Molecular and in vitro biochemical assessment of chemosensory protein 10 from brown planthopper Nilaparvata lugens at acidic pH

Chemosensory proteins(CSPs)are important molecular components of the insect olfactory system,which are involved in capturing,binding,and transporting hydrophobic odour molecules across the sensillum in sensillar lymph in regulating insect behavior.This protein family(CSPs)is also involved in many other systems that are not linked to olfactory receptors in olfactory sensilla.The brown planthopper(BPH)is a monophagous pest of rice that causes damage by sucking phloem sap and transmitting a number of diseases caused by viruses.In this study,fluorescence competitive binding assay and fluorescence quenching assay at acidic p H were performed as well as homology modelling to describe the binding affinity of Nlug CSP10.Fluorescence competitive binding assay(FCBA)demonstrated that Nlug CSP10 bound strongly to nonadecane,farnesene,and 2-tridecanone at acidic p H.The results of FCBA indicated that Nlug CSP10 bound different ligands at the physiological p H(5.0)of the bulk sensillum lymph.Fluorescence quenching assay demonstrated that Nlug CSP10 generated a stable complex with 2-tridecanone,while two ligands nonadecane and farnesene collided due to molecular collisions.The interaction of selected ligands with the modelled structure of Nlug CSP10 was also analyzed,which found the key amino acids(Gln23,Gln24,Gln25,Asn27,Met33,Ser34,Ile35,Tyr36,Asn42,Met43,Val45,Asn46,Asn93,Arg96,Ala97,Lys99,and Ala100)in Nlug CSP10 that were involved in binding of volatile compounds.The present study contributes to the binding profile of Nlug CSP10 that promotes the development of behaviorally active ligands based on BPH olfactory system.

Identification and characterization of odorant binding proteins in the diamondback moth,Plutella xylostella

Odorant binding proteins(OBPs)are a group of soluble proteins functioning as odorant carriers in insect antennae,mouth parts and other chemosensory organs.However,multiple insect OBPs have been detected in other tissues and various functions have been proposed.Therefore,a detailed expression profile including stages,tissues and sexes where OBPs are expressed will assist in building the links to their potential functions,enhancing the functional studies of insect OBPs.Here,we identified 39 putative OBP genes from its genome and transcriptome sequences of diamondback moth(DBM),Plutella xylostella.The expression patterns of identified PxylOBPs were further investigated from eggs,larvae,pupae,virgin adults,mated adults,larval midgut,larval heads,adult antennae,adult heads and adult tarsi.Moreover,P.xylostella larvae and adults with and without host plants for 5 h were utilized to study the interactions between OBP expression and host plants.The results showed that most PxylOBPs were highly expressed in male and female adult antennae.The expression levels of certain PxyOBPs could be regulated by mating activities and feeding host plants.This study advances our knowledge of P.xylostella OBPs,which may help develop new strategies for more environmentally sustainable management of P.xylostella.