Genome‐wide association mapping identifies quantitative trait loci (QTL) that influence the mean differences between the marker genotypes for a given trait. While most loci influence the mean value of a trait, certain loci, known as variance heterogeneity QTL (vQTL) determine the variability of the trait instead of the mean trait value (mQTL). In the present study, we performed a variance heterogeneity genome‐wide association study (vGWAS) for grain cadmium (Cd) concentration in bread wheat. We used double generalized linear model and hierarchical generalized linear model to identify vQTL associated with grain Cd. We identified novel vQTL regions on chromosomes 2A and 2B that contribute to the Cd variation and loci that affect both mean and variance heterogeneity (mvQTL) on chromosome 5A. In addition, our results demonstrated the presence of epistatic interactions between vQTL and mvQTL, which could explain variance heterogeneity. Overall, we provide novel insights into the genetic architecture of grain Cd concentration and report the first application of vGWAS in wheat. Moreover, our findings indicated that epistasis is an important mechanism underlying natural variation for grain Cd concentration.

中文翻译：

---

面包小麦中镉的方差异质性全基因组图谱揭示了新的基因组位点和上位相互作用

全基因组关联图谱鉴定了定量性状位点（QTL），其影响给定性状的标记基因型之间的平均差异。尽管大多数基因座会影响性状的平均值，但某些基因座（称为方差异质性QTL（vQTL））会决定性状的变异性，而不是平均性状值（mQTL）。在本研究中，我们对面包小麦中的镉（Cd）浓度进行了方差异质性全基因组关联研究（vGWAS）。我们使用双重广义线性模型和层次广义线性模型来识别与晶粒Cd相关的vQTL。我们在染色体2A和2B上鉴定了新的vQTL区域，这些区域会影响Cd变异和基因座，从而影响5A染色体上的均值和方差异质性（mvQTL）。此外，我们的结果证明了vQTL和mvQTL之间存在上位相互作用，这可以解释方差异质性。总体而言，我们提供了关于谷物Cd浓度遗传结构的新颖见解，并报告了vGWAS在小麦中的首次应用。此外，我们的发现表明上位性是谷物Cd浓度自然变化的重要机制。