description
- Trichoderma species are ubiquitous soil saprotrophs utilized in agriculture for their biocontrol activities. Some strains additionally possess the ability to activate induced systemic resistance (ISR) to a broad range of pathogens. Other strains have been shown to stimulate plant growth through the production of plant-growth-promoting (PGP) compounds, although both traits are rarely found together. This project focuses upon a novel, free-living, strain of T. hamatum, which exhibits biocontrol and plant growth promotion (PGP) capabilities in both monocots and dicots, controls plant diseases caused by pre- and post-emergence pathogens, can induce systemic resistance and modify root architecture, even in species where no increase in canopy development is evident (e.g. maize & wheat). As with other biocontrol/PGP solutions, field application presents many challenges. Complex cross-talk occurs during beneficial rhizosphere interactions and is influenced by the climate, soil type, time of year and host genotype, e.g. in tomato-T. atroviride and T. harzianum interactions. Therefore, there is significant added value in studies that seek to understand and exploit the chemical ecology that underpins beneficial traits conferred by Trichoderma in the rhizosphere. This project will use an interdisciplinary approach to elucidate the novel bioactive chemistry produced by T. hamatum that contributes to these agronomically important traits. Bioassay-guided fractionation (using advanced chromatographic/spectroscopic analysis i.e. MS and NMR) will be used to identify bioactive natural products from microcosm extracts of Trichoderma hamatum that provide protection of lettuce (Lactuca sativa) or brassicas against the soil pathogen Sclerotinia sclerotorium (Ss). In-soil capture of the identified chemical signals, from Trichoderma isolates and the host plants will be carried out by the insertion of reverse-phase coated fibres into Trichoderma-amended soil environment of plants, in the presence or absence of Ss, and then elution/analysis of the captured compounds. This technique will shed light on the identity of the causal metabolites involved in potential enhancement of root defence against herbivores eg. clover root weevils, Sitona lepidus. This interdisciplinary project will provide training in aspects of natural product chemistry, chemical ecology and microbiology. It will be based in Rothamsted in the lab of MB, where training in biological chemistry methods including bioassay-guided fractionation and analysis will be provided. The first year rotation will be based in MG's lab in Exeter. The candidate will train in generating microcosms, preparation of extracts with antibiotic activity from wild-type and mutant T. hamatum and undertake biological assays to evaluate Ss (or other pathogen) performance in a background of extracts, fractions and compounds.