利用RAPD分子标记技术对棉属24个种进行了种质资源遗传多样性研究，并用棉属近缘植物杨叶肖槿为参考对照，旨在从DNA分子水平上进行亲缘关系鉴定和系统分类。在40个RAPD引物中筛选出多态性高的引物26条，多态性条带比率为2l.0%。使用NTSYS-pc（Version 2.00）软件，及Jaccard’s相似系数UPGMA法进行聚类，表明材料之间存在较大的遗传多样性，对20个二倍体棉种进行遗传相似系数比较，说明旱地棉和绿顶棉、澳洲棉之间的亲缘关系最远；对异源四倍体棉种与A和D染色体组棉种的遗传相似系数比较结果表明，异源四倍体棉种与A染色体组中的草棉和亚洲棉，相似系数都较高，说明在四倍体棉种演化过程中草棉和亚洲棉起的作用是等比例的；异源四倍体棉种与雷蒙地氏棉的遗传相似系数显著高于与其他参试的D染色体组棉种，证明异源四倍体棉种的D染色体组供体种为雷蒙地氏棉，并支持异源四倍体棉种单系统发育起源学说，A染色体亚组的草棉或亚洲棉与D染色体亚组的雷蒙地氏棉两者杂交和染色体加倍后形成原始的异源四倍体棉种，并随着地理和遗传的趋异而分化形成不同的四倍体棉种；RAPD分子标记聚类结果与传统的分类结果基本相符，说明RAPD分子标记资料可用于棉属植物的分类和系统发育研究。
There are 51 species in Gossypium including 5 tetraploid species (AD genome, 2n=52) and 46 diploid species which belong to the genome A, B, C, D, E, F, G, and K, respectively. Among them, there are 4 cultivated species including 2 tetraploid species, G. hirsutum and G. barbadense, and 2 diploid species belonging to genome A, G. arboreum and G. herbaceum. All the 5 tetraploid cotton species were testified to be AD allopolyploids, which was developed from the hybridization between two diploid species related to the genome A and genome D. Since their parental genome groups exist in diploid form, the question “how allopolyploid cotton formed” has stimulated discussion for more than 50 years. Furthermore, the species in Gossypium genus represent a vast resource of genetic multiplicity for the improvement of cultivated cotton. Research on genetic diversity and phylogenetic relationships among cultivated and wild cotton species is necessary for better understanding of cotton evolution. In order to determine the genetic diversity and relationships within a diverse collection in genus of Gossypium, 24 cotton species in gossypium including 20 diploid species representing 7 basic genome groups and 4 AD allotetraploid cotton accessions were assessed by RAPD, using their relative plant, T. populnea, as contrast. 26 of 40 RAPD primers were polymorphic, with the percentage of polymorphic bands of 21.0%，and the dendrograms were constructed by the Unweighted Pair Group Method of Arithmetic Average （UPGMA） based on Jaccard，s genetic similarity coefficients using the NTSYS-pc（Version 2.00）. The results showed that there was an obvious genetic diversity among 25 species. Among 20 diploid cotton species, the genetic similarity coefficient between G. aridum and G. capitis-viridis was the lowest, so did between G. aridum and G. australe. Therefore, the genetic relationship between G. aridum and G. capitis-viridis / G. australe was the farthest. Genetic similarity coefficients between allotetraploid and the diploid species belonging to genome A and genome D showed that the A-genome donor was much similar to the present-day G. herbaceum and G.arboretum，and they played an equal role on the course of formation of allotetraploid cotton species. The highest genetic similarity coefficient between allotetraploid species and G. raimondii indicated that G. raimondii was the possible D genome donor of allotetraploid cotton species. According to the results of this experiment and others, the ancient allotetraploid cotton species might be formed by hybridization and chromosome doubling between the species related to G. arboreum or G. herbaceum and G. raimondii, then different allotetraploid cotton species were appeared by further geographical and genetical isolation and separating differentiation, which supported the evolution theory of sole origin of allotetraploid cotton species. In addition, this result illuminated that the RAPD is an useful method in study of genetic diversity and pedigree classification of cotton resources at the genomic level, and the clustering analysis based on RAPD data was coincident with the results obtained from the traditional classification.
全 文 ：