Eshel, D., Department of Postharvest Science of Fresh Produce, Institute for Technology and Storage of Agricultural Products, Volcani Center, Bet Dagan 50250, Israel, Department of Plant Pathology and Microbiology, Hebrew University of Jerusalem, Faculty of Agricultural, Food and Environmental Quality Sciences, Rehovot 76100, Israel
Beno-Moualem, D., Department of Postharvest Science of Fresh Produce, Institute for Technology and Storage of Agricultural Products, Volcani Center, Bet Dagan 50250, Israel
Lorang, J.M., Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331-2902, United States
Dinoor, A., Department of Plant Pathology and Microbiology, Hebrew University of Jerusalem, Faculty of Agricultural, Food and Environmental Quality Sciences, Rehovot 76100, Israel
Prusky, D., Department of Postharvest Science of Fresh Produce, Institute for Technology and Storage of Agricultural Products, Volcani Center, Bet Dagan 50250, Israel

Limited black spot symptoms (Quiescent infections) develop on persimmon fruits as Alternaria alternata hyphae penetrate the pericarp of green-immature fruit. Inoculation of persimmon with A. alternata or treatment with a commercial preparation of purified cellulase induced similar black symptoms and higher peroxidase activity in green-immature fruits but not in orange-mature persimmon fruits. Both treatments induced the development of new peroxidase isoforms only in immature fruits - however, no effect was observed on polyphenoloxidase activity. A. alternata was transformed with a construct expressing green fluorescent protein (GFP). Histological analysis of hyphal development using GFP-transformed fungi indicated that symptoms are always found ahead of the leading edge of the hyphae. We suggest that peroxidase increase, induced by the directly penetrating A. alternata, might be involved in the induction of quiescence infection by the pathogen in immature fruits.