvaneswari, T.V.; Teuber, Larry R.

    2004-01-01

    Plants naturally cycle amino acids across root cell plasma membranes, and any net efflux is termed exudation. The dominant ecological view is that microorganisms and roots passively compete for amino acids in the soil solution, yet the innate capacity of roots to recover amino acids present in ecologically relevant concentrations is unknown. We find that, in the absence of culturable microorganisms, the influx rates of 16 amino acids (each supplied at 2.5 μm) exceed efflux rates by 5% to 545% in roots of alfalfa (Medicago sativa), Medicago truncatula, maize (Zea mays), and wheat (Triticum aestivum). Several microbial products, which are produced by common soil microorganisms such as Pseudomonas bacteria and Fusarium fungi, significantly enhanced the net efflux (i.e. exudation) of amino acids from roots of these four plant species. In alfalfa, treating roots with 200 μm phenazine, 2,4-diacetylphloroglucinol, or zearalenone increased total net efflux of 16 amino acids 200% to 2,600% in 3 h. Data from 15N tests suggest that 2,4-diacetylphloroglucinol blocks amino acid uptake, whereas zearalenone enhances efflux. Thus, amino acid exudation under normal conditions is a phenomenon that probably reflects both active manipulation and passive uptake by microorganisms, as well as diffusion and adsorption to soil, all of which help overcome the innate capacity of plant roots to reabsorb amino acids. The importance of identifying potential enhancers of root exudation lies in understanding that such compounds may represent regulatory linkages between the larger soil food web and the internal carbon metabolism of the plant. PMID:15347793

  12. Plant Hormones: How They Affect Root Formation.

    ERIC Educational Resources Information Center

    Reinhard, Diana Hereda

    This science study aid, produced by the U.S. Department of Agriculture, includes a series of plant rooting activities for secondary science classes. The material in the pamphlet is written for students and includes background information on plant hormones, a vocabulary list, and five learning activities. Objectives, needed materials, and…

  13. Assembly line plants take root

    SciTech Connect

    Comis, D.; Wood, M.

    1986-04-01

    This paper discussed tissue-culture propagation of sugarcane, apple trees, peach trees, citrus, orchids, data palms, and carrots. Tissue-culture propagation is a term used for a variety of techniques used to grow or genetically modify, preserve, or study plant parts in laboratories, from tissue or even a single cell. The author examined the benefits and commercial applications of this propagation process.

  14. Fate of polycyclic aromatic hydrocarbons in plant-soil systems: Plant responses to a chemical stress in the root zone

    SciTech Connect

    Hoylman, A.M.; Walton, B.T.

    1994-01-01

    Under laboratory conditions selected to maximize root uptake, plant tissue distribution of PAH-derived {sup 14}C was largely limited to root tissue of Malilotus alba. These results suggest that plant uptake of PAHs from contaminated soil via roots, and translocation to aboveground plant tissues (stems and leaves), is a limited mechanism for transport into terrestrial food chains. However, these data also indicate that root surface sorption of PAHs may be important for plants grown in soils containing elevated concentration PAHs. Root surface sorption of PAHs may be an important route of exposure for plants in soils containing elevated concentrations of PAHS. Consequently, the root-soil interface may be the site of plant-microbial interactions in response to a chemical stress. In this study, evidence of a shift in carbon allocation to the root zone of plants exposed to phenanthrene and corresponding increases in soil respiration and heterotrophic plate counts provide evidence of a plant-microbial response to a chemical stress. The results of this study establish the importance of the root-soil interface for plants growing in PAH contaminated soil and indicate the existence of plant-microbial interactions in response to a chemical stress. These results may provide new avenues of inquiry for studies of plant toxicology, plant-microbial interactions in the rhizosphere, and environmental fates of soil contaminants. In addition, the utilization of plants to enhance the biodegradation of soil contaminants may require evaluation of plant physiological changes and plant shifts in resource allocation.

  15. Enhanced gravitropism of roots with a disrupted cap actin cytoskeleton

    NASA Technical Reports Server (NTRS)

    Hou, Guichuan; Mohamalawari, Deepti R.; Blancaflor, Elison B.

    2003-01-01

    The actin cytoskeleton has been proposed to be a major player in plant gravitropism. However, understanding the role of actin in this process is far from complete. To address this problem, we conducted an analysis of the effect of Latrunculin B (Lat B), a potent actin-disrupting drug, on root gravitropism using various parameters that included detailed curvature kinetics, estimation of gravitropic sensitivity, and monitoring of curvature development after extended clinorotation. Lat B treatment resulted in a promotion of root curvature after a 90 degrees reorientation in three plant species tested. More significantly, the sensitivity of maize (Zea mays) roots to gravity was enhanced after actin disruption, as determined from a comparison of presentation time of Lat B-treated versus untreated roots. A short 10-min gravistimulus followed by extended rotation on a 1-rpm clinostat resulted in extensive gravitropic responses, manifested as curvature that often exceeded 90 degrees. Application of Lat B to the cap or elongation zone of maize roots resulted in the disruption of the actin cytoskeleton, which was confined to the area of localized Lat B application. Only roots with Lat B applied to the cap displayed the strong curvature responses after extended clinorotation. Our study demonstrates that disrupting the actin cytoskeleton in the cap leads to the persistence of a signal established by a previous gravistimulus. Therefore, actin could function in root gravitropism by providing a mechanism to regulate the proliferation of a gravitropic signal originating from the cap to allow the root to attain its correct orientation or set point angle.

  16. The evolutionary root of flowering plants.

    PubMed

    Goremykin, Vadim V; Nikiforova, Svetlana V; Biggs, Patrick J; Zhong, Bojian; Delange, Peter; Martin, William; Woetzel, Stefan; Atherton, Robin A; McLenachan, Patricia A; Lockhart, Peter J

    2013-01-01

    Correct rooting of the angiosperm radiation is both challenging and necessary for understanding the origins and evolution of physiological and phenotypic traits in flowering plants. The problem is known to be difficult due to the large genetic distance separating flowering plants from other seed plants and the sparse taxon sampling among basal angiosperms. Here, we provide further evidence for concern over substitution model misspecification in analyses of chloroplast DNA sequences. We show that support for Amborella as the sole representative of the most basal angiosperm lineage is founded on sequence site patterns poorly described by time-reversible substitution models. Improving the fit between sequence data and substitution model identifies Trithuria, Nymphaeaceae, and Amborella as surviving relatives of the most basal lineage of flowering plants. This finding indicates that aquatic and herbaceous species dominate the earliest extant lineage of flowering plants. [; ; ; ; ; .]. PMID:22851550

  17. Functional traits and root morphology of alpine plants

    PubMed Central

    Pohl, Mandy; Stroude, Raphaël; Buttler, Alexandre; Rixen, Christian

    2011-01-01

    Background and Aims Vegetation has long been recognized to protect the soil from erosion. Understanding species differences in root morphology and functional traits is an important step to assess which species and species mixtures may provide erosion control. Furthermore, extending classification of plant functional types towards root traits may be a useful procedure in understanding important root functions. Methods In this study, pioneer data on traits of alpine plant species, i.e. plant height and shoot biomass, root depth, horizontal root spreading, root length, diameter, tensile strength, plant age and root biomass, from a disturbed site in the Swiss Alps are presented. The applicability of three classifications of plant functional types (PFTs), i.e. life form, growth form and root type, was examined for above- and below-ground plant traits. Key Results Plant traits differed considerably among species even of the same life form, e.g. in the case of total root length by more than two orders of magnitude. Within the same root diameter, species differed significantly in tensile strength: some species (Geum reptans and Luzula spicata) had roots more than twice as strong as those of other species. Species of different life forms provided different root functions (e.g. root depth and horizontal root spreading) that may be important for soil physical processes. All classifications of PFTs were helpful to categorize plant traits; however, the PFTs according to root type explained total root length far better than the other PFTs. Conclusions The results of the study illustrate the remarkable differences between root traits of alpine plants, some of which cannot be assessed from simple morphological inspection, e.g. tensile strength. PFT classification based on root traits seems useful to categorize plant traits, even though some patterns are better explained at the individual species level. PMID:21795278

  18. Advancements in Root Growth Measurement Technologies and Observation Capabilities for Container-Grown Plants

    PubMed Central

    Judd, Lesley A.; Jackson, Brian E.; Fonteno, William C.

    2015-01-01

    The study, characterization, observation, and quantification of plant root growth and root systems (Rhizometrics) has been and remains an important area of research in all disciplines of plant science. In the horticultural industry, a large portion of the crops grown annually are grown in pot culture. Root growth is a critical component in overall plant performance during production in containers, and therefore it is important to understand the factors that influence and/or possible enhance it. Quantifying root growth has varied over the last several decades with each method of quantification changing in its reliability of measurement and variation among the results. Methods such as root drawings, pin boards, rhizotrons, and minirhizotrons initiated the aptitude to measure roots with field crops, and have been expanded to container-grown plants. However, many of the published research methods are monotonous and time-consuming. More recently, computer programs have increased in use as technology advances and measuring characteristics of root growth becomes easier. These programs are instrumental in analyzing various root growth characteristics, from root diameter and length of individual roots to branching angle and topological depth of the root architecture. This review delves into the expanding technologies involved with expertly measuring root growth of plants in containers, and the advantages and disadvantages that remain. PMID:27135334

  19. Plant nutrition: root transporters on the move.

    PubMed

    Zelazny, Enric; Vert, Grégory

    2014-10-01

    Nutrient and water uptake from the soil is essential for plant growth and development. In the root, absorption and radial transport of nutrients and water toward the vascular tissues is achieved by a battery of specialized transporters and channels. Modulating the amount and the localization of these membrane transport proteins appears as a way to drive their activity and is essential to maintain nutrient homeostasis in plants. This control first involves the delivery of newly synthesized proteins to the plasma membrane by establishing check points along the secretory pathway, especially during the export from the endoplasmic reticulum. Plasma membrane-localized transport proteins are internalized through endocytosis followed by recycling to the cell surface or targeting to the vacuole for degradation, hence constituting another layer of control. These intricate mechanisms are often regulated by nutrient availability, stresses, and endogenous cues, allowing plants to rapidly adjust to their environment and adapt their development. PMID:25034018

  20. [Induction of polyploid in hairy roots of Nicotiana tabacum and its plant regeneration].

    PubMed

    Hou, Lili; Shi, Heping; Yu, Wu; Tsang, Po Keung Eric; Chow, Cheuk Fai Stephen

    2014-04-01

    By genetic transformation with Agrobacterum rhizogenes and artificial chromosome doubling techniques, we studied the induction of hairy roots and their polyploidization, and subsequent plant regeneration and nicotine determination to enhance the content of nicotine in Nicotiana tabacum. The results show that hairy roots could be induced from the basal surface of leaf explants of N. tabacum 8 days after inoculation with Agrobacterium rhizogenes ATCC15834. The percentage of the rooting leaf explants was 100% 15 days after inoculation. The hairy roots could grow rapidly and autonomously on solid or liquid phytohormones-free MS medium. The transformation was confirmed by PCR amplification of rol gene of Ri plasmid and paper electrophoresis of opines from N. tabacum hairy roots. The highest rate of polyploidy induction, more than 64.71%, was obtained after treatment of hairy roots with 0.1% colchicine for 36 h. The optimum medium for plant regeneration from polyploid hairy roots was MS+2.0 mg/L 6-BA +0.2 mg/L NAA. Compared with the control diploid plants, the hairy roots-regenerated plants had weak apical dominance, more axillary buds and more narrow leaves; whereas the polyploid hairy root-regenerated plants had thicker stems, shorter internodes and the colour, width and thickness of leaves were significantly higher than that of the control. Observation of the number of chromosomes in their root tip cells reveals that the obtained polyploid regenerated plants were tetraploidy, with 96 (4n = 96) chromosomes. Pot-grown experiments showed compared to the control, the flowering was delayed by 21 days in diploid hairy roots-regenerated plants and polyploid hairy root-regenerated plants. GC-MS detection shows that the content of nicotine in polyploid plants was about 6.90 and 4.57 times the control and the diploid hairy roots-regenerated plants, respectively. PMID:25195248

  1. Rooting depths of plants relative to biological and environmental factors

    SciTech Connect

    Foxx, T S; Tierney, G D; Williams, J M

    1984-11-01

    In 1981 to 1982 an extensive bibliographic study was completed to document rooting depths of native plants in the United States. The data base presently contains 1034 citations with approximately 12,000 data elements. In this paper the data were analyzed for rooting depths as related to life form, soil type, geographical region, root type, family, root depth to shoot height ratios, and root depth to root lateral ratios. Average rooting depth and rooting frequencies were determined and related to present low-level waste site maintenance.

  2. [Induction of polyploid hairy roots and its plant regeneration in Pogostemon cablin].

    PubMed

    Shi, Heping; Yu, Wu; Zhang, Guopeng; Tsang, Pokeung Eric; Chow, Cheuk Fai Stephen

    2014-08-01

    Abstract: In order to enhance the content of secondary metabolites patchouli alcohol in Pogostemon cablin, we induced polyploid hairy roots and their plant regeneration, and determined the content of patchouli alcohol through artificial chromosome doubling with colchicine. The highest rate of polyploidy induction was more than 40% when hairy roots were treated with 0.05% colchicine for 36 h. The obtained polyploid hairy roots formed adventitious shoots when cultured in an MS medium with 6-BA 0.2 mg/L and NAA 0.1 mg/L for 60 d. Compared with the control diploid plants, the polyploid hairy root-regenerated plants of P. cablin had more developed root systems, thicker stems, shorter internodes and longer, wider and thicker leaves. Observation of the chromosome number in their root tip cells reveals that the obtained polyploid regenerated plants were tetraploidy, with 128 (4n = 128) chromosomes. The leaves contained around twice as many stomatal guard cells and chloroplasts as the controls, but the stomatal density declined with increasing ploidy. The stomatal density in diploid plants was around 1.67 times of that in polyploid plants. GC-MS analysis shows that the content of patchouli alcholol in the hairy root-derived polyploid plants was about 4.25 mg/g dry weight, which was 2.3 times of that in diploid plants. The present study demonstrates that polyploidization of hairy roots can stimulate the content of patchouli alcholol in medicinal plant of P. cablin. PMID:25507476

  3. [Induction of polyploid hairy roots and its plant regeneration in Pogostemon cablin].

    PubMed

    Shi, Heping; Yu, Wu; Zhang, Guopeng; Tsang, Pokeung Eric; Chow, Cheuk Fai Stephen

    2014-08-01

    Abstract: In order to enhance the content of secondary metabolites patchouli alcohol in Pogostemon cablin, we induced polyploid hairy roots and their plant regeneration, and determined the content of patchouli alcohol through artificial chromosome doubling with colchicine. The highest rate of polyploidy induction was more than 40% when hairy roots were treated with 0.05% colchicine for 36 h. The obtained polyploid hairy roots formed adventitious shoots when cultured in an MS medium with 6-BA 0.2 mg/L and NAA 0.1 mg/L for 60 d. Compared with the control diploid plants, the polyploid hairy root-regenerated plants of P. cablin had more developed root systems, thicker stems, shorter internodes and longer, wider and thicker leaves. Observation of the chromosome number in their root tip cells reveals that the obtained polyploid regenerated plants were tetraploidy, with 128 (4n = 128) chromosomes. The leaves contained around twice as many stomatal guard cells and chloroplasts as the controls, but the stomatal density declined with increasing ploidy. The stomatal density in diploid plants was around 1.67 times of that in polyploid plants. GC-MS analysis shows that the content of patchouli alcholol in the hairy root-derived polyploid plants was about 4.25 mg/g dry weight, which was 2.3 times of that in diploid plants. The present study demonstrates that polyploidization of hairy roots can stimulate the content of patchouli alcholol in medicinal plant of P. cablin. PMID:25423753

  4. Root traits contributing to plant productivity under drought

    PubMed Central

    Comas, Louise H.; Becker, Steven R.; Cruz, Von Mark V.; Byrne, Patrick F.; Dierig, David A.

    2013-01-01

    Geneticists and breeders are positioned to breed plants with root traits that improve productivity under drought. However, a better understanding of root functional traits and how traits are related to whole plant strategies to increase crop productivity under different drought conditions is needed. Root traits associated with maintaining plant productivity under drought include small fine root diameters, long specific root length, and considerable root length density, especially at depths in soil with available water. In environments with late season water deficits, small xylem diameters in targeted seminal roots save soil water deep in the soil profile for use during crop maturation and result in improved yields. Capacity for deep root growth and large xylem diameters in deep roots may also improve root acquisition of water when ample water at depth is available. Xylem pit anatomy that makes xylem less “leaky” and prone to cavitation warrants further exploration holding promise that such traits may improve plant productivity in water-limited environments without negatively impacting yield under adequate water conditions. Rapid resumption of root growth following soil rewetting may improve plant productivity under episodic drought. Genetic control of many of these traits through breeding appears feasible. Several recent reviews have covered methods for screening root traits but an appreciation for the complexity of root systems (e.g., functional differences between fine and coarse roots) needs to be paired with these methods to successfully identify relevant traits for crop improvement. Screening of root traits at early stages in plant development can proxy traits at mature stages but verification is needed on a case by case basis that traits are linked to increased crop productivity under drought. Examples in lesquerella (Physaria) and rice (Oryza) show approaches to phenotyping of root traits and current understanding of root trait genetics for breeding

  5. Understanding plant root system influences on soil strength and stability

    NASA Astrophysics Data System (ADS)

    Bengough, A. Glyn; Brown, Jennifer L.; Loades, Kenneth W.; Knappett, Jonathan A.; Meijer, Gertjan; Nicoll, Bruce

    2016-04-01

    Keywords: root growth, soil reinforcement, tensile strength Plant roots modify and reinforce the soil matrix, stabilising it against erosion and shallow landslides. Roots mechanically bind the soil particles together and modify the soil hydrology via water uptake, creation of biopores, and modification of the soil water-release characteristic. Key to understanding the mechanical reinforcement of soil by roots is the relation between root strength and root diameter measured for roots in any given soil horizon. Thin roots have frequently been measured to have a greater tensile strength than thick roots, but their strength is also often much more variable. We consider the factors influencing this strength-diameter relationship, considering relations between root tensile strength and root dry density, root water content, root age, and root turnover in several woody and non-woody species. The role of possible experimental artefacts and measurement techniques will be considered. Tensile strength increased generally with root age and decreased with thermal time after excision as a result of root decomposition. Single factors alone do not appear to explain the strength-diameter relationship, and both strength/stiffness and dry density may vary between different layers of tissue within a single root. Results will be discussed to consider how we can achieve a more comprehensive understanding of the variation in root biomechanical properties, and its consequences for soil reinforcement. Acknowledgements: The James Hutton Institute receives funding from the Scottish Government. AGB and JAK acknowledge part funding from EPSRC (EP/M020355/1).

  6. Alkamides Isolated from Plants Promote Growth and Alter Root Development in Arabidopsis1

    PubMed Central

    Ramírez-Chávez, Enrique; López-Bucio, José; Herrera-Estrella, Luis; Molina-Torres, Jorge

    2004-01-01

    To date, several classes of hormones have been described that influence plant development, including auxins, cytokinins, ethylene, and, more recently, brassinosteroids. However, it is known that many fungal and bacterial species produce substances that alter plant growth that, if naturally present in plants, might represent novel classes of plant growth regulators. Alkamides are metabolites widely distributed in plants with a broad range of biological activities. In this work, we investigated the effects of affinin, an alkamide naturally occurring in plants, and its derivates, N-isobutyl-2E-decenamide and N-isobutyl-decanamide, on plant growth and early root development in Arabidopsis. We found that treatments with affinin in the range of 10-6 to 10-4 m alter shoot and root biomass production. This effect correlated with alteration on primary root growth, lateral root formation, and root hair elongation. Low concentrations of affinin (7 × 10-6–2.8 × 10-5 m) enhanced primary root growth and root hair elongation, whereas higher concentrations inhibited primary root growth that related with a reduction in cell proliferating activity and cell elongation. N-isobutyl-2E-decenamide and N-isobutyl-decanamide were found to stimulate root hair elongation at concentrations between 10-8 to 10-7 m. Although the effects of alkamides were similar to those produced by auxins on root growth and cell parameters, the ability of the root system to respond to affinin was found to be independent of auxin signaling. Our results suggest that alkamides may represent a new group of plant growth promoting substances with significant impact on root development and opens the possibility of using these compounds for improved plant production. PMID:14988477

  7. Metabolic analysis of the increased adventitious rooting mutant of Artemisia annua reveals a role for the plant monoterpene borneol in adventitious root formation.

    PubMed

    Tian, Na; Liu, Shuoqian; Li, Juan; Xu, Wenwen; Yuan, Lin; Huang, Jianan; Liu, Zhonghua

    2014-08-01

    Adventitious root (AR) formation is a critical process for plant clonal propagation. The role of plant secondary metabolites in AR formation is still poorly understood. Chemical and physical mutagenesis in combination with somatic variation were performed on Artemisia annua in order to obtain a mutant with changes in adventitious rooting and composition of plant secondary metabolites. Metabolic and morphological analyses of the iar (increased adventitious rooting) mutant coupled with in vitro assays were used to elucidate the relationship between plant secondary metabolites and AR formation. The only detected differences between the iar mutant and wild-type were rooting capacity and borneol/camphor content. Consistent with this, treatment with borneol in vitro promoted adventitious rooting in wild-type. The enhanced rooting did not continue upon removal of borneol. The iar mutant displayed no significant differences in AR formation upon treatment with camphor. Together, our results suggest that borneol promotes adventitious rooting whereas camphor has no effect on AR formation. PMID:24329606

  8. Root lengths of plants on Los Alamos National Laboratory lands

    SciTech Connect

    Tierney, G.D.; Foxx, T.S.

    1987-01-01

    Maximum root lengths of 22 plant species occurring on Los Alamos National Laboratory lands were measured. An average of two longest roots from each species were dug up and their lengths, typical shapes, and qualitative morphologics were noted along with the overstory dimensions of the plant individual with which the roots were associated. Maximum root lengths were compared with overstory (height times width) dimensions. Among the life forms studied, the shrubs tend to show the longest roots in relation to overstory size. Forbs show the shortest roots in relation to overstory size. Measurements of tree roots suggest only that immature trees on the Pajarito Plateau may have root-length to overstory-size ratios near one. 30 refs., 14 figs., 2 tabs.

  9. Plant root absorption and metabolic fate of technetium in plants

    SciTech Connect

    Cataldo, D.A.; Garland, T.R.; Wildung, R.E.

    1984-10-01

    Root absorption characteristics for the pertechnetate ion (TcO/sub 4//sup -/) were determined using hydroponically grown soybean seedlings (Glycine max, cv. Williams). Absorption of TcO/sub 4//sup -/ was found to be linear with time, sensitive to metabolic inhibitors, and exhibit multiple absorption isotherms over the concentration range 0.02 to 10 ..mu..M. The isotherms had calculated K/sub s/ values of 0.09, 8.9, and 54 ..mu..M for intact seedlings. The uptake of TcO/sub 4//sup -/ (0.25 ..mu..M) was inhibited by a fourfold concentration excess of sulfate, phosphate, and selenate, but not by borate, nitrate, tungstate, perrhenate, iodate or vanadate. Kinetic studies demonstrated that sulfate, phosphate, and selenate were competitive inhibitors of TcO/sub 4//sup -/ absorption. Once absorbed, Tc was readily transported as TcO/sub 4//sup -/ to shoot tissues of soybean and subsequently associated with protein constituents. The chemical fate of Tc in plants varies with plant species. Plants high in nonprotein sulfhydryl compounds (Allium species) exhibited markedly different root/shoot distribution and protein incorporation patterns from species with low sulfur requirements (soybean, alfalfa, mustard). Based on these differences, Tc/S/Se tracer studies were employed to resolve the comparative fate of these probable analogs. 20 references, 5 figures, 5 tables.

  10. Transformation of the Herbicide Sulcotrione into a Root Growth Enhancer Compound by Sequential Photolysis and Hydrolysis.

    PubMed

    Goujon, Eric; Maruel, Sandra; Richard, Claire; Goupil, Pascale; Ledoigt, Gérard

    2016-01-27

    Xanthene-1,9-dione-3,4-dihydro-6-methylsulfonyl (1), the main product of sulcotrione phototransformation on plant leaves, was slowly hydrolyzed into 2-hydroxy-4-methylsulfonylbenzoic acid (2) and 1,3-cyclohexanedione (3) in aqueous solution. Interestingly, the rate of hydrolysis was significantly enhanced in the presence of roots of monocotyledonous plants, while the same treatment showed adverse effects on broadleaf weeds. Root growth enhancement varied according to the plant species and concentrations of compound 2, as shown with Zea mays roots. Compound 2 is a derivative of salicylic acid that is known to be a plant signaling messenger. Compound 2 was, therefore, able to mimic some known effects of this phytohormone. This work showed that a pesticide like sulcotrione was transformed into a compound exhibiting a positive impact on plant growth. This study exemplified a rarely reported situation where chemical and biological chain reactions transformed a xenobiotic into a compound exhibiting potential beneficial effects. PMID:26654319

  11. Scaling root processes based on plant functional traits (Invited)

    NASA Astrophysics Data System (ADS)

    Eissenstat, D. M.; McCormack, M. L.; Gaines, K.; Adams, T.

    2013-12-01

    There are great challenges to scaling root processes as variation across species and variation of a particular species over different spatial and temporal scales is poorly understood. We have examined tree species variation using multispecies plantings, often referred to by ecologists as 'common gardens'. Choosing species with wide variation in growth rate, root morphology (diameter, branching intensity) and root chemistry (root N and Ca concentration), we found that variation in root lifespan was well correlated with plant functional traits across 12 species. There was also evidence that localized liquid N addition could increase root lifespan and localized water addition diminished root lifespan over untreated controls, with effects strongest in the species of finest root diameter. In an adjacent forest, we have also seen tree species variation in apparent depth of rooting using water isotopes. In particular species of wood anatomy that was ring porous (e.g. oaks) typically had the deepest rooting depth, whereas those that had either diffuse-porous sapwood (maples) or tracheid sapwood (pines) were shallower rooted. These differences in rooting depth were related to sap flux of trees during and immediately after periods of drought. The extent that the patterns observed in central Pennsylvania are modulated by environment or indicative of other plant species will be discussed.

  12. Dig Alfalfa Plants to Assess Root Rots and Yield Potential

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Digging alfalfa plants and inspecting their crowns and roots for rot is critical to assess stand health and production potential. Brown root rot (BRR) has been a significant plant disease on alfalfa for decades but until recently was thought to only cause significant damage in western Canada. With i...

  13. Root traits contributing to plant productivity under drought

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Geneticists and breeders are poised to breed plants with root traits that improve productivity under drought. However, they need a better understanding of root functional traits and how these traits are related to whole plant strategies to increase crop productivity under different drought conditio...

  14. Root-Specific Reduction of Cytokinin Causes Enhanced Root Growth, Drought Tolerance, and Leaf Mineral Enrichment in Arabidopsis and Tobacco[C][W][OA

    PubMed Central

    Werner, Tomáš; Nehnevajova, Erika; Köllmer, Ireen; Novák, Ondřej; Strnad, Miroslav; Krämer, Ute; Schmülling, Thomas

    2010-01-01

    Optimizing root system architecture can overcome yield limitations in crop plants caused by water or nutrient shortages. Classic breeding approaches are difficult because the trait is governed by many genes and is difficult to score. We generated transgenic Arabidopsis thaliana and tobacco (Nicotiana tabacum) plants with enhanced root-specific degradation of the hormone cytokinin, a negative regulator of root growth. These transgenic plants form a larger root system, whereas growth and development of the shoot are similar. Elongation of the primary root, root branching, and root biomass formation were increased by up to 60% in transgenic lines, increasing the root-to-shoot ratio. We thus demonstrated that a single dominant gene could regulate a complex trait, root growth. Moreover, we showed that cytokinin regulates root growth in a largely organ-autonomous fashion that is consistent with its dual role as a hormone with both paracrine and long-distance activities. Transgenic plants had a higher survival rate after severe drought treatment. The accumulation of several elements, including S, P, Mn, Mg, Zn, as well as Cd from a contaminated soil, was significantly increased in shoots. Under conditions of sulfur or magnesium deficiency, leaf chlorophyll content was less affected in transgenic plants, demonstrating the physiological relevance of shoot element accumulation. Our approach might contribute to improve drought tolerance, nutrient efficiency, and nutrient content of crop plants. PMID:21148816

  15. Transgenic plants and hairy roots: exploiting the potential of plant species to remediate contaminants.

    PubMed

    Ibañez, Sabrina; Talano, Melina; Ontañon, Ornella; Suman, Jachym; Medina, María I; Macek, Tomas; Agostini, Elizabeth

    2016-09-25

    Phytoremediation has emerged as an attractive methodology to deal with environmental pollution, which is a serious worldwide problem. Although important advances have been made in this research field, there are still some drawbacks to become a widely used practice, such as the limited plant's metabolic rate and their difficulty to break down several organic compounds or to tolerate/accumulate heavy metals. However, biotechnology has opened new gateways in phytoremediation research by offering the opportunity for direct gene transfer to enhance plant capabilities for environmental cleanup. In this context, hairy roots (HRs) have emerged as an interesting model system to explore the potential of plants to remove inorganic and organic pollutants. Besides, their use in rhizoremediation studies has also been explored. In this minireview we will discuss the most recent advances using genetic engineering for enhancing phytoremediation capabilities of plants and HRs. PMID:26703807

  16. Plant diversity effects on root decomposition in grasslands

    NASA Astrophysics Data System (ADS)

    Chen, Hongmei; Mommer, Liesje; van Ruijven, Jasper; de Kroon, Hans; Gessler, Arthur; Scherer-Lorenzen, Michael; Wirth, Christian; Weigelt, Alexandra

    2016-04-01

    Loss of plant diversity impairs ecosystem functioning. Compared to other well-studied processes, we know little about whether and how plant diversity affects root decomposition, which is limiting our knowledge on biodiversity-carbon cycling relationships in the soil. Plant diversity potentially affects root decomposition via two non-exclusive mechanisms: by providing roots of different substrate quality and/or by altering the soil decomposition environment. To disentangle these two mechanisms, three decomposition experiments using a litter-bag approach were conducted on experimental grassland plots differing in plant species richness, functional group richness and functional group composition (e.g. presence/absence of grasses, legumes, small herbs and tall herbs, the Jena Experiment). We studied: 1) root substrate quality effects by decomposing roots collected from the different experimental plant communities in one common plot; 2) soil decomposition environment effects by decomposing standard roots in all experimental plots; and 3) the overall plant diversity effects by decomposing community roots in their 'home' plots. Litter bags were installed in April 2014 and retrieved after 1, 2 and 4 months to determine the mass loss. We found that mass loss decreased with increasing plant species richness, but not with functional group richness in the three experiments. However, functional group presence significantly affected mass loss with primarily negative effects of the presence of grasses and positive effects of the presence of legumes and small herbs. Our results thus provide clear evidence that species richness has a strong negative effect on root decomposition via effects on both root substrate quality and soil decomposition environment. This negative plant diversity-root decomposition relationship may partly account for the positive effect of plant diversity on soil C stocks by reducing C loss in addition to increasing primary root productivity. However, to fully

  17. Enhancing Students' Understanding of Square Roots

    ERIC Educational Resources Information Center

    Wiesman, Jeff L.

    2015-01-01

    Students enrolled in a middle school prealgebra or algebra course often struggle to conceptualize and understand the meaning of radical notation when it is introduced. For example, although it is important for students to approximate the decimal value of a number such as [square root of] 30 and estimate the value of a square root in the form of…

  18. Plant development in space: Observations on root formation and growth

    NASA Technical Reports Server (NTRS)

    Levine, H. G.; Kann, R. P.; Krikorian, Abraham D.

    1990-01-01

    Root growth in space is discussed and observations on root production from plants flown as part of the Chromex project that were defined as to their origin, stage of development and physiological status, are presented. Roots were generated from fully differentiated, aseptically maintained individuals of Haplopappus gracilis (Compositae) under spaceflight conditions. Results are compared for tissue culture generated plantlets and comparably sized seedling clone individuals, both of which had their roots trimmed on Earth before they were loaded into NASA's plant growth unit and subjected to a 5 day shuttle flight (STS-29). Asepsis was maintained throughout the experiment. Overall root production was 40 to 50 percent greater under spaceflight conditions than during ground control tests. However, root formation slowed down towards the end of the flight. This decrease in new roots did not occur in the ground controls that sought to simulate flight except for microgravity.

  19. UPTAKE OF BACTERIOPHAGE F2 THROUGH PLANT ROOTS

    EPA Science Inventory

    A model system was designed to measure viral uptake through the roots of plants and translocation to distal plant parts. For this study, uptake of bacteriophage f2 was measured in corn and bean plants growing in hydroponic solutions. Few phage were detected in plants with uncut r...

  20. A chamber for applying pressure to roots of intact plants.

    PubMed

    Gee, G W

    1973-11-01

    A chamber was designed to apply up to 20 bars pressure to roots of intact plants. The unique features of this chamber are a split top arrangement to permit enclosing roots of intact plants within the chamber, a circulation coil to control temperature of rooting media, and a valve arrangement to permit changing solution without disturbing the plant. Changes in transpiration in response to changes in the pressure applied to roots of intact pepper plants illustrate one use of the equipment. Well watered plants at low light (0.05 langley/min) were observed to exude water from the leaf margins when 5 bars pressure was applied to the roots. When roots were cut off, a 1 bar pressure caused exudation. Plants with cooled roots or plants in dry soil did not exude water when as much as 6 bars pressure was applied. Transient response of transpiration rates to sudden application and release of pressure was observed in pepper and bean plants but not in rhododendron. The magnitude of this transient response was highly dependent upon light intensity and CO(2) concentration in the aerial environment. PMID:16658586

  1. Side-Branching Statistics of Plant Root Networks

    NASA Astrophysics Data System (ADS)

    Pollen, N.; Malamud, B.

    2001-12-01

    Many studies exist that characterise plant root architecture by calculating the fractal dimension of the root network, but few studies quantify the branching characteristics of the root network. This paper examines the Tokunaga side-branching statistics for the root systems of four plants--Sugar Beet (Beta vulgaris), Lucern (Medicago sativa), Common Wheat (Triticum aestivum) and White Clover (Trifolium michelianum)--and compares the resulting statistics to those calculated by similar means (by other authors) for the Kentucky and Powder River drainage basins and several Diffusion Limited Aggregation (DLA) models. The plant root networks studied all contained similar numbers of different order roots, but the side-branching statistics differed, offering one explanation for the differing visual appearance of the branching root networks. The White Clover plant had similar Tokunaga branching statistics to the drainage networks and DLA models. This may be due to the dichotomous root structure of the White Clover plant, which produces a network that is much more similar in appearance to the two drainage networks and DLA models than the other three plants, which had herringbone root. All of the root networks, drainage basins, and DLA models had branching networks that could be quantified well to very well by Tokunaga side-branching statistics. For many years, engineers have avoided implementation of stabilisation schemes involving vegetation, due to the inherent problems involved in the quantification of their dynamic and complex root structures. The use of Tokunaga statistics as a simplifying measure of root branching characteristics, may aid in this aspect, as well as others, such as the modelling of nutrient or water uptake.

  2. Root Border Cells and Their Role in Plant Defense.

    PubMed

    Hawes, Martha; Allen, Caitilyn; Turgeon, B Gillian; Curlango-Rivera, Gilberto; Minh Tran, Tuan; Huskey, David A; Xiong, Zhongguo

    2016-08-01

    Root border cells separate from plant root tips and disperse into the soil environment. In most species, each root tip can produce thousands of metabolically active cells daily, with specialized patterns of gene expression. Their function has been an enduring mystery. Recent studies suggest that border cells operate in a manner similar to mammalian neutrophils: Both cell types export a complex of extracellular DNA (exDNA) and antimicrobial proteins that neutralize threats by trapping pathogens and thereby preventing invasion of host tissues. Extracellular DNases (exDNases) of pathogens promote virulence and systemic spread of the microbes. In plants, adding DNase I to root tips eliminates border cell extracellular traps and abolishes root tip resistance to infection. Mutation of genes encoding exDNase activity in plant-pathogenic bacteria (Ralstonia solanacearum) and fungi (Cochliobolus heterostrophus) results in reduced virulence. The study of exDNase activities in plant pathogens may yield new targets for disease control. PMID:27215971

  3. A comparative study on the potential of oxygen release by roots of selected wetland plants

    NASA Astrophysics Data System (ADS)

    Yao, Fang; Shen, Gen-xiang; Li, Xue-lian; Li, Huai-zheng; Hu, Hong; Ni, Wu-zhong

    The capacity of root oxygen release by selected wetland plants pre-grown under both nutrient solution and artificial wastewater conditions were determined. The results indicated that the significant differences of root oxygen release by the tested wetland plants existed, and the biochemical process was the main source of root oxygen release as oxygen released by Vetiveria zizanioides L. Nash roots through biochemical process was contributed to 77% and 74% of total root oxygen release under nutrient solution conditions and artificial wastewater conditions, respectively, and that was 72% and 71% of total root oxygen release for Cyperus alternifolius L. It was found that the formation of root plaque with iron oxide was a function of root oxygen release as iron oxide concentration in root plaque was positively correlated to the potential of oxygen released by wetland plant roots with the regression coefficients as 0.874 *( p < 0.05) under nutrient solution conditions and 0.944 **( p < 0.01) under artificial wastewater conditions, which could be regarded as an important mechanism of wetland plants being tolerant to anoxia during wastewater treatment. It was suggested that the potential of root oxygen release could be used as a parameter for selecting wetland plants that can increase oxygen supply to soil or substrate of constructed wetlands and enhance nutrient transformation and removal, and V. zizanioides L. Nash with the highest potential of root oxygen release and higher tolerance to wastewater could be recommended to establish vegetated wetlands for treating nutrient-rich wastewater such as domestic wastewater.

  4. Modelling increased soil cohesion by plant roots with EUROSEM

    NASA Astrophysics Data System (ADS)

    de Baets, S.; Poesen, J.; Torri, D.; Salvador, M. P.

    2009-04-01

    Soil cohesion is an important variable to model soil detachment by runoff (Morgan et al., 1998a). As soil particles are not loose, soil detachment by runoff will be limited by the cohesion of the soil material. It is generally recognized that plant roots contribute to the overall cohesion of the soil. Determination of this increased cohesion and soil roughness however is complicated and measurements of shear strength and soil reinforcement by plant roots are very time- and labour consuming. A model approach offers an alternative for the assessment of soil cohesion provided by plant roots However, few erosion models account for the effects of the below-ground biomass in their calculation of erosion rates. Therefore, the main objectives of this study is to develop an approach to improve an existing soil erosion model (EUROSEM) accounting for the erosion-reducing effects of roots. The approach for incorporating the root effects into this model is based on a comparison of measured soil detachment rates for bare and for root-permeated topsoil samples with predicted erosion rates under the same flow conditions using the erosion equation of EUROSEM. Through backwards calculation, transport capacity efficiencies and corresponding soil cohesion values can be assessed for bare and root-permeated topsoils respectively. The results are promising and show that grass roots provide a larger increase in soil cohesion as compared with tap-rooted species and that the increase in soil cohesion is not significantly different under wet and dry soil conditions, either for fibrous root systems or for tap root systems. Relationships are established between measured root density values and the corresponding calculated soil cohesion values, reflecting the effects of roots on the resistance of the topsoil to concentrated flow incision. These relationships enable one to incorporate the root effect into the soil erosion model EUROSEM, through adapting the soil cohesion input value. A scenario

  5. Role of calcium in gravity perception of plant roots

    NASA Astrophysics Data System (ADS)

    Evans, Michael L.

    Calcium ions may play a key role in linking graviperception by the root cap to the asymmetric growth which occurs in the elongation zone of gravistimulated roots. Application of calcium-chelating agents to the root cap inhibits gravitropic curvature without affecting growth. Asymmetric application of calcium to one side of the root cap induces curvature toward the calcium source, and gravistimulation induces polar movement of applied 45Ca2+ across the root cap toward the lower side. The action of calcium may be linked to auxin movement in roots since 1) auxin transport inhibitors interfere both with gravitropic curvature and gravi-induced polar calcium movement and 2) asymmetric application of calcium enhances auxin movement across the elongation zone of gravistimulated roots. Indirect evidence indicates that the calcium-modulated regulator protein, calmodulin, may be involved in either the transport or action of calcium in the gravitropic response mechanism of roots.

  6. Root foraging influences plant growth responses to earthworm foraging.

    PubMed

    Cameron, Erin K; Cahill, James F; Bayne, Erin M

    2014-01-01

    Interactions among the foraging behaviours of co-occurring animal species can impact population and community dynamics; the consequences of interactions between plant and animal foraging behaviours have received less attention. In North American forests, invasions by European earthworms have led to substantial changes in plant community composition. Changes in leaf litter have been identified as a critical indirect mechanism driving earthworm impacts on plants. However, there has been limited examination of the direct effects of earthworm burrowing on plant growth. Here we show a novel second pathway exists, whereby earthworms (Lumbricus terrestris L.) impact plant root foraging. In a mini-rhizotron experiment, roots occurred more frequently in burrows and soil cracks than in the soil matrix. The roots of Achillea millefolium L. preferentially occupied earthworm burrows, where nutrient availability was presumably higher than in cracks due to earthworm excreta. In contrast, the roots of Campanula rotundifolia L. were less likely to occur in burrows. This shift in root behaviour was associated with a 30% decline in the overall biomass of C. rotundifolia when earthworms were present. Our results indicate earthworm impacts on plant foraging can occur indirectly via physical and chemical changes to the soil and directly via root consumption or abrasion and thus may be one factor influencing plant growth and community change following earthworm invasion. More generally, this work demonstrates the potential for interactions to occur between the foraging behaviours of plants and soil animals and emphasizes the importance of integrating behavioural understanding in foraging studies involving plants. PMID:25268503

  7. Root Foraging Influences Plant Growth Responses to Earthworm Foraging

    PubMed Central

    Cameron, Erin K.; Cahill, James F.; Bayne, Erin M.

    2014-01-01

    Interactions among the foraging behaviours of co-occurring animal species can impact population and community dynamics; the consequences of interactions between plant and animal foraging behaviours have received less attention. In North American forests, invasions by European earthworms have led to substantial changes in plant community composition. Changes in leaf litter have been identified as a critical indirect mechanism driving earthworm impacts on plants. However, there has been limited examination of the direct effects of earthworm burrowing on plant growth. Here we show a novel second pathway exists, whereby earthworms (Lumbricus terrestris L.) impact plant root foraging. In a mini-rhizotron experiment, roots occurred more frequently in burrows and soil cracks than in the soil matrix. The roots of Achillea millefolium L. preferentially occupied earthworm burrows, where nutrient availability was presumably higher than in cracks due to earthworm excreta. In contrast, the roots of Campanula rotundifolia L. were less likely to occur in burrows. This shift in root behaviour was associated with a 30% decline in the overall biomass of C. rotundifolia when earthworms were present. Our results indicate earthworm impacts on plant foraging can occur indirectly via physical and chemical changes to the soil and directly via root consumption or abrasion and thus may be one factor influencing plant growth and community change following earthworm invasion. More generally, this work demonstrates the potential for interactions to occur between the foraging behaviours of plants and soil animals and emphasizes the importance of integrating behavioural understanding in foraging studies involving plants. PMID:25268503

  8. The unseen iceberg: Plant roots in arctic tundra

    DOE PAGESBeta

    Iversen, Colleen M; Sloan, Victoria L; Sullivan, Patrick F.; Euskirchen, Eugenie S; McGuire, A. David; Norby, Richard J; Walker, Anthony P; Warren, Jeffrey; Wullschleger, Stan D

    2015-01-01

    Arctic tundra is characterized by short-statured plant communities underlain by carbon (C)-rich soils and permafrost. Ecosystem C and nutrient cycles in tundra are driven by complex interactions between plants and their environment. However, root dynamics are one of the least understood aspects of plant growth in the Arctic. We synthesized available literature on tundra roots and discussed their representation in terrestrial biosphere models. Belowground biomass in tundra ecosystems can be an order of magnitude larger than aboveground biomass. Data on root production and turnover in tundra is sparse, limiting our understanding of the controls over root dynamics in these systems.more » Roots are shallowly distributed in the thin layer of soil that thaws each year, and are often found in the organic horizon at the soil surface. Species-specific differences in root distribution, mycorrhizal colonization, and resource partitioning may affect plant species competition under changing climatic conditions. Model representation of belowground processes has increased in complexity over recent years, but data are desperately needed to fill the gaps in model treatment of tundra roots. Future research should focus on estimates of root production and lifespan, and interactions between roots and the surrounding soil across the diversity of tundra ecosystems in the Arctic.« less

  9. The unseen iceberg: Plant roots in arctic tundra

    SciTech Connect

    Iversen, Colleen M; Sloan, Victoria L; Sullivan, Patrick F.; Euskirchen, Eugenie S; McGuire, A. David; Norby, Richard J; Walker, Anthony P; Warren, Jeffrey; Wullschleger, Stan D

    2015-01-01

    Arctic tundra is characterized by short-statured plant communities underlain by carbon (C)-rich soils and permafrost. Ecosystem C and nutrient cycles in tundra are driven by complex interactions between plants and their environment. However, root dynamics are one of the least understood aspects of plant growth in the Arctic. We synthesized available literature on tundra roots and discussed their representation in terrestrial biosphere models. Belowground biomass in tundra ecosystems can be an order of magnitude larger than aboveground biomass. Data on root production and turnover in tundra is sparse, limiting our understanding of the controls over root dynamics in these systems. Roots are shallowly distributed in the thin layer of soil that thaws each year, and are often found in the organic horizon at the soil surface. Species-specific differences in root distribution, mycorrhizal colonization, and resource partitioning may affect plant species competition under changing climatic conditions. Model representation of belowground processes has increased in complexity over recent years, but data are desperately needed to fill the gaps in model treatment of tundra roots. Future research should focus on estimates of root production and lifespan, and interactions between roots and the surrounding soil across the diversity of tundra ecosystems in the Arctic.

  10. The signature of randomness in riparian plant root distributions

    NASA Astrophysics Data System (ADS)

    Tron, Stefania; Perona, Paolo; Gorla, Lorenzo; Schwarz, Massimiliano; Laio, Francesco; Ridolfi, Luca

    2015-09-01

    Known as "the hidden half", plant roots are fundamental contributors to the riparian ecosystem functioning. Roots show an extraordinary architectural complexity that recalls their remarkable ability to adapt to environmental heterogeneity, resources availability, and climate. In fluvial environments, phreatophytes and hydrophytes cope with flow and sediment processes, and hydrotropism and aerotropism are the main drivers for root growth. In this work, we show how the vertical root density distribution in riparian plants is the result of how plants respond to the random fluctuations of river flows. A root data set from field and controlled outdoor experiments is used in combination with a physically based analytical model to demonstrate that the root vertical density distribution can be ascribed to the interplay of randomness and determinism in a simple mathematical form. The shape of the distribution reflects the profitability of plant roots to grow in different soil layers depending on the soil moisture availability. For the first time, this model helps understanding in an analytical manner the adaptation strategy of plant roots to different scenarios, paving the way for the comprehension of the effects of future changes in climate and environmental conditions.

  11. Use of plant roots for phytoremediation and molecular farming

    PubMed Central

    Gleba, Doloressa; Borisjuk, Nikolai V.; Borisjuk, Ludmyla G.; Kneer, Ralf; Poulev, Alexander; Skarzhinskaya, Marina; Dushenkov, Slavik; Logendra, Sithes; Gleba, Yuri Y.; Raskin, Ilya

    1999-01-01

    Alternative agriculture, which expands the uses of plants well beyond food and fiber, is beginning to change plant biology. Two plant-based biotechnologies were recently developed that take advantage of the ability of plant roots to absorb or secrete various substances. They are (i) phytoextraction, the use of plants to remove pollutants from the environment and (ii) rhizosecretion, a subset of molecular farming, designed to produce and secrete valuable natural products and recombinant proteins from roots. Here we discuss recent advances in these technologies and assess their potential in soil remediation, drug discovery, and molecular farming. PMID:10339526

  12. Silicon modifies root anatomy, and uptake and subcellular distribution of cadmium in young maize plants

    PubMed Central

    Vaculík, Marek; Landberg, Tommy; Greger, Maria; Luxová, Miroslava; Stoláriková, Miroslava; Lux, Alexander

    2012-01-01

    Background and Aims Silicon (Si) has been shown to ameliorate the negative influence of cadmium (Cd) on plant growth and development. However, the mechanism of this phenomenon is not fully understood. Here we describe the effect of Si on growth, and uptake and subcellular distribution of Cd in maize plants in relation to the development of root tissues. Methods Young maize plants (Zea mays) were cultivated for 10 d hydroponically with 5 or 50 µm Cd and/or 5 mm Si. Growth parameters and the concentrations of Cd and Si were determined in root and shoot by atomic absorption spectrometry or inductively coupled plasma mass spectroscopy. The development of apoplasmic barriers (Casparian bands and suberin lamellae) and vascular tissues in roots were analysed, and the influence of Si on apoplasmic and symplasmic distribution of 109Cd applied at 34 nm was investigated between root and shoot. Key Results Si stimulated the growth of young maize plants exposed to Cd and influenced the development of Casparian bands and suberin lamellae as well as vascular tissues in root. Si did not affect the distribution of apoplasmic and symplasmic Cd in maize roots, but considerably decreased symplasmic and increased apoplasmic concentration of Cd in maize shoots. Conclusions Differences in Cd uptake of roots and shoots are probably related to the development of apoplasmic barriers and maturation of vascular tissues in roots. Alleviation of Cd toxicity by Si might be attributed to enhanced binding of Cd to the apoplasmic fraction in maize shoots. PMID:22455991

  13. Root cause analysis at the Savannah River Plant

    SciTech Connect

    Paradies, M; Busch, D

    1988-01-01

    Events (or near misses) provide important information about ways to improve plant performance. Any particular event may have several /open quotes/root causes/close quotes/ that need correcting to prevent recurrence of the event and, thereby, improve the safety of the plant. Also, by reviewing a large number of events, one can identify cause trends or /open quotes/generic concerns./close quotes/ A method has been developed at Savannah River Plant (SRP) to systematically evaluate events, identify their root causes, record the root causes, and analyze the root cause trends. By providing a systematic method to identify correctable root causes, the system helps the event investigator ask the right questions during the investigation. It also provides an independent safety analysis group and management with statistics indicating existing and developing trouble spots. 3 refs., 4 figs.

  14. The symbiosis with the arbuscular mycorrhizal fungus Rhizophagus irregularis drives root water transport in flooded tomato plants.

    PubMed

    Calvo-Polanco, Monica; Molina, Sonia; Zamarreño, Angel María; García-Mina, Jose María; Aroca, Ricardo

    2014-05-01

    It is known that the presence of arbuscular mycorrhizal fungi within the plant roots enhances the tolerance of the host plant to different environmental stresses, although the positive effect of the fungi in plants under waterlogged conditions has not been well studied. Tolerance of plants to flooding can be achieved through different molecular, physiological and anatomical adaptations, which will affect their water uptake capacity and therefore their root hydraulic properties. Here, we investigated the root hydraulic properties under non-flooded and flooded conditions in non-mycorrhizal tomato plants and plants inoculated with the arbuscular mycorrhizal fungus Rhizophagus irregularis. Only flooded mycorrhizal plants increased their root hydraulic conductivity, and this effect was correlated with a higher expression of the plant aquaporin SlPIP1;7 and the fungal aquaporin GintAQP1. There was also a higher abundance of the PIP2 protein phoshorylated at Ser280 in mycorrhizal flooded plants. The role of plant hormones (ethylene, ABA and IAA) in root hydraulic properties was also taken into consideration, and it was concluded that, in mycorrhizal flooded plants, ethylene has a secondary role regulating root hydraulic conductivity whereas IAA may be the key hormone that allows the enhancement of root hydraulic conductivity in mycorrhizal plants under low oxygen conditions. PMID:24553847

  15. GiA Roots: software for the high throughput analysis of plant root system architecture

    PubMed Central

    2012-01-01

    Background Characterizing root system architecture (RSA) is essential to understanding the development and function of vascular plants. Identifying RSA-associated genes also represents an underexplored opportunity for crop improvement. Software tools are needed to accelerate the pace at which quantitative traits of RSA are estimated from images of root networks. Results We have developed GiA Roots (General Image Analysis of Roots), a semi-automated software tool designed specifically for the high-throughput analysis of root system images. GiA Roots includes user-assisted algorithms to distinguish root from background and a fully automated pipeline that extracts dozens of root system phenotypes. Quantitative information on each phenotype, along with intermediate steps for full reproducibility, is returned to the end-user for downstream analysis. GiA Roots has a GUI front end and a command-line interface for interweaving the software into large-scale workflows. GiA Roots can also be extended to estimate novel phenotypes specified by the end-user. Conclusions We demonstrate the use of GiA Roots on a set of 2393 images of rice roots representing 12 genotypes from the species Oryza sativa. We validate trait measurements against prior analyses of this image set that demonstrated that RSA traits are likely heritable and associated with genotypic differences. Moreover, we demonstrate that GiA Roots is extensible and an end-user can add functionality so that GiA Roots can estimate novel RSA traits. In summary, we show that the software can function as an efficient tool as part of a workflow to move from large numbers of root images to downstream analysis. PMID:22834569

  16. RootGraph: a graphic optimization tool for automated image analysis of plant roots

    PubMed Central

    Cai, Jinhai; Zeng, Zhanghui; Connor, Jason N.; Huang, Chun Yuan; Melino, Vanessa; Kumar, Pankaj; Miklavcic, Stanley J.

    2015-01-01

    This paper outlines a numerical scheme for accurate, detailed, and high-throughput image analysis of plant roots. In contrast to existing root image analysis tools that focus on root system-average traits, a novel, fully automated and robust approach for the detailed characterization of root traits, based on a graph optimization process is presented. The scheme, firstly, distinguishes primary roots from lateral roots and, secondly, quantifies a broad spectrum of root traits for each identified primary and lateral root. Thirdly, it associates lateral roots and their properties with the specific primary root from which the laterals emerge. The performance of this approach was evaluated through comparisons with other automated and semi-automated software solutions as well as against results based on manual measurements. The comparisons and subsequent application of the algorithm to an array of experimental data demonstrate that this method outperforms existing methods in terms of accuracy, robustness, and the ability to process root images under high-throughput conditions. PMID:26224880

  17. The unseen iceberg: Plant roots in arctic tundra

    USGS Publications Warehouse

    Iverson, Colleen M.; Sloan, Victoria L.; Sullivan, Patrick F.; Euskirchen, E.S.; McGuire, Anthony; Norby, Richard J.; Walker, Anthony P.; Warren, Jeffrey M.; Wullschleger, Stan D.

    2015-01-01

    Plant roots play a critical role in ecosystem function in arctic tundra, but root dynamics in these ecosystems are poorly understood. To address this knowledge gap, we synthesized available literature on tundra roots, including their distribution, dynamics and contribution to ecosystem carbon and nutrient fluxes, and highlighted key aspects of their representation in terrestrial biosphere models. Across all tundra ecosystems, belowground plant biomass exceeded aboveground biomass, with the exception of polar desert tundra. Roots were shallowly distributed in the thin layer of soil that thaws annually, and were often found in surface organic soil horizons. Root traits – including distribution, chemistry, anatomy and resource partitioning – play an important role in controlling plant species competition, and therefore ecosystem carbon and nutrient fluxes, under changing climatic conditions, but have only been quantified for a small fraction of tundra plants. Further, the annual production and mortality of fine roots are key components of ecosystem processes in tundra, but extant data are sparse. Tundra root traits and dynamics should be the focus of future research efforts. Better representation of the dynamics and characteristics of tundra roots will improve the utility of models for the evaluation of the responses of tundra ecosystems to changing environmental conditions.

  18. Genetic improvement for root growth angle to enhance crop production.

    PubMed

    Uga, Yusaku; Kitomi, Yuka; Ishikawa, Satoru; Yano, Masahiro

    2015-03-01

    The root system is an essential organ for taking up water and nutrients and anchoring shoots to the ground. On the other hand, the root system has rarely been regarded as breeding target, possibly because it is more laborious and time-consuming to evaluate roots (which require excavation) in a large number of plants than aboveground tissues. The root growth angle (RGA), which determines the direction of root elongation in the soil, affects the area in which roots capture water and nutrients. In this review, we describe the significance of RGA as a potential trait to improve crop production, and the physiological and molecular mechanisms that regulate RGA. We discuss the prospects for breeding to improve RGA based on current knowledge of quantitative trait loci for RGA in rice. PMID:26069440

  19. Genetic improvement for root growth angle to enhance crop production

    PubMed Central

    Uga, Yusaku; Kitomi, Yuka; Ishikawa, Satoru; Yano, Masahiro

    2015-01-01

    The root system is an essential organ for taking up water and nutrients and anchoring shoots to the ground. On the other hand, the root system has rarely been regarded as breeding target, possibly because it is more laborious and time-consuming to evaluate roots (which require excavation) in a large number of plants than aboveground tissues. The root growth angle (RGA), which determines the direction of root elongation in the soil, affects the area in which roots capture water and nutrients. In this review, we describe the significance of RGA as a potential trait to improve crop production, and the physiological and molecular mechanisms that regulate RGA. We discuss the prospects for breeding to improve RGA based on current knowledge of quantitative trait loci for RGA in rice. PMID:26069440

  20. Strigolactones as Germination Stimulants for Root Parasitic Plants

    PubMed Central

    Yoneyama, Koichi; Awad, Ayman A.; Xie, Xiaonan; Yoneyama, Kaori; Takeuchi, Yasutomo

    2010-01-01

    Witchweeds (Striga spp.) and broomrapes (Orobanche and Phelipanche spp.) are the two most devastating root parasitic plants belonging to the family Orobanchaceae and are causing enormous crop losses throughout the world. Seeds of these root parasites will not germinate unless they are exposed to chemical stimuli, ‘germination stimulants’ produced by and released from plant roots. Most of the germination stimulants identified so far are strigolactones (SLs), which also function as host recognition signals for arbuscular mycorrhizal fungi and a novel class of plant hormones inhibiting shoot branching. In this review, we focus on SLs as germination stimulants for root parasitic plants. In addition, we discuss how quantitative and qualitative differences in SL exudation among sorghum cultivars influence their susceptibility to Striga. PMID:20403809

  1. Strigolactones as germination stimulants for root parasitic plants.

    PubMed

    Yoneyama, Koichi; Awad, Ayman A; Xie, Xiaonan; Yoneyama, Kaori; Takeuchi, Yasutomo

    2010-07-01

    Witchweeds (Striga spp.) and broomrapes (Orobanche and Phelipanche spp.) are the two most devastating root parasitic plants belonging to the family Orobanchaceae and are causing enormous crop losses throughout the world. Seeds of these root parasites will not germinate unless they are exposed to chemical stimuli, 'germination stimulants' produced by and released from plant roots. Most of the germination stimulants identified so far are strigolactones (SLs), which also function as host recognition signals for arbuscular mycorrhizal fungi and a novel class of plant hormones inhibiting shoot branching. In this review, we focus on SLs as germination stimulants for root parasitic plants. In addition, we discuss how quantitative and qualitative differences in SL exudation among sorghum cultivars influence their susceptibility to Striga. PMID:20403809

  2. Network modules and hubs in plant-root fungal biomes.

    PubMed

    Toju, Hirokazu; Yamamoto, Satoshi; Tanabe, Akifumi S; Hayakawa, Takashi; Ishii, Hiroshi S

    2016-03-01

    Terrestrial plants host phylogenetically and functionally diverse groups of below-ground microbes, whose community structure controls plant growth/survival in both natural and agricultural ecosystems. Therefore, understanding the processes by which whole root-associated microbiomes are organized is one of the major challenges in ecology and plant science. We here report that diverse root-associated fungi can form highly compartmentalized networks of coexistence within host roots and that the structure of the fungal symbiont communities can be partitioned into semi-discrete types even within a single host plant population. Illumina sequencing of root-associated fungi in a monodominant south beech forest revealed that the network representing symbiont-symbiont co-occurrence patterns was compartmentalized into clear modules, which consisted of diverse functional groups of mycorrhizal and endophytic fungi. Consequently, terminal roots of the plant were colonized by either of the two largest fungal species sets (represented by Oidiodendron or Cenococcum). Thus, species-rich root microbiomes can have alternative community structures, as recently shown in the relationships between human gut microbiome type (i.e., 'enterotype') and host individual health. This study also shows an analytical framework for pinpointing network hubs in symbiont-symbiont networks, leading to the working hypothesis that a small number of microbial species organize the overall root-microbiome dynamics. PMID:26962029

  3. Tomato PYR/PYL/RCAR abscisic acid receptors show high expression in root, differential sensitivity to the abscisic acid agonist quinabactin, and the capability to enhance plant drought resistance

    PubMed Central

    González-Guzmán, Miguel; Rodríguez, Lesia; Lorenzo-Orts, Laura; Pons, Clara; Sarrión-Perdigones, Alejandro; Fernández, Maria A.; Peirats-Llobet, Marta; Forment, Javier; Moreno-Alvero, Maria; Cutler, Sean R.; Albert, Armando; Granell, Antonio; Rodríguez, Pedro L.

    2014-01-01

    Abscisic acid (ABA) plays a crucial role in the plant’s response to both biotic and abiotic stress. Sustainable production of food faces several key challenges, particularly the generation of new varieties with improved water use efficiency and drought tolerance. Different studies have shown the potential applications of Arabidopsis PYR/PYL/RCAR ABA receptors to enhance plant drought resistance. Consequently the functional characterization of orthologous genes in crops holds promise for agriculture. The full set of tomato (Solanum lycopersicum) PYR/PYL/RCAR ABA receptors have been identified here. From the 15 putative tomato ABA receptors, 14 of them could be grouped in three subfamilies that correlated well with corresponding Arabidopsis subfamilies. High levels of expression of PYR/PYL/RCAR genes was found in tomato root, and some genes showed predominant expression in leaf and fruit tissues. Functional characterization of tomato receptors was performed through interaction assays with Arabidopsis and tomato clade A protein phosphatase type 2Cs (PP2Cs) as well as phosphatase inhibition studies. Tomato receptors were able to inhibit the activity of clade A PP2Cs differentially in an ABA-dependent manner, and at least three receptors were sensitive to the ABA agonist quinabactin, which inhibited tomato seed germination. Indeed, the chemical activation of ABA signalling induced by quinabactin was able to activate stress-responsive genes. Both dimeric and monomeric tomato receptors were functional in Arabidopsis plant cells, but only overexpression of monomeric-type receptors conferred enhanced drought resistance. In summary, gene expression analyses, and chemical and transgenic approaches revealed distinct properties of tomato PYR/PYL/RCAR ABA receptors that might have biotechnological implications. PMID:24863435

  4. Macroscopic modeling of plant water uptake: soil and root resistances

    NASA Astrophysics Data System (ADS)

    Vogel, Tomas; Votrubova, Jana; Dohnal, Michal; Dusek, Jaromir

    2014-05-01

    The macroscopic physically-based plant root water uptake (RWU) model, based on water-potential-gradient formulation (Vogel et al., 2013), was used to simulate the observed soil-plant-atmosphere interactions at a forest site located in a temperate humid climate of central Europe and to gain an improved insight into the mutual interplay of RWU parameters that affects the soil water distribution in the root zone. In the applied RWU model, the uptake rates are directly proportional to the potential gradient and indirectly proportional to the local soil and root resistances to water flow. The RWU algorithm is implemented in a one-dimensional dual-continuum model of soil water flow based on Richards' equation. The RWU model is defined by four parameters (root length density distribution, average active root radius, radial root resistance, and the threshold value of the root xylem potential). In addition, soil resistance to water extraction by roots is related to soil hydraulic conductivity function and actual soil water content. The RWU model is capable of simulating both the compensatory root water uptake, in situations when reduced uptake from dry layers is compensated by increased uptake from wetter layers, and the root-mediated hydraulic redistribution of soil water, contributing to more natural soil moisture distribution throughout the root zone. The present study focusses on the sensitivity analysis of the combined soil water flow and RWU model responses in respect to variations of RWU model parameters. Vogel T., M. Dohnal, J. Dusek, J. Votrubova, and M. Tesar. 2013. Macroscopic modeling of plant water uptake in a forest stand involving root-mediated soil-water redistribution. Vadose Zone Journal, 12, 10.2136/vzj2012.0154.

  5. Aquatic hyphomycetes as endophytes of riparian plant roots.

    PubMed

    Sati, S C; Belwal, M

    2005-01-01

    Eighteen species of aquatic hyphomycetes were recorded as root endophytes in roots of living plants including grasses and pteridophytes from wet fields near ravine areas. Alatospora acuminata, A. pulchella, Acaulopage tetraceros, Anguillospora crassa, Campylospora chaetocladia, Lemonniera cornuta, L. pseudofloscula, L. terrestris, Pestalotiopsis submersus and Tetrachaetum elegans were found for the first time as root endophytes. A. longissima, Campylospora purvula, Clavariopsis aquatica, Cylindrocarpon aquaticum, Heliscus lugdunensis, Lunulospora curvula, Tetracladium marchalianum and T. setigerum, which were known previously as root endophytes, are reported here on new hosts. Maximum occurrence was found in November and December. PMID:16389955

  6. Light as stress factor to plant roots – case of root halotropism

    PubMed Central

    Yokawa, Ken; Fasano, Rossella; Kagenishi, Tomoko; Baluška, František

    2014-01-01

    Despite growing underground, largely in darkness, roots emerge to be very sensitive to light. Recently, several important papers have been published which reveal that plant roots not only express all known light receptors but also that their growth, physiology and adaptive stress responses are light-sensitive. In Arabidopsis, illumination of roots speeds-up root growth via reactive oxygen species-mediated and F-actin dependent process. On the other hand, keeping Arabidopsis roots in darkness alters F-actin distribution, polar localization of PIN proteins as well as polar transport of auxin. Several signaling components activated by phytohormones are overlapping with light-related signaling cascade. We demonstrated that the sensitivity of roots to salinity is altered in the light-grown Arabidopsis roots. Particularly, light-exposed roots are less effective in their salt-avoidance behavior known as root halotropism. Here we discuss these new aspects of light-mediated root behavior from cellular, physiological and evolutionary perspectives. PMID:25566292

  7. A new physical interpretation of plant root capacitance

    PubMed Central

    Bengough, Anthony G.

