Luo Guang-Zuo, Wang Hui-Wen, Huang Jian, Tian Ai-Guo, Wang Yong-Jun, Zhang Jin-Song, Chen Shou-Yi
National Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, 100101 Beijing, China.
Plant Mol Biol. 2005 Nov;59(5):809-20. doi: 10.1007/s11103-005-1386-0.
Cation transport is thought to be an important process for ion homeostasis in plant cells. Here, we report that a soybean putative cation/proton antiporter GmCAX1 may be a mediator of this process. GmCAX1 is expressed in all tissues of the soybean plants but at a lower level in roots. Its expression was induced by PEG, ABA, Ca(2+), Na(+) and Li(+) treatments. The GmCAX1-GFP fusion protein was mainly localized in plasma membrane of the transgenic Arabidopsis plant cells and onion epidermal cells. Transgenic Arabidopsis plants overexpressing GmCAX1 accumulated less Na(+), K(+), and Li(+), and were more tolerant to elevated Li(+) and Na(+) levels during germination when compared with the controls. These results suggest that GmCAX1 may function as an antiporter for Na(+), K(+) and Li(+). Modulation of this antiporter may be beneficial for regulation of ion homeostasis and thus plant salt tolerance.
阳离子转运被认为是植物细胞中离子稳态的一个重要过程。在此，我们报道一种大豆推定的阳离子/质子反向转运蛋白GmCAX1可能是这一过程的介质。GmCAX1在大豆植株的所有组织中均有表达，但在根中的表达水平较低。其表达受聚乙二醇（PEG）、脱落酸（ABA）、钙离子（Ca²⁺）、钠离子（Na⁺）和锂离子（Li⁺）处理的诱导。GmCAX1 - 绿色荧光蛋白（GFP）融合蛋白主要定位于转基因拟南芥植物细胞和洋葱表皮细胞的质膜上。与对照相比，过表达GmCAX1的转基因拟南芥植株积累较少的钠离子、钾离子（K⁺）和锂离子，并且在萌发期间对升高的锂离子和钠离子水平具有更强的耐受性。这些结果表明，GmCAX1可能作为钠离子、钾离子和锂离子的反向转运蛋白发挥作用。调节这种反向转运蛋白可能有利于调节离子稳态，从而提高植物的耐盐性。
