Abstract
Quantitative measurements, using thin layer chromatography plus ultraviolet spectophotometry and gas-liquid chromatography, have shown that phaseollin accumulation was limited to infected tissue which was visibly brown. Phaseollin accumulated much earlier following infection by an incompatible race, which caused hypersensitivity, than by a compatible race which eventually caused lesions to form. Basal phaseollin metabolism was not affected by the extensive intracellular growth of compatible races of Colletotrichum lindemuthianum which continued for several days before host cells collapsed and became brown. Concentrations of 71 to 147 μg phaseollin/g fresh weight excised hypersensitive tissue were detected. However, calculations suggest that phaseollin concentrations in hypersensitive cells might be many-fold higher than these values. Germination of all races was equally sensitive to low concentrations of phaseollin (less than 10 μg/ml). Although germ-tube growth was also inhibited by small amounts of phaseollin, mycelial growth was less sensitive and experiments indicated that phaseollin was metabolized by hyphae in liquid culture. The production, cellular distribution and concentration, and fungitoxicity of phaseollin are discussed in relation to the importance of phaseollin in restricting hyphal growth during hypersensitive reactions.
Published Version
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