Synergistie Action Of Tea Saponion To Two Fungicides Against P. Theae And Its Mechanism

The antifungal activities of Tea saponion (TS)、mancozeb (MA)、carbendazim (CA) and their combinations against P.theae were analyzed by mycelial growth rate method and spore germination method. The results showed that TS didn’t only display an antifungal activity against mycelial growth and spore germination, but also enhanced significantly the antifungal activities of MA and CA against P.theae. The co-toxicity coefficients (CTC) of the combination of TS and MA at 3:7 against mycelial growth and spore germination were respectively 136.96 and 309.77 and those of the combination of TS and CA at 6:4 were respectively 396.20 and 173.91, which suggested that their combination displayed a synergistic antifungal interaction against P.theae.The antifungal mechanisms of the combinations of TS and MA or CA were studied. The results showed that after P.theae mycelia were treated with TS, MA and their combination, a significant increase of the relative permeability of plasma membrane, Alkaline phosphatase(AKP) leakage and the activities of protease and chitinase was observed, and the concent of protein and reducing sugar of P.theae mycelia was change. Moreover, TS could enhance the change when TS was combined with MA at 3:7. A similar change was observed when TS was combined with CA at 6:4. These stated that TS exhibited the antifungal activity and synergism through inducing the activities of protease and chitinase, destroying mycelial cell structure and causing the leakage of intracellular constituents.