Transcriptional changes associated with Tomato spotted wilt virus infection in various life stages of its thrips vector, Frankliniella fusca [Hinds]

Thrips transmitted Tomato spotted wilt virus (TSWV) is a type member of the genus Tospovirus in the family Bunyaviridae. TSWV is an economically important plant pathogen worldwide. TSWV is transmitted in a persistent propagative manner. Also, TSWV acquisition during early larval stages is requisite for TSWV transmission. Fitness studies conducted on tobacco thrips, Frankliniella fusca [Hinds] and TSWV demonstrated positive effects of TSWV-infection on F. fusca oviposition. However, TSWV-infection negatively affected F. fusca adult survival rate. To elucidate TSWV-induced changes in F. fusca at molecular levels, in this study, we adapted a transcriptomic approach. We examined transcriptional changes associated with TSWV-infection in F. fusca at various life stages using Illumina HiSeq sequencing system. We identified a total of 1,161 differentially expressed contigs in larvae, pupae, and adults. Annotations revealed upregulation of contigs associated with virus movement such as clathrin-mediated endocytosis in viruliferous adults. Also, as expected, homologs of proteins associated with virus replication were identified in viruliferous adults. We further documented upregulation of contigs associated with immune pathways including apoptosis and RNAi, mostly in viruliferous adults. In viruliferous larvae, contigs associated with development including neuron development and cell division were downregulated. Despite evidence for potential negative effects, upregulation of contigs associated with egg production and embryo development were also documented in viruliferous adults. This study provided insights into stage specific transcriptional changes associated with TSWV–infection in F. fusca. It also provided transcriptional supports for positive and negative effects of TSWV-infection on F. fusca fitness documented in our previous studies.