National Key Laboratory of Crop Genetic Improvement and College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070, China.
Planta. 2018 May;247(5):1247-1260. doi: 10.1007/s00425-018-2859-0. Epub 2018 Feb 7.
Heterogeneous expression of the rice genes "fruit-weight 2.2-like" (OsFWL) affects Cd resistance in yeast, and OsFWL4 mediates the translocation of Cd from roots to shoots. Cadmium (Cd) induces chronic and toxic effects in humans. In a previous study (Xu et al. in Planta 238:643-655, 2013), we cloned the rice genes, designated OsFWL1-8, homologous to the tomato fruit-weight 2.2. Here, we show that expression of genes OsFWL3-7 in yeast confers resistance to Cd. The Cd contents of OsFWL3-, -4-, -6- and -7-transformed Cd(II)-sensitive yeast mutant ycf1 cells were strongly decreased compared with those of empty vector, with the strongest resistance to Cd observed in cells expressing OsFWL4. Evaluation of truncated and site-directed mutation derivatives revealed that the CCXXG motifs near the second transmembrane region of OsFWL4 are involved in Cd resistance in yeast. Real-time PCR analysis showed that OsFWL4 expression was induced by CdCl stress in rice seedlings. Compared with WT plants, the Cd contents in the shoots of RNAi mediated OsFWL4 knockdown plants were significantly decreased, and Cd translocation from roots to shoots was reduced. According to bimolecular fluorescence complementation, yeast two-hybrid and Western-blotting assays, the OsFWL4 protein forms homo-oligomers. These results suggest that OsFWL4 might act directly as a transporter and is involved in the translocation of Cd from roots to shoots in rice.
水稻基因“果实重量 2.2 样”（OsFWL）的异源表达影响酵母对 Cd 的抗性，而 OsFWL4 介导 Cd 从根部向地上部的转运。Cd 对人体有慢性和毒性作用。在之前的一项研究中（Xu 等人在《植物》238:643-655, 2013 年），我们克隆了水稻基因，命名为 OsFWL1-8，与番茄果实重量 2.2 同源。在这里，我们表明，酵母中 OsFWL3-7 基因的表达赋予了对 Cd 的抗性。与空载体相比，OsFWL3-、-4-、-6-和-7 转化的 Cd(II)敏感酵母突变体 ycf1 细胞中的 Cd 含量强烈降低，其中 OsFWL4 表达的细胞对 Cd 的抗性最强。截短和定点突变衍生物的评估表明，OsFWL4 近第二跨膜区域的 CCXXG 基序参与酵母中的 Cd 抗性。实时 PCR 分析表明，OsFWL4 表达受 CdCl 胁迫在水稻幼苗中诱导。与 WT 植物相比，RNAi 介导的 OsFWL4 敲低植物地上部分的 Cd 含量显著降低，Cd 从根部向地上部的转运减少。根据双分子荧光互补、酵母双杂交和 Western-blotting 分析，OsFWL4 蛋白形成同源寡聚体。这些结果表明，OsFWL4 可能直接作为转运体发挥作用，参与水稻中 Cd 从根部向地上部的转运。
