The Vacuolar Na+/H+ Antiporter Gene SsNHX1 from the Halophyte Salsola soda Confers Salt Tolerance in Transgenic Alfalfa (Medicago sativa L.)
The Vacuolar Na+/H+ Antiporter Gene SsNHX1 from the Halophyte Salsola soda Confers Salt Tolerance in Transgenic Alfalfa (Medicago sativa L.)
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DOI：
10.1007/s11105-010-0224-y
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发表时间：
2011-06-01
影响因子：
2.1
通讯作者：
Liu, Lixia
中科院分区：
文献类型：
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作者：
Li, Wangfeng;Wang, Deli;Liu, Lixia
利用cDNA末端快速扩增法从盐生植物猪毛菜（Salsolasona）中克隆到一个液泡Na+/H+逆向转运蛋白基因（SsNHX 1）。在SsNHX 1推导的氨基酸序列中发现了植物液泡Na+/H+逆向转运蛋白的高度保守区域，包括阿米洛利结合结构域、NHE（Na+/H+交换）结构域和12个跨膜片段。液泡膜Na+/H+反向转运蛋白的多重比对表明，SsNHX 1与其它植物液泡膜Na+/H+反向转运蛋白具有较高的同源性。系统进化分析表明，SsNHX 1属于液泡膜Na+/H+逆向转运蛋白家族。综上所述，这些结果表明，SsNHX 1是液泡Na+/H+逆向转运蛋白家族的一个新成员。SsNHX 1基因在紫花苜蓿（Medicago sativa L.）增强了转基因苜蓿的耐盐性，其可以在高浓度的NaCl（高达400 mM）中生长超过50天。这是转基因植物中报道的最高水平的耐盐性。通过对转基因苜蓿和野生型苜蓿叶片Na+、K+含量、超氧化物歧化酶活性、电解质渗漏率和脯氨酸含量等生理特性的进一步分析，发现外源Na+/H+逆向转运蛋白将叶片细胞质中的大量Na+转运到液泡中，从而避免了Na+对转基因苜蓿细胞的毒害作用。
A putative vacuolar Na+/H+ antiporter gene (SsNHX1) was isolated from the halophyte Salsola soda using the rapid amplification of cDNA ends method. Highly conserved regions of plant vacuolar Na+/H+ antiporter, including amiloride-binding domain, NHE (Na+/H+ exchange) domain, and 12 transmembrane segments, were found in the deduced amino acid sequence of SsNHX1. Multiple alignments of vacuolar Na+/H+ antiporters showed that SsNHX1 shared high identity with other plant vacuolar Na+/H+ antiporters. Phylogenetic relationship analysis indicated that SsNHX1 was clustered into the vacuolar Na+/H+ antiporter group. Taken together, these results suggest that SsNHX1 is a new member of the vacuolar Na+/H+ antiporter family. The effective expression of SsNHX1 in alfalfa (Medicago sativa L.) enhanced the salt tolerance of transgenic alfalfa which could grow in high concentrations of NaCl (up to 400 mM) over 50 days. This was the highest level of salt tolerance reported in transgenic plants. A further analysis of the physiological characteristics of transgenic and wild-type plants, including the Na+ and K+ contents, superoxide dismutase activity, the rate of electrolyte leakage, and the proline content, showed that large amounts of Na+ in the cytoplasm of leaves were transported into vacuoles by the exogenous Na+/H+ antiporter, which averted the toxic effects of Na+ to the cell of transgenic alfalfa.