Study On Antifungal Effects Of Secondary Metabolites Of Chenopodium Ambrosioides L. From Sichuan On Plant-pathogenic Fungi

Chenopodium ambrosioides L., native to America, is one of annual or perennial herbage plant. It grows in most of the China and has become a major invasive plant. It is very useful for controlling it grow and exploitation to study on the antifungal activity and antifungal mechanism.The antifungal activity and antifungal mechanism of secondary metabolites including essential oil, flavonoid and alkalids of C.ambrosioides grown in Sichuan were evaluated at different concentrations and different treatment time with five plant-pathogenic fungi. In the fumigating assay, growth of all fungi was facilitated at 1μL dose essential oil except for Gibberelle zeae (Schw.) Petch and was inhibited when the essential oil dose was beyond 1μL dose. In the poison assay, the IC50 of Rhizoctonia solani Kuha, Curvularia lunata (walk) Boed, Pyricularia oryzae Cav., G. zeae and Pestalotia funerea were 0.734μL·mL^-1, 0.342μL·mL^-1, 0.435μL·mL^-1, 0.370μL·mL^-1 and 0.332μL·mL^-1. In the poison assay of flavonoid, growth of R.solani was inhibited and growth of C.lunata was facilitated. At different concentrations and different treatment times, growth of P.oryzea, G.zeae and P.funerea was inhibited or facilitated. In the poison assay of alkalids, growth of R.solani and P.oryzae was inhibited. At different concentrations and different treatment times, growth of C.lunata, G.zeae and P.funerea was inhibited or facilitated.Fungi was treated with essential oil, flavonoid and alkalids at concentration IC50, 10 mg·mL^-1, 5 mg·mL^-1 separately, then the changes of morphology, protein and DNA were studied by microscopy, SDS-PAGE electrophoresis and agar gel electrophoresis separately. Fungi treated with secondary metabolites of C.ambrosioides at different treat times got some changes more or less, including swarm of protoplast and damage of cellularity, but the DNA had not changes. Protein of P.oryzae treated with flavonoid and alkalids had not changes, but the others of the kind of protein got decrease or increase at different concentrations and different treatment times. These facts some kinds of proteins completely disappeared after treatment was indicated fungi got some damnifies and it cannot return to a former condition. These facts some kinds of proteins disappeared at treatment prophase then appeared as the treatment draw-out or increase was indicated fungi got some damnifies and it can retum to a former condition.