    2012-01-01

    Capacitance has been used as a non-destructive measure of root system size for 30 years. The equipment required is cheap and simple to apply in both field and laboratory. Good linear correlations have been reported between capacitance and root mass. A model by F. N. Dalton, predicting a linear relationship between these two variables, has become accepted widely. This model was tested for barley (Hordeum vulgare) grown hydroponically using treatments that included: raising roots out of solution, cutting roots at positions below the solution surface, and varying the distance between plant electrode and the solution surface. Although good linear correlations were found between capacitance and mass for whole root systems, when roots were raised out of solution capacitances were not linearly related to submerged root mass. Excision of roots in the solution had negligible effect on the measured capacitance. These latter observations conflict with Dalton’s model. Capacitance correlated linearly with the sum of root cross-sectional areas at the solution surface and inversely with distance between plant electrode and solution surface. A new model for capacitance is proposed that is consistent with these observations. PMID:23028023

  8. Silicon Enhances Water Stress Tolerance by Improving Root Hydraulic Conductance in Solanum lycopersicum L.

    PubMed Central

    Shi, Yu; Zhang, Yi; Han, Weihua; Feng, Ru; Hu, Yanhong; Guo, Jia; Gong, Haijun

    2016-01-01

    Silicon (Si) can improve drought tolerance in plants, but the mechanism is still not fully understood. Previous research has been concentrating on Si’s role in leaf water maintenance in Si accumulators, while little information is available on its role in water uptake and in less Si-accumulating plants. Here, we investigated the effects of Si on root water uptake and its role in decreasing oxidative damage in relation to root hydraulic conductance in tomato (Solanum lycopersicum ‘Zhongza No.9’) under water stress. Tomato seedlings were subjected to water stress induced by 10% (w/v) polyethylene glycol-6000 in the absence or presence of 2.5 mM added silicate. The results showed that Si addition ameliorated the inhibition in tomato growth and photosynthesis, and improved water status under water stress. The root hydraulic conductance of tomato plants was decreased under water stress, and it was significantly increased by added Si. There was no significant contribution of osmotic adjustment in Si-enhanced root water uptake under water stress. The transcriptions of plasma membrane aquaporin genes were not obviously changed by Si under water stress. Water stress increased the production of reactive oxygen species and induced oxidative damage, while added Si reversed these. In addition, Si addition increased the activities of superoxide dismutase and catalase and the levels of ascorbic acid and glutathione in the roots under stress. It is concluded that Si enhances the water stress tolerance via enhancing root hydraulic conductance and water uptake in tomato plants. Si-mediated decrease in membrane oxidative damage may have contributed to the enhanced root hydraulic conductance. PMID:26941762

  9. Silicon Enhances Water Stress Tolerance by Improving Root Hydraulic Conductance in Solanum lycopersicum L.

    PubMed

    Shi, Yu; Zhang, Yi; Han, Weihua; Feng, Ru; Hu, Yanhong; Guo, Jia; Gong, Haijun

    2016-01-01

    Silicon (Si) can improve drought tolerance in plants, but the mechanism is still not fully understood. Previous research has been concentrating on Si's role in leaf water maintenance in Si accumulators, while little information is available on its role in water uptake and in less Si-accumulating plants. Here, we investigated the effects of Si on root water uptake and its role in decreasing oxidative damage in relation to root hydraulic conductance in tomato (Solanum lycopersicum 'Zhongza No.9') under water stress. Tomato seedlings were subjected to water stress induced by 10% (w/v) polyethylene glycol-6000 in the absence or presence of 2.5 mM added silicate. The results showed that Si addition ameliorated the inhibition in tomato growth and photosynthesis, and improved water status under water stress. The root hydraulic conductance of tomato plants was decreased under water stress, and it was significantly increased by added Si. There was no significant contribution of osmotic adjustment in Si-enhanced root water uptake under water stress. The transcriptions of plasma membrane aquaporin genes were not obviously changed by Si under water stress. Water stress increased the production of reactive oxygen species and induced oxidative damage, while added Si reversed these. In addition, Si addition increased the activities of superoxide dismutase and catalase and the levels of ascorbic acid and glutathione in the roots under stress. It is concluded that Si enhances the water stress tolerance via enhancing root hydraulic conductance and water uptake in tomato plants. Si-mediated decrease in membrane oxidative damage may have contributed to the enhanced root hydraulic conductance. PMID:26941762

  10. Fungal root endophytes of the carnivorous plant Drosera rotundifolia.

    PubMed

    Quilliam, Richard S; Jones, David L

    2010-06-01

    As carnivorous plants acquire substantial amounts of nutrients from the digestion of their prey, mycorrhizal associations are considered to be redundant; however, fungal root endophytes have rarely been examined. As endophytic fungi can have profound impacts on plant communities, we aim to determine the extent of fungal root colonisation of the carnivorous plant Drosera rotundifolia at two points in the growing season (spring and summer). We have used a culture-dependent method to isolate fungal endophytes and diagnostic polymerase chain reaction methods to determine arbuscular mycorrhizal fungi colonisation. All of the roots sampled contained culturable fungal root endophytes; additionally, we have provided molecular evidence that they also host arbuscular mycorrhizal fungi. Colonisation showed seasonal differences: Roots in the spring were colonised by Articulospora tetracladia, two isolates of uncultured ectomycorrhizal fungi, an unidentified species of fungal endophyte and Trichoderma viride, which was present in every plant sampled. In contrast, roots in the summer were colonised by Alatospora acuminata, an uncultured ectomycorrhizal fungus, Penicillium pinophilum and an uncultured fungal clone. Although the functional roles of fungal endophytes of D. rotundifolia are unknown, colonisation may (a) confer abiotic stress tolerance, (b) facilitate the acquisition of scarce nutrients particularly at the beginning of the growing season or (c) play a role in nutrient signalling between root and shoot. PMID:20012108

  11. Tree root systems competing for soil moisture in a 3D soil-plant model

    NASA Astrophysics Data System (ADS)

    Manoli, Gabriele; Bonetti, Sara; Domec, Jean-Christophe; Putti, Mario; Katul, Gabriel; Marani, Marco

    2014-04-01

    Competition for water among multiple tree rooting systems is investigated using a soil-plant model that accounts for soil moisture dynamics and root water uptake (RWU), whole plant transpiration, and leaf-level photosynthesis. The model is based on a numerical solution to the 3D Richards equation modified to account for a 3D RWU, trunk xylem, and stomatal conductances. The stomatal conductance is determined by combining a conventional biochemical demand formulation for photosynthesis with an optimization hypothesis that selects stomatal aperture so as to maximize carbon gain for a given water loss. Model results compare well with measurements of soil moisture throughout the rooting zone, of total sap flow in the trunk xylem, as well as of leaf water potential collected in a Loblolly pine forest. The model is then used to diagnose plant responses to water stress in the presence of competing rooting systems. Unsurprisingly, the overlap between rooting zones is shown to enhance soil drying. However, the 3D spatial model yielded transpiration-bulk root-zone soil moisture relations that do not deviate appreciably from their proto-typical form commonly assumed in lumped eco-hydrological models. The increased overlap among rooting systems primarily alters the timing at which the point of incipient soil moisture stress is reached by the entire soil-plant system.

  12. Using Hairy Roots for Production of Valuable Plant Secondary Metabolites.

    PubMed

    Tian, Li

    2015-01-01

    Plants synthesize a wide variety of natural products, which are traditionally termed secondary metabolites and, more recently, coined specialized metabolites. While these chemical compounds are employed by plants for interactions with their environment, humans have long since explored and exploited plant secondary metabolites for medicinal and practical uses. Due to the tissue-specific and low-abundance accumulation of these metabolites, alternative means of production in systems other than intact plants are sought after. To this end, hairy root culture presents an excellent platform for producing valuable secondary metabolites. This chapter will focus on several major groups of secondary metabolites that are manufactured by hairy roots established from different plant species. Additionally, the methods for preservations of hairy roots will also be reviewed. PMID:25583225

  13. Enhanced root production in Haplopappus gracilis grown under spaceflight conditions

    NASA Technical Reports Server (NTRS)

    Levine, H. G.; Krikorian, A. D.

    1996-01-01

    The production and growth of roots in two aseptically maintained clonal populations of Haplopappus gracilis (family Compositae), each with a distinctive pattern of root production, were studied after they had been exposed to space for 5 days aboard a NASA Space Shuttle. Total root production of both populations was 67-95% greater when compared with their Earth-grown controls. Roots were generated: (1) laterally from pre-formed roots, the tips of which had been severed at the time of plantlet insertion into a "horticultural foam" substrate supplied with a nutrient solution; (2) adventitiously from the basal or cut-end portion of shoots; (3) de novo, i.e. from primordial which were non-existent at the outset of the experiment. Roots grew in all directions in space but were uniformly positively gravitropic in ground controls. In space and on Earth, both clonal populations maintained their clone-specific root formation and growth characteristics and produced an equivalent amount of tissue when compared to each other. As on Earth, and as expected, there were fewer and shorter roots on plantlets that formed floral buds. The significance of altered moisture distribution in the "horticultural foam" substrate in space for root growth and the significance of our findings for growing plants in altered gravity environments are discussed.

  14. Combinatorially selected defense peptides protect plant roots from pathogen infection

    PubMed Central

    Fang, Zhiwei David; Laskey, James G.; Huang, Shaoxing; Bilyeu, Kristin D.; Morris, Roy O.; Schmidt, Francis J.; English, James T.

    2006-01-01

    Agricultural productivity and sustainability are continually challenged by emerging and indigenous pathogens. Currently, many pathogens can be combated only with biocides or environmentally dangerous fumigants. Here, we report a rapid and pathogen-specific strategy to reduce infection by organisms that target plant roots. Combinatorially selected defense peptides, previously shown to effect premature encystment of Phytophthora capsici zoospores, were fused to maize cytokinin oxidase/dehydrogenase as a display scaffold. When expressed in tomato roots, the peptide-scaffold constructs were secreted and accumulated to sufficient concentrations in the rhizosphere to induce zoospore encystment and thereby deter taxis to the root surface. Pathogen infection was significantly inhibited in roots expressing bioactive peptides fused to the maize cytokinin oxidase/dehydrogenase scaffold. This peptide-delivery technology is broadly applicable for rapid development of plant defense attributes against plant pathogens. PMID:17030803

  15. Root exudates drive interspecific facilitation by enhancing nodulation and N2 fixation.

    PubMed

    Li, Bai; Li, Yu-Ying; Wu, Hua-Mao; Zhang, Fang-Fang; Li, Chun-Jie; Li, Xue-Xian; Lambers, Hans; Li, Long

    2016-06-01

    Plant diversity in experimental systems often enhances ecosystem productivity, but the mechanisms causing this overyielding are only partly understood. Intercropping faba beans (Vicia faba L.) and maize (Zea mays L.) result in overyielding and also, enhanced nodulation by faba beans. By using permeable and impermeable root barriers in a 2-y field experiment, we show that root-root interactions between faba bean and maize significantly increase both nodulation and symbiotic N2 fixation in intercropped faba bean. Furthermore, root exudates from maize promote faba bean nodulation, whereas root exudates from wheat and barley do not. Thus, a decline of soil nitrate concentrations caused by intercropped cereals is not the sole mechanism for maize promoting faba bean nodulation. Intercropped maize also caused a twofold increase in exudation of flavonoids (signaling compounds for rhizobia) in the systems. Roots of faba bean treated with maize root exudates exhibited an immediate 11-fold increase in the expression of chalcone-flavanone isomerase (involved in flavonoid synthesis) gene together with a significantly increased expression of genes mediating nodulation and auxin response. After 35 d, faba beans treated with maize root exudate continued to show up-regulation of key nodulation genes, such as early nodulin 93 (ENOD93), and promoted nitrogen fixation. Our results reveal a mechanism for how intercropped maize promotes nitrogen fixation of faba bean, where maize root exudates promote flavonoid synthesis in faba bean, increase nodulation, and stimulate nitrogen fixation after enhanced gene expression. These results indicate facilitative root-root interactions and provide a mechanism for a positive relationship between species diversity and ecosystem productivity. PMID:27217575

  16. Humic Acids Isolated from Earthworm Compost Enhance Root Elongation, Lateral Root Emergence, and Plasma Membrane H+-ATPase Activity in Maize Roots1

    PubMed Central

    Canellas, Luciano Pasqualoto; Olivares, Fabio Lopes; Okorokova-Façanha, Anna L.; Façanha, Arnoldo Rocha

    2002-01-01

    Earthworms (Eisenia foetida) produce humic substances that can influence plant growth by mechanisms that are not yet clear. In this work, we investigated the effects of humic acids (HAs) isolated from cattle manure earthworm compost on the earliest stages of lateral root development and on the plasma membrane H+-ATPase activity. These HAs enhance the root growth of maize (Zea mays) seedlings in conjunction with a marked proliferation of sites of lateral root emergence. They also stimulate the plasma membrane H+-ATPase activity, apparently associated with an ability to promote expression of this enzyme. In addition, structural analysis reveals the presence of exchangeable auxin groups in the macrostructure of the earthworm compost HA. These results may shed light on the hormonal activity that has been postulated for these humic substances. PMID:12481077

  17. Deep rooting conferred by DEEPER ROOTING 1 enhances rice yield in paddy fields.

    PubMed

    Arai-Sanoh, Yumiko; Takai, Toshiyuki; Yoshinaga, Satoshi; Nakano, Hiroshi; Kojima, Mikiko; Sakakibara, Hitoshi; Kondo, Motohiko; Uga, Yusaku

    2014-01-01

    To clarify the effect of deep rooting on grain yield in rice (Oryza sativa L.) in an irrigated paddy field with or without fertilizer, we used the shallow-rooting IR64 and the deep-rooting Dro1-NIL (a near-isogenic line homozygous for the Kinandang Patong allele of DEEPER ROOTING 1 (DRO1) in the IR64 genetic background). Although total root length was similar in both lines, more roots were distributed within the lower soil layer of the paddy field in Dro1-NIL than in IR64, irrespective of fertilizer treatment. At maturity, Dro1-NIL showed approximately 10% higher grain yield than IR64, irrespective of fertilizer treatment. Higher grain yield of Dro1-NIL was mainly due to the increased 1000-kernel weight and increased percentage of ripened grains, which resulted in a higher harvest index. After heading, the uptake of nitrogen from soil and leaf nitrogen concentration were higher in Dro1-NIL than in IR64. At the mid-grain-filling stage, Dro1-NIL maintained higher cytokinin fluxes from roots to shoots than IR64. These results suggest that deep rooting by DRO1 enhances nitrogen uptake and cytokinin fluxes at late stages, resulting in better grain filling in Dro1-NIL in a paddy field in this study. PMID:24988911

  18. High resolution modeling of water and nutrient uptake by plant roots: at a scale from single root to root system

    NASA Astrophysics Data System (ADS)

    Abesha, Betiglu; Vanderborght, Jan; Javaux, Mathieu; Schnepf, Andrea; Vereecken, Harry

    2014-05-01

    The uptake of nutrients by plant roots is a multiscale problem. At the small scale, nutrient fluxes towards single roots lead to strong gradients in nutrient concentrations around single roots. At the scale of the root system and soil profile, nutrient fluxes are generated by water fluxes and variations in nutrient uptake due to spatially varying root density, nutrient concentrations and water contents. In this contribution, we present a numerical simulation model that describes the processes at the scale of a single root and the scale of the entire root system simultaneously. Water flow and nutrient transport in the soil are described by the 3-D Richards and advection-dispersion equations, respectively. Water uptake by a root segment is simulated based on the difference between the soil water potential at the soil root interface and in the xylem tissue. The xylem water potential is derived from solving a set of flow equations that describe flow in the root network (Javaux et al., 2008). Nutrient uptake by a segment is simulated as a function of the nutrient concentration at the soil-root interface using a nonlinear Michaelis-Menten equation. An accurate description of the nutrient concentrations gradients around single roots requires a spatial resolution in the sub mm scale and is therefore not feasible for simulations of the entire root system or soil profile. In order to address this problem, a 1-D axisymmetric model (Barber and Cushman, 1981) was used to describe nutrient transport towards a single root segment. The network of connected cylindrical models was coupled to a 3-D regular grid that was used to solve the flow and transport equations at the root system scale. The coupling was done by matching the fluxes across the interfaces of the voxels of the 3-D grid that contain root segments with the fluxes at the outer boundaries of the cylindrical domains and by matching the sink terms in these voxels with uptake by the root segments. To demonstrate the

  19. Composite Cucurbita pepo plants with transgenic roots as a tool to study root development

    PubMed Central

    Ilina, Elena L.; Logachov, Anton A.; Laplaze, Laurent; Demchenko, Nikolay P.; Pawlowski, Katharina; Demchenko, Kirill N.

    2012-01-01

    Background and Aims In most plant species, initiation of lateral root primordia occurs above the elongation zone. However, in cucurbits and some other species, lateral root primordia initiation and development takes place in the apical meristem of the parental root. Composite transgenic plants obtained by Agrobacterium rhizogenes-mediated transformation are known as a suitable model to study root development. The aim of the present study was to establish this transformation technique for squash. Methods The auxin-responsive promoter DR5 was cloned into the binary vectors pKGW-RR-MGW and pMDC162-GFP. Incorporation of 5-ethynyl-2′-deoxyuridine (EdU) was used to evaluate the presence of DNA-synthesizing cells in the hypocotyl of squash seedlings to find out whether they were suitable for infection. Two A. rhizogenes strains, R1000 and MSU440, were used. Roots containing the respective constructs were selected based on DsRED1 or green fluorescent protein (GFP) fluorescence, and DR5::Egfp-gusA or DR5::gusA insertion, respectively, was verified by PCR. Distribution of the response to auxin was visualized by GFP fluorescence or β-glucuronidase (GUS) activity staining and confirmed by immunolocalization of GFP and GUS proteins, respectively. Key Results Based on the distribution of EdU-labelled cells, it was determined that 6-day-old squash seedlings were suited for inoculation by A. rhizogenes since their root pericycle and the adjacent layers contain enough proliferating cells. Agrobacterium rhizogenes R1000 proved to be the most virulent strain on squash seedlings. Squash roots containing the respective constructs did not exhibit the hairy root phenotype and were morphologically and structurally similar to wild-type roots. Conclusions The auxin response pattern in the root apex of squash resembled that in arabidopsis roots. Composite squash plants obtained by A. rhizogenes-mediated transformation are a good tool for the investigation of root apical meristem

  20. Root ABA Accumulation Enhances Rice Seedling Drought Tolerance under Ammonium Supply: Interaction with Aquaporins

    PubMed Central

    Ding, Lei; Li, Yingrui; Wang, Ying; Gao, Limin; Wang, Min; Chaumont, François; Shen, Qirong; Guo, Shiwei

    2016-01-01

    In previous studies, we demonstrated that ammonium nutrition enhances the drought tolerance of rice seedlings compared to nitrate nutrition and contributes to a higher root water uptake ability. It remains unclear why rice seedlings maintain a higher water uptake ability when supplied with ammonium under drought stress. Here, we focused on the effects of nitrogen form and drought stress on root abscisic acid (ABA) concentration and aquaporin expression using hydroponics experiments and stimulating drought stress with 10% PEG6000. Drought stress decreased the leaf photosynthetic rate and stomatal conductivity and increased the leaf temperature of plants supplied with either ammonium or nitrate, but especially under nitrate supply. After 4 h of PEG treatment, the root protoplast water permeability and the expression of root PIP and TIP genes decreased in plants supplied with ammonium or nitrate. After 24 h of PEG treatment, the root hydraulic conductivity, the protoplast water permeability, and the expression of some aquaporin genes increased in plants supplied with ammonium compared to those under non-PEG treatment. Root ABA accumulation was induced by 24 h of PEG treatment, especially in plants supplied with ammonium. The addition of exogenous ABA decreased the expression of PIP and TIP genes under non-PEG treatment but increased the expression of some of them under PEG treatment. We concluded that drought stress induced a down-regulation of aquaporin expression, which appeared earlier than did root ABA accumulation. With continued drought stress, aquaporin expression and activity increased due to root ABA accumulation in plants supplied with ammonium. PMID:27559341

  1. Root ABA Accumulation Enhances Rice Seedling Drought Tolerance under Ammonium Supply: Interaction with Aquaporins.

    PubMed

    Ding, Lei; Li, Yingrui; Wang, Ying; Gao, Limin; Wang, Min; Chaumont, François; Shen, Qirong; Guo, Shiwei

    2016-01-01

    In previous studies, we demonstrated that ammonium nutrition enhances the drought tolerance of rice seedlings compared to nitrate nutrition and contributes to a higher root water uptake ability. It remains unclear why rice seedlings maintain a higher water uptake ability when supplied with ammonium under drought stress. Here, we focused on the effects of nitrogen form and drought stress on root abscisic acid (ABA) concentration and aquaporin expression using hydroponics experiments and stimulating drought stress with 10% PEG6000. Drought stress decreased the leaf photosynthetic rate and stomatal conductivity and increased the leaf temperature of plants supplied with either ammonium or nitrate, but especially under nitrate supply. After 4 h of PEG treatment, the root protoplast water permeability and the expression of root PIP and TIP genes decreased in plants supplied with ammonium or nitrate. After 24 h of PEG treatment, the root hydraulic conductivity, the protoplast water permeability, and the expression of some aquaporin genes increased in plants supplied with ammonium compared to those under non-PEG treatment. Root ABA accumulation was induced by 24 h of PEG treatment, especially in plants supplied with ammonium. The addition of exogenous ABA decreased the expression of PIP and TIP genes under non-PEG treatment but increased the expression of some of them under PEG treatment. We concluded that drought stress induced a down-regulation of aquaporin expression, which appeared earlier than did root ABA accumulation. With continued drought stress, aquaporin expression and activity increased due to root ABA accumulation in plants supplied with ammonium. PMID:27559341

  2. Root Zone Respiration on Hydroponically Grown Wheat Plant Systems

    NASA Technical Reports Server (NTRS)

    Soler-Crespo, R. A.; Monje, O. A.

    2010-01-01

    Root respiration is a biological phenomenon that controls plant growth and physiological development during a plant's lifespan. This process is dependent on the availability of oxygen in the system where the plant is located. In hydroponic systems, where plants are submerged in a solution containing vital nutrients but no type of soil, the availability of oxygen arises from the dissolved oxygen concentration in the solution. This oxygen concentration is dependent on the , gas-liquid interface formed on the upper surface of the liquid, as given by Henry's Law, depending on pressure and temperature conditions. Respiration rates of the plants rise as biomass and root zone increase with age. The respiration rate of Apogee wheat plants (Triticum aestivum) was measured as a function of light intensity (catalytic for photosynthesis) and CO2 concentration to determine their effect on respiration rates. To determine their effects on respiration rate and plant growth microbial communities were introduced into the system, by Innoculum. Surfactants were introduced, simulating gray-water usage in space, as another factor to determine their effect on chemical oxygen demand of microbials and on respiration rates of the plants. It is expected to see small effects from changes in CO2 concentration or light levels, and to see root respiration decrease in an exponential manner with plant age and microbial activity.

  3. Regulation of plant root system architecture: implications for crop advancement.

    PubMed

    Rogers, Eric D; Benfey, Philip N

    2015-04-01

    Root system architecture (RSA) plays a major role in plant fitness, crop performance, and grain yield yet only recently has this role been appreciated. RSA describes the spatial arrangement of root tissue within the soil and is therefore crucial to nutrient and water uptake. Recent studies have identified many of the genetic and environmental factors influencing root growth that contribute to RSA. Some of the identified genes have the potential to limit crop loss caused by environmental extremes and are currently being used to confer drought tolerance. It is hypothesized that manipulating these and other genes that influence RSA will be pivotal for future crop advancements worldwide. PMID:25448235

  4. Nitrate reductase-mediated NO production enhances Cd accumulation in Panax notoginseng roots by affecting root cell wall properties.

    PubMed

    Kan, Qi; Wu, Wenwei; Yu, Wenqian; Zhang, Jiarong; Xu, Jin; Rengel, Zed; Chen, Limei; Cui, Xiuming; Chen, Qi

    2016-04-01

    Panax notoginseng (Burk) F. H. Chen is a traditional medicinal herb in China. However, the high capacity of its roots to accumulate cadmium (Cd) poses a potential risk to human health. Although there is some evidence for the involvement of nitric oxide (NO) in mediating Cd toxicity, the origin of Cd-induced NO and its function in plant responses to Cd remain unknown. In this study, we examined NO synthesis and its role in Cd accumulation in P. notoginseng roots. Cd-induced NO production was significantly decreased by application of the nitrate reductase inhibitor tungstate but not the nitric oxide synthase inhibitor L-NAME (N(G)-methyl-l-arginine acetate), indicating that nitrate reductase is the major contributor to Cd-induced NO production in P. notoginseng roots. Under conditions of Cd stress, sodium nitroprusside (SNP, an NO donor) increased Cd accumulation in root cell walls but decreased Cd translocation to the shoot. In contrast, the NO scavenger cPTIO (2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide) and tungstate both significantly decreased NO-increased Cd retention in root cell walls. The amounts of hemicellulose 1 and pectin, together with pectin methylesterase activity, were increased with the addition of SNP but were decreased by cPTIO and tungstate. Furthermore, increases or decreases in hemicellulose 1 and pectin contents as well as pectin methylesterase activity fit well with the increased or decreased retention of Cd in the cell walls of P. notoginseng roots. The results suggest that nitrate reductase-mediated NO production enhances Cd retention in P. notoginseng roots by modulating the properties of the cell wall. PMID:26956919

  5. DynamicRoots: A Software Platform for the Reconstruction and Analysis of Growing Plant Roots

    PubMed Central

    Symonova, Olga; Topp, Christopher N.; Edelsbrunner, Herbert

    2015-01-01

    We present a software platform for reconstructing and analyzing the growth of a plant root system from a time-series of 3D voxelized shapes. It aligns the shapes with each other, constructs a geometric graph representation together with the function that records the time of growth, and organizes the branches into a hierarchy that reflects the order of creation. The software includes the automatic computation of structural and dynamic traits for each root in the system enabling the quantification of growth on fine-scale. These are important advances in plant phenotyping with applications to the study of genetic and environmental influences on growth. PMID:26030757

  6. Role of root microbiota in plant productivity.

    PubMed

    Tkacz, Andrzej; Poole, Philip

    2015-04-01

    The growing human population requires increasing amounts of food, but modern agriculture has limited possibilities for increasing yields. New crop varieties may be bred to have increased yields and be more resistant to environmental stress and pests. However, they still require fertilization to supplement essential nutrients that are normally limited in the soil. Soil microorganisms present an opportunity to reduce the requirement for inorganic fertilization in agriculture. Microorganisms, due to their enormous genetic pool, are also a potential source of biochemical reactions that recycle essential nutrients for plant growth. Microbes that associate with plants can be considered to be part of the plant's pan-genome. Therefore, it is essential for us to understand microbial community structure and their 'metagenome' and how it is influenced by different soil types and crop varieties. In the future we may be able to modify and better utilize the soil microbiota potential for promoting plant growth. PMID:25908654

  7. Hormonal interplay during adventitious root formation in flooded tomato plants.

    PubMed

    Vidoz, Maria Laura; Loreti, Elena; Mensuali, Anna; Alpi, Amedeo; Perata, Pierdomenico

    2010-08-01

    Soil flooding, which results in a decline in the availability of oxygen to submerged organs, negatively affects the growth and productivity of most crops. Although tomato (Solanum lycopersicum) is known for its sensitivity to waterlogging, its ability to produce adventitious roots (ARs) increases plant survival when the level of oxygen is decreased in the root zone. Ethylene entrapment by water may represent the first warning signal to the plant indicating waterlogging. We found that treatment with the ethylene biosynthesis inhibitor aminoethoxyvinylglycine (AVG) and the auxin transport inhibitor 1-naphthylphthalamic acid (NPA) resulted in a reduction of AR formation in waterlogged plants. We observed that ethylene, perceived by the Never Ripe receptor, stimulated auxin transport. In a process requiring the Diageotropica gene, auxin accumulation in the stem triggered additional ethylene synthesis, which further stimulated a flux of auxin towards to the flooded parts of the plant. Auxin accumulation in the base of the plant induces growth of pre-formed root initials. This response of tomato plants results in a new root system that is capable of replacing the original one when it has been damaged by submergence. PMID:20497380

  8. 2,4-diacetylphloroglucinol alters plant root development.

    PubMed

    Brazelton, Jessica N; Pfeufer, Emily E; Sweat, Teresa A; Gardener, Brian B McSpadden; Coenen, Catharina

    2008-10-01

    Pseudomonas fluorescens isolates containing the phlD gene can protect crops from root pathogens, at least in part through production of the antibiotic 2,4-diacetylphloroglucinol (DAPG). However, the action mechanisms of DAPG are not fully understood, and effects of this antibiotic on host root systems have not been characterized in detail. DAPG inhibited primary root growth and stimulated lateral root production in tomato seedlings. Roots of the auxin-resistant diageotropica mutant of tomato demonstrated reduced DAPG sensitivity with regards to inhibition of primary root growth and induction of root branching. Additionally, applications of exogenous DAPG, at concentrations previously found in the rhizosphere of plants inoculated with DAPG-producing pseudomonads, inhibited the activation of an auxin-inducible GH3 promoter::luciferase reporter gene construct in transgenic tobacco hypocotyls. In this model system, supernatants of 17 phlD+ P. fluorescens isolates had inhibitory effects on luciferase activity similar to synthetic DAPG. In addition, a phlD() mutant strain, unable to produce DAPG, demonstrated delayed inhibitory effects compared with the parent wild-type strain. These results indicate that DAPG can alter crop root architecture by interacting with an auxin-dependent signaling pathway. PMID:18785830

  9. Root exudates drive interspecific facilitation by enhancing nodulation and N2 fixation

    PubMed Central

    Li, Bai; Li, Yu-Ying; Wu, Hua-Mao; Zhang, Fang-Fang; Li, Chun-Jie; Li, Xue-Xian; Lambers, Hans; Li, Long

    2016-01-01

    Plant diversity in experimental systems often enhances ecosystem productivity, but the mechanisms causing this overyielding are only partly understood. Intercropping faba beans (Vicia faba L.) and maize (Zea mays L.) result in overyielding and also, enhanced nodulation by faba beans. By using permeable and impermeable root barriers in a 2-y field experiment, we show that root–root interactions between faba bean and maize significantly increase both nodulation and symbiotic N2 fixation in intercropped faba bean. Furthermore, root exudates from maize promote faba bean nodulation, whereas root exudates from wheat and barley do not. Thus, a decline of soil nitrate concentrations caused by intercropped cereals is not the sole mechanism for maize promoting faba bean nodulation. Intercropped maize also caused a twofold increase in exudation of flavonoids (signaling compounds for rhizobia) in the systems. Roots of faba bean treated with maize root exudates exhibited an immediate 11-fold increase in the expression of chalcone–flavanone isomerase (involved in flavonoid synthesis) gene together with a significantly increased expression of genes mediating nodulation and auxin response. After 35 d, faba beans treated with maize root exudate continued to show up-regulation of key nodulation genes, such as early nodulin 93 (ENOD93), and promoted nitrogen fixation. Our results reveal a mechanism for how intercropped maize promotes nitrogen fixation of faba bean, where maize root exudates promote flavonoid synthesis in faba bean, increase nodulation, and stimulate nitrogen fixation after enhanced gene expression. These results indicate facilitative root–root interactions and provide a mechanism for a positive relationship between species diversity and ecosystem productivity. PMID:27217575

  10. Role of root microbiota in plant productivity

    PubMed Central

    Tkacz, Andrzej; Poole, Philip

    2015-01-01

    The growing human population requires increasing amounts of food, but modern agriculture has limited possibilities for increasing yields. New crop varieties may be bred to have increased yields and be more resistant to environmental stress and pests. However, they still require fertilization to supplement essential nutrients that are normally limited in the soil. Soil microorganisms present an opportunity to reduce the requirement for inorganic fertilization in agriculture. Microorganisms, due to their enormous genetic pool, are also a potential source of biochemical reactions that recycle essential nutrients for plant growth. Microbes that associate with plants can be considered to be part of the plant’s pan-genome. Therefore, it is essential for us to understand microbial community structure and their ‘metagenome’ and how it is influenced by different soil types and crop varieties. In the future we may be able to modify and better utilize the soil microbiota potential for promoting plant growth. PMID:25908654

  11. Trichoderma spp. Improve growth of Arabidopsis seedlings under salt stress through enhanced root development, osmolite production, and Na⁺ elimination through root exudates.

    PubMed

    Contreras-Cornejo, Hexon Angel; Macías-Rodríguez, Lourdes; Alfaro-Cuevas, Ruth; López-Bucio, José

    2014-06-01

    Salt stress is an important constraint to world agriculture. Here, we report on the potential of Trichoderma virens and T. atroviride to induce tolerance to salt in Arabidopsis seedlings. We first characterized the effect of several salt concentrations on shoot biomass production and root architecture of Arabidopsis seedlings. We found that salt repressed plant growth and root development in a dose-dependent manner by blocking auxin signaling. Analysis of the wild type and eir1, aux1-7, arf7arf19, and tir1abf2abf19 auxin-related mutants revealed a key role for indole-3-acetic acid (IAA) signaling in mediating salt tolerance. We also found that T. virens (Tv29.8) and T. atroviride (IMI 206040) promoted plant growth in both normal and saline conditions, which was related to the induction of lateral roots and root hairs through auxin signaling. Arabidopsis seedlings grown under saline conditions inoculated with Trichoderma spp. showed increased levels of abscissic acid, L-proline, and ascorbic acid, and enhanced elimination of Na⁺ through root exudates. Our data show the critical role of auxin signaling and root architecture to salt tolerance in Arabidopsis and suggest that these fungi may enhance the plant IAA level as well as the antioxidant and osmoprotective status of plants under salt stress. PMID:24502519

  12. Enhanced hyphal growth of arbuscular mycorrhizae by root exudates derived from high R/FR treated Lotus japonicus.

    PubMed

    Nagata, Maki; Yamamoto, Naoya; Miyamoto, Taro; Shimomura, Aya; Arima, Susumu; Hirsch, Ann M; Suzuki, Akihiro

    2016-06-01

    Red/Far Red (R/FR) sensing positively influences the arbuscular mycorrhizal (AM) symbiosis of both legume and nonlegume plants through jasmonic acid (JA) and strigolactone signaling. We previously reported that root exudates obtained from high R/FR-grown plants contained more strigolactone than low R/FR-grown plants. To determine whether JA and JA derivatives were secreted from roots, we investigated the expression levels of JA-responsive genes in L. japonicus Miyakojima MG20 plants treated with root exudates prepared from either high or low R/FR light-treated plants. The root exudates from high R/FR light-treated plants were found to enhance the expression levels of JA-responsive genes significantly. Moreover, exogenous JA increased AM fungal hyphal elongation as did the root exudates derived from high R/FR-grown L. japonicus plants. We conclude that increased JA accumulation and secretion into root exudates from high R/FR light-grown plants is the best explanation for increased colonization and enhanced mycorrhization under these conditions. PMID:27191935

  13. Fluorescence Imaging of the Cytoskeleton in Plant Roots.

    PubMed

    Dyachok, Julia; Paez-Garcia, Ana; Yoo, Cheol-Min; Palanichelvam, Karuppaiah; Blancaflor, Elison B

    2016-01-01

    During the past two decades the use of live cytoskeletal probes has increased dramatically due to the introduction of the green fluorescent protein. However, to make full use of these live cell reporters it is necessary to implement simple methods to maintain plant specimens in optimal growing conditions during imaging. To image the cytoskeleton in living Arabidopsis roots, we rely on a system involving coverslips coated with nutrient supplemented agar where the seeds are directly germinated. This coverslip system can be conveniently transferred to the stage of a confocal microscope with minimal disturbance to the growth of the seedling. For roots with a larger diameter such as Medicago truncatula, seeds are first germinated in moist paper, grown vertically in between plastic trays, and roots mounted on glass slides for confocal imaging. Parallel with our live cell imaging approaches, we routinely process fixed plant material via indirect immunofluorescence. For these methods we typically use non-embedded vibratome-sectioned and whole mount permeabilized root tissue. The clearly defined developmental regions of the root provide us with an elegant system to further understand the cytoskeletal basis of plant development. PMID:26498783

  14. Is nutrient uptake by plant roots sensitive to the rate of mass flow? Reappraisal of an old chestnut for spatially distributed root systems

    NASA Astrophysics Data System (ADS)

    McMurtrie, R. E.; Näsholm, T.

    2015-12-01

    Numerous modelling papers have considered the contribution of mass flow to nutrient uptake by a single plant root, but few have evaluated its contribution at the scale of an entire root system. We derive equations for nitrogen (N) influx per unit root surface area (J) and N uptake by a single root (U) as functions of soil nitrogen supply, root-length density (RLD) and the velocity of water at the root surface (vo). This model of N uptake by a single root can be used to evaluate N uptake by an entire root system if spatial distributions are known for soil N supply, root biomass and water-uptake velocity. In this paper we show that spatial distributions of RLD and vo can be estimated simultaneously under an optimisation hypothesis (MaxNup, McMurtrie et al. 2012), according to which total root mass and total water uptake are distributed vertically in order to maximise total N uptake. The MaxNup hypothesis leads to equations for optimal vertical profiles of RLD, vo, J and U, maximum rooting depth and the fraction of total available soil nitrogen taken up by the root system. Predicted values of vo are enhanced at depths where nitrogen influx per unit root surface area (J) is more sensitive to vo and diminished at depths where J is less sensitive to vo. Predicted vo is largest at the base of the root system where RLD is lowest, and is smallest in upper soil layers where RLD is highest. MaxNup thus predicts that water uptake will be distributed preferentially to soil depths where it will enhance nitrogen uptake U; this tendency will amplify the sensitivity of total N uptake to total water uptake, compared with strategies where vo is the same for all roots, or where vo is elevated for roots in upper soil layers. Reference McMurtrie RE, Iversen CM, Dewar RC, Medlyn BE, Näsholm T, Pepper DA, Norby RJ. 2012. Plant root distributions and nitrogen uptake predicted by a hypothesis of optimal root foraging. Ecology and Evolution 2: 1235-1250.

  15. Effect of Root System Morphology on Root-sprouting and Shoot-rooting Abilities in 123 Plant Species from Eroded Lands in North-east Spain

    PubMed Central

    GUERRERO-CAMPO, JOAQUÍN; PALACIO, SARA; PÉREZ-RONTOMÉ, CARMEN; MONTSERRAT-MARTÍ, GABRIEL

    2006-01-01

    • Background and Aims The objective of this study was to test whether the mean values of several root morphological variables were related to the ability to develop root-borne shoots and/or shoot-borne roots in a wide range of vascular plants. • Methods A comparative study was carried out on the 123 most common plant species from eroded lands in north-east Spain. After careful excavations in the field, measurements were taken of the maximum root depth, absolute and relative basal root diameter, specific root length (SRL), and the root depth/root lateral spread ratio on at least three individuals per species. Shoot-rooting and root-sprouting were observed in a large number of individuals in many eroded and sedimentary environments. The effect of life history and phylogeny on shoot-rooting and root-sprouting abilities was also analysed. • Key Results The species with coarse and deep tap-roots tended to be root-sprouting and those with fine, fasciculate and long main roots (which generally spread laterally), tended to be shoot-rooting. Phylogeny had an important influence on root system morphology and shoot-rooting and root-sprouting capacities. However, the above relations stood after applying analyses based on phylogenetically independent contrasts (PICs). • Conclusions The main morphological features of the root system of the study species are related to their ability to sprout from their roots and form roots from their shoots. According to the results, such abilities might only be functionally viable in restricted root system morphologies and ecological strategies. PMID:16790468

  16. Abiotic stress responses in plant roots: a proteomics perspective

    PubMed Central

    Ghosh, Dipanjana; Xu, Jian

    2014-01-01

    Abiotic stress conditions adversely affect plant growth, resulting in significant decline in crop productivity. To mitigate and recover from the damaging effects of such adverse environmental conditions, plants have evolved various adaptive strategies at cellular and metabolic levels. Most of these strategies involve dynamic changes in protein abundance that can be best explored through proteomics. This review summarizes comparative proteomic studies conducted with roots of various plant species subjected to different abiotic stresses especially drought, salinity, flood, and cold. The main purpose of this article is to highlight and classify the protein level changes in abiotic stress response pathways specifically in plant roots. Shared as well as stressor-specific proteome signatures and adaptive mechanism(s) are simultaneously described. Such a comprehensive account will facilitate the design of genetic engineering strategies that enable the development of broad-spectrum abiotic stress-tolerant crops. PMID:24478786

  17. Hydraulic resistance of a plant root to water-uptake: A slender-body theory.

    PubMed

    Chen, Kang Ping

    2016-05-01

    A slender-body theory for calculating the hydraulic resistance of a single plant root is developed. The work provides an in-depth discussion on the procedure and the assumptions involved in calculating a root׳s internal hydraulic resistance as well as the physical and the mathematical aspects of the external three-dimensional flow around the tip of a root in a saturated soil and how this flow pattern enhances uptake and reduces hydraulic resistance. Analytical solutions for the flux density distribution on the stele-cortex interface, local water-uptake profile inside the stele core, the overall water-uptake at the base of the stele, and the total hydraulic resistance of a root are obtained in the slender-body limit. It is shown that a key parameter controlling a root's hydraulic resistance is the dimensionless axial conductivity in the stele, which depends on the permeabilities of the stele and the cortex as well as the root's radial and axial dimensions. Three-dimensional tip effect reduces a root's hydraulic resistance by as much as 36% when compared to the radial flow theory of Landsberg and Fowkes. In addition, the total hydraulic resistance cannot be generally decomposed into the direct sum of a radial resistance and an axial resistance. PMID:26920247

  18. Development and recovery of iron deficiency by iron resupply to roots or leaves of strawberry plants.

    PubMed

    Pestana, Maribela; Correia, Pedro José; Saavedra, Teresa; Gama, Florinda; Abadía, Anunciación; de Varennes, Amarilis

    2012-04-01

    Bare-root transplants of strawberry (Fragaria ananassa Duch. cv. 'Selva') were transferred to nutrient solutions with or without iron (Fe). After six weeks of growth, plants grown in solution lacking Fe were chlorotic and showed morphological changes in roots typical of Fe deficiency. Subsequently, four treatments were applied for nine days: plants grown in continued absence of Fe (Fe0); plants grown in continued presence of 10 μM Fe (Fe10); foliar application of ferrous sulphate every two days to chlorotic plants (Fe-leaves); and growth of chlorotic plants in solution with ferrous sulphate (Fe-solution). After six days, the chlorophyll (Chl) content in leaves of Fe-solution plants was similar to that in Fe10 plants. Under the Fe-leaves treatment, a slight regreening of new leaves was observed only by the end of the experiment. After nine days, ferric chelate reductase (FC-R) activity was unchanged in Fe10 but increased in Fe0 plants. The FC-R activity of Fe-solution plants was similar to the initial value for chlorotic plants, whereas it was reduced drastically under the Fe-leaves treatment. The Fe concentration in leaves of Fe0 and Fe10 was similar, whereas the Fe-solution and Fe-leaves treatments enhanced leaf Fe concentration. In contrast to the Fe-solution treatment, foliar application of Fe did not increase the Fe concentration in roots. Under our experimental conditions, FC-R activity in strawberry appeared to be deactivated rapidly by pulses of Fe applied by foliar sprays. Deactivation was slower if Fe was applied directly to roots, which suggested that the plants had greater opportunity to take Fe. PMID:22285409

  19. CLE peptide signaling and nitrogen interactions in plant root development.

    PubMed

    Araya, Takao; von Wirén, Nicolaus; Takahashi, Hideki

    2016-08-01

    The CLAVATA signaling pathway is essential for the regulation of meristem activities in plants. This signaling pathway consists of small signaling peptides of the CLE family interacting with CLAVATA1 and leucine-rich repeat receptor-like kinases (LRR-RLKs). The peptide-receptor relationships determine the specificities of CLE-dependent signals controlling stem cell fate and differentiation that are critical for the establishment and maintenance of shoot and root apical meristems. Plants root systems are highly organized into three-dimensional structures for successful anchoring and uptake of water and mineral nutrients from the soil environment. Recent studies have provided evidence that CLE peptides and CLAVATA signaling pathways play pivotal roles in the regulation of lateral root development and systemic autoregulation of nodulation (AON) integrated with nitrogen (N) signaling mechanisms. Integrations of CLE and N signaling pathways through shoot-root vascular connections suggest that N demand modulates morphological control mechanisms and optimize N uptake as well as symbiotic N fixation in roots. PMID:26994997

  20. Improving rice tolerance to potassium deficiency by enhancing OsHAK16p:WOX11-controlled root development.

    PubMed

    Chen, Guang; Feng, Huimin; Hu, Qingdi; Qu, Hongye; Chen, Aiqun; Yu, Ling; Xu, Guohua

    2015-08-01

    Potassium (K) deficiency in plants confines root growth and decreases root-to-shoot ratio, thus limiting root K acquisition in culture medium. A WUSCHEL-related homeobox (WOX) gene, WOX11, has been reported as an integrator of auxin and cytokinin signalling that regulates root cell proliferation. Here, we report that ectopic expression of WOX11 gene driven by the promoter of OsHAK16 encoding a low-K-enhanced K transporter led to an extensive root system and adventitious roots and more effective tiller numbers in rice. The WOX11-regulated root and shoot phenotypes in the OsHAK16p:WOX11 transgenic lines were supported by K-deficiency-enhanced expression of several RR genes encoding type-A cytokinin-responsive regulators, PIN genes encoding auxin transporters and Aux/IAA genes. In comparison with WT, the transgenic lines showed increases in root biomass, root activity and K concentrations in the whole plants, and higher soluble sugar concentrations in roots particularly under low K supply condition. The improvement of sugar partitioning to the roots by the expression of OsHAK16p:WOX11 was further indicated by increasing the expression of OsSUT1 and OsSUT4 genes in leaf blades and several OsMSTs genes in roots. Expression of OsHAK16p:WOX11 in the rice grown in moderate K-deficient soil increased total K uptake by 72% and grain yield by 24%-32%. The results suggest that enlarging root growth and development by the expression of WOX11 in roots could provide a useful option for increasing K acquisition efficiency and cereal crop productivity in low K soil. PMID:25599895

  1. Rooting depth and distributions of deep-rooted plants in the 200 Area control zone of the Hanford Site

    SciTech Connect

    Klepper, E.L.; Gano, K.A.; Cadwell, L.L.

    1985-01-01

    This study was conducted to document rooting depths and distributions of deep-rooted plants common to the Hanford Site 200-Area plateau. The effort concentrated on excavating plant species suspected of having deep root systems, and species that have been reported in previous studies to contain radionuclides in above ground parts. The information obtained in this study will be useful in modeling radionuclide transport by plants and in designing covers and barriers for decommissioning low-level radioactive waste burial sites. Fourteen species including 58 individual plants were excavated to measure maximum rooting depth and root density distribution (g dry root/dm/sup 3/) through the root zone. Age and canopy volumes of shrubs were also determined. Eight of the 14 species excavated had average rooting depths of 150 cm or more. The two deepest rooted plants were antelope bitterbrush and sagebrush with average depths of 296 and 200 cm, respectively. Gray rabbitbrush had an average rooting depth of 183 cm. Summer annuals, Russian thistle and bursage, had average rooting depths of 172 and 162 cm, respectively. 7 references, 4 figures, 5 tables.

  2. Defense mutualisms enhance plant diversification.

    PubMed

    Weber, Marjorie G; Agrawal, Anurag A

    2014-11-18

    The ability of plants to form mutualistic relationships with animal defenders has long been suspected to influence their evolutionary success, both by decreasing extinction risk and by increasing opportunity for speciation through an expanded realized niche. Nonetheless, the hypothesis that defense mutualisms consistently enhance plant diversification across lineages has not been well tested due to a lack of phenotypic and phylogenetic information. Using a global analysis, we show that the >100 vascular plant families in which species have evolved extrafloral nectaries (EFNs), sugar-secreting organs that recruit arthropod mutualists, have twofold higher diversification rates than families that lack species with EFNs. Zooming in on six distantly related plant clades, trait-dependent diversification models confirmed the tendency for lineages with EFNs to display increased rates of diversification. These results were consistent across methodological approaches. Inference using reversible-jump Markov chain Monte Carlo (MCMC) to model the placement and number of rate shifts revealed that high net diversification rates in EFN clades were driven by an increased number of positive rate shifts following EFN evolution compared with sister clades, suggesting that EFNs may be indirect facilitators of diversification. Our replicated analysis indicates that defense mutualisms put lineages on a path toward increased diversification rates within and between clades, and is concordant with the hypothesis that mutualistic interactions with animals can have an impact on deep macroevolutionary patterns and enhance plant diversity. PMID:25349406

  3. Defense mutualisms enhance plant diversification

    PubMed Central

    Weber, Marjorie G.; Agrawal, Anurag A.

    2014-01-01

    The ability of plants to form mutualistic relationships with animal defenders has long been suspected to influence their evolutionary success, both by decreasing extinction risk and by increasing opportunity for speciation through an expanded realized niche. Nonetheless, the hypothesis that defense mutualisms consistently enhance plant diversification across lineages has not been well tested due to a lack of phenotypic and phylogenetic information. Using a global analysis, we show that the >100 vascular plant families in which species have evolved extrafloral nectaries (EFNs), sugar-secreting organs that recruit arthropod mutualists, have twofold higher diversification rates than families that lack species with EFNs. Zooming in on six distantly related plant clades, trait-dependent diversification models confirmed the tendency for lineages with EFNs to display increased rates of diversification. These results were consistent across methodological approaches. Inference using reversible-jump Markov chain Monte Carlo (MCMC) to model the placement and number of rate shifts revealed that high net diversification rates in EFN clades were driven by an increased number of positive rate shifts following EFN evolution compared with sister clades, suggesting that EFNs may be indirect facilitators of diversification. Our replicated analysis indicates that defense mutualisms put lineages on a path toward increased diversification rates within and between clades, and is concordant with the hypothesis that mutualistic interactions with animals can have an impact on deep macroevolutionary patterns and enhance plant diversity. PMID:25349406

  4. Enhanced Gravitropism of Roots with a Disrupted Cap Actin Cytoskeleton1

    PubMed Central

    Hou, Guichuan; Mohamalawari, Deepti R.; Blancaflor, Elison B.

    2003-01-01

    The actin cytoskeleton has been proposed to be a major player in plant gravitropism. However, understanding the role of actin in this process is far from complete. To address this problem, we conducted an analysis of the effect of Latrunculin B (Lat B), a potent actin-disrupting drug, on root gravitropism using various parameters that included detailed curvature kinetics, estimation of gravitropic sensitivity, and monitoring of curvature development after extended clinorotation. Lat B treatment resulted in a promotion of root curvature after a 90° reorientation in three plant species tested. More significantly, the sensitivity of maize (Zea mays) roots to gravity was enhanced after actin disruption, as determined from a comparison of presentation time of Lat B-treated versus untreated roots. A short 10-min gravistimulus followed by extended rotation on a 1-rpm clinostat resulted in extensive gravitropic responses, manifested as curvature that often exceeded 90°. Application of Lat B to the cap or elongation zone of maize roots resulted in the disruption of the actin cytoskeleton, which was confined to the area of localized Lat B application. Only roots with Lat B applied to the cap displayed the strong curvature responses after extended clinorotation. Our study demonstrates that disrupting the actin cytoskeleton in the cap leads to the persistence of a signal established by a previous gravistimulus. Therefore, actin could function in root gravitropism by providing a mechanism to regulate the proliferation of a gravitropic signal originating from the cap to allow the root to attain its correct orientation or set point angle. PMID:12644685

  5. Change of soil organic matter quality and quantity by deep-rooting plants - a molecular approach

    NASA Astrophysics Data System (ADS)

    Gocke, Martina; Derenne, Sylvie; Anquetil, Christelle; Huguet, Arnaud; Dignac, Marie-France; Rumpel, Cornelia; Wiesenberg, Guido L. B.

    2015-04-01

    Under predicted rising atmospheric CO2 concentration, soils are discussed to potentially act as C sinks. Stability and long-term storage of soil OM are affected by both molecular structure of incorporated organic remains and environmental factors. It is increasingly accepted that roots contribute to significant portions of topsoil OM, whereas their role for C cycling is less known for depths >> 1 m, i.e. the deep subsoil and underlying soil parent material like terrestrial sediments. To trace root-related features and organic remains, transects were sampled from ancient (3-10 ky) and recent calcified roots (rhizoliths) via surrounding sediment towards sediment free of visible root remains, at two sites. At the Nussloch loess-paleosol sequence (SW Germany), transects were collected as intact cores and scanned by X-ray microtomography for visualization of rhizoliths and rhizosphere. Afterwards, cores were cut into concentric slices and, similar to rhizolith and sediment samples from the sandy deep subsoil at Sopron (NW Hungary), analyzed for suberin molecular markers. Suberin biomarkers were found in both recent and ancient root systems, demonstrating their suitability to identify root-derived OM in terrestrial sediments with ages of several tens of ky. Varying relative portions of the respective suberin markers enabled the attribution of Sopron rhizoliths to oak origin, and assessment of the rhizosphere, which extended up to several cm. This confirms recent studies which demonstrated the possible postsedimentary incorporation of considerable amounts of root and rhizomicrobial remains in loess, based on biomarkers deriving either from plants and microorganisms (alkanes, fatty acids) or solely from microorganisms (GDGTs). 3D scanning of Nussloch rhizoliths and surrounding loess showed large channels of former root growth, whereas the root tissue was commonly degraded. Additionally, microtomography enabled assessment of abundant fine calcified roots as well as biopores

  6. A Latex Metabolite Benefits Plant Fitness under Root Herbivore Attack.

    PubMed

    Huber, Meret; Epping, Janina; Schulze Gronover, Christian; Fricke, Julia; Aziz, Zohra; Brillatz, Théo; Swyers, Michael; Köllner, Tobias G; Vogel, Heiko; Hammerbacher, Almuth; Triebwasser-Freese, Daniella; Robert, Christelle A M; Verhoeven, Koen; Preite, Veronica; Gershenzon, Jonathan; Erb, Matthias

    2016-01-01

    Plants produce large amounts of secondary metabolites in their shoots and roots and store them in specialized secretory structures. Although secondary metabolites and their secretory structures are commonly assumed to have a defensive function, evidence that they benefit plant fitness under herbivore attack is scarce, especially below ground. Here, we tested whether latex secondary metabolites produced by the common dandelion (Taraxacum officinale agg.) decrease the performance of its major native insect root herbivore, the larvae of the common cockchafer (Melolontha melolontha), and benefit plant vegetative and reproductive fitness under M. melolontha attack. Across 17 T. officinale genotypes screened by gas and liquid chromatography, latex concentrations of the sesquiterpene lactone taraxinic acid β-D-glucopyranosyl ester (TA-G) were negatively associated with M. melolontha larval growth. Adding purified TA-G to artificial diet at ecologically relevant concentrations reduced larval feeding. Silencing the germacrene A synthase ToGAS1, an enzyme that was identified to catalyze the first committed step of TA-G biosynthesis, resulted in a 90% reduction of TA-G levels and a pronounced increase in M. melolontha feeding. Transgenic, TA-G-deficient lines were preferred by M. melolontha and suffered three times more root biomass reduction than control lines. In a common garden experiment involving over 2,000 T. officinale individuals belonging to 17 different genotypes, high TA-G concentrations were associated with the maintenance of high vegetative and reproductive fitness under M. melolontha attack. Taken together, our study demonstrates that a latex secondary metabolite benefits plants under herbivore attack, a result that provides a mechanistic framework for root herbivore driven natural selection and evolution of plant defenses below ground. PMID:26731567

  7. A Latex Metabolite Benefits Plant Fitness under Root Herbivore Attack

    PubMed Central

    Huber, Meret; Epping, Janina; Schulze Gronover, Christian; Fricke, Julia; Aziz, Zohra; Brillatz, Théo; Swyers, Michael; Köllner, Tobias G.; Vogel, Heiko; Hammerbacher, Almuth; Triebwasser-Freese, Daniella; Robert, Christelle A. M.; Verhoeven, Koen; Preite, Veronica; Gershenzon, Jonathan; Erb, Matthias

    2016-01-01

    Plants produce large amounts of secondary metabolites in their shoots and roots and store them in specialized secretory structures. Although secondary metabolites and their secretory structures are commonly assumed to have a defensive function, evidence that they benefit plant fitness under herbivore attack is scarce, especially below ground. Here, we tested whether latex secondary metabolites produced by the common dandelion (Taraxacum officinale agg.) decrease the performance of its major native insect root herbivore, the larvae of the common cockchafer (Melolontha melolontha), and benefit plant vegetative and reproductive fitness under M. melolontha attack. Across 17 T. officinale genotypes screened by gas and liquid chromatography, latex concentrations of the sesquiterpene lactone taraxinic acid β-D-glucopyranosyl ester (TA-G) were negatively associated with M. melolontha larval growth. Adding purified TA-G to artificial diet at ecologically relevant concentrations reduced larval feeding. Silencing the germacrene A synthase ToGAS1, an enzyme that was identified to catalyze the first committed step of TA-G biosynthesis, resulted in a 90% reduction of TA-G levels and a pronounced increase in M. melolontha feeding. Transgenic, TA-G-deficient lines were preferred by M. melolontha and suffered three times more root biomass reduction than control lines. In a common garden experiment involving over 2,000 T. officinale individuals belonging to 17 different genotypes, high TA-G concentrations were associated with the maintenance of high vegetative and reproductive fitness under M. melolontha attack. Taken together, our study demonstrates that a latex secondary metabolite benefits plants under herbivore attack, a result that provides a mechanistic framework for root herbivore driven natural selection and evolution of plant defenses below ground. PMID:26731567

  8. Aeration for plant root respiration in a tidal marsh

    NASA Astrophysics Data System (ADS)

    Li, Hailong; Li, Ling; Lockington, David

    2005-06-01

    This paper investigates the tidal effects on aeration conditions for plant root respiration in a tidal marsh. We extend the work of Ursino et al. (2004) by using a two-phase model for air and water flows in the marsh. Simulations have been conducted to examine directly the link between the airflow dynamics and the aeration condition in the marsh soil. The results show that the effects of entrapped air on water movement in the vadose zone are significant in certain circumstances. Single-phase models based on Richards' equation, which neglect such effects, may not be adequate for quantifying the aeration condition in tidal marsh. The optimal aeration condition, represented by the maximum of the integral magnitude of tidally advected air mass (TAAM) flux, is found to occur near the tidal creek for the four soil textures simulated. This may explain the observation that some salt marsh plant species grow better near tidal creeks than in the inner marsh areas. Our analyses, based on the two-phase model and predicted TAAM flux magnitude, provide further insight into the "positive feedback" mechanism proposed by Ursino et al. (2004). That is, pioneer plants may grow successfully near the creek where the root aeration condition is optimal. The roots of the pioneer plants can soften and loosen the rhizosphere soil, which increases the evapotranspiration rate, the soil porosity, and absolute permeability and weakens the capillary effects. These, in turn, improve further the root aeration conditions and may lead to colonization by plants less resistant to anaerobic conditions.

  9. Aeration for plant root respiration in a tidal marsh

    NASA Astrophysics Data System (ADS)

    Li, Hailong; Li, Ling; Lockington, David

    2005-06-01

    This paper investigates the tidal effects on aeration conditions for plant root respiration in a tidal marsh. We extend the work of Ursino et al. (2004) by using a two-phase model for air and water flows in the marsh. Simulations have been conducted to examine directly the link between the airflow dynamics and the aeration condition in the marsh soil. The results show that the effects of entrapped air on water movement in the vadose zone are significant in certain circumstances. Single-phase models based on Richards' equation, which neglect such effects, may not be adequate for quantifying the aeration condition in tidal marsh. The optimal aeration condition, represented by the maximum of the integral magnitude of tidally advected air mass (TAAM) flux, is found to occur near the tidal creek for the four soil textures simulated. This may explain the observation that some salt marsh plant species grow better near tidal creeks than in the inner marsh areas. Our analyses, based on the two-phase model and predicted TAAM flux magnitude, provide further insight into the ``positive feedback'' mechanism proposed by Ursino et al. (2004). That is, pioneer plants may grow successfully near the creek where the root aeration condition is optimal. The roots of the pioneer plants can soften and loosen the rhizosphere soil, which increases the evapotranspiration rate, the soil porosity, and absolute permeability and weakens the capillary effects. These, in turn, improve further the root aeration conditions and may lead to colonization by plants less resistant to anaerobic conditions.

  10. COMPREHENSIVE CHEMICAL PROFILING OF GRAMINEOUS PLANT ROOT EXUDATES USING HIGH-RESOLUTION NMR AND MS

    EPA Science Inventory

    Root exudates released into soil have important functions in mobilizing metal micronutrients and for causing selective enrichment of plant beneficial soil microorganisms that colonize the rhizosphere. Analysis of plant root exudates typically has involved chromatographic methods ...

  11. Plant iodine-131 uptake in relation to root concentration as measured in minirhizotron by video camera:

    SciTech Connect

    Moss, K.J.

    1990-09-01

    Glass viewing tubes (minirhizotrons) were placed in the soil beneath native perennial bunchgrass (Agropyron spicatum). The tubes provided access for observing and quantifying plant roots with a miniature video camera and soil moisture estimates by neutron hydroprobe. The radiotracer I-131 was delivered to the root zone at three depths with differing root concentrations. The plant was subsequently sampled and analyzed for I-131. Plant uptake was greater when I-131 was applied at soil depths with higher root concentrations. When I-131 was applied at soil depths with lower root concentrations, plant uptake was less. However, the relationship between root concentration and plant uptake was not a direct one. When I-131 was delivered to deeper soil depths with low root concentrations, the quantity of roots there appeared to be less effective in uptake than the same quantity of roots at shallow soil depths with high root concentration. 29 refs., 6 figs., 11 tabs.

  12. Efficient solution techniques for simulation nutrient uptake by plant roots

    NASA Astrophysics Data System (ADS)

    Abesha, Betiglu; Vanderborght, Jan; Javaux, Mathieu; Schnepf, Andrea; Vereecken, Harry

    2015-04-01

    Water and nutrient transfer to plant roots is determined by processes occurring from the single root to the entire root system. A mechanistic spatially distributed description of these processes would require a sub mm discretization which is computationally not feasible. In this contribution, we present efficient solution techniques to represent accurate nutrient uptake by plant roots. The first solution technique describes nutrient transport towards a single root segment using a 1-D radially axisymmetric model (Barber and Cushman 1981). Transport to the entire root system is represented by a network of connected cylindrical models around the roots. This network of cylinders was coupled to a 3-D regular grid that was used to solve the flow and transport equations in the soil at the root system scale (Javaux et al. 2008). The second technique was a modified time compression approximation (TCA), which can be a simple and reasonably accurate semi-analytical method for predicting cumulative nutrient uptake when the convection flux and diffusion coefficient change over time due to for instance soil drying. The analytical approach presented by Roose et al. (2001) to calculate solute cumulative uptake provides means to analyze cumulative nutrient uptake at a changing diffusive-convective flux over time but with constant convection and diffusion coefficient. This analytical solution was used in TCA framework to predict uptake when convection and diffusion coefficient change over time. We compared cumulative nutrient uptake by the 1D / 3D coupled model with results obtained by spatially highly resolved 3-D model and the approximate analytical solution of Roose et al. (2001). The good agreement between both model approaches allows the use of the 1D/3D coupling approach to simulate water and nutrient transport at the a root system scale with minimal computational cost and good accuracy. This approach also accounts for the effect of transpiration and soil drying on nutrient

  13. Root profile in Multi-layered Dehesas: an approach to plant-to-plant Interaction

    NASA Astrophysics Data System (ADS)

    Rolo, V.; Moreno, G.

    2009-04-01

    Assessing plant-to-plant relationship is a key issue in agroforestry systems. Due to the sessile feature of plants most of these interactions take place within a restricted space, so characterizing the zone where the plant alters its environment is important to find overlapping areas where the facilitation or competition could occur. Main part of plan-to-plant interactions in the dehesa are located at belowground level, thus the main limited resources in Mediterranean ecosystems are soil nutrient and water. Hence a better knowledge of rooting plant profile can be useful to understand the functioning of the dehesa. The Iberian dehesa has always been considered as a silvopastoral system where, at least, two strata of vegetation coexist: native grasses and trees. However the dehesa is also a diverse system where cropland and encroached territories have been systematically combined, more or less periodically, with native pasture in order to obtain agricultural, pastoral and forestry outputs. These multipurpose mosaic-type systems generate several scenarios where the plant influence zone may be overlapped and the interaction, competition or facilitation, between plants can play an important role in the ecosystem functioning in terms of productivity and stability. In the present study our aim was to characterize the rooting profile of multi-layered dehesas in order to understand the competitive, and/or facilitative, relationships within the different plant strata. The root profile of Quercus ilex subsp. ballota, Cistus ladanifer, Retama spaherocarpa and natural grasses was studied. So 48 trenches, up to 2 meters deep, were excavated in 4 different environments: (i) grass; (ii) tree-grass; (iii) tree-shrub and (iv) tree-shrub-grass (12 trenches in each environment). The study was carried out in 4 dehesas, 2 encroached with C. ladanifer and 2 with R. spaherocarpa. In every trench soil samples were taken each 20 cm. Subsequently, all samples were sieved using different mesh

  14. Establishment of Azotobacter on plant roots: chemotactic response, development and analysis of root exudates of cotton (Gossypium hirsutum L.) and wheat (Triticum aestivum L.).

    PubMed

    Kumar, Rakesh; Bhatia, Ranjana; Kukreja, K; Behl, Rishi Kumar; Dudeja, Surjit Singh; Narula, Neeru

    2007-10-01

    Biofertilizers contribute in N(2) fixation, P solubilization, phytohormone production and thus enhance plant growth. Beneficial plant-microbe interactions and the stability and effectiveness of biofertilizer depend upon the establishment of bacterial strains in the rhizosphere of the plant. This interaction depends upon many factors, one of them being plant exudates. Root exudates are composed of small organic molecules like carbonic acids, amino acids or sugars etc., which are released into the soil and bacteria can be attracted towards these exudates due to chemotaxis. The chemotactic behaviour of Azotobacter strains was studied using cotton (Desi HD 123 and American H 1098) and wheat (WH 711) seedlings and the root exudates of these two plants were chemically characterized. Analysis of the root exudates revealed the presence of sugars and simple polysaccharides (glucose), amino acids (glutamate, lysine) and organic acids (citric acid, succinic acid, maleic acid, malonic acid). Differences between cotton cultivars in root exudates were observed which influenced chemotactic response in Azotobacter. These results indicate colonization with rhizobacteria which implies that optimal symbionts, on the sides of both plant cultivar and bioinoculant bacteria can lead to better plant growth under cultivation conditions. PMID:17910096

  15. Root traits contributing to plant productivity under drought

    Technology Transfer Automated Retrieval System (TEKTRAN)

    ROOT TRAITS CONTRIBUTING TO PLANT PRODUCTIVITY UNDER DROUGHT L.H. Comas1, S.R. Becker2, V.M.V. Cruz3,4, P.F. Byrne2, D.A. Dierig3 1USDA-ARS, Water Management Research Unit, Fort Collins, CO, USA 2Colorado State University, Soil and Crop Sciences, Fort Collins, CO, USA 3USDA-ARS, National Center fo...

  16. Perception of neighboring plants by rhizomes and roots: morphological manifestations of a clonal plant

    USGS Publications Warehouse

    Huber-Sannwald, Elisabeth; Pyke, David A.; Caldwell, M.M.

    1997-01-01

    A previous study showed that clonal morphology of the rhizomatous grass Elymus lanceolatus ssp. lanceolatus (Scibner & J.G. Smith Gould) was influenced more by neighbouring root systems than by the local distribution of nutrients. In this study we determine whether individual rhizomes or roots of E. lanceolatus perceive neighbouring root systems and how this is manifested in morphological responses of E. lanceolatus clones. Elymus lanceolatus was grown in the same bin with Pseudoroegneria spicata (Pursh) A. Love or Agropyron desertorum (Fisch. ex Link) Schult. plants. Elymus lanceolatus was separated from its neighbours by different barriers. The barriers allowed either only E. lanceolatus roots; only a single E. lanceolatus primary rhizome; or both roots and rhizomes to contact the neighbour root system. When only a single E. lanceolatus primary rhizome with potentially developing branching rhizomes made contact with the neighbour, the clonal structure of E. lanceolatus was modified more with P. spicata as the neighbour than with A. desertorum. With root contact of E. lanceolatus alone there was a similar effect with the neighbouring plants, but there was a more marked inhibitory effect on E. lanceolatus clonal growth with P. spicata than with A. desertorum, compared with the treatment with only a single rhizome in contact with the neighbour. Root resource competition in the unconstrained treatment (roots and rhizomes) between neighbouring plant and E. lanceolatus was more apparent with A. desertorum than with P. spicata. This study is one of the first to document that rhizome and root contact of a clonal plant with its neighbours may induce different clonal responses depending on the species of neighbour.

