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| Identification of Heterozygous Clone and Genetic Analysis of Growth Traits in Japanese Flounder |
| LIU Yong-xin,ZHAN Jin-mian,LIU Yi,WANG Gui-xing,LIU Hai-jin,LIU Ying-jie |
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Abstract In this study ,mitotic gynogenetic diploid Japanese flounder (Paralichthys olivaceus) were produced by activation of ultraviolet irradiated sperm of red sea bream ( Pagrosomus major ) , and by hydrostatic pressure treatment to block the first mitotic division to identity the heterozygous clone .Nine heterozygous clones (HC1-HC9) of Japanese flounder were produced by crossing nine males with nine females after these diploid flounder were cultivated until sexual maturity .Simultaneously ,two homozygous clones (C1-C2) were prepared by inducing two females to carry out meiotic gynogenesis .A set of 22 microsatellite markers with high polymorphism were selected from the second genetic linkage maps of Japanese flounder .Genetic status of these heterozygous clones was identified and the association between the number of heterozygous loci at alleles and phenotypic value for grow th traits of different heterozygous clones were analyzed .The results showed that the genotypes of heterozygous clone offsprings were identical and the combination of parental alleles ,indicating the successful development of heterozygous clones .The association analysis revealed that the minimal phenotypic values for growth traits were found in 2 homozygous clones including zero heterozygous loci .In 9 heterozygous clones ,the phenotypic value for growth traits of corresponding heterozygous clone was first increased and then decreased with increase in the number of heterozygous loci .The maximal phenotypic value for growth traits were found in HC5 containing 5 heterozygous loci .The HC9 had the maximum number of heterozygous loci ,but its phenotypic value for growth traits was not the optimum .Thus ,there was to some extent relationship between the number of heterozygous loci at alleles and phenotypic value for growth traits , which would provide theoretical references for parent selection of heterozygous clone and genetic improvement of objective traits in Japanese flounder in the future .
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Received: 25 January 2014
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