Abstract:

Genetic diversity and relationships of tobacco is a basic part of the research in breeding, origin and evolvement of tobacco. Sixteen primers were selected from 70 ISSR primers, and 309 DNA fragments were amplified from 30 samples including 3 wild species and 1 cultivated species. Of which, 288 fragments were polymorphic (percentage of polymorphic bands was 93.20%), and the average number of DNA bands was 19.31 per primer. The genetic similarity among all species ranged from 0.26 to 0.96, and that among 3 wild species N.glutinosa, N.suaveolens and N.Gossei was 0.29–0.52, while among cultivars was 0.54–0.96, which was comparatively higher. This indicated that the genetic basis was comparatively narrow among the cultivars, except Bailei 21, Taiyan 7 and other materials. The cluster analysis based on ISSR markers showed that the 3 wild species were genetically different from the other 27 cultivars at the level of D=0.475, and the 30 tobacco accessions could be classified into two groups, three classes and six types at the level of D=0.776. The results indicated that ISSR technique has better stability than RAPD and is useful in revealing the genetic diversity and genetic relationships among tobacco species, providing a scientific basis for genetic research and tobacco breeding, as well as for gene cloning of plant germplasm and parents selection in constructing genetic linkage map of tobacco.

Key words: Tobacco, ISSR, Genetic diversity, Genetic relatives