珠江野生卷口鱼遗传多样性的RAPD分析

RAPD analysis of genetic diversity in Ptychio jordani from Pearl River

应用RAPD技术对珠江水系西江段广西桂平至广东肇庆之间的野生卷口鱼遗传多样性进行分析。利用20个随机引物对卷口鱼30个个体的基因组DNA进行了PCR扩增，一共扩增出3840条DNA片段，平均每个个体扩增出128条带。在检测到的128个位点中，多态位点数为85个，占66．4％，标记的分子量在0．2～3kb之间。个体间最大的遗传距离为0．2913，个体间最小的遗传距离为0．0291。30个个体间的平均遗传距离为0．1501±0．0343。与野生草鱼、鲫鱼、黄颡鱼、胭脂鱼等相比，卷口鱼的遗传多样性水平较高，表明野生卷口鱼可能存在较大的群体。采用临近聚类法（NJTREE）构建了30个个体相互关系的分支图。30个个体被分为两个群体，显示野生卷口鱼在广西桂平至广东肇庆之间的江段中可能至少存在两个种群。本研究为卷口鱼的种质保护、合理开发利用以及选择育种提供了一些基础数据。

Ratmouth barbell（ Ptychio jordani Myers ）is a member of the family Cyprinidae and mainly distributes in Pear River and Taiwan Island in southern China, especially in Xijiang River-the biggest branch of Pearl River. It has high values for food, and for aquaculture in China. But the genetic backgrotmd of Ratmouth barbel is not very clear. In this paper, the genetic diversity of 30 individuals of Ratmouth barbel collected from Xijiang River was detected by the random amplified polymorphic DNA （RAPD） technique with 20 10- base primers and analyzed by RAPDistance1.04 program. 3840 well-amplified DNA fragments were produced by 20 primers, the average of DNA fragments was 128 in each individual. 85 of 128 loci detected were polymorphic, amounting to 66.4%. The size of DNA fragments was from 0.2 kb to 3 kb. The genetic distance of individuals was from 0.023 4 to 0.438 6. The average genetic distance was 0.1501±0.034 3 among the 30 individuals. The phylogenetic tree of the 30 individuals was obtained by NJTREE analysis in the RAPDistance 1.04 program and the 30 individuals were divided into 2 main clusters. Compared with grass carp （Ctenopharyngodon idellus ）, crucian carp （Carassius carassius ）, bullhead catfish （Pelteobagms fulvidraco ）, Chinese sucker （ Myxocyprinus asiaticus ）, the genetic diversity of Ratmouth barbel is high, and there maybe exist two natural geographical populations in the fiver from Zhaoqing city to Guiping city, suggesting that species in the Pear River still has great potential of survival and evolution.