Table_2_Phenotypic Evaluation and Genetic Analysis of Seedling Emergence in a Global Collection of Wheat Genotypes (Triticum aestivum L.) Under Limited Water Availability.DOCX

The challenge in establishing an early-sown wheat crop in southern Australia is the need for consistently high seedling emergence when sowing deep in subsoil moisture (>10 cm) or into dry top-soil (4 cm). However, the latter is strongly reliant on a minimum soil water availability to ensure successful seedling emergence. This study aimed to: (1) evaluate 233 Australian and selected international wheat genotypes for consistently high seedling emergence under limited soil water availability when sown in 4 cm of top-soil in field and glasshouse (GH) studies; (2) ascertain genetic loci associated with phenotypic variation using a genome-wide association study (GWAS); and (3) compare across loci for traits controlling coleoptile characteristics, germination, dormancy, and pre-harvest sprouting. Despite significant (P < 0.001) environment and genotype-by-environment interactions within and between field and GH experiments, eight genotypes that included five cultivars, two landraces, and one inbred line had consistently high seedling emergence (mean value > 85%) across nine environments. Moreover, 21 environment-specific quantitative trait loci (QTL) were detected in GWAS analysis on chromosomes 1B, 1D, 2B, 3A, 3B, 4A, 4B, 5B, 5D, and 7D, indicating complex genetic inheritance controlling seedling emergence. We aligned QTL for known traits and individual genes onto the reference genome of wheat and identified 16 QTL for seedling emergence in linkage disequilibrium with coleoptile length, width, and cross-sectional area, pre-harvest sprouting and dormancy, germination, seed longevity, and anthocyanin development. Therefore, it appears that seedling emergence is controlled by multifaceted networks of interrelated genes and traits regulated by different environmental cues.

在澳大利亚南部建立早播小麦作物所面临的挑战在于，在深层土壤水分（>10厘米）或干燥表层土壤（4厘米）中播种时，需要保持一致的幼苗出土率。然而，后者强烈依赖于土壤水分的最低可用量，以确保幼苗成功出土。本研究旨在：（1）评估在田间和温室（GH）研究中，在4厘米表层土壤中播种时，233个澳大利亚和选定的国际小麦基因型在有限土壤水分条件下的一致性高幼苗出土率；（2）利用全基因组关联研究（GWAS）确定与表型变异相关的遗传位点；（3）比较控制鞘翅特征、发芽、休眠和收获前萌发的性状在不同位点上的表现。尽管在田间和温室实验中以及它们之间存在显著的（P < 0.001）环境和基因型与环境交互作用，但包括五个品种、两个地方品种和一个自交系在内的八个基因型在九个环境中均表现出一致的高幼苗出土率（平均值>85%）。此外，在1B、1D、2B、3A、3B、4A、4B、5B、5D和7D染色体上检测到21个环境特异性数量性状位点（QTL），表明控制幼苗出土率的遗传遗传机制复杂。我们将已知性状和单个基因的QTL与小麦参考基因组对齐，并确定了16个与鞘翅长度、宽度和横截面积、收获前萌发和休眠、发芽、种子寿命和花青素发育相关的QTL。因此，似乎幼苗出土率受多方面相互关联的基因和性状网络控制，这些基因和性状受到不同环境信号的调节。