VIEW ARTICLE

Resistance

Development of Resistance to Infection by Botrytis cinerea and Penicillium expansum in Wounds of Mature Apple Fruits. S. Lakshminarayana, Visiting professor, Department of Pomology, University of California, Davis 95616, Present address: Departamento de Biotecnología, Universidad Autonoma Metropolitana-Iztapalapa, Mexico, D. F. 09340; N. F. Sommer, V. Polito, and R. J. Fortlage. Postharvest pathologist, Professor of pomology, and Staff research associate, respectively, Department of Pomology, University of California, Davis 95616. Phytopathology 77:1674-1678. Accepted for publication 10 August 1987. Copyright 1987 The American Phytopathological Society. DOI: 10.1094/Phyto-77-1674.

Wounds in harvested, mature, preclimacteric Golden Delicious and Granny Smith apples exhibited healing by formation of wall thickenings. Microscopic examination revealed a barrier of cells with wall thickenings extending four to six cell layers or more from the wound. Histochemical tests of cell walls near healed wounds were positive for phenolic substances, tannins, lignins, and callose after 38 days at 5 C and 14 days at 20 C. Healed wounds were significantly more resistant to conidia of Botrytis cinerea and Penicillium expansum than freshly inflicted wounds. Wounds became resistant within 4 days at 5 C.