State Key Laboratory of Plant Physiology and Biochemistry, Department of Plant Sciences, College of Biological Sciences, China Agricultural University, 100193 Beijing, China.
Plant Mol Biol. 2010 Jul;73(4-5):467-79. doi: 10.1007/s11103-010-9633-4. Epub 2010 Apr 1.
Salt stress leads to a stress response, called the unfolded protein response (UPR), in the endoplasmic reticulum (ER). UPR is also induced in a wide range of organisms by zinc deficiency. However, it is not clear whether regulation of zinc levels is involved in the initiation of the UPR in plant response to salt stress. In this study, a putative zinc transporter, ZTP29, was identified in Arabidopsis thaliana. ZTP29 localizes to the ER membrane and is expressed primarily in hypocotyl and cotyledon tissues, but its expression can be induced in root tissue by salt stress. T-DNA insertion into the ZTP29 gene led to NaCl hypersensitivity in seed germination and seedling growth, leaf etiolation, and widening of cells in the root elongation zone. In addition, in ztp29 mutant plants, salt stress-induced upregulation of the UPR pathway genes BiP2 and bZIP60 was inhibited. Furthermore, under conditions of salt stress, upregulation of BiP2 and bZIP60 was inhibited by treatment with high concentrations of zinc in both control and ztp29 plants. However, zinc chelation restored salt stress-induced BiP2 and bZIP60 upregulation in ztp29 mutant plants. These experimental results suggest that ZTP29 is involved in the response to salt stress, perhaps through regulation of zinc levels required to induce the UPR pathway.
盐胁迫会在内质网（ER）中引发应激反应，称为未折叠蛋白反应（UPR）。锌缺乏也会在广泛的生物体中诱导 UPR。然而，目前尚不清楚调节锌水平是否参与植物对盐胁迫的 UPR 的启动。在这项研究中，在拟南芥中鉴定出一种假定的锌转运蛋白 ZTP29。ZTP29 定位于内质网膜，主要在下胚轴和子叶组织中表达，但可以被盐胁迫诱导在根组织中表达。T-DNA 插入 ZTP29 基因导致 NaCl 对种子萌发和幼苗生长、叶片白化和根伸长区细胞变宽的敏感性增加。此外，在 ztp29 突变体植物中，盐胁迫诱导的 UPR 途径基因 BiP2 和 bZIP60 的上调受到抑制。此外，在盐胁迫条件下，高浓度锌处理抑制了对照和 ztp29 植物中 BiP2 和 bZIP60 的上调。然而，锌螯合剂恢复了 ztp29 突变体植物中盐胁迫诱导的 BiP2 和 bZIP60 的上调。这些实验结果表明，ZTP29 参与了对盐胁迫的反应，可能是通过调节诱导 UPR 途径所需的锌水平。
