Rhizosphere interactions: root exudates, microbes, and microbial communities

Botany ◽  
2014 ◽  
Vol 92 (4) ◽  
pp. 267-275 ◽  
Author(s):  
Xing-Feng Huang ◽  
Jacqueline M. Chaparro ◽  
Kenneth F. Reardon ◽  
Ruifu Zhang ◽  
Qirong Shen ◽  
...  
Keyword(s):  
Microbial Communities ◽  
Root Exudates ◽  
Root Exudate ◽  
Management Practices ◽  
Plant Root ◽  
Agricultural Practices ◽  
Rhizosphere Interactions ◽  
Broad Variety ◽  
Sustainable Agricultural Practices ◽  
Made In

The study of the interactions between plants and their microbial communities in the rhizosphere is important for developing sustainable management practices and agricultural products such as biofertilizers and biopesticides. Plant roots release a broad variety of chemical compounds to attract and select microorganisms in the rhizosphere. In turn, these plant-associated microorganisms, via different mechanisms, influence plant health and growth. In this review, we summarize recent progress made in unraveling the interactions between plants and rhizosphere microbes through plant root exudates, focusing on how root exudate compounds mediate rhizospheric interactions both at the plant–microbe and plant–microbiome levels. We also discuss the potential of root exudates for harnessing rhizospheric interactions with microbes that could lead to sustainable agricultural practices.

Increasing the Productivity and Profitability of Paddy through Front Line Demonstrations in Irrigated Agro Ecosystem of Kaymore Platue and Satpura Hills

2016 ◽  
Vol 3 (3) ◽  
Author(s):  
DHANANJAI SINGH ◽  
A.K. PATEL ◽  
S.K. SINGH ◽  
M.S. BAGHEL
Keyword(s):  
Management Practices ◽  
Agricultural Practices ◽  
Cost Ratio ◽  
Scientific Practices ◽  
Economic Returns ◽  
Front Line ◽  
Yield Increase ◽  
Benefit Cost Ratio ◽  
Sustainable Agricultural Practices ◽  
Improved Technology

Krishi Vigyan Kendra laid down Front Line Demonstration in the year 2010-11 and 2011-12 introducing new, high yielding and scented variety “Pusa Sugandha-3” and applying scientific practices in their cultivation. The FLDs were carried out in village “Dainiha” of Sidhi district in supervision of KVK scientist. The productivity and economic returns of paddy in improved technologies were calculated and compared with the corresponding farmer's practices (local check). Improved practices recorded higher yield as compared to farmer's practices. The improved technology recorded higher yield of 30.83 q/ha and 32.65 q/ha in the year 2010-11 and 2011-12, respectively than 22.13 and 24.21 q/ha. The average yield increase was observed 37.15 per cent. In spite of increase in yield of paddy, technology gap, extension gap and technology index existed. The improved technology gave higher gross return (37020 and 39180 Rs./ha), net return (16820 and 18920 Rs./ha) with higher benefit cost ratio (1.83 and 1.93) as compared to farmer's practices. The variation in per cent increase in the yield was found due to the poor management practices, lack of knowledge and poor socio economic condition. Under sustainable agricultural practices, with this study it is concluded that the FLDs programmes were effective in changing attitude, skill and knowledge of improved package and practices of HYV of paddy adoption.

scholarly journals Implications of Climate Change on Soil Functions: A Case for Achieving Local Coconut Sufficiency from Sustainable Agricultural Practices

2021 ◽  
Author(s):  
Chinedu Egbunike ◽  
Nonso Okoye ◽  
Okoroji-Nma Okechukwu
Keyword(s):  
Climate Change ◽  
Management Practices ◽  
Negative Impact ◽  
Agricultural Practices ◽  
Sub Saharan Africa ◽  
Soil Functions ◽  
Soil Biodiversity ◽  
Environmental Consequences ◽  
Sub Saharan ◽  
Sustainable Agricultural Practices

Climate change is a major threat to agricultural food production globally and locally. It poses both direct and indirect effects on soil functions. Thus, agricultural management practices has evolved to adaptation strategies in order to mitigate the risks and threats from climate change. The study concludes with a recommendation the coconut farmers should explore the idea of soil biodiversity in a bid to mitigate the potential negative impact of climate related risk on the farming. The study proffers the need for adopting sustainable agricultural practices to boost local coconut production. This can contribute to the simultaneous realisation of two of the Sustainable Development Goals (SDGs) of the United Nations: SDG 2 on food security and sustainable agriculture and SDG 13 on action to combat climate change and its impacts. The study findings has implications for tackling climate change in Sub-Saharan Africa and in particular Nigeria in order to boost local agricultural production and coconut in particular without negative environmental consequences and an ability to cope with climate change related risks.

