RAPD markers for genetic diversity study among Indian cotton cultivars

The present study was undertaken with RAPD markers for genetic diversity estimation in 59 cotton cultivars belonging to four cultivated species of cotton. The selected eighteen RAPD primers produced a total of 251 amplicons, which generated 97.21% polymorphism. The number of amplification products ranged from 7 to 24 for different primers, whereas per cent genetic similarity for the studied primers ranged from 42 to 79. Among 59 cotton cultivars, 36% genetic diversity was observed. In 41 Gossypium hirsutum cultivars included in the study, the average genetic similarity was 74%. More genetic diversity was observed in diploid than in tetraploid cotton cultivars. UPGMA cluster analysis placed tetraploid cotton cultivars into two distinct clusters that are in agreement with the traditional taxonomic arrangement of these cultivars into G. hirsutum and G. barbadense. Analysis of molecular variance in G. hirsutum cultivars revealed that most of the variance could be attributed to within breeding-centre variance. All the cultivars could be discriminated from one another based on the combined profiles for eighteen oligonucleotide primers. A negative correlation between average genetic similarity for a primer and the number of cultivars; identified by it was observed. Genetically distinct cultivars were identified that could be potentially important sources of germplasm for further cotton improvement in the country.