Primed for parasitism: pathogenic nematodes tailor their response to host plant exudates

Background
Plant-parasitic nematodes are important agricultural pests that have complex interactions with their host. Many of the most damaging species have extremely wide host ranges, whilst others are restricted to a single genus of plants. However, surprisingly little is known about the molecular mechanisms that initiate parasitism and underpin host preference and differential host success. We have shown that host-specific gene expression patterns are induced in a plant-parasitic nematode
when it detects particular components of host root exudates. Consequently, expression of genes important for parasitism is tailored to the identity of the immediate host root. Our hypothesis is that this transcriptional plasticity may contribute to polyphagy.
Objectives
-Explore the extent of "primed" gene expression in plant-parasitic nematodes and how this varies with plant identity
-Determine the components of root exudate responsible for priming
-Establish the effect of mycorrhizal colonisation on root exudate-induced nematode gene expression and subsequent parasitic success
Novelty and Timeliness
Differential gene expression in response to different hosts has not previously been observed for plant parasitic nematodes. The effect of this transcriptional plasticity on nematode host range is unknown.
The project will capitalise on BBSRC funding for plant-parasitic nematode genomics and build on new collaborative research between Urwin and Field.
Experimental approach
RNAseq will establish the array of genes induced in plant-parasitic nematodes with contrasting host ranges upon exposure to root exudates from both hosts and non-hosts. Selected genes will be characterized further by qRT-PCR, in situ hybridization and RNAi to determine their importance in parasitism. Expression in response to mycorrhizal colonized roots will be compared.
In all cases, biochemical/metabolomic analysis of root exudates will determine differences in eg. sugars, amino acids, cell wall components that may underlie nematode responses. Use of over-expression/mutant/CRISPR plants will confirm a role for these components.