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Characterization of a Bean common mosaic virus isolate from lima bean (Phaseolus lunatus)

Xue Feng: University of Idaho EPPN Department

<div>Lima bean (<em>Phaseolus lunatus </em>L.) is a popular cultivated legume vegetable grown for dry bean or canned bean production in the United States. Viruses affecting lima bean have not yet been well studied. In 2016, two symptomatic <em>P. lunatus</em> plants exhibiting mosaic, vein banding, and growth retardation were collected in a public garden in Honolulu, HI. A potyvirus-specific ELISA (Agdia, Elkhart, IN) was initially used to identify potyvirus infection in the two samples. Sequencing of RT-PCR products generated using the universal potyvirus primer set NIb2F and NIb3R and virus-specific ELISA confirmed both samples as positive for <em>Bean common mosaic virus</em> (BCMV). The samples were subjected to biological characterization on a panel of 11 differential cultivars of common bean (<em>Phaseolus vulgaris</em>), and to molecular characterization through whole genome sequencing. Both samples were found to contain nearly identical BCMV sequences, named BCMV-A1, which were 93% identical to some BCMV isolates from China. BCMV-A1 induced an unusually severe systemic necrosis in cultivar ‘Dubbele Witte’ which could result in plant death in 10-15 dpi, and was able to partially overcome resistance genes <em>bc-1</em> and <em>bc-2</em> in common bean. Phylogenetic analysis of the BCMV-A1 sequence, and distinct biological reactions in common bean differentials suggested that isolate A1 represents a novel strain of BCMV.</div>