Isolation On Endophytic Fungus From Camptotheca Acuminata Decne And Inhibition Activitie To Plant Pathogens

The plant endophyte can metabolize many interesting secondary metabolites with novel structure and distinctive activities,which is an important source of new molecular skeleton and drugs,and has good prospects in the agricultural and medical application. The fermentation product of the strain G-4 isolated from the root of Camptotheca Acuminata Decne has strong antifungal activity on various plant pathogens.Biological characteristics and fermentation liquid of strain G-4 was studied.The main results are as follows:1.Used tissue isolation method on potato dextrose agar,28 strains of endophytic fungi were isolated from the stems, leaves, fruits and roots of Camptotheca acuminata Decne. The results of plat-confront indicated that 28 strains of endophytic fungi had some inhibition on the six plant pathogens: Phomopsis vexans(Sacc.et Syd)Harter,Fusarium oxysporum f. sp. lycopersici,Valsa mali miyabe et Yamada,Gloelsporium fructigenum Blerk,Venturia pirina,Botrytis cinerea.the strain G-4 has a significant antifungal activity on pathogens, the inhibition rates were all more than 60% to the six plant pathogens,and the most rate was 89.68% to the Valsa mali miyabe et.2.Biological characteristics of strain G-4 was studied, the result showed that malt powder was the best medium for its growth; the strain G-4 grew well when the temperature was 28℃and the pH was the range 6.4 from 8; The major carbon sources was fructose,the stain G-4 can grow with no carbon.3.Used hypha growth rate method,the antifungal activity of fermentation liquid by high temperature and filtration treatment showed that the effect was remarkable to the six plant pathogens. The inhibition rate of high temperature treatment was the most 95.04% to Valsa mali at 72h,and the filtration treatment was 94.44%.4.The antifungal activity of the fermentation liquid on the third,fourth,fifth,sixth and seventh day to Phomopsis vexans and Valsa mali was sdudied.The result indicate that the inhibition rate increased with the time of ferment. The EC50 of the strain G-4 fermentation liquid against the mycelia growth of Valsa mali and Phomopsis vexans was 236.43mg/L and 169.06mg/L when the mycelia growed 48h.Otherwise,the different storage time can not influence the antifungal activity of fermentation liquid in the condition of 4℃.5.The inhibition of the strain G-4 fermentation filtrate against spore germination of Valsa mali was investigated.The results indicated that at 4h,8h,12h and 24h after treatiing,the inhibition rate of the spore germination was 38.00%,43.97%,56.06% and 46.93%,respectively,with the inhibition rate at 12h after treating was the highest.In addition,by the in vivo experiment of protectiveaction and therapeutic action against canker of apple fruit.we can say that the effect was obviously with the different concentration of the fermentation filtrate.The protective efficacy was 61.9% and the therapeutic efficacy was 81.6% against canker of apple fruit at the concentration of 480mg/L.