Glassy Winged Sharpshooter Insect Genome Footprints Through Transcriptomic and Small RNA Sequence Profiling

Glassy winged sharp shooter (GWSS) insects are xylem-feeding leafhoppers that have a broad host range and are of major economic concern due to their ability to spread the bacterium, Xylella fastidiosa, the causal agent of Pierce’s Disease of grapevines. We have generated transcriptomic and small RNA profiling sequences of GWSS adult stage insects, the analysis of which helped us in the identification of specific host RNAi targets and two GWSS-infecting viruses of significance, Homalodisca coagulata 1 (HoCV-1) and Homalodisca reovirus (HoVRV). Specifically several GWSS gut genes were identified and verified through RT-PCR studies. We were able to use the generated genome information to develop transgenic plants for GWSS RNAi targets such as GWSS-actin and GWSS-cuticle in Arabidopsis and potato. Furthermore, we were able to show the generation of small RNAs of 21 nt size classes in the potato transgenics against the introduced GWSS RNAi targets. Small RNA read based mapping against HoCV-1 (single stranded RNA virus from dicistroviridae) and HoVRV (dsRNA virus from reoviridae) genomes displayed a diverse and contrasting pattern of small RNA mapping. In the case of HoCV-1, we observed intense mapping on positive-strand compared to the negative-strand, while the mapping frequency correlated higher to the negative-strands for the 12 genome segments of HoVRV.  Furthermore we have identified hotspot regions that were mapped with dense small RNA reads on both the viruses HoCV-1 and HoVRV and confirmed these by small RNA northern blot analysis.