Characterization of 34 polymorphic EST-SSR markers in Tegillarca granosa and their transferability in Anadara craticulata

EST-SSR is one of important methods to isolate microsatellite loci,which is low cost,high transferability among phylogenetically related species and a probability of being associated with functional regions of the genome.34 polymorphic EST-SSR markers were isolated and characterized in the blood clam,Tegillarca granosa,from the ESTs generated by 454 sequencing.The number of alleles for the 34 SSR markers in 30 individuals of Zhejiang Fenghua population varied from 2 to 7,with an average of 3.59 alleles per locus.The observed heterozygosity ranged from 0.000 to 0.600,while the expected heterozygosity varied from 0.078 to 0.771.Polymorphic information content ranged from 0.106 to 0.718,and 13 SSR loci deviated from Hardy-Weinberg equilibrium.25 EST-SSR identified from annotated genes were expected to be useful for mapping these genes in linkage maps.Interspecific transferability of the 34 markers revealed that 8 were polymorphic in Anadara craticulata,resulting in a transferability rate of 23.53%.To our knowledge,this is the first report on the survey of SSR transferability in blood clams.These novel polymorphic EST-SSR markers should be particularly useful for comparative mapping,gene tagging and QTL mapping among blood clams.