  17. Topsoil drying combined with increased sulfur supply leads to enhanced aliphatic glucosinolates in Brassica juncea leaves and roots.

    PubMed

    Tong, Yu; Gabriel-Neumann, Elke; Ngwene, Benard; Krumbein, Angelika; George, Eckhard; Platz, Stefanie; Rohn, Sascha; Schreiner, Monika

    2014-01-01

    The decrease of water availability is leading to an urgent demand to reduce the plants' water supply. This study evaluates the effect of topsoil drying, combined with varying sulfur (S) supply on glucosinolates in Brassica juncea in order to reveal whether a partial root drying may already lead to a drought-induced glucosinolate increase promoted by an enhanced S supply. Without decreasing biomass, topsoil drying initiated an increase in aliphatic glucosinolates in leaves and in topsoil dried roots supported by increased S supply. Simultaneously, abscisic acid was determined, particularly in dehydrated roots, associated with an increased abscisic acid concentration in leaves under topsoil drying. This indicates that the dehydrated roots were the direct interface for the plants' stress response and that the drought-induced accumulation of aliphatic glucosinolates is related to abscisic acid formation. Indole and aromatic glucosinolates decreased, suggesting that these glucosinolates are less involved in the plants' response to drought. PMID:24444925

  18. Potential involvement of drought-induced Ran GTPase CLRan1 in root growth enhancement in a xerophyte wild watermelon.

    PubMed

    Akashi, Kinya; Yoshimura, Kazuya; Kajikawa, Masataka; Hanada, Kouhei; Kosaka, Rina; Kato, Atsushi; Katoh, Akira; Nanasato, Yoshihiko; Tsujimoto, Hisashi; Yokota, Akiho

    2016-10-01

    Enhanced root growth is known as the survival strategy of plants under drought. Previous proteome analysis in drought-resistant wild watermelon has shown that Ran GTPase, an essential regulator of cell division and proliferation, was induced in the roots under drought. In this study, two cDNAs were isolated from wild watermelon, CLRan1 and CLRan2, which showed a high degree of structural similarity with those of other plant Ran GTPases. Quantitative RT-PCR and promoter-GUS assays suggested that CLRan1 was expressed mainly in the root apex and lateral root primordia, whereas CLRan2 was more broadly expressed in other part of the roots. Immunoblotting analysis confirmed that the abundance of CLRan proteins was elevated in the root apex region under drought stress. Transgenic Arabidopsis overexpressing CLRan1 showed enhanced primary root growth, and the growth was maintained under osmotic stress, indicating that CLRan1 functions as a positive factor for maintaining root growth under stress conditions. PMID:27310473

  19. Tall fescue cultivar and fungal endophyte combinations influence plant growth and root exudate composition.

    PubMed

    Guo, Jingqi; McCulley, Rebecca L; McNear, David H

    2015-01-01

    Tall fescue [Lolium arundinaceum (Schreb.)] is a cool-season perennial grass used in pastures throughout the Southeastern United States. The grass can harbor a shoot-specific fungal endophyte (Epichloë coenophiala) thought to provide the plant with enhanced resistance to biotic and abiotic stresses. Because alkaloids produced by the common variety of the endophyte cause severe animal health issues, focus has been on replacing the common-toxic strain with novel varieties that do not produce the mammal-toxic alkaloids but maintain abiotic and biotic stress tolerance benefits. Little attention has been given to the influence of the plant-fungal symbiosis on rhizosphere processes. Therefore, our objective was to study the influence of this relationship on plant biomass production and root exudate composition in tall fescue cultivars PDF and 97TF1, which were either not infected with the endophyte (E-), infected with the common toxic endophyte (CTE+) strain or with one of two novel endophytes (AR542E+, AR584E+). Plants were grown sterile for 3 weeks after which plant biomass, total organic carbon, total phenolic content and detailed chemical composition of root exudates were determined. Plant biomass production and exudate phenolic and organic carbon content were influenced by endophyte status, tall fescue cultivar, and their interaction. GC-TOF MS identified 132 compounds, including lipids, carbohydrates and carboxylic acids. Cluster analysis showed that the interaction between endophyte and cultivar resulted in unique exudate profiles. This is the first detailed study to assess how endophyte infection, notably with novel endophytes, and tall fescue cultivar interact to influence root exudate composition. Our results illustrate that tall fescue cultivar and endophyte status can influence plant growth and root exudate composition, which may help explain the observed influence of this symbiosis on rhizosphere biogeochemical processes. PMID:25914697

  20. Tall fescue cultivar and fungal endophyte combinations influence plant growth and root exudate composition

    PubMed Central

    Guo, Jingqi; McCulley, Rebecca L.; McNear, David H.

    2015-01-01

    Tall fescue [Lolium arundinaceum (Schreb.)] is a cool-season perennial grass used in pastures throughout the Southeastern United States. The grass can harbor a shoot-specific fungal endophyte (Epichloë coenophiala) thought to provide the plant with enhanced resistance to biotic and abiotic stresses. Because alkaloids produced by the common variety of the endophyte cause severe animal health issues, focus has been on replacing the common-toxic strain with novel varieties that do not produce the mammal-toxic alkaloids but maintain abiotic and biotic stress tolerance benefits. Little attention has been given to the influence of the plant-fungal symbiosis on rhizosphere processes. Therefore, our objective was to study the influence of this relationship on plant biomass production and root exudate composition in tall fescue cultivars PDF and 97TF1, which were either not infected with the endophyte (E-), infected with the common toxic endophyte (CTE+) strain or with one of two novel endophytes (AR542E+, AR584E+). Plants were grown sterile for 3 weeks after which plant biomass, total organic carbon, total phenolic content and detailed chemical composition of root exudates were determined. Plant biomass production and exudate phenolic and organic carbon content were influenced by endophyte status, tall fescue cultivar, and their interaction. GC-TOF MS identified 132 compounds, including lipids, carbohydrates and carboxylic acids. Cluster analysis showed that the interaction between endophyte and cultivar resulted in unique exudate profiles. This is the first detailed study to assess how endophyte infection, notably with novel endophytes, and tall fescue cultivar interact to influence root exudate composition. Our results illustrate that tall fescue cultivar and endophyte status can influence plant growth and root exudate composition, which may help explain the observed influence of this symbiosis on rhizosphere biogeochemical processes. PMID:25914697

  1. Plant responses to atmospheric CO2 enrichment with emphasis on roots and the rhizosphere.

    PubMed

    Rogers, H H; Runion, G B; Krupa, S V

    1994-01-01

    (2). Root biomass is known to increase but, with few exceptions, detailed studies of root growth and function are lacking. Potential enhancement of root growth could translate into greater rhizodeposition, which, in turn, could lead to shifts in the rhizosphere itself. Some of the direct effects of CO(2) on vegetation have been reasonably well-studied, but for others work has been inadequate. Among these neglected areas are plant roots and the rhizosphere. Therefore, experiments on root and rhizosphere response in plants grown in CO(2)-enriched atmospheres will be reviewed and, where possible, collectively integrated. To this will be added data which have recently been collected by us. Having looked at the available data base, we will offer a series of hypotheses which we consider as priority targets for future research. PMID:15091762

  2. Fast-cycling unit of root turnover in perennial herbaceous plants in a cold temperate ecosystem

    PubMed Central

    Sun, Kai; Luke McCormack, M.; Li, Le; Ma, Zeqing; Guo, Dali

    2016-01-01

    Roots of perennial plants have both persistent portion and fast-cycling units represented by different levels of branching. In woody species, the distal nonwoody branch orders as a unit are born and die together relatively rapidly (within 1–2 years). However, whether the fast-cycling units also exist in perennial herbs is unknown. We monitored root demography of seven perennial herbs over two years in a cold temperate ecosystem and we classified the largest roots on the root collar or rhizome as basal roots, and associated finer laterals as secondary, tertiary and quaternary roots. Parallel to woody plants in which distal root orders form a fast-cycling module, basal root and its finer laterals also represent a fast-cycling module in herbaceous plants. Within this module, basal roots had a lifespan of 0.5–2 years and represented 62–87% of total root biomass, thus dominating annual root turnover (60%–81% of the total). Moreover, root traits including root length, tissue density, and biomass were useful predictors of root lifespan. We conclude that both herbaceous and woody plants have fast-cycling modular units and future studies identifying the fast-cycling module across plant species should allow better understanding of how root construction and turnover are linked to whole-plant strategies. PMID:26791578

  3. Fast-cycling unit of root turnover in perennial herbaceous plants in a cold temperate ecosystem

    NASA Astrophysics Data System (ADS)

    Sun, Kai; Luke McCormack, M.; Li, Le; Ma, Zeqing; Guo, Dali

    2016-01-01

    Roots of perennial plants have both persistent portion and fast-cycling units represented by different levels of branching. In woody species, the distal nonwoody branch orders as a unit are born and die together relatively rapidly (within 1-2 years). However, whether the fast-cycling units also exist in perennial herbs is unknown. We monitored root demography of seven perennial herbs over two years in a cold temperate ecosystem and we classified the largest roots on the root collar or rhizome as basal roots, and associated finer laterals as secondary, tertiary and quaternary roots. Parallel to woody plants in which distal root orders form a fast-cycling module, basal root and its finer laterals also represent a fast-cycling module in herbaceous plants. Within this module, basal roots had a lifespan of 0.5-2 years and represented 62-87% of total root biomass, thus dominating annual root turnover (60%-81% of the total). Moreover, root traits including root length, tissue density, and biomass were useful predictors of root lifespan. We conclude that both herbaceous and woody plants have fast-cycling modular units and future studies identifying the fast-cycling module across plant species should allow better understanding of how root construction and turnover are linked to whole-plant strategies.

  4. Transport of silicon from roots to panicles in plants

    PubMed Central

    MA, Jian Feng; YAMAJI, Naoki; MITANI-UENO, Namiki

    2011-01-01

    Silicon (Si) is the most abundant minerals in soil and exerts beneficial effects on plant growth by alleviating various stresses. The transport of Si from soil to the panicles is mediated by different transporters. Lsi1, belonging to a NIP group of the aquaporin family, is responsible for the uptake of Si from soil into the root cells in both dicots and monocots although its expression patterns and cellular localization differ with plant species. The subsequent transport of Si out of the root cells towards the stele is medicated by an active efflux transporter, Lsi2. Lsi1 and Lsi2 are polarly localized at the distal and proximal sides, respectively, of both exodermis and endodermis in rice root. Silicon in the xylem sap is presented in the form of monosilicic acid and is unloaded by Lsi6, a homolog of Lsi1 in rice. Lsi6 is also involved in the inter-vascular transfer of Si at the node, which is necessary for preferential Si distribution to the panicles. PMID:21785256

  5. Nitric Oxide Mediates Root K+/Na+ Balance in a Mangrove Plant, Kandelia obovata, by Enhancing the Expression of AKT1-Type K+ Channel and Na+/H+ Antiporter under High Salinity

    PubMed Central

    Wang, Wen-Hua; Hu, Wen-Jun; Simon, Martin; Xiao, Qiang; Chen, Juan; Liu, Ting-Wu; Liu, Xiang; Zheng, Hai-Lei

    2013-01-01

    It is well known that nitric oxide (NO) enhances salt tolerance of glycophytes. However, the effect of NO on modulating ionic balance in halophytes is not very clear. This study focuses on the role of NO in mediating K+/Na+ balance in a mangrove species, Kandelia obovata Sheue, Liu and Yong. We first analyzed the effects of sodium nitroprusside (SNP), an NO donor, on ion content and ion flux in the roots of K. obovata under high salinity. The results showed that 100 μM SNP significantly increased K+ content and Na+ efflux, but decreased Na+ content and K+ efflux. These effects of NO were reversed by specific NO synthesis inhibitor and scavenger, which confirmed the role of NO in retaining K+ and reducing Na+ in K. obovata roots. Using western-blot analysis, we found that NO increased the protein expression of plasma membrane (PM) H+-ATPase and vacuolar Na+/H+ antiporter, which were crucial proteins for ionic balance. To further clarify the molecular mechanism of NO-modulated K+/Na+ balance, partial cDNA fragments of inward-rectifying K+ channel, PM Na+/H+ antiporter, PM H+-ATPase, vacuolar Na+/H+ antiporter and vacuolar H+-ATPase subunit c were isolated. Results of quantitative real-time PCR showed that NO increased the relative expression levels of these genes, while this increase was blocked by NO synthesis inhibitors and scavenger. Above results indicate that NO greatly contribute to K+/Na+ balance in high salinity-treated K. obovata roots, by activating AKT1-type K+ channel and Na+/H+ antiporter, which are the critical components in K+/Na+ transport system. PMID:23977070

  6. Effects of partial root-zone irrigation on hydraulic conductivity in the soil-root system of maize plants.

    PubMed

    Hu, Tiantian; Kang, Shaozhong; Li, Fusheng; Zhang, Jianhua

    2011-08-01

    Effects of partial root-zone irrigation (PRI) on the hydraulic conductivity in the soil-root system (L(sr)) in different root zones were investigated using a pot experiment. Maize plants were raised in split-root containers and irrigated on both halves of the container (conventional irrigation, CI), on one side only (fixed PRI, FPRI), or alternately on one of two sides (alternate PRI, APRI). Results show that crop water consumption was significantly correlated with L(sr) in both the whole and irrigated root zones for all three irrigation methods but not with L(sr) in the non-irrigated root zone of FPRI. The total L(sr) in the irrigated root zone of two PRIs was increased by 49.0-92.0% compared with that in a half root zone of CI, suggesting that PRI has a significant compensatory effect of root water uptake. For CI, the contribution of L(sr) in a half root zone to L(sr) in the whole root zone was ∼50%. For FPRI, the L(sr) in the irrigated root zone was close to that of the whole root zone. As for APRI, the L(sr) in the irrigated root zone was greater than that of the non-irrigated root zone. In comparison, the L(sr) in the non-irrigated root zone of APRI was much higher than that in the dried zone of FPRI. The L(sr) in both the whole and irrigated root zones was linearly correlated with soil moisture in the irrigated root zone for all three irrigation methods. For the two PRI treatments, total water uptake by plants was largely determined by the soil water in the irrigated root zone. Nevertheless, the non-irrigated root zone under APRI also contributed to part of the total crop water uptake, but the continuously non-irrigated root zone under FPRI gradually ceased to contribute to crop water uptake, suggesting that it is the APRI that can make use of all the root system for water uptake, resulting in higher water use efficiency. PMID:21527627

  7. Effects of partial root-zone irrigation on hydraulic conductivity in the soil–root system of maize plants

    PubMed Central

    Hu, Tiantian; Kang, Shaozhong; Li, Fusheng; Zhang, Jianhua

    2011-01-01

    Effects of partial root-zone irrigation (PRI) on the hydraulic conductivity in the soil–root system (Lsr) in different root zones were investigated using a pot experiment. Maize plants were raised in split-root containers and irrigated on both halves of the container (conventional irrigation, CI), on one side only (fixed PRI, FPRI), or alternately on one of two sides (alternate PRI, APRI). Results show that crop water consumption was significantly correlated with Lsr in both the whole and irrigated root zones for all three irrigation methods but not with Lsr in the non-irrigated root zone of FPRI. The total Lsr in the irrigated root zone of two PRIs was increased by 49.0–92.0% compared with that in a half root zone of CI, suggesting that PRI has a significant compensatory effect of root water uptake. For CI, the contribution of Lsr in a half root zone to Lsr in the whole root zone was ∼50%. For FPRI, the Lsr in the irrigated root zone was close to that of the whole root zone. As for APRI, the Lsr in the irrigated root zone was greater than that of the non-irrigated root zone. In comparison, the Lsr in the non-irrigated root zone of APRI was much higher than that in the dried zone of FPRI. The Lsr in both the whole and irrigated root zones was linearly correlated with soil moisture in the irrigated root zone for all three irrigation methods. For the two PRI treatments, total water uptake by plants was largely determined by the soil water in the irrigated root zone. Nevertheless, the non-irrigated root zone under APRI also contributed to part of the total crop water uptake, but the continuously non-irrigated root zone under FPRI gradually ceased to contribute to crop water uptake, suggesting that it is the APRI that can make use of all the root system for water uptake, resulting in higher water use efficiency. PMID:21527627

  8. A root moisture sensor for plants in microgravity.

    PubMed

    Clark, G J; Neville, G E; Dreschel, T W

    1994-11-01

    Development of components for bioregenerative life-support systems is a vital step toward long-term space exploration. The culturing of plants in a microgravity environment may be optimized by the use of appropriate sensors and controllers. This paper describes a sensor developed for determining the amount of fluid (nutrient solution) available on the surface of a porous ceramic nutrient delivery substrate to the roots of conventional crop plants. The sensor is based on the change in thermal capacitance and thermal conductance near the surface as the moisture content changes. The sensor could be employed as a data acquisition and control sensor to support the automated monitoring of plants grown in a microgravity environment. PMID:11540184

  9. Plant Nutrition: Root Transporters on the Move1

    PubMed Central

    Zelazny, Enric; Vert, Grégory

    2014-01-01

    Nutrient and water uptake from the soil is essential for plant growth and development. In the root, absorption and radial transport of nutrients and water toward the vascular tissues is achieved by a battery of specialized transporters and channels. Modulating the amount and the localization of these membrane transport proteins appears as a way to drive their activity and is essential to maintain nutrient homeostasis in plants. This control first involves the delivery of newly synthesized proteins to the plasma membrane by establishing check points along the secretory pathway, especially during the export from the endoplasmic reticulum. Plasma membrane-localized transport proteins are internalized through endocytosis followed by recycling to the cell surface or targeting to the vacuole for degradation, hence constituting another layer of control. These intricate mechanisms are often regulated by nutrient availability, stresses, and endogenous cues, allowing plants to rapidly adjust to their environment and adapt their development. PMID:25034018

  10. Plant responses to heterogeneous salinity: growth of the halophyte Atriplex nummularia is determined by the root-weighted mean salinity of the root zone.

    PubMed

    Bazihizina, Nadia; Barrett-Lennard, Edward G; Colmer, Timothy D

    2012-11-01

    Soil salinity is generally spatially heterogeneous, but our understanding of halophyte physiology under such conditions is limited. The growth and physiology of the dicotyledonous halophyte Atriplex nummularia was evaluated in split-root experiments to test whether growth is determined by: (i) the lowest; (ii) the highest; or (iii) the mean salinity of the root zone. In two experiments, plants were grown with uniform salinities or horizontally heterogeneous salinities (10-450 mM NaCl in the low-salt side and 670 mM in the high-salt side, or 10 mM NaCl in the low-salt side and 500-1500 mM in the high-salt side). The combined data showed that growth and gas exchange parameters responded most closely to the root-weighted mean salinity rather than to the lowest, mean, or highest salinity in the root zone. In contrast, midday shoot water potentials were determined by the lowest salinity in the root zone, consistent with most water being taken from the least negative water potential source. With uniform salinity, maximum shoot growth was at 120-230 mM NaCl; ~90% of maximum growth occurred at 10 mM and 450 mM NaCl. Exposure of part of the roots to 1500 mM NaCl resulted in an enhanced (+40%) root growth on the low-salt side, which lowered root-weighted mean salinity and enabled the maintenance of shoot growth. Atriplex nummularia grew even with extreme salinity in part of the roots, as long as the root-weighted mean salinity of the root zone was within the 10-450 mM range. PMID:23125356

  11. Plant-in-chip: Microfluidic system for studying root growth and pathogenic interactions in Arabidopsis

    NASA Astrophysics Data System (ADS)

    Parashar, Archana; Pandey, Santosh

    2011-06-01

    We report a microfluidic platform for the hydroponic growth of Arabidopsis plants with high-resolution visualization of root development and root-pathogen interactions. The platform comprises a set of parallel microchannels with individual input/output ports where 1-day old germinated seedlings are initially placed. Under optimum conditions, a root system grows in each microchannel and its images are recorded over a 198-h period. Different concentrations of plant growth media show different root growth characteristics. Later, the developed roots are inoculated with two plant pathogens (nematodes and zoospores) and their physicochemical interactions with the live root systems are observed.

  12. Biosynthesis of Lipid Resorcinols and Benzoquinones in Isolated Secretory Plant Root Hairs

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The primary functions of root hairs are to increase the root surface area and to aid plants in water and nutrient uptake. However, some root hairs also have secretory functions and exude bioactive secondary metabolites. Sorghum bicolor root hairs release a substantial amount of the lipid benzoquin...

  13. The enhanced drought tolerance of rice plants under ammonium is related to aquaporin (AQP).

    PubMed

    Ding, Lei; Gao, Cuimin; Li, Yingrui; Li, Yong; Zhu, Yiyong; Xu, Guohua; Shen, Qirong; Kaldenhoff, Ralf; Kai, Lei; Guo, Shiwei

    2015-05-01

    Previously, we demonstrated that drought resistance in rice seedlings was increased by ammonium (NH4(+)) treatment, but not by nitrate (NO3(-)) treatment, and that the change was associated with root development. To study the effects of different forms of nitrogen on water uptake and root growth under drought conditions, we subjected two rice cultivars (cv. 'Shanyou 63' hybrid indica and cv. 'Yangdao 6' indica, China) to polyethylene glycol-induced drought stress in a glasshouse using hydroponic culture. Under drought conditions, NH4(+) significantly stimulated root growth compared to NO3(-), as indicated by the root length, surface area, volume, and numbers of lateral roots and root tips. Drought stress decreased the root elongation rate in both cultivars when they were supplied with NO3(-), while the rate was unaffected in the presence of NH4(+). Drought stress significantly increased root protoplast water permeability, root hydraulic conductivity, and the expression of root aquaporin (AQP) plasma intrinsic protein (PIP) genes in rice plants supplied with NH4(+); these changes were not observed in plants supplied with NO3(-). Additionally, ethylene, which is involved in the regulation of root growth, accumulated in rice roots supplied with NO3(-) under conditions of drought stress. We conclude that the increase in AQP expression and/or activity enhanced the root water uptake ability and the drought tolerance of rice plants supplied with NH4(+). PMID:25804805

  14. Community- Weighted Mean Plant Traits Predict Small Scale Distribution of Insect Root Herbivore Abundance

    PubMed Central

    Jeltsch, Florian; Wurst, Susanne

    2015-01-01

    Small scale distribution of insect root herbivores may promote plant species diversity by creating patches of different herbivore pressure. However, determinants of small scale distribution of insect root herbivores, and impact of land use intensity on their small scale distribution are largely unknown. We sampled insect root herbivores and measured vegetation parameters and soil water content along transects in grasslands of different management intensity in three regions in Germany. We calculated community-weighted mean plant traits to test whether the functional plant community composition determines the small scale distribution of insect root herbivores. To analyze spatial patterns in plant species and trait composition and insect root herbivore abundance we computed Mantel correlograms. Insect root herbivores mainly comprised click beetle (Coleoptera, Elateridae) larvae (43%) in the investigated grasslands. Total insect root herbivore numbers were positively related to community-weighted mean traits indicating high plant growth rates and biomass (specific leaf area, reproductive- and vegetative plant height), and negatively related to plant traits indicating poor tissue quality (leaf C/N ratio). Generalist Elaterid larvae, when analyzed independently, were also positively related to high plant growth rates and furthermore to root dry mass, but were not related to tissue quality. Insect root herbivore numbers were not related to plant cover, plant species richness and soil water content. Plant species composition and to a lesser extent plant trait composition displayed spatial autocorrelation, which was not influenced by land use intensity. Insect root herbivore abundance was not spatially autocorrelated. We conclude that in semi-natural grasslands with a high share of generalist insect root herbivores, insect root herbivores affiliate with large, fast growing plants, presumably because of availability of high quantities of food. Affiliation of insect root

  15. Community-Weighted Mean Plant Traits Predict Small Scale Distribution of Insect Root Herbivore Abundance.

    PubMed

    Sonnemann, Ilja; Pfestorf, Hans; Jeltsch, Florian; Wurst, Susanne

    2015-01-01

    Small scale distribution of insect root herbivores may promote plant species diversity by creating patches of different herbivore pressure. However, determinants of small scale distribution of insect root herbivores, and impact of land use intensity on their small scale distribution are largely unknown. We sampled insect root herbivores and measured vegetation parameters and soil water content along transects in grasslands of different management intensity in three regions in Germany. We calculated community-weighted mean plant traits to test whether the functional plant community composition determines the small scale distribution of insect root herbivores. To analyze spatial patterns in plant species and trait composition and insect root herbivore abundance we computed Mantel correlograms. Insect root herbivores mainly comprised click beetle (Coleoptera, Elateridae) larvae (43%) in the investigated grasslands. Total insect root herbivore numbers were positively related to community-weighted mean traits indicating high plant growth rates and biomass (specific leaf area, reproductive- and vegetative plant height), and negatively related to plant traits indicating poor tissue quality (leaf C/N ratio). Generalist Elaterid larvae, when analyzed independently, were also positively related to high plant growth rates and furthermore to root dry mass, but were not related to tissue quality. Insect root herbivore numbers were not related to plant cover, plant species richness and soil water content. Plant species composition and to a lesser extent plant trait composition displayed spatial autocorrelation, which was not influenced by land use intensity. Insect root herbivore abundance was not spatially autocorrelated. We conclude that in semi-natural grasslands with a high share of generalist insect root herbivores, insect root herbivores affiliate with large, fast growing plants, presumably because of availability of high quantities of food. Affiliation of insect root

  16. Root exudates of wetland plants influenced by nutrient status and types of plant cultivation.

    PubMed

    Wu, Fu Yong; Chung, Anna King Chuen; Tam, Nora Fung Yee; Wong, Ming Hung

    2012-07-01

    The present study investigated the amounts of root exudates and composition of organic acids released from two wetland plants (Typha latifolia and Vetiver zizanioides) under two nutrient treatments: low level (0.786 mM N and 0.032 mM P) and high level (7.86 mM N and 0.32 mM P) and two types of plant cultivation: monoculture and co-culture of the two plants. Low nutrient treatment significantly (p < 0.05) increased the root exudates of T. latifolia during the initial growth period (1-21 d) and those of V. zizanioides and the co-culture during the whole growth period. The concentrations of dissolved organic carbon in the root exudates of the co-culture in the low nutrient treatment were 3.23-7.91 times of those in the high nutrient treatment during the medium growth period (7-28 d). The compositions of organic acids varied between the two plant species and between the two nutrient treatments. The pattern of organic acids was also different between the co-culture and the monoculture. Oxalic acid was by far the major organic acid exuded from the two wetland plants. The present study on root exudates suggests that co-culture of wetland plant species would be more useful in the reclamation of waste water than a monoculture system. PMID:22908625

  17. Significance of Plant Root Microorganisms in Reclaiming Water in CELSS

    NASA Technical Reports Server (NTRS)

    Bubenheim, David L.; Greene, Catherine; Wignarajah, Kanapathipillai; Kliss, Mark H. (Technical Monitor)

    1996-01-01

    Since many microorganisms demonstrate the ability to quickly break down complex mixtures of waste and environmental contaminants, examining their potential use for water recycling in a closed environment is appealing. Water contributes approximately 90 percent of the life sustaining provisions in a human space habitat. Nearly half of the daily water requirements will be used for personal hygiene and dish washing. The primary contaminants of the used "gray" water will be the cleansing agents or soaps used to carry out these functions. Reclaiming water from the gray water waste streams is one goal of the NASA program, Controlled Ecological Life Support Systems (CELSS). The microorganisms of plane roots are well documented to be of a beneficial effect to promote plant growth. Most plants exhibit a range of bacteria and fungi which can be highly plant-specific. In our investigations with lettuce grown in hydroponic culture, we identified a microflora of normal rhizosphere. When the roots were exposed to an anionic surfactant, the species diversity changed, based on morphological characteristics, with the numbers of species being reduced from 7 to 2 after 48 hours of exposure. In addition, the species that became dominant in the presence of the anionic surfactant also demonstrated a dramatic increase in population density which corresponded to the degradation of the surfactant in the root zone. The potential for using these or other rhizosphere bacteria as a primary or secondary waste processor is promising, but a number of issues still warrant investigation; these include but are not limited to: (1) the full identification of the microbes, (2) the classes of surfactants the microbes will degrade, (3) the environmental conditions required for optimal processing efficiency and (4) the ability of transferring the microbes to a non-living solid matrix such as a bioreactor.

  18. Mesoscopic aspects of root water uptake modeling - Hydraulic resistances and root geometry interpretations in plant transpiration analysis

    NASA Astrophysics Data System (ADS)

    Vogel, Tomas; Votrubova, Jana; Dusek, Jaromir; Dohnal, Michal

    2016-02-01

    In the context of soil water flow modeling, root water uptake is often evaluated based on water potential difference between the soil and the plant (the water potential gradient approach). Root water uptake rate is modulated by hydraulic resistance of both the root itself, and the soil in the root vicinity. The soil hydraulic resistance is a function of actual soil water content and can be assessed assuming radial axisymmetric water flow toward a single root (at the mesoscopic scale). In the present study, three approximate solutions of mesoscopic root water uptake - finite difference approximation, steady-state solution, and steady-rate solution - are examined regarding their ability to capture the pressure head variations in the root vicinity. Insignificance of their differences when implemented in the macroscopic soil water flow model is demonstrated using the critical root water uptake concept. Subsequently, macroscopic simulations of coupled soil water flow and root water uptake are presented for a forest site under temperate humid climate. Predicted soil water pressure heads and actual transpiration rates are compared with observed data. Scenario simulations illustrate uncertainties associated with estimates of root geometrical and hydraulic properties. Regarding the actual transpiration prediction, the correct characterization of active root system geometry and hydraulic properties seems far more important than the choice of a particular mesoscopic model.

  19. Elicitation Based Enhancement of Secondary Metabolites in Rauwolfia serpentina and Solanum khasianum Hairy Root Cultures

    PubMed Central

    Srivastava, Mrinalini; Sharma, Swati; Misra, Pratibha

    2016-01-01

    Background: Rauwolfia serpentina and Solanum khasianum are well-known medicinally important plants contained important alkaloids in their different parts. Elicitation of these alkaloids is important because of associated pharmaceutical properties. Targeted metabolites were ajmaline and ajmalicine in R. serpentina; solasodine and α-solanine in S. khasianum. Objective: Enhancement of secondary metabolites through biotic and abiotic elicitors in hairy root cultures of R. serpentina and S. khasianum. Materials and Methods: In this report, hairy root cultures of these two plants were established through Agrobacterium rhizogenes mediated transformation by optimizing various parameters as age of explants, duration of preculture, and co-cultivation period. NaCl was used as abiotic elicitors in these two plants. Cellulase from Aspergillus niger was used as biotic elicitor in S. khasianum and mannan from Saccharomyces cerevisiae was used in R. serpentina. Results: First time we have reported the effect of biotic and abiotic elicitors on the production of important metabolites in hairy root cultures of these two plants. Ajmalicine production was stimulated up to 14.8-fold at 100 mM concentration of NaCl after 1 week of treatment. Ajmaline concentration was also increased 2.9-fold at 100 mg/l dose of mannan after 1 week. Solasodine content was enhanced up to 4.0-fold and 3.6-fold at 100 mM and 200 mM NaCl, respectively, after 6 days of treatments. Conclusion: This study explored the potential of the elicitation strategy in A. rhizogenes transformed cell cultures and this potential further used for commercial production of these pharmaceutically important secondary metabolites. SUMMARY Hairy roots of Rauwolfia serpentina were subjected to salt (abiotic stress) and mannan (biotic stress) treatment for 1 week. Ajmaline and ajmalicine secondary metabolites were quantified before and after stress treatmentAjmalicine yield was enhanced up to 14.8-fold at 100 mM concentration of Na

  20. Operational Evaluation of the Root Modules of the Advanced Plant Habitat

    NASA Technical Reports Server (NTRS)

    Monje, O.

    2014-01-01

    Photosynthetic and growth data were collected on APH Root Module. Described Stand pipe system for active moisture control. Tested germination in wicks. Evaluated EC-5 moisture sensors. Demonstrated that Wheat plants can grow in the APH Root Module.

  1. Could Uptake and Acropetal Translocation of PBDEs by Corn Be Enhanced Following Cu Exposure? Evidence from a Root Damage Experiment.

    PubMed

    Wang, Shaorui; Wang, Yan; Luo, Chunling; Jiang, Longfei; Song, Mengke; Zhang, Dayi; Wang, Yujie; Zhang, Gan

    2016-01-19

    Cocontamination by heavy metals and persistent organic pollutants (POPs) is ubiquitous in the environment. Fate of POPs within soil/water-plant system is a significant concern and an area where much uncertainty still exists when plants suffered cotoxicity from POPs and metals. This study investigated the fate of polybrominated diphenyl ethers (PBDEs) when copper (Cu) was present within the soil/water-plant system using pot and hydroponic experiments. The presence of Cu was found to induce damage to the root cell membranes of corn (Zea mays L. cv. Nongda 108) with increasing concentration in both shoots and roots. The PBDE congeners BDE209 and BDE47 in shoots were also enhanced with the increasing electrolytic leakage from root, attributed to Cu damage, and the highest shoot BDE209 and BDE47 levels were observed under the highest Cu dosage. In addition, positive correlations were observed between the PBDE content of corn shoots and the electrolytic leakage of corn roots. These results indicated that within a defective root system, more PBDEs will penetrate the roots and are acropetally translocated in the shoots. The potential ecological risk associated with the translocation and accumulation of POPs into plant shoots needs careful reconsideration in media cocontaminated with metals and POPs, whereas often ignored or underestimated in environmental risk assessments. PMID:26694851

  2. Arbuscular mycorrhizal symbiosis increases relative apoplastic water flow in roots of the host plant under both well-watered and drought stress conditions

    PubMed Central

    Bárzana, Gloria; Aroca, Ricardo; Paz, José Antonio; Chaumont, François; Martinez-Ballesta, Mari Carmen; Carvajal, Micaela; Ruiz-Lozano, Juan Manuel

    2012-01-01

    Background and Aims The movement of water through mycorrhizal fungal tissues and between the fungus and roots is little understood. It has been demonstrated that arbuscular mycorrhizal (AM) symbiosis regulates root hydraulic properties, including root hydraulic conductivity. However, it is not clear whether this effect is due to a regulation of root aquaporins (cell-to-cell pathway) or to enhanced apoplastic water flow. Here we measured the relative contributions of the apoplastic versus the cell-to-cell pathway for water movement in roots of AM and non-AM plants. Methods We used a combination of two experiments using the apoplastic tracer dye light green SF yellowish and sodium azide as an inhibitor of aquaporin activity. Plant water and physiological status, root hydraulic conductivity and apoplastic water flow were measured. Key Results Roots of AM plants enhanced significantly relative apoplastic water flow as compared with non-AM plants and this increase was evident under both well-watered and drought stress conditions. The presence of the AM fungus in the roots of the host plants was able to modulate the switching between apoplastic and cell-to-cell water transport pathways. Conclusions The ability of AM plants to switch between water transport pathways could allow a higher flexibility in the response of these plants to water shortage according to the demand from the shoot. PMID:22294476

  3. Release from belowground enemies and shifts in root traits as interrelated drivers of alien plant invasion success: a hypothesis.

    PubMed

    Dawson, Wayne

    2015-10-01

    Our understanding of the interrelated mechanisms driving plant invasions, such as the interplay between enemy release and resource-acquisition traits, is biased by an aboveground perspective. To address this bias, I hypothesize that plant release from belowground enemies (especially fungal pathogens) will give invasive plant species a fitness advantage in the alien range, via shifts in root traits (e.g., increased specific root length and branching intensity) that increase resource uptake and competitive ability compared to native species in the alien range, and compared to plants of the invader in its native range. Such root-trait changes could be ecological or evolutionary in nature. I explain how shifts in root traits could occur as a consequence of enemy release and contribute to invasion success of alien plants, and how they could be interrelated with other potential belowground drivers of invasion success (allelopathy, mutualist enhancement). Finally, I outline the approaches that could be taken to test whether belowground enemy release results in increased competitive ability and nutrient uptake by invasive alien plants, via changes in root traits in the alien range. PMID:26668717

  4. Plant roots and spectroscopic methods – analyzing species, biomass and vitality

    PubMed Central

    Rewald, Boris; Meinen, Catharina

    2013-01-01

    In order to understand plant functioning, plant community composition, and terrestrial biogeochemistry, it is decisive to study standing root biomass, (fine) root dynamics, and interactions belowground. While most plant taxa can be identified by visual criteria aboveground, roots show less distinctive features. Furthermore, root systems of neighboring plants are rarely spatially segregated; thus, most soil horizons and samples hold roots of more than one species necessitating root sorting according to taxa. In the last decades, various approaches, ranging from anatomical and morphological analyses to differences in chemical composition and DNA sequencing were applied to discern species’ identity and biomass belowground. Among those methods, a variety of spectroscopic methods was used to detect differences in the chemical composition of roots. In this review, spectroscopic methods used to study root systems of herbaceous and woody species in excised samples or in situ will be discussed. In detail, techniques will be reviewed according to their usability to discern root taxa, to determine root vitality, and to quantify root biomass non-destructively or in soil cores holding mixtures of plant roots. In addition, spectroscopic methods which may be able to play an increasing role in future studies on root biomass and related traits are highlighted. PMID:24130565

  5. The root endophyte fungus Piriformospora indica leads to early flowering, higher biomass and altered secondary metabolites of the medicinal plant, Coleus forskohlii

    PubMed Central

    Das, Aparajita; Kamal, Shwet; Shakil, Najam Akhtar; Sherameti, Irena; Oelmüller, Ralf; Dua, Meenakshi; Tuteja, Narendra; Johri, Atul Kumar; Varma, Ajit

    2012-01-01

    This study was undertaken to investigate the influence of plant probiotic fungus Piriformospora indica on the medicinal plant C. forskohlii. Interaction of the C. forskohlii with the root endophyte P. indica under field conditions, results in an overall increase in aerial biomass, chlorophyll contents and phosphorus acquisition. The fungus also promoted inflorescence development, consequently the amount of p-cymene in the inflorescence increased. Growth of the root thickness was reduced in P. indica treated plants as they became fibrous, but developed more lateral roots. Because of the smaller root biomass, the content of forskolin was decreased. The symbiotic interaction of C. forskohlii with P. indica under field conditions promoted biomass production of the aerial parts of the plant including flower development. The plant aerial parts are important source of metabolites for medicinal application. Therefore we suggest that the use of the root endophyte fungus P. indica in sustainable agriculture will enhance the medicinally important chemical production. PMID:22301976

  6. Where do roots take up water? Neutron radiography of water flow into the roots of transpiring plants growing in soil.

    PubMed

    Zarebanadkouki, Mohsen; Kim, Yangmin X; Carminati, Andrea

    2013-09-01

    Where and how fast does water flow from soil into roots? The answer to this question requires direct and in situ measurement of local flow of water into roots of transpiring plants growing in soil. We used neutron radiography to trace the transport of deuterated water (D₂O) in lupin (Lupinus albus) roots. Lupins were grown in aluminum containers (30 × 25 × 1 cm) filled with sandy soil. D₂O was injected in different soil regions and its transport in soil and roots was monitored by neutron radiography. The transport of water into roots was then quantified using a convection-diffusion model of D₂O transport into roots. The results showed that water uptake was not uniform along roots. Water uptake was higher in the upper soil layers than in the lower ones. Along an individual root, the radial flux was higher in the proximal segments than in the distal segments. In lupins, most of the water uptake occurred in lateral roots. The function of the taproot was to collect water from laterals and transport it to the shoot. This function is ensured by a low radial conductivity and a high axial conductivity. Lupin root architecture seems well designed to take up water from deep soil layers. PMID:23692148

  7. A Novel Interaction between Plant-Beneficial Rhizobacteria and Roots: Colonization Induces Corn Resistance against the Root Herbivore Diabrotica speciosa

    PubMed Central

    Santos, Franciele; Peñaflor, Maria Fernanda G. V.; Paré, Paul W.; Sanches, Patrícia A.; Kamiya, Aline C.; Tonelli, Mateus; Nardi, Cristiane; Bento, José Mauricio S.

    2014-01-01

    A number of soil-borne microorganisms, such as mycorrhizal fungi and rhizobacteria, establish mutualistic interactions with plants, which can indirectly affect other organisms. Knowledge of the plant-mediated effects of mutualistic microorganisms is limited to aboveground insects, whereas there is little understanding of what role beneficial soil bacteria may play in plant defense against root herbivory. Here, we establish that colonization by the beneficial rhizobacterium Azospirillum brasilense affects the host selection and performance of the insect Diabrotica speciosa. Root larvae preferentially orient toward the roots of non-inoculated plants versus inoculated roots and gain less weight when feeding on inoculated plants. As inoculation by A. brasilense induces higher emissions of (E)-β-caryophyllene compared with non-inoculated plants, it is plausible that the non-preference of D. speciosa for inoculated plants is related to this sesquiterpene, which is well known to mediate belowground insect-plant interactions. To the best of our knowledge, this is the first study showing that a beneficial rhizobacterium inoculant indirectly alters belowground plant-insect interactions. The role of A. brasilense as part of an integrative pest management (IPM) program for the protection of corn against the South American corn rootworm, D. speciosa, is considered. PMID:25405495

  8. Low crown root number enhances nitrogen acquisition from low-nitrogen soils in maize.

    PubMed

    Saengwilai, Patompong; Tian, Xiaoli; Lynch, Jonathan Paul

    2014-10-01

    In developing nations, low soil nitrogen (N) availability is a primary limitation to crop production and food security, while in rich nations, intensive N fertilization is a primary economic, energy, and environmental cost to crop production. It has been proposed that genetic variation for root architectural and anatomical traits enhancing the exploitation of deep soil strata could be deployed to develop crops with greater N acquisition. Here, we provide evidence that maize (Zea mays) genotypes with few crown roots (crown root number [CN]) have greater N acquisition from low-N soils. Maize genotypes differed in their CN response to N limitation in greenhouse mesocosms and in the field. Low-CN genotypes had 45% greater rooting depth in low-N soils than high-CN genotypes. Deep injection of (15)N-labeled nitrate showed that low-CN genotypes under low-N conditions acquired more N from deep soil strata than high-CN genotypes, resulting in greater photosynthesis and plant N content. Under low N, low-CN genotypes had greater biomass than high-CN genotypes at flowering (85% in the field study in the United States and 25% in South Africa). In the field in the United States, 1.8× variation in CN was associated with 1.8× variation in yield reduction by N limitation. Our results indicate that CN deserves consideration as a potential trait for genetic improvement of N acquisition from low-N soils. PMID:24706553

  9. Aquatic adventitious root development in partially and completely submerged wetland plants Cotula coronopifolia and Meionectes brownii

    PubMed Central

    Rich, Sarah Meghan; Ludwig, Martha; Colmer, Timothy David

    2012-01-01

    Background and Aims A common response of wetland plants to flooding is the formation of aquatic adventitious roots. Observations of aquatic root growth are widespread; however, controlled studies of aquatic roots of terrestrial herbaceous species are scarce. Submergence tolerance and aquatic root growth and physiology were evaluated in two herbaceous, perennial wetland species Cotula coronopifolia and Meionectes brownii. Methods Plants were raised in large pots with ‘sediment’ roots in nutrient solution and then placed into individual tanks and shoots were left in air or submerged (completely or partially). The effects on growth of aquatic root removal, and of light availability to submerged plant organs, were evaluated. Responses of aquatic root porosity, chlorophyll and underwater photosynthesis, were studied. Key Results Both species tolerated 4 weeks of complete or partial submergence. Extensive, photosynthetically active, aquatic adventitious roots grew from submerged stems and contributed up to 90 % of the total root dry mass. When aquatic roots were pruned, completely submerged plants grew less and had lower stem and leaf chlorophyll a, as compared with controls with intact roots. Roots exposed to the lowest PAR (daily mean 4·7 ± 2·4 µmol m−2 s−1) under water contained less chlorophyll, but there was no difference in aquatic root biomass after 4 weeks, regardless of light availability in the water column (high PAR was available to all emergent shoots). Conclusions Both M. brownii and C. coronopifolia responded to submergence with growth of aquatic adventitious roots, which essentially replaced the existing sediment root system. These aquatic roots contained chlorophyll and were photosynthetically active. Removal of aquatic roots had negative effects on plant growth during partial and complete submergence. PMID:22419759

  10. Spinal Nerve Root Enhancement on MRI Scans in Children: A Review.

    PubMed

    Kontzialis, Marinos; Poretti, Andrea; Michell, Hans; Bosemani, Thangamadhan; Tekes, Aylin; Huisman, Thierry A G M

    2016-01-01

    Spinal nerve root enhancement in pediatric patients is generally nonspecific, and clinical and laboratory correlation is essential. Nerve root enhancement indicates lack of integrity of the blood-nerve barrier. In this review, we will present a range of pediatric conditions that can present with spinal nerve root enhancement including inflammatory, infectious, hereditary, and neoplastic causes. Familiarity with the various pathologic entities associated with spinal nerve root enhancement is important for a concise differential diagnosis in the appropriate clinical setting. This will avoid unnecessary additional investigations. PMID:26365273

  11. Neighbor influences on root morphology and mycorrhizal fungus colonization in tallgrass prairie plants

    SciTech Connect

    Jastrow, J.D. Univ. of Illinois, Chicago ); Miller, R.M. )

    1993-03-01

    A field study was conducted across a chronosequence of tallgrass prairie restorations to investigate the influence a plant's neighbor may have on its gross root morphology and association with mycorrhizal fungi. The root systems of a warm-season grass, Andropogon gerardii, and two perennial forbs, Coreopsis tripteris and Solidago altissima, were sampled by excavating soil blocks representing all pairwise inter- and intra-specific combinations of these species. With forb neighbors, Andropogon had higher percentages of its firbrous roots colonized by mycorrhizal fungi than with conspecific neighbors. Andropogon root morphology (as measured by average root radius, specific root length, and root branching) did not vary with neighbor growth form; however, Andropogon roots did become finer as restoration age and root densities increased. For Coreopsis and Solidago, colonization of fibrous roots did not vary with neighbor species, but both forbs had coarser roots with interspecific neighbors than with conspecifics. With interspecific neighbors, Coreopsis almost doubled the number of branches per centimetre of root observed in conspecific pairs. Although some of the variations in colonization and root morphology may be attributable specifically to neighbor root mass, others were related to the overall root mass of the target-neighbor pair. The observed variations in mycorrhizal colonization may be related to increased opportunities for colonization by the fungus that are due not only to higher root densities but also to some sort of interaction between the root systems of Andropogon and the forbs. 44 refs., 2 figs., 2 tabs.

  12. Root Exudate-Induced Alterations in Bacillus cereus Cell Wall Contribute to Root Colonization and Plant Growth Promotion

    PubMed Central

    Dutta, Swarnalee; Rani, T. Swaroopa; Podile, Appa Rao

    2013-01-01

    The outcome of an interaction between plant growth promoting rhizobacteria and plants may depend on the chemical composition of root exudates (REs). We report the colonization of tobacco, and not groundnut, roots by a non-rhizospheric Bacillus cereus (MTCC 430). There was a differential alteration in the cell wall components of B. cereus in response to the REs from tobacco and groundnut. Attenuated total reflectance infrared spectroscopy revealed a split in amide I region of B. cereus cells exposed to tobacco-root exudates (TRE), compared to those exposed to groundnut-root exudates (GRE). In addition, changes in exopolysaccharides and lipid-packing were observed in B. cereus grown in TRE-amended minimal media that were not detectable in GRE-amended media. Cell-wall proteome analyses revealed upregulation of oxidative stress-related alkyl hydroperoxide reductase, and DNA-protecting protein chain (Dlp-2), in response to GRE and TRE, respectively. Metabolism-related enzymes like 2-amino-3-ketobutyrate coenzyme A ligase and 2-methylcitrate dehydratase and a 60 kDa chaperonin were up-regulated in response to TRE and GRE. In response to B. cereus, the plant roots altered their exudate-chemodiversity with respect to carbohydrates, organic acids, alkanes, and polyols. TRE-induced changes in surface components of B. cereus may contribute to successful root colonization and subsequent plant growth promotion. PMID:24205213

  13. Fate of polycyclic aromatic hydrocarbons in plant-soil systems: Plant responses to a chemical stress in the root zone

    SciTech Connect

    Hoylman, A.M.

    1993-01-01

    Plant uptake and translocation of polycyclic aromatic hydrocarbons (PAHs) from soil was investigated to explore plant-microbial interactions in response to a chemical stress in the root zone. Plant uptake of individual PAHs was examined under laboratory conditions which maximized root exposure. White sweetclover, Melilotus alba, was grown in soils dosed with [sup 14]C-naphthalene, -phenanthrene, -pyrene, and -fluoranthene. The highest [sup 14]C concentrations were associated with roots, with decreasing concentrations observed in stems and leaves; however, the greatest percentage of recoverable [sup 14]C remained in the soil ([ge]86%) for all four PAHs. No evidence of bioaccumulation of the individual PAHs was found in M. alba over a 5-day exposure period. Root uptake and translocation of PAHs from soil to aboveground plant tissues proved to be a limited mechanism for PAH transport into terrestrial food chains. However, root surface sorption of PAHs may be important for plants in soils containing elevated concentrations of PAHs. Consequently, the root-soil interface may be important for plant-microbial interactions in response to a chemical stress. [sup 14]CO[sub 2] pulse-labeling studies provide evidence of a shift in [sup 14]C-allocation from aboveground tissue to the root zone when plants were exposed simultaneously to phenanthrene in soil. In addition, soil respiration and heterotrophic plate counts of rhizosphere microorganisms increased in plants exposed to phenanthrene as compared to controls. This study demonstrates the importance of the root-soil interface for plants growing in PAH contaminated soil and provides supportive evidence for a plant-microbial defense response to chemical toxicants in the root zone. Lipophilic toxicants in soils may reach high concentrations in the root zone, but rhizosphere microbial communities under the influence of the plant may reduce the amount of the compound that is actually taken up by the root.

  14. Microbial Population and Community Dynamics on Plant Roots and Their Feedbacks on Plant Communities

    PubMed Central

    Bever, James D.; Platt, Thomas G.; Morton, Elise R.

    2012-01-01

    The composition of the soil microbial community can be altered dramatically due to association with individual plant species, and these effects on the microbial community can have important feedbacks on plant ecology. Negative plant-soil feedback plays primary roles in maintaining plant community diversity, whereas positive plant-soil feedback may cause community conversion. Host-specific differentiation of the microbial community results from the trade-offs associated with overcoming plant defense and the specific benefits associated with plant rewards. Accumulation of host-specific pathogens likely generates negative feedback on the plant, while changes in the density of microbial mutualists likely generate positive feedback. However, the competitive dynamics among microbes depends on the multidimensional costs of virulence and mutualism, the fine-scale spatial structure within plant roots, and active plant allocation and localized defense. Because of this, incorporating a full view of microbial dynamics is essential to explaining the dynamics of plant-soil feedbacks and therefore plant community ecology. PMID:22726216

  15. The Influence of Plant Root Systems on Subsurface Flow: Implications for Slope Stability

    EPA Science Inventory

    Although research has explained how plant roots mechanically stabilize soils, in this article we explore how root systems create networks of preferential flow and thus influence water pressures in soils to trigger landslides. Root systems may alter subsurface flow: Hydrological m...

  16. Plant and root endophyte assembly history: interactive effects on native and exotic plants.

    PubMed

    Sikes, Benjamin A; Hawkes, Christine V; Fukami, Tadashi

    2016-02-01

    Differences in the arrival timing of plants and soil biota may result in different plant communities through priority effects, potentially affecting the success of native vs. exotic plants, but experimental evidence is largely lacking. We conducted a greenhouse experiment to investigate whether the assembly history of plants and fungal root endophytes could interact to influence plant emergence and biomass. We introduced a grass species and eight fungal species from one of three land-use types (undisturbed, disturbed, or pasture sites in a Florida scrubland) in factorial combinations. We then introduced all plants and fungi from the other land-use types 2 weeks later. Plant emergence was monitored for 6 months, and final plant biomass and fungal species composition assessed. The emergence and growth of the exotic Melinis repens and the native Schizacharyium niveum were affected negatively when introduced early with their "home" fungi, but early introduction of a different plant species or fungi from a different site type eliminated these negative effects, providing evidence for interactive priority effects. Interactive effects of plant and fungal arrival history may be an overlooked determinant of plant community structure and may provide an effective management tool to inhibit biological invasion and aid ecosystem restoration. PMID:27145622

  17. A fungal endophyte helps plants to tolerate root herbivory through changes in gibberellin and jasmonate signaling.

    PubMed

    Cosme, Marco; Lu, Jing; Erb, Matthias; Stout, Michael Joseph; Franken, Philipp; Wurst, Susanne

    2016-08-01

    Plant-microbe mutualisms can improve plant defense, but the impact of root endophytes on below-ground herbivore interactions remains unknown. We investigated the effects of the root endophyte Piriformospora indica on interactions between rice (Oryza sativa) plants and its root herbivore rice water weevil (RWW; Lissorhoptrus oryzophilus), and how plant jasmonic acid (JA) and GA regulate this tripartite interaction. Glasshouse experiments with wild-type rice and coi1-18 and Eui1-OX mutants combined with nutrient, jasmonate and gene expression analyses were used to test: whether RWW adult herbivory above ground influences subsequent damage caused by larval herbivory below ground; whether P. indica protects plants against RWW; and whether GA and JA signaling mediate these interactions. The endophyte induced plant tolerance to root herbivory. RWW adults and larvae acted synergistically via JA signaling to reduce root growth, while endophyte-elicited GA biosynthesis suppressed the herbivore-induced JA in roots and recovered plant growth. Our study shows for the first time the impact of a root endophyte on plant defense against below-ground herbivores, adds to growing evidence that induced tolerance may be an important root defense, and implicates GA as a signal component of inducible plant tolerance against biotic stress. PMID:27061745

  18. Arguments for and against self and non-self root recognition in plants

    PubMed Central

    Depuydt, Stephen

    2014-01-01

    Root–root interaction research gained more and more attention over the past few years. Roots are pivotal for plant survival because they ensure uptake of water and nutrients. Therefore, detection of adjacent roots might lead to competitive advantages. Several lines of experimental evidence suggest that roots have ways to discriminate non-related roots, kin, and—importantly—that they can sense self/non-self roots to avoid intra-plant competition. In this mini-review, the existence of self/non-self recognition in plant roots will be discussed and the current knowledge on the mechanisms that could be involved will be summarized. Although the process of identity recognition is still not completely understood, interesting data are available and emerging new technologies will certainly aid to better understand this research field that can have an important biological, ecological, and agricultural impact. PMID:25414719

  19. Root-synthesized cytokinins improve shoot growth and fruit yield in salinized tomato (Solanum lycopersicum L.) plants

    PubMed Central

    Ghanem, Michel Edmond; Smigocki, Ann C.; Frébort, Ivo; Pospíšilová, Hana; Martínez-Andújar, Cristina; Acosta, Manuel; Sánchez-Bravo, José; Lutts, Stanley; Dodd, Ian C.; Pérez-Alfocea, Francisco

    2011-01-01

    Salinity limits crop productivity, in part by decreasing shoot concentrations of the growth-promoting and senescence-delaying hormones cytokinins. Since constitutive cytokinin overproduction may have pleiotropic effects on plant development, two approaches assessed whether specific root-localized transgenic IPT (a key enzyme for cytokinin biosynthesis) gene expression could substantially improve tomato plant growth and yield under salinity: transient root IPT induction (HSP70::IPT) and grafting wild-type (WT) shoots onto a constitutive IPT-expressing rootstock (WT/35S::IPT). Transient root IPT induction increased root, xylem sap, and leaf bioactive cytokinin concentrations 2- to 3-fold without shoot IPT gene expression. Although IPT induction reduced root biomass (by 15%) in control (non-salinized) plants, in salinized plants (100 mM NaCl for 22 d), increased cytokinin concentrations delayed stomatal closure and leaf senescence and almost doubled shoot growth (compared with WT plants), with concomitant increases in the essential nutrient K+ (20%) and decreases in the toxic ion Na+ (by 30%) and abscisic acid (by 20–40%) concentrations in transpiring mature leaves. Similarly, WT/35S::IPT plants (scion/rootstock) grown with 75 mM NaCl for 90 d had higher fruit trans-zeatin concentrations (1.5- to 2-fold) and yielded 30% more than WT/non-transformed plants. Enhancing root cytokinin synthesis modified both shoot hormonal and ionic status, thus ameliorating salinity-induced decreases in growth and yield. PMID:20959628

  20. Ethylene Upregulates Auxin Biosynthesis in Arabidopsis Seedlings to Enhance Inhibition of Root Cell Elongation[W

    PubMed Central

    Swarup, Ranjan; Perry, Paula; Hagenbeek, Dik; Van Der Straeten, Dominique; Beemster, Gerrit T.S.; Sandberg, Göran; Bhalerao, Rishikesh; Ljung, Karin; Bennett, Malcolm J.

    2007-01-01

    Ethylene represents an important regulatory signal for root development. Genetic studies in Arabidopsis thaliana have demonstrated that ethylene inhibition of root growth involves another hormone signal, auxin. This study investigated why auxin was required by ethylene to regulate root growth. We initially observed that ethylene positively controls auxin biosynthesis in the root apex. We subsequently demonstrated that ethylene-regulated root growth is dependent on (1) the transport of auxin from the root apex via the lateral root cap and (2) auxin responses occurring in multiple elongation zone tissues. Detailed growth studies revealed that the ability of the ethylene precursor 1-aminocyclopropane-1-carboxylic acid to inhibit root cell elongation was significantly enhanced in the presence of auxin. We conclude that by upregulating auxin biosynthesis, ethylene facilitates its ability to inhibit root cell expansion. PMID:17630275

  1. Nitrogen Dynamics in the Soil-Root-Plant Continuum: Competitive and Mutualistic Dependencies through Hydraulic Redistribution

    NASA Astrophysics Data System (ADS)

    Quijano, J. C.; Kumar, P.; Drewry, D. T.

    2011-12-01

    Below ground processes occurring in natural ecosystems such as root water uptake and hydraulic redistribution (HR) have significant influence on the water dynamics. However, the real implications of these processes in the cycling of biogeochemical elements as N or P remain unknown. HR is a process by which plant roots are able to transport water passively in the soil column. Due to the capacity of HR to influence soil moisture and soil temperature it is believed that the presence of HR influences the rates of mineralization and ion diffusion in the soil enhancing nutrient uptake by plants. Furthermore, there is experimental evidence that HR enhances the interaction between species by facilitation of water from deeper to shallow rooted plants. Thus HR could also influence plant nutrient uptake in some species by facilitating a pathway from other species. In this study we use a numerical model to analyze the effects of HR on the N dynamics in the soil. We examine the effect of HR in decomposition of organic matter and passive transport of nitrogen in the soil column including plant uptake and leaching. We analyze the dynamics under two different cases of species composition (single or multiple species) to understand the nitrogen cycling in the presence of multiple plant species that coexist and the capacity of HR to enhance these dynamics. The model used in this study is multi species MLCan which is a multi-layer above- and below-ground soil-root-canopy model that is able to simulate species interaction using a "shared resource" conceptualization. MLCan is coupled with a C:N model (1) where only two pools of soil carbon, namely soil organic matter and microorganisms, are considered and soil N dynamics are calculated based on C:N ratio formulations. The forcing data is obtained from the Ameriflux Tower located in Blodgett Forest, Sierra Nevada, California. Three plant species are considered. We found that HR enhances the mineralization of organic matter at the surface

  2. Induced root-secreted phenolic compounds as a belowground plant defense.

    PubMed

    Lanoue, Arnaud; Burlat, Vincent; Schurr, Ulrich; Röse, Ursula S R

    2010-08-01

    Rhizosphere is the complex place of numerous interactions between plant roots, microbes and soil fauna. Whereas plant interactions with aboveground organisms are largely described, unravelling plant belowground interactions remains challenging. Plant root chemical communication can lead to positive interactions with nodulating bacteria, mycorriza or biocontrol agents or to negative interactions with pathogens or root herbivores. A recent study suggested that root exudates contribute to plant pathogen resistance via secretion of antimicrobial compounds. These findings point to the importance of plant root exudates as belowground signalling molecules, particularly in defence responses. In our report, we showed that under Fusarium attack the barley root system launched secretion of phenolic compounds with antimicrobial activity. The secretion of de novo biosynthesized t-cinnamic acid induced within 2 days illustrates the dynamic of plant defense mechanisms at the root level. We discuss the costs and benefits of induced defense responses in the rhizosphere. We suggest that plant defence through root exudation may be cultivar dependent and higher in wild or less domesticated varieties. PMID:20699651

  3. Adventitious Root Formation of Forest Trees and Horticultural Plants - From Genes to Applications

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Adventitious root formation is a key step in the clonal propagation of forest trees and horticultural crops. Difficulties in forming adventitious roots (ARs) on stem cuttings and plants produced in vitro hinders the propagation of elite trees and efficient production of many horticultural plant spec...

  4. Silicon enhanced salt tolerance by improving the root water uptake and decreasing the ion toxicity in cucumber

    PubMed Central

    Wang, Shiwen; Liu, Peng; Chen, Daoqian; Yin, Lina; Li, Hongbing; Deng, Xiping

    2015-01-01

    Although the effects of silicon application on enhancing plant salt tolerance have been widely investigated, the underlying mechanism has remained unclear. In this study, seedlings of cucumber, a medium silicon accumulator plant, grown in 0.83 mM silicon solution for 2 weeks were exposed to 65 mM NaCl solution for another 1 week. The dry weight and shoot/root ratio were reduced by salt stress, but silicon application significantly alleviated these decreases. The chlorophyll concentration, net photosynthetic rate, transpiration rate and leaf water content were higher in plants treated with silicon than in untreated plants under salt stress conditions. Further investigation showed that salt stress decreased root hydraulic conductance (Lp), but that silicon application moderated this salt-induced decrease in Lp. The higher Lp in silicon-treated plants may account for the superior plant water balance. Moreover, silicon application significantly decreased Na+ concentration in the leaves while increasing K+ concentration. Simultaneously, both free and conjugated types of polyamines were maintained at high levels in silicon-treated plants, suggesting that polyamines may be involved in the ion toxicity. Our results indicate that silicon enhances the salt tolerance of cucumber through improving plant water balance by increasing the Lp and reducing Na+ content by increasing polyamine accumulation. PMID:26442072

  5. Rooting out Defense Mechanisms in Wheat against Plant Parasitic Nematodes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Root-lesion nematodes (Pratylenchus spp.) are soil borne pathogens of many important agricultural crops including wheat. Pratylenchus invade root cells and feed using a stylet, resulting in cell death. Common signs of Pratylenchus damage are root lesions, girdling, and lack of lateral branching. ...

  6. Root and bacterial secretions regulate the interaction between plants and PGPR leading to distinct plant growth promotion effects

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Plant growth-promoting rhizobacteria (PGPR) have garnered interest in agriculture due to their ability to influence the growth and production of host plants. ATP-binding cassette (ABC) transporters play important roles in plant-microbe interactions by modulating plant root exudation. The present stu...

  7. Identification of QTLs associated with seedling root traits and their correlation with plant height in wheat.

    PubMed

    Bai, Caihong; Liang, Yinli; Hawkesford, Malcolm J

    2013-04-01

    Genetic relationships between plant height and root morphology were investigated in a diverse set of wheat germplasm [199 double-haploid progeny derived from a cross between Avalon and Cadenza (Triticum aestivum L.), Rht near-isogenic lines (NILs), and accessions from the Watkins Collection] to investigate whether Rht genes controlling shoot height also control seedling root growth. A germination paper screen was developed to measure seedling root length (distinguishing seminal axes from seminal lateral roots), surface area, volume, and dry weight, and these were compared with shoot dry weight and the root to shoot ratio. Field experiments were conducted to measure mature plant height (PH) and grain characteristics for the mapping population. Forty-three quantitative trait loci (QTLs) for PH, root and seed traits were identified. Some QTLs for roots and either height or seed characteristics were coincident: chromosome 2D had co-locating root and PH QTLs; chromosomes 4D had co-locating root, PH, and seed QTLs; chromosome 5A and 6A had co-locating root and seed QTLs; and other non-co-locating root and PH QTLs were found on chromosomes 3A and 3B. Rht NILs illustrated that some known dwarfing genes reduce both PH and root proliferation. However, analysis of 25 short and 23 tall lines from the Watkins wheat germplasm collection indicated that PH and root proliferation are not simply related. PMID:23564959

  8. Vesicular-arbuscular mycorrhizae and the enzymatic utilization of inorganic phosphate by plant roots: Progress report 1985

    SciTech Connect

    Marx, D. H.

    1985-01-01

    It is well known that phosphorus absorption, especially from soil with low phosphorus levels, by plant roots can be enhanced by mycorrhizal infection. Root cortical cells colonized by vesicular-arbuscular mycorrhizal fungi (VAM) have higher concentrations of phosphorus than noninfected cells. Polyphosphate is the major phosphorus reserve in many fungi and is reported to be present abundantly in young and proliferating arbuscules. We propose that mycorrhizal polyphosphate can be utilized by the VAM-plant symbiont system as a phosphorus donor and an energy source in the glycolytic pathway, possibly after being hydrolyzed to pytrophosphate (PPi). The VAM systems of infected and noninfected roots of sweetgum (Liquidambar styraciflua L.) and onion (Allium cepa L. var. Texas Grand) were used to compare the activity of PPI-dependent phosphofructokinase (PFK), an enzyme utilizing PPi to convert frutose-6-phosphate into fructosel,6-bisphosphate. The ATP-PKF activity was measured also. 1 fig., 3 tabs.

  9. Bacillus pumilus ES4: candidate plant growth-promoting bacterium to enhance establishment of plants in mine tailings

    PubMed Central

    de-Bashan, Luz E.; Hernandez, Juan-Pablo; Bashan, Yoav; Maier, Raina

    2014-01-01

    Three plant growth-promoting bacteria (PGPB; Bacillus pumilus ES4, B. pumilus RIZO1, and Azospirillum brasilense Cd) were tested for their ability to enhance plant growth and development of the native Sonoran Desert shrub quailbush (Atriplex lentiformis) and for their effect on the native bacterial community in moderately acidic, high-metal content (AHMT) and in neutral, low metal content natural tailings (NLMT) in controlled greenhouse experiments. Inoculation of quailbush with all three PGPB significantly enhanced plant growth parameters, such as germination, root length, dry weight of shoots and roots, and root/shoot ratio in both types of tailings. The effect of inoculation on the indigenous bacterial community by the most successful PGPB Bacillus pumilus ES4 was evaluated by denaturating gradient gel electrophoresis (PCR-DGGE) fingerprinting and root colonization was followed by specific fluorescent in situ hybridization (FISH). Inoculation with this strain significantly changed the bacterial community over a period of 60 days. FISH analysis showed that the preferred site of colonization was the root tips and root elongation area. This study shows that inoculation of native perennial plants with PGPB can be used for developing technologies for phytostabilizing mine tailings. PMID:25009362

  10. Root Herbivores Drive Changes to Plant Primary Chemistry, but Root Loss Is Mitigated under Elevated Atmospheric CO2.

    PubMed

    McKenzie, Scott W; Johnson, Scott N; Jones, T Hefin; Ostle, Nick J; Hails, Rosemary S; Vanbergen, Adam J

    2016-01-01

    Above- and belowground herbivory represents a major challenge to crop productivity and sustainable agriculture worldwide. How this threat from multiple herbivore pests will change under anthropogenic climate change, via altered trophic interactions and plant response traits, is key to understanding future crop resistance to herbivory. In this study, we hypothesized that atmospheric carbon enrichment would increase the amount (biomass) and quality (C:N ratio) of crop plant resources for above- and belowground herbivore species. In a controlled environment facility, we conducted a microcosm experiment using the large raspberry aphid (Amphorophora idaei), the root feeding larvae of the vine weevil (Otiorhynchus sulcatus), and the raspberry (Rubus idaeus) host-plant. There were four herbivore treatments (control, aphid only, weevil only and a combination of both herbivores) and an ambient (aCO2) or elevated (eCO2) CO2 treatment (390 versus 650 ± 50 μmol/mol) assigned to two raspberry cultivars (cv Glen Ample or Glen Clova) varying in resistance to aphid herbivory. Contrary to our predictions, eCO2 did not increase crop biomass or the C:N ratio of the plant tissues, nor affect herbivore abundance either directly or via the host-plant. Root herbivory reduced belowground crop biomass under aCO2 but not eCO2, suggesting that crops could tolerate attack in a CO2 enriched environment. Root herbivory also increased the C:N ratio in leaf tissue at eCO2, potentially due to decreased N uptake indicated by lower N concentrations found in the roots. Root herbivory greatly increased root C concentrations under both CO2 treatments. Our findings confirm that responses of crop biomass and biochemistry to climate change need examining within the context of herbivory, as biotic interactions appear as important as direct effects of eCO2 on crop productivity. PMID:27379129

  11. Root Herbivores Drive Changes to Plant Primary Chemistry, but Root Loss Is Mitigated under Elevated Atmospheric CO2

    PubMed Central

    McKenzie, Scott W.; Johnson, Scott N.; Jones, T. Hefin; Ostle, Nick J.; Hails, Rosemary S.; Vanbergen, Adam J.

