Microsatellite-centromere mapping in zhikong scallop (Chlamys farreri) through half-tetrad analysis in D-shaped larvae of gynogenetic diploid families

Inheritance of 27 informative microsatellite loci was examined in 40-h D-shaped larvae of three induced meiogynogenetic diploid families of zhikong scallop (Chlamys farreri) for centromere mapping using half-tetrad analysis. Mendelian inheritance was confirmed for the loci by examining the genotypic segregation in three control crosses. Nine of the 27 microsatellite loci showed the existence of null alleles in control crosses. All gynogenetic offspring only possessed the alleles of the mother, indicating 100% success level for the three families. The second division segregation frequency (y) of the microsatellite loci ranged from 0.05 to 0.78 with a mean of 0.41, suggesting the existence of positive interference after a single chiasma formation in some chromosomes in the scallop. Microsatellite-centromere (M-C) distances ranged from 3 cM to 39 cM under the assumption of complete interference. Information on the positions of centromeres in relation to the microsatellite loci will represent a contribution towards assembly of genetic maps in the commercially important scallop species.