关键词: 茶籽象, ATP合成酶基因, 遗传分化, 系统发育, 海拔, 选择压力

Abstract: [Objective] The camellia weevil, Curculio chinensis (Coleoptera:Curculionidae), is a host-specific parasite of camellia seeds and has caused huge economic losses in China. Despite its economic impact, the genetic diversity is rarely understood. In this study, based on the genetic differentiation and structural variation of mitochondrial ATP synthase gene of C. chinensis in different regions, the influence of environmental selection pressure, especially the geographical altitude, on the genetic diversity and the phylogenetic structure of different geographical populations of C. chinensis was studied, and the changes of bases as well as their amino acid sequence structure of ATP synthase gene in adapting to environmental pressure were discussed, which is important to provide theoretical basis for establishing a control strategy of this pest.[Method] The populations of camellia weevil at different geographical altitudes were collected from the main oil-tea production areas. The specific primers of ATP synthase gene were designed and the ATP synthase gene was amplified by PCR. Genetic diversity and phylogenetic structure were estimated based on ATP gene sequences, and the structural differences of amino acids sequences and frequency were moreover analyzed.[Result] Genetic diversity and the phylogenetic structure of C. chinensis were inferred using the sequences of ATP synthase gene among different geographical populations. Thirty-two haplotypes (NCBI:MH560360-MH560391) in 119 individuals from all the sample regions in China were obtained. There was no obvious regularity in the genetic diversity differentiation of various geographical populations of camellia weevil (Nucleotide diversity π:0.000 86-0.048 03). The population expansion of camellia weevil was not significant (Tajima's D<0, P>0.05; Fu's Fs>0). Based on the geographical altitudes, all the samples of camellia weevil can significantly divided into two branches (F_st=0.374, P<0.001) under different selection pressures (Choice index:ω_{high altitude}=1.65, ω_{low altitude}=2.26, LRT P<0.001). ATP8 gene in the samples of low altitude branch (36 conservative sites) was more conservative compared to that in high altitude branch (27 conservative sites), and acidic amino acid utilization rate in high altitude branch was higher than that in low altitude branch, which might be related to the increase of protein stability, oxygen binding efficiency and oxidative respiratory efficiency of insects to adapt to high altitude.[Conclusion] The differentiation degree of ATP synthase gene in C. chinensis populations is low, but there is significant adaptation evolution to geographical altitude.

Key words: Curculio chinensis, ATP synthase gene, genetic differentiation, phylogenetic structure, geographical altitude, environmental selection pressure