Release of UPR-Mp-37 and UPR-Mp-48 white common bean germplasm with improved resistance to ashy stem blight

White common bean (Phaseolus vulgaris L.) breeding lines (BL) UPR-Mp-37 (Reg. no. GP-315, PI 703030), and UPR-Mp-48 (Reg. no. GP-316, PI 703031) with improved resistance to ashy stem blight [caused by Macrophomina phaseolina (Tassi) Goidanich] were developed at the University of Puerto Rico. Both these BL had lower severity (mean scores of 4.1-4.7) to PRI21 M. phaseolina isolate compared with white common bean genotypes 'Bella', 'Beniquez', NY6020-4, and 'Verano' that had a susceptible response (scores >7.0). UPR-Mp-37 was selected from the cross NY6020-4/A 195//SEA 5 while UPR-Mp-48 was derived from the common bean population BAT 477/NY6020-4/PRA154. UPR-Mp-37 has an indeterminate growth habit type III, initiates flowering at 30 days after planting, reaches harvesting maturity at 89 days, and has an average weight of 27.4 g per 100 seed. UPR-Mp-48 has a determinate growth habit type I, initiates flowering and matures at 33 and 85 days after planting, respectively, and has an average weight of 29.6 g per 100 seed. Both BL had over 800 kg ha-1 seed yields in Isabela, Puerto Rico. The resistance of UPR-Mp-37 and UPR-Mp-48 BL can be introgressed into susceptible white beans to reduce the disease severity.

Automated summary

White common bean breeding lines UPR-Mp-37 and UPR-Mp-48 with improved resistance to ashy stem blight were developed at the University of Puerto Rico. These breeding lines exhibited lower disease severity compared to susceptible genotypes and their resistance can be introgressed into susceptible white beans.