Figure 3

Marker-trait association of the Hbs-1 locus. A marker-trait association of the Hbs-1 locus was analyzed using thirteen cowpea genotypes which differ in their response to heat-induced browning of seed coats phenotype. IT93K-503-1, IT84S-2246, IT93K-2046, TVu-4552 and TVx-3236, TVu-53 and TVu-15315 were positive for the heat-induced browning phenotype and are referred to as Hbs. TVu-14676, CB5, CB27, CB46, 524B and Bambey 21 are negative for the heat-induced browning phenotype and are referred to as hbs. The most significant region of the Hbs-1 locus spanned from 45.27 cM to 47.18 cM on the cowpea consensus genetic map linkage group 5. SNP markers 1_0032 and 1_1128 alleles co-segregated with the positive (Hbs) and negative (hbs) genotypes. The Hbs-1 positive genotypes were associated with the adenine nucleotide (color-coded green) at the 1_0032 locus, while hbs-1 negative genotypes were associated with the guanine nucleotide (color-coded red). The adenine/guanine SNP in marker 1_0032 is position 469 of cowpea unigene 5294 which was annotated as an AMP dependant ligase/synthetase and can be viewed in HarvEST:Cowpea. At the 1_1128 locus, the Hbs-1 positive genotypes were associated with the thymine nucleotide (color-coded blue) while the hbs-1-negative genotypes were associated with the adenine nucleotide (color-coded green). The thymine/adenine SNP in marker 1_1128 is position 950 of cowpea unigene 4874, which was annotated as an ubiquitin-protein ligase and can be viewed in HarvEST: Cowpea.