GENETIC DIVERSITY IN CHEWING TOBACCO GROWN IN GUJARAT AND WEST BENGAL AS REVEALED BY RAPD AND SSR MARKERS

Abstract

Genetic diversity among released varieties of chewing tobacco belonging to Nicotiana tabacum and Nicotiana rustica grown in Gujarat and West Bengal states was studied using randomly amplified polymorphic DNA (RAPD) and simple sequence repeat (SSR) markers. Seventeen out of 19 RAPD primers amplified 82 fragments of which 70 (85.35%) were polymorphic. Twenty SSR primers amplified 81 fragments of which 46 (56.79%) were polymorphic. The extent of pair-wise similarity ranged from 0.29 to 0.93 with an average of 0.61 in RAPD, in contrast to a range of 0.20 to 0.91 with a mean of 0.55 in SSR markers. The formation of two clusters in dendrogram by both the markers was similar where the three varieties of N. tabacum were grouped togather in cluster 1 and the 7 varieties of N. rustica were grouped in cluster 2 based on species specificity. The cluster formation was based on species and sub-cluster formation was based on parentage. The genetic variation in chewing tobacco varieties of N. tabacum grown in Gujarat was very narrow. In N. rustica cultivars, the genetic distance was 12 to 52% and 11 to 54% in RAPD and SSR markers respectively indicating a large genetic variability. SSR markers were found more efficient than RAPD in parentage estimation of chewing tobacco cultivars and could be used for development of markers for various traits