Metabolomics using GNPS and in-house analysis platforms reveals unique metabolic traits of endophytic and phytopathogenic Colletotrichum fungi

Phytopathogenic Colletotrichum fungi is considered one of the most important group of phytopathogenic fungi based on economic losses in crops. Phytopathogenic Colletotrichum spp. promote diseases in a wide variety of plants. Secondary metabolites produced by Colletotrichum spp. are likely related to their virulence and mechanism of infection. However, it is not yet well established if secondary metabolites produced by Colletotrichum fungi are responsible for their phytopathogenicity. In order to investigate metabolic differences between endophytic and phytopathogenic Colletotrichum spp., culture media produced by twenty-five isolates of Colletotrichum spp. were investigated, 16 of which were endophytic and 9 were phytopathogenic. Culture media were cleaned-up and analyzed by UPLC-IMS-QToF-HRMS. Raw data were processed using a customized workflow. Results were evaluated using GNPS Molecular Networking and MS2Analyte in-house platform. The combined platforms analyses evidenced that endophytic and phytopathogenic strains have a significant different metabolism. Endophytic strains produce compounds that are common to several strains of the group; on the other hand, phytopathogenic strains produce compounds that are more specific to each isolate. Dereplication of the GNPS exported results using an in-house library of compounds isolated from Colletotrichum fungi combined with in-silico fragmentation tools allowed the identification of 5 compounds in the samples related to phytopathogenic strains, among which 4 display phytotoxic activity. These results suggest that the phytopathogenicity of Colletotrichum strains may be associated with the production of phytotoxic compounds.