Iron-Deficiency–Induced Alterations in Phenolic Composition, Antibacterial and Antifungal Activities of Tunisian Dill (Anethum Graveolens)

Iron (Fe) deficiency strongly influences plant secondary metabolism and bioactivity.Anethum graveolens L. (dill) is rich in phenolic compounds with notable antimicrobial potential, yet the effect of Fe scarcity on these activities remains unclear.In this study, dill plants were grown hydroponically under Fesufficient (+Fe) and Fe-deficient (-Fe) conditions.Fe deficiency significantly enhanced phenolic and flavonoid contents in roots (total phenolics increased by 35% and flavonoids by 20% compared to control), whereas leaves showed minimal changes.Root extracts from Fe-deficient plants exhibited markedly improved antimicrobial activity: antibacterial activity increased against Micrococcus luteus and Staphylococcus warneri (up to 40% larger inhibition zones), and antifungal activity was enhanced against Colletotrichum spp.(up to 45% increase) and Penicillium expansum (30% increase) relative to Fe-sufficient roots.Correlation analyses indicated that phenolic compounds were the main contributors to the enhanced bioactivities.These results demonstrate that Fe deficiency triggers root-specific metabolic reprogramming, boosting phenolic-mediated antimicrobial defenses.This study highlights the potential of cultivating dill under Fe-limited conditions to enhance its antimicrobial properties, with implications for medicinal plant production and bioactive metabolite optimization.t