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Genetic Characterization of Differential Reactions Among Host Group 3 Common Bean Cultivars to NL-3 K Strain of Bean common mosaic necrosis virus

First, third, and fifth authors: Department of Plant, Soil, and Entomological Sciences, University of Idaho, Kimberly Research and Extension Center, 3793 N. 3600 E., Kimberly 83341; second author: Vegetable and Forage Crop Production Research, U.S. Department of Agriculture-Agricultural Research Service, 24106 N. Bunn Rd., Prosser, WA 99350; and fourth author: Department of Horticulture, Oregon State University, Corvallis 97331

A previously unrecognized recessive resistance gene (or allele) was identified in three host group (HG) 3 common bean (Phaseolus vulgaris) cvs. Olathe, Victor, and UI 37, based on genetic analysis of plants from five populations screened with the NL-3 K strain of Bean common mosaic necrosis virus (BCMNV). The gene (or allele) was associated with resistance to leaf stunting and deformity and reduction in plant height. The gene (or allele) provides similar, but slightly better resistance than the bc-1² gene that is characteristic of HG 3 cultivars. Traditional HG 3 cultivars like Redlands Greenleaf B with bc-1² are susceptible to NL-3 K, whereas this newly identified gene (or allele) conditions resistance to NL-3 K. Other slight variations in disease reaction pattern to a wide array of bean common mosaic (BCM)-inducing strains were noted among HG 3 differentials, indicating that additional resistance to BCM exists in common bean that remains to be exploited. To gauge the full breeding value of this newly identified gene (or allele), allelism tests with existing genes, namely bc-1², and further characterization of responses to all Bean common mosaic virus (BCMV) and BCMNV strains need to be conducted. Meanwhile, breeders should consider introgressing this more effective gene (or allele) into susceptible cultivars while plant pathologists continue to decipher the genetic variability present among HG 3 differential cultivars.

Additional keyword: potyvirus.