Characterization of a novel Na+/H+ antiporter gene InNHX2 and comparison of InNHX2 with InNHX1, which is responsible for blue flower coloration by increasing the vacuolar pH in the Japanese morning glory
Characterization of a novel Na+/H+ antiporter gene InNHX2 and comparison of InNHX2 with InNHX1, which is responsible for blue flower coloration by increasing the vacuolar pH in the Japanese morning glory
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DOI：
10.1093/pcp/pci028
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发表时间：
2005-02-01
影响因子：
4.9
通讯作者：
Iida, S
中科院分区：
文献类型：
--
作者：
Ohnishi, A;Fukada-Tanaka, S;Iida, S
野生型日本牵牛花（Ipomoea nit）的红紫色花蕾变成蓝色开放的花朵，并且花朵颜色的变化与花表皮细胞液泡pH值的增加相关。在液泡Na+/H+逆向转运蛋白InNHX 1基因缺陷的突变体中，液泡碱化仅部分发生，红紫色的芽变成紫色的开放的花。虽然大多数植物NHX基因的特点是一般表达在叶，茎和根和诱导的NaCl处理，InNHX 1基因主要表达在花开放前12小时左右的花肢。它在叶、茎和根中非常稀疏地表达，并且不响应于NaCl处理而发生诱导。这里.我们鉴定了一个新的液泡Na+/H+逆向转运蛋白基因InNHX 2，该基因在叶、茎和根中表达，并且响应于NaCl处理而被诱导。此外，在开花前不久的花肢中观察到相对较高的InNHX 2表达。我们还发现InNHX 1和InNHX 2蛋白都可以催化Na+和K+转运到液泡中。这些结果表明，InNHX 2执行双重功能：赋予植物耐盐性和促进花瓣中的部分液泡碱化。这意味着InNHX 2蛋白可能是负责将红紫色芽转化为馅饼开放的花朵部分增加液泡pH值的情况下，主要InNHX 1活动的组件之一。
The reddish-purple buds of the wild-type Japanese morning glory (Ipomoea nit) change into blue open flowers, and the shift in the flower coloration correlates with an increase in the vacuolar pH of the flower epidermal cell. In the mutant deficient in the InNHX1 gene for the vacuolar Na+/H+ antiporter, the vacuolar alkalization occurs only partially, and reddish-purple buds become purple open flowers. While most of the plant NHX genes characterized are generally expressed in leaves, stems and roots and induced by NaCl treatment, the InNHX1 gene is expressed predominantly in the flower limbs at around 12 h before flower opening. It is expressed very sparsly in leaves, stems and roots, and no induction occurs in response to NaCl treatment. Here. we identified a novel vacuolar Na+/H+ antiporter gene InNHX2, which is expressed in leaves, stems and roots and is induced in response to NaCl treatment. In addition, relatively higher expression of InNHX2 was observed in the flower limbs shortly before flower opening. We also discovered that both the InNHX1 and InNHX2 proteins can catalyze both Na+ and K+ transport into vacuoles. These results suggest that InNHX2 performs dual functions: to confer salt tolerance on the plant and to promote partial vacuolar alkalization in the petals. The implication is that the InNHX2 protein is probably one of the components responsible for converting reddish-purple buds into put-pie open flowers by partially increasing the vacuolar pH in the absence of major InNHX1 activity.