The ubiquitin-proteasome system (UPS) is an essential protagonist in host-pathogen interactions. Among the three classes of enzymes in the UPS, ubiquitin-conjugating enzyme E2 plays a dual role in viral pathogenesis; however, the role of insect E2s in interactions with plant viruses is unclear. Twenty E2-encoding genes in Laodelphax striatellus, the small brown planthopper, were identified and classified into 17 groups by transcriptomic and phylogenetic analysis. Full-length cDNAs of four LstrE2s (LstrE2 A/E/G2/H) were obtained by rapid-amplification of cDNA ends (RACE-PCR) analysis. Expression of the four LstrE2s showed tissue- and development-specific patterns. RT-qPCR analyses revealed that Rice stripe viruse (RSV) infection increased the level of LstrE2 A/E/G2/H. Further study indicated that repression of LstrE2 E via RNAi caused significant increases in the expression of RSV coat protein mRNA and protein levels. These findings suggest that LstrE2 E inhibits RSV accumulation in the planthopper body. Understanding the function of LstrE2 E in RSV accumulation may ultimately result in the development of novel antiviral strategies.
Keywords: Laodelphax striatellus; rice stripe virus; ubiquitin-conjugating enzyme E2; viral accumulation.