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

Ling Qiao,Meng Su,Rui Wang,Jun Zheng,Kyle Isham,Jianli Chen,Weidong Zhao,Justin Wheeler,Natalie Klassen,Junli Zhang

doi:10.3389/fpls.2021.756741

Abstract

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.

Highlights

Wheat (Triticum aestivum L.) is a critically important food crop, providing 20% of the calories consumed by the population worldwide
The doubled haploid lines (DHLs) were derived from the F1 generation of a cross between two high yielding hard white spring wheat cultivars, namely, UI Platinum (UIP) and LCS Star” (LCS) Star (LCS)
UI Platinum” (UIP) flowers earlier than LCS when grown under short-day conditions

Summary

Introduction

Wheat (Triticum aestivum L.) is a critically important food crop, providing 20% of the calories consumed by the population worldwide. Due to environmental pollution and climate change, wheat faces many challenges, including biological and abiotic stress (Bowne et al, 2012; Wegulo, 2012; Guzmán et al, 2016). Heavy metal stress has attracted increased attention (Rizwan et al, 2016). Compared to other heavy metals, cadmium (Cd) is more toxic, has higher bioavailability, and is more accumulated in crops. Cd pollution is an important risk factor for the environment and human health (Shi et al, 2019).

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Results