ZmHMA3, a Member of the Heavy-Metal-Transporting ATPase Family, Regulates Cd and Zn Tolerance in Maize

Abstract

The pollution of heavy metals is extremely serious in China, including zinc (Zn), copper (Cu), lead (Pb), and cadmium (Cd). Heavy-metal-transporting ATPase (HMA) belongs to a subfamily of the P-ATPase family, which absorbs and transports Zn, Cu, Pb, and Cd in plants. Here, we describe a <i>ZmHMA</i>-encoding HMA family protein that positively regulates Cd and Zn tolerance. The real-time fluorescence quantification (RT-PCR) results revealed that <i>ZmHMA3</i> had a high expression in B73, and the expression of <i>ZmHMA3</i> was sensitive to Cd in yeast cells, which was related to Cd accumulation in yeast. Additionally, the <i>Arabidopsis thaliana</i> homologous mutants of <i>AtHMA2</i> showed Cd sensitivity compared with WT. The overexpressing <i>ZmHMA3</i> plants showed higher tolerance under Cd and Zn stresses than the wild type. The overexpression of <i>ZmHMA3</i> led to higher Cd and Zn accumulation in tissues based on the subcellular distribution analysis. We propose that <i>ZmHMA3</i> improves maize tolerance to Cd and Zn stresses by absorbing and transporting Cd and Zn ions. This study elucidates the gene function of the <i>ZmHMA3</i> response to Cd and Zn stress and provides a reference for improving the characteristics of heavy metals enrichment in existing maize varieties and the plant remediation technology of heavy-metal-contaminated soil.