Genetic diversity of saline rice cultivars based on RAPD markers

RAPD markers were used to evaluate genetic relationships in 20 cultivars of saline tolerant rice including few tolerant varieties. Twenty primers generated 207 highly reproducible and discernible loci, among which 160 were polymorphic. Percentage of polymorphism varied from 50 to 100 with an average of 74.8. Two primers, OPBA-03 and OPBC-10 showed 100 percent polymorphism among the accessions studied. A relatively high genetic diversity was detected among all the samples with the similarity coefficient value ranging from 0.45 to 1.00. The uweighed pair group method with arithmetic averages (UPGMA) dendrogram clustered 20 accessions in four clusters at 0.75 coefficient level. Principal coordinate analysis (PCA) further indicated that the genetic diversity of saline rice cultivars was presented by a clustered distribution pattern. Thus, the results from the UPGMA which grouped the accessions into 4 clusters lies more or less on par to the results of PCA. The cluster II and IV consisted of 6 and 10 accessions, respectively and cluster I and III consisted of 1 and 3 accessions, respectively. The similarity co-efficient was maximum between IR 61920-3B-22-2-1 and IR 42 (1.00) indicating less divergence among them. Lower similarity coefficient indices were observed between IR 61920-3B-22-2-1 and HP 3319-2WH-6-3-1-1-3 (0.26), indicating more divergence. Neither the UPGMA dendrogram analysis nor the PCA exhibited strict relationship with geographic distribution for the characters studied.