In vitro studies on the behaviour of second-stage juveniles of Heterodera schachtii (Nematoda: Heteroderidae) in response to host plant root exudates

Parasitology ◽  
1991 ◽  
Vol 103 (1) ◽  
pp. 149-155 ◽  
Author(s):  
F. Grundler ◽  
L. Schnibbe ◽  
U. Wyss
Keyword(s):  
Root Exudates ◽  
Root Exudate ◽  
Plant Root ◽  
Time Lapse ◽  
Heterodera Schachtii ◽  
Second Stage ◽  
Video Recordings ◽  
Aseptic Conditions ◽  
Agarose Layer

The behaviour of Heterodera schachtii second-stage juveniles in response to mustard (Sinapis alba) rooxudates was observed and analysed under aseptic conditions in a standardized bioassay. Aggregation of juveniles on an agarose layer occurred within less than 30 min in the area where root exudates had been applied and persisted for several hours. Analysis of time-lapse video recordings showed that the aggregation did not result from a directed orientation of the juvenile towards the root exudate. This was supported by an orientation assay using single juveniles. Aggregated juveniles showed pre-infection exploratory behaviour, including stylet thrusting and head-end bending, while staying at rest for several minutes.

scholarly journals Barriers and Facilitators for Adopting Sustainable Soil Management Practices in Mediterranean Olive Groves

Agronomy ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 506 ◽  
Author(s):  
José A. Aznar-Sánchez ◽  
Juan F. Velasco-Muñoz ◽  
Belén López-Felices ◽  
Fernando del Moral-Torres
Keyword(s):  
Agricultural Soil ◽  
Management Practices ◽  
Carbon Sink ◽  
Organic Matter Content ◽  
Agricultural Practices ◽  
Soil Management ◽  
Matter Content ◽  
Sustainable Practices ◽  
Sustainable Soil Management ◽  
Sustainable Agricultural Practices

Soil is a fundamental resource, subject to severe and quick degradation processes because of the pressure of human activities, particularly in many regions of the Mediterranean where agriculture is an important economic activity. It has been proven that the use of sustainable soil management practices can potentially give rise to the creation of a carbon sink, an increase of soil organic matter content, the maintenance of crop productivity and a reduction in erosion. Despite the existence of scientific evidence about the benefits generated by the use of sustainable practices on soil, many farmers are reluctant to adopt them. The objective of this study is to identify and give a hierarchical structure to the factors that condition the adoption of sustainable practices in the management of agricultural soil. The case of olive tree cultivation in Southeast Spain has been studied, using a participatory qualitative methodology. The results show a series of seven principal barriers (information, costs, risk aversion, characteristics of the farm and sustainable practices, macro factors, and cultural barriers) and five facilitators (technology, farmer training, awareness, incentives, and social pressure) for the adoption of the proposed sustainable agricultural practices. The principal political and legislative actions proposed to increase the adoption of sustainable agricultural practices include: administrative control, fostering environmental awareness, technical knowledge, and on-farm demonstrations; and, on the economic and financial level, incorporation of both general incentives and subsidizing specific costs. This study contributes to the development and discussion of intervention proposals that are designed to stimulate the implementation of sustainable practices in agricultural soil management.

Inverse method to estimate mineralisation rate constants for nitrogen simulation models: interaction between sampling strategy and quality of parameter estimates

Soil Research ◽  
1998 ◽  
Vol 36 (1) ◽  
pp. 1 ◽  
Author(s):  
V. O. Snow ◽  
W. J. Bond
Keyword(s):  
Management Practices ◽  
Agricultural Practices ◽  
Sampling Strategy ◽  
Simulation Models ◽  
Simulation Modelling ◽  
Land Application ◽  
Parameter Estimates ◽  
Concentration Data ◽  
Data Set ◽  
Sustainable Agricultural Practices

