Functional analysis of CAX2-like transporters isolated from two ecotypes of Sedum alfredii
Functional analysis of CAX2-like transporters isolated from two ecotypes of Sedum alfredii
复制标题
从两种生态型景天中分离出的类 CAX2 转运蛋白的功能分析
DOI：
10.1007/s10535-015-0557-3
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发表时间：
2016
影响因子：
1.5
通讯作者：
Yang X. E.
中科院分区：
文献类型：
--
作者：
Zhang M.;Zhang J.;Lu L. L.;Zhu Z. Q.;Yang X. E.
从东南景天（Sedum alfredii Hance）的Zn/Cd超积累生态型（HE）和非超积累生态型（NHE）中分离到两个编码类CAX 2蛋白的基因，分别命名为SaCAX 2 h和SaCAX 2n。SaCAX 2 h：eGFP和SaCAX 2n：eGFP蛋白定位于烟草表皮细胞和酵母突变体的液泡膜。SaCAX 2 h或SaCAX 2n在Δ zrc 1酵母突变体中的异源表达增加了酵母细胞中的Cd含量。酵母互补试验还表明，这两种转运蛋白都能抑制K667酵母突变株对Ca和Mn的敏感性，并能促进Ca和Mn的积累。在镉胁迫下，这两个基因的表达模式不同。Cd处理后，SaCAX 2 h在根中的转录水平下调，在芽中的转录水平上调，SaCAX 2n在芽中的转录水平下调。此外，SaCAX 2 h的过表达增强了烟草植株中金属的积累。结果表明，转基因植株地上部Cd含量增加17- 19%，根中Cd含量增加31 - 36%，地上部Ca含量增加31- 32%，地上部Mn含量增加60- 79%，根中Mn含量增加22- 29%。这些结果表明，SaCAX 2 h负责将Ca和Mn固定到液泡中，并且过量表达SaCAX 2 h增强了转基因烟草中Cd的积累。
Two genes encoding CAX2-like proteins were isolated from a Zn/Cd hyperaccumulating ecotype (HE) and nonhyperaccumulating ecotype (NHE) of Sedum alfredii Hance, and they were named SaCAX2h and SaCAX2n, respectively. Both SaCAX2h:eGFP and SaCAX2n:eGFP proteins were localized to the vacuolar membrane of tobacco epidermal cells and yeast mutants. Heterologous expression of SaCAX2h or SaCAX2n in the Δzrc1 yeast mutant increased Cd content in yeast cells. Yeast complementary assay also revealed that both the transporters could suppress Ca and Mn hypersensitivity and enhance Ca and Mn accumulation in a K667 yeast mutant. The expression patterns of the two genes were different under the Cd treatment. Transcription of SaCAX2h was down-regulated in roots and up-regulated in shoots whereas transcription of SaCAX2n was down-regulated in shoots after the exposition to Cd. Furthermore, over-expression of SaCAX2h enhanced metal accumulation in the tobacco plants. The Cd content increased by 17–19 % in shoots and 31–36 % in roots; the Ca content of the transgenic plants increased by 31–32 % in shoots, and the Mn content increased by 60–79 % in shoots and 22–29 % in roots. These results indicate that SaCAX2h was responsible for Ca and Mn sequestration into vacuoles, and over-expression of SaCAX2h enhanced Cd accumulation in the transgenic tobacco.