Desmos chinensis: A new candidate as natural antifungicide to control rice diseases

Nineteen plant extracts from 16 medicinal plants were assayed for their antifungal activity against rice pathogenic fungi on PDA plates containing plant extracts. Among the plants tested, Aegle marmelos, Desmos chinensis, and Micromelum minutum revealed moderate to strong activities against 5 tested fungal species with more than 65.1% inhibition. The dichloromethane extract from D. chinensis leaves showed high antifungal activity against all 6 fungi. The dichloromethane extract possessed antifungal activity against Bipolaris oryzae, Pyricularia oryzae, and Sclerotium rolfsii with minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) values ranging from 3.9 to 31.2 μg/ml and 31.2 to 500 μg/ml, respectively. Bioautography assay on TLC plates with Bipolaris setariae, Curvularia lunata, Fusarium moniliforme, P. oryzae, and S. rolfsii displayed high antifungal activity with Rf value ranging from 0.32 to 0.37. Effects of the extract on the morphology of B. setariae, C. lunata, F. moniliforme, P. oryzae, and S. rolfsii were observed by scanning electron microscopy. The micrographs of mycelia and spores treated with the extract at 4MIC illustrated aberrant surface morphology and reduced conidial formation in 4 fungal species. The results demonstrated that D. chinensis extract possess antifungal activity against phytopathogenic fungi and the activity might lead to irreversible cellular disruption.

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► Nineteen plant extracts of medicinal plants were evaluated for antifungal activity.
► Desmos chinensis leaves extract demonstrate promising antifungal potential.
► The extract was highly effective against Pyricularia oryzae with a MIC value of 3.9 μg/ml.
► Electron micrographs showed distorted mycelium and rough with wrinkle cell surfaces.