A source of resistance to bacterial wilt in the common bean (Phaseolus vulgaris) in Iran.
Bacterial wilt, which is caused by Curtobacterium flaccumfaciens pv. flaccumfaciens (Cff), has recently emerged in common bean, lima bean, and cowpea plants in the provinces of East Azerbaijan and Markazi in the northwestern and central regions of Iran, respectively. Because the development of wilt-resistant common bean cultivars is the most cost-effective and lasting method for controlling the disease, this study was conducted to evaluate the common bean germplasms provided by the Khomein Bean Research Station (Khomein County, Markazi Province) for their resistance to Cff. Forty-three common bean genotypes were used in this study, and the node infiltration method was used to inoculate common bean seedlings at the V3 stage of development. Based on the disease severity index (DSI) values, the brown pinto ks21186 line, the red pinto Chili landrace, and the brown pinto ks21193 line were identified as resistant to the highly virulent yellow variant of the bacterial wilt pathogen Cffcb124 strain (DSI: 0.85, 0.9 and 0.92 out of 4.0, respectively). Among the three resistant germplasms, the ks21186 line was also resistant to other strains of the pathogen isolated from cowpea (Cffcw13 and Cffcw11), lima bean (Cffcb122), and common bean (Cffcb145 and Cffcb125) (mean DSI: 0.77). The mean DSI values of the ks21193 line and the Chili landrace were higher than the DSI threshold, below which indicates resistance (DSI: 1.14 and 1.22, respectively). This study concludes that a new bacterial wilt-resistant line (ks21186) exists among the common bean varieties at the Khomein Bean Research Station of Iran.