Identification of genomic regions for anthracnose resistance in the Andean mapping population of common bean derived from a cross of genotypes Lusaka and Mwezi Moja.

Abstract

Anthracnose (ANTH), caused by Colletotrichum lindemuthianum, is a major disease of common bean (Phaseolus vulgaris L.) and an important constraint to bean production in Zambia and other countries. The high genetic variability of the pathogen and the occurrence of numerous physiological races complicate the development of varieties with durable resistance. The objectives of this study were to (i) characterize isolates of C. lindemuthianum collected from Zambia into physiological races and (ii) identify genomic regions associated with resistance to anthracnose in a recombinant inbred line (RIL) population. Four isolates collected from two major bean-producing districts of Zambia were characterized as races 7, 15, 17, and 291 using standard differential cultivars. A population of 110 F_5:6 RILs derived from a cross between Mwezi Moja, a Kenyan variety with purple speckled seed color, and Lusaka, a Zambian landrace with manteca yellow seed color, was evaluated for resistance to the four races and one uncharacterized isolate A23-13. RIL LM145 exhibited high resistance to all four races and the uncharacterized isolate A23-13. Genotyping of the population with the BARCBean12K SNP array followed by composite interval mapping identified four QTL: ANT1.1^LM, ANT2.1^LM, ANT4.1^LM, and ANT10.1^LM. ANT1.1^LM explained 60.5% and 57.7% of the phenotypic for resistance to race 17 and A23-13, respectively; ANT2.1^LM explained 4.2% for A23-13; ANT4.1^LM explained 75.5% for race 291; and ANT10.1^LM explained 18.9% and 25.9% for races 7 and 15, respectively. ANT1.1^LM and ANT4.1^LM co-localized with the known resistance loci Co-1 and Co-3, respectively. Pyramiding of major resistance loci identified in this study may contribute to broader resistance to diverse races of C. lindemuthianum.