Physiological mechanism of resistance to anthracnose of different Camellia varieties
Tea oil camellia (Camellia oleifera) is an important oil-producing plant which is widely distributed in the Dabie Mountain of Anhui province in China. Anthracnose (Colletotrichum gloeosporioides) is a common and serious disease which often cause flower and fruit drop in tea oil, leading to 50% or more loss in yields. Different Camellia varieties vary in their resistance to anthracnose. There are few studies on the physiological mechanisms of resistance to anthracnose. In this paper, eight different varieties of Camellia in China were selected for measurement of the content of four polyphenols, flavonoids, phenylalanine ammonia lyase and polyphenol oxidase. Among the polyphenols, catechol and salicylic acid content were related to anthracnose resistance, with the content of the resistant varieties been nearly five to ten times higher than that of the more susceptible varieties. Flavonoid content was also significantly higher in resistant varieties than in susceptible varieties. Activities of the defense-related enzymes phenylalanine ammonia lyase and polyphenol oxidase did not differ between different cultivars. However, enzyme activity of resistant cultivars improved markedly after pathogen inoculation, while those of susceptible cultivars did not change. This study broadens the understanding of the mechanisms of disease resistance in Camellia.
Keywords: Anthracnose, Camellia oleifera, phenylalanine ammonia lyase, polyphenol oxidase.