Application of Osthol Induces a Resistance Response Against Powdery Mildew in Pumpkin Leave

Plants can defend themselves against fungal infection by natural means inducedby biotic and abiotic elicitors. Osthol is a natural compound extracted from dried fruits ofCnidii Monnieri Fructus. In this study, it has been shown to not only be a fungicide withacceptable curative properties (control efficacy of 68.72), but it also showed a significantprophylactic effect (with control efficacy of 77.36) against pumpkin powdery mildew at aconcentration of 100 μg·mL-1. In pumpkin leaves with/or without inoculation ofSphaerotheca fuliginea, osthol treatment induced the accumulation of chitinase andperoxidase and enhanced the transcription of chitinase gene in non-inoculated leaves. Thepotentiation of phenylalanine amonia-lyase activity in leaves by osthol application andfollowing inoculation was absent in that with inoculation or osthol treatment, indicatingthat induced PAL in osthol-pretreated plants was inoculation-mediated. In conclusion, thisnatural compound could induce resistance response in the plant against powdery mildew.