Divergência genética entre linhagens africanas de feijão-caupi (Vigna unguiculata (L.) Walp.) através de caracterização morfoagronômica e molecular

Abstract

The genetic divergence assessement provides important information for breeding programs. In the present study, the genetic diversity among lines from Embrapa Mid-North’s Cowpea Germoplasm Active Bank (BAG) was evaluated morphoagronomically 57 cowpea lines. The experiment was carried out in august/2009. Field plots were arranged in a randomized block design with three replicates containing 57 of cowpea lines. The lines The behaviour of accessions was evaluated by univariate and multivariate analyses, with dissimilarities obtained by the generalized distance of Mahalanobis (D2) and the grouping technique by the UPGMA method. The genetic distances between pairs of lines ranged from 1.21 to 221.35. The lines IT89KD-245 indicated as the most divergent should through quantitative characteristics be included as parental in intercross programs. Were formed four groups by UPGMA method. The characteristics which most contributed to genetic divergence were total weight of a hundred grain (49.7 %), length of the pod (16.7 %), length of the grain (12.0 %) and number of grains per pod (9.7 %). The lines were studied to verify the efficiency of dissimilarity measures and to discriminate genotypes, based on 26 multicategoric variables. The lines IT98K-491-4 e IT00K- 898-5; IT99K-494-6 e IT98K-131-2; IT99K-718-6 e IT89KD-245; IT99K-494-6 e IT97K-568-14 e IT98K-128-3 e IT99K-718-6 confirming these genotypes as the most similar among the evaluated for quality characteristics. Based in these characteristics the lines formed eleven groups by Tocher method. Through analyzing morphoagronomical traits were possible identify genetic divergence among lines studies. Were evaluated by SSR marker 32 african lines cowpea using 10 SSR locos that generating 24 polymorphic bands. The data matrix was analyzed by UPGMA (Unweighted Pair Group using mathematical averages) using NTSYs 2.1 program. The accessions were distributed in eight clusters, and the lines IT00K-1217-2 e IT00K-718-6; IT99K-316-2, IT98K-205-8 e IT98K-506-1; IT98K-1111-1, IT00K-491-7, IT93K-625 e IT96D-610; IT97K-568-18 e T89KD-260; IT99K-1060, IT00K-1263-2 e IT00K-1263-1, presented high similarity to each other. The average polymorphism information content (PIC) was 0.2552, in the range of 0.0587 - 0.4188 for VM36 and VM39 locos. The lines IT87D-1627 was confirmed as the most divergent of all, could be use as parental in crosses for purposes. The SSR results of the underscore their potential in elucidating patterns of germplasm diversity of cowpea from Embrapa Mid- North’s BAG.