文蛤30个微卫星标记的开发及在斧文蛤和帘文蛤中的通用性检测

Identification of 30 microsatellite markers in Meretrix meretrix and their transferability in Meretrix lamarckii and Meretrix lyrata

为开展文蛤多态性微卫星标记及其在斧文蛤和帘文蛤中的通用性研究,实验从磁珠富集法构建的基因组文库和EST文库中开发了30个文蛤多态性微卫星标记,包括8个G-SSR和22个EST-SSR多态性位点。共获得140个等位基因,平均等位基因数为4.67;多态性信息含量、观测杂合度、期望杂合度分别为0.172～0.744、0.040～0.720、0.187～0.793;G-SSRs的平均等位基因数、平均多态性信息含量、平均观测杂合度和平均期望杂合度都较EST-SSRs高;Hardy-Weinberg平衡检测发现,24个位点偏离了平衡状态;利用BLASTx对含多态性SSR位点的EST进行功能注释,11个位点来自注释基因序列。将30对文蛤多态性SSR引物分别在斧文蛤和帘文蛤中进行了通用性检测,通用率分别为40%和30%。这些微卫星多态性位点的获得,为进一步开展文蛤遗传多样性分析、种质资源评价、分子标记辅助选育等奠定了基础,并且可用于文蛤、斧文蛤和帘文蛤的比较作图、基因发掘和QTL定位等研究。

30 microsatellite loci of Mereteix meretrix were developed using microsatellite-enhanced genornic library and expressed sequence tags （ESTs）. Genetic diversity was analyzed in a population consisting of 30 individuals. 8 G-SSRs and 22 EST-SSRs were found to be polymorphic. In these 30 microsatellite loci, a total of 140 alleles were identified,and the number of alleles varied from 3 to 6, with a mean of 4.67 alleles per locus. Polymorphic information content（PIC）ranged from 0. 172 to 0.744. The observed heterozygosity （Ho ）was from 0.040 to 0.720 ,while the expected heterozygosity （He ）was from 0. 187 to 0. 793. The mean values of number of alleles ,PIC,Ho ,and He of G-SSRs were higher than those of the EST-SSRs. 24 of the 30 loci deviated from the Hardy-Weinberg equilibrium after Bonferroni correction. 11 EST-SSR identified from annotated genes were expected to be useful for mapping these genes in linkage maps. Interspecific transferability of the 30 markers revealed that 12 and 9 were polymorphic in M. lamarckii and M. lyrata ,respectively. These loci obtained will lay a foundation for the study of genetic diversity, germplasm resources evaluation, marker-assisted selection （MAS） and other relevant research in M. meretrix, and these novel polymorphic SSR markers can be used for comparative mapping ,gene tagging and QTL mapping among M. meretrix,M, lamarckii and M. lyrata.