Zheng Kang, Lin Kaidong, Liu Zhenghua, Luo Chen
Institute of Biology, Hunan Normal University, Changsha 410081, China.
J Genet Genomics. 2007 Apr;34(4):321-30. doi: 10.1016/S1673-8527(07)60034-4.
The genomes of three groups of grass carp, namely the Xiangjiang River grass carp group (Xiangjiang group), a one-generation artificially induced meio-gynogenetic grass carp group (meio-gynogenetic-1 group), and a two-generation artificially induced meio-gynogenetic grass carp group (meio-gynogenetic-2 group), were comparatively analyzed with microsatellite markers. Genetic polymorphism had been observed in the Xiangjiang group and most of the examined loci had more than two alleles. But the degree of genetic diversity was not very high. Although all the examined genetic loci in the analyzed individuals were in homozygous state, the genotypes of different individuals of the group were not identical in the meio-gynogenetic-1 group. In the meio-gynogenetic-2 group, not only the examined genetic loci of each individual were homozygous but also the genotypes of all the analyzed individuals of the group were the same. These results suggested that the examined meio-gynogenetic-2 group is a homozygous group and homozygous clone could be produced by continuous artificial induction of gynogenesis for two generations. It was found that the polymorphism existed not only at the allele level but also at the locus level; many alleles of the microsatellite loci and some of the microsatellite loci had been lost during the process of artificial gynogenesis. Therefore, both protection of the diversity of natural grass carp resource and selection of homozygous traits with desired economic genotypes are very important aspects for grass carp breeding.
利用微卫星标记对三组草鱼基因组进行了比较分析，这三组草鱼分别是湘江草鱼群体（湘江群体）、一代人工诱导雌核发育草鱼群体（雌核发育-1群体）和二代人工诱导雌核发育草鱼群体（雌核发育-2群体）。在湘江群体中观察到了遗传多态性，大多数检测位点有两个以上的等位基因。但遗传多样性程度不是很高。在雌核发育-1群体中，虽然分析个体中所有检测的遗传位点均处于纯合状态，但该群体不同个体的基因型并不相同。在雌核发育-2群体中，不仅每个个体检测的遗传位点是纯合的，而且该群体所有分析个体的基因型都是相同的。这些结果表明，检测的雌核发育-2群体是一个纯合群体，通过连续两代人工诱导雌核发育可以产生纯合克隆。研究发现，多态性不仅存在于等位基因水平，也存在于位点水平；在人工雌核发育过程中，微卫星位点的许多等位基因和一些微卫星位点已经丢失。因此，保护天然草鱼资源的多样性和选择具有所需经济基因型的纯合性状都是草鱼育种的非常重要的方面。
