Group of Crop Genetics and Breeding, Jiangxi Agricultural University, Nanchang 330045, China.
CAAS-IRRI Joint Laboratory for Genomics-Assisted Germplasm Enhancement, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen 518120, China.
Int J Mol Sci. 2021 Jul 30;22(15):8186. doi: 10.3390/ijms22158186.
Cadmium (Cd), a heavy metal toxic to humans, easily accumulates in rice grains. Rice with unacceptable Cd content has become a serious food safety problem in many rice production regions due to contaminations by industrialization and inappropriate waste management. The development of rice varieties with low grain Cd content is seen as an economic and long-term solution of this problem. The cation/H exchanger (CAX) family has been shown to play important roles in Cd uptake, transport and accumulation in plants. Here, we report the characterization of the rice family. The six rice genes all have homologous genes in . Phylogenetic analysis identified two subfamilies with three rice and three genes in both of them. All rice genes have trans-member structures. and were localized in the vacuolar while were localized in the plasma membrane in rice cell. The consequences of qRT-PCR analysis showed that all the six genes strongly expressed in the leaves under the different Cd treatments. Their expression in roots increased in a Cd dose-dependent manner. GUS staining assay showed that all the six rice genes strongly expressed in roots, whereas and also strongly expressed in rice leaves. The yeast () cells expressing , and grew better than those expressing the vector control on SD-Gal medium containing CdCl. and enhanced while reduced Cd accumulation in yeast. No auto-inhibition was found for all the rice genes. Therefore, , and are likely to involve in Cd uptake and translocation in rice, which need to be further validated.
镉（Cd）是一种对人体有毒的重金属，很容易在稻米中积累。由于工业化和废物管理不当造成的污染，稻米中 Cd 含量过高已成为许多稻米产区的一个严重食品安全问题。开发低粮 Cd 含量的稻米品种被视为解决这一问题的经济和长期方案。阳离子/H 交换器（CAX）家族已被证明在植物 Cd 吸收、转运和积累中发挥重要作用。本研究报道了水稻 家族的特征。这 6 个水稻 基因在 中都有同源基因。系统发育分析确定了两个亚家族，其中有 3 个水稻基因和 3 个 基因。所有水稻 基因都具有跨膜结构。在水稻细胞中， 与 定位于液泡， 定位于质膜。定量 RT-PCR 分析的结果表明，在不同 Cd 处理下，所有 6 个基因在叶片中均强烈表达。在根系中，它们的表达随 Cd 剂量的增加呈剂量依赖性增加。GUS 染色分析表明，所有 6 个水稻 基因在根系中强烈表达，而 与 也在水稻叶片中强烈表达。表达 、 和 的酵母（）细胞在含有 CdCl 的 SD-Gal 培养基上比表达载体对照的酵母细胞生长得更好。 与 增强了酵母细胞对 Cd 的积累，而 则降低了 Cd 的积累。所有水稻 基因均未发现自身抑制现象。因此， 、 与 可能参与了水稻对 Cd 的摄取和转运，需要进一步验证。
