Release of Andean abiotic‐resilient common bean germplasm

Abstract

Andean abiotic‐resilient (AAR) common bean ( Phaseolus vulgaris L.) germplasm lines AAR1 to AAR7 were developed through an international bulk breeding effort to improve abiotic stress tolerance and combine it with disease resistance by increasing genetic richness. These lines represent unique sources of climate resilience selected by the USDA‐ARS in Puerto Rico, the Agriculture Research Council in South Africa, and the USDA‐ARS in Washington State, with subsequent selection in Puerto Rico for tolerance against multiple stresses, including drought, high ambient temperature, low nitrogen soil fertility, and root rot. The resulting seven lines all possess drought tolerance and varying levels of heat tolerance. AAR1 (Reg. No. GP‐331, PI 708105; cream‐colored seed type), AAR4 [Reg. No. GP‐334, PI 708108; purple/blue speckled (kablanketi) seed type], AAR5 (Reg. No. GP‐335, PI 708109; light red kidney seed type), and AAR6 (Reg. No. GP‐336, PI 708110; dark red kidney seed type) exhibit moderate heat tolerance, while AAR2 (Reg. No. GP‐332, PI 708106) and AAR3 (Reg. No. GP‐333, PI 708107; light red kidney seed types) and AAR7 (Reg. No. GP‐337, PI 708111; pink with dark stripes seed type) possess moderately high levels of heat tolerance. In addition, AAR2, AAR3, AAR4, and AAR6 showed moderate resistance to ashy stem blight [caused by Macrophomina phaseolina (Tassi) Goidanich], while AAR6 and AAR7 showed some tolerance to the root rot complex and low nitrogen soil fertility. All seven lines exhibit early flowering and maturity, six show a type I compact determinate bush growth habit, one is an indeterminate type II, and all have a rapid and definitive switch from vegetative to reproductive development. These characteristics associated with escape from heat stress are also associated with resistance mechanisms in warmer, drier climates.