Resumen de Genetic diversity in a Colombian bean (Phaseolus vulgaris L.) collection as assessed by phaseolin patterns and isoenzymatic markers

Gustavo Adolfo Ligarreto, César Ocampo

• The knowledge of genetic diversity patterns increase the efficiency of the conservation and the enrichment of the genetic resourses. This study allowed the discrimination of the existing genetic variability in a Colombian collection of shrub bean by phaseolin patterns and isoenzymatic markers. Bean seed proteins revelated that the phaseolin patterns types T and C are predominant in the Andean pool, type S in the Meso-American pool and type B in Colombian and Central American accessions, with a predominance of 81% of phaseolin T in the Andean pool, and 78% of phaseolin B in the Meso-American pool. The accessions of cultivated and wild beans showed variation in 10 of the studied enzymatic systems: ab-EST, GOT, ab-ACP, DIA, PRX, ASD, 6-PGDH, MDH, IDH and ME; and monomorphism in the PGI and PGM systems. The isozyme systems presented 19 bands of activity, of which 74% were polymorphic loci. Both in the Andean and Meso-American genetic pools, the loci Mdh-1, Mdh-2, b-Est-1, Skdh and Me exhibited polymorphisms. Single alleles in the Meso-American pool were found in 6-Pgdh-2103, Mdh-1100, Idh100, a-Est-1100, a-Est-2100, and Dia-195; and in the Andean pool, in 6-Pgdh-1100, and Acp-2100. For degree of domestication, the wild and cultivated accessions presented polymorphisms in 58 and 47% of the loci, respectively. The enzymatic relationship cluster analysis of the studied bean collection revealed three distinct groups of accessions; namely the Meso-American pool, including its cultivated and wild accessions; the Andean pool, which is mainly comprised of cultivated accessions, plus the wild DGD-626; and finally, featured by a high degree of enzymatic polymorphism and by the presence of the type I phaseolin, a third group that contains only a wild accession from the northern, Peruvian Andes.