Study On The Inhibition Of Plant Pathogens By Fungi Of Chaetomium And Related Gener

Chaetomium is one of the larger genera of the fungal subphylum Ascomycotina,in which more than 400 metabolites have been isolated and more than 100 compounds have been reported for the first time or are new to Chaetomium.In order to find active fungi from the genus Chaetomiaceae that are resistant to plant diseases and the active substances in them,In this study,five strains of fungi of the genus Chaetomium and similar genera were used as test material in an attempt to identify unexploited and biologically active strains.Finally,the compounds that can be produced are isolated and identified,leading to the discovery of monomeric compounds with good activity.The specific findings of the study are as follows:The test fungi were identified by ITS sequencing and fermented in small quantities in six ways.The fungal crude extracts were tested for antioxidant activity,phospholysis activity and antibacterial activity,and the active strain SD-280 was selected.Strain SD-280 is C.cochliodes,its fungal crude extracts inhibit Fusarium fujikuroi,Rhizoctonia solani,Ralstonia solanacearum,Pseudomonas syringae,Xanthomonas oryzae and Xanthomonas campestrus.Rice crude extracts with good activity and abundant metabolites were selected for bulk fermentation,and the compounds isolated were white powder.The compound was confirmed as chetomin by ¹H-NMR and ESI-MS and chromatographic comparison of the standards.A review of the literature revealed that chetomin has good biological activity in clinical practice,first reported as an anti-tumour as a chemotherapeutic agent for cancer,but resistance to plant pathogens in agriculture has rarely been reported.In this study,the antimicrobial activity of chetommin was tested using the mycelial growth rate inhibition method and the 96-well plate method.The antifungal activity of chetomin was reported for the first time against Fusarium fujikuroi and Rhizoctonia solani.It showed strong antibacterial activities against Xanthomonas oryzae with MIC value of 3.91μɡ·m L^-1.The MIC values of 125μɡ·m L^-1,125μɡ·m L^-1and 62.5μɡ·m L^-1 were obtained for Ralstonia solanacearum,Pseudomonas syringae and Xanthomonas campestrus,respectively.In this study,five strains of Chaetomium and their morphologically similar fungi were screened for the active strain,Chaetomium cochliodes SD-280.The antibacterial activity of the isolated compound chetomin was tested to provide a theoretical basis for the further exploitation of the fungal resources of Chaetomium and to provide alternative strains and lead compounds for the development of new fungal-derived pesticides.