Biological activity of Kuma bamboo grass (Sasa veitchii) extract against the fungal causal agent (Pyricularia oryzae) of blast disease

Abstract

The secondary metabolites of plants may contain natural compounds as fungicide sources. The antimicrobial activity of the plant Kuma bamboo grass ( Sasa veitchii ) has been known for a long time in Japan. However, its inhibitory activity against plant pathogenic fungi has not been elucidated. In this study, we investigated the inhibitory activity of Kuma bamboo grass extract against Pyricularia oryzae that causes rice blast disease. Kuma bamboo grass extracts obtained through high-pressure reaction/decomposition vessel extraction at 100 °C for 1, 2, 3, and 5 h or 200 °C for 1 h did not inhibit the conidial germination of P. oryzae . Conversely, the extract processed at 200 °C for 2 or 3 h inhibited this process. Compounds with a molecular mass < 1000 Da in the extract exhibited an inhibitory effect against P. oryzae . Furthermore, fungicidal activity was observed by the extracts processed at 200 °C for 2 or 3 h. Internal disintegration of conidia treated with the extract was confirmed by light microscopy, but no disintegration was observed on conidial surface by electron microscopy. In experiments with plants, blast lesion formation was significantly suppressed by the same Kuma bamboo grass extracts. Therefore, the inhibitory compounds of Kuma bamboo grass extract may be useful for developing control strategies against plant diseases such as blast disease caused by P. oryzae. • Sasa veitchii had a fungicidal effect on Pyricularia oryzae. • Many compounds of S. veitchii caused the inhibitory activity against P. oryzae. • S. veitchii extract suppressed blast lesion formation. • Compounds in S. veitchii extract could be used to control fungal diseases.