Study On Induction Of Phytoalexins In Cotton And Saponins In Platycodon Grandiflorum

In this thesis, kinds of elicitors were applied to cotton leaves and suspensive cultured cells of Platycodon grandiflorum., the effect and mechanism of the induction of plant secondary metabolites by elicitors were explored. The result was elicitor can induce new active composition in the plant tissue and increase the content of the active composition in suspensive cultured plant cells. This result is a reference data for studies on metabolic mechanism and utility of plant secondary metabolites.1, As to cotton leaves, two method were applied: infected by pathogen directly and treated with biotic elicitors. Analysizing the chemical composition of the cotton leaves infected by Verticillium dahliae and treated by artificially synthesized oligosaccharide, many phytoalexins were found induced in both leaves. In tne leaves infected by Verticillium dahliae phytoalexin MW 280 was induced. In the leaves treated by oligosaccharide, five phytoalexins MW 354, 268, 282, 11 land 156 were induced. Therefore, infected by pathogen directly and treated with biotic elicitors both can induce the phytoalexins effectively. The result can be a theoretical foundation. The action of the artificially synthesized oligosaccharide was varified furtherly.2, As to suspensive cultured cells of Platycodon grandiflorum., treated with biotic elicitors from different fungus. Treated suspensive cultured cells of Platycodon grandiflorum. with elicitors prepared from Aspergillus nige, Mucor spinosus and Rhizopus arrhizus in the same consistency, cell fresh weight and total saponins content were increased in varying degrees. The total saponin content can be 1.5 times of the contract in the cells treated by Mucor spinosus on 0 day after inoculated for 16 days. The total saponin content can be 1.6 times of contractin the cells treated by Aspergillus nige on 9 day after inoculated for 20 days. Therefore, increasing the content of the secondary metabolites in suspensive cultured plant cells by treated with fungal elicitors is a effective method.3, This thesis also analysized the effect and influent factors and clarified the inducing mechanism and utility prospect of elicitor. The effect of elicitor was related to many factors such as the type of elicitor, the consistency of elicitor, time of the system treated by elicitor, time of the elicitor applied and the type of the system treated by elicitor. The changes of plant metabolism induced by elicitor induced defensive actions in plant. It is a successive signal transduction process. The mechanism is very difficult, but theoretical and practical studies on it are both important to biology and medical science.