Silicon modulates drought stress and enhances tolerance by improving physiology and key gene regulations in jasmine (Jasminum sambac L.)

Introduction Drought stress is a major abiotic constraint affecting plant growth, physiological processes, and yield. Increasing temperatures and altered precipitation patterns associated with global climate change may increase the frequency and severity of drought, reducing water availability for plant growth. Drought stress can impair photosynthesis and disrupt metabolic functions, consequently affecting flowering and yield, particularly in ornamental crops. Jasminum sambac is an economically important ornamental plant widely cultivated in India for its fragrant flowers and essential oil, with applications in the cosmetic and pharmaceutical industries. However, drought stress can adversely affect its flowering performance and productivity. This study evaluated the effects of sodium metasilicate supplementation on drought-stressed J. sambac . Methods Four treatments were evaluated: control, drought, drought plus 5 mM sodium metasilicate (D+Si), and 5 mM sodium metasilicate alone (Si). Sodium metasilicate was applied once as a soil drench before drought imposition. Physiological parameters, antioxidant enzyme activities, fresh flower weight, thylakoid membrane protein-complex profiles, and the relative expression of putative drought-responsive and silicon-transporter genes were assessed. Results Several physiological parameters differed significantly between D+Si and drought-stressed plants. Sodium metasilicate supplementation significantly modulated the activities of the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX) under drought conditions. Fresh flower weight was significantly higher in D+Si plants than in drought-stressed plants. These responses were also associated with changes in thylakoid membrane protein-complex profiles and the relative expression of putative drought-responsive and silicon-transporter genes. Discussion Sodium metasilicate supplementation was associated with improved physiological and biochemical responses and increased flower yield under drought conditions in J. sambac . These findings suggest that sodium metasilicate may help mitigate the adverse effects of drought stress and support flower production in this ornamental crop.