Effects of Different Concentrations of FeEDDHA on Callus Induction and Plant Conversion in Gynura aurantiaca

Gynura aurantiaca, commonly known as purple passion vine (also called purple velvet plant) is an ornamental species belonging to the Asteraceae family, recognized for its striking purplish foliage. While primarily cultivated as an indoor ornamental plant, its reported antioxidant potential, often linked in the literature to anthocyanin compounds, has increased interest in biotechnological applications. This study evaluated the effects of the alternative iron source FeEDDHA on callus induction and plant conversion from leaf explants under in vitro conditions. The standard iron source FeEDTA (100 µM) served as the control. Murashige and Skoog (1962) medium was supplemented with FeEDDHA at 100, 200, 400, and 800 µM. Parameters assessed included callus formation percentage, callus weight, callus area, organogenesis rate, and plant conversion rate. FeEDDHA at 200 µM yielded the highest callus formation, biomass, and area, whereas the highest plant conversion rate was obtained at 100 µM. In contrast, 800 µM markedly reduced callus formation and plant conversion, with complete inhibition in some replicates. Structures obtained during the callus and organogenesis stages were transferred to hormone-free MS medium, where 74% of explants treated with 100 µM FeEDDHA developed into fully rooted plantlets. Overall, precise iron dose optimization is critical: FeEDDHA outperformed FeEDTA at appropriate concentrations, with 200 µM optimal for callus formation/biomass and 100 µM optimal for plant conversion. These findings highlight the importance of iron source selection in micropropagation protocols.