Characterization of Capa Peptide and Its Receptor in Bemisia Tabaci

Abstract

The diuresis process in insects is regulated by CAPA neuropeptides, which activate the specific cognate receptor i.e CAPAr. In this study, we characterized the CAPAr gene (BtabCAPAr) in whitefly, Bemisia tabaci Asia II 1 for the first time. The two splicing isoforms of the BtabCAPAr gene i.e BtabCAPAr-1 and BtabCAPAr-2 which included six (421 aa) and five (355 aa) exons, respectively were recorded. The third exon was missing in the BtabCAPAr-2 isoform. The transmembrane topology depicted the presence of seven and five transmembrane regions in BtabCAPAr-1 and BtabCAPAr-2, respectively. The relative BtabCAPAr gene expression in different whitefly life stages revealed the highest (3.76 folds) expression level of the BtabCAPAr gene in the adult stage as compared to the egg stage. The expression of the BtabCAPAr gene in the nymphal and pupal stage did not differ significantly with each other as well as egg stage. Two peptides, CAPA-PVK1 and CAPA-PVK2 were identified through a functional luminescence assay, which strongly activated the BtabCAPAr-1 receptor with very low EC50 values of 0.067 nM and 0.053 nM, respectively. The basic information generated in the study will help develop biostable peptides, which can be tested further and may lead to the development of new generation insecticides.