RAPD and ISSR fingerprints as useful genetic markers for analysis of genetic diversity, varietal identification, and phylogenetic relationships in peanut (Arachis hypogaea) cultivars and wild species

Twenty-one random and 29 SSR primers were used to assess genetic variation and interrelationships among subspecies and botanical varieties of cultivat ed peanut, Arachis hypogaea (2n = 4x = 40), and phylogenetic relationships among cultivated peanut and wild species of the genus Arachis. In contrast with the previous generalization that peanut accessions lack genetic variat ion, both random and SSR primers revealed 42.7 and 54.4% polymorphism, resp ectively, among 220 and 124 genetic loci amplified from 13 accessions. More over, the dendrograms based on RAPD, ISSR, and RAPD + ISSR data precisely o rganized the five botanical varieties of the two subspecies into five clust ers. One SSR primer was identified that could distinguish all the accession s analysed within a variety. Although the polymorphic index content varied from 0.1 to 0.5 for both ISSR and RAPD markers, primer index values were su bstantially higher for RAPD primers (0.35-4.65) than for SSR primers (0.35- 1.73). It was possible to identify accessions, particularly those of diverg ent origins, by RAPD and (or) ISSR fingerprints. Based on these results, ma rker-based genetic improvement in A. hypogaea appears possible. None of the 486 RAPD and 330 ISSR amplification products were found to be commonly sha red among 13 species of section Arachis and one species each of sections He teranthae, Rhizomatosae, and Procumbentes. Dendrograms constructed from RAP D, ISSR, and RAPD + ISSR data showed overall similar topologies. They could be resolved into four groups corresponding to the species grouped in four taxonomic sections. The present results strongly support the view that Arac his monticola (2n = 4x = 40) and A. hypogaea are very closely related, and indicate that A. villosa and A. ipaensis are the diploid wild progenitors o f these tetraploid species.