| Species of plant viruses transmitted by insects are diversity. These viruses do great harm to different plants.The process of viruses transmitted by insects is complex, including acquiring viruses,carrying viruses and transmitting viruses.Many proteins, including coat protein(CP),GroEL protein, Helper component(HC)and underside-jaw protein, are relative to this process. GroEL produced by endosymbionts protects viruses from being degraded by enzymes in insect. Endosymbionts include primary endosymbiont and secondary endosymbiont,accreting with insects.Endosymbiont affects the growth, ferlizing of insect and plays important roles on diseases transmitted by insects.At the same time, the symbiosis body is an excellent mode for investigating life's origin and evolution.Bemisia tabaci, a kind of important invaded pest in China, 27 biotypes were reported.The loss caused by B. tabaci-transmitting viral diseases were much more than that caused by its eating. In this thesis, reviews were given on the biological characters of B. tabaci, relative proteins and insect's endosymbionts.The potential values and directions for future research were also discussed.In order to probe into the reasons that B. tabaci distributed extensively and transmitted viruses diversitily,the studies on the endosymbionts in B. (abaci were conducted for the first time in China.The results will help explain invasive mechanism of B. tabaci.The results are as the followings:1.The study on the morpholory of endosymbionts in B.tabaci and Trialeurodes vaporariorum was conducted by transmission electron microscope.The results showed that B.tabaci had both rod and coccid morphological mycetocytes.The rods were more than the coccids.The primary endosymbionts in B. tabaci lived in the rod-shaped mycetocytes.The secondary endosymbionts in B. tabaci lived in the coccoid-shaped mycetocytes. Mycetocytes of T. vaporariorum had coccid shape only.The primary endosymbionts in T. vaporariorum lived in this mycetocyte.2.B. tabaci and T. vaporariorum are small insects. It's difficult to identify them by nake eyes.Seen through dissection microscope, they can be differed from imago, puparium,and so on.They also can be distinguished by biochemical methods,such as enzyme system.Endosymbionts accreted with insects and evolved to cooperate with insects.In order to probe into the function of endosymbionts on identification of B. tabaci and T.vaporariorum,PCR technique was used to distinguish B.tabaci from T. vaporariorum.The results showed that four special primers were acquired, two for groEL,the others for 16S rDNA of primary endosymbiont and secondary endosymbiont in B.tabaci respectively.The groEL of endosymbiont in B. tabaci was 99.5% similar to the sequence AF130421,a groEL sequence of endosymbiont in B.tabaci from GenBank.The about 1 000bp 16S rDNA of primary endosymbiont and about 1 250bp 16S rDNA of secondary endosymbiont in B. tabaci was 98% similar to the corresponding sequences from GenBank respectively.But they were not suitable for amplifying from T. vaporariorum. It also proved that endosymbionts in B.tabaci and T. vaporariorum were different.It could help explain the difference of host plant and transmission of plant viruses between B. tabaci and T.vapomriorum.3. Endosymbionts evolute with insects and benefit from each other. Cloning and sequencing of 16S rDNA of primary endosymbionts and secondary endosymbionts in B. (abaci long-term living on different host plants in Beijing were conducted.Molecular phylogenetic trees,including about 1 000bp 16S rDNA of primary endosymbionts in B. tabaci,and about 1 250bpl6S rDNA of secondary endosymbionts in B.tabaci were reconstructed.The results showed that primary endosymbionts in B.tabaci were Proteobacteria;Gammaproteobacteria;Oceanospirillales;Halomonadaceae;Zymobacte; Candidatus Portiera aleyrodidarum.Secondary endosymbionts in B. tabaci were Proleobacteria;Uammaproteobacleria;Enterobacteriales Enterobacteriaceae. The primary endosymbiont and secondary endosymbiont in B. tabaci from different host plants and o...
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