افزایش سازوکارهای دفاعی خیار در برابر سفیدک پودری خیار با اسانس بذر کرفس و نانوذرات حاوی اسانس

Due to growing global concern about the extensive use of chemical fungicides and their residual effects on crops, modern plant protection is increasingly relying on non-chemical methods, such as natural plant compounds, as an alternative against phytopathogens. The aim of the current study was an in vivo evolution of the antifungal activity of celery (Apium graveolens) seed essential oil (CSEO) to control cucumber powdery mildew (Podosphaera fusca), identifying the active components, and analyzing the plant defense biochemical/molecular pathways involved in the plant defense response induced by the CSEO. Due to low water solubility, and susceptibility to oxidation in environmental conditions, we synthesized chitosan nanoparticles loaded with CSEO (CSEO-LCNPs) and evaluated their antifungal activity against cucumber powdery mildew. Celery seed essential oil consisted mainly (more than 42%) of D-limonene and some other compounds, including 3-butyl phthalide (14.4%), β-selinene (11.9%), and mandelic acid (10.9%), and effectively inhibited cucumber powdery mildew in greenhouse tests by about 60% compared to the inoculated untreated plants (with 100% diseases). After synthesizing CSEO in a nano-carrier system, the disease severity decreased even further. In inoculated treated plants with CSEO, the concentration of chlorophyll 875.54%, phenolic compounds 71.12%, flavonoid compounds 40.89%, the activity of β-1,3-glucanase 44.43%, chitinase 40.90%, and phenylalanine ammonia-lyase 65.55% was more than the inoculated untreated control. Also, the gene expression of β-1,3-glucanase, chitinase, and phenylalanine ammonia-lyase was 3.4, 2.4, and 2.7-fold higher than the inoculated untreated control, respectively. Furthermore, results showed that CSEO-LCNPs elicited cucumber leaves defense response, including enhancing the accumulation of antioxidant compounds, chlorophyll concentration, enzyme activities, and inducing gene expression, that resulted in systemic resistance in the plants against P. fusca attacks and can be used as a safe and environmentally friendly treatment for managing this disease.