Abstract:
Twenty two species representing three subgenera of the genus Nicotiana and two interspecific
hybrids were analysed by AFLP. A total of 554 bands were amplified by 6 primer pairs, of
which 541 (97.65%) were polymorphic and 13 (2.34%) monomorphic. The primer combination
E-AAC/M-CTG gave the highest polymorphic information content (PIC) across all species,
whereas E-AAG/M-CAC gave the lowest PIC score. A total of 59 species specific markers were
generated, of which 54, 4 and 1 were specific to subgenera Petunioides, Tabacum and Rustica
respectively. The pair-wise similarity measure in the species of subgenus Rustica was 0.35
whereas it was 0.29-0.50 in subgenus Tabacum, suggesting that there was significant diversity
among the species of these subgenera. In the species of subgenus Petunioides, the range of
pair-wise similarity measure was 0.25 to 0.95. The high genetic similarity (95%) was due
close relationship among the species belonging to the sections Rependae and Trigonophyllae.
Sub-grouping of the species within the main clusters of dendrogram was largely based on the
chromosome number. AFLP was found efficient in determining the extent of interspecific genetic
diversity existing in genus Nicotiana. The subgenus and species specific AFLP markers identified
in this study would be useful in introgression breeding programs of tobacco. N. tabacum shared
174/198 AFLP fragments with the two progenitor species, thus providing molecular evidence
that these two wild species contributed genetic information to N. tabacum
