星斑川鲽、石鲽及其杂交一代(星斑川鲽♀×石鲽♂)的线粒体DNA序列比较分析

摘要

本研究以线粒体基因细胞色素b (Cytochrome b,Cytb)和细胞色素C氧化酶Ⅰ(Cytochrome oxidase subunitⅠ,COI)为研究对象,探究比较了星斑川鲽(Platichthys stellatus)、石鲽(Kareius bicolorarus)以及杂交F1代(星斑川鲽♀×石鲽♂)的种质遗传特性.结果显示,杂交子代与亲本的碱基(A+T)含量均高于(C+G)含量,且杂交F1代与母本星斑川鲽的(C+G)相同.基于mtDNA Cytb和COI序列结果显示,石鲽与星斑川鲽遗传距离分别为0.085和0.045;杂交F1代与石鲽遗传距离分别为0.076和0.045.基于mtDNA Cytb序列显示,杂交F1代与星斑川鲽遗传距离很小,仅0.009,而两者在COI基因序列上完全一致.基于Kimura 2-parameter模型的NJ分子系统树均显示,星斑川鲽和杂交F1代聚为一支,石鲽单独聚为一支.以上结果均可得出,杂交后代在线粒体DNA上呈现明显的母系遗传.杂交后代中出现左右眼的分化,且在COI的NJ系统树中,杂交F1代与母本星斑川鲽形成的一大支又分为两支:母本星斑川鲽与杂交F1代中外观显示左眼的聚为一支,杂交F1代中外观显示右眼的单独聚为一小支.表明线粒体基因COI与杂交F1代左右眼的分化有一定关系,为进一步研究星斑川鲽♀x石鲽♂提供了参考数据.%Platichthys stellatus and Kareius bicoloratus are two common Pleuronectidae species that are highly valuable in the aquaculture industry.P.stellatus is endowed with high meat content and delicious taste while K.bicoloratus is highly resistant to diseases.Characteristics of their hybrids,however,were rarely reported.In this study,we explored the genetic variability of mtDNA sequences of P.stellatus,K.bicoloratus and their hybrid (P.stellatus♀ ×K.bicoloratus♂),using 24 P.stellatus,24 K.bicoloratus and 40 hybrids as samples.We found that that the content of A+T base pairs was higher than that of the C+G base pairs in all 3 groups,and that the content of A+T base pairs in the hybrids was the same as in P.stellatus.The analysis of mtDNA Cytb gene and COI fragments suggested that the genetic distances between K.bicoloratus and P.stellatus were 0.085 and 0.045 respectively,and that the genetic distances between the hybrids and K.bicoloratus were 0.076 and 0.045 separately.Moreover,there was a very small differentiation (0.009) between the hybrids and P.stellatus based on the mtDNA Cytb sequence analysis,and there was no genetic differentiation between the 2 groups based on the mtDNA COI gene sequence analysis.The neighbor-joining (NJ) phylogeny trees constructed with the Kimura 2-parameter model showed that P stellatus and the hybrid could be clustered into one branch,while K.bicoloratus belonged to another branch.In the NJ phylogenetic tree based on gene COI,the big branch including F1 hybrid and P.stellatus could be further divided into two small branches.One was P.stellatus and F1 hybrid with the left eyes,and the other was the F1 hybrid with the right eyes.These data strongly suggested that characteristics of the hybrid of P.stellatus and K.bicoloratus (P.stellatus ♀ x K.bicoloratus♂) were maternally inherited.This study provided helpful information for the future research on the hybridization of the two species.