Low-affinity cation transporter (OsLCT1) regulates cadmium transport into rice grains
Low-affinity cation transporter (OsLCT1) regulates cadmium transport into rice grains
复制标题
DOI：
10.1073/pnas.1116531109
复制
发表时间：
2011-12-27
影响因子：
11.1
通讯作者：
Fujiwara, Toru
中科院分区：
文献类型：
--
作者：
Uraguchi, Shimpei;Kamiya, Takehiro;Fujiwara, Toru
稻米 (Oryza sativa L.) 中镉 (Cd) 的积累会带来潜在的健康问题，尤其是在亚洲。稻米中的Cd大部分通过韧皮部转运积累，但这种转运的分子机制尚未揭示。在这项研究中，我们鉴定了一种水稻镉转运蛋白 OsLCT1，它参与镉向谷物的转运。 OsLCT1-GFP 位于植物细胞的质膜上，OsLCT1 在酵母中显示出 Cd 流出活性。在水稻植株中，在生殖阶段的叶片和节中观察到了 OsLCT1 的强表达。在最上面的节点中，在大维管束周围和弥漫性维管束中检测到 OsLCT1 转录本。 RNAi介导的OsLCT1敲低并不影响木质部介导的Cd转运，但减少了韧皮部介导的Cd转运。 OsLCT1 敲除植物在籽粒中积累的镉含量约为对照植物的一半。 OsLCT1 抑制不会对稻谷中其他金属的含量和植物生长产生负面影响。这些结果表明，OsLCT1 在镉转运到谷物的节点上发挥作用，并且在标准粳稻品种中，OsLCT1 的调节能够产生“低镉水稻”，而不会对农艺性状产生负面影响。这些发现确定了植物韧皮部镉转运的转运基因。
Accumulation of cadmium (Cd) in rice (Oryza sativa L.) grains poses a potential health problem, especially in Asia. Most Cd in rice grains accumulates through phloem transport, but the molecular mechanism of this transport has not been revealed. In this study, we identified a rice Cd transporter, OsLCT1, involved in Cd transport to the grains. OsLCT1-GFP was localized at the plasma membrane in plant cells, and OsLCT1 showed Cd efflux activity in yeast. In rice plants, strong OsLCT1 expression was observed in leaf blades and nodes during the reproductive stage. In the uppermost node, OsLCT1 transcripts were detected around large vascular bundles and in diffuse vascular bundles. RNAi-mediated knockdown of OsLCT1 did not affect xylem-mediated Cd transport but reduced phloem-mediated Cd transport. The knockdown plants of OsLCT1 accumulated approximately half as much Cd in the grains as did the control plants. The content of other metals in rice grains and plant growth were not negatively affected by OsLCT1 suppression. These results suggest that OsLCT1 functions at the nodes in Cd transport into grains and that in a standard japonica cultivar, the regulation of OsLCT1 enables the generation of "low-Cd rice" without negative effects on agronomical traits. These findings identify a transporter gene for phloem Cd transport in plants.