VIEW ARTICLE

Physiology and Biochemistry

Isolation, Purification, and Biological Activity of a Self-Inhibitor from Conidia of Colletotrichum gloeosporioides. A. R. Lax, Former research assistant, Department of Plant Pathology, University of Arkansas, Fayetteville 72701, Present address of senior author: USDA, Southern Regional Research Center, New Orleans, LA 70179; G. E. Templeton(2), and W. L. Meyer(3). (2)(3)Professor, Department of Plant Pathology, and professor, Department of Chemistry, respectively, University of Arkansas, Fayetteville 72701. Phytopathology 75:386-390. Accepted for publication 21 November 1984. Copyright 1985 The American Phytopathological Society. DOI: 10.1094/Phyto-75-386.

Low concentrations of conidia (10⁴/ml) of Colletotrichum gloeosporioides f. sp. jussiaea germinated readily, but high concentrations of conidia (10⁷/ml) in water or on water agar germinated poorly. Aqueous extracts from high concentrations of conidia inhibited germination of dilute concentrations of conidia. An inhibitor was extracted from these extracts with chloroform. Thin-layer chromatography of the chloroform extracts gave a single spot of inhibition in assays on the chromatograms. Chloroform extracts were taken to dryness, and the inhibitor was crystallized from hexane as fine colorless needles, m. p. 108- 110 C. Germination of conidia was reduced by approximately 50% at 2 μg of inhibitor per milliliter. Dilutions of the purified inhibitor or conidial exudates gave germination percentages that paralleled those of dilutions of conidia. Chemical analysis revealed a molecular formula of C₁₈H₃₀O₅ and a molecular structure quite different from other known germination self-inhibitors.