Molecular diversity in genus Nicotiana as revealed by randomly amplified polymorphic DNA

61-66The genus Nicotiana consists of 64 recognized species of which, only 2 species, N. tabacum and N. rustica are cultivated extensively. Wild Nicotiana species are storehouses of genes for several diseases and pests, in addition to genes for several important phytochemicals and quality traits which are not present in cultivated varieties. Randomly amplified polymorphic DNA(RAPD) analysis was used to determine the degree of genetic variation in the genus Nicotiana and to develop species specific markers. 22 species and 2 interspecific hybrids were analyzed by using 18 decamer primers. Greater amount of genetic polymorphism exists among the wild species of genus Nicotiana (99.5%) as evidenced by the high degree of polymorphism in RAPD profiles. The pairwise similarity measures in the species of subgenus Rustica was 0.252 whereas in the subgenus Tabacum it was 0.189 suggesting that there was significant diversity amongst the species of these subgenera. In the species of subgenus Petunioides, the range of pairwise similarity measures was 0.128 to 0.941. The clustering pattern coincided with the traditional classification of Nicotiana species. All the primers generated specific bands in the various species. 36 species specific markers identified in the present study would be utilized in interspecific breeding programmes