    2016-01-01

    Above- and belowground herbivory represents a major challenge to crop productivity and sustainable agriculture worldwide. How this threat from multiple herbivore pests will change under anthropogenic climate change, via altered trophic interactions and plant response traits, is key to understanding future crop resistance to herbivory. In this study, we hypothesized that atmospheric carbon enrichment would increase the amount (biomass) and quality (C:N ratio) of crop plant resources for above- and belowground herbivore species. In a controlled environment facility, we conducted a microcosm experiment using the large raspberry aphid (Amphorophora idaei), the root feeding larvae of the vine weevil (Otiorhynchus sulcatus), and the raspberry (Rubus idaeus) host-plant. There were four herbivore treatments (control, aphid only, weevil only and a combination of both herbivores) and an ambient (aCO2) or elevated (eCO2) CO2 treatment (390 versus 650 ± 50 μmol/mol) assigned to two raspberry cultivars (cv Glen Ample or Glen Clova) varying in resistance to aphid herbivory. Contrary to our predictions, eCO2 did not increase crop biomass or the C:N ratio of the plant tissues, nor affect herbivore abundance either directly or via the host-plant. Root herbivory reduced belowground crop biomass under aCO2 but not eCO2, suggesting that crops could tolerate attack in a CO2 enriched environment. Root herbivory also increased the C:N ratio in leaf tissue at eCO2, potentially due to decreased N uptake indicated by lower N concentrations found in the roots. Root herbivory greatly increased root C concentrations under both CO2 treatments. Our findings confirm that responses of crop biomass and biochemistry to climate change need examining within the context of herbivory, as biotic interactions appear as important as direct effects of eCO2 on crop productivity. PMID:27379129

  12. Spatial heterogeneity of plant-soil feedback affects root interactions and interspecific competition.

    PubMed

    Hendriks, Marloes; Ravenek, Janneke M; Smit-Tiekstra, Annemiek E; van der Paauw, Jan Willem; de Caluwe, Hannie; van der Putten, Wim H; de Kroon, Hans; Mommer, Liesje

    2015-08-01

    Plant-soil feedback is receiving increasing interest as a factor influencing plant competition and species coexistence in grasslands. However, we do not know how spatial distribution of plant-soil feedback affects plant below-ground interactions. We investigated the way in which spatial heterogeneity of soil biota affects competitive interactions in grassland plant species. We performed a pairwise competition experiment combined with heterogeneous distribution of soil biota using four grassland plant species and their soil biota. Patches were applied as quadrants of 'own' and 'foreign' soils from all plant species in all pairwise combinations. To evaluate interspecific root responses, species-specific root biomass was quantified using real-time PCR. All plant species suffered negative soil feedback, but strength was species-specific, reflected by a decrease in root growth in own compared with foreign soil. Reduction in root growth in own patches by the superior plant competitor provided opportunities for inferior competitors to increase root biomass in these patches. These patterns did not cascade into above-ground effects during our experiment. We show that root distributions can be determined by spatial heterogeneity of soil biota, affecting plant below-ground competitive interactions. Thus, spatial heterogeneity of soil biota may contribute to plant species coexistence in species-rich grasslands. PMID:25871977

  13. Permeability of Plant Young Root Endodermis to Cu Ions and Cu-Citrate Complexes in Corn and Soybean.

    PubMed

    Fu, Yanzhao; Lei, Wenrui; Shen, Zhenguo; Luo, Chunling

    2015-01-01

    The non-selective apoplastic passage of Cu and Cu-citrate complexes into the root stele of monocotyledonous corn and dicotyledonous soybean was investigated using an inorganic-salt-precipitation technique. Either Cu ions or Cu-citrate complexes were drawn into root through the apoplast from the root growth medium, and K4[Fe(CN)6] was subsequently perfused through xylem vessels or the entire root cross section. Based on microscopic identification of the reddish-brown precipitates of copper ferrocyanide in the cell walls of the xylem of corn and soybean roots, Cu(2+) passed through the endodermal barrier into the xylem of both species. When the solution containing 200 μM CuSO4 and 400 μM sodium citrate (containing 199.98 μM Cu-citrate, 0.02 μM Cu(2+)) was drawn via differential pressure gradients into the root xylem while being perfused with K4[Fe(CN)6] through the entire root cross-section, reddish-brown precipitates were observed in the walls of the stele of soybean, but not corn root. However, when a CuSO4 solution containing 0.02 or 0.2 μM free Cu(2+) was used, no reddish-brown precipitates were detected in the stele of either of the two plants. Results indicated that endodermis was permeable to Cu-citrate complexes in primary roots of soybean, but not corn. The permeability of the endodermal barrier to the Cu-citrate complex may vary between dicotyledonous and monocotyledonous plants, which has considerable implications for chelant-enhanced phytoextraction. PMID:26091247

  14. Global-scale latitudinal patterns of plant fine-root nitrogen and phosphorus.

    PubMed

    Yuan, Z Y; Chen, Han Y H; Reich, Peter B

    2011-01-01

    Most water and essential soil nutrient uptake is carried out by fine roots in plants. It is therefore important to understand the global geographic patterns of fine-root nitrogen and phosphorus cycling. Here, by compiling plant root data from 211 studies in 51 countries, we show that live fine roots have low nitrogen (N) and phosphorus (P), but similar N:P ratios when compared with green leaves. The fine-root N:P ratio differs between biomes and declines exponentially with latitude in roots of all diameter classes. This is in contrast to previous reports of a linear latitudinal decline in green leaf N:P, but consistent with nonlinear declines in leaf litter N:P. Whereas the latitudinal N:P decline in both roots and leaves reflects collective influences of climate, soil age and weathering, differences in the shape of the response function may be a result of their different N and P use strategies. PMID:21673665

  15. Can diversity in root architecture explain plant water use efficiency? A modeling study

    PubMed Central

    Tron, Stefania; Bodner, Gernot; Laio, Francesco; Ridolfi, Luca; Leitner, Daniel

    2015-01-01

    Drought stress is a dominant constraint to crop production. Breeding crops with adapted root systems for effective uptake of water represents a novel strategy to increase crop drought resistance. Due to complex interaction between root traits and high diversity of hydrological conditions, modeling provides important information for trait based selection. In this work we use a root architecture model combined with a soil-hydrological model to analyze whether there is a root system ideotype of general adaptation to drought or water uptake efficiency of root systems is a function of specific hydrological conditions. This was done by modeling transpiration of 48 root architectures in 16 drought scenarios with distinct soil textures, rainfall distributions, and initial soil moisture availability. We find that the efficiency in water uptake of root architecture is strictly dependent on the hydrological scenario. Even dense and deep root systems are not superior in water uptake under all hydrological scenarios. Our results demonstrate that mere architectural description is insufficient to find root systems of optimum functionality. We find that in environments with sufficient rainfall before the growing season, root depth represents the key trait for the exploration of stored water, especially in fine soils. Root density, instead, especially near the soil surface, becomes the most relevant trait for exploiting soil moisture when plant water supply is mainly provided by rainfall events during the root system development. We therefore concluded that trait based root breeding has to consider root systems with specific adaptation to the hydrology of the target environment. PMID:26412932

  16. Enhancing Plant Disease Resistance without R Genes.

    PubMed

    Sarma, Birinchi Kumar; Singh, Harikesh Bahadur; Fernando, Dilantha; Silva, Roberto Nascimento; Gupta, Vijai Kumar

    2016-07-01

    Crop plants encounter constant biotic challenges, and these challenges have historically been best managed with resistance (R) genes. However, the rapid evolution of new pathogenic strains along with the nonavailability or nonidentification of R genes in cultivated crop species against a large number of plant pathogens have led researchers to think beyond R genes. Biotechnological tools have shown promise in dealing with such challenges. Technologies such as transgenerational plant immunity, interspecies transfer of pattern recognition receptors (PRRs), pathogen-derived resistance (PDR), gene regulation, and expression of antimicrobial peptides (AMPs) in host plants from other plant species have led to enhanced disease resistance and increased food security. PMID:27113633

  17. Mitigation of antagonistic effects on plant growth due to root co-colonization by dark septate endophytes and ectomycorrhiza.

    PubMed

    Reininger, Vanessa; Sieber, Thomas N

    2013-12-01

    Dark septate endophytes (DSE) are very common root colonizers of woody plant species. Ascomycetes of the Phialocephala fortinii s.l.-Acephala applanata species complex (PAC) are the main representatives of DSE fungi in forest ecosystems. PAC and mycorrhizal fungi share the same habitat, but interactions among PAC, mycorrhizal fungi and plants are poorly understood. We compared the effects of single and dual inoculation of Norway spruce seedlings with PAC and the ectomycorrhizal (ECM) fungus Hebeloma crustuliniforme on host growth, degree of mycorrhization and density of endophytic PAC biomass. Single colonization by H. crustuliniforme or PAC significantly reduced plant biomass. Dual colonization reduced or neutralized plant growth depression caused by single fungal colonization. The degree of mycorrhization was independent on PAC colonization, and mycorrhization significantly reduced endophytic PAC biomass. Plant biomass of dually colonized plants positively correlated with PAC biomass. These results demonstrate the ability of dual inoculation of PAC and H. crustuliniforme to neutralize plant growth depression caused by single fungal inoculation. Our explanations of enhanced plant growth in dually inoculated plants are the inhibition of PAC during root colonization by the ECM mantle and ECM-mediated access to plant growth-promoting nutrients resulting from the mineralization of the potting medium by PAC. PMID:24249297

  18. Zn2+-induced changes at the root level account for the increased tolerance of acclimated tobacco plants

    PubMed Central

    Bazihizina, Nadia; Taiti, Cosimo; Marti, Lucia; Rodrigo-Moreno, Ana; Spinelli, Francesco; Giordano, Cristiana; Caparrotta, Stefania; Gori, Massimo; Azzarello, Elisa; Mancuso, Stefano

    2014-01-01

    Evidence suggests that heavy-metal tolerance can be induced in plants following pre-treatment with non-toxic metal concentrations, but the results are still controversial. In the present study, tobacco plants were exposed to increasing Zn2+ concentrations (up to 250 and/or 500 μM ZnSO4) with or without a 1-week acclimation period with 30 μM ZnSO4. Elevated Zn2+ was highly toxic for plants, and after 3 weeks of treatments there was a marked (≥50%) decline in plant growth in non-acclimated plants. Plant acclimation, on the other hand, increased plant dry mass and leaf area up to 1.6-fold compared with non-acclimated ones. In non-acclimated plants, the addition of 250 μM ZnSO4 led to transient membrane depolarization and stomatal closure within 24h from the addition of the stress; by contrast, the acclimation process was associated with an improved stomatal regulation and a superior ability to maintain a negative root membrane potential, with values on average 37% more negative compared with non-acclimated plants. The different response at the plasma-membrane level between acclimated and non-acclimated plants was associated with an enhanced vacuolar Zn2+ sequestration and up to 2-fold higher expression of the tobacco orthologue of the Arabidopsis thaliana MTP1 gene. Thus, the acclimation process elicited specific detoxification mechanisms in roots that enhanced Zn2+ compartmentalization in vacuoles, thereby improving root membrane functionality and stomatal regulation in leaves following elevated Zn2+ stress. PMID:24928985

  19. Legume presence reduces the decomposition rate of non-legume roots, role of plant traits?

    NASA Astrophysics Data System (ADS)

    De Deyn, Gerlinde B.; Saar, Sirgi; Barel, Janna; Semchenko, Marina

    2016-04-01

    Plant litter traits are known to play an important role in the rate of litter decomposition and mineralization, both for aboveground and belowground litter. However also the biotic and abiotic environment in which the litter decomposes plays a significant role in the rate of decomposition. The presence of living plants may accelerate litter decomposition rates via a priming effects. The size of this effect is expected to be related to the traits of the litter. In this study we focus on root litter, given that roots and their link to ecosystem processes have received relatively little attention in trait-based research. To test the effect of a growing legume plant on root decomposition and the role of root traits in this we used dead roots of 7 different grassland species (comprising grasses, a forb and legumes), determined their C, N, P content and quantified litter mass loss after eight weeks of incubation in soil with and without white clover. We expected faster root decomposition with white clover, especially for root litter with low N content. In contrast we found slower decomposition of grass and forb roots which were poor in N (negative priming) in presence of white clover, while decomposition rates of legume roots were not affected by the presence of white clover. Overall we found that root decomposition can be slowed down in the presence of a living plant and that this effect depends on the traits of the decomposing roots, with a pronounced reduction in root litter poor in N and P, but not in the relatively nutrient-rich legume root litters. The negative priming effect of legume plants on non-legume litter decomposition may have resulted from preferential substrate utilisation by soil microbes.

  20. Classroom Modified Split-Root Technique and Its Application in a Plant Habitat Selection Experiment at the College Level

    ERIC Educational Resources Information Center

    Elliott, Shannon S.; Winter, Peggy A.

    2011-01-01

    The split-root technique produces a plant with two equal root masses. Traditionally, the two root masses of the single plant are cultivated in adjacent pots with or without roots from competitors for the purpose of elucidating habitat preferences. We have tailored this technology for the classroom, adjusting protocols to match resources and time…

  1. Cadmium induces hypodermal periderm formation in the roots of the monocotyledonous medicinal plant Merwilla plumbea

    PubMed Central

    Lux, Alexander; Vaculík, Marek; Martinka, Michal; Lišková, Desana; Kulkarni, Manoj G.; Stirk, Wendy A.; Van Staden, Johannes

    2011-01-01

    Background and Aims Merwilla plumbea is an important African medicinal plant. As the plants grow in soils contaminated with metals from mining activities, the danger of human intoxication exists. An experiment with plants exposed to cadmium (Cd) was performed to investigate the response of M. plumbea to this heavy metal, its uptake and translocation to plant organs and reaction of root tissues. Methods Plants grown from seeds were cultivated in controlled conditions. Hydroponic cultivation is not suitable for this species as roots do not tolerate aquatic conditions, and additional stress by Cd treatment results in total root growth inhibition and death. After cultivation in perlite the plants exposed to 1 and 5 mg Cd L−1 in half-strength Hoagland's solution were compared with control plants. Growth parameters were evaluated, Cd content was determined by inductively coupled plasma mass spectroscopy (ICP-MS) and root structure was investigated using various staining procedures, including the fluorescent stain Fluorol yellow 088 to detect suberin deposition in cell walls. Key Results The plants exposed to Cd were significantly reduced in growth. Most of the Cd taken up by plants after 4 weeks cultivation was retained in roots, and only a small amount was translocated to bulbs and leaves. In reaction to higher Cd concentrations, roots developed a hypodermal periderm close to the root tip. Cells produced by cork cambium impregnate their cell walls by suberin. Conclusions It is suggested that the hypodermal periderm is developed in young root parts in reaction to Cd toxicity to protect the root from radial uptake of Cd ions. Secondary meristems are usually not present in monocotyledonous species. Another interpretation explaining formation of protective suberized layers as a result of periclinal divisions of the hypodermis is discussed. This process may represent an as yet unknown defence reaction of roots when exposed to elemental stress. PMID:21118841

  2. Chemical signals from plants previously infected with root knot nematodes affect behavior of infective juvenile root knot nematodes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Nematodes are a worldwide problem in agriculture, with losses estimated to $100 billion per year in the US. Damage caused by root-knot nematodes (Meloidogyne spp.) (RKN) disrupts the flow of water and nutrients to the plant and increases the plant’s vulnerability to other pathogens. While studies ...

  3. Hydraulic resistances and root geometry parameters in plant transpiration analysis

    NASA Astrophysics Data System (ADS)

    Vogel, Tomas; Votrubova, Jana; Dusek, Jaromir; Dohnal, Michal

    2016-04-01

    Three approximate mesoscopic solutions of soil water flow towards roots: (1) finite difference approximation, (2) steady-state solution, and (3) steady-rate solution, were examined from the point of view of their ability to predict the pressure head variations in the vicinity of roots. The individual solutions were then alternatively used to determine the macroscopic soil hydraulic resistance between bulk soil and root surface. In the next step, macroscopic simulations of coupled soil water flow and root water uptake at a forest site under humid temperate climate were performed. The predicted soil water pressure heads and actual transpiration rates were compared with observed data. The simulation results illustrate uncertainties associated with the estimation of root geometric and hydraulic properties. Regarding the prediction of actual transpiration, the correct characterization of active root system geometry and its hydraulic properties seems far more important than the choice of a particular macroscopic soil hydraulic resistance formula.

  4. COMPREHENSIVE CHEMICAL PROFILING OF GRAMINEOUS PLANT ROOT EXUDATES USING HIGH-RESOLUTION NMR AND MS. (R825433C007)

    EPA Science Inventory

    Root exudates released into soil have important functions in mobilizing metal micronutrients and for causing selective enrichment of plant beneficial soil micro-organisms that colonize the rhizosphere. Analysis of plant root exudates typically has involved chromatographic meth...

  5. A PLANT ROOT SYSTEM ARCHITECTURAL TAXONOMY: A FRAMEWORK FOR ROOT NOMENCLATURE

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Research into root system morphology over the last two centuries, has developed a diverse set of terminologies that are difficult to apply consistently across species and research specialties. In response to a need for better communication, a workshop held by the International Society for Root Rese...

  6. Different bacterial populations associated with the roots and rhizosphere of rice incorporate plant-derived carbon.

    PubMed

    Hernández, Marcela; Dumont, Marc G; Yuan, Quan; Conrad, Ralf

    2015-03-01

    Microorganisms associated with the roots of plants have an important function in plant growth and in soil carbon sequestration. Rice cultivation is the second largest anthropogenic source of atmospheric CH4, which is a significant greenhouse gas. Up to 60% of fixed carbon formed by photosynthesis in plants is transported below ground, much of it as root exudates that are consumed by microorganisms. A stable isotope probing (SIP) approach was used to identify microorganisms using plant carbon in association with the roots and rhizosphere of rice plants. Rice plants grown in Italian paddy soil were labeled with (13)CO2 for 10 days. RNA was extracted from root material and rhizosphere soil and subjected to cesium gradient centrifugation followed by 16S rRNA amplicon pyrosequencing to identify microorganisms enriched with (13)C. Thirty operational taxonomic units (OTUs) were labeled and mostly corresponded to Proteobacteria (13 OTUs) and Verrucomicrobia (8 OTUs). These OTUs were affiliated with the Alphaproteobacteria, Betaproteobacteria, and Deltaproteobacteria classes of Proteobacteria and the "Spartobacteria" and Opitutae classes of Verrucomicrobia. In general, different bacterial groups were labeled in the root and rhizosphere, reflecting different physicochemical characteristics of these locations. The labeled OTUs in the root compartment corresponded to a greater proportion of the 16S rRNA sequences (∼20%) than did those in the rhizosphere (∼4%), indicating that a proportion of the active microbial community on the roots greater than that in the rhizosphere incorporated plant-derived carbon within the time frame of the experiment. PMID:25616793

  7. Different Bacterial Populations Associated with the Roots and Rhizosphere of Rice Incorporate Plant-Derived Carbon

    PubMed Central

    Hernández, Marcela; Yuan, Quan; Conrad, Ralf

    2015-01-01

    Microorganisms associated with the roots of plants have an important function in plant growth and in soil carbon sequestration. Rice cultivation is the second largest anthropogenic source of atmospheric CH4, which is a significant greenhouse gas. Up to 60% of fixed carbon formed by photosynthesis in plants is transported below ground, much of it as root exudates that are consumed by microorganisms. A stable isotope probing (SIP) approach was used to identify microorganisms using plant carbon in association with the roots and rhizosphere of rice plants. Rice plants grown in Italian paddy soil were labeled with 13CO2 for 10 days. RNA was extracted from root material and rhizosphere soil and subjected to cesium gradient centrifugation followed by 16S rRNA amplicon pyrosequencing to identify microorganisms enriched with 13C. Thirty operational taxonomic units (OTUs) were labeled and mostly corresponded to Proteobacteria (13 OTUs) and Verrucomicrobia (8 OTUs). These OTUs were affiliated with the Alphaproteobacteria, Betaproteobacteria, and Deltaproteobacteria classes of Proteobacteria and the “Spartobacteria” and Opitutae classes of Verrucomicrobia. In general, different bacterial groups were labeled in the root and rhizosphere, reflecting different physicochemical characteristics of these locations. The labeled OTUs in the root compartment corresponded to a greater proportion of the 16S rRNA sequences (∼20%) than did those in the rhizosphere (∼4%), indicating that a proportion of the active microbial community on the roots greater than that in the rhizosphere incorporated plant-derived carbon within the time frame of the experiment. PMID:25616793

  8. Quantitative 3D Analysis of Plant Roots Growing in Soil Using Magnetic Resonance Imaging.

    PubMed

    van Dusschoten, Dagmar; Metzner, Ralf; Kochs, Johannes; Postma, Johannes A; Pflugfelder, Daniel; Bühler, Jonas; Schurr, Ulrich; Jahnke, Siegfried

    2016-03-01

    Precise measurements of root system architecture traits are an important requirement for plant phenotyping. Most of the current methods for analyzing root growth require either artificial growing conditions (e.g. hydroponics), are severely restricted in the fraction of roots detectable (e.g. rhizotrons), or are destructive (e.g. soil coring). On the other hand, modalities such as magnetic resonance imaging (MRI) are noninvasive and allow high-quality three-dimensional imaging of roots in soil. Here, we present a plant root imaging and analysis pipeline using MRI together with an advanced image visualization and analysis software toolbox named NMRooting. Pots up to 117 mm in diameter and 800 mm in height can be measured with the 4.7 T MRI instrument used here. For 1.5 l pots (81 mm diameter, 300 mm high), a fully automated system was developed enabling measurement of up to 18 pots per day. The most important root traits that can be nondestructively monitored over time are root mass, length, diameter, tip number, and growth angles (in two-dimensional polar coordinates) and spatial distribution. Various validation measurements for these traits were performed, showing that roots down to a diameter range between 200 μm and 300 μm can be quantitatively measured. Root fresh weight correlates linearly with root mass determined by MRI. We demonstrate the capabilities of MRI and the dedicated imaging pipeline in experimental series performed on soil-grown maize (Zea mays) and barley (Hordeum vulgare) plants. PMID:26729797

  9. Quantitative 3D Analysis of Plant Roots Growing in Soil Using Magnetic Resonance Imaging1[OPEN

    PubMed Central

    Kochs, Johannes; Pflugfelder, Daniel

    2016-01-01

    Precise measurements of root system architecture traits are an important requirement for plant phenotyping. Most of the current methods for analyzing root growth require either artificial growing conditions (e.g. hydroponics), are severely restricted in the fraction of roots detectable (e.g. rhizotrons), or are destructive (e.g. soil coring). On the other hand, modalities such as magnetic resonance imaging (MRI) are noninvasive and allow high-quality three-dimensional imaging of roots in soil. Here, we present a plant root imaging and analysis pipeline using MRI together with an advanced image visualization and analysis software toolbox named NMRooting. Pots up to 117 mm in diameter and 800 mm in height can be measured with the 4.7 T MRI instrument used here. For 1.5 l pots (81 mm diameter, 300 mm high), a fully automated system was developed enabling measurement of up to 18 pots per day. The most important root traits that can be nondestructively monitored over time are root mass, length, diameter, tip number, and growth angles (in two-dimensional polar coordinates) and spatial distribution. Various validation measurements for these traits were performed, showing that roots down to a diameter range between 200 μm and 300 μm can be quantitatively measured. Root fresh weight correlates linearly with root mass determined by MRI. We demonstrate the capabilities of MRI and the dedicated imaging pipeline in experimental series performed on soil-grown maize (Zea mays) and barley (Hordeum vulgare) plants. PMID:26729797

  10. Exploring the transfer of recent plant photosynthates to soil microbes: mycorrhizal pathway vs direct root exudation

    PubMed Central

    Kaiser, Christina; Kilburn, Matt R; Clode, Peta L; Fuchslueger, Lucia; Koranda, Marianne; Cliff, John B; Solaiman, Zakaria M; Murphy, Daniel V

    2015-01-01

    Plants rapidly release photoassimilated carbon (C) to the soil via direct root exudation and associated mycorrhizal fungi, with both pathways promoting plant nutrient availability. This study aimed to explore these pathways from the root's vascular bundle to soil microbial communities. Using nanoscale secondary ion mass spectrometry (NanoSIMS) imaging and 13C-phospho- and neutral lipid fatty acids, we traced in-situ flows of recently photoassimilated C of 13CO2-exposed wheat (Triticum aestivum) through arbuscular mycorrhiza (AM) into root- and hyphae-associated soil microbial communities. Intraradical hyphae of AM fungi were significantly 13C-enriched compared to other root-cortex areas after 8 h of labelling. Immature fine root areas close to the root tip, where AM features were absent, showed signs of passive C loss and co-location of photoassimilates with nitrogen taken up from the soil solution. A significant and exclusively fresh proportion of 13C-photosynthates was delivered through the AM pathway and was utilised by different microbial groups compared to C directly released by roots. Our results indicate that a major release of recent photosynthates into soil leave plant roots via AM intraradical hyphae already upstream of passive root exudations. AM fungi may act as a rapid hub for translocating fresh plant C to soil microbes. PMID:25382456

  11. A manifold learning based identification of latent variations in root cross sections of plants

    NASA Astrophysics Data System (ADS)

    Chakravarty, Sumit; Banerjee, Madhushri

    2012-06-01

    Currently a lot of plant biology research focuses on understanding the genetic, physiological, and ecology of plants. Root is an important organ for plant to uptake nutrient and water from the surrounding soil. The capability of plant to obtain nutrient and water is closely related to root physiology. Quantitative measurement and analysis of plant root architecture parameters are very important for understanding and study growth of plant. A fundamental aim of developmental plant root biology is to understand how the three-dimensional morphology of plant roots arises through cellular mechanisms. However, traditional anatomical studies of plant development have mainly relied on two-dimensional images. Though this may be sufficient for some aspects of plant biology, deeper understanding of plant growth and function increasingly requires at least some amount of three dimensional measures and use chemical staining as a technique to bring pseudo structure and segmentation to the cross section image data. Thus parameters like uniformity of illumination and thickness of the specimen then becomes critical. Unfortunately these are also the causes of major variations. The variation of thickness of specimen can be interpreted as an effect which increases the latent dimensionality of the data. Addressing the variability due to specimen thickness can then be viewed in a manifold learning framework, wherein it is assumed that the data of interest lies on an embedded manifold within the higher-dimensional space and can be visualized in low dimensional space, using manifold learning constraints.

  12. Transgenic plants with enhanced growth characteristics

    DOEpatents

    Unkefer, Pat J.; Anderson, Penelope S.; Knight, Thomas J.

    2016-09-06

    The invention relates to transgenic plants exhibiting dramatically enhanced growth rates, greater seed and fruit/pod yields, earlier and more productive flowering, more efficient nitrogen utilization, increased tolerance to high salt conditions, and increased biomass yields. In one embodiment, transgenic plants engineered to over-express both glutamine phenylpyruvate transaminase (GPT) and glutamine synthetase (GS) are provided. The GPT+GS double-transgenic plants of the invention consistently exhibit enhanced growth characteristics, with T0 generation lines showing an increase in biomass over wild type counterparts of between 50% and 300%. Generations that result from sexual crosses and/or selfing typically perform even better, with some of the double-transgenic plants achieving an astounding four-fold biomass increase over wild type plants.

  13. An index for plant water deficit based on root-weighted soil water content

    NASA Astrophysics Data System (ADS)

    Shi, Jianchu; Li, Sen; Zuo, Qiang; Ben-Gal, Alon

    2015-03-01

    Governed by atmospheric demand, soil water conditions and plant characteristics, plant water status is dynamic, complex, and fundamental to efficient agricultural water management. To explore a centralized signal for the evaluation of plant water status based on soil water status, two greenhouse experiments investigating the effect of the relative distribution between soil water and roots on wheat and rice were conducted. Due to the significant offset between the distributions of soil water and roots, wheat receiving subsurface irrigation suffered more from drought than wheat under surface irrigation, even when the arithmetic averaged soil water content (SWC) in the root zone was higher. A significant relationship was found between the plant water deficit index (PWDI) and the root-weighted (rather than the arithmetic) average SWC over root zone. The traditional soil-based approach for the estimation of PWDI was improved by replacing the arithmetic averaged SWC with the root-weighted SWC to take the effect of the relative distribution between soil water and roots into consideration. These results should be beneficial for scheduling irrigation, as well as for evaluating plant water consumption and root density profile.

  14. Abundance of rice root aphid among selected plant species and on plants grown with different soil-surface media

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The rice root aphid, Rhopalosiphum rufiabdominalis (Sasaki), is distributed worldwide and colonizes a wide range of plants. However, relatively little is known about the suitability of different host plants, optimal rearing techniques, and the aphid’s impact on plant fitness. To improve understand...

  15. The Response of the Root Apex in Plant Adaptation to Iron Heterogeneity in Soil

    PubMed Central

    Li, Guangjie; Kronzucker, Herbert J.; Shi, Weiming

    2016-01-01

    Iron (Fe) is an essential micronutrient for plant growth and development, and is frequently limiting. By contrast, over-accumulation of Fe in plant tissues leads to toxicity. In soils, the distribution of Fe is highly heterogeneous. To cope with this heterogeneity, plant roots engage an array of adaptive responses to adjust their morphology and physiology. In this article, we review root morphological and physiological changes in response to low- and high-Fe conditions and highlight differences between these responses. We especially focus on the role of the root apex in dealing with the stresses resulting from Fe shortage and excess. PMID:27047521

  16. Influence of Merosesquiterpenoids from Marine Sponges on Seedling Root Growth of Agricultural Plants.

    PubMed

    Chaikina, Elena L; Utkina, Natalia K; Anisimov, Mikhail M

    2016-01-01

    The impact of the merosesquiterpenoids avarol (1), avarone (2), 18-methylaminoavarone (3), melemeleone A (4), isospongiaquinone (5), ilimaquinone (6), and smenoquinone (7), isolated from marine sponges of the Dictyoceratida order, was studied on the root growth of seedlings of buckwheat (Fagopyrumesculentum Moench), wheat (Triticumaestivum L.), soy (Glycine max (L.) Merr.), and barley (Hordeumvulgare L.). Compounds 2and 6 were effective for the root growth of wheat seedlings, compound 3 stimulated the root growth of seedlings of buckwheat and soy, compound 4 affected the roots of barley seedlings, and compound 5 stimulated the root growth of seedlings of buckwheat and barley. Compounds 1 and 7 showed no activity on the root growth of the seedlings of any of the studied plants. The stimulatory effect depends on the chemical structure of the compounds and the type of crop plant. PMID:26996006

  17. Ethylene Supports Colonization of Plant Roots by the Mutualistic Fungus Piriformospora indica

    PubMed Central

    Khatabi, Behnam; Molitor, Alexandra; Lindermayr, Christian; Pfiffi, Stefanie; Durner, Jörg; von Wettstein, Diter; Kogel, Karl-Heinz; Schäfer, Patrick

    2012-01-01

    The mutualistic basidiomycete Piriformospora indica colonizes roots of mono- and dicotyledonous plants, and thereby improves plant health and yield. Given the capability of P. indica to colonize a broad range of hosts, it must be anticipated that the fungus has evolved efficient strategies to overcome plant immunity and to establish a proper environment for nutrient acquisition and reproduction. Global gene expression studies in barley identified various ethylene synthesis and signaling components that were differentially regulated in P. indica-colonized roots. Based on these findings we examined the impact of ethylene in the symbiotic association. The data presented here suggest that P. indica induces ethylene synthesis in barley and Arabidopsis roots during colonization. Moreover, impaired ethylene signaling resulted in reduced root colonization, Arabidopsis mutants exhibiting constitutive ethylene signaling, -synthesis or ethylene-related defense were hyper-susceptible to P. indica. Our data suggest that ethylene signaling is required for symbiotic root colonization by P. indica. PMID:22536394

  18. Plant Roots Increase Bacterivorous Nematode Dispersion through Nonuniform Glass-bead Media.

    PubMed

    Trap, Jean; Bernard, Laetitia; Brauman, Alain; Pablo, Anne-Laure; Plassard, Claude; Ranoarisoa, Mahafaka Patricia; Blanchart, Eric

    2015-12-01

    Dispersion of bacterivorous nematodes in soil is a crucial ecological process that permits settlement and exploitation of new bacterial-rich patches. Although plant roots, by modifying soil structure, are likely to influence this process, they have so far been neglected. In this study, using an original three-compartment microcosm experimental design and polyvinyl chloride (PVC) bars to mimic plant roots, we tested the ability of roots to improve the dispersion of bacterivorous nematode populations through two wet, nonuniform granular (glass bead) media imitating contrasting soil textures. We showed that artificial roots increased migration time of bacterivorous nematode populations in the small-bead medium, suggesting that plant roots may play an important role in nematode dispersion in fine-textured soils or when soil compaction is high. PMID:26941457

  19. Plant Roots Increase Bacterivorous Nematode Dispersion through Nonuniform Glass-bead Media

    PubMed Central

    Trap, Jean; Bernard, Laetitia; Brauman, Alain; Pablo, Anne-Laure; Plassard, Claude; Ranoarisoa, Mahafaka Patricia; Blanchart, Eric

    2015-01-01

    Dispersion of bacterivorous nematodes in soil is a crucial ecological process that permits settlement and exploitation of new bacterial-rich patches. Although plant roots, by modifying soil structure, are likely to influence this process, they have so far been neglected. In this study, using an original three-compartment microcosm experimental design and polyvinyl chloride (PVC) bars to mimic plant roots, we tested the ability of roots to improve the dispersion of bacterivorous nematode populations through two wet, nonuniform granular (glass bead) media imitating contrasting soil textures. We showed that artificial roots increased migration time of bacterivorous nematode populations in the small-bead medium, suggesting that plant roots may play an important role in nematode dispersion in fine-textured soils or when soil compaction is high. PMID:26941457

  20. Optical methods for creating delivery systems of chemical compounds to plant roots

    NASA Astrophysics Data System (ADS)

    Kuznetsov, Pavel E.; Rogacheva, Svetlana M.; Arefeva, Oksana A.; Minin, Dmitryi V.; Tolmachev, Sergey A.; Kupadze, Machammad S.

    2004-08-01

    Spectrophotometric and fluorescence methods have been used for creation and investigation of various systems of target delivery of chemical compounds to roots of plants. The possibility of using liposomes, incrusted by polysaccharides of the external surface of nitrogen-fixing rizospheric bacteria Azospirillum brasilense SP 245, and nanoparticles incrusted by polysaccharides of wheat roots, as the named systems has been shown. The important role of polysaccharide-polysaccharide interaction in the adsorption processes of bacteria on wheat roots has been demonstrated.

  1. [Some peculiar features of liquid supply to the root medium of plants growing in microgravity

    NASA Technical Reports Server (NTRS)

    Podol'skii, I. G.; Sychev, V. N.; Levinskikh, M. A.; Strugov, O. M.; Bingham, G. E.; Salisbury, F. B. (Principal Investigator)

    1998-01-01

    Sixteen point probes monitored moisture level in the root medium of the wheat plants grown in greenhouse SVET on the MIR/NASA space science program. The article outlines types of water migration in the absence of gravity. Hydrophysical characteristics of perspective root media have been explored. Results of the water supply monitoring and control in the course of experiment are reported. The authors put forward porous root media to facilitate water migration and aeration.

  2. Distribution of Pseudomonas fluorescent bacteria in soils and in the root zone of plants.

    PubMed

    Sorokina, T A; Mishustin, E N

    1978-01-01

    The authors studied the ecology of fluorescent bacteria of the genus Pesudomonas. These were found to proliferate most actively in soils very high in fresh organic matter. In grassy and woody residue their numbers attained 30--60%, depending on the specific methods of bacterial sowing. Pseudomonas was particularly numerous in the root zone of plants fertilized by external metabolites of roots and decomposed roots and leaves. PMID:754809

  3. Root Foraging Increases Performance of the Clonal Plant Potentilla reptans in Heterogeneous Nutrient Environments

    PubMed Central

    Wang, Zhengwen; van Kleunen, Mark; During, Heinjo J.; Werger, Marinus J. A.

    2013-01-01

    Background Plastic root-foraging responses have been widely recognized as an important strategy for plants to explore heterogeneously distributed resources. However, the benefits and costs of root foraging have received little attention. Methodology/Principal Findings In a greenhouse experiment, we grew pairs of connected ramets of 22 genotypes of the stoloniferous plant Potentilla reptans in paired pots, between which the contrast in nutrient availability was set as null, medium and high, but with the total nutrient amount kept the same. We calculated root-foraging intensity of each individual ramet pair as the difference in root mass between paired ramets divided by the total root mass. For each genotype, we then calculated root-foraging ability as the slope of the regression of root-foraging intensity against patch contrast. For all genotypes, root-foraging intensity increased with patch contrast and the total biomass and number of offspring ramets were lowest at high patch contrast. Among genotypes, root-foraging intensity was positively related to production of offspring ramets and biomass in the high patch-contrast treatment, which indicates an evolutionary benefit of root foraging in heterogeneous environments. However, we found no significant evidence that the ability of plastic foraging imposes costs under homogeneous conditions (i.e. when foraging is not needed). Conclusions/Significance Our results show that plants of P. reptans adjust their root-foraging intensity according to patch contrast. Moreover, the results show that the root foraging has an evolutionary advantage in heterogeneous environments, while costs of having the ability of plastic root foraging were absent or very small. PMID:23472211

  4. Green Roots: Photosynthesis and Photoautotrophy in an Underground Plant Organ.

    PubMed Central

    Flores, H. E.; Dai, Yr.; Cuello, J. L.; Maldonado-Mendoza, I. E.; Loyola-Vargas, V. M.

    1993-01-01

    The potential for photosynthetic and photoautotrophic growth was studied in hairy root cultures of Asteraceae and Solanaceae species. Upon transfer to light, initially heterotrophic root cultures of Acmella oppositifolia and Datura innoxia greened rapidly, differentiated chloroplasts, and developed light-dependent CO2 fixation in the cortical cells. Photosynthetic potential was expressed in root cultures of all the Asteraceae genera examined (Acmella, Artemisia, Rudbeckia, Stevia, and Tagetes). Hairy roots of A. oppositifolia and D. innoxia were further adapted to photoautotrophy by growing in the presence of light and added CO2 (1-5%) and by direct or sequential transfers into media containing progressively lower sugar concentrations. The transition to photoautotrophy was accompanied by an increase in CO2 fixation and in the specific activity of 1,5-ribulose-bisphosphate carboxylase/ oxygenase (Rubisco). During the adaptation of A. oppositifolia roots to photoautotrophy, the ratio of Rubisco to phosphoenolpyruvate carboxylase increased significantly, approaching that found in the leaves. The levels and patterns of alkaloids and polyacetylenes produced by Solanaceae and Asteraceae hairy roots, respectively, were dramatically altered in photomixotrophic and photoautotrophic cultures. Photoautotrophic roots of A. oppositifolia have been mainitained in vitro for over 2 years. PMID:12231691

  5. Discovery of novel plant interaction determinants from the genomes of 163 root nodule bacteria

    DOE PAGESBeta

    Seshadri, Rekha; Reeve, Wayne G.; Ardley, Julie K.; Tennessen, Kristin; Woyke, Tanja; Kyrpides, Nikos C.; Ivanova, Natalia N.

    2015-11-20

    Root nodule bacteria (RNB) or “rhizobia” are a type of plant growth promoting bacteria, typified by their ability to fix nitrogen for their plant host, fixing nearly 65% of the nitrogen currently utilized in sustainable agricultural production of legume crops and pastures. In this study, we sequenced the genomes of 110 RNB from diverse hosts and biogeographical regions, and undertook a global exploration of all available RNB genera with the aim of identifying novel genetic determinants of symbiotic association and plant growth promotion. Specifically, we performed a subtractive comparative analysis with non-RNB genomes, employed relevant transcriptomic data, and leveraged phylogeneticmore » distribution patterns and sequence signatures based on known precepts of symbioticand host-microbe interactions. A total of 184 protein families were delineated, including known factors for nodulation and nitrogen fixation, and candidates with previously unexplored functions, for which a role in host-interaction, -regulation, biocontrol, and more, could be posited. Lastly, these analyses expand our knowledge of the RNB purview and provide novel targets for strain improvement in the ultimate quest to enhance plant productivity and agricultural sustainability.« less

  6. Discovery of novel plant interaction determinants from the genomes of 163 root nodule bacteria

    SciTech Connect

    Seshadri, Rekha; Reeve, Wayne G.; Ardley, Julie K.; Tennessen, Kristin; Woyke, Tanja; Kyrpides, Nikos C.; Ivanova, Natalia N.

    2015-11-20

    Root nodule bacteria (RNB) or “rhizobia” are a type of plant growth promoting bacteria, typified by their ability to fix nitrogen for their plant host, fixing nearly 65% of the nitrogen currently utilized in sustainable agricultural production of legume crops and pastures. In this study, we sequenced the genomes of 110 RNB from diverse hosts and biogeographical regions, and undertook a global exploration of all available RNB genera with the aim of identifying novel genetic determinants of symbiotic association and plant growth promotion. Specifically, we performed a subtractive comparative analysis with non-RNB genomes, employed relevant transcriptomic data, and leveraged phylogenetic distribution patterns and sequence signatures based on known precepts of symbioticand host-microbe interactions. A total of 184 protein families were delineated, including known factors for nodulation and nitrogen fixation, and candidates with previously unexplored functions, for which a role in host-interaction, -regulation, biocontrol, and more, could be posited. Lastly, these analyses expand our knowledge of the RNB purview and provide novel targets for strain improvement in the ultimate quest to enhance plant productivity and agricultural sustainability.

  7. Discovery of Novel Plant Interaction Determinants from the Genomes of 163 Root Nodule Bacteria

    PubMed Central

    Seshadri, Rekha; Reeve, Wayne G.; Ardley, Julie K.; Tennessen, Kristin; Woyke, Tanja; Kyrpides, Nikos C.; Ivanova, Natalia N.

    2015-01-01

    Root nodule bacteria (RNB) or “rhizobia” are a type of plant growth promoting bacteria, typified by their ability to fix nitrogen for their plant host, fixing nearly 65% of the nitrogen currently utilized in sustainable agricultural production of legume crops and pastures. In this study, we sequenced the genomes of 110 RNB from diverse hosts and biogeographical regions, and undertook a global exploration of all available RNB genera with the aim of identifying novel genetic determinants of symbiotic association and plant growth promotion. Specifically, we performed a subtractive comparative analysis with non-RNB genomes, employed relevant transcriptomic data, and leveraged phylogenetic distribution patterns and sequence signatures based on known precepts of symbiotic- and host-microbe interactions. A total of 184 protein families were delineated, including known factors for nodulation and nitrogen fixation, and candidates with previously unexplored functions, for which a role in host-interaction, -regulation, biocontrol, and more, could be posited. These analyses expand our knowledge of the RNB purview and provide novel targets for strain improvement in the ultimate quest to enhance plant productivity and agricultural sustainability. PMID:26584898

  8. Differential metabolic responses of Beauveria bassiana cultured in pupae extracts, root exudates and its interactions with insect and plant.

    PubMed

    Luo, Feifei; Wang, Qian; Yin, Chunlin; Ge, Yinglu; Hu, Fenglin; Huang, Bo; Zhou, Hong; Bao, Guanhu; Wang, Bin; Lu, Ruili; Li, Zengzhi

    2015-09-01

    and distilled water. This indicates that fungal fatty acid metabolism is enhanced when contacting insect, but when in the absence of insect hosts NRP synthesis is increased. Ornithine, arginine and GABA are decreased in mycelia cultured in pupae extracts and root exudates but remain unchanged in distilled water, which suggests that they may be associated with fungal cross-talk with insects and plants. Trehalose and mannitol are decreased while adenine is increased in three conditions, signifying carbon shortage in cells. Together, these results unveil that B. bassiana has differential metabolic responses in pupae extracts and root exudates, and metabolic similarity in root exudates and distilled water is possibly due to the lack of insect components. PMID:25584432

  9. Simultaneous monitoring of electrical capacitance and water uptake activity of plant root system

    NASA Astrophysics Data System (ADS)

    Cseresnyés, Imre; Takács, Tünde; Füzy, Anna; Rajkai, Kálmán

    2014-10-01

    Pot experiments were designed to test the applicability of root electrical capacitance measurement for in situ monitoring of root water uptake activity by growing cucumber and bean cultivars in a growth chamber. Half of the plants were inoculated with Funneliformis mosseae arbuscular mycorrhizal fungi, while the other half served as non-infected controls. Root electrical capacitance and daily transpiration were monitored during the whole plant ontogeny. Phenology-dependent changes of daily transpiration (related to root water uptake) and root electrical capacitance proved to be similar as they showed upward trends from seedling emergence to the beginning of flowering stage, and thereafter decreased continuously during fruit setting. A few days after arbuscular mycorrhizal fungi-colonization, daily transpiration and root electrical capacitance of infected plants became significantly higher than those of non-infected counterparts, and the relative increment of the measured parameters was greater for the more highly mycorrhizal-dependent bean cultivar compared to that of cucumber. Arbuscular mycorrhizal fungi colonization caused 29 and 69% relative increment in shoot dry mass for cucumbers and beans, respectively. Mycorrhization resulted in 37% increase in root dry mass for beans, but no significant difference was observed for cucumbers. Results indicate the potential of root electrical capacitance measurements for monitoring the changes and differences of root water uptake rate.

  10. Evolving technologies for growing, imaging and analyzing 3D root system architecture of crop plants.

    PubMed

    Piñeros, Miguel A; Larson, Brandon G; Shaff, Jon E; Schneider, David J; Falcão, Alexandre Xavier; Yuan, Lixing; Clark, Randy T; Craft, Eric J; Davis, Tyler W; Pradier, Pierre-Luc; Shaw, Nathanael M; Assaranurak, Ithipong; McCouch, Susan R; Sturrock, Craig; Bennett, Malcolm; Kochian, Leon V

    2016-03-01

    A plant's ability to maintain or improve its yield under limiting conditions, such as nutrient deficiency or drought, can be strongly influenced by root system architecture (RSA), the three-dimensional distribution of the different root types in the soil. The ability to image, track and quantify these root system attributes in a dynamic fashion is a useful tool in assessing desirable genetic and physiological root traits. Recent advances in imaging technology and phenotyping software have resulted in substantive progress in describing and quantifying RSA. We have designed a hydroponic growth system which retains the three-dimensional RSA of the plant root system, while allowing for aeration, solution replenishment and the imposition of nutrient treatments, as well as high-quality imaging of the root system. The simplicity and flexibility of the system allows for modifications tailored to the RSA of different crop species and improved throughput. This paper details the recent improvements and innovations in our root growth and imaging system which allows for greater image sensitivity (detection of fine roots and other root details), higher efficiency, and a broad array of growing conditions for plants that more closely mimic those found under field conditions. PMID:26683583

  11. Plant hairy root cultures as plasmodium modulators of the slime mold emergent computing substrate Physarum polycephalum.

    PubMed

    Ricigliano, Vincent; Chitaman, Javed; Tong, Jingjing; Adamatzky, Andrew; Howarth, Dianella G

    2015-01-01

    Roots of the medicinal plant Valeriana officinalis are well-studied for their various biological activities. We applied genetically transformed V. officinalis root biomass to exert control of Physarum polycephalum, an amoeba-based emergent computing substrate. The plasmodial stage of the P. polycephalum life cycle constitutes a single, multinucleate cell visible by unaided eye. The plasmodium modifies its network of oscillating protoplasm in response to spatial configurations of attractants and repellents, a behavior that is interpreted as biological computation. To program the computing behavior of P. polycephalum, a diverse and sustainable library of plasmodium modulators is required. Hairy roots produced by genetic transformation with Agrobacterium rhizogenes are a metabolically stable source of bioactive compounds. Adventitious roots were induced on in vitro V. officinalis plants following infection with A. rhizogenes. A single hairy root clone was selected for massive propagation and the biomass was characterized in P. polycephalum chemotaxis, maze-solving, and electrical activity assays. The Agrobacterium-derived roots of V. officinalis elicited a positive chemotactic response and augmented maze-solving behavior. In a simple plasmodium circuit, introduction of hairy root biomass stimulated the oscillation patterns of slime mold's surface electrical activity. We propose that manipulation of P. polycephalum with the plant root culture platform can be applied to the development of slime mold microfluidic devices as well as future models for engineering the plant rhizosphere. PMID:26236301

  12. Plant hairy root cultures as plasmodium modulators of the slime mold emergent computing substrate Physarum polycephalum

    PubMed Central

    Ricigliano, Vincent; Chitaman, Javed; Tong, Jingjing; Adamatzky, Andrew; Howarth, Dianella G.

    2015-01-01

    Roots of the medicinal plant Valeriana officinalis are well-studied for their various biological activities. We applied genetically transformed V. officinalis root biomass to exert control of Physarum polycephalum, an amoeba-based emergent computing substrate. The plasmodial stage of the P. polycephalum life cycle constitutes a single, multinucleate cell visible by unaided eye. The plasmodium modifies its network of oscillating protoplasm in response to spatial configurations of attractants and repellents, a behavior that is interpreted as biological computation. To program the computing behavior of P. polycephalum, a diverse and sustainable library of plasmodium modulators is required. Hairy roots produced by genetic transformation with Agrobacterium rhizogenes are a metabolically stable source of bioactive compounds. Adventitious roots were induced on in vitro V. officinalis plants following infection with A. rhizogenes. A single hairy root clone was selected for massive propagation and the biomass was characterized in P. polycephalum chemotaxis, maze-solving, and electrical activity assays. The Agrobacterium-derived roots of V. officinalis elicited a positive chemotactic response and augmented maze-solving behavior. In a simple plasmodium circuit, introduction of hairy root biomass stimulated the oscillation patterns of slime mold's surface electrical activity. We propose that manipulation of P. polycephalum with the plant root culture platform can be applied to the development of slime mold microfluidic devices as well as future models for engineering the plant rhizosphere. PMID:26236301

  13. Effects of contrasting rooting distribution patterns on plant transpiration along a precipitation gradient

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Understanding and predicting ecosystem functioning in water limited ecosystems requires a thorough assessment of the role plant root systems. Widespread ecological phenomena such as shrub encroachment may drastically change root distribution in the soil profile affecting the uptake of water and nutr...

  14. Effects of plant growth promoting rhizobacteria (PGPR) on rooting and root growth of kiwifruit (Actinidia deliciosa) stem cuttings.

    PubMed

    Erturk, Yasar; Ercisli, Sezai; Haznedar, Ayhan; Cakmakci, Ramazan

    2010-01-01

    The effects of plant growth promoting rhizobacteria (PGPR) on the rooting and root growth of semi-hardwood and hardwood kiwifruit stem cuttings were investigated. The PGPR used were Bacillus RC23, Paenibacillus polymyxa RC05, Bacillus subtilis OSU142, Bacillus RC03, Comamonas acidovorans RC41, Bacillus megaterium RC01 and Bacillus simplex RC19. All the bacteria showed indole-3-acetic acid (IAA) producing capacity. Among the PGPR used, the highest rooting ratios were obtained at 47.50% for semi-hardwood stem cuttings from Bacillus RC03 and Bacillus simplex RC19 treatments and 42.50% for hardwood stem cuttings from Bacillus RC03. As well, Comamonas acidovorans RC41 inoculations indicated higher value than control treatments. The results suggest that these PGPR can be used in organic nursery material production and point to the feasibility of synthetic auxin (IBA) replacement by organic management based on PGPR. PMID:21157636

  15. Elevated CO2 and plant species diversity interact to slow root decomposition

    SciTech Connect

    De Graaff, Marie-Anne; Schadt, Christopher Warren; Rula, Kelly L; Six, Johan W U A; Schweitzer, Jennifer A; Classen, Aimee T

    2011-01-01

    Changes in plant species diversity can result in synergistic increases in decomposition rates, while elevated atmospheric CO2 can slow the decomposition rates; yet it remains unclear how diversity and changes in atmospheric CO2 may interact to alter root decomposition. To investigate how elevated CO2 interacts with changes in root-litter diversity to alter decomposition rates, we conducted a 120-day laboratory incubation. Roots from three species (Trifolium repens, Lespedeza cuneata, and Festuca pratense) grown under ambient or elevated CO2 were incubated individually or in combination in soils that were exposed to ambient or elevated CO2 for five years. Our experiment resulted in two main findings: (1) Roots from T. repens and L. cuneata, both nitrogen (N) fixers, grown under elevated CO2 treatments had significantly slower decomposition rates than similar roots grown under ambient CO2 treatments; but the decomposition rate of F. pratense roots (a non-N-fixing species) was similar regardless of CO2 treatment. (2) Roots of the three species grown under ambient CO2 and decomposed in combination with each other had faster decomposition rates than when they were decomposed as single species. However, roots of the three species grown under elevated CO2 had similar decomposition rates when they were incubated alone or in combination with other species. These data suggest that if elevated CO2 reduces the root decomposition rate of even a few species in the community, it may slow root decomposition of the entire plant community.

  16. Root Exudation by Aphid Leaf Infestation Recruits Root-Associated Paenibacillus spp. to Lead Plant Insect Susceptibility.

    PubMed

    Kim, Bora; Song, Geun Cheol; Ryu, Choong-Min

    2016-03-01

    Aphids are a large group of hemipteran pests that affect the physiology, growth, and development of plants by using piercing mouthparts to consume fluids from the host. Based an recent data, aphids modulate the microbiomes of plants and thereby affect the overall outcome of the biological interaction. However, in a few reports, aboveground aphids manipulate the metabolism of the host and facilitate infestations by rhizosphere bacteria (rhizobacteria). In this study, we evaluated whether aphids alter the plant resistance that is mediated by the bacterial community of the root system. The rhizobacteria were affected by aphid infestation of pepper, and a large population of gram-positive bacteria was detected. Notably, Paenibacillus spp. were the unique gram-positive bacteria to respond to changes induced by the aphids. Paenibacillus polymyxa E681 was used as a rhizobacterium model to assess the recruitment of bacteria to the rhizosphere by the phloem-sucking of aphids and to test the effect of P. polymyxa on the susceptibility of plants to aphids. The root exudates secreted from peppers infested with aphids increased the growth rate of P. polymyxa E681. The application of P. polymyxa E681 to pepper roots promoted the colonization of aphids within 2 days of inoculation. Collectively, our results suggest that aphid infestation modulated the root exudation, which led to the recruitment of rhizobacteria that manipulated the resistance of peppers to aphids. In this study, new information is provided on how the infestation of insects is facilitated through insect-derived modulation of plant resistance with the attraction of gram-positive rhizobacteria. PMID:26699743

  17. Chemotactic response of plant-growth-promoting bacteria towards roots of vesicular-arbuscular mycorrhizal tomato plants.

    PubMed

    Gupta Sood, Sushma

    2003-08-01

    The chemotactic responses of the plant-growth-promoting rhizobacteria Azotobacter chroococcum and Pseudomonas fluorescens to roots of vesicular-arbuscular mycorrhizal (Glomus fasciculatum) tomato plants were determined. A significantly (P=0.05) greater number of bacterial cells of wild strains were attracted towards vesicular-arbuscular mycorrhizal tomato roots compared to non-vesicular-arbuscular mycorrhizal tomato roots. Substances exuded by roots served as chemoattractants for these bacteria. P. fluorescens was strongly attracted towards citric and malic acids, which were predominant constituents in root exudates of tomato plants. A. chroococcum showed a stronger response towards sugars than amino acids, but the response was weakest towards organic acids. The effects of temperature, pH, and soil water matric potential on bacterial chemotaxis towards roots were also investigated. In general, significantly (P=0.05) greater chemotactic responses of bacteria were observed at higher water matric potentials (0, -1, and -5 kPa), slightly acidic to neutral pH (6, 6.5 and 7), and at 20-30 degrees C (depending on the bacterium) than in other environmental conditions. It is suggested that chemotaxis of P. fluorescens and A. chroococcum towards roots and their exudates is one of the several steps in the interaction process between bacteria and vesicular-arbuscular mycorrhizal roots. PMID:19719591

  18. On the longevity of desert plants and the production of new fine roots

    NASA Astrophysics Data System (ADS)

    Vargas, R.; Czimczik, C. I.; Bullock, S.; Xu, X.; Djuricin, S.

    2012-12-01

    There is evidence that some plants in arid regions can live for several hundreds of years suggesting a strong resilience to climate variability including drought events. Therefore, an important question is: Which are the physiological mechanisms of survival that are present in long-lived plants? Recent studies have shown that plants are able to store nonstructural carbon (NSC) for several years and then allocate them for production of new structures such as fine roots. We established an experiment to measure the radiocarbon age of new fine roots of desert plants between 150 and 400 years old. The study site was located at the Central Desert of Baja California, Mexico and included individuals of Brahea armata, Washingtonia robusta, and Pachycereus pringlei. Our results showed that on average all the plant species were able to use stored old carbon for production of new fine roots. These results suggest that NSC pools are important in determining belowground responses of long-lived desert plants.

  19. Increased expression of six ZIP family genes by zinc (Zn) deficiency is associated with enhanced uptake and root-to-shoot translocation of Zn in barley (Hordeum vulgare).

    PubMed

    Tiong, Jingwen; McDonald, Glenn; Genc, Yusuf; Shirley, Neil; Langridge, Peter; Huang, Chun Y

    2015-09-01

    Low zinc (Zn) in soils reduces yield and grain Zn content. Regulation of ZRT/IRT-like protein (ZIP) family genes is a major mechanism in plant adaptation to low and fluctuating Zn in soil. Although several Zn deficiency-inducible ZIP genes are identified in cereals, there has been no systematic study on the association of Zn deficiency-induced uptake and root-to-shoot translocation with expression of ZIP family genes. We measured Zn deficiency-induced uptake and root-to-shoot translocation of Zn in barley (Hordeum vulgare) plants by resupplying 0.5 μM Zn, and quantified the transcripts of thirteen HvZIP genes. Subcellular localization and tissue-specific expression were also determined for Zn deficiency-inducible HvZIP genes. Zn deficiency enhanced the capacity of uptake and root-to-shoot translocation of Zn, and sustained the enhanced capacity for 6 d after Zn resupply. Six HvZIP genes were highly induced in roots of Zn-deficient plants, and their proteins were localized in the plasma membrane. Tissue-specific expression in roots supports their roles in uptake and root-to-shoot translocation of Zn under low Zn conditions. Our results provide a comprehensive view on the physiological roles of ZIP genes in plant adaptation to low and fluctuating Zn in soil, and pave the way for development of new strategies to improve Zn-deficiency tolerance and biofortification in cereals. PMID:25904503

  20. Cytosolic Ca(2+) Signals Enhance the Vacuolar Ion Conductivity of Bulging Arabidopsis Root Hair Cells.

    PubMed

    Wang, Yi; Dindas, Julian; Rienmüller, Florian; Krebs, Melanie; Waadt, Rainer; Schumacher, Karin; Wu, Wei-Hua; Hedrich, Rainer; Roelfsema, M Rob G

    2015-11-01

    Plant cell expansion depends on the uptake of solutes across the plasma membrane and their storage within the vacuole. In contrast to the well-studied plasma membrane, little is known about the regulation of ion transport at the vacuolar membrane. We therefore established an experimental approach to study vacuolar ion transport in intact Arabidopsis root cells, with multi-barreled microelectrodes. The subcellular position of electrodes was detected by imaging current-injected fluorescent dyes. Comparison of measurements with electrodes in the cytosol and vacuole revealed an average vacuolar membrane potential of -31 mV. Voltage clamp recordings of single vacuoles resolved the activity of voltage-independent and slowly deactivating channels. In bulging root hairs that express the Ca(2+) sensor R-GECO1, rapid elevation of the cytosolic Ca(2+) concentration was observed, after impalement with microelectrodes, or injection of the Ca(2+) chelator BAPTA. Elevation of the cytosolic Ca(2+) level stimulated the activity of voltage-independent channels in the vacuolar membrane. Likewise, the vacuolar ion conductance was enhanced during a sudden increase of the cytosolic Ca(2+) level in cells injected with fluorescent Ca(2+) indicator FURA-2. These data thus show that cytosolic Ca(2+) signals can rapidly activate vacuolar ion channels, which may prevent rupture of the vacuolar membrane, when facing mechanical forces. PMID:26232520

  1. Soil-to-plant halogens transfer studies 1. Root uptake of radioiodine by plants.

    PubMed

    Kashparov, V; Colle, C; Zvarich, S; Yoschenko, V; Levchuk, S; Lundin, S

    2005-01-01

    Long-term controlled experiments under natural conditions in the field have been carried out in the Chernobyl Exclusion zone in order to determine the parameters governing radioiodine transfer to plants from four types of soils (podzoluvisol, greyzem and typical and meadow chernozem) homogeneously contaminated in the 20-cm upper layer with an addition of (125)I. An absence of (125)I depletion in arable soil layers due to volatilization was noted up to one year after contamination. During one year, depletion due to the vertical migration of radioiodine from the arable layer of each of the soils did not exceed 4% of the total (125)I content. Radioiodine concentration ratios (CR) were obtained in radish roots, lettuce leaves, bean pods, and wheat grain and straw. The highest CR values were observed in podzoluvisol: 0.01-0.03 for radish roots and lettuce leaves, 0.003-0.004 for bean pods and 0.001 for wheat grains. In the other three soils, these values were one order of magnitude lower. The parameters relating to changes in radioiodine bioavailability were determined, based on the contamination dynamics of plants in field conditions. PMID:15603907

  2. The tropic response of plant roots to oxygen: oxytropism in Pisum sativum L

    NASA Technical Reports Server (NTRS)

    Porterfield, D. M.; Musgrave, M. E.

    1998-01-01

    Plant roots are known to orient growth through the soil by gravitropism, hydrotropism, and thigmotropism. Recent observations of plant roots that developed in a microgravity environment in space suggested that plant roots may also orient their growth toward oxygen (oxytropism). Using garden pea (Pisum sativum L. cv. Weibul's Apollo) and an agravitropic mutant (cv. Ageotropum), root oxytropism was studied in the controlled environment of a microrhizotron. A series of channels in the microrhizotron allowed establishment of an oxygen gradient of 0.8 mmol mol-1 mm-1. Curvature of seedling roots was determined prior to freezing the roots for subsequent spectrophotometric determinations of alcohol dehydrogenase activity. Oxytropic curvature was observed all along the gradient in both cultivars of pea. The normal gravitropic cultivar showed a maximal curvature of 45 degrees after 48 h, while the agravitropic mutant curved to 90 degrees. In each cultivar, the amount of curvature declined as the oxygen concentration decreased, and was linearly related to the root elongation rate. Since oxytropic curvature occurred in roots exposed to oxygen concentrations that were not low enough to induce the hypoxically responsive protein alcohol dehydrogenase, we suspect that the oxygen sensor associated with oxytropism does not control the induction of hypoxic metabolism. Our results indicate that oxygen can play a critical role in determining root orientation as well as impacting root metabolic status. Oxytropism allows roots to avoid oxygen-deprived soil strata and may also be the basis of an auto-avoidance mechanism, decreasing the competition between roots for water and nutrients as well as oxygen.

  3. The tropic response of plant roots to oxygen: oxytropism in Pisum sativum L.

    PubMed

    Porterfield, D M; Musgrave, M E

    1998-09-01

    Plant roots are known to orient growth through the soil by gravitropism, hydrotropism, and thigmotropism. Recent observations of plant roots that developed in a microgravity environment in space suggested that plant roots may also orient their growth toward oxygen (oxytropism). Using garden pea (Pisum sativum L. cv. Weibul's Apollo) and an agravitropic mutant (cv. Ageotropum), root oxytropism was studied in the controlled environment of a microrhizotron. A series of channels in the microrhizotron allowed establishment of an oxygen gradient of 0.8 mmol mol-1 mm-1. Curvature of seedling roots was determined prior to freezing the roots for subsequent spectrophotometric determinations of alcohol dehydrogenase activity. Oxytropic curvature was observed all along the gradient in both cultivars of pea. The normal gravitropic cultivar showed a maximal curvature of 45 degrees after 48 h, while the agravitropic mutant curved to 90 degrees. In each cultivar, the amount of curvature declined as the oxygen concentration decreased, and was linearly related to the root elongation rate. Since oxytropic curvature occurred in roots exposed to oxygen concentrations that were not low enough to induce the hypoxically responsive protein alcohol dehydrogenase, we suspect that the oxygen sensor associated with oxytropism does not control the induction of hypoxic metabolism. Our results indicate that oxygen can play a critical role in determining root orientation as well as impacting root metabolic status. Oxytropism allows roots to avoid oxygen-deprived soil strata and may also be the basis of an auto-avoidance mechanism, decreasing the competition between roots for water and nutrients as well as oxygen. PMID:11536884

  4. Root signals and stomatal closure in relation to photosynthesis, chlorophyll a fluorescence and adventitious rooting of flooded tomato plants

    PubMed Central

    Else, Mark A.; Janowiak, Franciszek; Atkinson, Christopher J.; Jackson, Michael B.

