Relationships and utilization of arachis germplasm in peanut improvement

by 1973- Milla, Susana Rita

Cultivated peanut, Arachis hypogaea L., is a tetraploid (2n = 4x = 40) species considered to be of allopolyploid origin. Its closest relatives are the diploid (2n = 2x = 20) annual and perennial species included with it in section Arachis. Species in section Arachis represent an important source of novel alleles for the improvement of cultivated peanut. The AFLP technique was used to determine intra- and inter-specific relationships among and within 108 accessions of 26 species of this section. A total of 1328 fragments were generated with 8 primer combinations. From those, 239 unambiguous bands ranging in size from 65 to 760 bp were scored as binary data. Genetic distances among accessions ranged from 0 to 0.50. Average distances among diploid species (0.30) were much higher than that detected between tetraploid species (0.05). Cluster analysis using different methods and principal component analysis were performed. The resulting grouping of accessions and species supports previous taxonomic classifications and genome designations. Based on genetic distances and cluster analysis, “A” genome accessions KG 30029 (A. helodes), and KSSc 36009 (A. simpsonii), and “B” genome accession KGBSPSc 30076 (A. ipaensis) were the most closely related to both A. hypogaea and A. monticola suggesting their involvement in the evolution of the tetraploid species. 20