Symbiotic Relationship Between Bemisia Tabaci B And Its Endosymbionts And Annotation And Function Research Of Sugar Transporter Superfamily Of Bemisia Tabaci B

As an important invasive pest,Bemisia tabaci causes serious economic losses on many crops worldwide.Its growth,development,and production rely on nutrients,therefore,genes related to nutrients are vital for B.tabaci.In our study,based on the genomes of both B.tabaci Q and its symbionts,the amino acid,vitamin,nucleotide biosynthesis as well as purine,pyrimidine recylce and metabolism pathways were constructed by using bioinformatic analysis.In addition,sugar transporters were identified based on analysis of the genome and transcriptome of B.tabaci B.In order to identify potential targets for B.tabaci control,RNAi were applied to explore the potential effect of those genes.The main results are as follows:1.Based on the genomes of both B.tabaci Q and its symbionts,we found that B.tabaci Q and its primary symbiont Portiera could formed a complementary network for amino acid biosynthesis.Although B.tabaci and Portiera did not contain any genes involved in vitamins biosynthesis,the secondry symbiont Hamiltonella still kept its own vitamins biosynthesis genes,which indicated the secondry symbiont could supply vitamins for its host;2.Based on the genomes of both B.tabaci Q and its symbionts,we also identified that the genes involved in nucleotide biosynthesis and metabolic pathways,purine and pyrimidine recylcing pathways.Resuls showed that the symbionts could not synthesize nucleotide by itself and lost genes in the nucleotide metabolic pathway,purine,and pyrimidine recylcing pathways.However,those genes retained in the B.tabaci Q.Interestingly,we identified that the urea degradation pathway in B.tabaci Q,which lay a foundation for explaining both the unique urea degradation and the nitrogen cylces in B.tabaci Q;3.The two genes,BTUA and BTAP,which involved in B.tabaci Q urea degradation were identifed to be similar to bacteria genes based on the sequences analysis.Based on the molecular biology study and bioinformatic analysis,we confirmed that BTUA and BTAP were two horizontial transferred genes.Then,both BTUA and BTAP were silenced by RNAi.Results showed silencing BTUA could significantly increasing the mortality rate of B.tabaci Q,whereas there was no impant on the mortality of B.tabaci Q upon silencing BTAP.4.Based on the genome of B.tabaci B,the sugar transporters were identified.A total of 137 members were indentified and most of them located on the scaffold as tandem repeats.Transcriptome analysis showed the expressional pattern of the sugar transporters from B.tabaci B varied in different stages,whereas the expressional pattern of the sugar transporters from both B.tabaci B male and female adults which reared on different hosts had no difference.5.By comparing the sugar transporters of B.tabaci B and other selected insects,we found that B.tabaci B harbored the largest sugar transporter superfamily.Phylogenetic analysis showed that there were two specific expanded clades in the sugar transporter superfamily of B.tabaci B.Then,molecular evolution analysis showed the B.tabaci B sugar transporter genes in the specific expanded clades had fast evolved rates and the evolved rates were resulted from relaxed selection.6.Among all the sugar transporter genes in B.tabaci B,nine genes were selected for functional analysis.Their coding sequences were obtained based on cloning.Then,the nine genes were slienced respectively by oral delevery of dsRNA.The results showed that except BTST120 and BTST134,other seven genes could significantly decrease the survival rates of B.tabaci B adults.Among of these seven genes,silencing BTST40 had the best lethal effort on B.tabaci B adults.7.A total of three potential targets genes were identified,which laid a foundation for the further research on the B.tabaci biocontrol.