Abstract：TRAP (target region amplified polymorphism) was used for comparison of genetic structures among three populations of grass carp (Ctenopharyngodon idella), one wild population from Jiangsu Hanjiang National Four Major Chinese Carps Seed Farm and two cultured populations from Freshwater Fisheries Research Center Aquatic Breeding plant and Wuxi Qianzhou Aquatic Breeding plant. Seven primer combinations selected from 15 primer combinations produced good amplified patterns and 103 amplified loci from three populations were obtained. The numbers of polymorphic loci in Hanjiang population, Freshwater Fisheries Research Center population and Qianzhou population were 67, 55, and 46 respectively. It indicated that genetic polymorphism decreased in two cultured grass carp populations. Compared with wild population, only 39.98% loci gene frequency kept being unchanged in two cultured ones. It showed that the genetic structure of cultured populations had changed. The genetic distances between wild population and two cultured populations were 0.0421 and 0.0809, respectively. With primer combination Ga5-800-E5, a region was detected in electrophoretic pattern in which the number of amplified loci reduced apparently in cultured populations. This will offer scientific basis for developing of molecular markers to distinguish wild population from cultured ones.
