Studies on Characteristics of 16S rDNA Sequences from Endosymbionts in Bemisia tabaci

Abstract:

The studies on enzymes digested sites and (G+C)mol% of 16S rDNA gene from endosymbionts in B.tabaci were conducted.The results showed that:16S rDNA from primary endosymbiont in B. tabaci could be digested into two segments by EcoR I,but not by BamH I or Sac I.16S rDNA from secondary endosymbiont in B. tabaci could be digested into two segments by EcoR I or Sac I respectively, but not by BamH I. The (G+C)mol% of 16S rDNA varied according to creature species and culturable characters. For example, 16S rDNA of primary endosymbiont (Proteobacteria γ subdivision) in B. tabaci were as rich in （A+T）mol% and poor in（G+C）mol% as 16S rDNA of Rickettsia and mitochondria (Proteobacteria α subdivision), which are cell ware or unculturable microbes.The 16S rDNA from secondary endosymbiont (Proteobacteria γ subdivision) in B. tabaci and primary endosymbiont (Proteobacteria β subdivision) in mealybugs, both were unculturable, were as rich in (G+C)mol% as those of E.coli (Proteobacteria γ subdivision), a kind of culturable bacterium.As a result,primary endosymbiont was a concurrence and concerted evolution with B. tabaci. Secondary endosymbiont was similar to free-living bacteria and might be easier to be cultured. Molecular phylogenetic trees based on 16S rDNA of different creatures showed that secondary endosymbiont in B. tabaci was Proteobacteria γ-3 subdivision.Primary endosymbiont in B. tabaci was aonther Proteobacteria γ subdivision.