Study On Induced Resistance Phenolic Substance And The Mechanism Of Transduction Of Inducing Signal In Cucumber Seedling

In this thesis, kinds of inducers were applied to cucumber seedlings, the effect and mechanism of the induction of plant secondary metabolites by inducers were explored. The result was that inducer could induce new active compositions in the plant. This result was a reference data for studies on metabolic mechanism and utility of plant secondary metabolites. 1. As to cucumber seedlings, stress and SA (Salicylic Acid) were applied to induce its disease resistance. We chose two-leaf-old cucumber seedlings as our experiment material. At first, a certain strengthen local stress and a certain content SA were stimulated on the first real leaves of the cucumber seedlings. After challenging inoculation, resistances were checked. The results were that stress and SA could both induce the resistance of cucumber seedlings to Cladosporium cucumerinum. Analysizing the chemical composition of the cucumber second real leaves, many phytoalexins and lignine were both found induced in leaves. Therefore, the result was the production and accumulation of lignine and the production and accumulation of phytoalexins after being treated of the first real leaves by inducers. The result can be regarded as a theoretical foundation. The action of the mechanical stress was verified furtherly. 2. Resistance signals transduction of inducers in cucumber seedlings. Mechanical stress inducer and chemical SA inducer were used to treat the first real leaves of cucumber seedlings. Before induced, the leaves were treated by RGD(Arg-gly-Asp) and DGR, while the controls were not treated by RGD and DGR. Each treated group was divided into two teams. One was challenging inoculated and another one not. After that, the incidence of disease of each treated group was checked. By assay the changes of the lignine and the phytoalexins, we get a result that after treated by RGD, both indexes are similar to the control while the groups treated by DGR opposite. Therefore, The stress and SA induced resistance is depended on the RGD specific mediated adhesion between cell wall and plasma membrane. There is a similar analysis between mammal cell and the plant cell on the stress signal transduction, which the signaling across a dynamic continuum involving the "ECM-Integrin-cytoskeleton"system. 3. This thesis also analysized the effect and influent factors and clarifyied the inducing mechanism and utility prospect of inducer. The effect of inducers was related to many factors such as the type of inducer, the consistency of inducer, time of the system treated by inducer. The changes of plant metabolism induced by inducer induced defensive actions in plant. It is a successive signal transduction processs. The mechanism is very difficult, but theoretical and practiceal studies on it are both important to biology and medical science.