RESPONSES OF CHITINASES IN KIWIFRUIT TO CURING AND TO LONG-TERM STORAGE

Endochitinase activity and total protein content increased in stem plu gs of kiwifruit (Actinidia deliciosa var. deliciosa cv. Hayward (A. Ch ev.) C.F. Liang et A.R. Ferguson) that were free of disease symptoms a nd had been ''cured'' for 7 days at 20 degrees C, immediately followin g harvest. Isoelectric focusing, enzyme-linked immunosorbent assay (EL ISA), and Western blots were used to identify chitinase isoforms induc ed by this treatment. Curing did not induce new chitinase isoforms, bu t appeared to increase expression of an existing approximate to 30 kDa protein, with putative chitinase activity, since it bound to antibodi es against sugar beet chitinase. Chitinase activity also increased sig nificantly in response to prolonged storage (6 weeks at 0 degrees C) a nd inoculation with the pathogen, Botrytis cinerea (Pers.).