Li Wing-Yen Francisca, Wong Fuk-Ling, Tsai Sau-Na, Phang Tsui-Hung, Shao Guihua, Lam Hon-Ming
Department of Biology, The Chinese University of Hong Kong, Hong Kong Special Administrative Region (SAR), China.
Plant Cell Environ. 2006 Jun;29(6):1122-37. doi: 10.1111/j.1365-3040.2005.01487.x.
Genes encoding ion transporters that regulate ion homeostasis in soybean have not been carefully investigated. Using degenerate primers, we cloned a putative chloride channel gene (GmCLC1) and a putative Na+/H+ antiporter gene (GmNHX1) from soybean. Confocal microscopic studies using yellow fluorescent fusion proteins revealed that GmCLC1 and GmNHX1 were both localized on tonoplast. The expressions of GmCLC1 and GmNHX1 were both induced by NaCl or dehydration stress imposed by polyethylene glycol (PEG). Using mitochondrial integrity and cell death as the damage indicators, a clear alleviation under NaCl stress (but not PEG stress) was observed in both GmCLC1 and GmNHX1 transgenic cells. Using fluorescent dye staining and quenching, respectively, a higher concentration of chloride ion (Cl-) or sodium ion (Na+) was observed in isolated vacuoles in the cells of GmCLC1 and of GmNHX1 transgenic lines. Our result suggested that these vacuolar-located ion transporters function to sequester ions from cytoplasm into vacuole to reduce its toxic effects.
调控大豆离子稳态的离子转运蛋白编码基因尚未得到深入研究。我们使用简并引物从大豆中克隆了一个假定的氯离子通道基因（GmCLC1）和一个假定的Na+/H+反向转运蛋白基因（GmNHX1）。利用黄色荧光融合蛋白进行的共聚焦显微镜研究表明，GmCLC1和GmNHX1均定位于液泡膜。GmCLC1和GmNHX1的表达均受NaCl或聚乙二醇（PEG）引起的脱水胁迫诱导。以线粒体完整性和细胞死亡作为损伤指标，在GmCLC1和GmNHX1转基因细胞中均观察到在NaCl胁迫下（而非PEG胁迫下）损伤明显减轻。分别使用荧光染料染色和淬灭方法，在GmCLC1和GmNHX1转基因系细胞的分离液泡中观察到较高浓度的氯离子（Cl-）或钠离子（Na+）。我们的结果表明，这些定位于液泡的离子转运蛋白的功能是将离子从细胞质隔离到液泡中以降低其毒性作用。