    2009-01-01

    Background and Aims An investigation was carried out to determine whether stomatal closure in flooded tomato plants (Solanum lycopersicum) results from decreased leaf water potentials (ψL), decreased photosynthetic capacity and attendant increases in internal CO2 (Ci) or from losses of root function such as cytokinin and gibberellin export. Methods Pot-grown plants were flooded when 1 month old. Leaf conductance was measured by diffusion porometry, the efficiency of photosystem II (PSII) was estimated by fluorimetry, and infrared gas analysis was used to determine Ci and related parameters. Key Results Flooding starting in the morning closed the stomata and increased ψL after a short-lived depression of ψL. The pattern of closure remained unchanged when ψ`L depression was avoided by starting flooding at the end rather than at the start of the photoperiod. Raising external CO2 concentrations by 100 µmol mol−1 also closed stomata rapidly. Five chlorophyll fluorescence parameters [Fq′/Fm′, Fq′/Fv′, Fv′/Fm′, non-photochemical quenching (NPQ) and Fv/Fm] were affected by flooding within 12–36 h and changes were linked to decreased Ci. Closing stomata by applying abscisic acid or increasing external CO2 substantially reproduced the effects of flooding on chlorophyll fluorescence. The presence of well-aerated adventitious roots partially inhibited stomatal closure of flooded plants. Allowing adventitious roots to form on plants flooded for >3 d promoted some stomatal re-opening. This effect of adventitious roots was not reproduced by foliar applications of benzyl adenine and gibberellic acid. Conclusions Stomata of flooded plants did not close in response to short-lived decreases in ψL or to increased Ci resulting from impaired PSII photochemistry. Instead, stomatal closure depressed Ci and this in turn largely explained subsequent changes in chlorophyll fluorescence parameters. Stomatal opening was promoted by the presence of well

  5. Mapping Soil Carbon from Cradle to Grave: C Transformations of Root Exudates and Plant Litter

    NASA Astrophysics Data System (ADS)

    Pett-Ridge, J.; Keiluweit, M.; Nuccio, E.; Bougoure, J.; Weber, P. K.; Brodie, E.; Mayali, X.; Shi, S.; Hwang, M.; Thelen, M.; Firestone, M.; Kleber, M.; Nico, P. S.

    2013-12-01

    Carbon cycling in the rhizosphere is a nexus of biophysical interactions between plant roots, microorganisms, and the soil organo-mineral matrix. Plant roots provide 30-40% of soil organic C inputs, accelerate the rate of organic matter mineralization by ~10X, and support an active microhabitat for microbial transformation of soil C. Our research on how roots influence decomposition of soil organic matter in both simplified and complex microcosms uses geochemical characterization, molecular microbiology, isotope tracing, metabolomics and novel imaging approaches (';ChipSIP' and ';STXM-SIMS') to trace the fate of isotopically labelled root exudates and plant tissues. Our previous work suggests root exudates drive O2 limitation, alter metal chemistry and mineralogy, and influence the availability of SOM. Our most recent experiments using synthetic rhizospheres were designed to identify the role of root exudates on ligno-cellulose decomposition in soils. Cultures of 13C/15N-labeled single plant cells (lignin-rich tracheary elements) were added to rhizosphere microcosm soils, and their decomposition followed under the influence of different root exudates using the dual imaging approach ';STXM-SIMS'. Using this combination of X-ray spectromicroscopy and NanoSIMS, we imaged the deconstruction of 13C/15N-labeled ligno-cellulose in situ, and mapped associations of plant cell-derived decomposition products with specific soil minerals. We've also looked at microbial community function in the more complex rhizospheres surrounding roots of the annual grass Avena fatua. Using an isotope array that allows us to follow root C into bacterial, fungal, and microfaunal communities, we tracked the movement of 13C from labeled exudates and 15N from labeled root litter into the soil microbial community. Our results indicate that the microbial communities involved in litter decomposition differ in rhizosphere versus bulk soils, which may have implications for carbon stabilization in soil.

  6. Clitoria ternatea root extract enhances acetylcholine content in rat hippocampus.

    PubMed

    Rai, K S; Murthy, K D; Karanth, K S; Nalini, K; Rao, M S; Srinivasan, K K

    2002-12-01

    Treatment with 100 mg/kg of Clitoria ternatea aqueous root extract (CTR), for 30 days in neonatal and young adult age groups of rat, significantly increased acetylcholine (ACh) content in their hippocampi as compared to age matched controls. Increase in ACh content in their hippocampus may be the neurochemical basis for their improved learning and memory. PMID:12490229

  7. Chromium toxicity tolerance of Solanum nigrum L. and Parthenium hysterophorus L. plants with reference to ion pattern, antioxidation activity and root exudation.

    PubMed

    UdDin, Islam; Bano, Asghari; Masood, Sajid

    2015-03-01

    Chromium (Cr), being a highly toxic metal, adversely affects the mineral uptake and metabolic processes in plants when present in excess. The current study was aimed at investigating the Cr accumulation in various plant tissues and its relation to the antioxidation activity and root exudation. Plants were grown in soil spiked with different concentrations of Cr for three weeks in pots and analysed for different growth, antioxidants and ion attributes. Furthermore, plants treated with different concentrations of Cr in pots were shifted to rhizobox-like system for 48h and organic acids were monitored in the mucilage dissolved from the plant root surface, mirroring rhizospheric solution. The results revealed that the Cr application at 1mM increased the shoot fresh and dry weight and root dry weight of Solanum nigrum, whereas the opposite was observed for Parthenium hysterophorus when compared with lower levels of Cr (0.5mM) or control treatment. In both plant species, Cr and Cl concentrations were increased while Ca, Mg and K concentrations in root, shoot and root exudates were decreased with increasing levels of Cr. Higher levels of Cr treatments enhanced the activities of SOD, POD and proline content in leaves of S. nigrum, whereas lower levels of Cr treatment were found to have stimulatory effects in P. hysterophorus. P. hysterophorus exhibited highest exudation of organic acid contents. With increasing levels of Cr treatments, citric acid concentration in root exudates increased by 35% and 44% in S. nigrum, whereas 20% and 76% in P. hysterophorus. Cr toxicity was responsible for the shoot growth reduction of S. nigrum and P. hysterophorus, however, shoot growth response was different at different levels of applied Cr. Consequently, Cr stress negatively altered the plant physiology and biochemistry. However, the enhanced antioxidant production, Cl uptake and root exudation are the physiological and biochemical indicators for the plant adaptations in biotic systems

  8. Effects of Compost on Colonization of Roots of Plants Grown in Metalliferous Mine Tailings, as Examined by Fluorescence In Situ Hybridization▿

    PubMed Central

    Iverson, Sadie L.; Maier, Raina M.

    2009-01-01

    The relationship between compost amendment, plant biomass produced, and bacterial root colonization as measured by fluorescence in situ hybridization was examined following plant growth in mine tailings. Mine tailings can remain devoid of vegetation for decades after deposition due to a combination of factors that include heavy metal toxicity, low pH, poor substrate structure and water-holding capacity, and a severely impacted heterotrophic microbial community. Research has shown that plant establishment, a desired remedial objective to reduce eolian and water erosion of such tailings, is enhanced by organic matter amendment and is correlated with significant increases in rhizosphere populations of neutrophilic heterotrophic bacteria. Results show that for the acidic metalliferous tailings tested in this study, compost amendment was associated with significantly increased bacterial colonization of roots and increased production of plant biomass. In contrast, for a Vinton control soil, increased compost had no effect on root colonization and resulted only in increased plant biomass at high levels of compost amendment. These data suggest that the positive association between compost amendment and root colonization is important in the stressed mine tailings environment where root colonization may enhance both microbial and plant survival and growth. PMID:19047384

  9. Iron Oxide and Titanium Dioxide Nanoparticle Effects on Plant Performance and Root Associated Microbes.

    PubMed

    Burke, David J; Pietrasiak, Nicole; Situ, Shu F; Abenojar, Eric C; Porche, Mya; Kraj, Pawel; Lakliang, Yutthana; Samia, Anna Cristina S

    2015-01-01

    In this study, we investigated the effect of positively and negatively charged Fe₃O₄ and TiO₂ nanoparticles (NPs) on the growth of soybean plants (Glycine max.) and their root associated soil microbes. Soybean plants were grown in a greenhouse for six weeks after application of different amounts of NPs, and plant growth and nutrient content were examined. Roots were analyzed for colonization by arbuscular mycorrhizal (AM) fungi and nodule-forming nitrogen fixing bacteria using DNA-based techniques. We found that plant growth was significantly lower with the application of TiO₂ as compared to Fe₃O₄ NPs. The leaf carbon was also marginally significant lower in plants treated with TiO₂ NPs; however, leaf phosphorus was reduced in plants treated with Fe₃O₄. We found no effects of NP type, concentration, or charge on the community structure of either rhizobia or AM fungi colonizing plant roots. However, the charge of the Fe₃O₄ NPs affected both colonization of the root system by rhizobia as well as leaf phosphorus content. Our results indicate that the type of NP can affect plant growth and nutrient content in an agriculturally important crop species, and that the charge of these particles influences the colonization of the root system by nitrogen-fixing bacteria. PMID:26445042

  10. Iron Oxide and Titanium Dioxide Nanoparticle Effects on Plant Performance and Root Associated Microbes

    PubMed Central

    Burke, David J.; Pietrasiak, Nicole; Situ, Shu F.; Abenojar, Eric C.; Porche, Mya; Kraj, Pawel; Lakliang, Yutthana; Samia, Anna Cristina S.

    2015-01-01

    In this study, we investigated the effect of positively and negatively charged Fe3O4 and TiO2 nanoparticles (NPs) on the growth of soybean plants (Glycine max.) and their root associated soil microbes. Soybean plants were grown in a greenhouse for six weeks after application of different amounts of NPs, and plant growth and nutrient content were examined. Roots were analyzed for colonization by arbuscular mycorrhizal (AM) fungi and nodule-forming nitrogen fixing bacteria using DNA-based techniques. We found that plant growth was significantly lower with the application of TiO2 as compared to Fe3O4 NPs. The leaf carbon was also marginally significant lower in plants treated with TiO2 NPs; however, leaf phosphorus was reduced in plants treated with Fe3O4. We found no effects of NP type, concentration, or charge on the community structure of either rhizobia or AM fungi colonizing plant roots. However, the charge of the Fe3O4 NPs affected both colonization of the root system by rhizobia as well as leaf phosphorus content. Our results indicate that the type of NP can affect plant growth and nutrient content in an agriculturally important crop species, and that the charge of these particles influences the colonization of the root system by nitrogen-fixing bacteria. PMID:26445042

  11. Root strength of tropical plants - An investigation in the Western Ghats of Kerala, India

    NASA Astrophysics Data System (ADS)

    Lukose Kuriakose, S.; van Beek, L. P. H.; van Westen, C. J.

    2009-04-01

    Earlier research on debris flows in the Tikovil River basin of the Western Ghats concluded that root cohesion is significant in maintaining the overall stability of the region. In this paper we present the most recent results (December 2008) of root tensile strength tests conducted on nine species of plants that are commonly found in the region. They are 1) Rubber (Hevea Brasiliensis), 2) Coconut Palm (Cocos nucifera), 3) Jackfruit trees (Artocarpus heterophyllus), 4) Teak (Tectona grandis), 5) Mango trees (Mangifera indica), 6) Lemon grass (Cymbopogon citratus), 7) A variety of Tamarind (Garcinia gummigutta), 8) Coffee (Coffea Arabica) and Tea (Camellia sinensis). About 1500 samples were collected of which only 380 could be tested (in the laboratory) due to breakage of roots during the tests. In the successful tests roots failed in tension. Roots having diameters between 2 mm and 12 mm were tested. Each sample tested has a length of 15 cm. Results indicate that the roots of Coffee, Tamarind, Lemon grass and Jackfruit are the strongest of the nine plant types tested whereas Tea and Teak plants had the most fragile roots. Coconut roots behaved atypical to the others, as the bark of the roots was crushed and slipped from the clamp when tested whereas its internal fiber was the strongest of all tested. Root tensile strength decreases with increasing diameters, Rubber showing more ductile behaviour than Coffee and Tamarind that behaved more brittle, root tensile strength increasing exponentially for finer roots. Teak and Tea showed almost a constant root tensile strength over the range of diameters tested and little variability. Jack fruit and mango trees showed the largest variability, which may be explained by the presence of root nodules, preventing the derivation of an unequivocal relationship between root diameters and tensile strength. This results in uncertainty of root strength estimates that are applicable. These results provide important information to

  12. Soil Penetration by Earthworms and Plant Roots--Mechanical Energetics of Bioturbation of Compacted Soils.

    PubMed

    Ruiz, Siul; Or, Dani; Schymanski, Stanislaus J

    2015-01-01

    We quantify mechanical processes common to soil penetration by earthworms and growing plant roots, including the energetic requirements for soil plastic displacement. The basic mechanical model considers cavity expansion into a plastic wet soil involving wedging by root tips or earthworms via cone-like penetration followed by cavity expansion due to pressurized earthworm hydroskeleton or root radial growth. The mechanical stresses and resulting soil strains determine the mechanical energy required for bioturbation under different soil hydro-mechanical conditions for a realistic range of root/earthworm geometries. Modeling results suggest that higher soil water content and reduced clay content reduce the strain energy required for soil penetration. The critical earthworm or root pressure increases with increased diameter of root or earthworm, however, results are insensitive to the cone apex (shape of the tip). The invested mechanical energy per unit length increase with increasing earthworm and plant root diameters, whereas mechanical energy per unit of displaced soil volume decreases with larger diameters. The study provides a quantitative framework for estimating energy requirements for soil penetration work done by earthworms and plant roots, and delineates intrinsic and external mechanical limits for bioturbation processes. Estimated energy requirements for earthworm biopore networks are linked to consumption of soil organic matter and suggest that earthworm populations are likely to consume a significant fraction of ecosystem net primary production to sustain their subterranean activities. PMID:26087130

  13. PLANT MICROBIOME. Salicylic acid modulates colonization of the root microbiome by specific bacterial taxa.

    PubMed

    Lebeis, Sarah L; Paredes, Sur Herrera; Lundberg, Derek S; Breakfield, Natalie; Gehring, Jase; McDonald, Meredith; Malfatti, Stephanie; Glavina del Rio, Tijana; Jones, Corbin D; Tringe, Susannah G; Dangl, Jeffery L

    2015-08-21

    Immune systems distinguish "self" from "nonself" to maintain homeostasis and must differentially gate access to allow colonization by potentially beneficial, nonpathogenic microbes. Plant roots grow within extremely diverse soil microbial communities but assemble a taxonomically limited root-associated microbiome. We grew isogenic Arabidopsis thaliana mutants with altered immune systems in a wild soil and also in recolonization experiments with a synthetic bacterial community. We established that biosynthesis of, and signaling dependent on, the foliar defense phytohormone salicylic acid is required to assemble a normal root microbiome. Salicylic acid modulates colonization of the root by specific bacterial families. Thus, plant immune signaling drives selection from the available microbial communities to sculpt the root microbiome. PMID:26184915

  14. Improved plant resistance to drought is promoted by the root-associated microbiome as a water stress-dependent trait.

    PubMed

    Rolli, Eleonora; Marasco, Ramona; Vigani, Gianpiero; Ettoumi, Besma; Mapelli, Francesca; Deangelis, Maria Laura; Gandolfi, Claudio; Casati, Enrico; Previtali, Franco; Gerbino, Roberto; Pierotti Cei, Fabio; Borin, Sara; Sorlini, Claudia; Zocchi, Graziano; Daffonchio, Daniele

    2015-02-01

    Although drought is an increasing problem in agriculture, the contribution of the root-associated bacterial microbiome to plant adaptation to water stress is poorly studied. We investigated if the culturable bacterial microbiome associated with five grapevine rootstocks and the grapevine cultivar Barbera may enhance plant growth under drought stress. Eight isolates, over 510 strains, were tested in vivo for their capacity to support grapevine growth under water stress. The selected strains exhibited a vast array of plant growth promoting (PGP) traits, and confocal microscopy observation of gfp-labelled Acinetobacter and Pseudomonas isolates showed their ability to adhere and colonize both the Arabidopsis and grapevine rhizoplane. Tests on pepper plants fertilized with the selected strains, under both optimal irrigation and drought conditions, showed that PGP activity was a stress-dependent and not a per se feature of the strains. The isolates were capable of increasing shoot and leaf biomass, shoot length, and photosynthetic activity of drought-challenged grapevines, with an enhanced effect in drought-sensitive rootstock. Three isolates were further assayed for PGP capacity under outdoor conditions, exhibiting the ability to increase grapevine root biomass. Overall, the results indicate that PGP bacteria contribute to improve plant adaptation to drought through a water stress-induced promotion ability. PMID:24571749

  15. Effect of Soils from Six Management Systems on Root-knot Nematodes and Plant Growth in Greenhouse Assays

    PubMed Central

    Kokalis-Burelle, N.; Chellemi, D. O.; Périès, X.

    2005-01-01

    The effects of soil management systems on root-knot nematode (Meloidogyne incognita) eggs and gall incidence on tomato (Lycopersicon esculentum) and cucumber (Cucumis sativus) following tomato were evaluated. Soil was collected from a replicated field experiment in which six management systems were being assessed for vegetable production. Soil management systems were conventional production, organic production, bahiagrass (Paspalum notatum) pasture, bahiagrass: Stylosanthes (Stylosanthes guianensis) pasture, bare ground fallow, and weed fallow. Soil was collected from field plots and used in greenhouse experiments. Identification of egg-parasitic fungi and the incidence of root-knot nematode galling were assessed both on tomato and cucumber planted in the same pots following the removal of tomato plants. Organic, bare ground fallow and conventional production treatments reduced galling both on tomato and on cucumber following tomato. Although no treatment consistently enhanced egg-parasitic fungi, management system did affect egg viability and the types of fungi isolated from parasitized eggs. PMID:19262892

  16. Ascorbic Acid Enhances the Accumulation of Polycyclic Aromatic Hydrocarbons (PAHs) in Roots of Tall Fescue (Festuca arundinacea Schreb.)

    PubMed Central

    Gao, Yanzheng; Li, Hui; Gong, Shuaishuai

    2012-01-01

    Plant contamination by polycyclic aromatic hydrocarbons (PAHs) is crucial to food safety and human health. Enzyme inhibitors are commonly utilized in agriculture to control plant metabolism of organic components. This study revealed that the enzyme inhibitor ascorbic acid (AA) significantly reduced the activities of peroxidase (POD) and polyphenol oxidase (PPO), thus enhancing the potential risks of PAH contamination in tall fescue (Festuca arundinacea Schreb.). POD and PPO enzymes in vitro effectively decomposed naphthalene (NAP), phenanthrene (PHE) and anthracene (ANT). The presence of AA reduced POD and PPO activities in plants, and thus was likely responsible for enhanced PAH accumulation in tall fescue. This conclusion is supported by the significantly enhanced uptake of PHE in plants in the presence of AA, and the positive correlation between enzyme inhibition efficiencies and the rates of metabolism of PHE in tall fescue roots. This study provides a new perspective, that the common application of enzyme inhibitors in agricultural production could increase the accumulation of organic contaminants in plants, hence enhancing risks to food safety and quality. PMID:23185628

  17. Enhancement of reproductive heat tolerance in plants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The current study investigated the enhancement of plant reproductive heat tolerance through the use of a gene encoding the Arabidopsis thaliana heat shock protein 101 (AtHSP101) not normally expressed in pollen but reported to play a crucial role in vegetative thermotolerance. The Arabidopsis thali...

  18. Truffles regulate plant root morphogenesis via the production of auxin and ethylene.

    PubMed

    Splivallo, Richard; Fischer, Urs; Göbel, Cornelia; Feussner, Ivo; Karlovsky, Petr

    2009-08-01

    Truffles are symbiotic fungi that form ectomycorrhizas with plant roots. Here we present evidence that at an early stage of the interaction, i.e. prior to physical contact, mycelia of the white truffle Tuber borchii and the black truffle Tuber melanopsorum induce alterations in root morphology of the host Cistus incanus and the nonhost Arabidopsis (Arabidopsis thaliana; i.e. primary root shortening, lateral root formation, root hair stimulation). This was most likely due to the production of indole-3-acetic acid (IAA) and ethylene by the mycelium. Application of a mixture of the ethylene precursor 1-aminocyclopropane-1-carboxylic acid and IAA fully mimicked the root morphology induced by the mycelium for both host and nonhost plants. Application of the single hormones only partially mimicked it. Furthermore, primary root growth was not inhibited in the Arabidopsis auxin transport mutant aux1-7 by truffle metabolites while root branching was less effected in the ethylene-insensitive mutant ein2-LH. The double mutant aux1-7;ein2-LH displayed reduced sensitivity to fungus-induced primary root shortening and branching. In agreement with the signaling nature of truffle metabolites, increased expression of the auxin response reporter DR5GFP in Arabidopsis root meristems subjected to the mycelium could be observed, confirming that truffles modify the endogenous hormonal balance of plants. Last, we demonstrate that truffles synthesize ethylene from l-methionine probably through the alpha-keto-gamma-(methylthio)butyric acid pathway. Taken together, these results establish the central role of IAA and ethylene as signal molecules in truffle/plant interactions. PMID:19535471

  19. Root physiological adaptations involved in enhancing P assimilation in mining and non-mining ecotypes of Polygonum hydropiper grown under organic P media

    PubMed Central

    Ye, Daihua; Li, Tingxuan; Zheng, Zicheng; Zhang, Xizhou; Chen, Guangdeng; Yu, Haiying

    2015-01-01

    It is important to seek out plant species, high in phosphorus (P) uptake, for phytoremediation of P-enriched environments with a large amount of organic P (Po). P assimilation characteristics and the related mechanisms of Polygonum hydropiper were investigated in hydroponic media containing various concentrations of Po (1–8 mmol L-1) supplied as phytate. The mining ecotype (ME) showed significantly higher biomass in both shoots and roots compared to the non-mining ecotype (NME) at 4, 6, and 8 m mol L-1. Shoot P content of both ecotypes increased up to 4 mmol L-1 while root P content increased continually up to 8 mmol L-1 for the ME and up to 6 mmol L-1 for the NME. Root P content of the ME exceeded 1% dry weight under 6 and 8 mmol L-1. The ME had significantly higher P accumulation in both shoots and roots compared to the NME supplied with 6 and 8 mmol L-1. The ME showed higher total root length, specific root length, root surface area, root volume, and displayed significantly greater root length, root surface area, and root volume of lateral roots compared to the NME grown in all Po treatments. Average diameter of lateral roots was 0.17–19 mm for the ME and 0.18–0.21 mm for the NME. Greater acid phosphatase and phytase activities were observed in the ME grown under different levels of Po relative to the NME. This indicated fine root morphology, enhanced acid phosphatase and phytase activities might be adaptations to high Po media. Results from this study establish that the ME of P. hydropiper is capable of assimilating P from Po media and is a potential material for phytoremediation of polluted area with high Po. PMID:25699065

  20. Host genotype and age shape the leaf and root microbiomes of a wild perennial plant.

    PubMed

    Wagner, Maggie R; Lundberg, Derek S; Del Rio, Tijana G; Tringe, Susannah G; Dangl, Jeffery L; Mitchell-Olds, Thomas

    2016-01-01

    Bacteria living on and in leaves and roots influence many aspects of plant health, so the extent of a plant's genetic control over its microbiota is of great interest to crop breeders and evolutionary biologists. Laboratory-based studies, because they poorly simulate true environmental heterogeneity, may misestimate or totally miss the influence of certain host genes on the microbiome. Here we report a large-scale field experiment to disentangle the effects of genotype, environment, age and year of harvest on bacterial communities associated with leaves and roots of Boechera stricta (Brassicaceae), a perennial wild mustard. Host genetic control of the microbiome is evident in leaves but not roots, and varies substantially among sites. Microbiome composition also shifts as plants age. Furthermore, a large proportion of leaf bacterial groups are shared with roots, suggesting inoculation from soil. Our results demonstrate how genotype-by-environment interactions contribute to the complexity of microbiome assembly in natural environments. PMID:27402057

  1. Host genotype and age shape the leaf and root microbiomes of a wild perennial plant

    PubMed Central

    Wagner, Maggie R.; Lundberg, Derek S; del Rio, Tijana G.; Tringe, Susannah G.; Dangl, Jeffery L.; Mitchell-Olds, Thomas

    2016-01-01

    Bacteria living on and in leaves and roots influence many aspects of plant health, so the extent of a plant's genetic control over its microbiota is of great interest to crop breeders and evolutionary biologists. Laboratory-based studies, because they poorly simulate true environmental heterogeneity, may misestimate or totally miss the influence of certain host genes on the microbiome. Here we report a large-scale field experiment to disentangle the effects of genotype, environment, age and year of harvest on bacterial communities associated with leaves and roots of Boechera stricta (Brassicaceae), a perennial wild mustard. Host genetic control of the microbiome is evident in leaves but not roots, and varies substantially among sites. Microbiome composition also shifts as plants age. Furthermore, a large proportion of leaf bacterial groups are shared with roots, suggesting inoculation from soil. Our results demonstrate how genotype-by-environment interactions contribute to the complexity of microbiome assembly in natural environments. PMID:27402057

  2. Fungal root endophyte associations of plants endemic to the Pamir Alay Mountains of Central Asia.

    PubMed

    Zubek, Szymon; Nobis, Marcin; Błaszkowski, Janusz; Mleczko, Piotr; Nowak, Arkadiusz

    2011-06-01

    The fungal root endophyte associations of 16 species from 12 families of plants endemic to the Pamir Alay Mountains of Central Asia are presented. The plants and soil samples were collected in Zeravshan and Hissar ranges within the central Pamir Alay mountain system. Colonization by arbuscular mycorrhizal fungi (AMF) was found in 15 plant species; in 8 species it was of the Arum type and in 4 of the Paris type, while 3 taxa revealed intermediate arbuscular mycorrhiza (AM) morphology. AMF colonization was found to be absent only in Matthiola integrifolia, the representative of the Brassicaceae family. The AM status and morphology are reported for the first time for all the species analyzed and for the genera Asyneuma, Clementsia, and Eremostachys. Mycelia of dark septate endophytes (DSE) accompanied the AMF colonization in ten plant species. The frequency of DSE occurrence in the roots was low in all the plants, with the exception of Spiraea baldschuanica. However, in the case of both low and higher occurrence, the percentage of DSE root colonization was low. Moreover, the sporangia of Olpidium spp. were sporadically found inside the root epidermal cells of three plant species. Seven AMF species (Glomeromycota) found in the trap cultures established with soils surrounding roots of the plants being studied were reported for the first time from this region of Asia. Our results provide information that might well be of use to the conservation and restoration programmes of these valuable plant species. The potential application of beneficial root-inhabiting fungi in active plant protection projects of rare, endemic and endangered plants is discussed. PMID:22207783

  3. High temperatures limit plant growth but hasten flowering in root chicory (Cichorium intybus) independently of vernalisation.

    PubMed

    Mathieu, Anne-Sophie; Lutts, Stanley; Vandoorne, Bertrand; Descamps, Christophe; Périlleux, Claire; Dielen, Vincent; Van Herck, Jean-Claude; Quinet, Muriel

    2014-01-15

    An increase in mean and extreme summer temperatures is expected as a consequence of climate changes and this might have an impact on plant development in numerous species. Root chicory (Cichorium intybus L.) is a major crop in northern Europe, and it is cultivated as a source of inulin. This polysaccharide is stored in the tap root during the first growing season when the plant grows as a leafy rosette, whereas bolting and flowering occur in the second year after winter vernalisation. The impact of heat stress on plant phenology, water status, photosynthesis-related parameters, and inulin content was studied in the field and under controlled phytotron conditions. In the field, plants of the Crescendo cultivar were cultivated under a closed plastic-panelled greenhouse to investigate heat-stress conditions, while the control plants were shielded with a similar, but open, structure. In the phytotrons, the Crescendo and Fredonia cultivars were exposed to high temperatures (35°C day/28°C night) and compared to control conditions (17°C) over 10 weeks. In the field, heat reduced the root weight, the inulin content of the root and its degree of polymerisation in non-bolting plants. Flowering was observed in 12% of the heat stressed plants during the first growing season in the field. In the phytotron, the heat stress increased the total number of leaves per plant, but reduced the mean leaf area. Photosynthesis efficiency was increased in these plants, whereas osmotic potential was decreased. High temperature was also found to induced flowering of up to 50% of these plants, especially for the Fredonia cultivar. In conclusion, high temperatures induced a reduction in the growth of root chicory, although photosynthesis is not affected. Flowering was also induced, which indicates that high temperatures can partly substitute for the vernalisation requirement for the flowering of root chicory. PMID:24331425

  4. Characterising root density of peach trees in a semi-arid Chernozem to increase plant density

    NASA Astrophysics Data System (ADS)

    Paltineanu, Cristian; Septar, Leinar; Gavat, Corina; Chitu, Emil; Oprita, Alexandru; Moale, Cristina; Calciu, Irina; Vizitiu, Olga; Lamureanu, Gheorghe

    2016-01-01

    The available information on root system in fully mature peach orchards in semi-arid regions is insufficient. This paper presents a study on the root system density in an irrigated peach orchard from Dobrogea, Romania, using the trench technique. The old orchard has clean cultivation in inter-row and in-row. The objectives of the study were to: test the hypothesis that the roots of fully mature peach trees occupy the whole soil volume; find out if root repulsive effect of adjacent plants occurred for the rootstocks and soil conditions; find relationships between root system and soil properties and analyse soil state trend. Some soil physical properties were significantly deteriorated in inter-row versus in-row, mainly due to soil compaction induced by technological traffic. Density of total roots was higher in-row than inter-row, but the differences were not significant. Root density decreased more intensely with soil depth than with distance from tree trunks. Root density correlated with some soil properties. No repulsive effect of the roots of adjacent peach trees was noted. The decrease of root density with distance from trunk can be used in optimising tree arrangement. The conclusions could also be used in countries with similar growth conditions.

  5. Modelling metal accumulation using humic acid as a surrogate for plant roots.

    PubMed

    Le, T T Yen; Swartjes, Frank; Römkens, Paul; Groenenberg, Jan E; Wang, Peng; Lofts, Stephen; Hendriks, A Jan

    2015-04-01

    Metal accumulation in roots was modelled with WHAM VII using humic acid (HA) as a surrogate for root surface. Metal accumulation was simulated as a function of computed metal binding to HA, with a correction term (E(HA)) to account for the differences in binding site density between HA and root surface. The approach was able to model metal accumulation in roots to within one order of magnitude for 95% of the data points. Total concentrations of Mn in roots of Vigna unguiculata, total concentrations of Ni, Zn, Cu and Cd in roots of Pisum sativum, as well as internalized concentrations of Cd, Ni, Pb and Zn in roots of Lolium perenne, were significantly correlated to the computed metal binding to HA. The method was less successful at modelling metal accumulation at low concentrations and in soil experiments. Measured concentrations of Cu internalized in L. perenne roots were not related to Cu binding to HA modelled and deviated from the predictions by over one order of magnitude. The results indicate that metal uptake by roots may under certain conditions be influenced by conditional physiological processes that cannot simulated by geochemical equilibrium. Processes occurring in chronic exposure of plants grown in soil to metals at low concentrations complicate the relationship between computed metal binding to HA and measured metal accumulation in roots. PMID:25482978

  6. Effect of Mulch Surface Color on Root-knot of Tomato Grown in Simulated Planting Beds.

    PubMed

    Fortnum, B A; Kasperbauer, M J; Decoteau, D R

    2000-03-01

    The effect of different-colored polyethylene mulches on quantity and spectra of reflected light, plant morphology, and root-knot disease was studied in tomato (Lycopersicon esculentum) grown in simulated planting beds. Tomato plants were inoculated with Meloidogyne incognita at initial populations (Pi) of 0, 1,000, 10,000, or 50,000 eggs/plant, and grown in a greenhouse for 50 days over white, red, or black mulch. Soil temperature was kept constant among the mulch treatments by placing an insulation barrier between the colored mulch and the soil surface. Soil temperature varied less than 0.5 degrees C between soil chambers at solar noon. Tomatoes grown over white mulch received more reflected photosynthetic light and had greater shoot weights (27%), root weights (32%), and leaf area (20%) than plants grown over black mulch. Plants grown over red mulch received a higher far-red-to-red ratio in the reflected light. Mulch color altered the plant's response to root-knot nematode infection by changing the distribution of mass in axillary shoots. At high Pi, axillary leaf area and leaf weight were greater in tomato grown over white mulch than when grown over red mulch. The root-gall index was lower for plants grown over white mulch than similar plants grown over red mulch. PMID:19270954

  7. Overexpressing OsPIN2 enhances aluminium internalization by elevating vesicular trafficking in rice root apex

    PubMed Central

    Wu, Daoming; Shen, Hong; Yokawa, Ken; Baluška, František

    2015-01-01

    Aluminium (Al) sequestration is required for internal detoxification of Al in plant cells. In this study, it was found that the rice OsPIN2 overexpression line (OX1) had significantly reduced Al content in its cell wall and increased Al concentration in cell sap only in rice root tips relative to the wild-type (WT). In comparison with WT, OX1 reduced morin staining of cytosolic Al, enhanced FM 4–64 staining of membrane vesicular trafficking in root tip sections (0–1mm), and showed morin-FM 4–64 fluorescence overlap. Recovery treatment showed that cell-wall-bound Al was internalized into vacuoles via endocytic vesicular trafficking after removal of external Al. In this process, OX1 showed a higher rate of Al internalization than WT. Brefeldin A (BFA) interfered with vesicular trafficking and resulted in inhibition of Al internalization. This inhibitory effect could be alleviated when BFA was washed out, and the process of alleviation was slower in the cells of WT than in those of OX1. Microscopic observations revealed that, upon Al exposure, numerous multilamellar endosomes were detected between the cell wall and plasma membrane in the cells of OX1. Moreover, more vesicles enriched with Al complexes accumulated in the cells of OX1 than in those of WT, and these vesicles transformed into larger structures in the cells of OX1. Taken together, the data indicate that endocytic vesicular trafficking might contribute to Al internalization, and that overexpressing OsPIN2 enhances rice Al tolerance via elevated endocytic vesicular trafficking and Al internalization. PMID:26254327

  8. Overexpressing OsPIN2 enhances aluminium internalization by elevating vesicular trafficking in rice root apex.

    PubMed

    Wu, Daoming; Shen, Hong; Yokawa, Ken; Baluška, František

    2015-11-01

    Aluminium (Al) sequestration is required for internal detoxification of Al in plant cells. In this study, it was found that the rice OsPIN2 overexpression line (OX1) had significantly reduced Al content in its cell wall and increased Al concentration in cell sap only in rice root tips relative to the wild-type (WT). In comparison with WT, OX1 reduced morin staining of cytosolic Al, enhanced FM 4-64 staining of membrane vesicular trafficking in root tip sections (0-1mm), and showed morin-FM 4-64 fluorescence overlap. Recovery treatment showed that cell-wall-bound Al was internalized into vacuoles via endocytic vesicular trafficking after removal of external Al. In this process, OX1 showed a higher rate of Al internalization than WT. Brefeldin A (BFA) interfered with vesicular trafficking and resulted in inhibition of Al internalization. This inhibitory effect could be alleviated when BFA was washed out, and the process of alleviation was slower in the cells of WT than in those of OX1. Microscopic observations revealed that, upon Al exposure, numerous multilamellar endosomes were detected between the cell wall and plasma membrane in the cells of OX1. Moreover, more vesicles enriched with Al complexes accumulated in the cells of OX1 than in those of WT, and these vesicles transformed into larger structures in the cells of OX1. Taken together, the data indicate that endocytic vesicular trafficking might contribute to Al internalization, and that overexpressing OsPIN2 enhances rice Al tolerance via elevated endocytic vesicular trafficking and Al internalization. PMID:26254327

  9. Effects of root decomposition on plant-soil feedback of early- and mid-successional plant species.

    PubMed

    Zhang, Naili; Van der Putten, Wim H; Veen, G F Ciska

    2016-10-01

    Plant-soil feedback (PSF) is an important driver of plant community dynamics. Many studies have emphasized the role of pathogens and symbiotic mutualists in PSFs; however, less is known about the contribution of decomposing litter, especially that of roots. We conducted a PSF experiment, where soils were conditioned by living early- and mid-successional grasses and forbs with and without decomposing roots of conspecific species (conditioning phase). These soils were used to test growth responses of conspecific and heterospecific plant species (feedback phase). The addition of the roots of conspecifics decreased the biomass of both early- and mid-successional plant species in the conditioning phase. In the feedback phase, root addition had positive effects on the biomass of early-successional species and neutral effects on mid-successional species, except when mid-successional grasses were grown in soils conditioned by conspecifics, where effects were negative. Biomass of early- and mid-successional forbs was generally reduced in soils conditioned by conspecifics. We conclude that root decomposition may increase short-term negative PSF effects, but that the effects can become neutral to positive over time, thereby counteracting negative components of PSF. This implies that root decomposition is a key element of PSF and needs to be included in future studies. PMID:27214646

  10. Influence of copper on root exudate patterns in some metallophytes and agricultural plants.

    PubMed

    Meier, S; Alvear, M; Borie, F; Aguilera, P; Ginocchio, R; Cornejo, P

    2012-01-01

    A hydroponic experiment was carried out to determine the root exudation patterns in two Cu-metallophytes (Oenothera picensis and Imperata condensata) and two agricultural plants (Lupinus albus and Helianthus annuus). Plants were grown in nutrient solution at increasing Cu doses (0, 0.125, 0.25, 0.5, 1 and 2mgCuL(-1)), and plant growth, root elongation, Cu accumulation and root exudates were measured. All plants showed a decrease of over 60% in root elongation at the highest Cu supply level, being O. picensis the most sensitive specie and showing the highest shoot and root Cu concentrations (116 and 2657μgCug(-1), respectively), which were six fold higher than the other species. Differences in root exudation patterns of low molecular weight organic acids were found, with extremely high amounts of succinic acid exuded by O. picensis (1049μmolg(-1)h(-1)), and citric acid by I. condensata (164μmolg(-1)h(-1)). In metallophytes, the organic acid exudation was increased even with no root elongation, meanwhile agricultural plants exuded citric acid at constant levels. Exudation of phenolic compounds was highly species-dependent, with catechin mainly exuded by I. condensata, (2.62μmolg(-1)h(-1)) cinnamic acid by O. picensis (5.08μmolg(-1)h(-1)) and coumaric acid exclusively exuded by H. annuus (13.6μmolg(-1)h(-1)) at high Cu levels. These results indicated that differences in root exudation patterns among metallophytes and agricultural plants could affect their Cu tolerance. Particularly, the higher exudation rate showed by I. condensata can be an effective exclusion mechanism to tolerate high Cu concentrations, supporting its use in Cu phytostabilization programs. PMID:21937112

  11. Roles for root iron plaque in sequestration and uptake of heavy metals and metalloids in aquatic and wetland plants.

    PubMed

    Tripathi, Rudra D; Tripathi, Preeti; Dwivedi, Sanjay; Kumar, Amit; Mishra, Aradhana; Chauhan, Puneet S; Norton, Gareth J; Nautiyal, Chandra S

    2014-10-01

    Toxic metal(loid) contamination of soil and sediment poses long term risk to soil and human health through plant-human or plant-animal-human food chain pathways. Iron plaque (IP) formation is frequent in aquatic and wetland plant species and is responsible for the sequestration of various metal(loids). The presence of IP may act as a buffer or barrier and may thus enhance or reduce the uptake of potentially phytotoxic metals and metalloids by plants. If IP acts as a barrier, then low IP producing macrophytes/aquatic plants may be better accumulators of toxic metals and may find use in constructed wetlands for remediation of pollutants, while high IP forming edible plant species could be safer for human consumption. Conversely, if IP acts as a buffer for mineral nutrients and toxic elements then those cultivars may be rich in nutrients, but may also cause toxicity. However, an ecotoxicological risk is also inevitable if IP rich macrophyte roots containing heavy metals are consumed by herbivores. In this review, we summarize the current understanding about the role of IP in metal and metalloid sequestration, uptake, and transport. Furthermore, we will address the role of root IP in Oryza sativa for arsenic (As) sequestration leading to lower grain As translocation, reducing the risk of human exposure. PMID:24925182

  12. The role of roots in the accumulation and removal of cadmium by the aquatic plant Hydrilla verticillata.

    PubMed

    He, Yan; Rui, Haiyun; Chen, Chen; Chen, Yahua; Shen, Zhenguo

    2016-07-01

    Aquatic macrophytes can absorb heavy metals either from sediments via the root system, from the water phase by leaves, or from both sources. In this study, cadmium accumulation and distribution in the aquatic plant Hydrilla verticillata were investigated, with a focus on the role of roots. Results showed that leaves of H. verticillata had a higher Cd concentration than roots when intact plants were grown in sediments and solutions containing Cd. Cadmium can significantly decrease the leaf chlorophyll content, and the leaves of intact plants with roots had lower chlorophyll contents than the leaves of detached ones without roots due to the transfer effect of roots. The majority of the Cd accumulated in leaves of H. verticillata was bound to the cell walls. When roots were submerged in a solution containing Cd, with shoots in a control solution without Cd, the Cd concentrations in leaves were considerably lower than in roots. In contrast, Cd was almost undetectable in roots when the shoots were submerged in a solution containing Cd, with roots in the control solution. Compared to the leaves and stems of detached shoots without roots, the concentrations of Cd were much higher in the leaves and stems of intact plants with roots. It is suggested that the roots of intact plants absorb Cd and transfer it to leaves and that more Cd is removed from the solution by intact plants. PMID:27023818

  13. The Root-Associated Microbial Community of the World's Highest Growing Vascular Plants.

    PubMed

    Angel, Roey; Conrad, Ralf; Dvorsky, Miroslav; Kopecky, Martin; Kotilínek, Milan; Hiiesalu, Inga; Schweingruber, Fritz; Doležal, Jiří

    2016-08-01

    Upward migration of plants to barren subnival areas is occurring worldwide due to raising ambient temperatures and glacial recession. In summer 2012, the presence of six vascular plants, growing in a single patch, was recorded at an unprecedented elevation of 6150 m.a.s.l. close to the summit of Mount Shukule II in the Western Himalayas (Ladakh, India). Whilst showing multiple signs of stress, all plants have managed to establish stable growth and persist for several years. To learn about the role of microbes in the process of plant upward migration, we analysed the root-associated microbial community of the plants (three individuals from each) using microscopy and tagged amplicon sequencing. No mycorrhizae were found on the roots, implying they are of little importance to the establishment and early growth of the plants. However, all roots were associated with a complex bacterial community, with richness and diversity estimates similar or even higher than the surrounding bare soil. Both soil and root-associated communities were dominated by members of the orders Sphingomonadales and Sphingobacteriales, which are typical for hot desert soils, but were different from communities of temperate subnival soils and typical rhizosphere communities. Despite taxonomic similarity on the order level, the plants harboured a unique set of highly dominant operational taxonomic units which were not found in the bare soil. These bacteria have been likely transported with the dispersing seeds and became part of the root-associated community following germination. The results indicate that developing soils act not only as a source of inoculation to plant roots but also possibly as a sink for plant-associated bacteria. PMID:27245598

  14. Plant roots alter microbial potential for mediation of soil organic carbon decomposition

    NASA Astrophysics Data System (ADS)

    Firestone, M.; Shi, S.; Herman, D.; He, Z.; Zhou, J.

    2014-12-01

    Plant root regulation of soil organic carbon (SOC) decomposition is a key controller of terrestrial C-cycling. Although many studies have tested possible mechanisms underlying plant "priming" of decomposition, few have investigated the microbial mediators of decomposition, which can be greatly influenced by plant activities. Here we examined effects of Avena fatua roots on decomposition of 13C-labeled root litter in a California grassland soil over two simulated growing-seasons. The presence of plant roots consistently suppressed rates of litter decomposition. Reduction of inorganic nitrogen (N) concentration in soil reduced but did not completely relieve this suppressive effect. The presence of plants significantly altered the abundance, composition and functional potential of microbial communities. Significantly higher signal intensities of genes capable of degrading low molecular weight organic compounds (e.g., glucose, formate and malate) were observed in microbial communities from planted soils, while microorganisms in unplanted soils had higher relative abundances of genes involved in degradation of some macromolecules (e.g., hemicellulose and lignin). Additionally, compared to unplanted soils, microbial communities from planted soils had higher signal intensities of proV and proW, suggesting microbial osmotic stress in planted soils. Possible mechanisms for the observed inhibition of decomposition are 1) microbes preferentially using simple substrates from root exudates and 2) soil drying by plant evapotranspiration impairing microbial activity. We propose a simple data-based model suggesting that the impacts of roots, the soil environment, and microbial community composition on decomposition processes result from impacts of these factors on the soil microbial functional gene potential.

  15. Genetic Control of Plant Root Colonization by the Biocontrol agent, Pseudomonas fluorescens

    SciTech Connect

    Cole, Benjamin J.; Fletcher, Meghan; Waters, Jordan; Wetmore, Kelly; Blow, Matthew J.; Deutschbauer, Adam M.; Dangl, Jeffry L.; Visel, Axel

    2015-03-19

    Plant growth promoting rhizobacteria (PGPR) are a critical component of plant root ecosystems. PGPR promote plant growth by solubilizing inaccessible minerals, suppressing pathogenic microorganisms in the soil, and directly stimulating growth through hormone synthesis. Pseudomonas fluorescens is a well-established PGPR isolated from wheat roots that can also colonize the root system of the model plant, Arabidopsis thaliana. We have created barcoded transposon insertion mutant libraries suitable for genome-wide transposon-mediated mutagenesis followed by sequencing (TnSeq). These libraries consist of over 105 independent insertions, collectively providing loss-of-function mutants for nearly all genes in the P.fluorescens genome. Each insertion mutant can be unambiguously identified by a randomized 20 nucleotide sequence (barcode) engineered into the transposon sequence. We used these libraries in a gnotobiotic assay to examine the colonization ability of P.fluorescens on A.thaliana roots. Taking advantage of the ability to distinguish individual colonization events using barcode sequences, we assessed the timing and microbial concentration dependence of colonization of the rhizoplane niche. These data provide direct insight into the dynamics of plant root colonization in an in vivo system and define baseline parameters for the systematic identification of the bacterial genes and molecular pathways using TnSeq assays. Having determined parameters that facilitate potential colonization of roots by thousands of independent insertion mutants in a single assay, we are currently establishing a genome-wide functional map of genes required for root colonization in P.fluorescens. Importantly, the approach developed and optimized here for P.fluorescens>A.thaliana colonization will be applicable to a wide range of plant-microbe interactions, including biofuel feedstock plants and microbes known or hypothesized to impact on biofuel-relevant traits including biomass productivity

  16. Rhizosphere priming effect on soil organic carbon decomposition under plant species differing in soil acidification and root exudation.

    PubMed

    Wang, Xiaojuan; Tang, Caixian; Severi, Julia; Butterly, Clayton R; Baldock, Jeff A

    2016-08-01

    Effects of rhizosphere properties on the rhizosphere priming effect (RPE) are unknown. This study aimed to link species variation in RPE with plant traits and rhizosphere properties. Four C3 species (chickpea, Cicer arietinum; field pea, Pisum sativum; wheat, Triticum aestivum; and white lupin, Lupinus albus) differing in soil acidification and root exudation, were grown in a C4 soil. The CO2 released from soil was trapped using a newly developed NaOH-trapping system. White lupin and wheat showed greater positive RPEs, in contrast to the negative RPE produced by chickpea. The greatest RPE of white lupin was in line with its capacity to release root exudates, whereas the negative RPE of chickpea was attributed to its great ability to acidify rhizosphere soil. The enhanced RPE of field pea at maturity might result from high nitrogen deposition and release of structural root carbon components following root senescence. Root biomass and length played a minor role in the species variation in RPE. Rhizosphere acidification was shown to be an important factor affecting the magnitude and direction of RPE. Future studies on RPE modelling and mechanistic understanding of the processes that regulate RPE should consider the effect of rhizosphere pH. PMID:27101777

  17. A Re-examination of the Root Cortex in Wetland Flowering Plants With Respect to Aerenchyma

    PubMed Central

    SEAGO, JAMES L.; MARSH, LELAND C.; STEVENS, KEVIN J.; SOUKUP, ALEŠ; VOTRUBOVÁ, OLGA; ENSTONE, DARYL E.

    2005-01-01

    • Aims We review literature and present new observations on the differences among three general patterns of aerenchyma origin and their systematic distributions among the flowering plants, and we clarify terminology on root aerenchyma. • Scope From our own previous works and some new observations, we have analysed the root cortex in 85 species of 41 families in 21 orders of flowering plants that typically grow in wetlands to determine the characteristic patterns of aerenchyma. • Findings A developmental and structural pattern that we term expansigeny, as manifested by honeycomb aerenchyma, is characteristic of all aquatic basal angiosperms (the Nymphaeales) and basal monocots (the Acorales). Expansigenous aerenchyma develops by expansion of intercellular spaces into lacunae by cell division and cell expansion. Schizogeny and lysigeny, so often characterized in recent reviews as the only patterns of root cortex lacunar formation, are present in most wetland plants, but are clearly not present in the most basal flowering plants. • Conclusion We conclude that expansigeny is the basic type of aerenchyma development in roots of flowering plants and that the presence of expansigenous honeycomb aerenchyma in root cortices was fundamental to the success of the earliest flowering plants found in wetland environments. PMID:16081497

  18. A novel tracking tool for the analysis of plant-root tip movements.

    PubMed

    Russino, A; Ascrizzi, A; Popova, L; Tonazzini, A; Mancuso, S; Mazzolai, B

    2013-06-01

    The growth process of roots consists of many activities, such as exploring the soil volume, mining minerals, avoiding obstacles and taking up water to fulfil the plant's primary functions, that are performed differently, depending on environmental conditions. Root movements are strictly related to a root decision strategy, which helps plants to survive under stressful conditions by optimizing energy consumption. In this work, we present a novel image-analysis tool to study the kinematics of the root tip (apex), named analyser for root tip tracks (ARTT). The software implementation combines a segmentation algorithm with additional software imaging filters in order to realize a 2D tip detection. The resulting paths, or tracks, arise from the sampled tip positions through the acquired images during the growth. ARTT allows work with no markers and deals autonomously with new emerging root tips, as well as handling a massive number of data relying on minimum user interaction. Consequently, ARTT can be used for a wide range of applications and for the study of kinematics in different plant species. In particular, the study of the root growth and behaviour could lead to the definition of novel principles for the penetration and/or control paradigms for soil exploration and monitoring tasks. The software capabilities were demonstrated by experimental trials performed with Zea mays and Oryza sativa. PMID:23648942

  19. Conserved regulatory mechanism controls the development of cells with rooting functions in land plants

    PubMed Central

    Tam, Thomas Ho Yuen; Catarino, Bruno; Dolan, Liam

    2015-01-01

    Land plants develop filamentous cells—root hairs, rhizoids, and caulonemata—at the interface with the soil. Members of the group XI basic helix–loop–helix (bHLH) transcription factors encoded by LOTUS JAPONICUS ROOTHAIRLESS1-LIKE (LRL) genes positively regulate the development of root hairs in the angiosperms Lotus japonicus, Arabidopsis thaliana, and rice (Oryza sativa). Here we show that auxin promotes rhizoid and caulonema development by positively regulating the expression of PpLRL1 and PpLRL2, the two LRL genes in the Physcomitrella patens genome. Although the group VIII bHLH proteins, AtROOT HAIR DEFECTIVE6 and AtROOT HAIR DEFECTIVE SIX-LIKE1, promote root-hair development by positively regulating the expression of AtLRL3 in A. thaliana, LRL genes promote rhizoid development independently of PpROOT HAIR DEFECTIVE SIX-LIKE1 and PpROOT HAIR DEFECITVE SIX-LIKE2 (PpRSL1 and PpRSL2) gene function in P. patens. Together, these data demonstrate that both LRL and RSL genes are components of an ancient auxin-regulated gene network that controls the development of tip-growing cells with rooting functions among most extant land plants. Although this network has diverged in the moss and the angiosperm lineages, our data demonstrate that the core network acted in the last common ancestor of the mosses and angiosperms that existed sometime before 420 million years ago. PMID:26150509

  20. Conserved regulatory mechanism controls the development of cells with rooting functions in land plants.

    PubMed

    Tam, Thomas Ho Yuen; Catarino, Bruno; Dolan, Liam

    2015-07-21

    Land plants develop filamentous cells-root hairs, rhizoids, and caulonemata-at the interface with the soil. Members of the group XI basic helix-loop-helix (bHLH) transcription factors encoded by LOTUS JAPONICUS ROOTHAIRLESS1-LIKE (LRL) genes positively regulate the development of root hairs in the angiosperms Lotus japonicus, Arabidopsis thaliana, and rice (Oryza sativa). Here we show that auxin promotes rhizoid and caulonema development by positively regulating the expression of PpLRL1 and PpLRL2, the two LRL genes in the Physcomitrella patens genome. Although the group VIII bHLH proteins, AtROOT HAIR DEFECTIVE6 and AtROOT HAIR DEFECTIVE SIX-LIKE1, promote root-hair development by positively regulating the expression of AtLRL3 in A. thaliana, LRL genes promote rhizoid development independently of PpROOT HAIR DEFECTIVE SIX-LIKE1 and PpROOT HAIR DEFECITVE SIX-LIKE2 (PpRSL1 and PpRSL2) gene function in P. patens. Together, these data demonstrate that both LRL and RSL genes are components of an ancient auxin-regulated gene network that controls the development of tip-growing cells with rooting functions among most extant land plants. Although this network has diverged in the moss and the angiosperm lineages, our data demonstrate that the core network acted in the last common ancestor of the mosses and angiosperms that existed sometime before 420 million years ago. PMID:26150509

  1. Effects of Mycorrhizal Fungi on Rooting of Stem Cuttings and In Vitro Shoots of Woody Plants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Plants with roots colonized by mycorrhizal fungi are potentially more effective at nutrient and water acquisition, less susceptible to disease, and can be more productive under certain stressful environmental growing conditions than plants without mycorrhizae. Although a great deal of research has b...

  2. Herbivore-induced plant volatiles mediate host selection by a root herbivore.

    PubMed

    Robert, Christelle A M; Erb, Matthias; Duployer, Marianne; Zwahlen, Claudia; Doyen, Gwladys R; Turlings, Ted C J

    2012-06-01

    In response to herbivore attack, plants mobilize chemical defenses and release distinct bouquets of volatiles. Aboveground herbivores are known to use changes in leaf volatile patterns to make foraging decisions, but it remains unclear whether belowground herbivores also use volatiles to select suitable host plants. We therefore investigated how above- and belowground infestation affects the performance of the root feeder Diabrotica virgifera virgifera, and whether the larvae of this specialized beetle are able to use volatile cues to assess from a distance whether a potential host plant is already under herbivore attack. Diabrotica virgifera larvae showed stronger growth on roots previously attacked by conspecific larvae, but performed more poorly on roots of plants whose leaves had been attacked by larvae of the moth Spodoptera littoralis. Fittingly, D. virgifera larvae were attracted to plants that were infested with conspecifics, whereas they avoided plants that were attacked by S. littoralis. We identified (E)-β-caryophyllene, which is induced by D. virgifera, and ethylene, which is suppressed by S. littoralis, as two signals used by D. virgifera larvae to locate plants that are most suitable for their development. Our study demonstrates that soil-dwelling insects can use herbivore-induced changes in root volatile emissions to identify suitable host plants. PMID:22486361

  3. Influence of pumice and plant roots on substrate physical properties over time

    Technology Transfer Automated Retrieval System (TEKTRAN)

    An experiment was conducted to test the hypothesis that either pumice or plant roots maintain air space and porosity over time, or renders substrates more resistant to shrinkage. Treatment design was a 3×2 factorial with three substrate types and either presence or absence of a plant. The three su...

  4. Biostimulation of PCB-degrading bacteria by compounds released from plant roots

    SciTech Connect

    Fletcher, J.S.; Hegde, R.S.; Donnelly, P.K.

    1995-12-31

    Flavonoid and coumarin compounds produced by plants supported the growth of polychlorinated biphenyl (PCB)-degrading bacteria, and the bacteria retained their PCB-degrading properties. Root leachates and washings from mulberry trees also supported the growth of a PCB-degrading bacterium. These results indicate that chemicals released by some plant roots may serve as cometabolites for PCB-degrading bacteria. Identification of the right plant species and development of appropriate cultivation practices promises to lead to an ecologically sound means to achieve sustained in situ degradation of PCBs at contaminated terrestrial sites.

  5. Plant Nitrogen Acquisition Under Low Availability: Regulation of Uptake and Root Architecture.

    PubMed

    Kiba, Takatoshi; Krapp, Anne

    2016-04-01

    Nitrogen availability is a major factor determining plant growth and productivity. Plants acquire nitrogen nutrients from the soil through their roots mostly in the form of ammonium and nitrate. Since these nutrients are scarce in natural soils, plants have evolved adaptive responses to cope with the environment. One of the most important responses is the regulation of nitrogen acquisition efficiency. This review provides an update on the molecular determinants of two major drivers of the nitrogen acquisition efficiency: (i) uptake activity (e.g. high-affinity nitrogen transporters) and (ii) root architecture (e.g. low-nitrogen-availability-specific regulators of primary and lateral root growth). Major emphasis is laid on the regulation of these determinants by nitrogen supply at the transcriptional and post-transcriptional levels, which enables plants to optimize nitrogen acquisition efficiency under low nitrogen availability. PMID:27025887

  6. Plant Nitrogen Acquisition Under Low Availability: Regulation of Uptake and Root Architecture

    PubMed Central

    Kiba, Takatoshi; Krapp, Anne

    2016-01-01

    Nitrogen availability is a major factor determining plant growth and productivity. Plants acquire nitrogen nutrients from the soil through their roots mostly in the form of ammonium and nitrate. Since these nutrients are scarce in natural soils, plants have evolved adaptive responses to cope with the environment. One of the most important responses is the regulation of nitrogen acquisition efficiency. This review provides an update on the molecular determinants of two major drivers of the nitrogen acquisition efficiency: (i) uptake activity (e.g. high-affinity nitrogen transporters) and (ii) root architecture (e.g. low-nitrogen-availability-specific regulators of primary and lateral root growth). Major emphasis is laid on the regulation of these determinants by nitrogen supply at the transcriptional and post-transcriptional levels, which enables plants to optimize nitrogen acquisition efficiency under low nitrogen availability. PMID:27025887

  7. Phenylpropanoid pathway is potentiated by silicon in the roots of banana plants during the infection process of Fusarium oxysporum f. sp. cubense.

    PubMed

    Fortunato, Alessandro Antônio; da Silva, Washington Luís; Rodrigues, Fabrício Ávila

    2014-06-01

    Fusarium wilt, caused by Fusarium oxysporum f. sp. cubense, is a disease that causes large reductions in banana yield worldwide. Considering the importance of silicon (Si) to potentiate the resistance of several plant species to pathogen infection, this study aimed to investigate, at the histochemical level, whether this element could enhance the production of phenolics on the roots of banana plants in response to F. oxysporum f. sp. cubense infection. Plants of cultivar Maçã, which is susceptible to F. oxysporum f. sp. cubense, were grown in plastic pots amended with 0 (-Si) or 0.39 g of Si (+Si) per kilogram of soil and inoculated with race 1 of F. oxysporum f. sp. cubense. The root Si concentration was increased by 35.6% for +Si plants in comparison to the -Si plants, which contributed to a 27% reduction in the symptoms of Fusarium wilt on roots. There was an absence of fluorescence for the root sections of the -Si plants treated with the Neu and Wilson's reagents. By contrast, for the root sections obtained from the +Si plants treated with Neu's reagent, strong yellow-orange fluorescence was observed in the phloem, and lemon-yellow fluorescence was observed in the sclerenchyma and metaxylem vessels, indicating the presence of flavonoids. For the root sections of the +Si plants treated with Wilson's reagent, orange-yellowish autofluorescence was more pronounced around the phloem vessels, and yellow fluorescence was more pronounced around the metaxylem vessels, also indicating the presence of flavonoids. Lignin was more densely deposited in the cortex of the roots of the +Si plants than for the -Si plants. Dopamine was barely detected in the roots of the -Si plants after using the lactic and glyoxylic acid stain, but was strongly suspected to occur on the phloem and metaxylem vessels of the roots of the +Si plants as confirmed by the intense orange-yellow fluorescence. The present study provides new evidence of the pivotal role of the phenylpropanoid pathway in

  8. Plant Roots: The Hidden Half. Chapter 16; Calcium and Gravitropism; Revised

    NASA Technical Reports Server (NTRS)

    Poovaiah, B. W.; Reedy, A. S. N.

    1995-01-01

    Environmental signals such as light and gravity control many aspects of plant growth and development. In higher plants, the directional growth of an organ in response to stimuli such as gravity and light is considered a tropic movement. Such movement could be either positive or negative with respect to a specific stimulus. In general, stems show a positive response to light and negative response to gravity. In contrast, most roots show a positive response to gravity and a negative response to light. Investigations on plant tropism date back a century when Darwin studied the phototropic responses of maize seedlings (Darwin). Although the precise mechanism of signal perception and transduction in roots is not understood, Darwin recognized over 100 years ago that the root cap is the probable site of signal perception. He discovered that the removal of the root cap eliminates the ability of roots to respond to gravity. Other investigators have since confirmed Darwin's observation (Konings; Evans et al.). In recent years, especially with the advent of the U.S. Space Program, there has been a renewed interest in understanding how plants respond to extracellular signals such as gravity (Halstead and Dutcher). Studies on the mechanisms involved in perception and transduction of gravity signal by roots would ultimately help us to better understand gravitropism and also to grow plants under microgravity conditions as in space. In this chapter, we restrict ourselves to the role of calcium in transduction of the gravity signal. In doing so, emphasis is given to the role of calcium-modulated proteins and their role in signal transduction in gravitropism. Detailed reviews on various other aspects of gravitropism (Scott, Torrey, Wilkins, Fim and Digby, Feldman, Pickard, Moore and Evans, Halstead and Dutcher, Poovaiah et al.) and on the role of calcium as a messenger in signal transduction in general have been published (Helper and Wayne, Poovaiah and Reddy, Roberts and Hartnon

  9. Do root hydraulic properties change during the early vegetative stage of plant development in barley (Hordeum vulgare)?

    PubMed Central

    Suku, Shimi; Knipfer, Thorsten; Fricke, Wieland

    2014-01-01

    Background and Aims As annual crops develop, transpirational water loss increases substantially. This increase has to be matched by an increase in water uptake through the root system. The aim of this study was to assess the contributions of changes in intrinsic root hydraulic conductivity (Lp, water uptake per unit root surface area, driving force and time), driving force and root surface area to developmental increases in root water uptake. Methods Hydroponically grown barley plants were analysed during four windows of their vegetative stage of development, when they were 9–13, 14–18, 19–23 and 24–28 d old. Hydraulic conductivity was determined for individual roots (Lp) and for entire root systems (Lpr). Osmotic Lp of individual seminal and adventitious roots and osmotic Lpr of the root system were determined in exudation experiments. Hydrostatic Lp of individual roots was determined by root pressure probe analyses, and hydrostatic Lpr of the root system was derived from analyses of transpiring plants. Key Results Although osmotic and hydrostatic Lp and Lpr values increased initially during development and were correlated positively with plant transpiration rate, their overall developmental increases (about 2-fold) were small compared with increases in transpirational water loss and root surface area (about 10- to 40-fold). The water potential gradient driving water uptake in transpiring plants more than doubled during development, and potentially contributed to the increases in plant water flow. Osmotic Lpr of entire root systems and hydrostatic Lpr of transpiring plants were similar, suggesting that the main radial transport path in roots was the cell-to-cell path at all developmental stages. Conclusions Increase in the surface area of root system, and not changes in intrinsic root hydraulic properties, is the main means through which barley plants grown hydroponically sustain an increase in transpirational water loss during their vegetative

  10. Rooting Theories of Plant Community Ecology in Microbial Interactions

    PubMed Central

    Bever, James D.; Dickie, Ian A.; Facelli, Evelina; Facelli, Jose M.; Klironomos, John; Moora, Mari; Rillig, Matthias C.; Stock, William D.; Tibbett, Mark; Zobel, Martin

    2010-01-01

    Predominant frameworks for understanding plant ecology have an aboveground bias that neglects soil micro-organisms. This is inconsistent with recent work illustrating the importance of soil microbes in terrestrial ecology. Microbial effects have been incorporated into plant community dynamics using ideas of niche modification and plant-soil community feedbacks. Here, we expand and integrate qualitative conceptual models of plant niche and feedback to explore implications of microbial interactions for understanding plant community ecology. At the same time we review the empirical evidence for these processes. We also consider common mycorrhizal networks, and suggest these are best interpreted within the feedback framework. Finally, we apply our integrated model of niche and feedback to understanding plant coexistence, monodominance, and invasion ecology. PMID:20557974

  11. Understanding the development of roots exposed to contaminants and the potential of plant-associated bacteria for optimization of growth

    PubMed Central

    Remans, Tony; Thijs, Sofie; Truyens, Sascha; Weyens, Nele; Schellingen, Kerim; Keunen, Els; Gielen, Heidi; Cuypers, Ann; Vangronsveld, Jaco

    2012-01-01

    Background and Scope Plant responses to the toxic effects of soil contaminants, such as excess metals or organic substances, have been studied mainly at physiological, biochemical and molecular levels, but the influence on root system architecture has received little attention. Nevertheless, the precise position, morphology and extent of roots can influence contaminant uptake. Here, data are discussed that aim to increase the molecular and ecological understanding of the influence of contaminants on root system architecture. Furthermore, the potential of plant-associated bacteria to influence root growth by their growth-promoting and stress-relieving capacities is explored. Methods Root growth parameters of Arabidopsis thaliana seedlings grown in vertical agar plates are quantified. Mutants are used in a reverse genetics approach to identify molecular components underlying quantitative changes in root architecture after exposure to excess cadmium, copper or zinc. Plant-associated bacteria are isolated from contaminated environments, genotypically and phenotypically characterized, and used to test plant root growth improvement in the presence of contaminants. Key Results The molecular determinants of primary root growth inhibition and effects on lateral root density by cadmium were identified. A vertical split-root system revealed local effects of cadmium and copper on root development. However, systemic effects of zinc exposure on root growth reduced both the avoidance of contaminated areas and colonization of non-contaminated areas. The potential for growth promotion and contaminant degradation of plant-associated bacteria was demonstrated by improved root growth of inoculated plants exposed to 2,4-di-nitro-toluene (DNT) or cadmium. Conclusions Knowledge concerning the specific influence of different contaminants on root system architecture and the molecular mechanisms by which this is achieved can be combined with the exploitation of plant-associated bacteria to

  12. Integrating roots into a whole plant network of flowering time genes in Arabidopsis thaliana.

    PubMed

    Bouché, Frédéric; D'Aloia, Maria; Tocquin, Pierre; Lobet, Guillaume; Detry, Nathalie; Périlleux, Claire

    2016-01-01

    Molecular data concerning the involvement of roots in the genetic pathways regulating floral transition are lacking. In this study, we performed global analyses of the root transcriptome in Arabidopsis in order to identify flowering time genes that are expressed in the roots and genes that are differentially expressed in the roots during the induction of flowering. Data mining of public microarray experiments uncovered that about 200 genes whose mutations are reported to alter flowering time are expressed in the roots (i.e. were detected in more than 50% of the microarrays). However, only a few flowering integrator genes passed the analysis cutoff. Comparison of root transcriptome in short days and during synchronized induction of flowering by a single 22-h long day revealed that 595 genes were differentially expressed. Enrichment analyses of differentially expressed genes in root tissues, gene ontology categories, and cis-regulatory elements converged towards sugar signaling. We concluded that roots are integrated in systemic signaling, whereby carbon supply coordinates growth at the whole plant level during the induction of flowering. This coordination could involve the root circadian clock and cytokinin biosynthesis as a feed forward loop towards the shoot. PMID:27352932

  13. Integrating roots into a whole plant network of flowering time genes in Arabidopsis thaliana

    PubMed Central

    Bouché, Frédéric; D’Aloia, Maria; Tocquin, Pierre; Lobet, Guillaume; Detry, Nathalie; Périlleux, Claire

    2016-01-01

    Molecular data concerning the involvement of roots in the genetic pathways regulating floral transition are lacking. In this study, we performed global analyses of the root transcriptome in Arabidopsis in order to identify flowering time genes that are expressed in the roots and genes that are differentially expressed in the roots during the induction of flowering. Data mining of public microarray experiments uncovered that about 200 genes whose mutations are reported to alter flowering time are expressed in the roots (i.e. were detected in more than 50% of the microarrays). However, only a few flowering integrator genes passed the analysis cutoff. Comparison of root transcriptome in short days and during synchronized induction of flowering by a single 22-h long day revealed that 595 genes were differentially expressed. Enrichment analyses of differentially expressed genes in root tissues, gene ontology categories, and cis-regulatory elements converged towards sugar signaling. We concluded that roots are integrated in systemic signaling, whereby carbon supply coordinates growth at the whole plant level during the induction of flowering. This coordination could involve the root circadian clock and cytokinin biosynthesis as a feed forward loop towards the shoot. PMID:27352932

  14. Ecophysiology of wetland plant roots: A modelling comparison of aeration in relation to species distribution

    USGS Publications Warehouse

    Sorrell, B.K.; Mendelssohn, I.A.; McKee, K.L.; Woods, R.A.

