利用分子标记和形态学性状检测的陆地棉栽培品种遗传多样性

利用RAPD，ISSR和SSR3种分子标记方法和2年田间实验对国内外36个陆地棉栽培品种的遗传多样性进行了研究，以3种分子标记在36个品种之间扩增的282条多态性位点所赋值的0，1数据，采用Nei和Li的方法，计算的品种成对相似系数从0．5745到0．9291，其品种平均数从0．6547到0．7524，又以2年品种表现的性状平均数经正态标准化后，采用欧氏距离计算了成对品种的遗传距离。分别以相似系数和传距离矩阵，采用类平均法进行聚类分析，其聚类结果把供试品种大致分为国外品种，新疆品种，早熟类型品种和我国的中熟棉品种等几个类群，类内进一步分组表明，分子标记确定的传关系基本上与品种系谱的种质系统一致，但并不能按系谱或种植生态区域简单地归属，尽管分子标记数据计算的相似系数矩阵和表现型计算的遗传距离矩阵存在极显著的相关关系（r=-0.335)，但以遗传距离进行聚类分析的类内分组的组间特征不明显，分子标记是检测类内品种间遗传差异的有效方法，研究结果为棉花育种亲本选配提供了理论依据。

Genetic Diversity Detected by DNA Markers and Phenotypes in Upland Cotton

Genetic diversity of Upland cotton (Gossypium hirsutum L.) cult ivars was evaluated by SSR, ISSR, and RAPD. The genomic DNAs of 36 domestic and exotic cultivars were amplified with 81 SSR primer pairs; 7 ISSR primers and 53 RAPD primers, which yielded 282 polymorphic bands. The range of pair similarity coefficient (Nei, M. And W. Li 1979) between cultivars is from 0.5745 to 0.9 291. The result indicated that although the present cultivars have genetic variation to a certain extent, the genetic basis of them is relatively narrow, and it is essential to find some new germplasm for the development of new cultivars. As ex pected, the classification of the cotton cultivars using the Unweighted Pair-gr oup Method with Arithmetic Average based on the pair similarity coefficients is mostly consistent with known pedigree information and breeding experience. The 3 6 cotton cultivars have been mainly classed into exotic cultivar group, Chinese Xinjiang ecological region cultivar group, early-mature domestic cutivar group and mediate-mature domestic cultivar group. Carmen and Colorado cultivars from Spain have the lowest similarity with other cultivars, while TM-1 (genetic stan dard line), MD5lne and PD9364 cultivars from American have higher similarity wit h domestic cultivars. The reason may be that the parents of the domestic cultiva rs were mainly introduced from America. However, clusters of domestic cultivars are not all in accordance with their ecological regions, which may result from t he pedigree complexity of the cultivars. Meanwhile the genetic diversity of 36 c ultivars was investigated at phenotypic level with agronomic and fiber quality t raits in the field experiments in 1999 and 2000, and was measured by Euclidean d istance on the genotypes. Although grouping result of cluster analysis based on the Euclidean distance is similar than that of molecular data with a significant negative correlation of -0.3350 between the pair similarity coefficients and th e Euclidean distance, the subgroup classification of the two methods gives diffe rent result. The molecular markers can be effectively applied in classifiying cu ltivars within the group. The study provides useful information for the selectio n of parents in the development of cotton cultivars and hybrids as well.