Sexually-dimorphic proteomic responses of Frankliniella occidentalis salivary glands to tomato spotted wilt virus infection

Frankliniella occidentalis, the western flower thrips, is an efficient vector of orthotospoviruses, plant viruses that infect a wide range of food, fiber and ornamental crops worldwide. Tomato spotted wilt virus (TSWV) is transmitted by thrips in a circulative-propagative manner whereby the virus infects, replicates, and disseminates from the larval midgut to the salivary gland (SG) tissues of the thrips vector as the vector develops to adulthood.  Male and female thrips exhibit sexual dimorphic feeding behavior and TSWV transmission rates. Our study tests the hypothesis that TSWV infection of adult thrips SGs modulates the abundance and/or composition of proteins secreted by the adult thrips during feeding, and these modifications affect thrips-plant host interactions. We identified a total of 2664 proteins from the SGs of both male and female thrips using nano LC-MS/MS proteomics. Among these, 22% and 23% proteins were enriched in male and female SGs, respectively. The effect of TSWV infection on the SG proteome was subtle with 2.5% (males) and 0.9% (female) of proteins differentially abundant in response to virus. Remarkably, only one differentially-abundant protein was shared between the sexes. Proteins with increased abundance in the infected male SGs have provisional gene ontologies of nucleic acid binding, protein transport and protein synthesis, whereas in the infected female SGs, ontologies implicated RNA binding and immune response.  To further test our hypothesis, proteomics will be performed on the saliva of male and female thrips infected with TSWV, and functional analysis of SG candidates with respect to thrips-plant interactions are under way.