    2000-01-01

    This study examined the potential for inter-specific differences in root aeration to determine wetland plant distribution in nature. We compared aeration in species that differ in the type of sediment and depth of water they colonize. Differences in root anatomy, structure and physiology were applied to aeration models that predicted the maximum possible aerobic lengths and development of anoxic zones in primary adventitious roots. Differences in anatomy and metabolism that provided higher axial fluxes of oxygen allowed deeper root growth in species that favour more reducing sediments and deeper water. Modelling identified factors that affected growth in anoxic soils through their effects on aeration. These included lateral root formation, which occurred at the expense of extension of the primary root because of the additional respiratory demand they imposed, reducing oxygen fluxes to the tip and stele, and the development of stelar anoxia. However, changes in sediment oxygen demand had little detectable effect on aeration in the primary roots due to their low wall permeability and high surface impedance, but appeared to reduce internal oxygen availability by accelerating loss from laterals. The development of pressurized convective gas flow in shoots and rhizomes was also found to be important in assisting root aeration, as it maintained higher basal oxygen concentrations at the rhizome-root junctions in species growing into deep water. (C) 2000 Annals of Botany Company.

  15. Klebsiella pneumoniae inoculants for enhancing plant growth

    DOEpatents

    Triplett, Eric W.; Kaeppler, Shawn M.; Chelius, Marisa K.

    2008-07-01

    A biological inoculant for enhancing the growth of plants is disclosed. The inoculant includes the bacterial strains Herbaspirillum seropedicae 2A, Pantoea agglomerans P101, Pantoea agglomerans P102, Klebsiella pneumoniae 342, Klebsiella pneumoniae zmvsy, Herbaspirillum seropedicae Z152, Gluconacetobacter diazotrophicus PA15, with or without a carrier. The inoculant also includes strains of the bacterium Pantoea agglomerans and K. pneumoniae which are able to enhance the growth of cereal grasses. Also disclosed are the novel bacterial strains Herbaspirillum seropedicae 2A, Pantoea agglomerans P101 and P102, and Klebsiella pneumoniae 342 and zmvsy.

  16. Dynamic aspects of soil water availability for isohydric plants: Focus on root hydraulic resistances

    NASA Astrophysics Data System (ADS)

    Couvreur, V.; Vanderborght, J.; Draye, X.; Javaux, M.

    2014-11-01

    Soil water availability for plant transpiration is a key concept in agronomy. The objective of this study is to revisit this concept and discuss how it may be affected by processes locally influencing root hydraulic properties. A physical limitation to soil water availability in terms of maximal flow rate available to plant leaves (Qavail) is defined. It is expressed for isohydric plants, in terms of plant-centered variables and properties (the equivalent soil water potential sensed by the plant, ψs eq; the root system equivalent conductance, Krs; and a threshold leaf water potential, ψleaf lim). The resulting limitation to plant transpiration is compared to commonly used empirical stress functions. Similarities suggest that the slope of empirical functions might correspond to the ratio of Krs to the plant potential transpiration rate. The sensitivity of Qavail to local changes of root hydraulic conductances in response to soil matric potential is investigated using model simulations. A decrease of radial conductances when the soil dries induces earlier water stress, but allows maintaining higher night plant water potentials and higher Qavail during the last week of a simulated 1 month drought. In opposition, an increase of radial conductances during soil drying provokes an increase of hydraulic redistribution and Qavail at short term. This study offers a first insight on the effect of dynamic local root hydraulic properties on soil water availability. By better understanding complex interactions between hydraulic processes involved in soil-plant hydrodynamics, better prospects on how root hydraulic traits mitigate plant water stress might be achieved.

  17. Effect of plant-uptake representation on the water-optimal root depth

    NASA Astrophysics Data System (ADS)

    Guswa, A. J.

    2008-12-01

    The depth of roots depends on a variety of conditions, including soil properties, plant type, nutrient availability, and climate. A focus on water enables the determination of a water-optimal root depth by equating the marginal carbon cost of deeper roots with the benefit of those roots to continued transpiration and carbon assimilation. Calculation of the transpiration benefit requires the mathematical representation of plant uptake as a function of root depth and soil moisture. This work compares the effect of two bounding representations of plant uptake on the water-optimal root depth and the response of that depth to changes in precipitation. Soil-moisture dynamics are driven by precipitation events that arrive as a Poisson process and are characterized by a mean frequency and depth. Infiltration and drainage are instantaneous, filling the root zone up to a maximum field capacity. Plant uptake is represented in one case as a step function of soil moisture; transpiration proceeds at a potential rate until the wilting-point saturation is reached when uptake drops to zero. Until that critical threshold, soil moisture has no effect on transpiration. In the second case, transpiration decreases linearly from its potential at field capacity to zero at the wilting point; soil moisture exerts a continuous and gradual influence on plant uptake throughout the drying cycle. With both the linear and step-function representations, the water-optimal root depth is more sensitive to changes in precipitation depth than frequency under dry conditions and more sensitive to precipitation frequency when the climate is wet. Under wet conditions, optimal root depths predicted with the step function show a greater sensitivity to climate than do those based on the linear model. Under dry conditions, the reverse is true; the water-optimal root depth is slightly more sensitive to changes in precipitation when the linear model is employed than when the step function is used. For all

  18. Plant diversity and root traits benefit physical properties key to soil function in grasslands.

    PubMed

    Gould, Iain J; Quinton, John N; Weigelt, Alexandra; De Deyn, Gerlinde B; Bardgett, Richard D

    2016-09-01

    Plant diversity loss impairs ecosystem functioning, including important effects on soil. Most studies that have explored plant diversity effects belowground, however, have largely focused on biological processes. As such, our understanding of how plant diversity impacts the soil physical environment remains limited, despite the fundamental role soil physical structure plays in ensuring soil function and ecosystem service provision. Here, in both a glasshouse and a long-term field study, we show that high plant diversity in grassland systems increases soil aggregate stability, a vital structural property of soil, and that root traits play a major role in determining diversity effects. We also reveal that the presence of particular plant species within mixed communities affects an even wider range of soil physical processes, including hydrology and soil strength regimes. Our results indicate that alongside well-documented effects on ecosystem functioning, plant diversity and root traits also benefit essential soil physical properties. PMID:27459206

  19. Enhanced Growth of Wheat and Soybean Plants Inoculated with Azospirillum brasilense Is Not Necessarily Due to General Enhancement of Mineral Uptake †

    PubMed Central

    Bashan, Yoav; Harrison, S. Kent; Whitmoyer, Robert E.

    1990-01-01

    The capacity of Azospirillum brasilense to enhance the accumulation of K+, P, Ca2+, Mg2+, S, Na+, Mn2+, Fe2+, B, Cu2+, and Zn2+ in inoculated wheat and soybean plants was evaluated by using two different analytical methods with five A. brasilense strains originating from four distinct geographical regions. A Pseudomonas isolate from the rhizosphere of Zea mays seedlings was included as a control. All A. brasilense strains significantly improved wheat and soybean growth by increasing root and shoot dry weight and root surface area. The degree of plant response to inoculation varied among the different strains of A. brasilense. All strains were capable of colonizing roots, but the best root colonizer, Pseudomonas sp., had no effect on plant growth. The numbers of organisms of Brazilian strains Sp-245 and Sp-246 colonizing roots were similar regardless of the host plant. Numbers of organisms for the other strains were directly dependent on the host plant. The main feature characterizing mineral accumulation in inoculated plants was that all inoculation treatments changed the mineral balance of the plants, but in an inconsistent manner. Enhancement of mineral uptake by plants also varied among strains to a great extent and was directly dependent on the strain-plant combination; i.e., a strain capable of increasing accumulation of a particular ion in one plant species or cultivar often lacked the ability to do so in another. Minerals in inoculated plants were not evenly distributed in different plant tissues, and the changes varied among groups of plants within each bacterial strain inoculation treatment. We suggest that, although A. brasilense strains are capable of changing the mineral balance and content of plants, it is unlikely that this ability is a general mechanism responsible for plant improvement by A. brasilense. Images PMID:16348150

  20. Characterization of cadmium-resistant bacteria for its potential in promoting plant growth and cadmium accumulation in Sesbania bispinosa root.

    PubMed

    Kartik, V P; Jinal, H N; Amaresan, N

    2016-11-01

    The cadmium (Cd) resistant bacteria were isolated from soils of Damanganga river, Vapi, and identified 11 potential Cd resistant bacteria based on 16S rDNA sequences. The Cd resistant bacteria belonged to four different genera: Providencia spp., Morganella sp., Stenotrophomonas sp., and Bacillus spp. The assessment of plant growth-promoting (PGP) parameters revealed that the Cd tolerant bacteria showed one or more PGP properties. Further, a pot experiment was conducted to elucidate the effects of Cd resistant bacteria on the plant growth and the uptake of Cd by Sesbania bispinosa. The bacterized seedlings recorded 36.0-74.8% and 21.2-32.9% higher root and shoot lengths, respectively, in Cd amended soil compared with control. The Cd mobilization in the root of S. bispinosa by microbial inoculants ranged from 0.02 ± 0.01 to 1.11 ± 0.06 ppm. The enhanced concentrations of Cd accumulation in S. bispinosa roots correspond to the effect of the bacterial strains on metal mobilization in soil. The present observations showed that the Cd resistant strains protect the plants against the inhibitory effects of Cd, probably due to the production of PGP properties. The present results provided a new insight into the phytoremediation of Cd contaminated soil. PMID:27185302

  1. Impact of elemental uptake in the root chemistry of wetland plants.

    PubMed

    Aryal, Rupak; Nirola, Ramkrishna; Beecham, Simon; Kamruzzaman, Mohammad

    2016-09-01

    Plants play a key role in the accumulation of metals in contaminated environment. Ephemeral plants, such as cyperus vaginatus, from the family Cyperaceae have been used in constructed wetlands to alter the biogeochemistry of waterlogged soils. High elemental content in wetlands often induces chemical changes in the root, stem and leaf of wetland plants. Elemental uptake and possible chemical changes in the roots of Cyperus vaginatus was investigated and compared with plants grown away from the wetland. Among the 9 heavy metals (Cr, Mn, Fe, Co, Ni, Cu, Zn, Cd, and Pb) and metalloid (As) measured, with the exception of Mn, all metals had higher content in the plant roots grown within the wetland. This was followed by plants grown near to the wetland that receive stormwater occasionally and then plants grown far from the wetland. The 3-D fluorescence spectra record showed notable differences in the chemical composition of roots grown in the three locations. The spectra combined with parallel factor analysis showed three dominant fluorescence components. Comparison of the fluorescence signatures showed a continuum of spectral properties constrained by the degree of metal contamination. PMID:26709636

  2. Mathematical modelling study for water uptake of steadily growing plant root

    NASA Astrophysics Data System (ADS)

    Chu, Jiaqing; Jiao, Weiping; Xu, Jianjun

    2008-02-01

    The root system of plant is a vitally important organ for living plant. One of the major functions of the root system is uptaking water and nutrients from the soil. The present paper analyzes the whole process of water uptake from soil by a steadily growing plant with a single slender root. We start from the basic principles of physics and fluid-dynamics, consider the structure characteristics of the water transport channel formed by the tiny xylems tubes inside plant, and establish a simplified coherent mathematical model to describe the water transport in the complete system consisting of soil, individual plant, including root, stem and leaves-atmosphere, on the basis of the plant physiology. Moreover, we resolve the proposed mathematical model for a simple artificial plant model under a variety of conditions, in terms of the numerical approach as well as analytical approach. It is shown that the results obtained by both approaches are in very good agreement; the theoretical predictions are qualitatively consistent with the practical experiences very well. The simplified mathematical model established in the present paper may provide a basis for the further investigations on the more sophisticated mathematical model.

  3. Swarms, swarming and entanglements of fungal hyphae and of plant roots

    PubMed Central

    Barlow, Peter W.; Fisahn, Joachim

    2013-01-01

    There has been recent interest in the possibility that plant roots can show oriented collective motion, or swarming behavior. We examine the evidence supportive of root swarming and we also present new observations on this topic. Seven criteria are proposed for the definition of a swarm, whose application can help identify putative swarming behavior in plants. Examples where these criteria are fulfilled, at many levels of organization, are presented in relation to plant roots and root systems, as well as to the root-like mycelial cords (rhizomorphs) of fungi. The ideas of both an “active” swarming, directed by a signal which imposes a common vector on swarm element aggregation, and a “passive” swarming, where aggregation results from external constraint, are introduced. Active swarming is a pattern of cooperative behavior peculiar to the sporophyte generation of vascular plants and is the antithesis of the competitive behavior shown by the gametophyte generation of such plants, where passive swarming may be found. Fungal mycelial cords could serve as a model example of swarming in a multi-cellular, non-animal system. PMID:24255743

  4. Coke dust enhances coke plant wastewater treatment.

    PubMed

    Burmistrz, Piotr; Rozwadowski, Andrzej; Burmistrz, Michał; Karcz, Aleksander

    2014-12-01

    Coke plant wastewater contain many toxic pollutants. Despite physico-chemical and biological treatment this specific type of wastewater has a significant impact on environment and human health. This article presents results of research on industrial adsorptive coke plant wastewater treatment. As a sorbent the coke dust, dozen times less expensive than pulverized activated carbon, was used. Treatment was conducted in three scenarios: adsorptive after full treatment with coke dust at 15 g L(-1), biological treatment enhanced with coke dust at 0.3-0.5 g L(-1) and addition of coke dust at 0.3 g L(-1) prior to the biological treatment. The enhanced biological treatment proved the most effective. It allowed additional removal of 147-178 mg COD kg(-1) of coke dust. PMID:25113994

  5. Germination and root elongation bioassays in six different plant species for testing Ni contamination in soil.

    PubMed

    Visioli, Giovanna; Conti, Federica D; Gardi, Ciro; Menta, Cristina

    2014-04-01

    In vitro short-term chronic phytotoxicity germination and root elongation test were applied to test the effects of nickel (Ni) in seed germination and root elongation in six plants species: Cucumis sativus (Cucurbitaceae), Lepidium sativum and Brassica nigra (Brassicaceae), Trifolium alexandrinum and Medicago sativa (Fabaceae), Phacelia tanacetifolia (Boraginaceae). A naturally Ni rich soil was used to compare the results obtained. Unlike root elongation, germination was not affected by Ni in any of the six species tested. EC50 values, calculated on the root elongation, showed that Ni toxicity decreases in the following order: P. tanacetifolia > B. nigra > C. sativus > L. sativum > M. sativa > T. alexandrinum. The test conducted using soil elutriate revealed a significantly lower effect in both seed germination and root elongation when compared to the results obtained using untreated soil. Conversely, the test performed on soil confirmed the high sensitivity of C. sativus, P. tanacetifolia and L. sativum to Ni. PMID:24288040

  6. Arbuscular mycorrhizal fungal hyphae contribute to the uptake of polycyclic aromatic hydrocarbons by plant roots.

    PubMed

    Gao, Yanzheng; Cheng, Zhaoxia; Ling, Wanting; Huang, Jing

    2010-09-01

    The arbuscular mycorrhizal (AM) hyphae-mediated uptake of polycyclic aromatic hydrocarbons (PAHs) by the roots of ryegrass (Lolium multiflorum Lam.) was investigated using three-compartment systems. Glomus mosseae and Glomus etunicatum were chosen, and fluorene and phenanthrene were used as representative PAHs. When roots were grown in un-spiked soils, AM hyphae extended into PAH-spiked soil and clearly absorbed and transported PAHs to roots, resulting in high concentrations of fluorene and phenanthrene in roots. This was further confirmed by the batch equilibration experiment, which revealed that the partition coefficients (K(d)) of tested PAHs by mycorrhizal hyphae were 270-356% greater than those by roots, suggesting the great potential of hyphae to absorb PAHs. Because of fluorene's lower molecular weight and higher water solubility, its translocation by hyphae was greater than that of phenanthrene. These results provide new perspectives on the AM hyphae-mediated uptake by plants of organic contaminants from soil. PMID:20403686

  7. Enhancement of root hydraulic conductivity by methyl jasmonate and the role of calcium and abscisic acid in this process.

    PubMed

    Sánchez-Romera, Beatriz; Ruiz-Lozano, Juan Manuel; Li, Guowei; Luu, Doan-Trung; Martínez-Ballesta, Maria del Carmen; Carvajal, Micaela; Zamarreño, Angel María; García-Mina, Jose María; Maurel, Christophe; Aroca, Ricardo

    2014-04-01

    The role of jasmonic acid in the induction of stomatal closure is well known. However, its role in regulating root hydraulic conductivity (L) has not yet been explored. The objectives of the present research were to evaluate how JA regulates L and how calcium and abscisic acid (ABA) could be involved in such regulation. We found that exogenous methyl jasmonate (MeJA) increased L of Phaseolus vulgaris, Solanum lycopersicum and Arabidopsis thaliana roots. Tomato plants defective in JA biosynthesis had lower values of L than wild-type plants, and that L was restored by addition of MeJA. The increase of L by MeJA was accompanied by an increase of the phosphorylation state of the aquaporin PIP2. We observed that MeJA addition increased the concentration of cytosolic calcium and that calcium channel blockers inhibited the rise of L caused by MeJA. Treatment with fluoridone, an inhibitor of ABA biosynthesis, partially inhibited the increase of L caused by MeJA, and tomato plants defective in ABA biosynthesis increased their L after application of MeJA. It is concluded that JA enhances L and that this enhancement is linked to calcium and ABA dependent and independent signalling pathways. PMID:24131347

  8. Plant Invasions Associated with Change in Root-Zone Microbial Community Structure and Diversity.

    PubMed

    Rodrigues, Richard R; Pineda, Rosana P; Barney, Jacob N; Nilsen, Erik T; Barrett, John E; Williams, Mark A

    2015-01-01

    The importance of plant-microbe associations for the invasion of plant species have not been often tested under field conditions. The research sought to determine patterns of change in microbial communities associated with the establishment of invasive plants with different taxonomic and phenetic traits. Three independent locations in Virginia, USA were selected. One site was invaded by a grass (Microstegium vimineum), another by a shrub (Rhamnus davurica), and the third by a tree (Ailanthus altissima). The native vegetation from these sites was used as reference. 16S rRNA and ITS regions were sequenced to study root-zone bacterial and fungal communities, respectively, in invaded and non-invaded samples and analyzed using Quantitative Insights Into Microbial Ecology (QIIME). Though root-zone microbial community structure initially differed across locations, plant invasion shifted communities in similar ways. Indicator species analysis revealed that Operational Taxonomic Units (OTUs) closely related to Proteobacteria, Acidobacteria, Actinobacteria, and Ascomycota increased in abundance due to plant invasions. The Hyphomonadaceae family in the Rhodobacterales order and ammonia-oxidizing Nitrospirae phylum showed greater relative abundance in the invaded root-zone soils. Hyphomicrobiaceae, another bacterial family within the phyla Proteobacteria increased as a result of plant invasion, but the effect associated most strongly with root-zones of M. vimineum and R. davurica. Functional analysis using Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt) showed bacteria responsible for nitrogen cycling in soil increased in relative abundance in association with plant invasion. In agreement with phylogenetic and functional analyses, greater turnover of ammonium and nitrate was associated with plant invasion. Overall, bacterial and fungal communities changed congruently across plant invaders, and support the hypothesis that nitrogen

  9. Plant Invasions Associated with Change in Root-Zone Microbial Community Structure and Diversity

    PubMed Central

    Rodrigues, Richard R.; Pineda, Rosana P.; Barney, Jacob N.; Nilsen, Erik T.; Barrett, John E.; Williams, Mark A.

    2015-01-01

    The importance of plant-microbe associations for the invasion of plant species have not been often tested under field conditions. The research sought to determine patterns of change in microbial communities associated with the establishment of invasive plants with different taxonomic and phenetic traits. Three independent locations in Virginia, USA were selected. One site was invaded by a grass (Microstegium vimineum), another by a shrub (Rhamnus davurica), and the third by a tree (Ailanthus altissima). The native vegetation from these sites was used as reference. 16S rRNA and ITS regions were sequenced to study root-zone bacterial and fungal communities, respectively, in invaded and non-invaded samples and analyzed using Quantitative Insights Into Microbial Ecology (QIIME). Though root-zone microbial community structure initially differed across locations, plant invasion shifted communities in similar ways. Indicator species analysis revealed that Operational Taxonomic Units (OTUs) closely related to Proteobacteria, Acidobacteria, Actinobacteria, and Ascomycota increased in abundance due to plant invasions. The Hyphomonadaceae family in the Rhodobacterales order and ammonia-oxidizing Nitrospirae phylum showed greater relative abundance in the invaded root-zone soils. Hyphomicrobiaceae, another bacterial family within the phyla Proteobacteria increased as a result of plant invasion, but the effect associated most strongly with root-zones of M. vimineum and R. davurica. Functional analysis using Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt) showed bacteria responsible for nitrogen cycling in soil increased in relative abundance in association with plant invasion. In agreement with phylogenetic and functional analyses, greater turnover of ammonium and nitrate was associated with plant invasion. Overall, bacterial and fungal communities changed congruently across plant invaders, and support the hypothesis that nitrogen

  10. Enhancing phosphorus and zinc acquisition efficiency in rice: a critical review of root traits and their potential utility in rice breeding

    PubMed Central

    Rose, T. J.; Impa, S. M.; Rose, M. T.; Pariasca-Tanaka, J.; Mori, A.; Heuer, S.; Johnson-Beebout, S. E.; Wissuwa, M.

    2013-01-01

    Background Rice is the world's most important cereal crop and phosphorus (P) and zinc (Zn) deficiency are major constraints to its production. Where fertilizer is applied to overcome these nutritional constraints it comes at substantial cost to farmers and the efficiency of fertilizer use is low. Breeding crops that are efficient at acquiring P and Zn from native soil reserves or fertilizer sources has been advocated as a cost-effective solution, but would benefit from knowledge of genes and mechanisms that confer enhanced uptake of these nutrients by roots. Scope This review discusses root traits that have been linked to P and Zn uptake in rice, including traits that increase mobilization of P/Zn from soils, increase the volume of soil explored by roots or root surface area to recapture solubilized nutrients, enhance the rate of P/Zn uptake across the root membrane, and whole-plant traits that affect root growth and nutrient capture. In particular, this review focuses on the potential for these traits to be exploited through breeding programmes to produce nutrient-efficient crop cultivars. Conclusions Few root traits have so far been used successfully in plant breeding for enhanced P and Zn uptake in rice or any other crop. Insufficient genotypic variation for traits or the failure to enhance nutrient uptake under realistic field conditions are likely reasons for the limited success. More emphasis is needed on field studies in mapping populations or association panels to identify those traits and underlying genes that are able to enhance nutrient acquisition beyond the level already present in most cultivars. PMID:23071218

  11. Transgenic plants that exhibit enhanced nitrogen assimilation

    SciTech Connect

    Coruzzi, G.M.; Brears, T.

    1999-09-21

    The present invention relates to a method for producing plants with improved agronomic and nutritional traits. Such traits include enhanced nitrogen assimilatory and utilization capacities, faster and more vigorous growth, greater vegetative and reproductive yields, and enriched or altered nitrogen content in vegetative and reproductive parts. More particularly, the invention relates to the engineering of plants modified to have altered expression of key enzymes in the nitrogen assimilation and utilization pathways. In one embodiment of the present invention, the desired altered expression is accomplished by engineering the plant for ectopic overexpression of one of more the native or modified nitrogen assimilatory enzymes. The invention also has a number of other embodiments, all of which are disclosed.

  12. Transgenic plants that exhibit enhanced nitrogen assimilation

    DOEpatents

    Coruzzi, Gloria M.; Brears, Timothy

    2000-01-01

    The present invention relates to a method for producing plants with improved agronomic and nutritional traits. Such traits include enhanced nitrogen assimilatory and utilization capacities, faster and more vigorous growth, greater vegetative and reproductive yields, and enriched or altered nitrogen content in vegetative and reproductive parts. More particularly, the invention relates to the engineering of plants modified to have altered expression of key enzymes in the nitrogen assimilation and utilization pathways. In one embodiment of the present invention, the desired altered expression is accomplished by engineering the plant for ectopic overexpression of one of more the native or modified nitrogen assimilatory enzymes. The invention also has a number of other embodiments, all of which are disclosed herein.

  13. Transgenic plants that exhibit enhanced nitrogen assimilation

    DOEpatents

    Coruzzi, Gloria M.; Brears, Timothy

    1999-01-01

    The present invention relates to a method for producing plants with improved agronomic and nutritional traits. Such traits include enhanced nitrogen assimilatory and utilization capacities, faster and more vigorous growth, greater vegetative and reproductive yields, and enriched or altered nitrogen content in vegetative and reproductive parts. More particularly, the invention relates to the engineering of plants modified to have altered expression of key enzymes in the nitrogen assimilation and utilization pathways. In one embodiment of the present invention, the desired altered expression is accomplished by engineering the plant for ectopic overexpression of one of more the native or modified nitrogen assimilatory enzymes. The invention also has a number of other embodiments, all of which are disclosed herein.

  14. Transgenic plants that exhibit enhanced nitrogen assimilation

    DOEpatents

    Coruzzi, Gloria M.; Brears, Timothy

    2005-03-08

    The present invention relates to a method for producing plants with improved agronomic and nutritional traits. Such traits include enhanced nitrogen assimilatory and utilization capacities, faster and more vigorous growth, greater vegetative and reproductive yields, and enriched or altered nitrogen content in vegetative and reproductive parts. More particularly, the invention relates to the engineering of plants modified to have altered expression of key enzymes in the nitrogen assimilation and utilization pathways. In one embodiment of the present invention, the desired altered expression is accomplished by engineering the plant for ectopic overexpression of one of more the native or modified nitrogen assimilatory enzymes. The invention also has a number of other embodiments, all of which are disclosed herein.

  15. Self-arrangement of cellular circadian rhythms through phase-resetting in plant roots

    NASA Astrophysics Data System (ADS)

    Fukuda, Hirokazu; Ukai, Kazuya; Oyama, Tokitaka

    2012-10-01

    We discovered a striped pattern of gene expression with circadian rhythms in growing plant roots using bioluminescent imaging of gene expression. Our experimental analysis revealed that the stripe wave in the bioluminescent image originated at the root tip and was caused by a continuous phase resetting of circadian oscillations. Some complex stripe waves containing arrhythmic regions were also observed. We succeeded in describing the formation mechanisms of these patterns using a growing phase oscillator network with a phase-resetting boundary condition.

  16. Mechanosensitivity below Ground: Touch-Sensitive Smell-Producing Roots in the Shy Plant Mimosa pudica.

    PubMed

    Musah, Rabi A; Lesiak, Ashton D; Maron, Max J; Cody, Robert B; Edwards, David; Fowble, Kristen L; Dane, A John; Long, Michael C

    2016-02-01

    The roots of the shy plant Mimosa pudica emit a cocktail of small organic and inorganic sulfur compounds and reactive intermediates into the environment, including SO2, methanesulfinic acid, pyruvic acid, lactic acid, ethanesulfinic acid, propanesulfenic acid, 2-aminothiophenol, S-propyl propane 1-thiosulfinate, phenothiazine, and thioformaldehyde, an elusive and highly unstable compound that, to our knowledge, has never before been reported to be emitted by a plant. When soil around the roots is dislodged or when seedling roots are touched, an odor is detected. The perceived odor corresponds to the emission of higher amounts of propanesulfenic acid, 2-aminothiophenol, S-propyl propane 1-thiosulfinate, and phenothiazine. The mechanosensitivity response is selective. Whereas touching the roots with soil or human skin resulted in odor detection, agitating the roots with other materials such as glass did not induce a similar response. Light and electron microscopy studies of the roots revealed the presence of microscopic sac-like root protuberances. Elemental analysis of these projections by energy-dispersive x-ray spectroscopy revealed them to contain higher levels of K(+) and Cl(-) compared with the surrounding tissue. Exposing the protuberances to stimuli that caused odor emission resulted in reductions in the levels of K(+) and Cl(-) in the touched area. The mechanistic implications of the variety of sulfur compounds observed vis-à-vis the pathways for their formation are discussed. PMID:26661932

  17. Meta-analysis of the effects of plant roots in controlling concentrated flow erosion rates

    NASA Astrophysics Data System (ADS)

    Vannoppen, Wouter; Poesen, Jean; Vanmaercke, Matthias; De Baets, Sarah

    2015-04-01

    Vegetation is often used in ecological restoration programs to control various soil erosion processes. During the last two decades several studies reported on the effects of plant roots in controlling concentrated flow erosion rates. However a global analysis of the now available data on root effects is still lacking. Yet, a meta-data analysis will contribute to a better understanding of the soil-root interactions as our capability to assess the effectiveness of roots in reducing soil erosion rates due to concentrated flow in different environments remains difficult. The objectives of this study are therefore i) to provide a state of the art on studies quantifying the effectiveness of roots in reducing soil erosion rates due to concentrated flow; and ii) to explore the overall trends in erosion reduction as a function of the root (length) density, root system architecture and soil texture, based on a global analysis of published research data. We therefore compiled a dataset of measured relative soil detachment rates (RSD) for the root density (RD; 822 observations) as well as the root length density (RLD; 274 observations). Non-linear regression analyses showed that decreases in RSD as a function of RD and RLD could be best described with the Hill curve model. However, a large proportion of the variability in RSD could not be attributed to RD or RLD, resulting in a relatively low predictive accuracy of the Hill curve model with model efficiencies of 0.11 and 0.17 for RD and RLD respectively. Considering root architecture and soil texture yielded a better predictive model especially for RLD with ME of 0.37 for fibrous roots in a non-sandy soil. The unexplained variance is to a large extent attributable to measuring errors and differences in experimental set ups that could not be explicitly accounted for (e.g. tested plant species, soil and flow characteristics). However, using a Monte Carlo simulation approach, we were able to establish relationships that allow

  18. Time-lapse ERT for the monitoring of soil-plant interactions in the root zone

    NASA Astrophysics Data System (ADS)

    Cassiani, G.; Boaga, J.; Rossi, M.; D'Alpaos, A.; Fadda, G.; Putti, M.; Marani, M.

    2013-12-01

    The application of time-lapse non invasive 3D micro-scale electrical resistivity tomography (ERT) has been proven to be an efficient tool to monitor the soil-plant interactions and particularly the root zone activity. This information can support water balance modeling in the upper subsoil critical zone. Here we present the results of two field experiments in very different environments: the case of a single apple tree in an orchard located in the Trentino region (Northern Italy), and the case of salt-marshes plants in the Venice Lagoon. The micro-scale ERT apparatus consists of buried electrodes installed on micro boreholes, plus mini-electrodes on the ground surface. We collected repeated ERT, TDR and tensiometer data. For the apple orchard site test we adopted controlled irrigation tests in different seasons, while in the lagoon salt-marshes we monitored the root-plant activity during tidal flooding. The results demonstrate that micro-scale ERT is a very effective tool to characterize subsoil conditions and monitor root zone activities, especially in terms of root zone suction regions. Micro-scale ERT can detect the main suction zones caused by the tree root activity, as demonstrated in the case of the apple orchard, while ERT and moisture measurements in the lagoon environment show a high resistivity suction layer located at root depth even during marsh flooding. Both observations will be important pieces of information for the comprehension of relevant eco- hydrological dynamics.

  19. Time-lapse ERT for the monitoring of soil-plant interactions in the root zone

    NASA Astrophysics Data System (ADS)

    Cassiani, G.; Boaga, J.; Rossi, M.; D'Alpaos, A.; Fadda, G.; Putti, M.; Marani, M.

    2011-12-01

    The application of time-lapse non invasive 3D micro-scale electrical resistivity tomography (ERT) has been proven to be an efficient tool to monitor the soil-plant interactions and particularly the root zone activity. This information can support water balance modeling in the upper subsoil critical zone. Here we present the results of two field experiments in very different environments: the case of a single apple tree in an orchard located in the Trentino region (Northern Italy), and the case of salt-marshes plants in the Venice Lagoon. The micro-scale ERT apparatus consists of buried electrodes installed on micro boreholes, plus mini-electrodes on the ground surface. We collected repeated ERT, TDR and tensiometer data. For the apple orchard site test we adopted controlled irrigation tests in different seasons, while in the lagoon salt-marshes we monitored the root-plant activity during tidal flooding. The results demonstrate that micro-scale ERT is a very effective tool to characterize subsoil conditions and monitor root zone activities, especially in terms of root zone suction regions. Micro-scale ERT can detect the main suction zones caused by the tree root activity, as demonstrated in the case of the apple orchard, while ERT and moisture measurements in the lagoon environment show a high resistivity suction layer located at root depth even during marsh flooding. Both observations will be important pieces of information for the comprehension of relevant eco- hydrological dynamics.

  20. How significant to plant N nutrition is the direct consumption of soil microbes by roots?

    PubMed Central

    Hill, Paul W; Marsden, Karina A; Jones, Davey L

    2013-01-01

    Summary –The high degree to which plant roots compete with soil microbes for organic forms of nitrogen (N) is becoming increasingly apparent. This has culminated in the finding that plants may consume soil microbes as a source of N, but the functional significance of this process remains unknown. –We used 15N- and 14C-labelled cultures of soil bacteria to measure rates of acquisition of microbes by sterile wheat roots and plants growing in soil. We compared these rates with acquisition of 15N delivered as nitrate, amino acid monomer (l-alanine) and short peptide (l-tetraalanine), and the rate of decomposition of [14C] microbes by indigenous soil microbiota. –Acquisition of microbe 15N by both sterile roots and roots growing in soil was one to two orders of magnitude slower than acquisition of all other forms of 15N. Decomposition of microbes was fast enough to account for all 15N recovered, but approximately equal recovery of microbe 14C suggests that microbes entered roots intact. –Uptake of soil microbes by wheat (Triticum aestivum) roots appears to take place in soil. If wheat is typical, the importance of this process to terrestrial N cycling is probably minor in comparison with fluxes of other forms of soil inorganic and organic N. PMID:23718181

  1. Selective chemical binding enhances cesium tolerance in plants through inhibition of cesium uptake

    NASA Astrophysics Data System (ADS)

    Adams, Eri; Chaban, Vitaly; Khandelia, Himanshu; Shin, Ryoung

    2015-03-01

    High concentrations of cesium (Cs+) inhibit plant growth but the detailed mechanisms of Cs+ uptake, transport and response in plants are not well known. In order to identify small molecules with a capacity to enhance plant tolerance to Cs+, chemical library screening was performed using Arabidopsis. Of 10,000 chemicals tested, five compounds were confirmed as Cs+ tolerance enhancers. Further investigation and quantum mechanical modelling revealed that one of these compounds reduced Cs+ concentrations in plants and that the imidazole moiety of this compound bound specifically to Cs+. Analysis of the analogous compounds indicated that the structure of the identified compound is important for the effect to be conferred. Taken together, Cs+ tolerance enhancer isolated here renders plants tolerant to Cs+ by inhibiting Cs+ entry into roots via specific binding to the ion thus, for instance, providing a basis for phytostabilisation of radiocesium-contaminated farmland.

  2. Striga parasitizes transgenic hairy roots of Zea mays and provides a tool for studying plant-plant interactions

    PubMed Central

    2012-01-01

    Background Striga species are noxious root hemi-parasitic weeds that debilitate cereal production in sub-Saharan Africa (SSA). Control options for Striga are limited and developing Striga resistant crop germplasm is regarded as the best and most sustainable control measure. Efforts to improve germplasm for Striga resistance by a non-Genetic Modification (GM) approach, for example by exploiting natural resistance, or by a GM approach are constrained by limited information on the biological processes underpinning host-parasite associations. Additionaly, a GM approach is stymied by lack of availability of candidate resistance genes for introduction into hosts and robust transformation methods to validate gene functions. Indeed, a majority of Striga hosts, the world’s most cultivated cereals, are recalcitrant to genetic transformation. In maize, the existing protocols for transformation and regeneration are tedious, lengthy, and highly genotype-specific with low efficiency of transformation. Results We used Agrobacterium rhizogenes strain K599 carrying a reporter gene construct, Green Fluorescent Protein (GFP), to generate transgenic composite maize plants that were challenged with the parasitic plant Striga hermonthica. Eighty five percent of maize plants produced transgenic hairy roots expressing GFP. Consistent with most hairy roots produced in other species, transformed maize roots exhibited a hairy root phenotype, the hallmark of A. rhizogenes mediated transformation. Transgenic hairy roots resulting from A. rhizogenes transformation were readily infected by S. hermonthica. There were no significant differences in the number and size of S. hermonthica individuals recovered from either transgenic or wild type roots. Conclusions This rapid, high throughput, transformation technique will advance our understanding of gene function in parasitic plant-host interactions. PMID:22720750

  3. Variation in Adult Plant Phenotypes and Partitioning among Seed and Stem-Borne Roots across Brachypodium distachyon Accessions to Exploit in Breeding Cereals for Well-Watered and Drought Environments1[OPEN

    PubMed Central

    2015-01-01

    Seedling roots enable plant establishment. Their small phenotypes are measured routinely. Adult root systems are relevant to yield and efficiency, but phenotyping is challenging. Root length exceeds the volume of most pots. Field studies measure partial adult root systems through coring or use seedling roots as adult surrogates. Here, we phenotyped 79 diverse lines of the small grass model Brachypodium distachyon to adults in 50-cm-long tubes of soil with irrigation; a subset of 16 lines was droughted. Variation was large (total biomass, ×8; total root length [TRL], ×10; and root mass ratio, ×6), repeatable, and attributable to genetic factors (heritabilities ranged from approximately 50% for root growth to 82% for partitioning phenotypes). Lines were dissected into seed-borne tissues (stem and primary seminal axile roots) and stem-borne tissues (tillers and coleoptile and leaf node axile roots) plus branch roots. All lines developed one seminal root that varied, with branch roots, from 31% to 90% of TRL in the well-watered condition. With drought, 100% of TRL was seminal, regardless of line because nodal roots were almost always inhibited in drying topsoil. Irrigation stimulated nodal roots depending on genotype. Shoot size and tillers correlated positively with roots with irrigation, but partitioning depended on genotype and was plastic with drought. Adult root systems of B. distachyon have genetic variation to exploit to increase cereal yields through genes associated with partitioning among roots and their responsiveness to irrigation. Whole-plant phenotypes could enhance gain for droughted environments because root and shoot traits are coselected. PMID:25975834

  4. Variation in Adult Plant Phenotypes and Partitioning among Seed and Stem-Borne Roots across Brachypodium distachyon Accessions to Exploit in Breeding Cereals for Well-Watered and Drought Environments.

    PubMed

    Chochois, Vincent; Vogel, John P; Rebetzke, Gregory J; Watt, Michelle

    2015-07-01

    Seedling roots enable plant establishment. Their small phenotypes are measured routinely. Adult root systems are relevant to yield and efficiency, but phenotyping is challenging. Root length exceeds the volume of most pots. Field studies measure partial adult root systems through coring or use seedling roots as adult surrogates. Here, we phenotyped 79 diverse lines of the small grass model Brachypodium distachyon to adults in 50-cm-long tubes of soil with irrigation; a subset of 16 lines was droughted. Variation was large (total biomass, ×8; total root length [TRL], ×10; and root mass ratio, ×6), repeatable, and attributable to genetic factors (heritabilities ranged from approximately 50% for root growth to 82% for partitioning phenotypes). Lines were dissected into seed-borne tissues (stem and primary seminal axile roots) and stem-borne tissues (tillers and coleoptile and leaf node axile roots) plus branch roots. All lines developed one seminal root that varied, with branch roots, from 31% to 90% of TRL in the well-watered condition. With drought, 100% of TRL was seminal, regardless of line because nodal roots were almost always inhibited in drying topsoil. Irrigation stimulated nodal roots depending on genotype. Shoot size and tillers correlated positively with roots with irrigation, but partitioning depended on genotype and was plastic with drought. Adult root systems of B. distachyon have genetic variation to exploit to increase cereal yields through genes associated with partitioning among roots and their responsiveness to irrigation. Whole-plant phenotypes could enhance gain for droughted environments because root and shoot traits are coselected. PMID:25975834

  5. Hydroponics--Studies in Plant Culture With Historical Roots.

    ERIC Educational Resources Information Center

    Lopez, Luz Maria

    1981-01-01

    Presents methods for demonstrating and applying scientific principles by growing plants through water culture (hydroponics), including a review of the history of hydroponics, re-creating some early experiments, and setting up a modern hydroponic system. (CS)

  6. Leguminous plants: inventors of root nodules to accommodate symbiotic bacteria.

    PubMed

    Suzaki, Takuya; Yoro, Emiko; Kawaguchi, Masayoshi

    2015-01-01

    Legumes and a few other plant species can establish a symbiotic relationship with nitrogen-fixing rhizobia, which enables them to survive in a nitrogen-deficient environment. During the course of nodulation, infection with rhizobia induces the dedifferentiation of host cells to form primordia of a symbiotic organ, the nodule, which prepares plants to accommodate rhizobia in host cells. While these nodulation processes are known to be genetically controlled by both plants and rhizobia, recent advances in studies on two model legumes, Lotus japonicus and Medicago truncatula, have provided great insight into the underlying plant-side molecular mechanism. In this chapter, we review such knowledge, with particular emphasis on two key processes of nodulation, nodule development and rhizobial invasion. PMID:25805123

  7. Polar transport of auxin across gravistimulated roots of maize and its enhancement by calcium

    NASA Technical Reports Server (NTRS)

    Lee, J. S.; Evans, M. L.

    1985-01-01

    The effect of Ca on the polar movement of [3H]indoleacetic acid ([3H]IAA) in gravistimulated roots was examined using 3-day-old seedlings of maize (Zea mays L.). Transport of label was measured by placing an agar donor block containing [3H]IAA on one side of the elongation zone and measuring movement of label across the root into an agar receiver block on the opposite side. In vertically oriented roots, movement of label across the elongation zone into the receiver was slight and was not enhanced by incorporating 10 millimolar CaCl2 into the receiver block. In horizontally oriented roots, movement of label across the root was readily detectable and movement to a receiver on the bottom was about 3-fold greater than movement in the opposite direction. This polarity was abolished in roots from which the caps were removed prior to gravistimulation. When CaCl2 was incorporated into the receivers, movement of label across horizontally oriented intact roots was increased about 3-fold in both the downward and upward direction. The ability of Ca to enhance the movement of label from [3H]IAA increased with increasing Ca concentration in the receiver up to 5 to 10 millimolar CaCl2. With the inclusion of CaCl2 in the receiver blocks, gravity-induced polar movement of label into receiver blocks from applied [3H]IAA was detectable within 30 minutes, and asymmetric distribution of label within the tissue was detectable within 20 minutes. The results indicate that gravistimulation induces a physiological asymmetry in the auxin transport system of maize roots and that Ca increases the total transport of auxin across the root.

  8. Getting to the root of plant iron uptake and cell-cell transport: Polarity matters!

    PubMed Central

    Dubeaux, Guillaume; Zelazny, Enric; Vert, Grégory

    2015-01-01

    Plasma membrane proteins play pivotal roles in mediating responses to endogenous and environmental cues. Regulation of membrane protein levels and establishment of polarity are fundamental for many cellular processes. In plants, IRON-REGULATED TRANSPORTER 1 (IRT1) is the major root iron transporter but is also responsible for the absorption of other divalent metals such as manganese, zinc and cobalt. We recently uncovered that IRT1 is polarly localized to the outer plasma membrane domain of plant root epidermal cells upon depletion of its secondary metal substrates. The endosome-recruited FYVE1 protein interacts with IRT1 in the endocytic pathway and plays a crucial role in the establishment of IRT1 polarity, likely through its recycling to the cell surface. Our work sheds light on the mechanisms of radial transport of nutrients across the different cell types of plant roots toward the vascular tissues and raises interesting parallel with iron transport in mammals. PMID:26479146

  9. Sensitivity of greenhouse summer dryness to changes in plant rooting characteristics

    USGS Publications Warehouse

    Milly, P.C.D.

    1997-01-01

    A possible consequence of increased concentrations of greenhouse gases in Earth's atmosphere is "summer dryness," a decrease of summer plant-available soil water in middle latitudes, caused by increased availability of energy to drive evapotranspiration. Results from a numerical climate model indicate that summer dryness and related changes of land-surface water balances are highly sensitive to possible concomitant changes of plant-available water-holding capacity of soil, which depends on plant rooting depth and density. The model suggests that a 14% decrease of the soil volume whose water is accessible to plant roots would generate the same summer dryness, by one measure, as an equilibrium doubling of atmospheric carbon dioxide. Conversely, a 14% increase of that soil volume would be sufficient to offset the summer dryness associated with carbon-dioxide doubling. Global and regional changes in rooting depth and density may result from (1) plant and plant-community responses to greenhouse warming, to carbon-dioxide fertilization, and to associated changes in the water balance and (2) anthropogenic deforestation and desertification. Given their apparently critical role, heretofore ignored, in global hydroclimatic change, such changes of rooting characteristics should be carefully evaluated using ecosystem observations, theory, and models.

  10. Breeding crop plants with deep roots: their role in sustainable carbon, nutrient and water sequestration

    PubMed Central

    Kell, Douglas B.

    2011-01-01

    Background The soil represents a reservoir that contains at least twice as much carbon as does the atmosphere, yet (apart from ‘root crops’) mainly just the above-ground plant biomass is harvested in agriculture, and plant photosynthesis represents the effective origin of the overwhelming bulk of soil carbon. However, present estimates of the carbon sequestration potential of soils are based more on what is happening now than what might be changed by active agricultural intervention, and tend to concentrate only on the first metre of soil depth. Scope Breeding crop plants with deeper and bushy root ecosystems could simultaneously improve both the soil structure and its steady-state carbon, water and nutrient retention, as well as sustainable plant yields. The carbon that can be sequestered in the steady state by increasing the rooting depths of crop plants and grasses from, say, 1 m to 2 m depends significantly on its lifetime(s) in different molecular forms in the soil, but calculations (http://dbkgroup.org/carbonsequestration/rootsystem.html) suggest that this breeding strategy could have a hugely beneficial effect in stabilizing atmospheric CO2. This sets an important research agenda, and the breeding of plants with improved and deep rooting habits and architectures is a goal well worth pursuing. PMID:21813565

  11. Shoot-to-Root Mobile Transcription Factor HY5 Coordinates Plant Carbon and Nitrogen Acquisition.

    PubMed

    Chen, Xiangbin; Yao, Qinfang; Gao, Xiuhua; Jiang, Caifu; Harberd, Nicholas P; Fu, Xiangdong

    2016-03-01

    Coordination of shoot photosynthetic carbon fixation with root inorganic nitrogen uptake optimizes plant performance in a fluctuating environment [1]. However, the molecular basis of this long-distance shoot-root coordination is little understood. Here we show that Arabidopsis ELONGATED HYPOCOTYL5 (HY5), a bZIP transcription factor that regulates growth in response to light [2, 3], is a shoot-to-root mobile signal that mediates light promotion of root growth and nitrate uptake. Shoot-derived HY5 auto-activates root HY5 and also promotes root nitrate uptake by activating NRT2.1, a gene encoding a high-affinity nitrate transporter [4]. In the shoot, HY5 promotes carbon assimilation and translocation, whereas in the root, HY5 activation of NRT2.1 expression and nitrate uptake is potentiated by increased carbon photoassimilate (sucrose) levels. We further show that HY5 function is fluence-rate modulated and enables homeostatic maintenance of carbon-nitrogen balance in different light environments. Thus, mobile HY5 coordinates light-responsive carbon and nitrogen metabolism, and hence shoot and root growth, in a whole-organismal response to ambient light fluctuations. PMID:26877080

  12. First evidence of root morphological and architectural variations in young Posidonia oceanica plants colonizing different substrate typologies

    NASA Astrophysics Data System (ADS)

    Balestri, Elena; de Battisti, Davide; Vallerini, Flavia; Lardicci, Claudio

    2015-03-01

    Root morphology and root system architecture of young Posidonia oceanica plants established on two contrasting substrate types, sand and rock, were examined to provide insights into the strategy of adaptation of seagrasses to their environment. After germination, seedlings were planted on sandy patches and on rock within the same area, and survived plants were collected five years later for measurements of the size of the entire root complex and analysis of individual morphological and architectural root traits. Collected plants exhibited up to nine highly intermingled root systems and approx. 2.5 m of total root length. Maximum horizontal extension, total biomass and total length of roots were not significantly affected by substrate. However, on sand roots grew vertically reaching up to 13 cm, while on rock they extended more horizontally and did not penetrate deeper than 5-7 cm leading to the formation of a shallow, densely packed root complex. On rock, the number and the length of second-order laterals on an individual root system were reduced and the topological index higher than on sand (0.8 vs. 0.7) reflecting a more simple (herringbone) branching pattern. Again, root diameter was greater than on sand. The results suggest that P. oceanica can adjust root traits early during plant development according to substrate typology to maximize anchorage and substrate exploration efficiency. This plasticity enables the species to establish and persist also on rocky bottoms which generally prevent establishment of the majority of seagrasses.

  13. Actin Cytoskeleton-Based Plant Synapse as Gravitransducer in the Transition Zone of the Root Apex

    NASA Astrophysics Data System (ADS)

    Baluska, Frantisek; Barlow, Peter; Volkmann, Dieter; Mancuso, Stefano

    The actin cytoskeleton was originally proposed to act as the signal transducer in the plant gravity sensory-motoric circuit. Surprisingly, however, several studies have documented that roots perfom gravisensing and gravitropism more effectively if exposed to diverse anti-F-actin drugs. Our study, using decapped maize root apices, has revealed that depolymerization of F-actin stimulates gravity perception in cells of the transition zone where root gravitropism is initiated (Mancuso et al. 2006). It has been proposed (Balǔka et al. 2005, 2009a) that s the non-growing adhesive end-poles, enriched with F-actin and myosin VIII, and active in endocytic recycling of both PIN transporters and cell wall pectins cross-linked with calcium and boron, act as the gravisensing domains, and that these impinge directly upon the root motoric responses via control of polar auxin transport. This model suggests that mechanical asymmetry at these plant synapses determines vectorial gravity-controlled auxin transport. Due to the gravity-imposed mechanical load upon the protoplast, a tensional stress is also imposed upon the plasma membrane of the physically lower synaptic cell pole. This stress is then relieved by shifting the endocytosis-exocytosis balance towards exocytosis (Balǔka et al. s 2005, 2009a,b). This `Synaptic Auxin Secretion' hypothesis does not conflict with the `Starch Statolith' hypothesis, which is based on amyloplast sedimentation. In fact, the `Synaptic Auxin Secretion' hypothesis has many elements which allow its unification with the Starch-Statolith model (Balǔka et al. 2005, 2009a,b). s References Balǔka F, Volkmann D, Menzel D (2005) Plant synapses: actin-based adhesion s domains for cell-to-cell communication. Trends Plant Sci 10: 106-111 Balǔka F, Schlicht M, s Wan Y-L, Burbach C, Volkmann D (2009a) Intracellular domains and polarity in root apices: from synaptic domains to plant neurobiology. Nova Acta Leopoldina 96: 103-122 Balǔka s F, Mancuso S

  14. Effect of Root-Zone Moisture Variations on Growth of Lettuce and Pea Plants

    NASA Astrophysics Data System (ADS)

    Ilieva, Iliana; Ivanova, Tania

    2008-06-01

    Variations in substrate moisture lead to changes in water and oxygen availability to plant roots. Ground experiments were carried out in the laboratory prototype of SVET-2 Space Greenhouse to study the effect of variation of root-zone moisture conditions on growth of lettuce and pea plants. The effect of transient increase (for 1 day) and drastic increase (waterlogging for 10 days) of substrate moisture was studied with 16-day old pea and 21-day old lettuce plants respectively. Pea height and fresh biomass accumulation were not affected by transient substrate moisture increase. Net photosynthetic rate (Pn) of pea plants showed fast response to substrate moisture variation, while chlorophyll content did not change. Drastic change of substrate moisture suppressed lettuce Pn, chlorophyll biosynthesis and plant growth. These parameters slowly recovered after termination of waterlogging treatment but lettuce yield was greatly affected. The results showed that the most sensitive physiological parameter to substrate moisture variations is photosynthesis.

  15. Molecular responses in root-associative rhizospheric bacteria to variations in plant exudates

    NASA Astrophysics Data System (ADS)

    Abdoun, Hamid; McMillan, Mary; Pereg, Lily

    2015-04-01

    Plant exudates are a major factor in the interface of plant-soil-microbe interactions and it is well documented that the microbial community structure in the rhizosphere is largely influenced by the particular exudates excreted by various plants. Azospirillum brasilense is a plant growth promoting rhizobacterium that is known to interact with a large number of plants, including important food crops. The regulatory gene flcA has an important role in this interaction as it controls morphological differentiation of the bacterium that is essential for attachment to root surfaces. Being a response regulatory gene, flcA mediates the response of the bacterial cell to signals from the surrounding rhizosphere. This makes this regulatory gene a good candidate for analysis of the response of bacteria to rhizospheric alterations, in this case, variations in root exudates. We will report on our studies on the response of Azospirillum, an ecologically, scientifically and agriculturally important bacterial genus, to variations in the rhizosphere.

  16. The Roots of Defense: Plant Resistance and Tolerance to Belowground Herbivory

    PubMed Central

    Watts, Sean M.; Dodson, Craig D.; Reichman, O. J.

    2011-01-01

    Background There is conclusive evidence that there are fitness costs of plant defense and that herbivores can drive selection for defense. However, most work has focused on above-ground interactions, even though belowground herbivory may have greater impacts on individual plants than above-ground herbivory. Given the role of belowground plant structures in resource acquisition and storage, research on belowground herbivores has much to contribute to theories on the evolution of plant defense. Pocket gophers (Geomyidae) provide an excellent opportunity to study root herbivory. These subterranean rodents spend their entire lives belowground and specialize on consuming belowground plant parts. Methodology and Principal Findings We compared the root defenses of native forbs from mainland populations (with a history of gopher herbivory) to island populations (free from gophers for up to 500,000 years). Defense includes both resistance against herbivores and tolerance of herbivore damage. We used three approaches to compare these traits in island and mainland populations of two native California forbs: 1) Eschscholzia californica populations were assayed to compare alkaloid deterrents, 2) captive gophers were used to test the palatability of E. californica roots and 3) simulated root herbivory assessed tolerance to root damage in Deinandra fasciculata and E. californica. Mainland forms of E. californica contained 2.5 times greater concentration of alkaloids and were less palatable to gophers than island forms. Mainland forms of D. fasciculata and, to a lesser extent, E. californica were also more tolerant of root damage than island conspecifics. Interestingly, undamaged island individuals of D. fasciculata produced significantly more fruit than either damaged or undamaged mainland individuals. Conclusions and Significance These results suggest that mainland plants are effective at deterring and tolerating pocket gopher herbivory. Results also suggest that both forms of

  17. [Difference of anti-fracture mechanical characteristics between lateral-root branches and adjacent upper straight roots of four plant species in vigorous growth period].

    PubMed

    Liu, Peng-fei; Liu, Jing; Zhu, Hong-hui; Zhang, Xin; Zhang, Ge; Li, You-fang; Su, Yu; Wang, Chen-jia

    2016-01-01

    Taking four plant species, Caragana korshinskii, Salix psammophila, Hippophae rhamnides and Artemisia sphaerocephala, which were 3-4 years old and in vigorous growth period, as test materials, the anti-fracture forces of lateral-root branches and adjacent upper straight roots were measured with the self-made fixture and the instrument of TY 8000. The lateral-root branches were vital and the diameters were 1-4 mm. The results showed that the anti-fracture force and anti-fracture strength of lateral-root branches were lesser than those of the adjacent upper straight roots even though the average diameter of lateral-root branches was greater. The ratios of anti-fracture strength of lateral-root branches to the adjacent upper straight roots were 71.5% for C. korshinskii, 62.9% for S. psammophila, 45.4% for H. rhamnides and 35.4% for A. sphaerocephala. For the four plants, the anti-fracture force positively correlated with the diameter in a power function, while the anti-fracture strength negatively correlated with diameter in a power function. The anti-fracture strengths of lateral-root branches and adjacent upper straight roots for the four species followed the sequence of C. korshinskii (33.66 and 47.06 MPa) > S. psammophila (17.31 and 27.54 MPa) > H. rhamnides (3.97 and 8.75 MPa) > A. sphaerphala (2.18 and 6.15 MPa). PMID:27228590

  18. The mitochondrial malate dehydrogenase 1 gene GhmMDH1 is involved in plant and root growth under phosphorus deficiency conditions in cotton

    PubMed Central

    Wang, Zhi-An; Li, Qing; Ge, Xiao-Yang; Yang, Chun-Lin; Luo, Xiao-Li; Zhang, An-Hong; Xiao, Juan-Li; Tian, Ying-Chuan; Xia, Gui-Xian; Chen, Xiao-Ying; Li, Fu-Guang; Wu, Jia-He

    2015-01-01

    Cotton, an important commercial crop, is cultivated for its natural fibers, and requires an adequate supply of soil nutrients, including phosphorus, for its growth. Soil phosporus exists primarily in insoluble forms. We isolated a mitochondrial malate dehydrogenase (MDH) gene, designated as GhmMDH1, from Gossypium hirsutum L. to assess its effect in enhancing P availability and absorption. An enzyme kinetic assay showed that the recombinant GhmMDH1 possesses the capacity to catalyze the interconversion of oxaloacetate and malate. The malate contents in the roots, leaves and root exudates was significantly higher in GhmMDH1-overexpressing plants and lower in knockdown plants compared with the wild-type control. Knockdown of GhmMDH1 gene resulted in increased respiration rate and reduced biomass whilst overexpression of GhmMDH1 gave rise to decreased respiration rate and higher biomass in the transgenic plants. When cultured in medium containing only insoluble phosphorus, Al-phosphorus, Fe-phosphorus, or Ca-phosphorus, GhmMDH1-overexpressing plants produced significantly longer roots and had a higher biomass and P content than WT plants, however, knockdown plants showed the opposite results for these traits. Collectively, our results show that GhmMDH1 is involved in plant and root growth under phosphorus deficiency conditions in cotton, owing to its functions in leaf respiration and P acquisition. PMID:26179843

  19. The mitochondrial malate dehydrogenase 1 gene GhmMDH1 is involved in plant and root growth under phosphorus deficiency conditions in cotton.

    PubMed

    Wang, Zhi-An; Li, Qing; Ge, Xiao-Yang; Yang, Chun-Lin; Luo, Xiao-Li; Zhang, An-Hong; Xiao, Juan-Li; Tian, Ying-Chuan; Xia, Gui-Xian; Chen, Xiao-Ying; Li, Fu-Guang; Wu, Jia-He

    2015-01-01

    Cotton, an important commercial crop, is cultivated for its natural fibers, and requires an adequate supply of soil nutrients, including phosphorus, for its growth. Soil phosporus exists primarily in insoluble forms. We isolated a mitochondrial malate dehydrogenase (MDH) gene, designated as GhmMDH1, from Gossypium hirsutum L. to assess its effect in enhancing P availability and absorption. An enzyme kinetic assay showed that the recombinant GhmMDH1 possesses the capacity to catalyze the interconversion of oxaloacetate and malate. The malate contents in the roots, leaves and root exudates was significantly higher in GhmMDH1-overexpressing plants and lower in knockdown plants compared with the wild-type control. Knockdown of GhmMDH1 gene resulted in increased respiration rate and reduced biomass whilst overexpression of GhmMDH1 gave rise to decreased respiration rate and higher biomass in the transgenic plants. When cultured in medium containing only insoluble phosphorus, Al-phosphorus, Fe-phosphorus, or Ca-phosphorus, GhmMDH1-overexpressing plants produced significantly longer roots and had a higher biomass and P content than WT plants, however, knockdown plants showed the opposite results for these traits. Collectively, our results show that GhmMDH1 is involved in plant and root growth under phosphorus deficiency conditions in cotton, owing to its functions in leaf respiration and P acquisition. PMID:26179843

  20. Promise for plant pest control: root-associated pseudomonads with insecticidal activities

    PubMed Central

    Kupferschmied, Peter; Maurhofer, Monika; Keel, Christoph

    2013-01-01

    Insects are an important and probably the most challenging pest to control in agriculture, in particular when they feed on belowground parts of plants. The application of synthetic pesticides is problematic owing to side effects on the environment, concerns for public health and the rapid development of resistance. Entomopathogenic bacteria, notably Bacillus thuringiensis and Photorhabdus/Xenorhabdus species, are promising alternatives to chemical insecticides, for they are able to efficiently kill insects and are considered to be environmentally sound and harmless to mammals. However, they have the handicap of showing limited environmental persistence or of depending on a nematode vector for insect infection. Intriguingly, certain strains of plant root-colonizing Pseudomonas bacteria display insect pathogenicity and thus could be formulated to extend the present range of bioinsecticides for protection of plants against root-feeding insects. These entomopathogenic pseudomonads belong to a group of plant-beneficial rhizobacteria that have the remarkable ability to suppress soil-borne plant pathogens, promote plant growth, and induce systemic plant defenses. Here we review for the first time the current knowledge about the occurrence and the molecular basis of insecticidal activity in pseudomonads with an emphasis on plant-beneficial and prominent pathogenic species. We discuss how this fascinating Pseudomonas trait may be exploited for novel root-based approaches to insect control in an integrated pest management framework. PMID:23914197

  1. Enhanced Mulberroside A Production from Cell Suspension and Root Cultures of Morus alba Using Elicitation.

    PubMed

    Komaikul, Jukrapun; Kitisripanya, Tharita; Tanaka, Hiroyuki; Sritularak, Boonchoo; Putalun, Waraporn

    2015-07-01

    Morus alba L. has been used in Asian traditional medicine as an anti-inflammatory, anti-asthmatic, anthelmintic and as a whitening agent in cosmetic products. Mulberroside A is the major active compound from M. alba root bark. In this study, cell suspension and root cultures of M. alba were established, and the effect of the elicitors on the enhancement of mulberroside A production in M. alba was investigated. The cell suspension and root cultures of M. alba were exposed to elicitors and then mulberroside A contents were determined by an indirect competitive ELISA method. High levels of mulberroside A were obtained by addition of 100 and 200 μM salicylic acid with 24 h exposure time in cell suspension cultures (37.9 ± 1.5 and 34.0 ± 4.7 mg/g dry wt., respectively). Furthermore, addition of yeast extract at 2 mg/mL with 24 h exposure time can significantly increase mulberroside A contents from both cell suspension (3.2-fold) and root cultures (6.6-fold). Mulberroside A contents from both cell suspension and root cultures after treatment with elicitors are similar or higher than those found in the intact root and root bark of several years old M. alba. These results indicate that mulberry tissue cultures using the elicitation method are interesting alternative sources for mulberroside A production. PMID:26411024

  2. Combining fuzzy set theory and nonlinear stretching enhancement for unsupervised classification of cotton root rot

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cotton root rot is a destructive disease affecting cotton production. Accurate identification of infected areas within fields is useful for cost-effective control of the disease. The uncertainties caused by various infection stages and newly infected plants make it difficult to achieve accurate clas...

  3. Arbuscular mycorrhizal assemblages in native plant roots change in the presence of invasive exotic grasses

    USGS Publications Warehouse

    Hawkes, C.V.; Belnap, J.; D'Antonio, C.; Firestone, M.K.

    2006-01-01

    Plant invasions have the potential to significantly alter soil microbial communities, given their often considerable aboveground effects. We examined how plant invasions altered the arbuscular mycorrhizal fungi of native plant roots in a grassland site in California and one in Utah. In the California site, we used experimentally created plant communities composed of exotic (Avena barbata, Bromus hordeaceus) and native (Nassella pulchra, Lupinus bicolor) monocultures and mixtures. In the Utah semi-arid grassland, we took advantage of invasion by Bromus tectorum into long-term plots dominated by either of two native grasses, Hilaria jamesii or Stipa hymenoides. Arbuscular mycorrhizal fungi colonizing roots were characterized with PCR amplification of the ITS region, cloning, and sequencing. We saw a significant effect of the presence of exotic grasses on the diversity of mycorrhizal fungi colonizing native plant roots. In the three native grasses, richness of mycorrhizal fungi decreased; in the native forb at the California site, the number of fungal RFLP patterns increased in the presence of exotics. The exotic grasses also caused the composition of the mycorrhizal community in native roots to shift dramatically both in California, with turnover of Glomus spp., and Utah, with replacement of Glomus spp. by apparently non-mycorrhizal fungi. Invading plants may be able to influence the network of mycorrhizal fungi in soil that is available to natives through either earlier root activity or differential carbon provision compared to natives. Alteration of the soil microbial community by plant invasion can provide a mechanism for both successful invasion and the resulting effects of invaders on the ecosystem. ?? Springer 2006.

  4. The Production and Release of Living Root Cap Border Cells is a Function of Root Apical Meristem Type in Dicotyledonous Angiosperm Plants

    PubMed Central

    HAMAMOTO, LESLEY; HAWES, MARTHA C.; ROST, THOMAS L.

    2006-01-01

    • Background and Aims The root apical meristems (RAM) of flowering plant roots are organized into recognizable pattern types. At present, there are no known ecological or physiological benefits to having one RAM organization type over another. Although there are phylogenetic distribution patterns in plant groups, the possible evolutionary advantages of different RAM organization patterns are not understood. Root caps of many flowering plant roots are known to release living border cells into the rhizosphere, where the cells are believed to have the capacity to alter conditions in the soil and to interact with soil micro-organisms. Consequently, high rates of border cell production may have the potential to benefit plant growth and development greatly, and to provide a selective advantage in certain soil environments. This study reports the use of several approaches to elucidate the anatomical and developmental relationships between RAM organization and border cell production. • Methods RAM types from many species were compared with numbers of border cells released in those species. In addition, other species were grown, fixed and sectioned to verify their organization type and capacity to produce border cells. Root tips were examined microscopically to characterize their pattern and some were stained to determine the viability of root cap cells. • Key Results The first report of a correlation between RAM organization type and the production and release of border cells is provided: species exhibiting open RAM organization produce significantly more border cells than species exhibiting closed apical organization. Roots with closed apical organization release peripheral root cap cells in sheets or large groups of dead cells, whereas root caps with open organization release individual living border cells. • Conclusions This study, the first to document a relationship between RAM organization, root cap behaviour and a possible ecological benefit to the plant

  5. Ericoid mycorrhizal fungi are common root associates of a Mediterranean ectomycorrhizal plant (Quercus ilex).

    PubMed

    Bergero, R; Perotto, S; Girlanda, M; Vidano, G; Luppi, A M

    2000-10-01

    Mycorrhiza samples of neighbouring Quercus ilex and Erica arborea plants collected in a postcutting habitat were processed to see whether plants differing in mycorrhizal status harbour the same root endophytes. Three experiments were performed in parallel: (i) isolation, identification and molecular characterization of fungi from surface-sterilized roots of both plant species; (ii) re-inoculation of fungal isolates on axenic E. arborea and Q. ilex seedlings; (iii) direct inoculation of field-collected Q. ilex ectomycorrhizas onto E. arborea seedlings. About 70 and 150 fungal isolates were obtained from roots of Q. ilex and E. arborea, respectively. Among them, Oidiodendron species and five cultural morphotypes of sterile isolates formed typical ericoid mycorrhizas on E. arborea in vitro. Fungi with such mycorrhizal ability were derived from both host plants. Isolates belonging to one of these morphotypes (sd9) also exhibited an unusual pattern of colonization, with an additional extracellular hyphal net. Ericoid mycorrhizas were also readily obtained by direct inoculation of E. arborea seedlings with Q. ilex ectomycorrhizal tips. Polymerase chain-restriction fragment length polymorphism and random amplified polymorphic DNA analyses of the shared sterile morphotypes demonstrate, in the case of sd9, the occurrence of the same genet on the two host plants. These results indicate that ericoid mycorrhizal fungi associate with ectomycorrhizal roots, and the ecological significance of this finding is discussed. PMID:11050558

  6. Root phototropism: how light and gravity interact in shaping plant form

    NASA Technical Reports Server (NTRS)

    Kiss, John Z.; Correll, Melanie J.; Mullen, Jack L.; Hangarter, Roger P.; Edelmann, Richard E.

