Transcriptome-wide responses of adult melon thrips (Thrips palmi) associated with capsicum chlorosis virus infection

Abstract

Thrips palmi is a widely distributed major agricultural pest in the tropics and subtropics, causing significant losses in cucurbit and solanaceous crops through feeding damage and transmission of tospoviruses. Thrips palmi is a vector of capsicum chlorosis virus (CaCV) in Australia. The present understanding of transmission biology and potential effects of CaCV on T. palmi is limited. To gain insights into molecular responses to CaCV infection, we performed RNA-Seq to identify thrips transcripts that are differentially-abundant during virus infection of adults. De-novo assembly of the transcriptome generated from whole bodies of T. palmi adults generated 166,445 contigs, of which ~24% contained a predicted open reading frame. We identified 1,389 differentially-expressed (DE) transcripts, with comparable numbers up- (708) and down-regulated (681) in virus-exposed thrips compared to non-exposed thrips. Approximately 59% of these DE transcripts had significant matches to NCBI non-redundant proteins (Blastx) and Blast2GO identified provisional functional categories among the up-regulated transcripts in virus-exposed thrips including innate immune response-related genes, salivary gland and/or gut-associated genes and vitellogenin genes. The majority of the immune-related proteins are known to serve functions in lysosome activity and melanisation in insects. Most of the up-regulated oral and extra-oral digestion-associated genes appear to be involved in digestion of proteins, lipids and plant cell wall components which may indirectly enhance the likelihood or frequency of virus transmission or may be involved in the regulation of host defence responses. Most of the down-regulated transcripts fell into the gene ontology functional category of ‘structural constituent of cuticle’. Comparison to DE genes responsive to tomato spotted wilt virus in Frankliniella occidentalis indicates conservation of some thrips molecular responses to infection by different tospoviruses. This study assembled the first transcriptome in the genus Thrips and provides important data to broaden our understanding of networks of molecular interactions between thrips and tospoviruses.

Chromosome‐level assembly of the melon thrips genome yields insights into evolution of a sap‐sucking lifestyle and pesticide resistance

“…These genomic resources in Hemiptera provide an opportunity to compare the evolution of the sap-sucking lifestyle in thysanopteran and hemipteran insects. A well-assembled reference genome is also essential in understanding other aspects of the ecology, evolution and control of thrips, and can be used to build on transcriptomic studies that have examined pesticide resistance and virus transmission in thrips (Berger et al, 2016;Gamage, Rotenberg, Schneweis, Tsai, & Dietzgen, 2018;Schneweis, Whitfield, & Rotenberg, 2017;Wan et al, 2018).…”

Integration of transcriptomics and network analysis reveals co-expressed genes in Frankliniella occidentalis guts that respond to tomato spotted wilt virus infection

“…There was little to no overlap in virus-responsive DETs across the three larval stage-times (Figure 1B). The two stages farthest apart in developmental time (3-L1 and 48-L2) shared the most in number of DETs (13), which might be expected given the few number of DETs associated with the early L2 stage (24-L2). The 13 shared DETs have provisional gene ontologies of proteolysis and hydrolysis, carbohydrate metabolism, lipid metabolism, and structural constituent of cuticles, such as transmembrane protease serine, putative beta-glucosidase, myrosinase, acyl-CoA desaturase, and endocuticle structural glycoprotein.…”

In silico analyses of molecular interactions between groundnut bud necrosis virus and its vector, Thrips palmi

“…Recently, transcriptome-wide responses of adult T. palmi to infection by capsicum chlorosis virus (CaCV; genus Tospovirus) were determined. Cathepsin was found to be upregulated in CaCV exposed T. palmi [45]. However, the exact role of cathepsin L in tospovirus glycoprotein maturation remains to be studied.…”