Abstract
Objective: The widespread use of benzotriazole (BTA) has raised concerns about its potential risks to living organisms. However, the toxic effects of BTA on plants remain unclear. Thus, leaves of rice seedlings were employed as the tested materials in the current experiments. The objective was to investigate the toxicological effects of BTA on the photosynthesis and antioxidant systems in rice seedlings. Methods: The rice seedlings at the four-leaf stage were subjected to treatments by adding BTA into the nutrient solutions. The tested concentrations of BTA were set at 0, 1.5, 2.5, 5, and 10 mg/L. Results: The results showed that 1.5 mg/L BTA increased chlorophyll (Chl) content and net photosynthetic rate (Pn), accompanied by upregulation of atpA, atpB, psaB, and psbA genes. In contrast, 5 to 10 mg/L BTA stimulated excessive generation of superoxide anion (O(2)·(-)), enhanced the activities of NADPH oxidase, superoxide dismutase (SOD) and catalase (CAT) isozymes, and reduced Chl content, Pn, and stomatal conductance (Gs). Simultaneously, such treatments suppressed the expression of atpB, psbA, and RbcS genes. In addition, compared to the control, the products of 70 kDa heat shock proteins (HSP70) were apparently enhanced with the increase of BTA. Conclusions: This study demonstrated that the effects of BTA on the photosynthesis and antioxidant systems of rice seedlings exhibited a concentration-dependent response, with low concentrations (1.5 mg/L) improving photosynthesis, while high concentrations (5 to 10 mg/L) induced oxidative stress and photosynthetic damage. Furthermore, the activation of SOD and CAT isozymes, along with HSP70 induction, may contribute to mitigating BTA toxicity.