Sustainable agricultural practices and land application of wastes require that the accession of nitrate to groundwater be within acceptable limits. Simulation modelling is a valuable aid to the development and testing of management practices that achieve this goal, but requires unbiased and precise parameter estimates. Here we consider the role of simple lysimeter-based techniques, which may yield only a single integral observation in the form of total solute leached or total drainage, in supplementing infrequent concentration data for the purposes of parameter optimisation. The utility of such techniques was evaluated using a simulation model to create a ‘no-error data set’ of nitrate concentration values and summary observations of the total mass of nitrate leached and total drainage over a 182-day period. From that no-error data set a more realistic data set incorporating random error was created. By using those concentrations, the value of the mass of nitrate leached or total drainage was evaluated by their effect on the unbias and precision of optimised mineralisation or evaporation parameters. The effects of observation weight, error in the observations, and 2 other experimental strategies involving a higher intensity of solute sampling were also tested. It was found that the summary observations, such as those obtainable from simple lysimeter-based techniques, had the potential to reduce bias and improve the precision of the optimised parameters. The consequence of this effectiveness was that error in the summary observations led to considerable error in the optimised parameters.

scholarly journals UPLC-MS/MS analysis and biological activity of the potato cyst nematode hatching stimulant, solanoeclepin A, in the root exudate of Solanum spp.

Planta ◽  
2021 ◽  
Vol 254 (6) ◽  
Author(s):  
Alessandra Guerrieri ◽  
Kristýna Floková ◽  
Lieke E. Vlaar ◽  
Mario L. Schilder ◽  
Gertjan Kramer ◽  
...  
Keyword(s):  
Root Exudates ◽  
Analytical Method ◽  
Natural Variation ◽  
Root Exudate ◽  
Plant Root ◽  
Cyst Nematode ◽  
Potato Cyst Nematode ◽  
Globodera Pallida ◽  
Solanaceous Species ◽  
Highly Sensitive

Abstract Main conclusion Solanoeclepin A is a hatching stimulant for potato cyst nematode in very low (pM) concentrations. We report a highly sensitive method for the analysis of SolA in plant root exudates using UHPLC-MS/MS and show that there is considerable natural variation in SolA production in Solanum spp. corresponding with their hatching inducing activity. Abstract Potato cyst nematode (PCN) is a plant root sedentary endoparasite, specialized in the infection of solanaceous species such as potato (Solanum tuberosum) and tomato (Solanum lycopersicum). Earlier reports (Mulder et al. in Hatching agent for the potato cyst nematode, Patent application No. PCT/NL92/00126, 1996; Schenk et al. in Croat Chem Acta 72:593–606, 1999) showed that solanoeclepin A (SolA), a triterpenoid metabolite that was isolated from the root exudate of potato, induces the hatching of PCN. Its low concentration in potato root exudate has hindered progress in fully understanding its hatching inducing activity and exploitation in the control of PCN. To further investigate the role of SolA in hatching of PCN, the establishment of a highly sensitive analytical method is a prerequisite. Here we present the efficient single-step extraction and UHPLC-MS/MS based analysis for rapid determination of SolA in sub-nanomolar concentrations in tomato root exudate. This method was used to analyze SolA production in different tomato cultivars and related solanaceous species, including the trap crop Solanum sisymbriifolium. Hatching assays with PCN, Globodera pallida, with root exudates of tomato genotypes revealed a significant positive correlation between SolA concentration and hatching activity. Our results demonstrate that there is natural variation in SolA production within solanaceous species and that this has an effect on PCN hatching. The analytical method we have developed can potentially be used to support breeding for crop genotypes that induce less hatching and may therefore display reduced infection by PCN.

scholarly journals Comparison of Plant Metabolites in Root Exudates of Lolium perenne Infected with Different Strains of the Fungal Endophyte Epichloë festucae var. lolii

2021 ◽  
Vol 7 (2) ◽  
pp. 148
Author(s):  
Aurora Patchett ◽  
Jonathan A. Newman
Keyword(s):  
Lolium Perenne ◽  
Root Exudates ◽  
Root Exudate ◽  
Plant Biomass ◽  
Insect Pests ◽  
Plant Root ◽  
Fungal Endophyte ◽  
Plant Metabolites ◽  
Primary And Secondary Metabolites ◽  
Epichloë Festucae

