Impact of drought stress on biochemical and molecular responses in lavender (Lavandula angustifolia Mill.): effects on essential oil composition and antibacterial activity
Ramin Hosseini, Mahsa Heidari
Abstract
(lavender) to different levels of water deficit, with field capacity (FC) treatments set at 20%, 40%, 60%, and 80%. We assessed various biochemical parameters, including protein content, chlorophyll a and b levels, flavonoid and phenolic content, and antioxidant activity, to determine how drought stress affects lavender's primary and secondary metabolism. As water availability decreased, we observed a reduction in total protein and chlorophyll content, while the highest levels of flavonoids, phenolics, and antioxidant activity were recorded in control plants at 80% FC. Gene expression analysis of key terpene synthase genes revealed differential expression patterns, with linalool synthase and α-pinene synthase peaking at 40% FC, and 1,8-cineole synthase and β-phellandrene synthase reaching their highest activity under severe drought (20% FC). Despite this, a clear correlation between gene expression and metabolite accumulation in essential oils was not observed. Drought-induced changes in essential oil composition were associated with enhanced antibacterial activity, particularly against foodborne Gram-positive and Gram-negative bacteria, suggesting that water stress can modulate the therapeutic potential of lavender oil.