A second generation genetic linkage map for silver carp (Hypophthalmichehys molitrix) using microsatellite markers

Abstract

In the study, we constructed a second generation genetic linkage map for silver carp (Hypophthalmichthys molitrix) using anonymous and EST-derived microsatellite markers in a mapping panel containing 156 “pseudo BC” progenies from two interspecific crosses between silver carp and bighead carp (Aristichthys nobilis). A total of 703 markers were ordered on 24 linkage groups (LGs) which are equal to chromosome numbers of the haploid genome of the species. The consensus map spanned 1561.1cM covering 93.1% of the silver carp genome with an average resolution of 2.2cM/locus. Length of LGs ranged from 42.1cM to 97.8cM (mean 65.0cM). Total number of markers on individual LG varied from 13 to 56 (mean 29.3). Estimated total length of the female map (1809.0cM) was 1.52 times longer than that of the male map (1188.5cM), and the recombination ratio between sexes (female vs. male) was 2.2, showing markedly higher recombination in the females. Percentage of distorted loci in the male map was obviously higher than that in the female map, and 5 segregation distortion regions were identified in the male linkage groups. This second generation genetic linkage map evidently extends previous genetic maps for silver carp, and provides a basis for such studies as quantitative trait locus mapping, comparative genomics and marker-assisted selection.