Aix Marseille University, French Alternative Energies and Atomic Energy Commission (CEA), National Center for Scientific Research (CNRS), Bioscience and Biotechnology Institute of Aix-Marseille (BIAM), Laboratory of Signaling for the Adaptation to their Environment (SAVE), Saint-Paul-lez-Durance, France.
Laboratory of Research on Radionuclides Transfer Within Terrestrial Ecosystems (LR2T), Institute for Radiological Protection and Nuclear Safety (IRSN), Cadarache, France.
Physiol Plant. 2021 Nov;173(3):1230-1243. doi: 10.1111/ppl.13518. Epub 2021 Aug 26.
Understanding the molecular mechanisms that underlie cesium (Cs ) transport in plants is important to limit the entry of its radioisotopes from contaminated areas into the food chain. The potentially toxic element Cs , which is not involved in any biological process, is chemically closed to the macronutrient potassium (K ). Among the multiple K carriers, the high-affinity K transporters family HAK/KT/KUP is thought to be relevant in mediating opportunistic Cs transport. Of the 13 KUP identified in A. thaliana, only HAK5, the major contributor to root K acquisition under low K supply, has been functionally demonstrated to be involved in Cs uptake in planta. In the present study, we showed that accumulation of Cs increased by up to 30% in two A. thaliana mutant lines lacking KUP9 and grown under low K supply. Since further experiments revealed that Cs release from contaminated plants to the external medium is proportionally lower in the two kup9 mutant alleles, we proposed that KUP9 disruption could impair Cs efflux. By contrast, K status in kup9 mutants is not affected, suggesting that KUP9 disruption does not alter substantially K transport in experimental conditions used. The putative primary role of KUP9 in plants is further discussed.
了解铯（Cs）在植物中运输的分子机制对于限制其放射性同位素从污染地区进入食物链非常重要。Cs 是一种非必需的有毒元素，其化学性质与大量营养元素钾（K）相似。在多种 K 载体中，高亲和力 K 转运蛋白家族 HAK/KT/KUP 被认为与 Cs 的机会性转运有关。在拟南芥中鉴定出的 13 种 KUP 中，只有在低钾供应下对根系 K 吸收贡献最大的 HAK5 被证明在植物体内参与 Cs 的摄取。在本研究中，我们表明，在低钾供应下生长的两种缺乏 KUP9 的拟南芥突变体中，Cs 的积累增加了 30%。由于进一步的实验表明，在两个 kup9 突变等位基因中，受污染植物向外部介质释放的 Cs 比例较低，因此我们提出 KUP9 的缺失可能会损害 Cs 的外排。相比之下，kup9 突变体中的 K 状态不受影响，这表明在实验条件下，KUP9 的缺失不会显著改变 K 的运输。进一步讨论了 KUP9 在植物中的主要作用。
