Sensitivity to,and metabolism of,phaseollin in relation to the pathogenicity of different isolates of Botrytis cinerea to bean (Phaseolus vulgaris)

The pathogenicity of five isolates ofBotrytis cinerea to bean (Phaseolus vulgaris) was compared with their sensitivity to the phytoalexin phaseollin and their ability to metabolize phaseollin. Three of the five isolates were pathogenic to bean, as they formed spreading lesions on bean leaves; the other two isolates were considered nonpathogenic to bean, since they produced lesions limited in size or no lesions at all. The isolates were about equally sensitive to phaseollin, except for one nonpathogenic strain which was more sensitive than the other ones to higher concentrations of phaseollin. The three pathogenic isolates metabolized phaseollin to 6a-hydroxyphaseollin readily in shake cultures containing 9 μg phaseollin/ml, while nonpathogenic isolates were not able, or less able, to do so.