国内外57份棉花种质资源的遗传多样性研究

Genetic Diversity of 57 Cotton Germplasm Resources from China and Overseas

通过表型聚类和SSR分子标记聚类研究了国内外57份棉花种质的遗传多样性。结果表明，品种间遗传相似系数在0．45—5．56之间，说明供试种质具有较大的遗传变异。根据UPGMA法构建聚类树状图，基于产量性状的聚类，在平均遗传距离4．0水平上，可将57份材料分为3类，第一类衣分最高，平均值达38．22％，单株皮棉产量也达到最高，平均值为29．35g；第二类的籽指、单株籽棉产量和单株铃数最高，其平均值达12．05g、76．73g和23．60个；第三类铃重最大，为5．54g。基于纤维品质性状的聚类，在阈值3．96时也可分为3类，第一类整齐度和马克隆值最高，平均值分别为48．04％和4．36；第二类的纤维长度及伸长率最大，平均值分别为31．57mm和7．11％，第三类的比强度最大，为36．18eN／tex。基于SSR分子标记的聚类，57份材料也可聚为三大类。不同聚类方法的结果间存在一定差异，可能与不同方法反映的多态性水平不同。各种聚类结果都表明，同一国家的品种遗传差异较小，国家间品种差异较大，但也存在明显的相互渗透，多数品种没有表现出明显的地域差异。

The genetic diversity of 57 cotton germplasms from China, USA and Australia was studied by clustering based on phenotypic and SSR molecular marker data. The results showed that the genetic similarity coeglcient among varieties ranged from 0. 45 to 5.56 indicating a relatively large genetic variation. The tree diagram of UPGMA clustering based on yield traits at the average genetic distance level of 4. 0 indicated that 57 cotton germplasms were divided into three categories, in which, the first category had the highest lint percentage and lint yield per plant with the mean value of 38. 22% and 29. 35 g respectively; the second category possessed the highest seed index, seed cotton per plant and boll number per plant, whose mean values were 12. 05 g, 76. 73 g and 23.60 respectively; the third category had the highest boll weight up to 5.54 g. The result of clustering based on fiber quality traits also showed three categories, and the first category had higher fiber uniformity ratio and fiber micronaire reading, with the mean values of 48.04% and 4. 36 respectively; the second category possessed higher fiber span length and fiber elongation with the mean values of 31.57 mm and 7. 11% respectively; the third category had higher average fiber strength of 36. 18 eN/tex. By clustering based on SSR markers, the 57 germplasms could also be clustered into three categories. Some differences were found among results of different clustering methods, which might be related to the different genetie diversity levels of different phenotypic traits and molecular genotypes used in this study. All clustering results indicated that there were relatively smaller and larger genetic diversity among varieties from one country and from different countries respectively. But there was obvious mutual penetration between countries. Only a few varieties showed significant geographical differences.