College of Resources, Sichuan Agricultural University, Chengdu, 611130, China.
Department of Experimental Biology, Faculty of Science, Masaryk University, Kotlářská 2, 611 37, Brno, Czech Republic.
Chemosphere. 2021 Apr;268:129339. doi: 10.1016/j.chemosphere.2020.129339. Epub 2020 Dec 16.
Abscisic acid (ABA) play a crucial role in plant acclimation to heavy-metals stresses. Nevertheless, the effects of ABA on long-distance transport and its consequences for cadmium (Cd) accumulation are insufficiently understood. Here, we investigated the effects of ABA on the development of the whole-plant water transport pathway and implications for Cd uptake and transport to the shoot of Sedum alfredii. Exposure to Cd stimulated the production of endogenous ABA levels in the non-hyperaccumulating ecotype (NHE), but not in the hyperaccumulating ecotype (HE). Increased ABA levels in NHE significantly reduced aquaporin expressions in roots, the number of xylem vessel in stem, dimensions and densities of stomata in leaves, but induced leaf osmotic adjustment. Furthermore, the ABA-driven modifications in NHE plants showed typically higher sensitivity to ABA content in leaves compared to HE, illustrating ecotype-specific responses to ABA level. In NHE, the ABA-mediated modifications primarily affected the xylem transport of Cd ions and, at the cost of considerable water delivery limitations, significantly reduced delivery of Cd ions to shoots. In contrast, maintenance of low ABA levels in HE failed to t limit transpiration rates and maximized Cd accumulation in shoots. Our results demonstrated that ABA regulates Cd hyperaccumulation of S. alfredii through specific modifications in the water transport continuum.
脱落酸 (ABA) 在植物适应重金属胁迫中起着至关重要的作用。然而，ABA 对长距离运输的影响及其对镉 (Cd) 积累的后果还不够了解。在这里，我们研究了 ABA 对整个植物水分运输途径的发育以及对 Cd 吸收和向拟南芥地上部分运输的影响。暴露于 Cd 会刺激非超积累型生态型（NHE）中内源性 ABA 水平的产生，但不会刺激超积累型生态型（HE）中内源性 ABA 水平的产生。NHE 中 ABA 水平的升高显著降低了根中的水通道蛋白表达、茎中的木质部导管数量、叶片中气孔的尺寸和密度，但诱导了叶片的渗透调节。此外，与 HE 相比，NHE 中 ABA 驱动的修饰对叶片中 ABA 含量表现出更高的敏感性，这表明 ABA 水平存在生态型特异性响应。在 NHE 中，ABA 介导的修饰主要影响 Cd 离子的木质部运输，并且由于水输送的限制相当大，显著减少了 Cd 离子向地上部分的输送。相比之下，HE 中低 ABA 水平的维持未能限制蒸腾速率，并使 Cd 在地上部分的积累最大化。我们的结果表明，ABA 通过对水运输连续体的特定修饰来调节 S.alfredii 对 Cd 的超积累。