Lolium perenne infected with the fungal endophyte Epichloë festucae var. lolii have specific, endophyte strain-dependent, chemical phenotypes in their above-ground tissues. Differences in these chemical phenotypes have been largely associated with classes of fungal-derived alkaloids which protect the plant against many insect pests. However, the use of new methodologies, such as various omic techniques, has demonstrated that many other chemical changes occur in both primary and secondary metabolites. Few studies have investigated changes in plant metabolites exiting the plant in the form of root exudates. As root exudates play an essential role in the acquisition of nutrients, microbial associations, and defense in the below-ground environment, it is of interest to understand how plant root exudate chemistry is influenced by the presence of strains of a fungal endophyte. In this study, we tested the influence of four strains of E. festucae var. lolii (E+ (also known as Lp19), AR1, AR37, NEA2), and uninfected controls (E−), on L. perenne growth and the composition of root exudate metabolites. Root exudates present in the hydroponic water were assessed by untargeted metabolomics using Accurate-Mass Quadrupole Time-of-Flight (Q–TOF) liquid chromatography–mass spectrometry (LC–MS). The NEA2 endophyte strain resulted in the greatest plant biomass and the lowest endophyte concentration. We found 84 metabolites that were differentially expressed in at least one of the endophyte treatments compared to E− plants. Two compounds were strongly associated with one endophyte treatment, one in AR37 (m/z 135.0546 RT 1.17), and one in E+ (m/z 517.1987 RT 9.26). These results provide evidence for important changes in L. perenne physiology in the presence of different fungal endophyte strains. Further research should aim to connect changes in root exudate chemical composition with soil ecosystem processes.

scholarly journals ABC transporter genes ABC-C6 and ABC-G33 alter plant-microbe-parasite interactions in the rhizosphere

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Deborah Elizabeth Cox ◽  
Steven Dyer ◽  
Ryan Weir ◽  
Xavier Cheseto ◽  
Matthew Sturrock ◽  
...  
Keyword(s):  
Abc Transporter ◽  
Root Exudates ◽  
Root Exudate ◽  
Plant Root ◽  
Crop Improvement ◽  
Crop Protection ◽  
Egg Hatching ◽  
Plant Root Exudate ◽  
Wide Range ◽  
Abc Transporter Genes

AbstractPlants are master regulators of rhizosphere ecology, secreting a complex mixture of compounds into the soil, collectively termed plant root exudate. Root exudate composition is highly dynamic and functional, mediating economically important interactions between plants and a wide range of soil organisms. Currently we know very little about the molecular basis of root exudate composition, which is a key hurdle to functional exploitation of root exudates for crop improvement. Root expressed transporters modulate exudate composition and could be manipulated to develop beneficial plant root exudate traits. Using Virus Induced Gene silencing (VIGS), we demonstrate that knockdown of two root-expressed ABC transporter genes in tomato cv. Moneymaker, ABC-C6 and ABC-G33, alters the composition of semi-volatile compounds in collected root exudates. Root exudate chemotaxis assays demonstrate that knockdown of each transporter gene triggers the repulsion of economically relevant Meloidogyne and Globodera spp. plant parasitic nematodes, which are attracted to control treatment root exudates. Knockdown of ABC-C6 inhibits egg hatching of Meloidogyne and Globodera spp., relative to controls. Knockdown of ABC-G33 has no impact on egg hatching of Meloidogyne spp. but has a substantial inhibitory impact on egg hatching of G. pallida. ABC-C6 knockdown has no impact on the attraction of the plant pathogen Agrobacterium tumefaciens, or the plant growth promoting Bacillus subtilis, relative to controls. Silencing ABC-G33 induces a statistically significant reduction in attraction of B. subtilis, with no impact on attraction of A. tumefaciens. By inoculating selected differentially exuded compounds into control root exudates, we demonstrate that hexadecaonic acid and pentadecane are biologically relevant parasite repellents. ABC-C6 represents a promising target for breeding or biotechnology intervention strategies as gene knockdown leads to the repulsion of economically important plant parasites and retains attraction of the beneficial rhizobacterium B. subtilis. This study exposes the link between ABC transporters, root exudate composition, and ex planta interactions with agriculturally and economically relevant rhizosphere organisms, paving the way for new approaches to rhizosphere engineering and crop protection.

scholarly journals ETHYLENE RESPONSE FACTOR (ERF) genes modulate plant root exudate composition and the attraction of plant parasitic nematodes

