Culture Filtrates of Trichoderma Isolate H921 Inhibit Magnaporthe oryzae Spore Germination and Blast Lesion Formation in Rice

Spore germination and appressorium formation of Magnaporthe oryzae spores was completely suppressed by an ethyl acetate extract of the culture filtrate from the H921 isolate (H921-EAE-CF). Production of antifungal substance(s) in the H921-EAE-CF began to increase up to 3 days after isolate H921 incubation. Furthermore, heat treatment (105 ̊C or 121 ̊C) of H921-EAE-CF did not alter its inhibitory effect on M. oryzae spore germination compared to non-heat-treated H921-EAE-CF. Blast lesion formation inhibition by H921-EAE-CF was dose-dependent. Internal transcribed spacer (ITS) region sequence analysis indicated that this isolate shared similarities with species of the genera Trichoderma. This study suggests that H921-EAE-CF contains some antifungal substances that could be promising candidates for control of rice blast disease.