Host plant resistance to bean common mosaic necrosis virus among snap bean cultivars in Kenya

Abstract

Snap bean production in Kenya is constrained by many pests and diseases, including the bean common mosaic virus (BCMV) and bean common mosaic necrosis virus (BCMNV). The occurrence of the dominant I gene in many snap bean cultivars has provided a measure of control over BCMV but the BCMNV overcomes this resistance. The current study aimed to screen a collection of locally grown snap bean commercial cultivars, landraces, breeding lines, and dry bean cultivars for the expression of resistance against BCMNV under both field and greenhouse conditions. The results showed that the evaluated snap bean cultivars were susceptible to BCMNV. The reactions of the genotypes to BCMNV varied from top, vein and local necrosis, mosaics, mottling, deformed leaves to stunted growth. Positive infection was confirmed through enzyme linked immunosorbent assays. The dry bean cultivars, which were used as resistant checks can be explored as sources of resistance to BCMNV in future breeding programs. Molecular analysis showed that the SW13 and elF4E markers were reliable in confirming the presence or absence of the dominant I gene and the recessive bc-3 gene, respectively. These molecular markers are useful in marker-assisted breeding programs.