Genetic variability of greater yam (Dioscorea alata I.) cultivar in Malaysia as revealed by RAPD markers

Investigation on genetic variability and relationship among 27 accessions of cultivated varieties (cultivars) of greater yam ( Dioscorea alata L. ) collected in Malaysia was conducted using random amplified polymorphic DNA (RAPD) markers. Eight primers were utilized for PCR-RAPD amplification which altogether produced 60 electrophoresis RAPD markers bands and 57 (95%) of them were polymorphic. Two-dimensional scatter diagram of the first two principal components (PCs) showed a wide dispersion among accessions indicating a diverse genetic variation of D. alata present in this country. Jaccard’s pair-wise similarity coefficient gave value of 0.67 (ranged 0.47 to 0.95) overall similarity among accessions indicating an infra-specific variation prevails in Malaysian D. alata. A dendrogram of accessions relationships constructed based on 57 RAPD markers using UPGMA clustering analysis has separated the accessions into four major cluster, A, B, C, and D. Accessions of white cultivars group, which were the most closely related accessions with an average similarity value of 0.74 among accessions, are mostly incorporated into the cluster A. Meanwhile accessions of purple cultivars group with an average similarity value 0.56 among accessions are genetically rather distant within and between the cultivars, and most of them linked in the clusters B, C and D. The RAPD technique used in this study was able to determine the genetic relationship among accessions and to distinguish various germplasms of D. alata in Malaysia. The analysis revealed that this region consists of large amount of D. alata genotypes resources that could probably be utilized for genetic selection and improvement of the crop.