Inhibitory Potential of Metabolites Produced by Cercospora Sp. Strain ME202 Isolated from Trifolium Incarnatum Against Anthracnose Caused by Colletotrichum Orbicular

Chemical fungicides are mainly used to control Colletotrichum orbiculare, but this fungal pathogen usually develops resistance to the pesticides. Natural compounds are therefore desirable for controlling C. orbiculare. Here, a culture filtrate (CF) from ME202, a fungal strain isolated from Trifolium incarnatum in Shimane Prefecture in 2020, was tested in vitro and found to inhibit conidial germination of C. orbiculare. The inhibitory compound in ME202-CF was soluble in ethyl acetate. The ethyl acetate extract of ME202-CF (ME202-ECF) significantly inhibited in vitro conidial germination of C. orbiculare in a dose-dependent manner and lesion formation on cucumber leaves. The inhibitory compounds were heat stable at 40-121 degrees C and molecular mass >= 500 and >= 1000 Da. Thin layer chromatography-bioautography of ME202-ECF showed that the compounds inhibiting C. orbiculare growth had an Rf of 0.81 and 0.91. Furthermore, ME202 was found to be a member of the genus Cercospora through sequence analysis of the internal transcribed spacer and 5.8 S rDNA. These results suggest that secondary metabolites of Cercospora spp., such as ME202, can be used to develop new fungicides against anthracnose.