VARIATION IN PHYSIOLOGICAL AND CHEMICAL CHARACTERISTICS AT DEVELOPMENTAL STAGE IN DIFFERENT DISEASE-RESISTANT VARIETIES OF CAMELLIA OLEIFERA

Abstract

Camellia oleifera Abel. is an important edible oil tree species from Southern China. Anthracnose, caused by Colletotrichum gloeosporioides (Penz.), is responsible for more than 50% of C. oleifera production loss, and C. oleifera varieties differ in their resistance to anthracnose. The aim of this study was to assess resistance mechanisms by monitoring physiological and biochemical parameters of differentially resistant cultivars during the development of C. oleifera. C. oleifera fruit coats were analyzed between May and September for tannins, anthocyanins, soluble sugar content, pH, buffer capacity, activity of three enzyme s(Phenylalanine ammonia lyase; polyphenol oxidase; peroxidase) and free radical scavenging capacity. Anthocyanins, soluble contents and free radical scavenging capacity were related to anthracnose resistance, with anthocyanins and soluble sugar contents of the resistant varieties nearly twofold higher than those of susceptible varieties. The results of free radical scavenging capacity showed that extracts from highly resistant varieties of C. oleifera fruit coats performed more efficiently in the scavenging of free radicals than those from susceptible varieties. The three enzyme activities of highly resistant varieties rose rapidly and continuously, while those of medium resistant and highly susceptible varieties increased initially and then decreased. Tannins, pH and buffer capacity showed no significant differences between different cultivars. This study broadens the understanding of disease resistance mechanisms in C. oleifera.