Exploration And Transferability Evaluation Of SSRs In Chlamys Farreri And Patinopecten Yessoensis And Parentage Identification

1 A preliminary study on microsatellite markers screening from EST sequences of Patinopecten yessoensisWe developed a series of EST-SSR markers using a transcriptome-based platform to study the genetic diversity of Patinopecten yessoensis.We identified 9,317 EST-SSR using MISA software and designed 125 primers for PCR.It showed that 60 out of 125 resulted in successful application and 44 primers were polymorphic.Next we used these SSR primers to explore the genetic variation of 30 P.yessoensis samples collected from Yantai Bay.A total of 109 alleles were produced with an average of 2.48 alleles per locus.The average observed heterozygosity,the average expected heterozygosity and polymorphic information content were 0.4492,0.4440 and 0.3560,respectively.These indicated low genetic diversity of the P.yessoensis in the Yantai Bay.Moreover,we verified that the polymorphic EST-SSR markers could be a useful tool in gene tagging,comparative mapping.2 Transferability of EST-SSR from Patinopecten yessoensis in Chlamys farreri60 EST-SSRs of Patinopecten yessoensis were selected to analyze the transferability in Chlamys farreri.According to unique flanking sequences of each motif,21 and 17 EST-SSR primers can gain unique target PCR products,having the transferability of 35.00% in larval stage and 28.33% in one-year-old stage.In the populations of P.yessoensis and C.farreri,the number of alleles were ranged from 2.00-4.00,mean allele were 2.7647 and 2.3529,respectively;the mean effective number of allele were 1.9487 and 1.6350;the mean observed heterozygosity were 0.6314 and 0.3333;the mean expected heterozygosity were 0.4569 and 0.3139;the mean polymorphism information content were 0.3726 and 0.2597;Nei's(1973)gene diversity index were 0.4493 and 0.3087;Shannon's Information index were 0.7176 and 0.5041;gentic identity was 0.619;genetic distance was 0.480;seven loci were found to be significantly departed from Hardy-Weinberg Equilibrium;genetic differentiation index was 0.2398.It has great significance for developing P.yessoensis and C.farreri EST-SSRs markers and studying their transferability,applying in genetic diversity analysis,gene discovery and evaluation on germplasm resources.3 EST-SSR analysis of the F1 hybrids of scallop Chlamys farreri(?)× Patinopecten yessoensis(?)21 universal EST-SSR loci from Patinopecten yessoensis and Chlamys farreri were used for scallop hybrid identification and the genetic investigation between parents and hybrids.13 primers out of 21 were amplified to the genome DNA of D larvae F1 and 21 to adult F1.The average alleles of P.yessoensis,C.farreri and D larvae F1 were 2.5385,2.000 and 2.4615.The average observed heterozygosity were 0.6333,0.2410 and 0.4872.The average expected heterozygosity were 0.4543,0.2269 and 0.3921 and polymorphic information content were 0.3644,0.2102 and 0.2506,respectively.The genetic distance between D larvae F1 and parents were 0.4099 and 0.3024.Accumulative exclusion rate of 13 EST-SSRs was 99.80%.The average alleles of P.yessoensis,C.farreri and adult F1 were 2.6667,2.0952 and 2.5714.The average observed heterozygosity were 0.6302,0.2698 and 0.3365.The average expected heterozygosity were 0.4491,0.2541 and 0.3000 and polymorphic information content were 0.3644,0.2102 and 0.2506,respectively.The genetic distance between adult F1 and parents were 0.4975 and 0.3538.Accumulative exclusion rate of 17 EST-SSRs was 100.00%.In this study,21 pairs of universal EST-SSR markers were identified for hybrid progeny,which will lay the foundation for further develop genetic diversity analysis,molecular assisted breeding,gene discovery and germplasm evaluation of hybrid scallops.