    2003-01-01

    The interactions among tropisms can be critical in determining the final growth form of plants and plant organs. We have studied tropistic responses in roots as an example of these type of interactions. While gravitropism is the predominant tropistic response in roots, phototropism also plays a role in the oriented growth in this organ in flowering plants. In blue or white light, roots exhibit negative phototropism, but red light induces positive phototropism. In the flowering plant Arabidopsis, the photosensitive pigments phytochrome A (phyA) and phytochrome B (phyB) mediate this positive red-light-based photoresponse in roots since single mutants (and the double phyAB mutant) were severely impaired in this response. While blue-light-based negative phototropism is primarily mediated by the phototropin family of photoreceptors, the phyA and phyAB mutants (but not phyB) were inhibited in this response relative to the WT. The differences observed in phototropic responses were not due to growth limitations since the growth rates among all the mutants tested were not significantly different from that of the WT. Thus, our study shows that the blue-light and red-light systems interact in plants and that phytochrome plays a key role in integrating multiple environmental stimuli.

  7. Using Three-dimensional Plant Root Architecture in Models of Shallow-slope Stability

    PubMed Central

    Danjon, Frédéric; Barker, David H.; Drexhage, Michael; Stokes, Alexia

    2008-01-01

    Background The contribution of vegetation to shallow-slope stability is of major importance in landslide-prone regions. However, existing slope stability models use only limited plant root architectural parameters. This study aims to provide a chain of tools useful for determining the contribution of tree roots to soil reinforcement. Methods Three-dimensional digitizing in situ was used to obtain accurate root system architecture data for mature Quercus alba in two forest stands. These data were used as input to tools developed, which analyse the spatial position of roots, topology and geometry. The contribution of roots to soil reinforcement was determined by calculating additional soil cohesion using the limit equilibrium model, and the factor of safety (FOS) using an existing slope stability model, Slip4Ex. Key Results Existing models may incorrectly estimate the additional soil cohesion provided by roots, as the spatial position of roots crossing the potential slip surface is usually not taken into account. However, most soil reinforcement by roots occurs close to the tree stem and is negligible at a distance >1·0 m from the tree, and therefore global values of FOS for a slope do not take into account local slippage along the slope. Conclusions Within a forest stand on a landslide-prone slope, soil fixation by roots can be minimal between uniform rows of trees, leading to local soil slippage. Therefore, staggered rows of trees would improve overall slope stability, as trees would arrest the downward movement of soil. The chain of tools consisting of both software (free for non-commercial use) and functions available from the first author will enable a more accurate description and use of root architectural parameters in standard slope stability analyses. PMID:17766845

  8. Cell wall compositional changes during incubation of plant roots measured by mid-infrared diffuse reflectance spectroscopy and fiber analysis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Plant roots, particularly the constituents of root cell walls (hemicellulose, cellulose and lignin), are important contributors to soil organic matter. Little is known about the cell wall composition of many important crop species or compositional changes as roots decay. The objectives of this stu...

  9. Enhanced Cd2+ -selective root-tonoplast-transport in tobaccos expressing Arabidopsis cation exchangers.

    PubMed

    Koren'kov, V; Park, S; Cheng, N-H; Sreevidya, C; Lachmansingh, J; Morris, J; Hirschi, K; Wagner, G J

    2007-01-01

    Several Arabidopsis CAtion eXchangers (CAXs) encode tonoplast-localized transporters that appear to be major contributors to vacuolar accumulation/sequestration of cadmium (Cd(2+)), an undesirable pollutant ion that occurs in man largely as a result of dietary consumption of aerial tissues of food plants. But, ion-selectivity of individual CAX transporter types remains largely unknown. Here, we transformed Nicotiana tabacum with several CAX genes driven by the Cauliflower Mosaic Virus (CaMV) 35S promoter and monitored divalent cation transport in root-tonoplast vesicles from these plants in order to select particular CAX genes directing high Cd(2+) antiporter activity in root tonoplast. Comparison of seven different CAX genes indicated that all transported Cd(2+), Ca(2+), Zn(2+), and Mn(2+) to varying degrees, but that CAX4 and CAX2 had high Cd(2+) transport and selectivity in tonoplast vesicles. CAX4 driven by the CaMV 35S and FS3 [figwort mosaic virus (FMV)] promoters increased the magnitude and initial rate of Cd(2+)/H(+) exchange in root-tonoplast vesicles. Ion selectivity of transport in root-tonoplast vesicles isolated from FS3::CAX4-expressing plant lines having a range of gene expression was Cd(2+)>Zn(2+)>Ca(2+)>Mn(2+) and the ratios of maximal Cd(2+) (and Zn(2+)) versus maximal Ca(2+) and Mn(2+) transport were correlated with the levels of CAX4 expression. Root Cd accumulation in high CAX4 and CAX2 expressing lines was increased in seedlings grown with 0.02 muM Cd. These observations are consistent with a model in which expression of an Arabidopsis-gene-encoded, Cd(2+)-efficient antiporter in host plant roots results in greater root vacuole Cd(2+) transport activity, increased root Cd accumulation, and a shift in overall root tonoplast ion transport selectivity towards higher Cd(2+) selectivity. Results support a model in which certain CAX antiporters are somewhat more selective for particular divalent cations. PMID:16845524

  10. The Mechanics and Energetics of Soil Bioturbation by Plant Roots and Earthworms - Plastic Deformation Considerations

    NASA Astrophysics Data System (ADS)

    Ruiz, Siul; Or, Dani; Schymanski, Stanislaus

    2014-05-01

    Soil structure plays a critical factor in the agricultural, hydrological and ecological functions of soils. These services are adversely impacted by soil compaction, a damage that could last for many years until functional structure is restored. An important class of soil structural restoration processes are related to biomechanical activity associated with burrowing of earthworms and root proliferation in impacted soil volumes. We study details of the mechanical processes and energetics associated with quantifying the rates and mechanical energy required for soil structural restoration. We first consider plastic cavity expansion to describe earthworm and plant root radial expansion under various conditions. We then use cone penetration models as analogues to wedging induced by root tip growth and worm locomotion. The associated mechanical stresses and strains determine the mechanical energy associated with bioturbation for different hydration conditions and root/earthworm geometries. Results illustrate a reduction in strain energy with increasing water content and trade-offs between pressure and energy investment for various root and earthworm geometries. The study provides the basic building blocks for estimating rates of soil structural alteration, the associated energetic requirements (soil carbon, plant assimilates) needed to sustain structure regeneration by earthworms and roots, and highlights potential mechanical cut-offs for such activities.

  11. Responses of Rat Root ( Raf.) Plants to Salinity and pH Conditions.

    PubMed

    Calvo-Polanco, Monica; Alejandra Equiza, María; Señorans, Jorge; Zwiazek, Janusz J

    2014-03-01

    Growth and physiological parameters were examined in rat root ( Raf.) plants grown under controlled environment conditions in hydroponics and subjected to different pH and salinity treatments to determine whether these environmental factors may contribute to poor establishment of in oil sands constructed wetlands. When plants were subjected to a root zone pH ranging from 6.0 to 9.5, the plants that were growing at pH 7.0 showed the highest relative growth rates and chlorophyll concentrations compared with lower and higher pH levels. The greatest inhibition of growth occurred at pH ranging from 8.0 to 9.5. High pH also triggered significant reductions in tissue concentrations of N, P, and microelements, whereas the concentrations of Mg increased at pH >8. When NaCl (25, 50, and 100 mmol L) was added to the nutrient solution at pH 7.0 and 8.5, higher mortality and greater tissue concentrations of Na and Cl were measured in plants growing at pH 8.5 compared with pH 7.0. The results show that plants growing at the optimum pH of 7.0 can better tolerate salinity compared with plants exposed to high root zone pH. Both pH and salinity may present important environmental constraints to growth and establishment of plants in oil sands constructed wetlands. PMID:25602659

  12. Spatial distribution of enzyme activities along the root and in the rhizosphere of different plants

    NASA Astrophysics Data System (ADS)

    Razavi, Bahar S.; Zarebanadkouki, Mohsen; Blagodatskaya, Evgenia; Kuzyakov, Yakov

    2015-04-01

    Extracellular enzymes are important for decomposition of many biological macromolecules abundant in soil such as cellulose, hemicelluloses and proteins. Activities of enzymes produced by both plant roots and microbes are the primary biological drivers of organic matter decomposition and nutrient cycling. So far acquisition of in situ data about local activity of different enzymes in soil has been challenged. That is why there is an urgent need in spatially explicit methods such as 2-D zymography to determine the variation of enzymes along the roots in different plants. Here, we developed further the zymography technique in order to quantitatively visualize the enzyme activities (Spohn and Kuzyakov, 2013), with a better spatial resolution We grew Maize (Zea mays L.) and Lentil (Lens culinaris) in rhizoboxes under optimum conditions for 21 days to study spatial distribution of enzyme activity in soil and along roots. We visualized the 2D distribution of the activity of three enzymes:β-glucosidase, leucine amino peptidase and phosphatase, using fluorogenically labelled substrates. Spatial resolution of fluorescent images was improved by direct application of a substrate saturated membrane to the soil-root system. The newly-developed direct zymography shows different pattern of spatial distribution of enzyme activity along roots and soil of different plants. We observed a uniform distribution of enzyme activities along the root system of Lentil. However, root system of Maize demonstrated inhomogeneity of enzyme activities. The apical part of an individual root (root tip) in maize showed the highest activity. The activity of all enzymes was the highest at vicinity of the roots and it decreased towards the bulk soil. Spatial patterns of enzyme activities as a function of distance from the root surface were enzyme specific, with highest extension for phosphatase. We conclude that improved zymography is promising in situ technique to analyze, visualize and quantify

  13. Enhanced regeneration and functional recovery after spinal root avulsion by manipulation of the proteoglycan receptor PTPσ

    PubMed Central

    Li, Heng; Wong, Connie; Li, Wen; Ruven, Carolin; He, Liumin; Wu, Xiaoli; Lang, Bradley T.; Silver, Jerry; Wu, Wutian

    2015-01-01

    Following root avulsion, spinal nerves are physically disconnected from the spinal cord. Severe motoneuron death and inefficient axon regeneration often result in devastating motor dysfunction. Newly formed axons need to extend through inhibitory scar tissue at the CNS-PNS transitional zone before entering into a pro-regenerative peripheral nerve trajectory. CSPGs are dominant suppressors in scar tissue and exert inhibition via neuronal receptors including PTPσ. Previously, a small peptide memetic of the PTPσ wedge region named ISP (Intracellular Sigma Peptide) was generated, and its capabilities to target PTPσ and relieve CSPG inhibition were validated. Here, we demonstrate that after ventral root avulsion and immediate re-implantation, modulation of PTPσ by systemic delivery of ISP remarkably enhanced regeneration. ISP treatment reduced motoneuron death, increased the number of axons regenerating across scar tissue, rebuilt healthy neuromuscular junctions and enhanced motor functional recovery. Our study shows that modulation of PTPσ is a potential therapeutic strategy for root avulsion. PMID:26464223

  14. Mitragyna speciosa: hairy root culture for triterpenoid production and high yield of mitragynine by regenerated plants.

    PubMed

    Phongprueksapattana, Siriwan; Putalun, Waraporn; Keawpradub, Niwat; Wungsintaweekul, Juraithip

    2008-01-01

    Hairy root cultures of Mitragyna speciosa were established by infection of Agrobacterium rhizogenes ATCC 15834 and maintained in McCown woody plant medium (WPM) supplemented with 0.5 mg/1 naphthaleneacetic acid. The hairy roots were identified for the rooting genes loci of rolA and rolB by polymerase chain reaction. For studying the secondary metabolite production, the n-hexane extract of the hairy roots was prepared and the compounds were isolated by silica gel column chromatography, affording triterpenoids (ursolic acid and oleanolic acid) and phytosterols (beta-sitosterol and stigmasterol). The shoots from the hairy root cultures were regenerated and differentiated to the plantlets. For micropropagation, shoot multiplication was successfully induced from the axillary buds of the regenerated plantlets in WPM supplemented with 0.1 mg/l thidiazuron. The mitragynine contents of 5-month-old regenerated plants and in vitro plantlets (germinated from seeds) were determined using the TLC-densitometric method. The regenerated plants contained (14.25 +/- 0.25) mg/g dry wt mitragynine, whereas the in vitro plantlets contained (4.45 +/- 0.09) mg/g dry wt. PMID:19040109

  15. Overexpression of Arabidopsis phytochelatin synthase in tobacco plants enhances Cd(2+) tolerance and accumulation but not translocation to the shoot.

    PubMed

    Pomponi, Mirella; Censi, Vincenzo; Di Girolamo, Valentina; De Paolis, Angelo; di Toppi, Luigi Sanità; Aromolo, Rita; Costantino, Paolo; Cardarelli, Maura

    2006-01-01

    Phytochelatins (PCs) are metal binding peptides involved in heavy metal detoxification. To assess whether enhanced phytochelatin synthesis would increase heavy metal tolerance and accumulation in plants, we overexpressed the Arabidopsis phytochelatin synthase gene (AtPCS1) in the non-accumulator plant Nicotiana tabacum. Wild-type plants and plants harbouring the Agrobacterium rhizogenes rolB oncogene were transformed with a 35S AtPCS1 construct. Root cultures from rolB plants could be easily established and we demonstrated here that they represent a reliable system to study heavy metal tolerance. Cd(2+) tolerance in cultured rolB roots was increased as a result of overexpression of AtPCS1, and further enhanced when reduced glutathione (GSH, the substrate of PCS1) was added to the culture medium. Accordingly, HPLC analysis showed that total PC production in PCS1-overexpressing rolB roots was higher than in rolB roots in the presence of GSH. Overexpression of AtPCS1 in whole seedlings led to a twofold increase in Cd(2+) accumulation in the roots and shoots of both rolB and wild-type seedlings. Similarly, a significant increase in Cd(2+) accumulation linked to a higher production of PCs in both roots and shoots was observed in adult plants. However, the percentage of Cd(2+) translocated to the shoots of seedlings and adult overexpressing plants was unaffected. We conclude that the increase in Cd(2+) tolerance and accumulation of PCS1 overexpressing plants is directly related to the availability of GSH, while overexpression of phytochelatin synthase does not enhance long distance root-to-shoot Cd(2+) transport. PMID:16133212

  16. Plant microRNAs: key regulators of root architecture and biotic interactions.

    PubMed

    Couzigou, Jean-Malo; Combier, Jean-Philippe

    2016-10-01

    Contents 22 I. 22 II. 24 III. 25 IV. 27 V. 29 VI. 10 31 References 32 SUMMARY: Plants have evolved a remarkable faculty of adaptation to deal with various and changing environmental conditions. In this context, the roots have taken over nutritional aspects and the root system architecture can be modulated in response to nutrient availability or biotic interactions with soil microorganisms. This adaptability requires a fine tuning of gene expression. Indeed, root specification and development are highly complex processes requiring gene regulatory networks involved in hormonal regulations and cell identity. Among the different molecular partners governing root development, microRNAs (miRNAs) are key players for the fast regulation of gene expression. miRNAs are small RNAs involved in most developmental processes and are required for the normal growth of organisms, by the negative regulation of key genes, such as transcription factors and hormone receptors. Here, we review the known roles of miRNAs in root specification and development, from the embryonic roots to the establishment of root symbioses, highlighting the major roles of miRNAs in these processes. PMID:27292927

  17. Influence of plant roots on electrical resistivity measurements of cultivated soil columns

    NASA Astrophysics Data System (ADS)

    Maloteau, Sophie; Blanchy, Guillaume; Javaux, Mathieu; Garré, Sarah

    2016-04-01

    Electrical resistivity methods have been widely used for the last 40 years in many fields: groundwater investigation, soil and water pollution, engineering application for subsurface surveys, etc. Many factors can influence the electrical resistivity of a media, and thus influence the ERT measurements. Among those factors, it is known that plant roots affect bulk electrical resistivity. However, this impact is not yet well understood. The goals of this experiment are to quantify the effect of plant roots on electrical resistivity of the soil subsurface and to map a plant roots system in space and time with ERT technique in a soil column. For this research, it is assumed that roots system affect the electrical properties of the rhizosphere. Indeed the root activity (by transporting ions, releasing exudates, changing the soil structure,…) will modify the rhizosphere electrical conductivity (Lobet G. et al, 2013). This experiment is included in a bigger research project about the influence of roots system on geophysics measurements. Measurements are made on cylinders of 45 cm high and a diameter of 20 cm, filled with saturated loam on which seeds of Brachypodium distachyon (L.) Beauv. are sowed. Columns are equipped with electrodes, TDR probes and temperature sensors. Experiments are conducted at Gembloux Agro-Bio Tech, in a growing chamber with controlled conditions: temperature of the air is fixed to 20° C, photoperiod is equal to 14 hours, photosynthetically active radiation is equal to 200 μmol m‑2s‑1, and air relative humidity is fixed to 80 %. Columns are fully saturated the first day of the measurements duration then no more irrigation is done till the end of the experiment. The poster will report the first results analysis of the electrical resistivity distribution in the soil columns through space and time. These results will be discussed according to the plant development and other controlled factors. Water content of the soil will also be detailed

  18. Crop systems and plant roots can modify the soil water holding capacity

    NASA Astrophysics Data System (ADS)

    Doussan, Claude; Cousin, Isabelle; Berard, Annette; Chabbi, Abad; Legendre, Laurent; Czarnes, Sonia; Toussaint, Bruce; Ruy, Stéphane

    2015-04-01

    At the interface between atmosphere and deep sub-soil, the root zone plays a major role in regulating the flow of water between major compartments: groundwater / surface / atmosphere (drainage, runoff, evapotranspiration). This role of soil as regulator/control of water fluxes, but also as a supporting medium to plant growth, is strongly dependent on the hydric properties of the soil. In turn, the plant roots growing in the soil can change its structure; both in the plow layer and in the deeper horizons and, therefore, could change the soil properties, particularly hydric properties. Such root-related alteration of soil properties can be linked to direct effect of roots such as soil perforation during growth, aggregation of soil particles or indirect effects such as the release of exudates by roots that could modify the properties of water or of soil particles. On an another hand, the rhizosphere, the zone around roots influenced by the activity of root and associated microorganisms, could have a high influence on hydric properties, particularly the water retention. To test if crops and plant roots rhizosphere may have a significant effect on water retention, we conducted various experiment from laboratory to field scales. In the lab, we tested different soil and species for rhizospheric effect on soil water retention. Variation in available water content (AWC) between bulk and rhizospheric soil varied from non-significant to a significant increase (to about 16% increase) depending on plant species and soil type. In the field, the alteration of water retention by root systems was tested in different pedological settings for a Maize crop inoculated or not with the bacteria Azospirillum spp., known to alter root structure, growth and morphology. Again, a range of variation in AWC was evidenced, with significant increase (~30%) in some soil types, but more linked to innoculated/non-innoculated plants rather than to a difference between rhizospheric and bulk soil

  19. A below-ground herbivore shapes root defensive chemistry in natural plant populations.

    PubMed

    Huber, Meret; Bont, Zoe; Fricke, Julia; Brillatz, Théo; Aziz, Zohra; Gershenzon, Jonathan; Erb, Matthias

    2016-03-30

    Plants display extensive intraspecific variation in secondary metabolites. However, the selective forces shaping this diversity remain often unknown, especially below ground. Using Taraxacum officinale and its major native insect root herbivore Melolontha melolontha, we tested whether below-ground herbivores drive intraspecific variation in root secondary metabolites. We found that high M. melolontha infestation levels over recent decades are associated with high concentrations of major root latex secondary metabolites across 21 central European T. officinale field populations. By cultivating offspring of these populations, we show that both heritable variation and phenotypic plasticity contribute to the observed differences. Furthermore, we demonstrate that the production of the sesquiterpene lactone taraxinic acid β-D-glucopyranosyl ester (TA-G) is costly in the absence, but beneficial in the presence of M. melolontha, resulting in divergent selection of TA-G. Our results highlight the role of soil-dwelling insects for the evolution of plant defences in nature. PMID:27009228

  20. Effects of root-zone acidity on utilization of nitrate and ammonium in tobacco plants

    NASA Technical Reports Server (NTRS)

    Henry, L. T.; Raper, C. D. Jr; Raper CD, J. r. (Principal Investigator)

    1989-01-01

    Tobacco (Nicotiana tabacum L., cv. 'Coker 319') plants were grown for 28 days in flowing nutrient culture containing either 1.0 mM NO3- or 1.0 mM NH4+ as the nitrogen source in a complete nutrient solution. Acidities of the solutions were controlled at pH 6.0 or 4.0 for each nitrogen source. Plants were sampled at intervals of 6 to 8 days for determination of dry matter and nitrogen accumulation. Specific rates of NO3- or NH4+ uptake (rate of uptake per unit root mass) were calculated from these data. Net photosynthetic rates per unit leaf area were measured on attached leaves by infrared gas analysis. When NO3- [correction of NO-] was the sole nitrogen source, root growth and nitrogen uptake rate were unaffected by pH of the solution, and photosynthetic activity of leaves and accumulation of dry matter and nitrogen in the whole plant were similar. When NH4+ was the nitrogen source, photosynthetic rate of leaves and accumulation of dry matter and nitrogen in the whole plant were not statistically different from NO3(-) -fed plants when acidity of the solution was controlled at pH 6.0. When acidity for NH4(+) -fed plants was increased to pH 4.0, however, specific rate of NH4+ uptake decreased by about 50% within the first 6 days of treatment. The effect of acidity on root function was associated with a decreased rate of accumulation of nitrogen in shoots that was accompanied by a rapid cessation of leaf development between days 6 and 13. The decline in leaf growth rate of NH4(+) -fed plants at pH 4.0 was followed by reductions in photosynthetic rate per unit leaf area. These responses of NH4(+) -fed plants to increased root-zone acidity are characteristic of the sequence of responses that occur during onset of nitrogen stress.

  1. Spatial Regulation of Root Growth: Placing the Plant TOR Pathway in a Developmental Perspective.

    PubMed

    Barrada, Adam; Montané, Marie-Hélène; Robaglia, Christophe; Menand, Benoît

    2015-01-01

    Plant cells contain specialized structures, such as a cell wall and a large vacuole, which play a major role in cell growth. Roots follow an organized pattern of development, making them the organs of choice for studying the spatio-temporal regulation of cell proliferation and growth in plants. During root growth, cells originate from the initials surrounding the quiescent center, proliferate in the division zone of the meristem, and then increase in length in the elongation zone, reaching their final size and differentiation stage in the mature zone. Phytohormones, especially auxins and cytokinins, control the dynamic balance between cell division and differentiation and therefore organ size. Plant growth is also regulated by metabolites and nutrients, such as the sugars produced by photosynthesis or nitrate assimilated from the soil. Recent literature has shown that the conserved eukaryotic TOR (target of rapamycin) kinase pathway plays an important role in orchestrating plant growth. We will summarize how the regulation of cell proliferation and cell expansion by phytohormones are at the heart of root growth and then discuss recent data indicating that the TOR pathway integrates hormonal and nutritive signals to orchestrate root growth. PMID:26295391

  2. Spatial Regulation of Root Growth: Placing the Plant TOR Pathway in a Developmental Perspective

    PubMed Central

    Barrada, Adam; Montané, Marie-Hélène; Robaglia, Christophe; Menand, Benoît

    2015-01-01

    Plant cells contain specialized structures, such as a cell wall and a large vacuole, which play a major role in cell growth. Roots follow an organized pattern of development, making them the organs of choice for studying the spatio-temporal regulation of cell proliferation and growth in plants. During root growth, cells originate from the initials surrounding the quiescent center, proliferate in the division zone of the meristem, and then increase in length in the elongation zone, reaching their final size and differentiation stage in the mature zone. Phytohormones, especially auxins and cytokinins, control the dynamic balance between cell division and differentiation and therefore organ size. Plant growth is also regulated by metabolites and nutrients, such as the sugars produced by photosynthesis or nitrate assimilated from the soil. Recent literature has shown that the conserved eukaryotic TOR (target of rapamycin) kinase pathway plays an important role in orchestrating plant growth. We will summarize how the regulation of cell proliferation and cell expansion by phytohormones are at the heart of root growth and then discuss recent data indicating that the TOR pathway integrates hormonal and nutritive signals to orchestrate root growth. PMID:26295391

  3. Direct and indirect plant defenses are not suppressed by endosymbionts of a specialist root herbivore

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Insect endosymbionts influence many important metabolic and developmental processes of their host. It has been speculated that they may also help to manipulate and suppress plant defenses to the benefit of herbivores. Recently, endosymbionts of the root herbivore Diabrotica virgifera virgifera have ...

  4. SIMULATION OF NITROGEN MOVEMENT, TRANSFORMATION, AND UPTAKE IN PLANT ROOT ZONE

    EPA Science Inventory

    A detailed research model and a conceptual management model were developed to describe the fate of nitrogen in the plant root zone. Processes considered in both models were one-dimensional transport of water and water-soluble N-species as a result of irrigation/rainfall events, e...

  5. Soil bioturbation by earthworms and plant roots- mechanical and energetic considerations

    NASA Astrophysics Data System (ADS)

    Ruiz, S.; Or, D.; Schymanski, S. J.

    2014-12-01

    Soil structure is a key factor shaping hydrological and ecological functions including water storage, deep recharge and plant growth. Compaction adversely impacts soil ecosystem services over extended periods (years to decades) until structure and functionality are restored. An important class of soil structural restoration processes are related to biomechanical activity associated with borrowing of earthworms and root proliferation in impacted soils. This study employs a new biomechanical model to estimate stresses required for earthworm and plant root bioturbation under different conditions and the mechanical energy required. We consider steady state plastic cavity expansion to determine burrowing pressures of earthworms and plant roots as linked with models for cone penetration required for initial burrowing into soil volumes. We use earthworm physical and ecological parameters (e.g., population density, burrowing rate, and burrowing behavior) to convert mechanical deformation to estimation of energy and soil organic carbon (energy source for earthworms). Results illustrate a reduction in strain energy with increasing water content and trade-offs between pressure and energy investment for various root and earthworm geometries and soil hydration. The study provides a quantitative framework for estimating energy costs of bioturbation in terms of soil organic carbon or plant assimilates and delineates mechanical and hydration conditions that promote or constrain such activities.

  6. Soil Penetration Rates by Earthworms and Plant Roots- Mechanical and Energetic Considerations

    NASA Astrophysics Data System (ADS)

    Ruiz, Siul; Schymanski, Stan; Or, Dani

    2016-04-01

    We analyze the implications of different soil burrowing rates by earthworms and growing plant roots using mechanical models that consider soil rheological properties. We estimate the energetic requirements for soil elasto-viscoplastic displacement at different rates for similar burrows and water contents. In the core of the mechanical model is a transient cavity expansion into viscoplastic wet soil that mimic an earthworm or root tip cone-like penetration and subsequent cavity expansion due to pressurized earthworm hydrostatic skeleton or root radial growth. Soil matrix viscoplatic considerations enable separation of the respective energetic requirements for earthworms penetrating at 2 μm/s relative to plant roots growing at 0.2 μm/s . Typical mechanical and viscous parameters are obtained inversely for soils under different fixed water contents utilizing custom miniaturized cone penetrometers at different fixed penetration rates (1 to 1000 μm/s). Experimental results determine critical water contents where soil exhibits pronounced viscoplatic behavior (close to saturation), bellow which the soil strength limits earthworms activity and fracture propagation by expanding plant roots becomes the favorable mechanical mode. The soil mechanical parameters in conjunction with earthworm and plant root physiological pressure limitations (200 kPa and 2000 kPa respectively) enable delineation of the role of soil saturation in regulating biotic penetration rates for different soil types under different moisture contents. Furthermore, this study provides a quantitative framework for estimating rates of energy expenditure for soil penetration, which allowed us to determine maximum earthworm population densities considering soil mechanical properties and the energy stored in soil organic matter.

  7. Enhanced root and shoot growth of wheat (Triticum aestivum L.) by Trichoderma harzianum from Turkey.

    PubMed

    Kucuk, Cigdem

    2014-01-01

    It is well known that Trichoderma species can be used as biocontrol and plant growth promote agent. In this study, Trichoderma harzianum isolates were evaluated for their growth promotion effects on wheat in greenhouse experiments. Two isolates of T. harzianum were used. The experimental design was a randomized complete block with three replications. Seeds were inoculated with conidial suspensions of each isolate. Wheat plants grown in steriled soil in pots. T. harzianum T8 and T15 isolates increased wheat length, root dry weight and shoot dry weight according to untreated control. Turkish isolates T8 and T15 did not produce damage in seeds nor in plants. PMID:24783790

  8. The role of the cytoskeleton in the gravisensing and graviresponse mechanisms of plant roots

    NASA Astrophysics Data System (ADS)

    Blancaflor, E.; Hou, G.; Mohamalawari, D.

    The cytoskeleton has been proposed to be a major player in the process of gravitropism. A major approach to determine the role of the cytoskeleton in gravitropism has been to use cytoskeletal disrupting drugs. Several investigators have reported that actin or microtubule inhibitors do not prevent root gravitropism therefore they concluded that the cytoskeleton is not involved in this process. However, some recent studies indicate that actin inhibitors promote gravitropism in both roots and shoots. To further investigate the significance of these observations, we studied the effect of various cytoskeletal inhibitors on roots grown on a clinostat in an effort to analyze other p rameters used to assay for gravisensitivity (e.g.a presentation time). Latrunculin B (LB) an actin-disrupting drug enhanced the gravisensitivity of a variety of roots as evident from the comparison of presentation times in LB-treated versus untreated roots . The microtubule inhibitor oryzalin did not have any significant effect on gravitropic sensitivity. Interestingly, roots treated with LB consistently showed hyper-gravitropic responses. Roots gravistimulated for 5-10 min and then rotated on a clinostat displayed extensive curvature. Application of LB specifically to the cap or elongation zone (EZ) of maize roots caused the disruption of the actin cytoskeleton, and such disruption was confined to regions of localized LB application. Only roots with disrupted actin in the cap displayed enhanced gravitropic sensitivity further emphasizing the importance of the root cap actin cytoskeleton in mediating gravitropism. The myosin inhibitor 2,3-butanedione monoxime (BDM) did not alter the sensitivity of roots to gravity suggesting that the hypergravitropic responses resulting from the disruption of actin filaments may not involve myosin motors. The increased sensitivity of roots to gravity after disruption of actin filaments suggests that an intact actin cytoskeleton in the cap is involved in

  9. Scaleable Nitrate Microsensors in the Form of a Plant Root

    NASA Astrophysics Data System (ADS)

    Harmon, T. C.; Jurisch, N. L.; Davidson, M. J.; Haux, J. E.

    2004-12-01

    This work describes the development of flexible, miniature and inexpensive nitrate sensors by electropolymerizing pyrrole onto carbon fiber substrates, using nitrate as a dopant. Carbon microfibers were found to be an excellent substitute to expensive conductive materials, such as glassy carbon or platinum. The electrodes with a 3-5 micron layer of NO3 -doped polypyrrole (PPy) exhibited a promising lifetime (at least 2 month without changes in sensitivity and linear response), fast response times (seconds), and sensitivity competitive to commercial nitrate ISE. Nernstian sensor response slopes of 54 to 58 mV/(decade concentration) for single filament have been observed, with a linear response to nitrate concentrations spanning three orders of magnitude (0.1 - 10-4 M or 6200 - 6.2 ppm of NO3-), and a detection limit of (3 ± 1) x 10-5 M (1.25-2.5 ppm). An advantage of using the carbon fibers as a substrate for pyrrole polymerization process is that these fibers are relatively easy to manipulate, lending themselves to root-like electrode designs which may be ideal for observing the water chemistry of soil moisture. Using prototypical PPy-coated microfibers, we have been able to directly measure nitrate concentrations in residual soil water contents as low as 8 percent by weight for a medium sand. Results for model soils and field samples are presented in which direct measurements with the microsensors compare reasonably well with a more conventional analytical method entailing soil extraction and analysis by the Griess-Romijn method.

  10. [Induction and in vitro culture of hairy roots of Dianthus caryophyllus and its plant regeneration].

    PubMed

    Shi, Heping; Zhu, Yuanfeng; Wang, Bei; Sun, Jiangbing; Huang, Shengqin

    2014-11-01

    To use Agrobacterium rhizogenes-induced hairy roots to create new germplasm of Dianthus caryophyllus, we transformed D. caryophyllus with A. rhizogenes by leaf disc for plant regeneration from hairy roots. The white hairy roots could be induced from the basal surface of leaf explants of D. caryophyllus 12 days after inoculation with A. rhizogenes ATCC15834. The percentage of the rooting leaf explants was about 90% 21 days after inoculation. The hairy roots could grow rapidly and autonomously in liquid or solid phytohormone-free MS medium. The transformation was confirmed by PCR amplification of rol gene of Ri plasmid and silica gel thin-layer chromatography of opines from D. caryophyllus hairy roots. Hairy roots could form light green callus after cultured on MS+6-BA 1.0-3.0 mg/L + NAA 0.1-0.2 mg/L for 15 days. The optimum medium for adventitious shoots formation was MS + 6-BA 2.0 mg/L + NAA 0.02 mg/L, where the rate of adventitious shoot induction was 100% after cultured for 6 weeks. The mean number of adventitious shoot per callus was 30-40. The adventitious shoots can form roots when cultured on phytohormone-free 1/2 MS or 1/2 MS +0.5 mg/L NAA for 10 days. When the rooted plantlets transplanted in the substrate mixed with perlite sand and peat (volume ratio of 1:2), the survival rate was above 95%. PMID:25985525

  11. Colonization of root cells and plant growth promotion by Piriformospora indica occurs independently of plant common symbiosis genes

    PubMed Central

    Banhara, Aline; Ding, Yi; Kühner, Regina; Zuccaro, Alga; Parniske, Martin

    2015-01-01

    Arbuscular mycorrhiza (AM) fungi (Glomeromycota) form symbiosis with and deliver nutrients via the roots of most angiosperms. AM fungal hyphae are taken up by living root epidermal cells, a program which relies on a set of plant common symbiosis genes (CSGs). Plant root epidermal cells are also infected by the plant growth-promoting fungus Piriformospora indica (Basidiomycota), raising the question whether this interaction relies on the AM-related CSGs. Here we show that intracellular colonization of root cells and intracellular sporulation by P. indica occurred in CSG mutants of the legume Lotus japonicus and in Arabidopsis thaliana, which belongs to the Brassicaceae, a family that has lost the ability to form AM as well as a core set of CSGs. A. thaliana mutants of homologs of CSGs (HCSGs) interacted with P. indica similar to the wild-type. Moreover, increased biomass of A. thaliana evoked by P. indica was unaltered in HCSG mutants. We conclude that colonization and growth promotion by P. indica are independent of the CSGs and that AM fungi and P. indica exploit different host pathways for infection. PMID:26441999

  12. Some effects of high- gradient magnetic field on tropism of roots of higher plants

    NASA Astrophysics Data System (ADS)

    Kondrachuk, A.; Belyavskaya, N.

    The perception of gravity in living organisms is mostly based on the response of the gravisensing system to displacement of some specific mass caused by gravitational force. According to the starch-statolith hypothesis the amyloplasts play the role of specific mass in gravisensing cells of higher plants. Kuznetsov & Hasenstein (1996) have demonstrated that the high-gradient magnetic field (HGMF) exerts a directional ponderomotive force on diamagnetic substances, in particular, statoliths. This effect of the HGMF causes root response similar to that produced by the change in gravity vector. Their studies supported the starch-statolith hypothesis and showed that ponderomotive force can be used to modify force acting on statoliths by manipulating statolith locations within gravisensing cells. We have designed the HGMF facility that allows for generating the HGMF and analyzing its effects on higher plants' roots. It records by videosystem and measures with the help of image analysis software the parameters of kinetics of root bending under both the HGMF action and gravistimulation. Two species of plants (pea and cress) have been examined. The main results of the work are the following: 1) The magnetotropic effect of HGMF on root growth was found for both species. 2) The critical value of ponderomotive force that caused the magnetotropic effect was estimated by modeling the magnetic field spatial distribution in the region of root apex. 3) The electron-microscopic analysis of statocytes after the HGMF treatment was carried out. The displacement of amyloplasts in root statocytes of two species of plants in HGMF was firstly demonstrated at the ultrastructural level. 4) Spatial distribution of exogenous proton fluxes (pH) along the roots was studied. The changes in pH distribution along curvature zone and apices of roots were revealed in the HGMF. It is known that application of HGMFs or strong uniform magnetic fields may influence ion transport due to Ampere force. It

  13. Plant functional traits and phylogenetic relatedness explain variation in associations with root fungal endophytes in an extreme arid environment

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Since root endophytes may ameliorate drought stress, understanding which plants associate with endophytes is important, especially in arid ecosystems. Here we characterized the root endophytes of 42 plants from an arid region of Argentina. We related colonization by arbuscular mycorrhizal fungi (AMF...

  14. Genotype Response of Soybean (Glycine max) Whole Plants and Hairy Roots to Fusarium solani f. sp. glycines Infection

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Fusarium solani f. sp. Glycines, a soilborne fungus, infects soybean roots and causes sudden death syndrome. The response of 13 soybean genotypes to the pathogen infection was tested with potted greenhouse grown plants and with cultured hairy roots. The taproots of all genotypes grown plants measure...

  15. Enhancement of Na+ Uptake Currents, Time-Dependent Inward-Rectifying K+ Channel Currents, and K+ Channel Transcripts by K+ Starvation in Wheat Root Cells1

    PubMed Central

    Buschmann, Peter H.; Vaidyanathan, Rama; Gassmann, Walter; Schroeder, Julian I.

    2000-01-01

    Excessive low-affinity Na+ uptake is toxic to the growth of glycophytic plants. Recently, several reports have suggested that the interaction between K+ and Na+ uptake might represent a key factor in determining the Na+ tolerance of plants. We investigated the effects of K+ starvation on Na+ and K+ uptake mechanisms in the plasma membrane of wheat (Triticum aestivum L.) root cortex cells using the patch-clamp technique. Unexpectedly, K+ starvation of wheat seedlings was found to enhance the magnitude and frequency of occurrence of time-dependent inward-rectifying K+ channel currents (IK+in). We examined whether the transcription of a wheat root K+in channel gene is induced by K+ starvation. A cDNA coding for a wheat root K+ channel homolog, TaAKT1 (accession no. AF207745), was isolated. TaAKT1 mRNA levels were up-regulated in roots in response to withdrawal of K+ from the growth medium. Furthermore, K+ starvation caused an enhancement of instantaneous Na+ currents (INa+). Electrophysiological analyses suggested that IK+in and INa+ are not mediated by the same transport protein based on: (a) different activation curves, (b) different time dependencies, (c) different sensitivities to external Ca2+, and (d) different cation selectivities. These data implicate a role for INa+ in Na+ uptake and stress during K+ starvation, and indicate that K+in channels may contribute to K+-starvation-induced K+ uptake in wheat roots. PMID:10759535

  16. Plant systemic induced responses mediate interactions between root parasitic nematodes and aboveground herbivorous insects

    PubMed Central

    Wondafrash, Mesfin; Van Dam, Nicole M.; Tytgat, Tom O. G.

    2013-01-01

    Insects and nematodes are the most diverse and abundant groups of multicellular animals feeding on plants on either side of the soil–air interface. Several herbivore-induced responses are systemic, and hence can influence the preference and performance of organisms in other plant organs. Recent studies show that plants mediate interactions between belowground plant parasitic nematodes (PPNs) and aboveground herbivorous insects. Based on the knowledge of plant responses to pathogens, we review the emerging insights on plant systemic responses against root-feeding nematodes and shoot-feeding insects. We discuss the potential mechanisms of plant-mediated indirect interactions between both groups of organisms and point to gaps in our knowledge. Root-feeding nematodes can positively or negatively affect shoot herbivorous insects, and vice versa. The outcomes of the interactions between these spatially separated herbivore communities appear to be influenced by the feeding strategy of the nematodes and the insects, as well as by host plant susceptibility to both herbivores. The potential mechanisms for these interactions include systemic induced plant defense, interference with the translocation and dynamics of locally induced secondary metabolites, and reallocation of plant nutritional reserves. During evolution, PPNs as well as herbivorous insects have acquired effectors that modify plant defense responses and resource allocation patterns to their advantage. However, it is also known that plants under herbivore attack change the allocation of their resources, e.g., for compensatory growth responses, which may affect the performance of other organisms feeding on the plant. Studying the chemical and molecular basis of these interactions will reveal the molecular mechanisms that are involved. Moreover, it will lead to a better understanding of the ecological relevance of aboveground–belowground interactions, as well as support the development of sustainable pest

  17. Plant systemic induced responses mediate interactions between root parasitic nematodes and aboveground herbivorous insects.

    PubMed

    Wondafrash, Mesfin; Van Dam, Nicole M; Tytgat, Tom O G

    2013-01-01

    Insects and nematodes are the most diverse and abundant groups of multicellular animals feeding on plants on either side of the soil-air interface. Several herbivore-induced responses are systemic, and hence can influence the preference and performance of organisms in other plant organs. Recent studies show that plants mediate interactions between belowground plant parasitic nematodes (PPNs) and aboveground herbivorous insects. Based on the knowledge of plant responses to pathogens, we review the emerging insights on plant systemic responses against root-feeding nematodes and shoot-feeding insects. We discuss the potential mechanisms of plant-mediated indirect interactions between both groups of organisms and point to gaps in our knowledge. Root-feeding nematodes can positively or negatively affect shoot herbivorous insects, and vice versa. The outcomes of the interactions between these spatially separated herbivore communities appear to be influenced by the feeding strategy of the nematodes and the insects, as well as by host plant susceptibility to both herbivores. The potential mechanisms for these interactions include systemic induced plant defense, interference with the translocation and dynamics of locally induced secondary metabolites, and reallocation of plant nutritional reserves. During evolution, PPNs as well as herbivorous insects have acquired effectors that modify plant defense responses and resource allocation patterns to their advantage. However, it is also known that plants under herbivore attack change the allocation of their resources, e.g., for compensatory growth responses, which may affect the performance of other organisms feeding on the plant. Studying the chemical and molecular basis of these interactions will reveal the molecular mechanisms that are involved. Moreover, it will lead to a better understanding of the ecological relevance of aboveground-belowground interactions, as well as support the development of sustainable pest management

  18. A Novel Growing Device Inspired by Plant Root Soil Penetration Behaviors

    PubMed Central

    Sadeghi, Ali; Tonazzini, Alice; Popova, Liyana; Mazzolai, Barbara

    2014-01-01

    Moving in an unstructured environment such as soil requires approaches that are constrained by the physics of this complex medium and can ensure energy efficiency and minimize friction while exploring and searching. Among living organisms, plants are the most efficient at soil exploration, and their roots show remarkable abilities that can be exploited in artificial systems. Energy efficiency and friction reduction are assured by a growth process wherein new cells are added at the root apex by mitosis while mature cells of the root remain stationary and in contact with the soil. We propose a new concept of root-like growing robots that is inspired by these plant root features. The device penetrates soil and develops its own structure using an additive layering technique: each layer of new material is deposited adjacent to the tip of the device. This deposition produces both a motive force at the tip and a hollow tubular structure that extends to the surface of the soil and is strongly anchored to the soil. The addition of material at the tip area facilitates soil penetration by omitting peripheral friction and thus decreasing the energy consumption down to 70% comparing with penetration by pushing into the soil from the base of the penetration system. The tubular structure provides a path for delivering materials and energy to the tip of the system and for collecting information for exploratory tasks. PMID:24587244

  19. A reliable and efficient protocol for inducing genetically transformed roots in medicinal plant Nepeta pogonosperma.

    PubMed

    Valimehr, Sepideh; Sanjarian, Forough; Sohi, Haleh Hashemi; Sharafi, Ali; Sabouni, Farzaneh

    2014-07-01

    Nepeta pogonosperma is an important medicinal plant with anti-inflammatory effects. An efficient and reliable transformation system for this plant was developed through optimization of several factors which affected the rate of Agrobacterium rhizogenes mediated transformation. Five bacterial strains, A4, ATCC15834, LBA9402, MSU440 and A13, two explant types, leaves and stems, and several co-cultivation media were examined. The maximum rate of hairy root induction was obtained from stem explants using MSU440 and ATCC15834 bacterial strains. A drastic increase in the frequency of transformation (91 %) was observed when MS medium lacking NH4NO3, KH2PO4, KNO3 and CaCl2. Hairy root lines were confirmed by polymerase chain reaction (PCR) using primers of the rolB gene. According to Southern blot analysis, one T-DNA copy was inserted into each of the hairy root lines. In the present study, transgenic hairy roots have been obtained trough genetic transformation by A. rhizogenes harbouring two plasmids, the Ri plasmid and pBI121 binary vector harbouring gus reporter gene. Expression of the gus gene in transgenic hairy root was confirmed by histochemical GUS assay. PMID:25049462

  20. Microscopic processes ruling the bioavailability of Zn to roots of Euphorbia pithyusa L. pioneer plant.

    PubMed

    Medas, Daniela; De Giudici, Giovanni; Casu, Maria Antonietta; Musu, Elodia; Gianoncelli, Alessandra; Iadecola, Antonella; Meneghini, Carlo; Tamburini, Elena; Sprocati, Anna Rosa; Turnau, Katarzyna; Lattanzi, Pierfranco

    2015-02-01

    Euphorbia pithyusa L. was used in a plant growth-promoting assisted field trial experiment. To unravel the microscopic processes at the interface, thin slices of E. pithyusa roots were investigated by micro-X-ray fluorescence mapping. Roots and rhizosphere materials were examined by X-ray absorption spectroscopy at the Zn K-edge, X-ray diffraction, and scanning electron microscopy. Results indicate some features common to all the investigated samples. (i) In the rhizosphere of E. pithyusa, Zn was found to exist in different phases. (ii) Si and Al are mainly concentrated in a rim at the epidermis of the roots. (iii) Zn is mostly stored in root epidermis and does not appear to be coordinated to organic molecules but mainly occurs in mineral phases such as Zn silicates. We interpreted that roots of E. pithyusa significantly promote mineral evolution in the rhizosphere. Concomitantly, the plant uses Si and Al extracted by soil minerals to build a biomineralization rim, which can capture Zn. This Zn silicate biomineralization has relevant implications for phytoremediation techniques and for further biotechnology development, which can be better designed and developed after specific knowledge of molecular processes ruling mineral evolution and biomineralization processes has been gained. PMID:25568986

  1. Growth, Root Formation, and Nutrient Value of Triticale Plants Fertilized with Biosolids

    PubMed Central

    Rauw, Wendy Mercedes; Teglas, Michael Bela; Chandra, Sudeep; Forister, Matthew Lewis

    2012-01-01

    Biosolids are utilized as nutrient rich fertilizer. Little material is available on benefits to forage crops resulting from fertilization with biosolids. This paper aimed to compare the effects of fertilization with biosolids versus commercial nitrogen fertilizer on growth, root formation, and nutrient value of triticale plants in a greenhouse experiment. Per treatment, five pots were seeded with five triticale seeds each. Treatments included a nonfertilized control, fertilization with 100, 200, 300, 400, and 500 ml biosolids per pot, and fertilization with a commercial nitrogen fertilizer at the recommended application rate and at double that rate. Biomass production, root length, root diameter, nitrogen, phosphorus, and potassium concentration were analyzed at harvest. Fertilization with biosolids increased triticale production (P < 0.001); production was similar for the 100 to 400 mL treatments. Root length, nitrogen, and phosphorus concentration increased, and potassium concentration decreased linearly with application rate. At the recommended rate, biomass production was similar between fertilization with biosolids and commercial fertilizer. However, plants fertilized with commercial fertilizer had considerably longer roots (P < 0.001), higher nitrogen concentration (P < 0.05), and lower potassium concentration (P < 0.01) than those fertilized with biosolids. Our results indicate that at the recommended application rate, biomass production was similar between fertilization with biosolids and with commercial nitrogen fertilizer, indicating the value of biosolids fertilization as a potential alternative. PMID:22593686

  2. A late embryogenesis abundant protein HVA1 regulated by an inducible promoter enhances root growth and abiotic stress tolerance in rice without yield penalty.

    PubMed

    Chen, Yi-Shih; Lo, Shuen-Fang; Sun, Peng-Kai; Lu, Chung-An; Ho, Tuan-Hua D; Yu, Su-May

    2015-01-01

    Regulation of root architecture is essential for maintaining plant growth under adverse environment. A synthetic abscisic acid (ABA)/stress-inducible promoter was designed to control the expression of a late embryogenesis abundant protein (HVA1) in transgenic rice. The background of HVA1 is low but highly inducible by ABA, salt, dehydration and cold. HVA1 was highly accumulated in root apical meristem (RAM) and lateral root primordia (LRP) after ABA/stress treatments, leading to enhanced root system expansion. Water-use efficiency (WUE) and biomass also increased in transgenic rice, likely due to the maintenance of normal cell functions and metabolic activities conferred by HVA1 which is capable of stabilizing proteins, under osmotic stress. HVA1 promotes lateral root (LR) initiation, elongation and emergence and primary root (PR) elongation via an auxin-dependent process, particularly by intensifying asymmetrical accumulation of auxin in LRP founder cells and RAM, even under ABA/stress-suppressive conditions. We demonstrate a successful application of an inducible promoter in regulating the spatial and temporal expression of HVA1 for improving root architecture and multiple stress tolerance without yield penalty. PMID:25200982

  3. Wild plant species growing closely connected in a subalpine meadow host distinct root-associated bacterial communities

    PubMed Central

    Aleklett, Kristin; Leff, Jonathan W.; Fierer, Noah

    2015-01-01

    Plant roots are known to harbor large and diverse communities of bacteria. It has been suggested that plant identity can structure these root-associated communities, but few studies have specifically assessed how the composition of root microbiota varies within and between plant species growing under natural conditions. We assessed the community composition of endophytic and epiphytic bacteria through high throughput sequencing using 16S rDNA derived from root tissues collected from a population of a wild, clonal plant (Orange hawkweed–Pilosella aurantiaca) as well as two neighboring plant species (Oxeye daisy–Leucanthemum vulgare and Alsike clover–Trifolium hybridum). Our first goal was to determine if plant species growing in close proximity, under similar environmental conditions, still hosted unique root microbiota. Our results showed that plants of different species host distinct bacterial communities in their roots. In terms of community composition, Betaproteobacteria (especially the family Oxalobacteraceae) were found to dominate in the root microbiota of L. vulgare and T. hybridum samples, whereas the root microbiota of P. aurantiaca had a more heterogeneous distribution of bacterial abundances where Gammaproteobacteria and Acidobacteria occupied a larger portion of the community. We also explored the extent of individual variance within each plant species investigated, and found that in the plant species thought to have the least genetic variance among individuals (P. aurantiaca) still hosted just as diverse microbial communities. Whether all plant species host their own distinct root microbiota and plants more closely related to each other share more similar bacterial communities still remains to be fully explored, but among the plants examined in this experiment there was no trend that the two species belonging to the same family shared more similarities in terms of bacterial community composition. PMID:25755932

  4. Wild plant species growing closely connected in a subalpine meadow host distinct root-associated bacterial communities.

    PubMed

    Aleklett, Kristin; Leff, Jonathan W; Fierer, Noah; Hart, Miranda

    2015-01-01

    Plant roots are known to harbor large and diverse communities of bacteria. It has been suggested that plant identity can structure these root-associated communities, but few studies have specifically assessed how the composition of root microbiota varies within and between plant species growing under natural conditions. We assessed the community composition of endophytic and epiphytic bacteria through high throughput sequencing using 16S rDNA derived from root tissues collected from a population of a wild, clonal plant (Orange hawkweed-Pilosella aurantiaca) as well as two neighboring plant species (Oxeye daisy-Leucanthemum vulgare and Alsike clover-Trifolium hybridum). Our first goal was to determine if plant species growing in close proximity, under similar environmental conditions, still hosted unique root microbiota. Our results showed that plants of different species host distinct bacterial communities in their roots. In terms of community composition, Betaproteobacteria (especially the family Oxalobacteraceae) were found to dominate in the root microbiota of L. vulgare and T. hybridum samples, whereas the root microbiota of P. aurantiaca had a more heterogeneous distribution of bacterial abundances where Gammaproteobacteria and Acidobacteria occupied a larger portion of the community. We also explored the extent of individual variance within each plant species investigated, and found that in the plant species thought to have the least genetic variance among individuals (P. aurantiaca) still hosted just as diverse microbial communities. Whether all plant species host their own distinct root microbiota and plants more closely related to each other share more similar bacterial communities still remains to be fully explored, but among the plants examined in this experiment there was no trend that the two species belonging to the same family shared more similarities in terms of bacterial community composition. PMID:25755932

  5. Fine root tradeoffs between nitrogen concentration and xylem vessel traits preclude unified whole-plant resource strategies in Helianthus.

    PubMed

    Bowsher, Alan W; Mason, Chase M; Goolsby, Eric W; Donovan, Lisa A

    2016-02-01

    Recent work suggests variation in plant growth strategies is governed by a tradeoff in resource acquisition and use, ranging from a rapid resource acquisition strategy to a resource-conservative strategy. While evidence for this tradeoff has been found in leaves, knowledge of root trait strategies, and whether they reflect adaptive differentiation across environments, is limited. In the greenhouse, we investigated variation in fine root morphology (specific root length and tissue density), chemistry (nitrogen concentration and carbon:nitrogen), and anatomy (root cross-sectional traits) in populations of 26 Helianthus species and sister Phoebanthus tenuifolius. We also compared root trait variation in this study with leaf trait variation previously reported in a parallel study of these populations. Root traits varied widely and exhibited little phylogenetic signal, suggesting high evolutionary lability. Specific root length and root tissue density were weakly negatively correlated, but neither was associated with root nitrogen, providing little support for a single axis of root trait covariation. Correlations between traits measured in the greenhouse and native site characteristics were generally weak, suggesting a variety of equally viable root trait combinations exist within and across environments. However, high root nitrogen was associated with lower xylem vessel number and cross-sectional area, suggesting a tradeoff between nutrient investment and water transport capacity. This led to correlations between root and leaf traits that were not always consistent with an acquisition-conservation tradeoff at the whole-plant level. Given that roots must balance acquisition of water and nutrients with functions like anchorage, exudation, and microbial symbioses, the varied evidence for root trait covariation likely reflects the complexity of interacting selection pressures belowground. Similarly, the lack of evidence for a single acquisition-conservation tradeoff at the

  6. Concept for Sustained Plant Production on ISS Using VEGGIE Capillary Mat Rooting System

    NASA Technical Reports Server (NTRS)

    Stutte, Gary W.; Newsham, Gerard; Morrow, Robert M.; Wheeler, Raymond M.

    2011-01-01

    Plant growth in microgravity presents unique challenges associated with maintaining appropriate conditions for seed germination, seedling establishment, maturation and harvest. They include maintaining appropriate soil moisture content, nutrient balance, atmospheric mixing and containment. Sustained production imposes additional challenges of harvesting, replanting, and safety. The VEGGIE is a deployable (collapsible) plant growth chamber developed as part of a NASA SBIR Phase II by Orbitec, Madison, WI. The intent of VEGGIE is to provide a low-resource system to produce fresh vegetables for the crew on long duration missions. The VEGGIE uses and LED array for lighting, an expandable bellows for containment, and a capillary matting system for nutrient and water delivery. The project evaluated a number of approaches to achieve sustained production, and repeated plantings, using the capillary rooting system. A number of different root media, seed containment, and nutrient delivery systems were evaluated and effects on seed germination and growth were evaluated. A number of issues limiting sustained production, such as accumulation of nutrients, uniform water, elevated vapor pressure deficit, and media containment were identified. A concept using pre-planted rooting packs shown to effectively address a number of those issues and is a promising approach for future development as a planting system for microgravity conditions.

  7. Invasive clonal plant species have a greater root-foraging plasticity than non-invasive ones.

    PubMed

    Keser, Lidewij H; Dawson, Wayne; Song, Yao-Bin; Yu, Fei-Hai; Fischer, Markus; Dong, Ming; van Kleunen, Mark

    2014-03-01

    Clonality is frequently positively correlated with plant invasiveness, but which aspects of clonality make some clonal species more invasive than others is not known. Due to their spreading growth form, clonal plants are likely to experience spatial heterogeneity in nutrient availability. Plasticity in allocation of biomass to clonal growth organs and roots may allow these plants to forage for high-nutrient patches. We investigated whether this foraging response is stronger in species that have become invasive than in species that have not. We used six confamilial pairs of native European clonal plant species differing in invasion success in the USA. We grew all species in large pots under homogeneous or heterogeneous nutrient conditions in a greenhouse, and compared their nutrient-foraging response and performance. Neither invasive nor non-invasive species showed significant foraging responses to heterogeneity in clonal growth organ biomass or in aboveground biomass of clonal offspring. Invasive species had, however, a greater positive foraging response in terms of root and belowground biomass than non-invasive species. Invasive species also produced more total biomass. Our results suggest that the ability for strong root foraging is among the characteristics promoting invasiveness in clonal plants. PMID:24352844

  8. Degradation kinetics of chlorinated aliphatic hydrocarbons by methane oxidizers naturally-associated with wetland plant roots

    NASA Astrophysics Data System (ADS)

    Powell, C. L.; Goltz, M. N.; Agrawal, A.

    2014-12-01

    Chlorinated aliphatic hydrocarbons (CAHs) are common groundwater contaminants that can be removed from the environment by natural attenuation processes. CAH biodegradation can occur in wetland environments by reductive dechlorination as well as oxidation pathways. In particular, CAH oxidation may occur in vegetated wetlands, by microorganisms that are naturally associated with the roots of wetland plants. The main objective of this study was to evaluate the cometabolic degradation kinetics of the CAHs, cis-1,2-dichloroethene (cisDCE), trichloroethene (TCE), and 1,1,1-trichloroethane (1,1,1TCA), by methane-oxidizing bacteria associated with the roots of a typical wetland plant in soil-free system. Laboratory microcosms with washed live roots investigated aerobic, cometabolic degradation of CAHs by the root-associated methane-oxidizing bacteria at initial aqueous [CH4] ~ 1.9 mg L- 1, and initial aqueous [CAH] ~ 150 μg L- 1; cisDCE and TCE (in the presence of 1,1,1TCA) degraded significantly, with a removal efficiency of approximately 90% and 46%, respectively. 1,1,1TCA degradation was not observed in the presence of active methane oxidizers. The pseudo first-order degradation rate-constants of TCE and cisDCE were 0.12 ± 0.01 and 0.59 ± 0.07 d- 1, respectively, which are comparable to published values. However, their biomass-normalized degradation rate constants obtained in this study were significantly smaller than pure-culture studies, yet they were comparable to values reported for biofilm systems. The study suggests that CAH removal in wetland plant roots may be comparable to processes within biofilms. This has led us to speculate that the active biomass may be on the root surface as a biofilm. The cisDCE and TCE mass losses due to methane oxidizers in this study offer insight into the role of shallow, vegetated wetlands as an environmental sink for such xenobiotic compounds.

  9. Sensitivity of Bedding Plants to Southern Root-knot Nematode, Meloidogyne incognita Race 3.

    PubMed

    Walker, J T; Melin, J B; Davis, J

    1994-12-01

    Thirty-two cultivars of 10 commonly-grown bedding plants, representing eight families, were evaluated for their response to infection by the root-knot nematode, Meloidogyne incognita race 3, under greenhouse conditions. Four ageratum cultivars, two marigold, and two salvia cultivars were rated resistant after exposure for 8 weeks. Four begonia, four celosia, one dianthus, one verbena, one vinca, and three pansy cultivars were susceptible. Three salvia, one begonia, one gerber, one verbena, and three vinca cultivars were slightly susceptible with an average of plant. Nematodes, at two initial population densities, affected the dry weights of only a few cultivars. The diversity of annual bedding plant germplasm available may provide adequate sources of resistance to this race of root-knot nematode. PMID:19279964

  10. Root Endophyte Colletotrichum tofieldiae Confers Plant Fitness Benefits that Are Phosphate Status Dependent.

    PubMed

    Hiruma, Kei; Gerlach, Nina; Sacristán, Soledad; Nakano, Ryohei Thomas; Hacquard, Stéphane; Kracher, Barbara; Neumann, Ulla; Ramírez, Diana; Bucher, Marcel; O'Connell, Richard J; Schulze-Lefert, Paul

    2016-04-01

    A staggering diversity of endophytic fungi associate with healthy plants in nature, but it is usually unclear whether these represent stochastic encounters or provide host fitness benefits. Although most characterized species of the fungal genus Colletotrichum are destructive pathogens, we show here that C. tofieldiae (Ct) is an endemic endophyte in natural Arabidopsis thaliana populations in central Spain. Colonization by Ct initiates in roots but can also spread systemically into shoots. Ct transfers the macronutrient phosphorus to shoots, promotes plant growth, and increases fertility only under phosphorus-deficient conditions, a nutrient status that might have facilitated the transition from pathogenic to beneficial lifestyles. The host's phosphate starvation response (PSR) system controls Ct root colonization and is needed for plant growth promotion (PGP). PGP also requires PEN2-dependent indole glucosinolate metabolism, a component of innate immune responses, indicating a functional link between innate immunity and the PSR system during beneficial interactions with Ct. PMID:26997485

  11. Root Endophyte Colletotrichum tofieldiae Confers Plant Fitness Benefits that Are Phosphate Status Dependent

    PubMed Central

    Hiruma, Kei; Gerlach, Nina; Sacristán, Soledad; Nakano, Ryohei Thomas; Hacquard, Stéphane; Kracher, Barbara; Neumann, Ulla; Ramírez, Diana; Bucher, Marcel; O’Connell, Richard J.; Schulze-Lefert, Paul

    2016-01-01

    Summary A staggering diversity of endophytic fungi associate with healthy plants in nature, but it is usually unclear whether these represent stochastic encounters or provide host fitness benefits. Although most characterized species of the fungal genus Colletotrichum are destructive pathogens, we show here that C. tofieldiae (Ct) is an endemic endophyte in natural Arabidopsis thaliana populations in central Spain. Colonization by Ct initiates in roots but can also spread systemically into shoots. Ct transfers the macronutrient phosphorus to shoots, promotes plant growth, and increases fertility only under phosphorus-deficient conditions, a nutrient status that might have facilitated the transition from pathogenic to beneficial lifestyles. The host’s phosphate starvation response (PSR) system controls Ct root colonization and is needed for plant growth promotion (PGP). PGP also requires PEN2-dependent indole glucosinolate metabolism, a component of innate immune responses, indicating a functional link between innate immunity and the PSR system during beneficial interactions with Ct. PMID:26997485

  12. Enhanced Labeling Techniques to Study the Cytoskeleton During Root Growth and Gravitropism

    NASA Technical Reports Server (NTRS)

    Blancaflor, Elison B.

    2005-01-01

    Gravity effects the growth and development of all living organisms. One of the most obvious manifestations of gravity's effects on biological systems lies in the ability of plants to direct their growth along a path that is dictated by the gravity vector (called gravitropism). When positioned horizontally, in florescence stems and hypocotyls in dicots, and pulvini in monocots, respond by bending upward whereas roots typically bend downward. Gravitropism allows plants to readjust their growth to maximize light absorption for photosynthesis and to more efficiently acquire water and nutrients form the soil. Despite its significance for plant survival, there are still major gaps in understanding the cellular and molecular processes by which plants respond to gravity. The major aim of this proposal was to develop improved fluorescence labeling techniques to aid in understanding how the cytoskeleton modulated plant responses to gravity.

  13. Bacillus thuringiensis colonises plant roots in a phylogeny-dependent manner.

    PubMed

    Vidal-Quist, J Cristian; Rogers, Hilary J; Mahenthiralingam, Eshwar; Berry, Colin

    2013-12-01

    Although much is known about the pathology of Bacillus thuringiensis against invertebrates, current understanding of its natural ecology is limited. This study evaluated the biodiversity of B. thuringiensis in relation to its interaction with plants. Phylogenetic relationships between 44 reference and field-collected strains, determined using 16S rRNA and gyrB gene sequences, revealed a high degree of variability, similar to that found in databases. An Arabidopsis thaliana in vitro inoculation model was developed to screen the ability of B. thuringiensis to colonise roots. Significant colonisation differences up to 91-fold were observed between strains, and correlation between strain phylogeny and colonisation was found. The genetics and biochemistry of auxin production; presence of the gene encoding indole pyruvate decarboxylase; and the abilities of Bt strains to swarm, grow in rich/minimal media and affect root growth differed between the strains, but only auxin production correlated significantly with ability to colonise roots. Co-inoculation with Burkholderia phytofirmans PsJN or Pseudomonas fluorescens SBW25 produced no effect on B. thuringiensis colonisation levels, regardless of the co-inoculant. Similarly, root colonisation of A. thaliana mutants impaired in plant defences was not significantly higher compared with controls. This is the first systematic and phylogenetic evaluation of B. thuringiensis interaction with plants. PMID:23822207

  14. Traits of fluorescent Pseudomonas spp. involved in suppression of plant root pathogens.

    PubMed Central

    O'Sullivan, D J; O'Gara, F

    1992-01-01

    Certain members of the fluorescent pseudomonad group have been shown to be potential agents for the biocontrol of plant root diseases. The major problems with the commercialization of these beneficial strains are that few wild-type strains contain all the desired characteristics for this process and the performance of strains in different soil and climatic conditions is not reproducible. Consequently, prior to selection and/or improvement of suitable strains for biocontrol purposes, it is necessary to understand the important traits required for this purpose. The production of fluorescent siderophores (iron-binding compounds) and antibiotic compounds has been recognized as important for the inhibition of plant root pathogens. Efficient root colonization is also a prerequisite for successful biocontrol strains. This review discusses some of the characteristics of fluorescent pseudomonads that have been suggested to be important for biocontrol. The genetic organization and regulation of these processes is also examined. This information is necessary for attempts aimed at the improvement of strains based on deregulating pathways or introducing traits from one strain to another. The release of genetically engineered organisms into the environment is governed by regulations, and this aspect is summarized. The commercialization of fluorescent pseudomonads for the biological control of plant root diseases remains an exciting possibility. The understanding of the relevant characteristics will facilitate this process by enabling the direct selection and/or construction of strains which will perform under a variety of environmental conditions. PMID:1480114

  15. Characterisation of bacteria from Pinus sylvestris-Suillus luteus mycorrhizas and their effects on root-fungus interactions and plant growth.

