Plant Root Exudate Analysis

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.

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

10.1101/652321 ◽

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.

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Transformation of Ag ions into Ag nanoparticle-loaded AgCl microcubes in the plant root zone

Environmental Science Nano ◽

10.1039/c9en00088g ◽

2019 ◽

Vol 6 (4) ◽

pp. 1099-1110 ◽

Cited By ~ 5

Author(s):

Huiyuan Guo ◽

Chuanxin Ma ◽

Lauren Thistle ◽

My Huynh ◽

Chenghao Yu ◽

...

Keyword(s):

Silver Nanoparticles ◽

Root Exudate ◽

Root Zone ◽

Silver Chloride ◽

Plant Root ◽

Silver Ions ◽

Ag Nanoparticle ◽

Plant Root Exudate

Silver ions can be naturally transformed into silver nanoparticles due to the plant root exudate-mediated photoreduction of silver chloride microcubes.

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

Parasitology ◽

10.1017/s0031182000059394 ◽

1991 ◽

Vol 103 (1) ◽

pp. 149-155 ◽

Cited By ~ 18

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.

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Rhizosphere interactions: root exudates, microbes, and microbial communities

Botany ◽

10.1139/cjb-2013-0225 ◽

2014 ◽

Vol 92 (4) ◽

pp. 267-275 ◽

Cited By ~ 245

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.

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

Planta ◽

10.1007/s00425-021-03766-2 ◽

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.

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

Journal of Fungi ◽

10.3390/jof7020148 ◽

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.

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