Genome-wide Identification And Comparative Analysis Of Chemosensory Protein Genes In Bemisia Tabaci Biotypes B And Q1

The whitefly Bemisia tabaci(Hemiptera:Aleyrodidae)is a complex species composed of at least 24 morphologically indistinguishable biotypes.Biotypes B and Q1 are regarded as the two most invasive and destructive whiteflies.The most dominant whiteflys in China now are B biotype B and Q1.In recent years,B.tabaci causes excessive crop losses through direct feeding and transmission of plant viruses.Several studies have been focused on the comparative analysis of host adaptation among B.tabaci species complex and pair-wise comparisons of B.tabaci biotypes B and Q1 indicate that biotypes B and Q1 has significant difference in feeding behavior and oviposition sites.The insect olfaction system is particularly sensitive and important in finding food sources,courtship,mating and oviposition sites.Chemosensory proteins(CSPs),odorant binding proteins(OBPs)and other olfactory proteins are essential members in insect olfaction system.In this study,we do the Genome-wide identification of chemosensory proteins in biotype B and biotype Q1,surveyed its expression in various developmental stages and adult tissues,in order to further study more olfactory-related proteins of B.tabaci and understand the difference of the olfactory system of B.tabaci.1.We identified a total of 16 candidate BtabBCSP genes in the genome of B.tabaci biotype B and 16 of candidate BtabQ1CSP genes in the genome of B.tabaci biotype Q1.Through the comparative analysis,the identity percentage of 15 BtabBCSPs versus BtabQ1CSPs is 100%,1 BtabBCSP has identities higher than 80%.Bemisia tabaci biotypes B and Q1 have identified total 32 CSP genes,30 of these genes have complete open-reading frame(ORF)and contain putative signal peptide at the N-terminus.However,BtabBCSP10 and BtabQ1CSP 10 have complete open-reading freme and no putative signal peptide at the N-terminus,respectively.The deduced amino acid sequence of BtabBCSP 10 and BtabQ1CSP10 are 738.The deduced amino acid sequence of BtabBCSP2 and BtabQ1CSP1 contain putative signal peptide of 19 and 18 amino acid residues at the N-terminus,respectively.Among the 32 candidate CSPs,all of them contain intact 4 conserved cysteine residues.According to the phylogenetic analysis,the BtabBCSPs and BtabQ1CSPs are scattered among several groups.While both BtabBCSP3,BtabBCSP6 and BtabBCSP13 are distinctly different from other known CSPs,BtabBCSP2 and the identified BtabBCSP12 and BtabBCSP14 are clustered together in one independent branch distinguished from other CSPs.2.According to the analysis of expression profiling of chemosensory protein genes of B.tabaci biotype B and Q1 in different developmental stages,BtabQ1CSP1 in 1-day-old adult had the highest expression,followed by fourth-instar nymphs.BtabQ1CSP3 and BtabQ1CSP7 both had the highest expression in First-instar nymphs and Second-instar nymphs.BtabQ1CSP4 in the egg had the highest expression and in the female adult had the lowest expression.BtabQ1CSP1 1 in the female adult had the highest expression.Therefore,BtabQ1CSP13 had higher expression in First-instar nymphs than in the adult.Other CSP genes had same expression patten.Besides BtabQ1CSP2 in the First-instar nymphs had higest expression,CSPs in B.tabaci biotype B had the same expression patten with B.tabaci biotype Q1.3.According to the analysis of expression profiling of chemosensory protein genes of B.tabaci biotype B and Q1 in different host like cabbage and derived cucumber,cotton and tomato,we find that BtabBCSP1 and BtabBCSP2 in the four host had the same expression.BtabBCSP12 in the cotton had the lowest expression while BtabBCSP12 in the cotton had the highest expression.These different expression genes may be relate to feeding behavior and host-associated differentiation.