Sequencing And Phylogenetic Analysis Of The Orf7Gene Of WO Phage In An Oak Gall Wasp, Andricus Mairei (Hymenoptera:Cynipidae)

Wolbachia is an obligate intracellular symbiont infecting various species of arthropods and filarial nematodes, where it is maternally inherited through the germ line cells. In arthropods, Wolbachia is most known for the ability to manipulate the reproduction of their hosts in various ways, which include induction of parthenogenesis, feminization, male killing, and cytoplasmic incompatibility(CI). This study collected Andricus mairei Kieffer, an oak gall wasp (Cynipini, Cynipidae) that forms clusters of up to90monothalamous galls in the catkins of Quercus glandulifera var. brevipetiolata Nakai, we examined the presence and infection frequency of WO phage,which is a temperate bacteriophage of Wolbachia, in three widely separated geographic populations of A. mairei in Changsha luan and xinyang, using polymerase chain reaction and sequence determination of the or7gene of WO phage from the three populations. Based on analysis of these sequences including base composition, site composition, transition/transersion ratio, And analyzing the different types of gall wasp WO phylogenetic relationships. The conclusion of experimental as follows:(1) We confirmed the presence and infection frequency of WO in three widely separated geographic populations of Andricus mairei. The results showed that WO infection rates are100%for the wasps from all populations, and the orf7fragments were371bps in size.(2) Use the software MEGA5.0comparing the orf7gene sequence analysis showed that:The total site of wsp gene sequences is381, among them, the conservative sites is272, the variable sites is99, the parimony information sites is34and the singleton site is65. The average contents of A, C, T and G to orf7gene of17species in wasps are39.6%、12.6%、26.3%and21.5%, respectively. A+T content is65.9.1%,, which shows a strong A+T bias.(3) Among the nucleotide substitution of the sequences, the transition rate of or/7is7.87%, the transversion rate is6.30%, transution sites are30tranversion sites are24,transution/tranversion ratio is1.62. The base saturability analysis showed that orf 7gene sequences are not saturated state.(4) The orf7gene sequence consistency are between83-99%. The sequence consistency with Ephestia cautella wECauA-1and Asobara tabida wAtabA3-3strain is99%,with D. simulans wHa Al strain is83%.(5) Genetic distances shows that the distance of orf7gene from0to0.1756, The average distance is0.0697. The distance between Andricus mairei and Asobara tabida is the smallest(0.0028). the distance between Andricus mairei and D. simulans is the largest(0.1652).(6) In the five phylogenetic trees, Phylogenic reconstruction the relationship of WO strains with known orf7sequences indicated that the WO strain of Andricus mairei is closely related to that of Asobara tabida (strain1), belongs to the Ⅲ group.