VIEW ARTICLE

Physiology and Biochemistry

Stimulation of Sexual Reproduction in the A2 Mating Type of Phytophthora cinnamomi by Oleic Acid and Lipids from Avocado Roots. A. I. Zaki, Department of Plant Pathology, University of California, Riverside 92521; G. A. Zentmyer(2), J. J. Sims(3), and N. T. Keen(4). (2)(3)(4)Department of Plant Pathology, University of California, Riverside 92521. Phytopathology 73:199-203. Accepted for publication 28 July 1982. Copyright 1983 The American Phytopathological Society. DOI: 10.1094/Phyto-73-199.

Lipids extracted from avocado roots stimulated the formation of oogonia and oospores in four A2 mating type isolates of Phytophthora cinnamomi. Fractionation of the extracts showed that biological activity was associated with fractions that yielded spectral data similar to those of unsaturated fatty acids and their triglycerides. Authentic oleic acid, triolein, and, to a lesser extent, palmitoleic and linoleic acids, also stimulated the formation of oogonia and oospores in these isolates. Neither the natural lipids from avocado roots nor the authentic compounds stimulated sexual reproduction in the A1 mating type. Stimulation of sexual reproduction in the A2 mating type with oleic acid or triolein occurred when the fungal isolates were grown in V-8 broth for 48- 72 hr, washed momentarily in sterilized distilled water, and placed between two sheets of cheesecloth impregnated with 0.5- 10 mg of the test substances. Oogonia and oospores did not form when these conditions were varied.