Abstract
BackgroundThe brown planthopper (Nilaparvata lugens) is one of the most destructive rice plant pests in Asia. N. lugens causes extensive damage to rice by sucking rice phloem sap, which results in hopper burn (complete death of the rice plants). Despite its importance, little is known about the digestion, development and defense mechanisms of this hemimetabolous insect pest. In this study, we aim to identify the serine protease (SP) and serine protease homolog (SPH) genes, which form a large family in eukaryotes, due to the potential for multiple physiological roles. Having a fully sequenced genome for N. lugens allows us to perform in-depth analysis of the gene structures, reveal the evolutionary relationships and predict the physiological functions of SP genes.ResultsThe genome- and transcriptome-wide analysis identified 90 putative SP (65) and SPH (25) genes in N. lugens. Detailed gene information regarding the exon-intron organization, size, distribution and transcription orientation in the genome revealed that many SP/SPH loci are closely situated on the same scaffold, indicating the frequent occurrence of gene duplications in this large gene family. The gene expression profiles revealed new findings with regard to how SPs/SPHs respond to bacterial infections as well as their tissue-, development- and sex-specific expressions.ConclusionsOur findings provide comprehensive gene sequence resources and expression profiles of the N. lugens SP and SPH genes, which give insights into clarifying the potentially functional roles of these genes in the biological processes including development, digestion, reproduction and immunity.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2164-15-507) contains supplementary material, which is available to authorized users.
Highlights
The brown planthopper (Nilaparvata lugens) is one of the most destructive rice plant pests in Asia
Identification of SP and serine protease homolog (SPH) genes in the N. lugens genome We identified a total of 90 predicted serine protease-like genes by searching the N. lugens genome sequence based on the KEGG, Swissprot and Trembl annotations, which were validated using the tBLASTX algorithm with a cut-off E-value of 10−10 (Table 1)
The predicted sequences reveal that approximately 70% of the SPs and SPHs are sized, while a few of them are larger and contain specific modules, such as Clip domain, complement control protein (CCP) domain, low-density lipoprotein receptor class A (LDLA) domain, myb/SANT-like (MADF) domain, complement CUB domain, frizzled (FRI) domain and scavenger receptor Cys-rich (SR) domain
Summary
The brown planthopper (Nilaparvata lugens) is one of the most destructive rice plant pests in Asia. The target gene silencing based on RNA interference (RNAi) technology has been considered for its feasibility and potential in protecting crops against agriculturally important lepidopteran and Serine proteases (SPs) in the chymotrypsin (S1) family constitute one of the largest gene families of multifunctional enzymes that play important roles in various physiological processes, including digestion, development and the immune response [7]. They are the principal proteolytic digestive enzymes in certain insects and provide nutrients required for survival and fecundity. Nonproteolytic SPHs are important components of phenoloxidase activation in insect innate immune responses [9]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
