PAG-V: W10 - GENETICS OF FARMED OYSTER SPECIES: CURRENT STATUS

Plant & Animal Genome V Conference

Town & Country Hotel, San Diego, CA, January 12-16, 1997.

W10

GENETICS OF FARMED OYSTER SPECIES: CURRENT STATUS

GAFFNEY, PATRICK M.(1), Standish K., Jr. Allen(2), Dennis Hedgecock(3)
1. University of Delaware, College of Marine Studies, Lewes, DE 19958
2. Haskin Shellfish Research Laboratory, Institute of Marine and Coastal Sciences, Rutgers University, Port Norris, NJ 08349
3. Bodega Marine Laboratory, University of California, Davis, Bodega Bay, CA 94923

Oyster species of the genus Crassostrea are commercially cultured worldwide. Generally, aquacultural production supplements wild harvests, and cultured stocks are little different from natural populations. However, small-scale selective breeding programs for improved growth and disease resistance have achieved positive results, and recently larger programs for both eastern and Pacific oysters (C. virginica and C. gigas, respectively) have been started in the U.S. with USDA and NOAA support. As wild harvests decline, the role of aquaculture is expanding, increasing the demand for genetically improved strains of shellfish. Crassostrea oysters are attractive candidates for genomic mapping for several reasons. They possess a relatively small genome (N=10 chromosomes, 0.7 pg haploid DNA content) that is karyotypically conserved throughout the genus. Much of the work on artificial polyploid shellfish has used Crassostrea species, and the use of aneuploids for dissecting phenotypes, genetic mapping, and gene transfer is being explored. Comparative genomic analyses will also benefit by considering a major taxonomic group that has so far received little attention. Inheritance data are available for allozymes, microsatellites, and anonymous nuclear loci, including two linkage groups of allozymes. For the eastern oyster, a P1 genomic library and an archive of pedigreed families has recently been created; these will be used to develop new DNA markers and to establish linkage relationships. Fifty inbred lines of the Pacific oyster are being used for QTL mapping. Many loci exhibit non-Mendelian segregation, which may reflect the massive early zygotic mortality typical of highly fecund species. Genotypic analysis of gametes and early embryonic stages may remedy this problem. Research efforts in the U.S. are informally coordinated, and an effort is under way to establish international collaboration.