苹果属小金海棠的遗传多样性初步研究

用RAPD技术建立了苹果属小金海棠（Malus xiaojinensis）2个自然分布区的3个群体内随机选取的30株树（10株／每群体）及其相应的子代实生苗共6个群体、60个样本植株的分子标记。通过对15个3承机引物产生的81条RAPD这的统计，计算了不同群体RAPD多态性带的数目。用TREECON软件分析了不同群体及所有个体间的遗传关系，并用AMOVA技术分析了物种的遗传变异。结果是15个引物在全部分析个体中产生了58条多态性带，平均每引物3.8条。现有分布3个群体及其相应的子代实生苗群体的平均多态性带的数目都为1.5条左右。其中平均多态性带的数目最低的群体仅有0.7条，最高的群体也只有2.5条。遗传关系分析表明，2个自然分布区的不同群体间存在遗传分化现象。AMOVA分析显示小金海棠的遗传变异有相当一部分来源于群体间。

A preliminary study on the genetic diversity of Malus xiaojinensis

Thirty trees of Malus xiaojinensis randomly sampled from three natural populations in two distribution areas (about 50 kilometers apart), i.e. Dengcun of Mopo and Lianghe townships, Xiaojin County, Sichuan Province, and thirty corresponding seedlings were analyzed using random amplified polymorphic DNA (RAPD) techniques. Based on statistical analysis of the 81 RAPD bands produced by 15 decamer primers in polymerase chain reactions (PCR) with all of the DNA samples studied, the number of polymorphic RAPD bands among all the individuals and different populations were counted. The genetic relationship among all the individual trees and between different populations were analyzed using Nei and Li (1979) genetic distance and neighbor joining methods in the TREECON software package. Genetic variance analysis was carried out using the AMOVA method in Arlequin Ver. 2.000 software package. From 15 random decamers, 81 polymorphic bands were produced in all the DNA samples studied, average 3.8 bands per primer. The average polymorphic RAPD bands of both three existing populations and their corresponding descendent seedling populations were about 1.5 per primer. Among them, the highest average polymorphic RAPD bands per population is 2.5 and the lowest is 0.7. The genetic relationship trees constructed by the TREECON computer program for all the individuals and different populations show that there is genetic differentiation among the populations of M. xiaojinensis . The AMOVA analysis indicates that the seedling population variances composed a large part of the species genetic variation of M. xiaojinensis .