Co-Authors:
Prusky, D., Department of Fruit and Vegetable Storage, The Volcani Center, P.O. Box 6, Bet Dagan, 50250, Israel
Kobiler, I., Department of Fruit and Vegetable Storage, The Volcani Center, P.O. Box 6, Bet Dagan, 50250, Israel
Fishman, Y., Department of Fruit and Vegetable Storage, The Volcani Center, P.O. Box 6, Bet Dagan, 50250, Israel
Sims, J.J., Department of Plant Pathology, University of California, Riverside, California, 95251, United States
Midland, S.L., Department of Plant Pathology, University of California, Riverside, California, 95251, United States
Keen, N.T., Department of Plant Pathology, University of California, Riverside, California, 95251, United States
Abstract:
A new antifungal compound was isolated from peel and flesh of unripe avocado fruits and identified as 1‐acetoxy‐2,4‐dihydroxy‐n‐heptadeca‐16‐ene. The maximal concentration of the anti‐fungal monoene in unripe fruits was about 800 μg. g−1 fr.wt. During ripening the monoene decreased to 40 μg. g−1 fr.wt. concomitantly with the appearance of disease symptoms. The concentration of the previously described antifungal diene, 1‐acetoxy‐2‐hydroxy‐4‐oxo‐heneicosa‐12,15‐diene (Pruskyet al. 1982), in avocado peel was 1,600 μg. g−1 fr.wt. in unripe fruits, decreasing during ripening to 120 μg. g−1 fr.wt. At 750 μg. ml−1 the inhibition of germ tube elongation of germinated conidia by the antifungal monoene and the antifungal diene was 15 % and 44 %, respectively. A 1: 1 mixture of both antifungal compounds in concentrations ranging from 50 to 750 μg. ml−1, showed synergistic activity and increased the percent of inhibited germ tubes of germinated conidia up to 15 % over the sum of activities of the separate compounds. The results are discussed in relation to the hypothesis that the antifungal diene and the antifungal monoene are involved in the quiescence of the germinated appressoria of Colletotrichum gloeosporioides in unripe avocado fruits. Copyright © 1991, Wiley Blackwell. All rights reserved