Zhejiang Academy of Agricultural Sciences, Hangzhou, Zhejiang 310021, PR China; Key Laboratory for Subtropical Wetland Ecosystem Research of MOE, College of the Environment and Ecology, Xiamen University, Xiamen, Fujian 361102, PR China.
Key Laboratory for Subtropical Wetland Ecosystem Research of MOE, College of the Environment and Ecology, Xiamen University, Xiamen, Fujian 361102, PR China; Houji Laboratory in Shanxi Province, Shanxi Agricultural University, Taiyuan, Shanxi 030000, PR China.
J Hazard Mater. 2024 Dec 5;480:136210. doi: 10.1016/j.jhazmat.2024.136210. Epub 2024 Oct 18.
Heavy metal cadmium (Cd) is toxic to organisms. Mulberry (Morus alba L.) is a fast-growing perennial that is also an economical Cd phytoremediation material with large biomass. However, the molecular mechanisms underlying its Cd tolerance remain unclear. Here, we reveal the physiological and molecular mechanisms underlying Cd toxicity under varying calcium (Ca) treatments. First, under low-Ca treatment (0.1 mM Ca), mulberry growth was severely inhibited and the root surface structure was damaged by Cd stress. Second, electrophysiological data demonstrated that 0.1 mM Ca induced an increased Cd influx, leading to its accumulation in the entire root and root cell walls. Third, high-Ca treatment (10 mM Ca) largely alleviated growth inhibition, activated antioxidant enzymes, increased Ca content, decreased Cd flux, and inhibited Cd uptake by roots. Finally, 0.1 mM Ca resulted in the activation of metal transporters and the disruption of Ca signaling-related gene expression, which facilitated Cd accumulation in the roots, aggravating oxidative stress. These adverse effects were reversed by treatment with 10 mM Ca. This study preliminarily revealed the mechanism by which varying Ca levels regulate Cd uptake and accumulation in mulberry roots, provided an insight into the interrelationships between Ca and Cd in the ecological and economic tree mulberry and offered a theoretical basis for Ca application in managing Cd pollution.
重金属镉（Cd）对生物有毒。桑树（Morus alba L.）是一种生长迅速的多年生植物，也是一种具有较大生物量的经济 Cd 植物修复材料。然而，其 Cd 耐受的分子机制尚不清楚。在这里，我们揭示了不同钙（Ca）处理下 Cd 毒性的生理和分子机制。首先，在低钙处理（0.1 mM Ca）下，Cd 胁迫严重抑制桑树生长，破坏根表面结构。其次，电生理数据表明，0.1 mM Ca 诱导 Cd 内流增加，导致其在整个根部和根细胞壁中积累。第三，高钙处理（10 mM Ca）在很大程度上缓解了生长抑制，激活了抗氧化酶，增加了 Ca 含量，降低了 Cd 通量，并抑制了根部对 Cd 的吸收。最后，0.1 mM Ca 导致金属转运蛋白的激活和 Ca 信号相关基因表达的破坏，这有利于 Cd 在根部的积累，加剧了氧化应激。这些不利影响在 10 mM Ca 处理下得到了逆转。本研究初步揭示了不同 Ca 水平调节桑树根部 Cd 吸收和积累的机制，深入了解了生态和经济树种桑树中 Ca 和 Cd 之间的相互关系，为 Ca 在管理 Cd 污染中的应用提供了理论依据。
