Physiological, anatomical, and transcriptomic analyses reveal the effects of acid rain stress on Akebia trifoliata and the mitigation potential of exogenous curcumin

Acid rain is a global ecological issue severely threatening crop growth. CUR, a natural antioxidant, can enhance the tolerance of plants to abiotic stresses via physiological and molecular modes. As both medicine and food, Akebia trifoliata exhibits high economic value. The effects of acid rain stress on A. trifoliata and the mitigation potential of exogenous CUR remain unclear. To explore the impact of acid rain stress on A. trifoliata and the mitigation potential of exogenous CUR, we investigated the plant growth, physiological characteristics of leaves, anatomical structure, and gene expression of A. trifoliata under acid rain stress before and after treatment with exogenous CUR. The results indicated that under acid rain stress, the contents of chlorophyll a, chlorophyll b, total chlorophyll, and starch and thicknesses of upper and lower epidermis of leaves decreased by 58.16%, 77.88%, 64.77%, 63.85%, 58.93%, and 35.57%, respectively.