VIEW ARTICLE

Physiology and Biochemistry

Germination of Coffee Rust Uredospores and Their Inhibition by Cinnamic Acid Derivatives. Mark A. Stahmann, Professor of Biochemistry, College of Agricultural and Life Sciences, University of Wisconsin-Madison, Madison 53706 (M.A.S.); Maria Raphaela Musumeci(2), and Walkyria B. C. Moraes(3). (2)(3)Fellows of Conselho Nacional de Pequisas, Instituto Biológico, São Paulo, 01000, Brazil, S.A. Phytopathology 66:765-769. Accepted for publication 12 November 1975. DOI: 10.1094/Phyto-66-765.

Germination of uredospores of the coffee rust fungus (Hemileia vastatrix) was influenced by the ratio of the spore concentration to the volume of Tween-20 solution on which the spores were floated. Uredospore clumps readily formed a film in which spores floated and spread on the surface. The possible role of this film in the infection process is discussed. Twenty-four cinnamic acid derivatives were assayed for uredospore germination inhibition. The similarity in uredospore germination inhibition and chromatographic properties of the coffee rust germination self-inhibitor and that of some methoxycinnamic acids suggest that the coffee rust self-inhibitor may be a cinnamic acid derivative.