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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.

Additional keywords: uredospore germination, coffee rust, cinnamic acid derivatives.