Cadmium (Cd) is a toxic heavy metal that poses risks to crop production and food safety worldwide. This study evaluated whether manganese (Mn) addition could mitigate Cd toxicity and reduce Cd accumulation in barley seedlings. Hydroponically grown seedlings of Cd-tolerant (WSBZ) and Cd-sensitive (Dong17) barley cultivars were treated with 0.1 μM and 1 μM Cd as well as 0.2 mM Mn alone and in a combination with 0.1 or 1.0 μM Cd for 21 days. Cd exposure caused the dramatic alteration of growth and physiological parameters by disrupting chloroplast, and increased Cd accumulation in both genotypes. However, Mn addition markedly alleviated the negative impacts of all examined parameters caused by Cd stress. Cd addition enhanced expression of anti-oxidative enzyme related genes, including HvSOD, HvCAT, HvAPX, HvPOD in the two barley genotypes exposed to Cd stress. The expression analysis showed nearly all HvNRAMPs genes are dramatically up regulated by both Mn and Cd, with WSBZ having higher expression than Dong 17. Notably, HvNRAMP1 showed the highest expression due to Mn addition, highlighting its crucial role in Mn uptake and transportation in barley. Moreover, Cd stress and Mn addition increased and suppressed the expression of HvYSL5, HvHMA2 and HvHMA3, respectively. Conversely, the expression of HvYSL2, HvIRT1 and HvMTP8 was upregulated by both Mn and Cd treatments, with a further increase observed in the combined Cd and Mn treatments. It may be concluded that sufficient Mn supply is quite important for reducing Cd uptake and accumulation in plants.

中文翻译：

---

锰通过介导叶绿体完整性、抗氧化系统和 HvNRAMP 表达来增强大麦中镉的耐受性


镉 （Cd） 是一种有毒的重金属，对全球农作物生产和食品安全构成风险。本研究评价了添加锰 （Mn） 是否可以减轻大麦幼苗的 Cd 毒性并减少 Cd 积累。耐 Cd （WSBZ） 和 Cd 敏感 （Dong17） 大麦品种的水培幼苗用 0.1 μM 和 1 μM Cd 以及 0.2 mM Mn 单独处理以及与 0.1 或 1.0 μM Cd 组合处理 21 天。Cd 暴露通过破坏叶绿体导致生长和生理参数发生巨大改变，并增加两种基因型 Cd 的积累。然而，Mn 添加显着减轻了 Cd 应力引起的所有检查参数的负面影响。Cd 添加增强了暴露于 Cd 胁迫的两种大麦基因型中抗氧化酶相关基因的表达，包括 HvSOD 、 HvCAT 、 HvAPX 、 HvPOD 。表达分析显示，几乎所有 HvNRAMPs 基因都被 Mn 和 Cd 显著上调，其中 WSBZ 的表达高于 Dong 17。值得注意的是，由于 Mn 添加，HvNRAMP1 的表达最高，突出了它在大麦中 Mn 摄取和运输中的关键作用。此外，Cd 胁迫和 Mn 添加分别增加和抑制 HvYSL5 、 HvHMA2 和 HvHMA3 的表达。相反，HvYSL2 、 HvIRT1 和 HvMTP8 的表达在 Mn 和 Cd 处理下均上调，在 Cd 和 Mn 联合处理中观察到进一步增加。可以得出结论，充足的 Mn 供应对于减少植物中 Cd 的吸收和积累非常重要。