基于线粒体COI基因序列的4个海域口虾蛄群体的遗传多样性研究

摘要

为比较中国不同海域口虾蛄(Oratosqilla oratoria)群体的遗传特性,作者对采自皮口、绥中、青岛和广州4个海域的口虾蛄群体的线粒体COI基因序列进行扩增和测序,比较并分析了其遗传多样性和系统进化关系。获得585bp的口虾蛄线粒体COI基因序列,发现变异位点54个,占总位点数的9.2%。COI基因序列 A+T含量(64.8%)显著高于 G+T含量(35.2%),符合节肢动物线粒体 DNA碱基组成的特点。转换与颠换的平均比值是7.84,碱基替换未达到饱和。100个样本的线粒体 COI 基因序列共定义35个单倍型,单倍型多样性(Hd)为0.9162,平均核苷酸多样性(π)为0.0203。4个群体均具有高的单倍型多样性和低的核苷酸多样性的特点,说明4个海域口虾蛄的遗传多样性均处于中等水平,但广州海域的遗传多样性水平最高。AMOVA分析表明,来自于群体间的遗传差异(84.53%)明显高于来自群体内的差异(15.47%)。遗传分化系数(Fst)表明皮口、绥中、青岛3个海域间几乎没有发生分化(Fst<0),而广州海域口虾蛄遗传分化较大。从 GenBank 上下载了19条粤东海域口虾蛄的同源序列与本实验获得序列共同构建 NJ 系统发育树,结果显示皮口、绥中、青岛聚为一支,广州和粤东(深圳和汕尾)聚为另一支。单倍型系统发育树和单倍型进化网络关系图均显示出广州海域口虾蛄群体较大的遗传分化。%Oratosqilla oratoriais an important economic species in coastal areas of China and has high nutritional value. This paper analyzes and summarizes the hereditary feature ofO.oratoria from different sea waters by a comparative study. Four populations ofO.oratoriawere collected from Pikou, Suizhong, Qingdao and Guangzhou sea waters of China. The genetic diversity and phylogenetic relationship were analyzed by amplifying and se-quencing the mitochondrial cytochrome oxidase subunit I (COI) gene ofO.oratoria.A total of 54 variable sites (9.2%) and 35 haplotypes were detected in 585 bp sites for 100COI sequences.COI sequences were analyzed and the results indicated that the A+T content (64.8%) was higher than that of C+G (35.2%), corresponding with the characteristics of Arthropods’s mitochondrialCOI gene. The ratio of TV and TS was 7.84, indicating that the base substitution ofCOI gene was not satured inO.oratoria. The average values of haplotype and nucleotide diversity were 0.9616 and 0.02027. The results of haplotype and nucleotide diversity analysis in four different populations of O.oratoria showed a middle genetic diversity, but the genetic diversity level of Guangzhou was the highest. AMOVA analysis showed that the genetic difference among populations (84.53%) was significantly higher than that within populations (15.47%). The fix index (Fst) across all populations revealed that there were no genetic differen-tiations among Pikou, Suizhong and Qingdao sea waters (Fst<0), but Guangzhou had a high level. Nineteen ho-mologous sequences ofO.oratoria of the eastern coast of Guangdong province were downloaded from GenBank, together with the sequences obtained in this study, a neighbor-joining tree was constructed the. The results revealed that the five populations could be divided into two groups, one group included Pikou, Suizhong and Qingdao popu-lations and the other group included Guangzhou and the east coast of Guangdong province. The haplotype phy-logenetic tree and haplotype network from all haplotypes was constructed which all revealed the big genetic differ-entiation ofO.oratoriain Guangzhou seawaters. The genetic variation and the genetic structure of fourO.oratoria populations were analyzes. These results could provide a molecular biology basis for protection and reasonable utilization of germplasm resources ofO.oratoria in the coastal areas of China.