THE INCIDENCE OF BOTRYTIS CINEREA AND EXPRESSION OF PUTATIVE HOST DEFENCES IN GREEN- AND GOLDEN-FLESHED KIWFRUIT OF DIFFERING HARVEST MATURITY

摘要

This study was carried out on green-fleshed Actinidia deliciosa cv. Hayward, the world's main commercial kiwifruit cultivar, and the recently introduced golden-fleshed Actinidia chinensiscv. Hortl6A. The incidence of Botrytis rots was 2-fold higher inHayward than in Hortl6A, irrespective of fruit harvest maturity. Expression of chitinase activity and antifungal phenolics, in particular a compound with a R_f value of 0.56, was also higher in Hortl6A than in Hayward pericarp tissue. These results suggest that genotype resistance to B. cinerea is greater in Hortl6A than in Hayward fruit, and is associated with chitinases and phenolics. An increase in disease resistance with advanced fruit harvest maturity was more evident in Hortl6A than Hayward, butdid not correlate with Hortl6A hydrolytic enzyme or phenolic activities, suggesting the involvement of other unidentified defence component(s). Delaying fruit harvest can be used to further augment resistance of the Hortl6A cultivar to B. cinerea, but the mode of action remains to be determined.