Initial simulated acid rain impacts reactive oxygen species metabolism and photosynthetic abilities in Cinnamonum camphora undergoing high temperature

Abstract

Cinnamomum camphora has great economic value for extensive applications. It is widely planted in the south of China, and is often exposed to acid rain following high temperature (HT). To study the effects of acid rain on C. camphora undergoing HT, the reactive oxygen species metabolism and photosynthetic abilities in the treatment with initial simulated acid rain (SiAR) and following HT (40 °C) were investigated. After SiAR pretreatment, the levels of O2− and H2O2 and lipid peroxidation in C. camphora increased under HT stress compared with normal temperature (28 °C). High temperature after SiAR pretreatment promoted the inactivation of enzymatic antioxidants, including superoxide dismutase, peroxidase, catalase, ascorbate (AsA) peroxidase, monodehydroascorbate reductase, dehydroascorbate reductase, and glutathione (GSH) reductase, and further decreased the content of non-enzymatic antioxidants, including AsA, GSH and carotenoids. Photosystem II (PSII) efficiency in C. camphora declined under individual SiAR and HT stress, and HT after SiAR stress aggravated the decrease by aggravating the reduction of photosynthetic pigment content, inhibition on quantum production and electron transport in PSII. It can be deduced that initial acid rain cannot enhance C. camphora tolerance to the following HT, and the impacts of the two stresses will depend on the pH of acid rain.