中华鳖2个培育品系的16S rRNA基因多态性比较分析

Comparative analyses of 16S rRNA genetic diversity in newly cultured varieties of Pelodiscus sinensis

以中华鳖(Pelodiscus sinensis)日本品系、清溪乌鳖两个国家水产新品种为研究对象,并以中华鳖黄河群体和台湾群体为对照,克隆测序获得了其16S rRNA基因全长序列1 606 bp,并对群体遗传多样性进行比较分析。结果表明,在4群体共80个个体中,共检测到53个变异位点,包括9个群体特异性位点,其中清溪乌鳖3个,中华鳖日本品系和黄河种群各1个,台湾群体4个;共发现16种单倍型,其中清溪乌鳖8个、中华鳖日本品系2个、中华鳖黄河群体和台湾群体各3个,群体间无共享单倍型。中华鳖不同群体的16S rRNA基因多样性从高到低依次为清溪乌鳖(0.821)、中华鳖台湾群体(0.484)、中华鳖黄河群体(0.195)、中华鳖日本品系(0.100)。中华鳖日本品系和黄河群体、清溪乌鳖和台湾群体的遗传距离相对较近,分别为0.001和0.005。不同群体的单倍型各自聚为一支,表明中华鳖群体分化较为明显,不同群体的特异性位点可作为种质鉴别的依据。单倍型进化树显示,中华鳖日本品系和黄河群体以很高的置信度聚为一支,推测中华鳖日本品系起源于中国黄河流域。

The Chinese soft-shelled turtle （Pelodiscus sinensis） is one of the most important commercial freshwater species in China and, in recent years, its aquaculture has developed rapidly. However, with the expansion in cultivation scale, promiscuity and mixing between different populations has necessitated research on the genetic diversity of this species. A Japanese breed and Qingxi black mutant population are two new varieties of P. sinensis now found in China. Molecular research on these two new varieties is of great importance in the identification, germplasm protection and guidance of breeding studies on P. sinensis. In this study, the 16S rRNA gene from 80 individuals of four populations （Yellow River, Japanese, Qingxi black mutant and Taiwan） of P. sinensis was amplified and sequenced for analyses of mutations, diversity parameters and phylogenetic relationships. A total of 53 mutation sites were detected in the studied gene including nine specific sites. A total of three specific sites were detected in the Qingxi black mutant population, one in the Japanese breed, one in the Yellow River population and four in the Taiwan population. The Qingxi black mu-tant population displayed the highest haplotype genetic diversity （0.821） followed by the Taiwan （0.484）, Yellow River （0.195） and Japanese populations （0.100）. The detected mutant sites added up to 16 haplotypes, including three in the Yellow River population, two in the Japanese, eight in the Qingxi black mutant and three in the Taiwan population. Phylogenetic relationship and genetic distance analyses showed a similar result in that the Yellow River and Qingxi black mutant population reflected a relatively closer relationship to the Japanese and Taiwan population, respectively. Phylogenetic trees of haplotypes indicated that the four populations showed clear differentiation and can be identified effectively. The Japanese and Yellow River populations displayed a close relationship, indicating that the Pelodiscus sinensis Japanese breed possibly originated in the Yellow River basin of China.