Hydrogen gas (H₂) has a possible signaling role in many developmental and adaptive plant responses, including mitigating the harmful effects of cadmium (Cd) uptake from soil. We used electrophysiological and molecular approaches to understand how H₂ ameliorates Cd toxicity in pak choi (Brassica campestris ssp. chinensis). Exposure of pak choi roots to Cd resulted in a rapid increase in the intracellular H₂ production. Exogenous application of hydrogen-rich water (HRW) resulted in a Cd-tolerant phenotype, with reduced net Cd uptake and accumulation. We showed that this is dependent upon the transport of calcium ions (Ca²⁺) across the plasma membrane and apoplastic generation of hydrogen peroxide (H₂O₂) by respiratory burst oxidase homolog (BcRbohD). The reduction in root Cd uptake was associated with the application of exogenous HRW or H₂O₂. This reduction was abolished in the iron-regulated transporter1 (Atirt1) mutant of Arabidopsis (Arabidopsis thaliana), and pak choi pretreated with HRW showed decreased BcIRT1 transcript levels. Roots exposed to HRW had rapid Ca²⁺ influx, and Cd-induced Ca²⁺ leakage was alleviated. Two Ca²⁺ channel blockers, gadolinium ion (Gd³⁺) and lanthanum ion (La³⁺), eliminated the HRW-induced increase in BcRbohD expression, H₂O₂ production, and Cd²⁺ influx inhibition. Collectively, our results suggest that the Cd-protective effect of H₂ in plants may be explained by its control of the plasma membrane-based NADPH oxidase encoded by RbohD, which operates upstream of IRT1 and regulates root Cd uptake at both the transcriptional and functional levels. These findings provide a mechanistic explanation for the alleviatory role of H₂ in Cd accumulation and toxicity in plants.

氢气（H ₂）在许多发育和适应性植物反应中可能具有信号作用，包括减轻土壤对镉（Cd）的有害吸收。我们使用电生理和分子的方法来了解如何^ h ₂改善镉毒性青菜（的芸苔属野油菜 亚种对虾）。白菜根暴露于Cd导致细胞内H ₂产量快速增加。外源施用富氢水（HRW）导致耐Cd的表型，净Cd吸收和积累减少。我们证明了这取决于钙离子（Ca ²⁺）跨质膜，并通过呼吸爆发氧化酶同源物（BcRbohD）质外生成过氧化氢（H ₂ O ₂）。根部镉吸收的减少与外源HRW或H ₂ O ₂的施用有关。这种减少在拟南芥（Arabidopsis thaliana）的铁调节转运蛋白1（Atirt1）突变体中被取消，用HRW预处理的青菜显示BcIRT1转录水平降低。暴露于HRW的根部具有快速的Ca ²⁺流入，并且减轻了Cd诱导的Ca ²⁺泄漏。两种Ca ²⁺通道阻滞剂，lin离子（Gd ³⁺）和镧离子（La ³⁺）消除了HRW诱导的BcRbohD表达增加，H ₂ O ₂产生和Cd ^2+内流抑制。总体而言，我们的结果表明，H ₂对植物中Cd的保护作用可能是由其控制由RbohD编码的质膜NADPH氧化酶控制的，该酶在IRT1的上游运行，并在转录和功能上调节根对Cd的吸收。水平。这些发现为H ₂在植物中Cd积累和毒性中的缓解作用提供了机械解释。