Drought stress occurred at early growth stages in wheat affecting the following growth stages. Therefore, selecting promising drought-tolerant genotypes with highly adapted traits at the seedling stage is an important task for wheat breeders and geneticists. Few research efforts were conducted on genetic control for drought-adaptive traits at the seedling stage in wheat. In this study, a set of 146 highly diverse spring wheat core collections representing 28 different countries was evaluated under drought stress at the seedling stage. All genotypes were exposed to drought stress for 13 days by water withholding. Leaf traits including seedling length, leaf wilting, days to wilting, leaf area, and leaf rolling were scored. Moreover, root traits such as root length, maximum width, emergence angle, tip angle, and number of roots were scored. Considerable significant genetic variation was found among all genotypes tested in these experiments. The heritability estimates ranged from 0.74 (leaf witling) to 0.99 (root tip angle). A set of nine genotypes were selected and considered drought-tolerant genotypes. Among all leaf traits, shoot length had significant correlations with all root traits under drought stress. The 146 genotypes were genotyped using the Infinium Wheat 15K single nucleotide polymorphism (SNP) array and diversity arrays technology (DArT) marker platform. The result of genotyping revealed 12,999 SNPs and 2,150 DArT markers which were used to run a genome-wide association study (GWAS). The results of GWAS revealed 169 markers associated with leaf and root traits under drought stress. Out of the 169 markers, 82 were considered major QTLs. The GWAS revealed 95 candidate genes were identified with 53 genes showing evidence for drought tolerance in wheat, while the remaining candidate genes were considered novel. No shared markers were found between leaf and root traits. The results of the study provided mapping novel markers associated with new root traits at the seedling stage. Also, the selected genotypes from different countries could used in future wheat breeding programs not only for improving adaptive drought-tolerant traits but also for expanding genetic diversity.

中文翻译：

---

在高度生态多样化的小麦群体中，对与苗期耐旱性相关的根和叶结构性状进行全基因组分析

干旱胁迫发生在小麦的早期生长阶段，影响随后的生长阶段。因此，在苗期选择具有高度适应性状的有前景的耐旱基因型是小麦育种家和遗传学家的一项重要任务。关于小麦苗期干旱适应性状遗传控制的研究很少。在这项研究中，对来自 28 个不同国家的 146 个高度多样化的春小麦核心种质进行了幼苗期干旱胁迫下的评估。所有基因型均通过停水暴露于干旱胁迫13天。对叶子性状进行评分，包括幼苗长度、叶子枯萎、枯萎天数、叶面积和叶子卷曲。此外，还对根长、最大宽度、出苗角度、尖端角度和根数等根性状进行评分。在这些实验中测试的所有基因型中发现了相当大的显着遗传变异。遗传力估计范围为 0.74（叶枯萎）至 0.99（根尖角）。选择了一组九个基因型并被认为是耐旱基因型。在所有叶片性状中，干旱胁迫下芽长与所有根性状均显着相关。使用 Infinium Wheat 15K 单核苷酸多态性 (SNP) 阵列和多样性阵列技术 (DArT) 标记平台对 146 种基因型进行基因分型。基因分型结果显示了 12,999 个 SNP 和 2,150 个 DArT 标记，这些标记用于运行全基因组关联研究 (GWAS)。GWAS 结果揭示了 169 个与干旱胁迫下叶和根性状相关的标记。在 169 个标记中，82 个被认为是主要 QTL。GWAS 揭示了 95 个候选基因，其中 53 个基因显示了小麦耐旱性的证据，而其余候选基因被认为是新的。叶和根性状之间没有发现共享标记。该研究的结果提供了与苗期新根性状相关的新标记的绘制。此外，来自不同国家的选定基因型可以用于未来的小麦育种计划，不仅可以提高适应性耐旱性状，还可以扩大遗传多样性。