Genetic diversity and molecular markers of cupped oysters (genera Crassostrea, Saccostrea, and Striostrea) in Thailand revealed by randomly amplifiedpolymorphic DNA analysis

Genetic diversity and species-diagnostic markers of 5 oysters in Thailand, Crassostrea belcheri (Sowerby, 1871), Crassostrea iredalei (Faustino, 1932) , Saccostrea cucullata (Born, 1778), Saccostrea forskali (Gmelin, 1791), an d Striostrea (Parastriostrea) mytiloides (Lamarck, 1819), were investigated by randomly amplified polymorphic DNA (RAPD) analysis. In a total, 135, 12 7, and 108 genotypes were observed from primers OPA09, OPB01, and OPB08 (Op eron Technologies Inc., kits A and B), and 131 and 122 genotypes from prime rs UBC210 and UBC220 (University of British Columbia), respectively. Two hu ndred fifty-four reproducible and polymorphic fragments (200-2500 bp in len gth) were generated across the 5 investigated species. The average number o f bands per primer varied between 12.4 and 32.2. The percentage of polymorp hic bands within Crassostrea (53.23%-77.67%) was lower than that within Sac costrea and Striostrea oysters (86.21%-99.36%). Nine, species-specific mark ers were found in C. belcheri, 4 in C. iredalei, and 2 in S. cucullata. The mean of a ratio between the number of genotypes generated by each primer a nd the number of investigated specimens of C. belcheri (0.58) was lower tha n that of the remaining species (0.90-1.00). Genetic distances between pair s of oyster samples were between 0.105 and 0.811. A neighbor-joining tree i ndicated distant relationships between Crassostrea and Saccostrea oysters, but closer relationships were observed between the latter and Striostrea my tiloides.