利用ISSR标记分析烟草种质的遗传多样性

 【目的】分析烟草种质的遗传多样性水平，揭示不同烟草类型间的遗传关系，为充分发掘、利用种质提供依据。【方法】对包括不同烟草类型的119份种质进行了ISSR分析，估算其遗传相似系数，利用UPGMA法作聚类图。【结果】利用21个ISSR引物共扩增出672条带，全部为多态性带，其中116条为普通烟草特有带。普通烟草种质间的遗传相似系数变化范围为0.779～0.945，其中烤烟种质间遗传相似系数变化范围在0.812～0.933之间；不同烟草类型基本可聚为相应的亚类或小类，引进烤烟品种与国内品种并未聚为各自类别。普通烟草与其它烟草种间遗传相似系数较小；普通烟草与其假定祖先种N.sylvestris聚为一类，同为碧冬烟草亚属花烟草组的N.longiflora和N.plumbaginifolia聚为一类，聚类结果与种间遗传分化吻合。【结论】中国现有烤烟种质遗传多样性水平较低；为拓宽烤烟育成品种的遗传基础，应充分发掘野生烟草的遗传潜力。

Assessment of Genetic Diversity Among Tobacco Germplasms by ISSR Markers

[Objective] Assessing the genetic diversity among tobacco accessions and analyzing the genetic relationships among various types of tobacco in order to provide essential information for the exploration and utilization of tobacco germplasms. [Method] One hundred and nineteen tobacco accessions including various types of tobacco were used for ISSR analysis. The genetic similarity coefficients were estimated and cluster analysis was carried out using UPGMA method. [Result] 672 bands, all of which were polymorphic, were amplified using 21 ISSR primers. Out of them, 116 bands were specific for N. tabacum. Pairwise genetic similarity coefficients among accessions in N. tabacum ranged from 0.779 to 0.945. Among the flue-cured tobacco varieties, genetic similarity coefficients ranged from 0.812 to 0.933. The tobacco accessions could be clustered into different subgroups or classes according to the types of tobacco. The flue-cured tobacco accessions introduced from abroad were obviously not separated from the domestic accessions including landraces and varieties developed in China. There are low genetic similarity coefficients between the accessions in N. tabacum and other tobacco species. The species N. tabacum and its progenitor N. sylvestris were clustered into the same class, and N. longiflora and N. plumbaginifolia, both of them belong to the group Alatae of the subgenera Petunioides, were clustered into the same class. The results obtained in the ISSR dendrogram agreed with the presumed genetic differentiation. [Conclusion] There was a low genetic diversity among the flue-cured tobacco germplasms in China. In order to widen the genetic base of the flue-cured tobacco varieties, the genetic potentials in the wild tobacco should be explored.