Metabolic Profiling of Endophytic Fungi Acting as Antagonists of the Banana Pathogen Colletotrichum musae
Christian Joseph Cumagun1, Katja Lenz2, Ruth Jakobs3, Caroline Müller3, Anna Rathgeb2, Petr Karlovsky2
1University of the Philippines Los Banos, Crop Protection Cluster, Philippines
Three endophytic strains Phomopsis sp., Fusarium proliferatum, and Tinctoporellus epimiltinus isolated from various plants in the rainforest of the Philippines were investigated regarding their ability to repress growth of the pathogenic fungus Colletotrichum musae on banana. In vitro plate-to-plate assay and an in vivo sealed box assay were conducted. Volatile profiles as well as the composition of the secreted metabolome were studied in commercial versus natural potato dextrose medium. All tested endophytes were able to statistically significantly reduce C. musae growth compared to the control (p ≤ 0.05). The type of medium could not be shown to have a statistically significant effect on lesion size of C. musae on banana (p = 0.05). No interaction between fungal strain and medium could be shown. On the commercial medium, no differences between the performance of the fungi and control treatments could be found (p = 0.1405), while there were statistically significant differences between the fungal strains on natural medium (p = 0.04026). Lesions on banana that were incubated with Phomopsis sp. on natural medium were statistically significantly but only slightly bigger than those incubated with F. proliferatum (p = 0.0139). The volatile profiles of these two strains and one pathogenic strain F. graminearum were assessed using polydimethylsiloxane tubes and analysed via gas chromatography mass spectrometry. Twelve different volatiles could be detected. To reveal if growth on the commercial PDA causes differences in the metabolism of the fungi in contrast to growth on natural PDA, metabolic footprints were assessed via high performance liquid chromatography. After excluding all signals from the media, a total of 388 fungi-associated mass to charge ratio features with chromatographic peak areas higher than 100,000 in the raw data in all replicates of at least one group were detected.
Keywords: Banana anthracnose, Colletotrichum musae, endophytic fungi, secreted metabolites, volatile organic compounds
Contact Address: Christian Joseph Cumagun, University of the Philippines Los Banos, Crop Protection Cluster, College, 4031 Los Banos, Philippines, e-mail: cumagundaad-alumni.de