Association of Chitinase and â-1,3-Glucanase Activities with Host Resistance Against Fusarium Wilt In Melon Seedlings

Fusarium wilt (Fw) caused by Fusarium oxysporum f. sp. melonis is an important disease of melon in Heilongjiang Province, China. In this study, we investigated the relationships between host resistance and the activities of two enzymes, chitinases and β-1,3-glucanase, which have been shown to play important roles in host defense response against pathogen attacks. The correlation of activities of the two enzymes upon inoculation of Fw pathogen with host resistance in 14-day old melon seedlings was investigated. Different resistance of melon cultivars to F. oxysprum f. sp. melonis was correlated with the levels of chitinase and β-1, 3-glucanase. The enzyme levels increased on seedling of resistant melon cultivars inoculated with the F. oxysprum f. sp. melonis. The activities of two enzymes in resistant variety increased faster and higher than that in susceptible varieties. 7 days after inoculation, the activities of chitinase and β-1, 3-glucanase in highly resistant variety MR-1 were 3.2 times and 2.9 times of these in highly susceptible variety Qitian No1, respectively. The two enzymes activity levels were correlated positively with melon resistance to F. oxysprum f. sp. melonis, and two enzymes activity expressed specially in tissues. The activities in root were higher than these in leaves. The results showed that chitinase and β-1, 3-glacanase were related to resistance of melon to Fusarium wilt significantly and can be used as biochemical marker for screening resistant melon cultivars to F. oxysprum f. sp. melonis.