The incidence of Botrytis cinerea and expression of putative host defences in green and goldenfleshed kiwifruit of differing harvest maturity

Abstract

This study was carried out on greenfleshed Actinidia deliciosa cv Hayward the worlds main commercial kiwifruit cultivar and the recently introduced goldenfleshed Actinidia chinensis cv Hort16A The incidence of Botrytis rots was 2fold higher in Hayward than in Hort16A irrespective of fruit harvest maturity Expression of chitinase activity and antifungal phenolics in particular a compound with a Rf value of 056 was also higher in Hort16A than in Hayward pericarp tissue These results suggest that genotype resistance to B cinerea is greater in Hort16A 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 Hort16A than Hayward but did not correlate with Hort16A 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 Hort16A cultivar to B cinerea but the mode of action remains to be determined