VIEW ARTICLE

Postharvest Pathology and Mycotoxins

Possible Involvement of an Antifungal Diene in the Latency of Colletotrichum gloeosporioides on Unripe Avocado Fruits. D. Prusky, Department of Plant Pathology, University of California, Riverside 92521, Permanent address: Department of Storage of Agricultural Products, A.R.O. Volcani Center, Bet Dagan, P.O. Box 6, 50-200 Israel; N. T. Keen(2), J. J. Sims(3), and S. L. Midland(4). (2)(3)(4)Department of Plant Pathology, University of California, Riverside 92521. Phytopathology 72:1578-1582. Accepted for publication 10 June 1982. Copyright 1982 The American Phytopathological Society. DOI: 10.1094/Phyto-72-1578.

A preformed antifungal compound was isolated from peels of unripe avocado fruits and identified as 1-acetoxy-2-hydroxy-4-oxo-heneicosa-12, 15-diene. The compound inhibited in vitro vegetative growth of Colletotrichum gloeosporioides and totally inhibited spore germination at 790 μg·ml^–1. Concentrations of the diene in peels of unripe fruits were as high as 1,200 μg·g^–1 fresh weight of peel (~1,600 μg·ml^–1), but these decreased during ripening to about 120 μg·g^–1 fresh weight of peel (~160 μg·ml^–1). Concentrations of the compound decreased differentially during the ripening of two cultivars of avocado fruits that differed in rates of development of symptoms caused by C. gloeosporioides. The evidence supports the hypothesis that the antifungal compound is the basis for latent infections of C. gloeosporioides in unripe avocado peel and that subsequent active infections result from its metabolism during ripening.