Characterization of a novel glycinebetaine/proline transporter gene expressed in the mestome sheath and lateral root cap cells in barley
Characterization of a novel glycinebetaine/proline transporter gene expressed in the mestome sheath and lateral root cap cells in barley
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DOI：
10.1007/s00425-010-1155-4
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发表时间：
2010-06-01
期刊：
影响因子：
4.3
通讯作者：
Takabe, Tetsuko
中科院分区：
文献类型：
--
作者：
Fujiwara, Takashi;Mitsuya, Shiro;Takabe, Tetsuko
甘氨酸甜菜碱（GB）的积累是逆境盐胁迫条件的适应策略之一。尽管已经证明大麦植物在盐胁迫下积累GB，并且针对GB合成进行了各种研究，但其转运机制仍不清楚。在这项研究中，我们鉴定了一个新基因 HvProT2，它编码来自大麦植物的大麦 GB/脯氨酸转运蛋白。酵母（酿酒酵母）突变体中的异源表达表明，HvProT2 对 GB 的亲和力最高，对脯氨酸的亲和力中等，对 γ-氨基丁酸的亲和力最低。 HvProT2 和绿色荧光蛋白融合体在洋葱表皮细胞中的瞬时表达表明 HvProT2 位于质膜上。采用半定量逆转录聚合酶链式反应分析对HvProT2 mRNA水平进行相对定量，结果表明HvProT2在叶和根中均组成型表达，且老叶中的表达水平高于新叶和根。此外，我们发现HvProT2在间质鞘和侧根帽细胞中表达。我们讨论了 HvProT2 可能参与盐胁迫耐受性。
The accumulation of glycinebetaine (GB) is one of the adaptive strategies to adverse salt stress conditions. Although it has been demonstrated that barley plants accumulate GB in response to salt stress and various studies focused on GB synthesis were performed, its transport mechanism is still unclear. In this study, we identified a novel gene, HvProT2, encoding Hordeum vulgare GB/proline transporter from barley plants. Heterologous expression in yeast (Saccharomyces cerevisiae) mutant demonstrated that the affinity of HvProT2 was highest for GB, intermediate for proline and lowest for gamma-aminobutyric acid. Transient expression of fusions of HvProT2 and green fluorescent protein in onion epidermal cells revealed that HvProT2 is localized at the plasma membrane. Relative quantification of mRNA level of HvProT2 using semi-quantitative reverse transcription-polymerase chain reaction analysis showed that HvProT2 is constitutively expressed in both leaves and roots, and the expression level was higher in old leaves than young leaves and roots. Moreover, we found that HvProT2 was expressed in the mestome sheath and lateral root cap cells. We discussed the possible involvement of HvProT2 for salt stress tolerance.