黄颡鱼属物种的RAPD分子鉴定及杂种遗传分析

MOLECULAR IDENTIFICATION OF THE FOUR SPECIES OF THE GENUS PELTEOBAGRUS AND THE GENETIC ANALYSIS OF THEIR HYBRID

使用20个随机引物研究了4种黄颡鱼的RAPD图谱,其中6个可以用来准确鉴别4个种,分别是S1、S2、S5、S7、S8、S17。同时也分析了4种黄颡鱼之间的亲缘关系,发现种间遗传距离D值在0.5000左右波动,黄颡鱼-叉尾黄颡鱼、瓦氏黄颡鱼-光泽黄颡鱼之间的D值最小,分别是0.4816和0.4017。聚类图显示,黄颡鱼和叉尾黄颡鱼属同一分支;瓦氏黄颡鱼和光泽黄颡鱼属另一分支,说明它们之间分别有更近的亲缘关系。另外,采用黄颡鱼作母本,瓦氏黄颡鱼作父本,获得了杂交F1代,对F1代进行RAPD分析,发现了杂种遗传图谱的三种变化情况:叠加、叠加-变异、叠加-弱化,表明F1代DNA多态性增强,杂合性提高,预示着杂种优势的可能性。

The genus Pelteobagrus is classified in Order Siluriformer, Family Siluridae, consisting of 4 species： P. fulvidraco, P. vachelli, P. nitidus and P. eupogon. They are similar in morphological characters, which are easily influenced by the geographical regions and environments. Therefore, it is often difficult to identify them accurately at morphological level. It is necessary to research the genetic difference and identify them more distinctly. RAPD（ Random Amplification of Polymorphic DNA） technique, as an important tool for genetic study, is widely used in identification of species. 20 random primers（Sl-S20）were used to study the RAPD patterns of 4 species of genus Pelteobagrus, 6（S1, S2, S5, S7, S8, S17）among which could be employed to identify the 4 species. Each species bore a unique band with the primer S7 used to RAPD amplification, while the others did not. We also studied the phylogenetic relationships of this 4 species based on the data obtained from RAPD analysis above, and found that the genetic distance fluctuated at the point of 0. 5000. The genetic distance values of P. fulvidraco and P. eupogon, P. vachelli and P. nitidus were the least ,0.4816 and 0.4017 respectively. The phylogenetic tree showed that P.fulvidraco and P. eupogon originated from a common branch, while P. vachelli and P. nitidus from another one. That indicated that they were closer in relationship. To study difference between the RAPD patterns of parents and that of offspring, in addition, individuals of P. fulvidraco （ ♀ ） and P. vachelli （ ♂ ） were hybridized, and a group of F1 offsprings were generated. We investigated the offspings by RAPD method and found three types of genetic patterns： full overlapping, overlapping-variation and overlapping-faintness. This indicated the DNA polymorphism of F1 offspings was increased, which forecasted the possiblility of heterosis.