Regulation of chlorothalonil degradation by molecular hydrogen.

Pesticides can accumulate throughout the food chain to potentially endanger human health. Although molecular hydrogen (H2) is widely used in industry and medicine, its application in agriculture is just beginning. This study showed that H2 enhances the degradation of the fungicide chlorothalonil (CHT) in plants, but does not reduce its antifungal efficacy. Pharmacological evidence confirmed the contribution of H2-stimulated brassinosteroids (BRs) in the above responses. The genetic increased endogenous H2 with overexpression of hydrogenase 1 gene (CrHYD1) from Chlamydomonas reinhardtii in Arabidopsis not only increased BRs levels, but also eventually intensified the degradation of CHT. Expression of genes encoding some enzymes responsible for detoxification in tomato and Arabidopsis were also stimulated. Contrasting responses were observed after the pharmacological removal of endogenous BR. We further proved that H2 control of CHT degradation was relatively universal, with at least since its degradation in Chinese cabbage, cucumber, radish, alfalfa, rice, and rapeseed were differentially enhanced by H2. Collectively, above results clearly indicated that both exogenously and endogenously applied with H2 could stimulate degradation of CHT partially via BR-dependent detoxification. These results may open a new window for environmental-friendly hydrogen-based agriculture.