DEVELOPMENT AND CHARACTERIZATION OF POLYMORPHIC EST MARKERS IN COMMON CARP

Expressed sequence tags (ESTs) are of high value in genome mapping and marker-assisted selection (MAS).Thisstudy aims to develop EST markers for genome mapping and other studies of common carp (Cyprinus carpio L).A total of 7381EST sequences (400.3500bp) were downloaded from the EST database of theGenBank as the source data of the present analy-ses.Sixty-seven pairs of primers (designated as HB1-67) were designed in the 3? untranslated region (UTR) of the common carpESTs,47 of which can successfully amplify specific products fromgenomicDNA.Twelve polymorphicEST markers were identifiedin a backcross mapping family of common carp by single-strand conformation polymorphism (SSCP) analysis.Six of the 12 poly-morphicEST markerswere derived from common carp genes of known function, and the rest were from common carp ESTs homolo-gous to putative genes in zebrafish (Danio rerio) or channel catfish (Ictaluruspunctatus).Alleledistribution of these polymorphicEST markers was found to follow theMendelian segregation (1.1 or 3.1) in both the backcross family and gynogenetic haploids,and the number of SSCP bands in haploid population was half of that in diploid family.Thegene diversity (H=0.437) of Dongt-ing Lake population of common carp revealed by 4 polymorphic EST markers is much lower than that by previous microsatelliteanalysis (close to 1).The results of present study indicated that EST-SSCP markers,with codominant inheritance, can be used asa powerful tool in the genetics of not only diploid but also haploid common carp.As TypeI marker derived from coding region withrelatively lower genetic variability, EST-SSCP markers are still of high potentials in such studies as genome mapping (includinggenetic linkagemaps and genemaps, as well as comparative mapping), genetic structure, and genetic adaptability of fish popula-tions.