Efficiency of a recurrent selection method to achieve resistance of common beans to Pseudocercospora griseola in a short period

Abstract

The angular leaf spot (ALS), caused by the fungus Pseudocercospora griseola, is one of the most notable diseases of common beans (Phaseolus vulgaris). The most effective strategy to control ALS is quantitative disease resistance provided by major and minor genes. One breeding strategy for obtaining lines with durable resistance to P. griseola is a recurrent selection that aims to gradually assemble favorable alleles. In this study, common beans were artificially inoculated with P. griseola and grown in a greenhouse under a recurrent selection program that aims to accelerate the breeding cycle and assimilate resistant conferring genes per generation. From the initial population, three cycles of evaluation, selection, and intercross were carried out in a greenhouse and the most resistant plants were phenotypically selected. Plants at the V2 stage were inoculated with an isolate of P. griseola, race 63-63. Selected plants were transplanted into pots and intercrossed to reap the next cycle of selection. Progenies obtained from the base population (C0) and subsequent cycles (CI, CII, and CIII) were assessed for the degree of the symptoms for ALS under greenhouse and field conditions. The rate of genetic progress per breeding cycle was - 14.8% and - 5.3% for the plants grown in greenhouse and field, respectively. Artificial inoculation with P. griseola allowed three recurrent selection cycles per year, signifying a promising method to obtain ALS-resistant common bean lines in a short period.