Isolation And Bioactivity Analysis Of Secondary Metabolites From Trichoderma Asperellum CBS 433.97

Trichoderma spp.is a kind of widely used biocontrol fungi.Secondary metabolites of Trichoderma play an important role in its biocontrol mechanism.At present,compounds form Trichoderma asperellum CBS 433.97 were isolated and the roles inhibiting growth of plant pathogenic fungi,regulating plant growth and inducing plant disease resistance were analyzed.The main contents are as follows:1.Isolation and identification of secondary metabolites of Trichoderma asperellum CBS433.97.The silica gel column chromatography and High performance liquid chromatography(HPLC)were used to separate and purify the fermentation products of Trichoderma asperellum CBS 433.97.The structure of compound was identified by nuclear magnetic resonance(NMR)and high resolution mass spectrometry(HR-ESI-MS).At present,nine compounds have been isolated from CBS 433.97,which are 5-hydroxyhexan-4-olide(1),trans-2-anhydromevalonic acid(2),pestalotiopin A(3),harziandione(4),phenylethanol(5),p-methoxyphenylethanol(6),ergosterol(7),adenosine(8)and adenine(9),respectively.2.Analysis of antifungal activity of compounds.The results showed that compound 5,6and 9 had inhibitory effect on the mycelial growth of Fusarium graminearum and Fusarium oxysporum f.sp.Momordicae.Meanwhile,compounds 5 and 6 decreased activities of cell wall degrading enzymes,as well as superoxide dismutase(SOD)and catalase(CAT)of pathogen mycelia suggesting inhibited pathogenic ability and antioxidant capacity of the two pathogens.3.Analysis of growth-promotion and disease resistance induced by compounds.Wheat and bitter melon seeds were treated with different concentrations of compound using seed soaking method.The plant height,root number,root length and leaf size were determined.The results showed that compound 2,3,5,7,8 had significant growth-promoting effects on wheat and bitter melon plants.Under pathogen stress,PPO and POD activities,as well as free proline and malondialdehyde contents in wheat and bitter melon leaves were determined after compound treatment.The results showed that compound 2-6 increased the activities of PPO and POD,as well as the content of free proline,while decreased the content of MDA in wheat and bitter melon leaves.The results showed that compound 2-6 induced disease resistance of wheat and bitter melon plants.In addition,compound 2,4,5,6,7 improved disease resistance of wheat by up-regulating expression of disease-related protein synthesis genes LTP-1,PR1.1,PR4,Chi1,and Glu1 as well as proline synthase gene P5 CS in wheat leaves.4.Analysis of control efficiency of plant diseases.Compounds 5,6,8 and 9 were used to control wheat scab in greenhouse and field with the concentration of 300 mg/L.The control efficiency in greenhouse was 62.28%,4.78%,36.04 and 55.14 %,respectively.And the control efficiency in field was 36.53 %,17.47 %,46.48 % and 25.69 %,respectively.In addition,compound 5 and 8 had better control effect(36.53 % and 46.48 %)on wheat scab when the concentration was 300 mg/L than 250 mg/L hymexazol suggesting they had potential application in the development of biological pesticides.