Abstract
Angular leaf spot (ALS) and powdery mildew (PWM) are two important fungi diseases causing significant yield losses in common beans. In this study, a new genetic linkage map was constructed using single sequence repeats (SSRs) and single nucleotide polymorphisms (SNPs), in a segregating population derived from the AND 277 x SEA 5 cross, with 105 recombinant inbred lines. Phenotypic evaluations were performed in the greenhouse to identify quantitative trait loci (QTLs) associated with resistance by means of the composite interval mapping analysis. Four QTLs were identified for ALS resistance. The QTL ALS11AS, linked on the SNP BAR 5054, mapped on chromosome Pv11, showed the greatest effect (R2 = 26.5%) on ALS phenotypic variance. For PWM resistance, two QTLs were detected, PWM2AS and PWM11AS, on Pv2 and Pv11, explaining 7% and 66% of the phenotypic variation, respectively. Both QTLs on Pv11 were mapped on the same genomic region, suggesting that it is a pleiotropic region. The present study resulted in the identification of new markers closely linked to ALS and PWM QTLs, which can be used for marker-assisted selection, fine mapping and positional cloning.
Highlights
Common bean (Phaseolus vulgaris L.) represents an important source of protein in the human diet, especially in developing countries (Gepts et al, 2008)
SEA 5 belongs to the Mesoamerican gene pool and it is susceptible to angular leaf spot
A total of 150 (46%) single sequence repeats (SSRs) were polymorphic between the AS parents
Summary
Common bean (Phaseolus vulgaris L.) represents an important source of protein in the human diet, especially in developing countries (Gepts et al, 2008). Phaeoisariopsis griseola (Sacc.) Ferraris) (Crous et al, 2006) severely reduces common bean yield in tropical and subtropical regions. This disease occurs in more than 60 countries including Brazil, and depending on the environmental and management conditions the losses can reach up to 80% (Schwartz et al, 1982; Jesus Júnior et al, 2001). This disease causes necrotic lesions in the leaves, pods, and stems. Lesions may appear on the seeds, resulting in losses in grain productivity and quality
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