Efficiency of RAPD and ISSR markers system in accessing genetic variation of rice bean (Vigna umbellata) landraces
Keywords: genetic diversity, ISSRs, landraces, rice bean, RAPDs, Vigna umbellate.
Present address: #Institute of Biochemical Sciences and Technology, Chaoyang University of Technology, 168 Gifeng E Road, Wufeng, Taichung 41349, Taiwan. Tel: 886 4 2332 3000, Fax: 886 4 2332 9898.
Vigna umbellata (Thunb.) Ohwi and Ohashi commonly known as rice bean or climbing mountain bean is under-exploited tropical legume. Genetic variation between 10 landraces of rice bean was evaluated using random amplified polymorphic DNA (RAPD) and inter simple sequence repeats (ISSR) markers. Among these markers, RAPD primers generated 987 amplification products of which 719 were polymorphic and ISSR markers produced 479 amplification products, out of which 296 were polymorphic. RAPD fingerprinting detected more polymorphic loci (70.30%) than the ISSR fingerprinting (61.79%). Mean PIC (polymorphic information content) for each of these marker systems (0.243 for RAPD and 0.203 for ISSR) suggested that both the marker systems were equally effective in determining polymorphisms. The dendrograms constructed using RAPD and ISSR marker systems were highly correlated with each other as revealed by high Mantel correlation (r = 0.95). Pair wise similarity index values ranged from 0.530 to 0.782 (RAPD), 0.608 and 0.862 (ISSR) and 0.559 to 0.777 (RAPD and ISSR) and mean similarity index value of 0.677, 0.729 and 0.694 for RAPD, ISSR and combined data respectively. RAPD and ISSR marker systems were found to be useful for the genetic diversity studies in V. umbellata andidentify variation within landraces.