Maize Research Institute, Sichuan Agricultural University, Chengdu, 611130, China.
Department of Agronomy, Purdue University, West Lafayette, 47906, USA.
BMC Genomics. 2018 Jan 25;19(1):91. doi: 10.1186/s12864-017-4395-x.
Accumulation of cadmium (Cd) in maize (Zea mays L.) poses a significant risk to human health as it is ingested via the food chain. A genome-wide association study (GWAS) was conducted in a population of 269 maize accessions with 43,737 single nucleotide polymorphisms (SNPs) to identify candidate genes and favorable alleles for controlling Cd accumulation in maize.
When grown in contaminated soil, accessions varied significantly in leaf Cd concentration at both the seeding and maturing stages with phenotypic variation and the coefficient of variation all above 48%. The co-localized region between SYN27837 (147,034,650 bp) and SYN36598 (168,551,327 bp) on chromosome 2 was associated with leaf Cd under three soil conditions varying in Cd content in 2015 and 2016. The significant SNP (SYN25051) at position 161,275,547 could explained 27.1% of the phenotype variation. Through QTL mapping using the IBMSyn10 double haploid (DH) population, we validated the existence of a major QTL identified by GWAS; qLCd2 could explain the 39.8% average phenotype variation across the experiments. Expression of GRMZM2G175576 encoding a cadmium/zinc-transporting ATPase underlying the QTL was significantly increased in roots, stems and leaves of B73, a low Cd accumulation line in response to Cd stress.
Our findings provide new insights into the genetic control of Cd accumulation and could aid rapid development of maize genotypes with low-Cd accumulation by manipulation of the favorable alleles.
玉米（Zea mays L.）中镉（Cd）的积累对人类健康构成重大风险，因为它通过食物链被摄入。对 269 个玉米品种进行了全基因组关联研究（GWAS），使用 43737 个单核苷酸多态性（SNP）来鉴定候选基因和控制玉米中 Cd 积累的有利等位基因。
在污染土壤中生长时，品种在种子期和成熟期的叶片 Cd 浓度差异显著，表型变异和变异系数均高于 48%。2015 年和 2016 年，在 Cd 含量不同的三种土壤条件下，SYN27837（147034650 bp）和 SYN36598（168551327 bp）之间的共定位区域与叶片 Cd 有关。位于 161275547 位的显著 SNP（SYN25051）可以解释 27.1%的表型变异。通过使用 IBMSyn10 双单倍体（DH）群体进行 QTL 作图，我们验证了 GWAS 鉴定的一个主要 QTL 的存在；qLCd2 可以解释实验中 39.8%的平均表型变异。在对 Cd 胁迫的低 Cd 积累系 B73 中，该 QTL 下编码 Cd/Zn 转运 ATP 酶的 GRMZM2G175576 基因的表达在根、茎和叶中显著增加。
我们的研究结果为 Cd 积累的遗传控制提供了新的见解，并通过对有利等位基因的操纵，有助于快速开发低 Cd 积累的玉米基因型。
