文蛤（Meretrix meretrix）4个壳色花纹品系的遗传差异分析

摘要

Genetic variations of four strains ofMeretrix meretrix, i.e., thin checkered （TC）, black spot （BS）, dark fringe （DF） and red shell （RS）, were examined using amplified fragment length polymorphism （AFLP）. 15 AFLP primer combinations were applied to analyze the genetic diversities and relationships among these strains. 29 strain-specific bands were found in overall 789 detectable bands. These strain-specific bands may be used to distinguish these four strains. The overall percentage of the polymorphic loci of these four strains was 90.75% and the percentage of the polymorphic loci ranged from 61.34% to 75.16%. Nei＇s genetic diversity analysis and Shannon＇s information index showed that the levels of genetic diversity were in the order of BS 〉 RS 〉 DF 〉 TC. AMOVA analysis indicated that the average fixation index （Fst） was 0.2055%, with 79.45% of variance from within strains and 20.55% of variance from among strains. The results of a cluster analysis indicated that the TC strain had the highest genetic variation, the BS strain ranked the second, and genetic variations between the DF and RS strain were the lowest. One AFLP marker only existed in the TC strain and the frequency was 100%. These results suggested that the unique band of TC strains could be a molecular marker which can be used for strain identification purposes.%应用AFLP技术对文蛤红壳（RS）、黑斑（BS）、细纹（TC）、暗纹（DF）4个壳色花纹品系进行遗传差异分析。利用15对AFLP引物组合对4品系共128个个体进行了PCR扩增和电泳检测，共得到789个位点，总多态位点比例90．75％。Nei’s基因多样性和Shannon’s信息指数显示，4个品系的遗传多样性大小,依次为BS品系〉RS品系〉DF品系〉TC品系。AMOVA分析表明，79．45％的变异来自品系内，品系间的变异只占20．55％。聚类分析结果表明，4个品系间存在较明显的遗传差异，TC品系与其他品系的遗传差异最大，DF品系和RS品系的遗传差异相对较小。发现1个TC品系特有的AFLP标记．其出现频率为1．000，可作为品系鉴别的特征性标记。