Hormetic elicitation of phthalides in celery seeds (Apium graveolens L. var dulce) and its effect on seedling development

Controlled elicitation induces metabolite biosynthesis and enhances crop productivity by activating plant defense in a dose-dependent manner. However, elicitation studies often overlook the concept of hormesis. Here, we describe the response of celery seeds, a valuable source of bioactive phthalides, to elicitation from the hormesis approach. We evaluated 0.1, 1, and 10 mM salicylic acid and 15, 150, and 1500 µg mL−1 chitosan. A gas chromatography-mass spectrometry (GC/MS) analysis revealed that Senkyunolide A is the major compound in celery seed CH2Cl2 extract. At the highest dose (10 mM), salicylic acid increased 2-fold Senkyunolide A content (15.2 ± 1.1 mg g−1) but also affected germination and seedling growth compared to the control. Chitosan induced a hormetic dose-response of antioxidant defense and seedling development variables, increasing 1.5-fold Senkyunolide A content (11.1 ± 1.5 mg g−1) and improving germination time at 15 µg mL−1 compared to the control. These findings show that both elicitors effectively increase the concentration of industrially relevant metabolites in celery seed.