用RAPD分析对罗非鱼遗传变异的研究及其对杂种优势的应用

A STUDY ON GENETIC VARIATION OF TILAPIAS FISH WITHRAPD ANALYSIS AND ITS APPLICATION TO HETEROSIS

应用ＲＡＰＤ技术检测了一个奥利亚罗非鱼养殖群体和湘湖、美国和沙市三个尼罗罗非鱼养殖群体。在２０个引物中筛选到１２个引物，它们的扩增产物显示了奥利亚罗非鱼和尼罗罗非鱼在群体内或群体间存在遗传差异。ＯＰＺ０６、ＰＯＺ１０、ＯＰＺ１２和ＯＰＺ１９四个引物都有一个扩增片段（大小分别是９００、１５００、１７００和７３０ｂｐ）具有种的特异性，可以作为鉴别尼罗罗非鱼和奥利亚罗非鱼的分子遗传标记。群体内遗传相似性指数（Ｓ）表明，湘湖、美国和沙市三群体尼罗罗非鱼都保留了较高水平的遗传变异（Ｓ分别为０．７９８、０．７９５和０．８２４），而奥利亚罗非鱼的群体内遗传变异最小（Ｓ＝０．９５０）。显示尼罗罗非鱼具备选育优良品种的遗传潜力，奥利亚罗非鱼的这种潜力就较小。奥利亚罗非鱼和湘湖、美国、沙市三群体尼罗罗非鱼之间的遗传距离分别是０．２８５、０．２６２和０．３４４，说明奥利亚罗非鱼和沙市群体尼罗罗非鱼杂交将可能产生更强的杂种优势。

Three cultured populations (Xianghu, American and Shashi) of Oreochromis nilloticus and one cultured population of O.aureus were examined using RAPD method.12 primers were screened out of 20 random primers,and each of the 12 primers revealed interor/and intrapopulation genetic variation.There were four speciesspecific amplification bands (sizing 900, 1500, 1700 and 730 bp respectively) of primers OPZ06, OPZ10, OPZ12 and OPZ19, each of which could be used as molecular genetic markers to identify O.niloticusTBZ and O.aureus . Genetic similarity indices (S) suggested that the three populations of O.niloticus maintained the higher degrees of the intrapopulation genetic variation (S for the three populations of Xianghu, American and Shashi were 0.798, 0.795 and 0.824 respectively), and O.aureus had the smallest degree of genetic variation(S=0.950) because of two times of genetic bottleneck effect.The data suggest that there is the genetic potential of developing new O.niloticus varieties, while there is relatively small genetic potential in O.aureus . Interspecific genetic distances between O.aureus and three populations of O.niloticus were 0.285, 0.262 and 0.344, respectively, which suggest that the offspring of O.aureus and Shashi population of WTBXO.niloticus will develop stronger heterosis than that of other two cross combinations.