Evidence of Phytoalexins in Rhizome of Atractylodis Maceocephalae Koidz Infected with Sclerotium rolfsii sacc Following Treatment with the Polysaccharides of Chrysanthemum indicum

Atractylenolides compounds (atractylenolide-I, atractylenolide-II and atractylenolide-III) extracted from Atractylenolides macrocephala were analysed for their differential presence in the rhizome of both the infected and healthy plants and its fungitoxicity on prophylactic treatment with polysaccharides of Chrysanthemum indicum against Sclerotium rolfsii. It was evident that the plant under stress by pathogen has instigated the significant synthesis and accumulation of atractylenolide-II and atractylenolide-III in the rhizome of plants as a result of elicitation with polysaccharides of C. indicum. Our results also showed that the absence of atractylenolide-II in the rhizome made the plant susceptible to S. rolfsii. Furthermore, on in vitro antifungal studies, exogenous application of atractylenolide-II with the concentration of 200 μg/ml showed a significant inhibitory effect on mycelial growth by achieving a 77.23% antifungal activity rate, and a minimal inhibitory effect at a concentration of 12.5 μg/ml with atractylenolide-II. To our knowledge, this novel study on phytoalexins in A. macrocephala suggested that A. macrocephala plants produce elevated levels of atractylenolide-II and atractylenolide-III in a pattern typical of phytoalexins, in response to an eliciting treatment after infection.