Key Laboratory for Subtropical Wetland Ecosystem Research of MOE, College of the Environment and Ecology, Xiamen University, Xiamen, Fujian 361005, China.
Key Laboratory for Subtropical Wetland Ecosystem Research of MOE, College of the Environment and Ecology, Xiamen University, Xiamen, Fujian 361005, China; Houji Laboratory in Shanxi Province, Shanxi Agricultural University, Taiyuan, Shanxi 030000, China.
J Hazard Mater. 2024 Dec 5;480:135926. doi: 10.1016/j.jhazmat.2024.135926. Epub 2024 Sep 20.
Cadmium (Cd) pollution poses a significant ecological risk to mangrove ecosystems. Trehalose has excellent potential to mitigate the adverse effects of heavy metals. Unfortunately, the mechanisms related to trehalose-mediated heavy metal tolerance in plants remain elusive. In the present study, we firstly found that Cd induced the accumulation of trehalose and the differential expression of trehalose biosynthesis genes in the roots of mangrove plant Avicennia marina. Then, we found that the application of exogenous trehalose could alleviate the negative effects of Cd on A. marina by phenotypic observation. In addition, photosynthetic parameters and cellular ultrastructure analyses demonstrated that exogenous trehalose could improve the photosynthesis and stabilize the chloroplast and nuclear structure of the leaves of A. marina. Besides, exogenous trehalose could inhibit the Cd influx from the root to reduce the Cd content in A. marina. Subsequently, substrate sensitivity assay combined with ion uptake analysis using yeast cells showed that several trehalose biosynthesis genes may have a regulatory function for Cd transport. Finally, we further identified a positive regulatory factor, AmTPS6, which enhances the Cd tolerance in transgenic Arabidopsis thaliana. Taken together, these findings provide new understanding to the mechanism of Cd tolerance in mangrove A. marina at trehalose aspect and a theoretical basis for the conservation of mangroves in coastal wetlands.
镉（Cd）污染对红树林生态系统构成重大生态风险。海藻糖具有减轻重金属不利影响的巨大潜力。不幸的是，与植物中海藻糖介导的重金属耐受性相关的机制仍不清楚。在本研究中，我们首先发现 Cd 诱导了红树林植物海桑根中海藻糖的积累和海藻糖生物合成基因的差异表达。然后，我们发现外源海藻糖的应用可以通过表型观察减轻 Cd 对 A. marina 的负面影响。此外，光合参数和细胞超微结构分析表明，外源海藻糖可以改善 A. marina 的光合作用并稳定其叶片的叶绿体和核结构。此外，外源海藻糖可以抑制 Cd 从根部进入，从而降低 A. marina 中的 Cd 含量。随后，利用酵母细胞进行底物敏感性测定和离子摄取分析表明，几种海藻糖生物合成基因可能对 Cd 转运具有调节作用。最后，我们进一步鉴定了一个正调控因子 AmTPS6，它增强了转基因拟南芥对 Cd 的耐受性。总之，这些发现为海藻糖方面红树林 A. marina 对 Cd 耐受性的机制提供了新的认识，并为沿海湿地红树林的保护提供了理论依据。
