Effect of phleichrome produced by the timothy leaf spot fungus, Cladosporium phlei on the invertases from the host leaves.

Abstract

Phleichrome was isolated from the culture of Cladosporium phlei and its actions were examined on the invertases from the leaves of timothy, Phleum pratense. Phototransformed phleichrome was almost identical with the pigment from the diseased spots in some properties, suggesting that phleichrome may be a pathotoxin. Susceptibility and resistibility of SH requiring and non-requiring invertases, respectively, to phleichrome were demonstrated as was the case for p-chloromercuribenzoate. Its inhibitory action on this enzyme was partially neutralized by the addition of dithiothreitol or L-cysteine. Exposed to visible light (474nm), phleichrome showed less inhibitory action on this enzyme. The inhibition of SH enzymes by this toxin is assumed to be a factor to incite the timothy leaf spot disease.