    PubMed

    Bending, Gary D; Poole, Elizabeth J; Whipps, John M; Read, David J

    2002-03-01

    Bacteria from Pinus sylvestris-Suillus luteus mycorrhizas were isolated, characterised, and their effects on P. sylvestris-S. luteus interactions and plant growth investigated in vitro. The isolates formed five distinct phenotypic and physiological groups. Two of the groups, accounting for 34 of the 55 isolates, consisted of Bacillus spp., with three subgroups represented. The other groups contained Burkholderia spp., Serratia spp. and Pseudomonas spp. Representatives from each bacterial group were used in microcosm experiments to investigate bacterial effects on P. sylvestris-S. luteus interactions. Most Bacillus isolates stimulated growth of S. luteus along the P. sylvestris root, while isolates of Pseudomonas and Serratia inhibited root colonisation by the fungus. Burkholderia and Serratia isolates inhibited ectomycorrhiza formation by 97 and 41% respectively, while a single Bacillus isolate doubled the formation of first order ectomycorrhizal roots. There were no clear relationships between effects of the bacteria on root colonisation by the fungus after 4 weeks, and chitinase production or subsequent ectomycorrhiza formation. However, isolates that inhibited ectomycorrhiza formation appeared to associate preferentially with ectomycorrhizal roots. Several isolates enhanced plant growth substantially, although these effects were unrelated to either root colonisation by the fungus or ectomycorrhiza formation. PMID:19709201

  16. Heat and mass transfer in the vadose zone with plant roots

    NASA Astrophysics Data System (ADS)

    Sung, Kijune; Yavuz, Corapcioglu M.; Drew, Malcolm C.

    2002-07-01

    The vadose zone is the intermediate medium between the atmosphere and groundwater. The modeling of the processes taking place in the vadose zone needs different approaches to those needed for groundwater transport problems because of the marked changes in environmental conditions affecting the vadose zone. A mathematical model to simulate the water flow, and the fate and transport of recalcitrant contaminants was developed, which could be applied to various bioremediation methods such as phytoremediation and natural attenuation in the vadose zone. Two-phase flow equations and heat flux models were used to develop the model. Surface energy balance equations were used to estimate soil surface temperature, and root growth and root distribution models were incorporated to represent the special contribution of plant roots in the vegetated soils. Interactions between the roots and environmental conditions such as temperature and water content were treated by incorporating a feedback mechanism that made allowance for the effects of water and temperature stresses on root distribution and water uptake by roots. In conducting the modeling study, Johnson grass and unplanted soil were simulated to compare the effect of root water uptake on soil water content. After the numerical experiments were conducted to investigate model behavior, the proposed model was applied to estimate actual water flow and heat flow in field lysimeter experiments over a 1-year period. Root growth and distribution for Johnson grass and rye grass were simulated to compare the warm season grass to the cold season grass. A significant agreement was observed between the simulations and measured data.

  17. Integrated metabolomics and transcriptomics reveal enhanced specialized metabolism in Medicago truncatula root border cells.

    PubMed

    Watson, Bonnie S; Bedair, Mohamed F; Urbanczyk-Wochniak, Ewa; Huhman, David V; Yang, Dong Sik; Allen, Stacy N; Li, Wensheng; Tang, Yuhong; Sumner, Lloyd W

    2015-04-01

    Integrated metabolomics and transcriptomics of Medicago truncatula seedling border cells and root tips revealed substantial metabolic differences between these distinct and spatially segregated root regions. Large differential increases in oxylipin-pathway lipoxygenases and auxin-responsive transcript levels in border cells corresponded to differences in phytohormone and volatile levels compared with adjacent root tips. Morphological examinations of border cells revealed the presence of significant starch deposits that serve as critical energy and carbon reserves, as documented through increased β-amylase transcript levels and associated starch hydrolysis metabolites. A substantial proportion of primary metabolism transcripts were decreased in border cells, while many flavonoid- and triterpenoid-related metabolite and transcript levels were increased dramatically. The cumulative data provide compounding evidence that primary and secondary metabolism are differentially programmed in border cells relative to root tips. Metabolic resources normally destined for growth and development are redirected toward elevated accumulation of specialized metabolites in border cells, resulting in constitutively elevated defense and signaling compounds needed to protect the delicate root cap and signal motile rhizobia required for symbiotic nitrogen fixation. Elevated levels of 7,4'-dihydroxyflavone were further increased in border cells of roots exposed to cotton root rot (Phymatotrichopsis omnivora), and the value of 7,4'-dihydroxyflavone as an antimicrobial compound was demonstrated using in vitro growth inhibition assays. The cumulative and pathway-specific data provide key insights into the metabolic programming of border cells that strongly implicate a more prominent mechanistic role for border cells in plant-microbe signaling, defense, and interactions than envisioned previously. PMID:25667316

  18. Integrated Metabolomics and Transcriptomics Reveal Enhanced Specialized Metabolism in Medicago truncatula Root Border Cells1[OPEN

    PubMed Central

    Watson, Bonnie S.; Bedair, Mohamed F.; Urbanczyk-Wochniak, Ewa; Huhman, David V.; Yang, Dong Sik; Allen, Stacy N.; Li, Wensheng; Tang, Yuhong; Sumner, Lloyd W.

    2015-01-01

    Integrated metabolomics and transcriptomics of Medicago truncatula seedling border cells and root tips revealed substantial metabolic differences between these distinct and spatially segregated root regions. Large differential increases in oxylipin-pathway lipoxygenases and auxin-responsive transcript levels in border cells corresponded to differences in phytohormone and volatile levels compared with adjacent root tips. Morphological examinations of border cells revealed the presence of significant starch deposits that serve as critical energy and carbon reserves, as documented through increased β-amylase transcript levels and associated starch hydrolysis metabolites. A substantial proportion of primary metabolism transcripts were decreased in border cells, while many flavonoid- and triterpenoid-related metabolite and transcript levels were increased dramatically. The cumulative data provide compounding evidence that primary and secondary metabolism are differentially programmed in border cells relative to root tips. Metabolic resources normally destined for growth and development are redirected toward elevated accumulation of specialized metabolites in border cells, resulting in constitutively elevated defense and signaling compounds needed to protect the delicate root cap and signal motile rhizobia required for symbiotic nitrogen fixation. Elevated levels of 7,4′-dihydroxyflavone were further increased in border cells of roots exposed to cotton root rot (Phymatotrichopsis omnivora), and the value of 7,4′-dihydroxyflavone as an antimicrobial compound was demonstrated using in vitro growth inhibition assays. The cumulative and pathway-specific data provide key insights into the metabolic programming of border cells that strongly implicate a more prominent mechanistic role for border cells in plant-microbe signaling, defense, and interactions than envisioned previously. PMID:25667316

  19. Genetic Based Plant Resistance and Susceptibility Traits to Herbivory Influence Needle and Root Litter Nutrient Dynamics

    SciTech Connect

    Classen, Aimee T; Chapman, Samantha K.; Whitham, Thomas G; Hart, Stephen C; Koch, George W

    2007-01-01

    It is generally assumed that leaf and root litter decomposition have similar drivers and that nutrient release from these substrates is synchronized. Few studies have examined these assumptions, and none has examined how plant genetics (i.e., plant susceptibility to herbivory) could affect these relationships. Here we examine the effects of herbivore susceptibility and resistance on needle and fine root litter decomposition of pi on pine, Pinus edulis. The study population consists of individual trees that are either susceptible or resistant to herbivory by the pi on needle scale, Matsucoccus acalyptus, or the stem-boring moth, Dioryctria albovittella. Genetic analyses and experimental removals and additions of these insects have identified trees that are naturally resistant and susceptible to these insects. These herbivores increase the chemical quality of litter inputs and alter soil microclimate, both of which are important decomposition drivers. Our research leads to four major conclusions: Herbivore susceptibility and resistance effects on 1) needle litter mass loss and phosphorus (P) retention in moth susceptible and resistant litter are governed by microclimate, 2) root litter nitrogen (N) and P retention, and needle litter N retention are governed by litter chemical quality, 3) net nutrient release from litter can reverse over time, 4) root and needle litter mass loss and nutrient release are determined by location (above- vs. belowground), suggesting that the regulators of needle and root decomposition differ at the local scale. Understanding of decomposition and nutrient retention in ecosystems requires consideration of herbivore effects on above- and belowground processes and how these effects may be governed by plant genotype. Because an underlying genetic component to herbivory is common to most ecosystems of the world and herbivory may increase in climatic change scenarios, it is important to evaluate the role of plant genetics in affecting carbon and

  20. Tetraploid Rangpur lime rootstock increases drought tolerance via enhanced constitutive root abscisic acid production.

    PubMed

    Allario, Thierry; Brumos, Javier; Colmenero-Flores, Jose M; Iglesias, Domingo J; Pina, Jose A; Navarro, Luis; Talon, Manuel; Ollitrault, Patrick; Morillon, Raphaël

    2013-04-01

    Whole-genome duplication, or polyploidy, is common in many plant species and often leads to better adaptation to adverse environmental condition. However, little is known about the physiological and molecular determinants underlying adaptation. We examined the drought tolerance in diploid (2x) and autotetraploid (4x) clones of Rangpur lime (Citrus limonia) rootstocks grafted with 2x Valencia Delta sweet orange (Citrus sinensis) scions, named V/2xRL and V/4xRL, respectively. Physiological experiments to study root-shoot communication associated with gene expression studies in roots and leaves were performed. V/4xRL was much more tolerant to water deficit than V/2xRL. Gene expression analysis in leaves and roots showed that more genes related to the response to water stress were differentially expressed in V/2xRL than in V/4xRL. Prior to the stress, when comparing V/4xRL to V/2xRL, V/4xRL leaves had lower stomatal conductance and greater abscisic acid (ABA) content. In roots, ABA content was higher in V/4xRL and was associated to a greater expression of drought responsive genes, including CsNCED1, a pivotal regulatory gene of ABA biosynthesis. We conclude that tetraploidy modifies the expression of genes in Rangpur lime citrus roots to regulate long-distance ABA signalling and adaptation to stress. PMID:23050986

  1. Over-expression of the Arabidopsis proton-pyrophosphatase AVP1 enhances transplant survival, root mass, and fruit development under limiting phosphorus conditions

    PubMed Central

    Yang, Haibing; Zhang, Xiao; Gaxiola, Roberto A.; Xu, Guohua; Peer, Wendy Ann; Murphy, Angus S.

    2014-01-01

    Phosphorus (P), an element required for plant growth, fruit set, fruit development, and fruit ripening, can be deficient or unavailable in agricultural soils. Previously, it was shown that over-expression of a proton-pyrophosphatase gene AVP1/AVP1D (AVP1DOX) in Arabidopsis, rice, and tomato resulted in the enhancement of root branching and overall mass with the result of increased mineral P acquisition. However, although AVP1 over-expression also increased shoot biomass in Arabidopsis, this effect was not observed in tomato under phosphate-sufficient conditions. AVP1DOX tomato plants exhibited increased rootward auxin transport and root acidification compared with control plants. AVP1DOX tomato plants were analysed in detail under limiting P conditions in greenhouse and field trials. AVP1DOX plants produced 25% (P=0.001) more marketable ripened fruit per plant under P-deficient conditions compared with the controls. Further, under low phosphate conditions, AVP1DOX plants displayed increased phosphate transport from leaf (source) to fruit (sink) compared to controls. AVP1DOX plants also showed an 11% increase in transplant survival (P<0.01) in both greenhouse and field trials compared with the control plants. These results suggest that selection of tomato cultivars for increased proton pyrophosphatase gene expression could be useful when selecting for cultivars to be grown on marginal soils. PMID:24723407

  2. Fusarium Oxysporum Volatiles Enhance Plant Growth Via Affecting Auxin Transport and Signaling

    PubMed Central

    Bitas, Vasileios; McCartney, Nathaniel; Li, Ningxiao; Demers, Jill; Kim, Jung-Eun; Kim, Hye-Seon; Brown, Kathleen M.; Kang, Seogchan

    2015-01-01

    Volatile organic compounds (VOCs) have well-documented roles in plant-plant communication and directing animal behavior. In this study, we examine the less understood roles of VOCs in plant-fungal relationships. Phylogenetically and ecologically diverse strains of Fusarium oxysporum, a fungal species complex that often resides in the rhizosphere of assorted plants, produce volatile compounds that augment shoot and root growth of Arabidopsis thaliana and tobacco. Growth responses of A. thaliana hormone signaling mutants and expression patterns of a GUS reporter gene under the auxin-responsive DR5 promoter supported the involvement of auxin signaling in F. oxysporum volatile-mediated growth enhancement. In addition, 1-naphthylthalamic acid, an inhibitor of auxin efflux, negated F. oxysporum volatile-mediated growth enhancement in both plants. Comparison of the profiles of volatile compounds produced by F. oxysporum strains that differentially affected plant growth suggests that the relative compositions of both growth inhibitory and stimulatory compounds may determine the degree of plant growth enhancement. Volatile-mediated signaling between fungi and plants may represent a potentially conserved, yet mostly overlooked, mechanism underpinning plant-fungus interactions and fungal niche adaption. PMID:26617587

  3. Lignan enhancement in hairy root cultures of Linum album using coniferaldehyde and methylenedioxycinnamic acid.

    PubMed

    Ahmadian Chashmi, Najmeh; Sharifi, Mohsen; Behmanesh, Mehrdad

    2016-07-01

    Feeding experiments with hairy root cultures of Linum album have established that the extracellular coniferaldehyde is a good precursor for production of two lignans: lariciresinol (LARI) and pinoresinol (PINO). The accumulation of the LARI, PINO, and podophyllotoxin (PTOX) in hairy roots were enhanced about 14.8-, 8.7-, and 1.5-fold (107.61, 8.7 and 6.42 µg g(-1) Fresh Wight), respectively, by the addition of coniferaldehyde (2 mM) to the culture media (after 24 hr). This result was correlated with an increase pinoresinol/lariciresinol reductase (PLR) expression gene and cinnamyl alcohol dehydrogenase (CAD) activity in the fed hairy roots. Adding 3,4-(methylendioxy)cinnamic acid (MDCA) precursor did not influence on the lignans accumulation, but the lignin content of the hairy roots was increased. Moreover, the expression genes of phenylalanine ammonialyase (PAL), CAD, and cinnamoyl-CoA reductase (CCR) were influenced after feeding hairy roots with MDCA. PMID:26444150

  4. Enhancement of reproductive heat tolerance in plants.

    PubMed

    Burke, John J; Chen, Junping

    2015-01-01

    Comparison of average crop yields with reported record yields has shown that major crops exhibit annual average yields three- to seven-fold lower than record yields because of unfavorable environments. The current study investigated the enhancement of pollen heat tolerance through expressing an Arabidopsis thaliana heat shock protein 101 (AtHSP101) that is not normally expressed in pollen but reported to play a crucial role in vegetative thermotolerance. The AtHSP101 construct under the control of the constitutive ocs/mas 'superpromoter' was transformed into cotton Coker 312 and tobacco SRI lines via Agrobacterium mediated transformation. Thermotolerance of pollen was evaluated by in vitro pollen germination studies. Comparing with those of wild type and transgenic null lines, pollen from AtHSP101 transgenic tobacco and cotton lines exhibited significantly higher germination rate and much greater pollen tube elongation under elevated temperatures or after a heat exposure. In addition, significant increases in boll set and seed numbers were also observed in transgenic cotton lines exposed to elevated day and night temperatures in both greenhouse and field studies. The results of this study suggest that enhancing heat tolerance of reproductive tissues in plant holds promise in the development of crops with improved yield production and yield sustainability in unfavorable environments. PMID:25849955

  5. Enhancement of Reproductive Heat Tolerance in Plants

    PubMed Central

    Burke, John J.; Chen, Junping

    2015-01-01

    Comparison of average crop yields with reported record yields has shown that major crops exhibit annual average yields three- to seven-fold lower than record yields because of unfavorable environments. The current study investigated the enhancement of pollen heat tolerance through expressing an Arabidopsis thaliana heat shock protein 101 (AtHSP101) that is not normally expressed in pollen but reported to play a crucial role in vegetative thermotolerance. The AtHSP101 construct under the control of the constitutive ocs/mas ‘superpromoter’ was transformed into cotton Coker 312 and tobacco SRI lines via Agrobacterium mediated transformation. Thermotolerance of pollen was evaluated by in vitro pollen germination studies. Comparing with those of wild type and transgenic null lines, pollen from AtHSP101 transgenic tobacco and cotton lines exhibited significantly higher germination rate and much greater pollen tube elongation under elevated temperatures or after a heat exposure. In addition, significant increases in boll set and seed numbers were also observed in transgenic cotton lines exposed to elevated day and night temperatures in both greenhouse and field studies. The results of this study suggest that enhancing heat tolerance of reproductive tissues in plant holds promise in the development of crops with improved yield production and yield sustainability in unfavorable environments. PMID:25849955

  6. Confirmation of conjugation processes during TNT metabolism by axenic plant roots

    SciTech Connect

    Bhadra, R.; Wayment, D.G.; Hughes, J.B.; Shanks, J.V.

    1999-02-01

    This paper examines processes in plants for the formation of fate products of TNT beyond its animated reduction products, 2-amino-4,6-dinitrotoluene and 4-amino-2,6-dinitrotoluene. TNT metabolites were isolated and characterized in combination with temporal analyses of production profiles and {sup 14}C distribution, in microbe-free, axenic root cultures of Catharanthus roseus. Four unique TNT-derived compounds were isolated. Using evidence from {sup 1}H NMR, mass spectroscopy, HPLC, acid hydrolysis, and enzymatic hydrolysis with {beta}-glucuronidase and {beta}-glucosidase, they were established as conjugates formed by reactions of the amine groups of 2-amino-4,6-dinitrotoluene and 4-amino-2,6-dinitrotoluene. From the mass spectral evidence, at least a six-carbon unit from the plant intracellular milleu was involved in conjugate formation. Mass balance analysis indicated that, by 75 h after TNT amendment of the initial TNT radiolabel, extractable conjugates comprised 22%, bound residues comprised another 29%, 2-amino-4,6-dinitrotoluene was 4%, and the rest remained unidentified. Isolates from TNT-amended roots versus monoamino-dinitrotoluene-amended roots were not identical, suggesting numerous possible outcomes for the plant-based conjugation of 2-amino-2,6-dinitrotoluene or 4-amino-2,6-dinitrotoluene. This study is the first direct evidence for the involvement of the primary reduction products of TNT--2-amino-4,6-dinitrotoluene ad 4-amino--2,6-dinitrotoluene--in conjugation process in plant detoxification of TNT.

  7. Somatic embryogenesis and plant regeneration in Carica papaya L. tissue culture derived from root explants.

    PubMed

    Chen, M H; Wang, P J; Maeda, E

    1987-10-01

    The regeneration potential of shoot tip, stem, leaf, cotyledon and root explants of two papaya cultivars (Carica papaya cv. 'Solo' and cv. 'Sunrise') were studed. Callus induction of these two cultivars of papaya showed that the shoot tips and stems are most suitable for forming callus, while leaves, cotyledons and roots are comparatively difficult to induce callus. Callus induction also varied with the varities. Somatic embryogenesis was obtained from 3-month-old root cultures. A medium containing half strength of MS inorganic salts, 160 mg/l adenine sulfate, 1.0 mg/1 NAA, 0.5 mg/1 kinetin and 1.0 mg/1 GA3 was optimal for embryogenesis. The callus maintained high regenerative capacity after two years of culture on this medium. Plants derived from somatic embryos were obtained under green-house conditions. PMID:24248842

  8. The role of the root apoplast in aluminium-induced inhibition of root elongation and in aluminium resistance of plants: a review

    PubMed Central

    Horst, Walter J.; Wang, Yunxia; Eticha, Dejene

    2010-01-01

    Background Aluminium (Al) toxicity is the most important soil constraint for plant growth and development in acid soils. The mechanism of Al-induced inhibition of root elongation is still not well understood, and it is a matter of debate whether the primary lesions of Al toxicity are apoplastic or symplastic. Scope The present review focuses on the role of the apoplast in Al toxicity and resistance, summarizing evidence from our own experimental work and other evidence published since 1995. Conclusions The binding of Al in the cell wall particularly to the pectic matrix and to the apoplastic face of the plasma membrane in the most Al-sensitive root zone of the root apex thus impairing apoplastic and symplastic cell functions is a major factor leading to Al-induced inhibition of root elongation. Although symplastic lesions of Al toxicity cannot be excluded, the protection of the root apoplast appears to be a prerequisite for Al resistance in both Al-tolerant and Al-accumulating plant species. In many plant species the release of organic acid anions complexing Al, thus protecting the root apoplast from Al binding, is a most important Al resistance mechanism. However, there is increasing physiological, biochemical and, most recently also, molecular evidence showing that the modification of the binding properties of the root apoplast contributes to Al resistance. A further in-depth characterization of the Al-induced apoplastic reaction in the most Al-sensitive zone of the root apex is urgently required, particularly to understand the Al resistance of the most Al-resistant plant species. PMID:20237112

  9. Effect of IAA on in vitro growth and colonization of Nostoc in plant roots

    PubMed Central

    Hussain, Anwar; Shah, Syed T.; Rahman, Hazir; Irshad, Muhammad; Iqbal, Amjad

    2015-01-01

    Nostoc is widely known for its ability to fix atmospheric nitrogen and the establishment of symbiotic relationship with a wide range of plants from various taxonomic groups. Several strains of Nostoc produce phytohormones that promote growth of its plant partners. Nostoc OS-1 was therefore selected for study because of the presence of putative ipdC gene that encodes a key enzyme to produce Indole-3-acetic acid (IAA). The results indicated that both cellular and released IAA was found high with increasing incubation time and reached to a peak value (i.e., 21 pmol mg-1ch-a) on the third week as determined by UPLC-ESI-MS/MS. Also the Nostoc OS-1 strain efficiently colonized the roots and promoted the growth of rice as well as wheat under axenic conditions and induced ipdC gene that suggested the possible involvement of IAA in these phenotypes. To confirm the impact of IAA on root colonization efficiency and plant promoting phenotypes of Nostoc OS-1, an ipdC knockout mutant was generated by homologous recombinant method. The amount of releasing IAA, in vitro growth, root colonization, and plant promoting efficiency of the ipdC knockout mutant was observed significantly lower than wild type strain under axenic conditions. Importantly, these phenotypes were restored to wild-type levels when the ipdC knockout mutant was complemented with wild type ipdC gene. These results together suggested that ipdC and/or synthesized IAA of Nostoc OS-1 is required for its efficient root colonization and plant promoting activity. PMID:25699072

  10. Concentration of Petroleum-Hydrocarbon Contamination Shapes Fungal Endophytic Community Structure in Plant Roots

    PubMed Central

    Bourdel, Guillaume; Roy-Bolduc, Alice; St-Arnaud, Marc; Hijri, Mohamed

    2016-01-01

    Plant-root inhabiting fungi are a universal phenomenon found in all ecosystems where plants are able to grow, even in harsh environments. Interactions between fungi and plant roots can vary widely from mutualism to parasitism depending on many parameters. The role of fungal endophytes in phytoremediation of polluted sites, and characterization of the endophytic diversity and community assemblages in contaminated areas remain largely unexplored. In this study, we investigated the composition of endophytic fungal communities in the roots of two plant species growing spontaneously in petroleum-contaminated sedimentation basins of a former petro-chemical plant. The three adjacent basins showed a highly heterogeneous pattern of pollutant concentrations. We combined a culture-based isolation approach with the pyrosequencing of fungal ITS ribosomal DNA. We selected two species, Eleocharis erythropoda Steud. and Populus balsamifera L., and sampled three individuals of each species from each of three adjacent basins, each with a different concentration of petroleum hydrocarbons. We found that contamination level significantly shaped endophytic fungal diversity and community composition in E. erythropoda, with only 9.9% of these fungal Operational Taxonomic Units (OTUs) retrieved in all three basins. However, fungal community structure associated with P. balsamifera remained unaffected by the contamination level with 28.2% of fungal OTUs shared among all three basins. This could be explained by the smaller differences of pollutant concentrations in the soil around our set of P. balsamifera sampless compared to that around our set of E. erythropoda samples. Our culture-based approach allowed isolation of 11 and 30 fungal endophytic species from surface-sterilized roots of E. erythropoda and P. balsamifera, respectively. These isolates were ribotyped using ITS, and all were found in pyrosequensing datasets. Our results demonstrate that extreme levels of pollution reduce fungal

  11. Root growth, mycorrhization and physiological effects of plants growing on oil tailing sands

    NASA Astrophysics Data System (ADS)

    Boldt-Burisch, Katja M.; Naeth, Anne M.; Schneider, Bernd Uwe; Hüttl, Reinhard F.

    2015-04-01

    Surface mining creates large, intense disturbances of soils and produces large volumes of by-products and waste materials. After mining processes these materials often provide the basis for land reclamation and ecosystem restoration. In the present study, tailing sands (TS) and processed mature fine tailings (pMFT) from Fort McMurray (Alberta, Canada) were used. They represent challenging material for ecosystem rebuilding because of very low nutrient contents of TS and oil residuals, high density of MFT material. In this context, little is known about the interactions of pure TS, respectively mixtures of TS and MFT and root growth, mycorrhization and plant physiological effects. Four herbaceous plant species (Elymus trachycaulus, Koeleria macrantha, Deschampsia cespitosa, Lotus corniculatus) were chosen to investigate root development, chlorophyll fluorescence and mycorrhization intensity with and without application of Glomus mosseae (arbuscular mycorrhizae) on mainly tailing sands. Surprisingly both, plants growing on pure TS and plants growing on TS with additional AM-application showed mycorrhization of roots. In general, the mycorrhization intensity was lower for plants growing on pure tailings sands, but it is an interesting fact that there is a potential for mycorrhization available in tailing sands. The mycorrhizal intensity strongly increased with application of G. mosseae for K. macrantha and L. corniculatus and even more for E. trachycaulus. For D. cespitosa similar high mycorrhiza infection frequency was found for both variants, with and without AM-application. By the application of G. mosseae, root growth of E. trachycaulus and K. macrantha was significantly positively influenced. Analysis of leaf chlorophyll fluorescence showed no significant differences for E. trachycaulus but significant positive influence of mycorrhizal application on the physiological status of L. corniculatus. However, this effect could not be detected when TS was mixed with MFT

  12. Concentration of Petroleum-Hydrocarbon Contamination Shapes Fungal Endophytic Community Structure in Plant Roots.

    PubMed

    Bourdel, Guillaume; Roy-Bolduc, Alice; St-Arnaud, Marc; Hijri, Mohamed

    2016-01-01

    Plant-root inhabiting fungi are a universal phenomenon found in all ecosystems where plants are able to grow, even in harsh environments. Interactions between fungi and plant roots can vary widely from mutualism to parasitism depending on many parameters. The role of fungal endophytes in phytoremediation of polluted sites, and characterization of the endophytic diversity and community assemblages in contaminated areas remain largely unexplored. In this study, we investigated the composition of endophytic fungal communities in the roots of two plant species growing spontaneously in petroleum-contaminated sedimentation basins of a former petro-chemical plant. The three adjacent basins showed a highly heterogeneous pattern of pollutant concentrations. We combined a culture-based isolation approach with the pyrosequencing of fungal ITS ribosomal DNA. We selected two species, Eleocharis erythropoda Steud. and Populus balsamifera L., and sampled three individuals of each species from each of three adjacent basins, each with a different concentration of petroleum hydrocarbons. We found that contamination level significantly shaped endophytic fungal diversity and community composition in E. erythropoda, with only 9.9% of these fungal Operational Taxonomic Units (OTUs) retrieved in all three basins. However, fungal community structure associated with P. balsamifera remained unaffected by the contamination level with 28.2% of fungal OTUs shared among all three basins. This could be explained by the smaller differences of pollutant concentrations in the soil around our set of P. balsamifera sampless compared to that around our set of E. erythropoda samples. Our culture-based approach allowed isolation of 11 and 30 fungal endophytic species from surface-sterilized roots of E. erythropoda and P. balsamifera, respectively. These isolates were ribotyped using ITS, and all were found in pyrosequensing datasets. Our results demonstrate that extreme levels of pollution reduce fungal

  13. Hydrogeophysical Monitoring of Water Uptake in Root Zones of Small Plants

    NASA Astrophysics Data System (ADS)

    Al Hagrey, S.; Werban, U.; Meissner, R.; Ismaeil, A.; Rabbel, W.

    2005-05-01

    We have monitored the water content in root zones in hydrogeophysical experiments and studied daily and seasonal variations of water uptake. Plants grew in plastic pots filled with fine sand. The surface of the pots was isolated to minimize evaporation, i.e., most water is consumed for transpiration. We installed geoelectric surface and subsurface profiles (electrode interval = 1.5 cm), and used 900/1500 MHz antennas to measure the travel times of radar waves reflected from a metallic plate at the base. Also a central and peripheral TDR and a tensiometer probe were installed. A continuous data acquisition was conducted to monitor the spatiotemporal water content of root zones and its variations. Our observations clearly reflect a decrease of pore water content with time and its abrupt increase directly after each irrigation cycle. TDR and tensiometer curves are parallel and mirror images of the resistivity curve. Observed soil water content in the day time was consistently lower than in the night time (no plant transpiration). Long-term observations of water uptake by roots show that the plants behavior is a function of the background moisture content. The maximum water uptake of optimum growth occurs at intermediate water content. Seasonal variations could be observed. The water uptake in May is obviously twice that of November. This can be explained by the fact that the available light (required for photosynthesis) was higher in May than in November. Also the effect of day light on the water uptake can be observed. The light sunny days show higher water uptake than the dark rainy days. The peripheral water content values that decrease with time are lower than that of the central root zone and show small night and day changes. This may imply that the central TDR probe measures the water content both within the wet root branches and the bounding soils, whereas the peripheral TDR reading represents the soil pore water only. Electrical models of the root zone show a

  14. Water flow and solute transport in the soil-plant-atmosphere continuum: Upscaling from rhizosphere to root zone

    NASA Astrophysics Data System (ADS)

    Lazarovitch, Naftali; Perelman, Adi; Guerra, Helena; Vanderborght, Jan; Pohlmeier, Andreas

    2016-04-01

    Root water and nutrient uptake are among the most important processes considered in numerical models simulating water content and fluxes in the subsurface, as they control plant growth and production as well as water flow and nutrient transport out of the root zone. Root water uptake may lead to salt accumulation at the root-soil interface, resulting in rhizophere salt concentrations much higher than in the bulk soil. This salt accumulation is caused by soluble salt transport towards the roots by mass flow through the soil, followed by preferential adsorption of specific nutrients by active uptake, thereby excluding most other salts at the root-soil interface or in the root apoplast. The salinity buildup can lead to large osmotic pressure gradients across the roots thereby effectively reducing root water uptake. The initial results from rhizoslides (capillary paper growth system) show that sodium concentration is decreasing with distance from the root, compared with the bulk that remained more stable. When transpiration rate was decreased under high salinity levels, sodium concentration was more homogenous compared with low salinity levels. Additionally, sodium and gadolinium distributions were measured nondestructively around tomato roots using magnetic resonance imaging (MRI). This technique could also observe the root structure and water content around single roots. Results from the MRI confirm the solutes concentration pattern around roots and its relation to their initial concentration. We conclude that local water potentials at the soil-root interface differ from bulk potentials. These relative differences increase with decreasing root density, decreasing initial salt concentration and increasing transpiration rate. Furthermore, since climate may significantly influence plant response to salinity a dynamic climate-coupled salinity reduction functions are critical in while using macroscopic numerical models.

  15. Measurement of Differential Na+ Efflux from Apical and Bulk Root Zones of Intact Barley and Arabidopsis Plants

    PubMed Central

    Hamam, Ahmed M.; Britto, Dev T.; Flam-Shepherd, Rubens; Kronzucker, Herbert J.

    2016-01-01

    Rapid sodium cycling across the plasma membrane of root cells is widely thought to be associated with Na+ toxicity in plants. However, the efflux component of this cycling is not well understood. Efflux of Na+ from root cells is believed to be mediated by Salt Overly-Sensitive-1, although expression of this Na+/H+ antiporter has been localized to the vascular tissue and root meristem. Here, we used a chambered cuvette system in which the distal root of intact salinized barley and Arabidopsis thaliana plants (wild-type and sos1) were isolated from the bulk of the root by a silicone-acrylic barrier, so that we could compare patterns of 24Na+ efflux in these two regions of root. In barley, steady-state release of 24Na+ was about four times higher from the distal root than from the bulk roots. In the distal root, 24Na+ release was pronouncedly decreased by elevated pH (9.2), while the bulk-root release was not significantly affected. In A. thaliana, tracer efflux was about three times higher from the wild-type distal root than from the wild-type bulk root and also three to four times higher than both distal- and bulk-root fluxes of Atsos1 mutants. Elevated pH also greatly reduced the efflux from wild-type roots. These findings support a significant role of SOS1-mediated Na+ efflux in the distal root, but not in the bulk root. PMID:27014297

  16. Plant root-driven hydraulic redistribution, root nutrient uptake and carbon exudation interact with soil properties to generate rhizosphere resource hotspots that vary in space and time

    NASA Astrophysics Data System (ADS)

    Espeleta, J. F.; Neumann, R. B.; Cardon, Z. G.; Mayer, K. U.; Rastetter, E. B.

    2014-12-01

    Hydraulic redistribution (HR) of soil water by plants occurs in seasonally dry ecosystems worldwide. During drought, water flows from deep moist soil, through plant roots, into dry (often litter-rich) upper soil layers. Using modeling, we explored how physical transport processes driven by transpiration and hydraulic redistribution interact with root physiology (nutrient uptake and carbon exudation) and soil properties (soil texture and cation exchange) to influence nitrogen and carbon concentrations in the rhizosphere. At the single root scale, we modeled a 10-cm radial soil domain, and simulated solute transport, soil cation exchange, and root exudation and nutrient uptake under two water flow patterns: daytime transpiration without nighttime HR, and daytime transpiration with nighttime HR. During HR, water efflux flushed solutes away from the root, diluting the concentrations of key nutrients like nitrate. The transport of cations by transpiration in the day and their accumulation near the root led to competitive desorption of ammonium from soil further from the root and generation of hotspots of ammonium availability at night. HR influenced the spatial and temporal patterns of these hotspots and their intensity. They were also influenced by soil properties of texture and cation exchange capacity. This dynamic resource landscape caused by diel cycling between transpiration and hydraulic redistribution presents a stage for greater complexity of microbial interactions. We are currently embedding a microbial community and small food web into this rhizosphere model in order to explore how organisms responsible for nutrient and soil carbon cycling respond to these fluctuating resource regimes.

  17. Mathematical Modeling of the Dynamics of Shoot-Root Interactions and Resource Partitioning in Plant Growth

    PubMed Central

    Feller, Chrystel; Favre, Patrick; Janka, Ales; Zeeman, Samuel C.; Gabriel, Jean-Pierre; Reinhardt, Didier

    2015-01-01

    Plants are highly plastic in their potential to adapt to changing environmental conditions. For example, they can selectively promote the relative growth of the root and the shoot in response to limiting supply of mineral nutrients and light, respectively, a phenomenon that is referred to as balanced growth or functional equilibrium. To gain insight into the regulatory network that controls this phenomenon, we took a systems biology approach that combines experimental work with mathematical modeling. We developed a mathematical model representing the activities of the root (nutrient and water uptake) and the shoot (photosynthesis), and their interactions through the exchange of the substrates sugar and phosphate (Pi). The model has been calibrated and validated with two independent experimental data sets obtained with Petunia hybrida. It involves a realistic environment with a day-and-night cycle, which necessitated the introduction of a transitory carbohydrate storage pool and an endogenous clock for coordination of metabolism with the environment. Our main goal was to grasp the dynamic adaptation of shoot:root ratio as a result of changes in light and Pi supply. The results of our study are in agreement with balanced growth hypothesis, suggesting that plants maintain a functional equilibrium between shoot and root activity based on differential growth of these two compartments. Furthermore, our results indicate that resource partitioning can be understood as the emergent property of many local physiological processes in the shoot and the root without explicit partitioning functions. Based on its encouraging predictive power, the model will be further developed as a tool to analyze resource partitioning in shoot and root crops. PMID:26154262

  18. Mathematical Modeling of the Dynamics of Shoot-Root Interactions and Resource Partitioning in Plant Growth.

    PubMed

    Feller, Chrystel; Favre, Patrick; Janka, Ales; Zeeman, Samuel C; Gabriel, Jean-Pierre; Reinhardt, Didier

    2015-01-01

    Plants are highly plastic in their potential to adapt to changing environmental conditions. For example, they can selectively promote the relative growth of the root and the shoot in response to limiting supply of mineral nutrients and light, respectively, a phenomenon that is referred to as balanced growth or functional equilibrium. To gain insight into the regulatory network that controls this phenomenon, we took a systems biology approach that combines experimental work with mathematical modeling. We developed a mathematical model representing the activities of the root (nutrient and water uptake) and the shoot (photosynthesis), and their interactions through the exchange of the substrates sugar and phosphate (Pi). The model has been calibrated and validated with two independent experimental data sets obtained with Petunia hybrida. It involves a realistic environment with a day-and-night cycle, which necessitated the introduction of a transitory carbohydrate storage pool and an endogenous clock for coordination of metabolism with the environment. Our main goal was to grasp the dynamic adaptation of shoot:root ratio as a result of changes in light and Pi supply. The results of our study are in agreement with balanced growth hypothesis, suggesting that plants maintain a functional equilibrium between shoot and root activity based on differential growth of these two compartments. Furthermore, our results indicate that resource partitioning can be understood as the emergent property of many local physiological processes in the shoot and the root without explicit partitioning functions. Based on its encouraging predictive power, the model will be further developed as a tool to analyze resource partitioning in shoot and root crops. PMID:26154262

  19. Auxin: a major player in the shoot-to-root regulation of root Fe-stress physiological responses to Fe deficiency in cucumber plants.

    PubMed

    Bacaicoa, Eva; Mora, Verónica; Zamarreño, Angel María; Fuentes, Marta; Casanova, Esther; García-Mina, José María

    2011-05-01

    The aim of this study was to investigate the effects of IAA and ABA in the shoot-to-root regulation of the expression of the main Fe-stress physiological root responses in cucumber plants subjected to shoot Fe functional deficiency. Changes in the expression of the genes CsFRO1, CsIRT1, CsHA1 and CsHA2 (coding for Fe(III)-chelate reductase (FCR), the Fe(II) transporter and H+-ATPase, respectively) and in the enzyme activity of FCR and the acidification capacity were measured. We studied first the ability of exogenous applications of IAA and ABA to induce these Fe-stress root responses in plants grown in Fe-sufficient conditions. The results showed that IAA was able to activate these responses at the transcriptional and functional levels, whereas the results with ABA were less conclusive. Thereafter, we explored the role of IAA in plants with or without shoot Fe functional deficiency in the presence of two types of IAA inhibitors, affecting either IAA polar transport (TIBA) or IAA functionality (PCIB). The results showed that IAA is involved in the regulation at the transcriptional and functional levels of both Fe root acquisition (FCR, Fe(II) transport) and rhizosphere acidification (H+-ATPase), although through different, and probably complementary, mechanisms. These results suggest that IAA is involved in the shoot-to-root regulation of the expression of Fe-stress physiological root responses. PMID:21411331

  20. Cadmium stress antioxidant responses and root-to-shoot communication in grafted tomato plants.

    PubMed

    Gratão, Priscila Lupino; Monteiro, Carolina Cristina; Tezotto, Tiago; Carvalho, Rogério Falleiros; Alves, Letícia Rodrigues; Peters, Leila Priscila; Azevedo, Ricardo Antunes

    2015-10-01

    Many aspects related to ROS modulation of signaling networks and biological processes that control stress responses still remain unanswered. For this purpose, the grafting technique may be a powerful tool to investigate stress signaling and specific responses between plant organs during stress. In order to gain new insights on the modulation of antioxidant stress responses mechanisms, gas-exchange measurements, lipid peroxidation, H2O2 content, proline, superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), ascorbate peroxidase (APX) and guaiacol peroxidase (GPOX) were analyzed in Micro-Tom grafted plants submitted to cadmium (Cd). The results observed revealed that higher amounts of Cd accumulated mainly in the roots and rootstocks when compared to leaves and scions. Macronutrients uptake (Ca, S, P and Mg) decreased in non-grafted plants, but differed among plant parts in all grafted plants. The results showed that the accumulation of proline observed in scions of grafted plants could be associated to the lower MDA contents in the scions of grafted plants. In the presence of Cd, non-grafted plants displayed increased CAT, GR, GPOX and APX activities for both tissues, whilst grafted plants revealed distinct trends that clearly indicate signaling responses from the rootstocks, allowing sufficient time to activate defense mechanisms in shoot. The information available concerning plants subjected to grafting can provide a better understanding of the mechanisms of Cd detoxification involving root-to-shoot signaling, opening new possibilities on strategies which can be used to manipulate heavy metal tolerance, since antioxidant systems are directly involved in such mechanism. PMID:26077192

  1. Auxin and the integration of environmental signals into plant root development

    PubMed Central

    Kazan, Kemal

    2013-01-01

    Background Auxin is a versatile plant hormone with important roles in many essential physiological processes. In recent years, significant progress has been made towards understanding the roles of this hormone in plant growth and development. Recent evidence also points to a less well-known but equally important role for auxin as a mediator of environmental adaptation in plants. Scope This review briefly discusses recent findings on how plants utilize auxin signalling and transport to modify their root system architecture when responding to diverse biotic and abiotic rhizosphere signals, including macro- and micro-nutrient starvation, cold and water stress, soil acidity, pathogenic and beneficial microbes, nematodes and neighbouring plants. Stress-responsive transcription factors and microRNAs that modulate auxin- and environment-mediated root development are also briefly highlighted. Conclusions The auxin pathway constitutes an essential component of the plant's biotic and abiotic stress tolerance mechanisms. Further understanding of the specific roles that auxin plays in environmental adaptation can ultimately lead to the development of crops better adapted to stressful environments. PMID:24136877

  2. Balancing Water Uptake and Loss through the Coordinated Regulation of Stomatal and Root Development.

    PubMed

    Hepworth, Christopher; Turner, Carla; Landim, Marcela Guimaraes; Cameron, Duncan; Gray, Julie E

    2016-01-01

    Root development is influenced by nutrient and water availabilities. Plants are able to adjust many attributes of their root in response to environmental signals including the size and shape of the primary root, lateral roots and root hairs. Here we investigated the response of roots to changes in the levels of leaf transpiration associated with altered stomatal frequency. We found that plants with high stomatal density and conductance produce a larger rooting area and as a result have enhanced phosphate uptake capacity whereas plants with low stomatal conductance produce a smaller root. Manipulating the growth environment of plants indicated that enhanced root growth is most likely a result of an increased demand for water rather than phosphate. Plants manipulated to have an increase or reduction in root hair growth show a reduction or increase respectively, in stomatal conductance and density. Our results demonstrate that plants can balance their water uptake and loss through coordinated regulation of both stomatal and root development. PMID:27275842

  3. Balancing Water Uptake and Loss through the Coordinated Regulation of Stomatal and Root Development

    PubMed Central

    Hepworth, Christopher; Turner, Carla; Landim, Marcela Guimaraes; Cameron, Duncan; Gray, Julie E.

    2016-01-01

    Root development is influenced by nutrient and water availabilities. Plants are able to adjust many attributes of their root in response to environmental signals including the size and shape of the primary root, lateral roots and root hairs. Here we investigated the response of roots to changes in the levels of leaf transpiration associated with altered stomatal frequency. We found that plants with high stomatal density and conductance produce a larger rooting area and as a result have enhanced phosphate uptake capacity whereas plants with low stomatal conductance produce a smaller root. Manipulating the growth environment of plants indicated that enhanced root growth is most likely a result of an increased demand for water rather than phosphate. Plants manipulated to have an increase or reduction in root hair growth show a reduction or increase respectively, in stomatal conductance and density. Our results demonstrate that plants can balance their water uptake and loss through coordinated regulation of both stomatal and root development. PMID:27275842

  4. Removal of microbial biofilm on Water Hyacinth plants roots by ultrasonic treatment.

    PubMed

    Kirzhner, F; Zimmels, Y; Malkovskaja, A; Starosvetsky, J

    2009-02-01

    The capacity of floating aquatic plants to purify sewage effluents drops rapidly as a result of biofouling processes that occur on the plant roots. This is due to the high concentration of microorganisms (MO) present in the wastewater. The possibility to apply low frequency (20 kHz) in sonification was examined under laboratory conditions. The ability of US to remove MO from the roots was studied using commercially available sonicators at intensity levels ranging from 2.7 W/cm(2) to 81.4 W/cm(2), (corresponding power levels ranging from 75 W to 500 W) while varying application periods between 5 and 60 min. The results show that MO can be removed effectively (up to 98%) by exposing the Eichhornia crassipes roots to US for 5 min at the intensity level of 64.5 W/cm(2). The efficiency of the wastewater treatment increased with exposure time and power input. The study proved that the US treatment is effective in removing MO that otherwise adhere to the roots, by more then two orders of magnitude. PMID:18951602

  5. Proteomic and Biochemical Analyses of the Cotyledon and Root of Flooding-Stressed Soybean Plants

    PubMed Central

    Komatsu, Setsuko; Makino, Takahiro; Yasue, Hiroshi

    2013-01-01

    Background Flooding significantly reduces the growth and grain yield of soybean plants. Proteomic and biochemical techniques were used to determine whether the function of cotyledon and root is altered in soybean under flooding stress. Results Two-day-old soybean plants were flooded for 2 days, after which the proteins from root and cotyledon were extracted for proteomic analysis. In response to flooding stress, the abundance of 73 and 28 proteins was significantly altered in the root and cotyledon, respectively. The accumulation of only one protein, 70 kDa heat shock protein (HSP70) (Glyma17g08020.1), increased in both organs following flooding. The ratio of protein abundance of HSP70 and biophoton emission in the cotyledon was higher than those detected in the root under flooding stress. Computed tomography and elemental analyses revealed that flooding stress decreases the number of calcium oxalate crystal the cotyledon, indicating calcium ion was elevated in the cotyledon under flooding stress. Conclusion These results suggest that calcium might play one role through HSP70 in the cotyledon under flooding stress. PMID:23799004

  6. Investigation of plant water relations with divided root systems of soybean.

    PubMed

    Michel, B E; Elsharkawi, H M

    1970-11-01

    Soybean (Glycine max) was grown with root systems divided between adjacent cartons containing nutrient solution or soil. By adding polyethylene glycol (Carbowax 6000) to reduce solute potential or withholding water to reduce soil matric potential until water absorption from that side stopped, the root xylem water potential could be ascertained. Carbowax appeared to increase root resistance. An imbalance technique is described with which soil moisture contents of adjacent containers were followed individually. The patterns of water absorption obtained following repeated additions of water or addition of CaCl(2) solutions to one side indicated soil hydraulic conductivity became limiting at a soil water potential of -2 bars. A high concentration of CaCl(2) added to one side greatly reduced transpiration and produced severe plant injury. With part of the root system developing in nutrient solution, growth of roots into and water absorption from soil were slow; however, reduction of solute potential in the solution side greatly increased water absorption from the soil side. PMID:16657537

  7. Root ABA Accumulation in Long-Term Water-Stressed Plants is Sustained by Hormone Transport from Aerial Organs.

    PubMed

    Manzi, Matías; Lado, Joanna; Rodrigo, María Jesús; Zacarías, Lorenzo; Arbona, Vicent; Gómez-Cadenas, Aurelio

    2015-12-01

    The reduced pool of the ABA precursors, β,β-carotenoids, in roots does not account for the substantial increase in ABA content in response to water stress (WS) conditions, suggesting that ABA could be transported from other organs. Basipetal transport was interrupted by stem-girdling, and ABA levels were determined in roots after two cycles of WS induced by transplanting plants to dry perlite. Leaf applications of isotope-labeled ABA and reciprocal grafting of ABA-deficient tomato mutants were used to confirm the involvement of aerial organs on root ABA accumulation. Disruption of basipetal transport reduced ABA accumulation in roots, and this decrease was more severe after two consecutive WS periods. This effect was linked to a sharp decrease in the β,β-carotenoid pool in roots in response to water deficit. Significant levels of isotope-labeled ABA were transported from leaves to roots, mainly in plants subjected to water dehydration. Furthermore, the use of different ABA-deficient tomato mutants in reciprocal grafting combinations with wild-type genotypes confirmed the involvement of aerial organs in the ABA accumulation in roots. In conclusion, accumulation of ABA in roots after long-term WS periods largely relies on the aerial organs, suggesting a reduced ability of the roots to synthesize ABA from carotenoids. Furthermore, plants are able to transport ABA basipetally to sustain high hormone levels in roots. PMID:26542111

  8. Revealing crosstalk of plant and fungi in the symbiotic roots of sewage-cleaning Eichhornia crassipes using direct de novo metatranscriptomic analysis

    PubMed Central

    Luo, Bin; Gu, Wei; Zhong, Jiayong; Wang, Ying; Zhang, Gong

    2015-01-01

    Cultivation and environmental changes can induce development of novel phenotypes in plants. For example, the root morphology of cultivated purple root Eichhornia crassipes differs remarkably from normal Eichhornia crassipes and also shows an enhanced ability to absorb heavy metal from groundwater. However, the changes in gene expression associated with these processes are unknown because of the lack of information on its large and unsequenced genome and its complex plant-rhizosphere symbiotic system. To investigate these gene expression changes, we applied a new strategy, direct de novo metatranscriptome analysis. Using this approach, we assembled the metatranscriptome of the entire rhizosphere and identified species-specific differentially expressed genes (DEGs) via hyper-accurate algorithms, showing a polarized plant/fungus distribution: the plant genes were responsible for morphological changes to the root system, offering a greater volume and surface area that hosts more fungi; while genes associated with heavy metal response in the fungus Fusarium were upregulated more than 3600-fold. These results suggested a distinct and synergistic functional response by the plant and fungal transcriptomes, indicating significant plant/fungal crosstalk during environmental changes. This study demonstrates that the metatranscriptomic approach adopted here offers a cost-efficient strategy to study symbiosis systems without the need for a priori genomic knowledge. PMID:26472343

  9. Revealing crosstalk of plant and fungi in the symbiotic roots of sewage-cleaning Eichhornia crassipes using direct de novo metatranscriptomic analysis.

    PubMed

    Luo, Bin; Gu, Wei; Zhong, Jiayong; Wang, Ying; Zhang, Gong

    2015-01-01

    Cultivation and environmental changes can induce development of novel phenotypes in plants. For example, the root morphology of cultivated purple root Eichhornia crassipes differs remarkably from normal Eichhornia crassipes and also shows an enhanced ability to absorb heavy metal from groundwater. However, the changes in gene expression associated with these processes are unknown because of the lack of information on its large and unsequenced genome and its complex plant-rhizosphere symbiotic system. To investigate these gene expression changes, we applied a new strategy, direct de novo metatranscriptome analysis. Using this approach, we assembled the metatranscriptome of the entire rhizosphere and identified species-specific differentially expressed genes (DEGs) via hyper-accurate algorithms, showing a polarized plant/fungus distribution: the plant genes were responsible for morphological changes to the root system, offering a greater volume and surface area that hosts more fungi; while genes associated with heavy metal response in the fungus Fusarium were upregulated more than 3600-fold. These results suggested a distinct and synergistic functional response by the plant and fungal transcriptomes, indicating significant plant/fungal crosstalk during environmental changes. This study demonstrates that the metatranscriptomic approach adopted here offers a cost-efficient strategy to study symbiosis systems without the need for a priori genomic knowledge. PMID:26472343

  10. Biosynthesis of luminescent CdS quantum dots using plant hairy root culture

    NASA Astrophysics Data System (ADS)

    Borovaya, Mariya N.; Naumenko, Antonina P.; Matvieieva, Nadia A.; Blume, Yaroslav B.; Yemets, Alla I.

    2014-12-01

    CdS nanoparticles have a great potential for application in chemical research, bioscience and medicine. The aim of this study was to develop an efficient and environmentally-friendly method of plant-based biosynthesis of CdS quantum dots using hairy root culture of Linaria maroccana L. By incubating Linaria root extract with inorganic cadmium sulfate and sodium sulfide we synthesized stable luminescent CdS nanocrystals with absorption peaks for UV-visible spectrometry at 362 nm, 398 nm and 464 nm, and luminescent peaks at 425, 462, 500 nm. Transmission electron microscopy of produced quantum dots revealed their spherical shape with a size predominantly from 5 to 7 nm. Electron diffraction pattern confirmed the wurtzite crystalline structure of synthesized cadmium sulfide quantum dots. These results describe the first successful attempt of quantum dots synthesis using plant extract.

  11. Use of plant residues for improving soil fertility, pod nutrients, root growth and pod weight of okra (Abelmoschus esculentum L).

    PubMed

    Moyin-Jesu, Emmanuel Ibukunoluwa

    2007-08-01

    The effect of wood ash, sawdust, ground cocoa husk, spent grain and rice bran upon root development, ash content, pod yield and nutrient status and soil fertility for okra (Abelmoschus esculentum L NHAe 47 variety) was studied. The five organic fertilizer treatments were compared to chemical fertilizer (400kg/ha/crop NPK 15-15-15) and unfertilized controls in four field experiments replicated four times in a randomized complete block design. The results showed that the application of 6tha(-1) of plant residues increased (P<0.05) the soil N, P, K, Ca, Mg, pH, and SOM; pod N, P, K, Ca, Mg and ash; root length; and pod yield of okra in all four experiments relative to the control treatment. For instance, spent grain treatment increased the okra pod yield by 99%, 33%, 50%, 49%, 65% and 67% compared to control, NPK, wood ash, cocoa husk, rice bran and sawdust treatments respectively. In the stepwise regression, out of the total R(2) value of 0.83 for the soil nutrients to the pod yield of okra; soil N accounted for 50% of the soil fertility improvement and yield of okra. Spent grain, wood ash and cocoa husk were the most effective in improving okra pod weight, pod nutrients, ash content, root length and soil fertility whereas the rice bran and sawdust were the least effective. This was because the spent grain, wood ash and cocoa husk had lower C/N ratio and higher nutrient composition than rice bran and sawdust, thus, the former enhanced an increase in pod nutrients, composition for better human dietary intake, increased the root length, pod weight of okra and improved soil fertility and plant nutrition crop. The significance of the increases in okra mineral nutrition concentration by plant residues is that consumers will consume more of these minerals in their meals and monetarily spend less for purchasing vitamins and mineral supplement drugs to meet health requirements. In addition, the increase in plant nutrition and soil fertility would help to reduce the high cost

  12. In vitro thrombolytic potential of root extracts of four medicinal plants available in Bangladesh

    PubMed Central

    Hussain, Fahad; Islam, Ariful; Bulbul, Latifa; Moghal, Mizanur Rahman; Hossain, Mohammad Salim

    2014-01-01

    Context: Thrombus formation inside the blood vessels obstructs blood flow through the circulatory system leading hypertension, stroke to the heart, anoxia, and so on. Thrombolytic drugs are widely used for the management of cerebral venous sinus thrombosis patients, but they have certain limitations. Medicinal plants and their components possessing antithrombotic activity have been reported before. However, plants that could be used for thrombolysis has not been reported so far. Aims: This study's aim was to evaluate the thrombolytic potential of selected plants’ root extracts. Settings and Design: Plants were collected, dried, powdered and extracted by methanol and then fractionated by n-hexane for getting the sample root extracts. Venous blood samples were drawn from 10 healthy volunteers for the purposes of investigation. Subjects and Methods: An in vitro thrombolytic model was used to check the clot lysis potential of four n-hexane soluble roots extracts viz., Acacia nilotica, Justicia adhatoda, Azadirachta indica, and Lagerstroemia speciosa along with streptokinase as a positive control and saline water as a negative control. Statistical Analysis Used: Dunnett t-test analysis was performed using SPSS is a statistical analysis program developed by IBM Corporation, USA. on Windows. Results: Using an in vitro thrombolytic model, A. nilotica, L. speciosa, A. indica, and J. adhatoda at 5 mg extract/ml NaCl solution concentration showed 15.1%, 15.49%, 21.26%, and 19.63% clot lysis activity respectively. The reference streptokinase showed 47.21%, and 24.73% clot lysis for 30,000 IU and 15,000 IU concentrations, respectively whereas 0.9% normal saline showed 5.35% clot lysis. Conclusions: The selected extracts of the plant roots possess marked thrombolytic properties that could lyse blood clots in vitro; however, in vivo clot dissolving properties and active components responsible for clot lysis are yet to be discovered. PMID:25538351

  13. Detection of carbon nanotubes in plant roots through microwave-induced heating

    NASA Astrophysics Data System (ADS)

    Irin, Fahmida; Shrestha, Babina; Canas, Jaclyn; Saed, Mohammad; Green, Micah

    2012-02-01

    We demonstrate a novel technique for quantitative detection of CNTs in biological samples by utilizing the thermal response of CNTs under microwave irradiation. In particular, rapid heating of CNTs due to microwave absorption was employed to quantify the amount of CNTs present in alfalfa plant roots. Alfalfa roots were prepared by injecting a known amount of CNTs (single walled and multi walled) and exposed to 30-50 W microwave power to generate calibration curves (temperature rise vs. CNT mass). These calibration curves serve as a characterization tool to determine the unknown amount of CNTs absorbed by alfalfa plant roots grown in CNT-laden soil with superior accuracy and sensitivity. Moreover, the threshold for detectable CNT concentration is much lower than common analytical methods of detecting nanomaterials, such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Raman spectroscopy. Considering the lack of effective detection methods for CNT uptake in plants, this method is not only unique but also practical, as it addresses a major problem in the field of nanotoxicology risk assessment.

  14. Survival trade-offs in plant roots during colonization by closely related beneficial and pathogenic fungi.

    PubMed

    Hacquard, Stéphane; Kracher, Barbara; Hiruma, Kei; Münch, Philipp C; Garrido-Oter, Ruben; Thon, Michael R; Weimann, Aaron; Damm, Ulrike; Dallery, Jean-Félix; Hainaut, Matthieu; Henrissat, Bernard; Lespinet, Olivier; Sacristán, Soledad; Ver Loren van Themaat, Emiel; Kemen, Eric; McHardy, Alice C; Schulze-Lefert, Paul; O'Connell, Richard J

    2016-01-01

    The sessile nature of plants forced them to evolve mechanisms to prioritize their responses to simultaneous stresses, including colonization by microbes or nutrient starvation. Here, we compare the genomes of a beneficial root endophyte, Colletotrichum tofieldiae and its pathogenic relative C. incanum, and examine the transcriptomes of both fungi and their plant host Arabidopsis during phosphate starvation. Although the two species diverged only 8.8 million years ago and have similar gene arsenals, we identify genomic signatures indicative of an evolutionary transition from pathogenic to beneficial lifestyles, including a narrowed repertoire of secreted effector proteins, expanded families of chitin-binding and secondary metabolism-related proteins, and limited activation of pathogenicity-related genes in planta. We show that beneficial responses are prioritized in C. tofieldiae-colonized roots under phosphate-deficient conditions, whereas defense responses are activated under phosphate-sufficient conditions. These immune responses are retained in phosphate-starved roots colonized by pathogenic C. incanum, illustrating the ability of plants to maximize survival in response to conflicting stresses. PMID:27150427

  15. Modeling Regulation of Zinc Uptake via ZIP Transporters in Yeast and Plant Roots

    PubMed Central

    Claus, Juliane; Chavarría-Krauser, Andrés

    2012-01-01

    In yeast (Saccharomyces cerevisiae) and plant roots (Arabidopsis thaliana) zinc enters the cells via influx transporters of the ZIP family. Since zinc is both essential for cell function and toxic at high concentrations, tight regulation is essential for cell viability. We provide new insight into the underlying mechanisms, starting from a general model based on ordinary differential equations and adapting it to the specific cases of yeast and plant root cells. In yeast, zinc is transported by the transporters ZRT1 and ZRT2, which are both regulated by the zinc-responsive transcription factor ZAP1. Using biological data, parameters were estimated and analyzed, confirming the different affinities of ZRT1 and ZRT2 reported in the literature. Furthermore, our model suggests that the positive feedback in ZAP1 production has a stabilizing function at high influx rates. In plant roots, various ZIP transporters play a role in zinc uptake. Their regulation is largely unknown, but bZIP transcription factors are thought to be involved. We set up three putative models based on: an activator only, an activator with dimerization and an activator-inhibitor pair. These were fitted to measurements and analyzed. Simulations show that the activator-inhibitor model outperforms the other two in providing robust and stable homeostasis at reasonable parameter ranges. PMID:22715365

  16. Role of Swollenin, an Expansin-Like Protein from Trichoderma, in Plant Root Colonization1[W

    PubMed Central

    Brotman, Yariv; Briff, Eden; Viterbo, Ada; Chet, Ilan

    2008-01-01

    Swollenin, a protein first characterized in the saprophytic fungus Trichoderma reesei, contains an N-terminal carbohydrate-binding module family 1 domain (CBD) with cellulose-binding function and a C-terminal expansin-like domain. This protein was identified by liquid chromatography-mass spectrometry among many other cellulolytic proteins secreted in the coculture hydroponics medium of cucumber (Cucumis sativus) seedlings and Trichoderma asperellum, a well-known biocontrol agent and inducer of plant defense responses. The swollenin gene was isolated and its coding region was overexpressed in the same strain under the control of the constitutive pki1 promoter. Trichoderma transformants showed a remarkably increased ability to colonize cucumber roots within 6 h after inoculation. On the other hand, overexpressors of a truncated swollenin sequence bearing a 36-amino acid deletion of the CBD did not differ from the wild type, showing in vivo that this domain is necessary for full protein activity. Root colonization rates were reduced in transformants silenced in swollenin gene expression. A synthetic 36-mer swollenin CBD peptide was shown to be capable of stimulating local defense responses in cucumber roots and leaves and to afford local protection toward Botrytis cinerea and Pseudomonas syringae pv lachrymans infection. This indicates that the CBD domain might be recognized by the plant as a microbe-associated molecular pattern in the Trichoderma-plant interaction. PMID:18400936

  17. Survival trade-offs in plant roots during colonization by closely related beneficial and pathogenic fungi

    PubMed Central

    Hacquard, Stéphane; Kracher, Barbara; Hiruma, Kei; Münch, Philipp C.; Garrido-Oter, Ruben; Thon, Michael R.; Weimann, Aaron; Damm, Ulrike; Dallery, Jean-Félix; Hainaut, Matthieu; Henrissat, Bernard; Lespinet, Olivier; Sacristán, Soledad; Ver Loren van Themaat, Emiel; Kemen, Eric; McHardy, Alice C.; Schulze-Lefert, Paul; O'Connell, Richard J.

    2016-01-01

    The sessile nature of plants forced them to evolve mechanisms to prioritize their responses to simultaneous stresses, including colonization by microbes or nutrient starvation. Here, we compare the genomes of a beneficial root endophyte, Colletotrichum tofieldiae and its pathogenic relative C. incanum, and examine the transcriptomes of both fungi and their plant host Arabidopsis during phosphate starvation. Although the two species diverged only 8.8 million years ago and have similar gene arsenals, we identify genomic signatures indicative of an evolutionary transition from pathogenic to beneficial lifestyles, including a narrowed repertoire of secreted effector proteins, expanded families of chitin-binding and secondary metabolism-related proteins, and limited activation of pathogenicity-related genes in planta. We show that beneficial responses are prioritized in C. tofieldiae-colonized roots under phosphate-deficient conditions, whereas defense responses are activated under phosphate-sufficient conditions. These immune responses are retained in phosphate-starved roots colonized by pathogenic C. incanum, illustrating the ability of plants to maximize survival in response to conflicting stresses. PMID:27150427

  18. Enhancement of drought stress tolerance in crops by plant growth promoting rhizobacteria.

    PubMed

    Vurukonda, Sai Shiva Krishna Prasad; Vardharajula, Sandhya; Shrivastava, Manjari; SkZ, Ali

    2016-03-01

    Drought is one of the major constraints on agricultural productivity worldwide and is likely to further increase. Several adaptations and mitigation strategies are required to cope with drought stress. Plant growth promoting rhizobacteria (PGPR) could play a significant role in alleviation of drought stress in plants. These beneficial microorganisms colonize the rhizosphere/endo-rhizosphere of plants and impart drought tolerance by producing exopolysaccharides (EPS), phytohormones, 1-aminocyclopropane- 1-carboxylate (ACC) deaminase, volatile compounds, inducing accumulation of osmolytes, antioxidants, upregulation or down regulation of stress responsive genes and alteration in root morphology in acquisition of drought tolerance. The term Induced Systemic Tolerance (IST) was coined for physical and chemical changes induced by microorganisms in plants which results in enhanced tolerance to drought stresses. In the present review we elaborate on the role of PGPR in helping plants to cope with drought stress. PMID:26856449

  19. Control of in vitro rooting and plant development in Corymbia maculata by silver nitrate, silver thiosulfate and thiosulfate ion.

    PubMed

    Steinitz, Benjamin; Barr, Nurit; Tabib, Yona; Vaknin, Yiftach; Bernstein, Nirit

    2010-11-01

    Plant regeneration and transformation in vitro is often improved by adding silver ion (Ag(+)) to the culture media as AgNO(3) or silver thiosulfate (STS). Ag(+) reacts with substances to form insoluble precipitates, while thiosulfate (S(2)O(3) (2-)) interferes with these reactions. We studied the implications of silver precipitation and S(2)O(3) (2-) in the medium for culture development by (1) examining formation of Ag(+) precipitates from AgNO(3) versus STS in agar gels and their possible dependence on agar type; (2) comparing Corymbia maculata culture responses to AgNO(3) and STS and determining which better suits control of culture development; (3) clarifying whether STS-dependent alterations in culture development are due to Ag(+) alone or also to a separate influence of S(2)O(3) (2-). Silver precipitates appeared in aqueous gels of four agar brands supplemented with AgNO(3), but not in Phytagel(™), which remained transparent. No precipitation was observed in gels with STS. Indole-3-butyric acid (IBA)-mediated adventitious root induction and shoot growth were higher in C. maculata shoot tips cultured on gels with STS versus AgNO(3) (6-25 μM Ag(+)). IBA-treated shoot tips exhibited enhanced adventitious root regeneration, accelerated root elongation, increased frequency of lateral root formation, and stimulated shoot growth mediated by 100-250 μM sodium thiosulfate (Na(2)S(2)O(3)) in medium without Ag(+). The potency of S(2)O(3) (2-) in facilitating culture development has never been recognized. It is inferred that superiority of STS in stimulating multiple responses of C. maculata culture results from sustained biological activity of Ag(+) through prevention of its precipitation, and from impact of S(2)O(3) (2-) on cell differentiation and growth. PMID:20838999

  20. Msp40 effector of root-knot nematode manipulates plant immunity to facilitate parasitism

    PubMed Central

    Niu, Junhai; Liu, Pei; Liu, Qian; Chen, Changlong; Guo, Quanxin; Yin, Junmei; Yang, Guangsui; Jian, Heng

    2016-01-01

    Root-knot nematodes (RKNs) are obligate biotrophic parasites that invade plant roots and engage in prolonged and intimate relationships with their hosts. Nematode secretions, some of which have immunosuppressing activity, play essential roles in successful parasitism; however, their mechanisms of action remain largely unknown. Here, we show that the RKN-specific gene MiMsp40, cloned from Meloidogyne incognita, is expressed exclusively in subventral oesophageal gland cells and is strongly upregulated during early parasitic stages. Arabidopsis plants overexpressing MiMsp40 were more susceptible to nematode infection than were wild type plants. Conversely, the host-derived MiMsp40 RNAi suppressed nematode parasitism and/or reproduction. Moreover, overexpression of MiMsp40 in plants suppressed the deposition of callose and the expression of marker genes for bacterial elicitor elf18-triggered im