Natural variations in the P-type ATPase heavy metal transporter gene ZmHMA3 control cadmium accumulation in maize grains

• Published in: Journal of experimental botany Vol. 72; no. 18; pp. 6230 - 6246
• Main Authors: Tang, Bin, Luo, Meijie, Zhang, Yunxia, Guo, Huanle, Li, Jingna, Song, Wei, Zhang, Ruyang, Feng, Zhen, Kong, Mengsi, Li, Han, Cao, Zhongyang, Lu, Xiaoduo, Li, Delin, Zhang, Jianhua, Wang, Ronghuan, Wang, Yuandong, Chen, Zhihui, Zhao, Yanxin, Zhao, Jiuran
• Format: Journal Article
• Language: English
• Published: UK Oxford University Press 30.09.2021
• Subjects: haplotype; grain; maize; molecular markers; Cadmium accumulation
• ISSN: 0022-0957; 1460-2431; 1460-2431
• DOI: 10.1093/jxb/erab254

Abstract Cadmium (Cd) accumulation in maize grains is detrimental to human health. Developing maize varieties with low Cd content is important for safe consumption of maize grains. However, the key genes controlling maize grain Cd accumulation have not been cloned. Here, we identified one major locus for maize grain Cd accumulation (qCd1) using a genome-wide association study (GWAS) and bulked segregant RNA-seq analysis with a biparental segregating population of Jing724 (low-Cd line) and Mo17 (high-Cd line). The candidate gene ZmHMA3 was identified by fine mapping and encodes a tonoplast-localized heavy metal P-type ATPase transporter. An ethyl methane sulfonate mutant analysis and an allelism test confirmed that ZmHMA3 influences maize grain Cd accumulation. A transposon in intron 1 of ZmHMA3 is responsible for the abnormal amino acid sequence in Mo17. Based on the natural sequence variations in the ZmHMA3 gene of diverse maize lines, four PCR-based molecular markers were developed, and these were successfully used to distinguish five haplotypes with different grain Cd contents in the GWAS panel and to predict grain Cd contents of widely used maize inbred lines and hybrids. These molecular markers can be used to breed elite maize varieties with low grain Cd contents. The heavy metal ATPase transporter ZmHMA3 controls maize grain Cd accumulation. Novel molecular markers were developed that serve as genotyping tools to predict Cd accumulation in maize.