Hydrogen-rich water alleviates cadmium stress in Chinese flowering cabbage by enhancing antioxidant capacity, improving photosynthesis, and reducing cadmium uptake.

Hydrogen-Rich Water (HRW) is a new environmentally friendly plant growth regulator that can effectively mitigate various abiotic stresses in plants. This study demonstrated that HRW significantly alleviated cadmium (Cd) stress in Chinese flowering cabbage. Compared to Cd treatment alone, Cd+HRW greatly enhanced the growth parameters and photosynthetic characteristics of the Chinese flowering cabbage. Under Cd+HRW stress, HRW notably reduced the malondialdehyde (MDA) content in shoots. Concurrently, HRW increased the activity of antioxidant enzymes, including peroxidase (POD), superoxide dismutase (SOD), ascorbate peroxidase (APX), and catalase (CAT), with Cd stress. And the levels of hydrogen peroxide (H2O2) and superoxide anion (O2 -) generated by Cd stress in the Chinese flowering cabbage were significantly reduced by exogenous HRW. These findings collectively suggested that HRW boosts the antioxidant capacity of Chinese flowering cabbage under Cd stress. Additionally, the levels of nonenzymatic antioxidants such as ascorbic acid (AsA) and glutathione (GSH) were also remarkably improved by HRW. The detection results of Cd concentration revealed that Cd concentrations of shoot and root were significantly lowered by HRW in the Chinese flowering cabbage seedlings. However, the Cd transport coefficient was not significantly affected by HRW. This suggested that HRW-reduced Cd accumulation may result from inhibiting the uptake of Cd by HRW in Chinese flowering cabbage. To further validate this conclusion, we analyzed the expression levels of genes related to Cd uptake and transport in the Chinese flowering cabbage. The results revealed that HRW+Cd significantly downregulated the expressions of related genes (BcIRT1, BcIRT2, BcNramp1, and BcZIP2) involved in Cd uptake compared to Cd treatment alone in the Chinese flowering cabbage. However, the transcript level of the genes related to Cd transportation were not significantly affected by HRW. Therefore, based on the above experimental results, we suggested that HRW alleviated Cd stress may be on account of enhancing the antioxidant capacity and reducing the Cd uptake of the Chinese flowering cabbages.