Plant, Animal & Microbe Genomes X Conference Plant, Animal & Microbe Genomes X ConferenceJanuary 12-16, 2002
Town & Country Convention Center
San Diego, CA
Workshop: Aquaculture
The Pacific oyster Crassostrea gigas is one of the most important species in aquaculture. The development of a genetic linkage map, using microsatellite markers, will be an important tool for the genetic improvement of this species. Combining 91 newly cloned and 23 previously published microsatellite DNA markers, we obtained 114 microsatellite markers for linkage mapping in C. gigas. These markers were tested on three outbred families, using 11-day-old larvae, to reduce segregation distortion caused by recessive deleterious mutations (Launey & Hedgecock 2001 Genetics 159:255; Hubert et al. http://www.intl-pag.org/pag/9/abstracts/W10_010.html). Of the 102 markers that are informative in at least one of these families, 98 are placed onto a consensus linkage map comprising 11 linkage groups and 880cM. Four microsatellite markers are unlinked. The genetic data compare favorably with the 10 pairs of chromosomes observed in cupped oysters and a map length estimated to be between 600 and 1000 cM, based on the frequency of chiasmata. Important discrepancies in map distances are found between male and female parents and among families. Seventy-eight new microsatellites were also tested on four different Crassostrea species; 76 work for C. angulata, 65 for C. sikamea, 30 for C. ariakensis, and 8 for C. virginica. The decline in ability to amplify these markers across congeneric species, together with a high frequency of null alleles within C. gigas (40% of the loci are segregating for a null allele in at least one family), implies rapid evolution of primer target-sequences in oysters.