Plants and microbes have co-evolved over millions of years. Root exudates play an important role in this interaction by influencing the soil microbiome, especially the rhizobiome (those microbes that are closely associated with roots). In turn, plants themselves are influenced by soil microbes, impacting their growth, development, physiology and responses to stress. Beneficial soil microbes can protect plants against soil-borne pathogens via direct antagonism, including competition for space and nutrients or synthesising antimicrobial compounds. They can also offer indirect protection by priming the plant immune system via induced systemic resistance (ISR), enabling plants to mount a stronger immune response to biotic stress. Recent evidence has shown that pathogen-infected plants change their root exudation chemistry to select and/or recruit disease-suppressive soil microbes. This so-called ‘cry-for-help’ has long-lasting effects that can even benefit plants of the next generation.
In this project you will explore how agricultural practice influences the interactions between plants, soil and root exudates, with the aim of understanding the mechanisms that lead to disease suppression. You will test the hypothesis that in organic and regenerative agriculture, improved soil structure and increased soil microbial diversity facilitate plant-exudate-microbe interactions that lead to disease suppression. You will undertake field surveys to identify soils, or individual plants, where disease symptoms are reduced or absent, focussing on soil-borne phytopathogens of crops, as these are agronomically and economically important. We hypothesise that, in some cases, reduced disease incidence results from the presence of disease-suppressive soils.
You will take an interdisciplinary approach to study these interactions. You will determine the physical structure of the soil using X-ray computerised tomography. A combination of rhizobiome transplantation experiments, plant phenotyping for disease, high-throughput metabolomics, DNA sequencing and culturing will be used identify factors that lead to the generation of disease suppression. Metabolomic analysis will be used to identify the signalling metabolites in root exudates of diseased plants that select/recruit beneficial microbes, as well as antimicrobial molecules causing suppression or having cidal effects. You will also measure plant gene expression to determine the ability of microbes to elicit ISR against a range of root or foliar diseases. These factors will be tested in soils of different structures to determine the impact of soil structure on disease suppression. Selected microbes or metabolites will be tested as seed coatings during an industrial placement with Syngenta. This will allow you to develop durable in-field resistance strategies against important crop diseases.
The project will you with training in advanced ‘omic techniques and their application to agriculture. This is a highly interdisciplinary project that explores how we can improve crop sustainability by increasing resilience to biotic stresses whilst preserving soil and reducing the need for agrochemical inputs.
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