Discovery and evaluation of exon-primed intron-crossing (EPIC)-PCR markers for the Pacific oyster (Crassostrea gigas)

摘要

The Pacific oyster (Crassostrea gigas) has had the highest single species production of cultured aquatic animals since 1993, reaching 4.2 million metric tonnes in 2007 (FAO 2009). Various types of molecular markers including randomly amplified polymorphic DNA (Aranishi & Okimoto 2004), amplified fragment length polymorphism (Li & Guo 2004) and restriction fragment length polymorphism (Okimoto, Hara, Ishihara & Aranishi 2008) have been used for genetic studies in C. gigas. Because of the high polymorphism, abundance, codominance and small length, development of microsatellites is especially desirable in C. gigas for population studies, parentage analysis, as well as genetic mapping. Using microsatellite DNA-enrichment protocols, numerous microsatellite DNA loci have been identified (Li, Hubert, Bucklin, Ribes & Hedgecock 2003; Sekino, Hamaguchi, Aranishi & Okoshi 2003), and about 100 of these were used for mapping purposes and for establishing a genetic linkage map (Hubert & Hedgecock 2004). Higher density maps, required for quantitative trait loci or genome scan studies, rely on the development of additional microsatellites. However, high frequencies of null alleles (Hedgecock, Li, Hubert, Bucklin & Ribes 2004) and segregation distortions (Launey & Hedgecock 2001) have been frequently observed in microsatellite loci of C. gigas, leading to additional constraints in the development of high-density linkage maps (Sauvage, Boudry & Lapègue 2009).