College of Resources, Sichuan Agricultural University, Chengdu 611130, China.
Czech Academy of Sciences, Biology Centre, Institute of Plant Molecular Biology, Laboratory of Plant Biophysics & Biochemistry, Branišovská 1160/31, České Budějovice 370 05, Czech Republic.
Ecotoxicol Environ Saf. 2024 Apr 15;275:116272. doi: 10.1016/j.ecoenv.2024.116272. Epub 2024 Apr 1.
This study investigated the influence of Cd (25 µM) on Zn accumulation in a hyperaccumulating (HE) and a non-hyperaccumulating (NHE) ecotype of Sedum alfredii Hance at short-term supply of replete (Zn5, 5 µM) and excess (Zn400, 400 µM) Zn. Cd inhibited Zn accumulation in both ecotypes, especially under Zn400, in organs with active metal sequestration, i.e. roots of NHE and shoots of HE. Direct biochemical Cd/Zn competition at the metal-protein interaction and changes in transporter gene expression contributed to the observed accumulation patterns in the roots. Specifically, in HE, Cd stimulated SaZIP4 and SaPCR2 under Zn5, but downregulated SaIRT1 and SaZIP4 under Zn400. However, Cd downregulated related transporter genes, except for SaNRAMP1, in NHE, irrespective of Zn. Cadmium stimulated casparian strip (CSs) development in NHE, as part of the defense response, while it had a subtle effect on the (CS) in HE. Moreover, Cd delayed the initiation of the suberin lamellae (SL) in HE, but stimulated SL deposition in NHE under both Zn5 or Zn400. Changes in suberization were mainly ascribed to suberin-biosynthesis-related genes and hormonal signaling. Altogether, Cd regulated Zn accumulation mainly via symplasmic and transmembrane transport in HE, while Cd inhibited both symplasmic and apoplasmic Zn transport in NHE.
本研究探讨了 Cd（25μM）对超积累（HE）和非超积累（NHE）生态型Sedum alfredii Hance 在短期充足（Zn5，5μM）和过量（Zn400，400μM）Zn 供应下 Zn 积累的影响。Cd 抑制了两种生态型的 Zn 积累，尤其是在 Zn400 条件下，在具有主动金属螯合作用的器官中，即 NHE 的根和 HE 的茎。金属蛋白相互作用中的直接生化 Cd/Zn 竞争和转运蛋白基因表达的变化导致了在根部观察到的积累模式。具体而言，在 HE 中，Cd 在 Zn5 下刺激 SaZIP4 和 SaPCR2，但在 Zn400 下下调 SaIRT1 和 SaZIP4。然而，Cd 下调了相关转运蛋白基因，除了 SaNRAMP1，在 NHE 中，与 Zn 无关。Cd 刺激 NHE 中的 Casparian 条纹（CS）发育，作为防御反应的一部分，而对 HE 中的 CS 几乎没有影响。此外，Cd 延迟了 HE 中木质素片层（SL）的起始，但在 Zn5 或 Zn400 下刺激 NHE 中 SL 的沉积。木质化的变化主要归因于木质素合成相关基因和激素信号。总的来说，Cd 通过 HE 中的共质体和跨膜运输来调节 Zn 的积累，而在 NHE 中，Cd 抑制了共质体和质外体 Zn 的运输。
