The cuticle is the plant's barrier against abiotic and biotic stresses, and the deposition of epicuticular wax crystals results in the scattering of light, an effect termed glaucousness. Here, we dissect the genetic architecture of flag leaf glaucousness in wheat toward a future targeted design of the cuticle. The cuticle serves as a barrier that protects plants against abiotic and biotic stresses. Differences in cuticle composition can be detected by the scattering of light on epicuticular wax crystals, which causes a phenotype termed glaucousness. In this study, we dissected the genetic architecture of flag leaf glaucousness in a panel of 1106 wheat cultivars of global origin. We observed a large genotypic variation, but the geographic pattern suggests that other wax layer characteristics besides glaucousness may be important in conferring tolerance to abiotic stresses such as heat and drought. Genome-wide association mapping identified two major quantitative trait loci (QTL) on chromosomes 3A and 2B. The latter corresponds to the W1 locus, but further characterization revealed that it is likely to contain additional QTL. The same holds true for the major QTL on 3A, which was also found to show an epistatic interaction with another locus located a few centiMorgan distal to it. Genome-wide prediction and the identification of a few additional putative QTL revealed that small-effect QTL also contribute to the trait. Collectively, our results illustrate the complexity of the genetic control of flag leaf glaucousness, with additive effects and epistasis, and lay the foundation for the cloning of the underlying genes toward a more targeted design of the cuticle by plant breeding.

中文翻译：

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改进小麦旗叶青光的遗传结构。

角质层是植物抵御非生物和生物胁迫的屏障，角质层蜡晶体的沉积导致光的散射，这种效应称为白光。在这里，我们剖析了小麦中旗叶青光的遗传结构，以期未来有针对性地设计角质层。角质层充当保护植物免受非生物和生物胁迫的屏障。角质层成分的差异可以通过光在角质层蜡晶体上的散射来检测，这会导致称为白浊的表型。在这项研究中，我们在一组 1106 个全球小麦品种中剖析了旗叶白斑的遗传结构。我们观察到很大的基因型变异，但地理模式表明，除白霜外，其他蜡层特征可能对赋予对非生物胁迫（如热和干旱）的耐受性很重要。全基因组关联作图确定了染色体 3A 和 2B 上的两个主要数量性状基因座 (QTL)。后者对应于 W1 基因座，但进一步的表征表明它可能包含额外的 QTL。3A 上的主要 QTL 也是如此，它也被发现与位于其远端几厘摩根的另一个基因座显示上位相互作用。全基因组预测和一些额外推定 QTL 的鉴定表明，小效应 QTL 也有助于该性状。总的来说，我们的结果说明了旗叶青光遗传控制的复杂性，具有加性效应和上位性，