Integrating functional genomics and genetic mapping to clone genes responsible for low grain cadmium concentration in durum wheat

在加拿大，人类接触环境镉（Cd）的主要来源是通过受Cd污染的食物。加拿大硬粒小麦，这是超过10亿美元的价值，每年镉的积累，可能会造成不可接受的风险，镉暴露，并可能威胁到硬粒小麦的出口。已经建立了几对硬粒小麦品系，其在籽粒Cd浓度（高与低）上不同，但在其他方面遗传相似。我们以前已经表明，镉转运从根到地上部的差异可以解释这些对之一的不同颗粒镉水平。限制镉转运到地上部的机制尚未确定。我们建议联合收割机的功率转录组分析（通过比较基因表达水平，以确定感兴趣的基因）与遗传作图（以确定哪些基因的兴趣是遗传连锁的这个性状），以确定候选基因，可能参与调节镉在粮食中的积累。我们将使用酵母为基础的检测以及植物为基础的系统（病毒诱导的基因沉默），以完成候选基因的功能分析，试图确定机制（S）的基础低粮食镉。我们相信，这种方法将加快鉴定一个零距离标记的低籽粒镉，从而提供了一个快速，准确的方法来鉴定低镉育种系。这将使继续发展硬粒小麦品种的镉浓度符合国际监管标准。此外，这种标记可用于鉴定和追踪加拿大的硬粒小麦出口。鉴定硬粒小麦中低粒镉的机制可以加速其他作物中类似的发现。该项目中开发的技术和专门知识也可以扩展到其他重要的农艺性状。

The dominant source of human exposure to environmental cadmium (Cd) in Canada is through Cd-contaminated food. Accumulation of Cd in Canadian durum wheat, which is worth in excess of $1 billion a year, may pose an unacceptable risk in terms of Cd exposure and may threaten exports of durum wheat. Several pairs of durum wheat lines have been established that differ in grain Cd concentration (high vs. low), but that are otherwise genetically similar. We have previously shown that differences in Cd translocation from the roots to the shoot may explain the differing grain-Cd levels for one of these pairs. The mechanism that limits Cd translocation to the shoot has yet to be identified. We propose to combine the power of transcriptome profiling (to identify genes of interest by comparing gene expression levels) with genetic mapping (to determine which genes of interest are genetically linked to this trait) to identify candidate genes that are potentially involved in regulating Cd accumulation in grain. We will use yeast-based assays as well as a plant-based system (virus-induced gene silencing) to complete a functional analysis of the candidate genes in an attempt to identify the mechanism(s) underlying low grain-Cd. We believe that this approach will expedite the identification of a zero-distance marker for low grain-Cd, thus providing a rapid and accurate method to identify low Cd breeding lines. This will enable continued development of durum wheat varieties with Cd concentrations that meet international regulatory standards. Additionally, such a marker could be used to authenticate and trace Canada's durum wheat exports. Identification of the mechanism underlying low grain-Cd in durum wheat could accelerate similar discoveries in other crops. The techniques and expertise developed in this project could also be extended to other important agronomic traits.