Purification and structural determination of a phytotoxic substance from Exserohilum turcicum
1995
A peptide secreted by the fungus Exserohilum turcicum, the causal agent of northern leaf blight of corn, was purified. The chemical structure of the peptide was analyzed and two chemical structures are proposed. The peptide is composed of three amino acids in the following sequence: glycine-serine-glutamine. The two proposed chemical structures differ by the degree of hydration of the molecule. One of the proposed peptides was synthesized. Both the synthetic and the natural peptide inhibited chlorophyll synthesis of etiolated corn leaves. The peptide exhibited genotypic specific activity at concentrations of 75 and 100 mg ml-1. At higher concentrations the genetic specific activity was not observed. The synthesized compound inhibited root elongation of corn seedlings. The peptide was detected in infected corn leaves 2 days after inoculation and reached maximal level 4 days after inoculation. The peptide was also detected in a conidial water suspension during conidial germination. The importance of this compound in Northern leaf blight pathogenesis is discussed.
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