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Hydrogen Peroxide Is Involved in Methane-Alleviated Cadmium Toxicity in Alfalfa (<i>Medicago sativa</i> L.) Seedlings by Enhancing Cadmium Chelation onto Root Cell Walls
oleh: Yingying Zhao, Jie Yang, Feiyan Jiang, Gan Zhao
Format: | Article |
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Diterbitkan: | MDPI AG 2024-09-01 |
Deskripsi
Although previous studies have demonstrated that methane (CH<sub>4</sub>) can mitigate the toxicity of cadmium (Cd) in alfalfa seedlings, the CH<sub>4</sub>-rich water used in these studies may create hypoxic conditions, potentially influencing the experimental outcomes. Therefore, this study aimed to investigate whether CH<sub>4</sub> can reduce Cd toxicity in alfalfa seedlings without the interference of hypoxia and to analyze its underlying mechanisms. Here, it was observed that supplementing oxygen with saturated CH<sub>4</sub>-rich water can significantly alleviate the inhibition of 75 μM CdCl<sub>2</sub> on the growth of alfalfa (<i>Medicago sativa</i> L.) seedlings. Less Cd accumulation was also observed in both root and shoot parts, which could be explained by the CH<sub>4</sub>-altered cell wall components in alfalfa seedling roots, including covalent and ionic soluble pectin, and the degree of demethylation in pectin, thus enabling a higher proportion of Cd binding to the cell walls and reducing the entry of Cd into the cells. The above actions of CH<sub>4</sub> were accompanied by an increase in hydrogen peroxide (H<sub>2</sub>O<sub>2</sub>) content and NADPH oxidase activity, which could be blocked by the addition of the NADPH oxidase inhibitor diphenylene iodonium (DPI). Taken together, these results implied that exogenously applied CH<sub>4</sub> could alleviate Cd toxicity in alfalfa seedlings by enhancing Cd chelation onto the root cell walls, which might be closely associated with NADPH oxidase-dependent H<sub>2</sub>O<sub>2</sub> signals. These findings could provide insight into the mechanism through which CH<sub>4</sub> alleviates Cd toxicity in alfalfa plants.