Using viral gene products to disrupt insect-plant interactions and inhibit virus transmission

Recent work in the Carr lab (Westwood et al. 2013, 2014) and in other labs (e.g. Casteel et al. 2014) indicates that expression of different virally-coded proteins in transgenic Arabidopsis and other model plants can alter the interactions of plants with aphids. This is important because most plant viruses are transmitted by insects, with aphids being the predominant group of vectors. Curiously, expression of viral factors (or viral infection itself) can either induce resistance to aphids or susceptibility (the epidemiological implications of this are explored in Westwood et al. 2013). Understanding how these viral factors act could offer an opportunity to develop new methods of control against these important insect pests, which are also important disease vectors. This project will explore the mechanisms (changes in gene expression, biosynthesis of low molecular weight compounds) through which these viral proteins alter plant aphid interactions. Using Arabidopsis mutants transformed to express specific viral proteins (from aphid-transmitted and other viruses: see Westwood et al. 2014) the project will explore how these viral factors elicit resistance or susceptibility to aphid infestation. For example, do these factors work by altering defensive pathways involving the important signal chemicals jasmonic acid or salicylic acid (Lewsey et al. 2010; Westwood et al. 2014; Zhou et al. 2014)? Alternatively, do they act through disruption of upstream signalling in effector- or PAMP-triggered immunity responses (Clay et al. 2009; Macho and Zipfel 2014; Westwood et al 2013)? Additional avenues of research (depending on the interests of the student and time available) will investigate the changes in volatile signals (analyzed by GC-MS) emitted by plants that affect attractiveness versus repulsion when a viral gene product is present and the effects of these changes on the efficiency of virus transmission by aphids. The work is integrated into a wider program, which includes collaboration with partners in east Africa investigating the effect of virus infection on aphid-mediated transmission of viruses in crops (see 'Leaving a 'bad taste in aphids' mouths' at http://www.bbsrc.ac.uk/web/FILES/Publications/1210-scprid.pdf).