Identification And Study On The Antifungal Activity Of The Endophytic Fungus Strain H-18 From Carpesium Macrocephalum

One of the mainstreams of sdudy on endophytic fungus is to find active components from traditional medicinal plants and special environmental plants. Strain H-18 was isolated from C. macrocephalum by Research & Development center of Biorational Pesticides, which exhibited obvious antifungal activity in previous research and is worth to study further. The thesis identified strain H-18 by morphologic observations and molecular biology, studied the antifungal activity of the metabolite, isolated and identified the active components of H-18.The main results are as follows:1 The strain H-18 was identified by the morphology method. The characteristics of strain H-18 in CSA culture medium was: colony uplift,the aerial hypha developed, hypha surface showing the garnet with the yellow brown; When observing the hypha branch under microscope,there were two kinds of acervulus: big spore and small spore. The big spore lived in the conidiophore peak with sickle shape and 3-5 septum transversums; many of small sporewere singlecell and egg shape. Therefore, we conclude that strain H-18 belongsto Fusarium.2 To receive PCR products of strain H-18 by using primer ITS1 and ITS4, the ITS-5.8S rDNA sequence was 563 bp. The homology of strain H-18 to F. concolor was up to 99.6%. Based on the phylogenetic tree constructed and the genetic distances, we conclude that strain H-18 belongsto Fusarium concolor.3 The antifungal activity of the acetone extract of endophytic fungus strain H-18 from C. macrocephalum was studied. Results of experiments in vitro showed that the inhibition rates of the acetone extract of strain H-18 on Exserohilum turcicum, Botrytis cinerea and Phytophthora capsici were all higher than 80% at 0.5mg/mL. Thedetached tissue and potted experiments showed that the protective and therapeutic efficacy of the acetone extract of strain H-18 were all higher than 50% at 2mg/mL to Botrytis cinerea and Phytophthora capsici. Therefore, we can conclude that acetone extract of strain H-18 has fine antifungal activity.4. The active components of the acetone extract of strain H-18 were isolated by activity tracking methods. Two compounds were obtained from the acetone extract of strain H-18 by normal pressure column chromatography and TLC. R1 wasβ-sitosterol, and R2 may be ester compound. The inhibition effect of strain H-18 on spores germination of B. Cinerea was studied. R1 showed no obcious effect and the EC50 of R2 was 4.077mg/L.