Zhao Yingying, Yang Jie, Jiang Feiyan, Zhao Gan
College of Life and Health Sciences, Anhui Science and Technology University, Chuzhou 233100, China.
College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China.
Plants (Basel). 2024 Sep 21;13(18):2639. doi: 10.3390/plants13182639.
Although previous studies have demonstrated that methane (CH) can mitigate the toxicity of cadmium (Cd) in alfalfa seedlings, the CH-rich water used in these studies may create hypoxic conditions, potentially influencing the experimental outcomes. Therefore, this study aimed to investigate whether CH 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-rich water can significantly alleviate the inhibition of 75 μM CdCl on the growth of alfalfa ( L.) seedlings. Less Cd accumulation was also observed in both root and shoot parts, which could be explained by the CH-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 were accompanied by an increase in hydrogen peroxide (HO) 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 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 HO signals. These findings could provide insight into the mechanism through which CH alleviates Cd toxicity in alfalfa plants.
尽管先前的研究表明，甲烷（CH）可以减轻镉（Cd）对苜蓿幼苗的毒性，但这些研究中使用的富含CH的水可能会造成缺氧条件，从而可能影响实验结果。因此，本研究旨在探究CH能否在无缺氧干扰的情况下降低苜蓿幼苗中的Cd毒性，并分析其潜在机制。在此观察到，用饱和富含CH的水补充氧气可显著减轻75 μM CdCl对苜蓿（L.）幼苗生长的抑制作用。在根和地上部分也观察到较少的Cd积累，这可以通过苜蓿幼苗根中CH改变的细胞壁成分来解释，包括共价和离子可溶性果胶，以及果胶中的去甲基化程度，从而使更高比例的Cd与细胞壁结合并减少Cd进入细胞。CH的上述作用伴随着过氧化氢（HO）含量和NADPH氧化酶活性的增加，而添加NADPH氧化酶抑制剂二苯基碘鎓（DPI）可以阻断这种增加。综上所述，这些结果表明，外源施用CH可以通过增强Cd在根细胞壁上的螯合作用来减轻苜蓿幼苗中的Cd毒性，这可能与NADPH氧化酶依赖性HO信号密切相关。这些发现可以为CH减轻苜蓿植物中Cd毒性的机制提供见解。
