The Inhibitive Activity Of Pyrimorph Against Phytophthora Capasici And Its Mechanism

Pyrimorph is a novel acryl amide fungicide developed by China Agicultural University , Plant Protection Institute of CAAS and Jiangsu Cultivation Chemical Co. LTD. The effects include mycelial growth, sporangium formation, and sporangium germination.were studied in this paper. The effects of pyrimorph on Phytophthora capsici Leonian indoors pot experiment and outdoors field experiment were also investigated , and the research of Pyrimorph on mechanism of action of Phtophthore capsici were discussed. Research results are as follows:The results showed that pyrimorph possessed strong inhibition on mycelial growth, sporangium production with the EC50 values of 2.92,3.07μg/mL, respectively, however,the inhibiting activity on sporangium germination was feeblish,the EC50 value was 20.19.μg/mL.By light microscopy, scanning electron microscopy (SEM) and TEM, the investigations showed that pyrimorph could cause a series of morphological and structural alterations of Phytophthora capsici Leonian hyphae , These changes included excessive branching, the interval between branches shortened, protuberance on the surface of hyphae. The investigations made by transmission electron microscope showed that the most obvious ultrastructure changes of Phytophthora capsici Leonian treated with pyrimorph were cell wall becomes thick, the plasmlemma shrinking,malformed nuclei and damage of vacuole and cells inter structure , and the damage is proporitional the concentration of pyrimorph in substrate.ATP is the existence of bio-energy formation, different concentrations of ATP can promote the growth of mycelium; it can be antagonistic against pyrimorph, and proves that pyrimorph affected the production of ATP.Pyrimorph can chage membrane permeability of Phytophthora capsici, the reason which changed membrane permeabilithy was deduced that pyrimorph damaged the membrane permeability of Phytophthora capsici ultra-structure, caused the loss of cell components. The reason might also be considered as this specific ion-transprort carrier, the particular reason would be further studied.The effect of pyrimorph on dissoluble protein of phytophthora capsici indicated that with the increasing of concentration of doses, the inhibition promoted increasingly .But the specific inhibiting protein synthesis mechanism remains to further study.Mycelial respiration was affected. Pyrimorph exhibited certain inhibition on metabolic approaches of Embden-Meyerhof-Parnas (EMP), tricarboxylic acid cycle (TCA), and hexosemonophosphate (HMP) by measuing the oxygen consumption of pyrimorph combining with three representative inhibitors to the metabolic approaches.The results indicated that pyrimorph could inhibit the approach of HMP significantly.The results of indoors pot experiment and outdoors experiment indicated that the control effects of pyrimorph on Phytophthora capsici Leonian is good.