Identification And Function Exploration Of Chemosensory Genes In Bemisia Tabaci B And Q

Bemisia tabaci is a major agricultural pest worldwide,harming more than 600 host plants.B.tabaci is a compound species composed of a variety of biotypes or cryptic species.There are significant differences in the host range,poison transmission ability and drug resistance of various B.tabaci,and only B and Q B.tabaci in China,it can really cause actual harm in production.Olfactory-related genes are important participants in insect olfactory system and the molecular basis of insect olfactory activity.We have previously found that when faced with plants infected with tomato yellow leaf curl virus(TYLCV)and healthy plants,B.tabaci Q tends to choose virus-infected plants,while B.tabaci B has no obvious preference.In order to clarify the molecular mechanism behind TYLCV's regulation of B and Q B.tabaci host selection,this study started with chemical sensitization-related genes,and through bioinformatics,molecular biology and electrophysiology techniques,finally found the reason for the difference.The main research conclusions are as follows:1.The odorant substances which can stimulate the antennae of B.tabaci were obtained:11 compounds were screened and EAG experiments were carried out on the antennae of B.tabaci.Five odorant compounds(?-Myrcene,?-Pinene,?-Ocimene,P-Cymene and ?-Humulene)can stimulate the antennae of B.tabaci strongly when the concentration is 10 ?g/?L,and(3-Myrcene can also stimulate the antennae of B.tabaci strongly when the concentration is 1?g/?L.B.tabaci may be sensitive to ?-Myrcene and may be related to host recognition.2.Identification and functions exploration of the OBP gene family in B.tabaci B and Q:The result shows clear that B.tabaci B and Q both have 8 OBPs,which are divided into 1 Minus-C OBP,2 Plus-C OBP and 5 Classic OBP.Through the fluorescent competition binding experiment,the selected odor substances were combined with OBP.It was found that similar OBP between B.tabaci B and Q can bind the same odor substances.Among them,BtabOBP5 protein can be combined with ?-elemene and ?-pinene,in which ?-pinene has stronger binding ability to BtabOBP5 protein.BtabOBP8 protein has better binding ability with ?-myrcene.3.Identification and functions exploration of the OR gene family in B.tabaci B and Q:We found that B.tabaci B and Q both have 7 ORs,which can be divided into 1 atypical odorant receptor and 6 typical odorant receptors,qRCP results show that the OR gene is mainly expressed in the head of B.tabaci,which is consistent with the function that the OR gene is mainly involved in the recognition of insect odor substances;The phylogenetic tree results show that the B.tabaci OR gene has a species-specific branch,which may be related to the recognition ability of B.tabaci specific hosts;The sequence similarity between OR1,OR2 and OR3 of B.tabaci B and Q reached more than 99%,and the sequence similarity between OR5 and OR6 of B.tabaci B and Q was less than 40%;Then carried out Xenopus oocyte system and two-electrode voltage clamp experiment for OR5 and OR6.We found that B.tabaci B and Q OR5 gene can not feel the selected odor substances.B.tabaci Q OR6 gene can feel ?-Myrcene,showing potential changes,while the B.tabaci B OR6 gene could not;further free selection experiments showed that ?-myrcene had a certain attractive effect on B.tabaci B and Q,so it is speculated that the B.tabaci Q OR6 gene helps it identify and feel ?-myrcene stimulation,and then tend to choose select plants with ?-myrcene.4.Identification of the GR and IR gene family in B.tabaci B and Q:12 GR genes and 10 IR genes of B.tabaci B and Q were identified.B.tabaci B and Q GR genes have a high similarity(basically more than 90%),while IR3,IR5 and IR9 genes have obvious differences(sequence similarity is less than 70%).The results of gene expression profiling found that IR1,IR3,GR6 and GR10 had significant differences in expression of B.tabaci B and Q,indicating that these four genes may be related to the differences in the identification of B.tabaci B and Q.These need more research.5.The function of cspll gene of B.tabaci Q:Odorant-binding proteins(OBPs)and the chemosensory proteins(CSPs)are involved in the transport process of olfactory recognition.In this study,a CSP11 gene from Bemisia tabaci,BtabCSPll,was cloned and characterized.The open reading frame of BtabCSP11 encodes 136 amino acids,with four highly conserved cysteine residues.The temporal and spatial expression profiles of BtabCSPll showed that BtabCSP11 was highly expressed in the abdomen of adult females.Functional analysis of BtabCSP11 using dietary RNA interference(RNAi)substantially reduced the number of eggs laid by the parthenogenetically reproduced females,suggesting a potential role of BtabCSP11 in B.tabaci.With a comparable hatching rate and the same oviposition site,the reduced egg production in the BtabCSPll knockdown whiteflies is likely the results of a compromised oviposition behavior.These combined results diversify the functions of CSPs in insects beyond chemosensation.