Department of Biological Production, Faculty of Bioresource Sciences, Akita Prefectural University, Shimoshinjyo-Nakano, Akita, Japan.
Plant Cell Physiol. 2012 Jan;53(1):213-24. doi: 10.1093/pcp/pcr166. Epub 2011 Nov 28.
Widespread soil contamination with heavy metals has fostered the need for plant breeders to develop new crops that do not accumulate heavy metals. Metal-transporting transmembrane proteins that transport heavy metals across the plant plasma membrane are key targets for developing these new crops. Oryza sativa heavy metal ATPase 3 (OsHMA3) is known to be a useful gene for limiting cadmium (Cd) accumulation in rice. OsHMA2 is a close homolog of OsHMA3, but the function of OsHMA2 is unknown. To gain insight into the function of OsHMA2, we analyzed three Tos17 insertion mutants. The translocation ratios of zinc (Zn) and Cd were clearly lower in all mutants than in the wild type, suggesting that OsHMA2 is a major transporter of Zn and Cd from roots to shoots. By comparing each allele in the OsHMA2 protein structure and measuring the Cd translocation ratio, we identified the C-terminal region as essential for Cd translocation into shoots. Two alleles were identified as good material for breeding rice that does not contain Cd in the grain but does contain some Zn, and that grows normally.
土壤中重金属的广泛污染促使植物育种家开发新的作物品种，这些品种不会积累重金属。将重金属穿过植物质膜运输的金属转运跨膜蛋白是开发这些新作物的关键目标。水稻重金属 ATP 酶 3（OsHMA3）是一种限制水稻中镉（Cd）积累的有用基因。OsHMA2 是 OsHMA3 的紧密同源物，但 OsHMA2 的功能未知。为了深入了解 OsHMA2 的功能，我们分析了三个 Tos17 插入突变体。所有突变体中锌（Zn）和 Cd 的转运比率明显低于野生型，这表明 OsHMA2 是 Zn 和 Cd 从根部向地上部运输的主要转运蛋白。通过比较 OsHMA2 蛋白结构中的每个等位基因，并测量 Cd 的转运比率，我们确定 C 末端区域对于 Cd 向地上部的转运是必需的。通过比较 OsHMA2 蛋白结构中的每个等位基因，并测量 Cd 的转运比率，我们确定 C 末端区域对于 Cd 向地上部的转运是必需的。通过比较 OsHMA2 蛋白结构中的每个等位基因，并测量 Cd 的转运比率，我们确定 C 末端区域对于 Cd 向地上部的转运是必需的。两个等位基因被确定为培育不含有 Cd 但含有一定量 Zn 的正常生长水稻的良好材料。