2019 ◽  
Author(s):  
Steven Dyer ◽  
Ryan T Weir ◽  
Deborah Cox ◽  
Xavier Cheseto ◽  
Baldwyn Torto ◽  
...  
Keyword(s):  
Root Exudates ◽  
Root Exudate ◽  
Plant Root ◽  
Parasitic Nematodes ◽  
Ethylene Response Factor ◽  
Response Factor ◽  
Plant Parasitic Nematodes ◽  
Ethylene Response ◽  
Plant Root Exudate ◽  
Plant Parasitic

Plant root exudates are compositionally diverse, plastic and adaptive. Ethylene signalling influences the attraction of plant parasitic nematodes (PPNs), presumably through the modulation of root exudate composition. Understanding this pathway could lead to new sources of crop parasite resistance. Here we have used Virus-Induced Gene Silencing (VIGS) to knockdown the expression of two ETHYLENE RESPONSE FACTOR (ERF) genes, ERF-E2 and ERF-E3 in tomato. Root exudates are significantly more attractive to the PPNs Meloidogyne incognita, and Globodera pallida following knockdown of ERF-E2, which has no impact on the attraction of Meloidogyne javanica. Knockdown of ERF-E3 has no impact on the attraction of Meloidogyne or Globodera spp. GC-MS analysis revealed substantial changes in root exudate composition relative to controls. However, these changes do not alter the attraction of rhizosphere microbes Bacillus subtilis or Agrobacterium tumefaciens. This study further supports the potential of engineering plant root exudate for parasite control, through the modulation of plant genes.

scholarly journals Specific Root Exudate Compounds Sensed by Dedicated Chemoreceptors Shape Azospirillum brasilense Chemotaxis in the Rhizosphere

2020 ◽  
Vol 86 (15) ◽  
Author(s):  
Lindsey O’Neal ◽  
Lam Vo ◽  
Gladys Alexandre
Keyword(s):  
Root Exudates ◽  
Root Exudate ◽  
Plant Root ◽  
Bacterial Chemotaxis ◽  
Root Surface ◽  
Content Type ◽  
Surface Colonization ◽  
Motile Cells ◽  
Microbe Interactions ◽  
Root Surfaces

ABSTRACT Plant roots shape the rhizosphere community by secreting compounds that recruit diverse bacteria. Colonization of various plant roots by the motile alphaproteobacterium Azospirillum brasilense causes increased plant growth, root volume, and crop yield. Bacterial chemotaxis in this and other motile soil bacteria is critical for competitive colonization of the root surfaces. The role of chemotaxis in root surface colonization has previously been established by endpoint analyses of bacterial colonization levels detected a few hours to days after inoculation. More recently, microfluidic devices have been used to study plant-microbe interactions, but these devices are size limited. Here, we use a novel slide-in chamber that allows real-time monitoring of plant-microbe interactions using agriculturally relevant seedlings to characterize how bacterial chemotaxis mediates plant root surface colonization during the association of A. brasilense with Triticum aestivum (wheat) and Medicago sativa (alfalfa) seedlings. We track A. brasilense accumulation in the rhizosphere and on the root surfaces of wheat and alfalfa. A. brasilense motile cells display distinct chemotaxis behaviors in different regions of the roots, including attractant and repellent responses that ultimately drive surface colonization patterns. We also combine these observations with real-time analyses of behaviors of wild-type and mutant strains to link chemotaxis responses to distinct chemicals identified in root exudates to specific chemoreceptors that together explain the chemotactic response of motile cells in different regions of the roots. Furthermore, the bacterial second messenger c-di-GMP modulates these chemotaxis responses. Together, these findings illustrate dynamic bacterial chemotaxis responses to rhizosphere gradients that guide root surface colonization. IMPORTANCE Plant root exudates play critical roles in shaping rhizosphere microbial communities, and the ability of motile bacteria to respond to these gradients mediates competitive colonization of root surfaces. Root exudates are complex chemical mixtures that are spatially and temporally dynamic. Identifying the exact chemical(s) that mediates the recruitment of soil bacteria to specific regions of the roots is thus challenging. Here, we connect patterns of bacterial chemotaxis responses and sensing by chemoreceptors to chemicals found in root exudate gradients and identify key chemical signals that shape root surface colonization in different plants and regions of the roots.

Sign in / Sign up

Export Citation Format

Share Document