Abstract:

The aims are to explore the inhibitory effect and mechanism of Coptis chinensis, Glycyrrhiza uralensis and Cinnamomum cassia extracts on Pyricularia grisea, and lay a theoretical foundation for developing new inhibitors of Pyricularia grisea. The antifungal activity was determined by the hypha growth rate method. The cell membrane permeability of hyphae, material synthesis and metabolism, and ultra microstructure of hyphal cells were observed by the conventional indoor analysis method. The results showed that the three extracts had strong inhibitory activity on the mycelial growth of Pyricularia grisea. The half fungal inhibitor concentration of Coptis chinensis, Glycyrrhiza uralensis and Cinnamomum cassia were 4.17 mg/mL, 4.48 mg/mL and 5.22 mg/mL, respectively. After treated with the three extracts, malondialdehyde content and conductivity leakage of Pyricularia grisea hypha increased, and the contents of pyruvate and soluble protein decreased, and the hyphae showed morphological changes and other abnormal growth. It can be seen that the three extracts have outstanding inhibitory effect on Pyricularia grisea, and they can destroy the cell membrane and ultramicroscopic morphology and interfere with the synthesis and metabolism of substances, which are expected to be developed as inhibitors of Pyricularia grisea.

Key words: rice disease: Pyricularia grisea, antifungal activity, antifungal mechanism, plant extract, Coptis chinensis, Glycyrrhiza uralensis, Cinnamomum cassia