Iron Chlorin E6 enhances drought resilience in Camellia oleifera Abel

This study investigates the effects of Iron Chlorin E6 (ICE6) on the physiological and biochemical responses of Camellia oleifera plants under both normal and drought stress conditions. Varying concentrations of ICE6 (0 µg/L, 20 µg/L, 40 µg/L and 80 µg/L) were applied to C. oleifera plants to assess physiological parameters, including photosynthetic rate, chlorophyll content (SPAD, Soil Plant Analysis Development chlorophyll meter), antioxidant enzyme activity, proline content (Pro), soluble sugars (SS), soluble proteins (SP), abscisic acid (ABA) levels and gene expression. Under well-watered conditions, 80 µg/L ICE6 significantly enhanced net photosynthetic rate (Pn) and SPAD values by 113.73% and 11.57%, respectively, compared to the control, while promoting indole-3-acetic acid (IAA) and soluble protein accumulation. Under drought stress, ICE6-treated plants exhibited improved stress tolerance, with reduced malondialdehyde (MDA) content by 18.32% (20 µg/L), 14.14% (40 µg/L), and 30.84% (80 µg/L) compared to the control, alongside enhanced antioxidant enzyme activities, ABA signaling, and proline accumulation, mitigating oxidative damage. Among the concentrations tested, 80 µg/L ICE6 delivered the greatest overall benefit by achieving the highest net photosynthetic rate (113.73%) and SPAD value (11.57%) under well-watered conditions, and the lowest MDA accumulation (30.84%) under drought, thus identifying it as the optimal dose in this study. This study provides a theoretical foundation for the use of ICE6 as a multifunctional plant growth regulator in C. oleifera and offers innovative strategies to enhance drought resistance in this economically significant crop.