Table_3_Phenotypic Evaluation and Genetic Analysis of Seedling Emergence in a Global Collection of Wheat Genotypes (Triticum aestivum L.) Under Limited Water Availability.XLSX

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，播种于深层土壤水分（>10厘米）或干燥表层土壤（4厘米）时，需保证幼苗的一致性高率出土。然而，后者高度依赖于最低土壤水分的可用性，以确保幼苗成功出土。本研究旨在：（1）评估233个澳大利亚及精选的国际小麦基因型在土壤水分有限的情况下，在田间和温室（GH）试验中播种于4厘米表层土壤时，能否保持幼苗高率出土；（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）比较不同位点控制茎鞘特征、发芽、休眠和收获前萌发等性状。尽管田间和温室试验中存在显著的（P < 0.001）环境和基因型与环境相互作用，但包括五个品种、两个地方种和一种自交系的八个基因型在九个环境中均表现出一致的幼苗高率出土（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，并确定了与茎鞘长度、宽度、横截面积，收获前萌发和休眠，发芽，种子寿命和花青素发育连锁的16个幼苗出土QTL。因此，幼苗出土似乎受到由相互关联的基因和性状组成的多元网络调控，这些基因和性状受不同环境信号调节。