Data_Sheet_2_Novel Quantitative Trait Loci for Grain Cadmium Content Identified in Hard White Spring Wheat.xlsx

Cadmium (Cd) is a heavy metal that can cause a variety of adverse effects on human health, including cancer. Wheat comprises approximately 20% of the human diet worldwide; therefore, reducing the concentrations of Cd in wheat grain will have significant impacts on the intake of Cd in food products. The tests for measuring the Cd content in grain are costly, and the content is affected significantly by soil pH. To facilitate breeding for low Cd content, this study sought to identify quantitative trait loci (QTL) and associated molecular markers that can be used in molecular breeding. One spring wheat population of 181 doubled haploid lines (DHLs), which was derived from a cross between two hard white spring wheat cultivars “UI Platinum” (UIP) and “LCS Star” (LCS), was assessed for the Cd content in grain in multiple field trials in Southeast Idaho, United States. Three major QTL regions, namely, QCd.uia2-5B, QCd.uia2-7B, and QCd.uia2-7D, were identified on chromosomes 5B, 7B, and 7D, respectively. All genes in these three QTL regions were identified from the NCBI database. However, three genes related to the uptake and transport of Cd were used in the candidate gene analysis. The sequences of TraesCS5B02G388000 (TaHMA3) in the QCd.uia2-5B region and TraesCS7B02G320900 (TaHMA2) and TraesCS7B02G322900 (TaMSRMK3) in the QCd.uia2-7B region were compared between UIP and LCS. TaHMA2 on 7B is proposed for the first time as a candidate gene for grain Cd content in wheat. A KASP marker associated with this gene was developed and it will be further validated in near-isogenic lines via a gene-editing system in future studies.

镉（Cadmium, Cd）是一种可对人体健康造成多种不良影响（包括诱发癌症）的重金属。小麦在全球人类饮食中占比约20%，因此降低小麦籽粒中的镉浓度，将对食品中的镉摄入量产生显著影响。当前籽粒镉含量的检测成本高昂，且该含量受土壤pH值影响显著。为助力低镉含量小麦的育种工作，本研究旨在鉴定可用于分子育种的数量性状位点（quantitative trait loci, QTL）及相关分子标记。本研究以两个硬白春小麦品种"UI Platinum"（UIP）与"LCS Star"（LCS）杂交得到的181份双单倍体群体（doubled haploid lines, DHLs）为材料，在美国爱达荷州东南部的多个田间试验中测定了其籽粒的镉含量。研究分别在5B、7B和7D染色体上鉴定到3个主效QTL区域，即QCd.uia2-5B、QCd.uia2-7B和QCd.uia2-7D。研究人员从美国国家生物技术信息中心（NCBI）数据库中获取了这3个QTL区域内的全部基因，但仅选取3个与镉吸收和转运相关的基因开展候选基因分析：对QCd.uia2-5B区域内的TraesCS5B02G388000（TaHMA3），以及QCd.uia2-7B区域内的TraesCS7B02G320900（TaHMA2）和TraesCS7B02G322900（TaMSRMK3）的序列，在UIP与LCS两个品种间进行了比对。本研究首次将7B染色体上的TaHMA2提出作为小麦籽粒镉含量相关的候选基因。研究人员开发了与该基因关联的KASP标记，并计划在未来研究中通过基因编辑系统在近等基因系中对该标记进行进一步验证。