Coordinated responses of rice (Oryza sativa) to the stresses of benzotriazole ultraviolet stabilizers (BZT-UVs): Antioxidative system, photosynthetic activity, and metabolic regulation

Massive use of plastic products has caused their accumulation in soils, releasing large amounts of endogenous plastic additives (e.g., benzotriazole ultraviolet stabilizers, in short BZT-UVs) into terrestrial ecosystems. However, their plant toxicity is little known. Herein, we investigated the occurrence of BZT-UVs in contaminated farmland and selected three BZT-UV congeners to explore their toxic effects on the antioxidant, photosynthetic, and metabolic perturbation on rice (Oryza sativa). Results showed that the mean concentrations of ∑BZT-UVs in soil and plant samples were 180.7 ng/g dw and 156.4 ng/g dw, respectively. UV-P, UV-327 and UV-328 were the dominant BZT-UV congeners in both of soils and plants. Three BZT-UV congeners caused oxidative damages to rice in a dose-dependent manner, especially for UV-328. Functional genes involved in chlorophyll synthetases was inhibited by over 50 % under the stress of BZT-UVs, whereas those responsible for chlorophyll degradation were obviously promoted. The chlorophyll content was thus decreased, leading to a weakened photosynthesis system and an unbalanced carbon metabolism. The transcriptome and metabolome proved that the flux of carbohydrate metabolism and amino acid metabolism were obviously promoted in plants induced by BZT-UVs, which could inhibit the growth of rice. These findings offered insights into the coordinated responses of plants and advanced our understanding of potential ecological risks of BZT-UVs to terrestrial ecosystems.