Farquharson Lochlen G H, Samanfar Bahram, Khanal Raja, Brauer Elizabeth K
Ottawa Research and Development Centre, Agriculture and Agri-Food Canada, Ottawa, Ontario, Canada.
Department of Biology, University of Ottawa, Ottawa, Ontario, Canada.
Plant Genome. 2025 Jun;18(2):e70063. doi: 10.1002/tpg2.70063.
Seed dormancy is regulated by a combination of developmental and environmental cues to ensure seedling survival in a changing environment. In barley (Hordeum vulgare L.), the SD1 and SD2 (where SD is standard deviation) loci regulate dormancy and pre-harvest sprouting (PHS), though their role in physiological development remains unclear. Malting barley production in Eastern Canada is currently limited due to the high potential for PHS in the region. To understand what genetic loci might be influencing dormancy in Eastern Canadian barley, we evaluated the LegCi biparental population, which was derived from the Léger variety. A quantitative trait loci close to the SD1 on chromosome 5 locus was identified as regulating germination in LegCi, suggesting that the alanine aminotransferase gene (AlaAT1), which underlies dormancy regulation at SD1, influences dormancy in LegCi. Alanine aminotransferases influence energy production in the cell, particularly during nitrogen limitation or oxygen deprivation. LegCi genotypes segregating for dormancy at the SD1 allele showed no differences in abscisic acid or GA-dependent gene expression during grain fill but varied for hypoxia-induced gene expression. Hypoxia suppressed germination in all genotypes but had a significantly higher impact on genotypes with the dormant AlaAT1 relative to genotypes with the non-dormant AlaAT1. This trend was not dependent on the presence of the hull, suggesting that signaling or metabolism inside the germinating seed is influencing hypoxia sensitivity. This work suggests that the non-dormant allele of SD1 is associated with reduced hypoxia stress sensitivity to promote germination. Further work is needed to determine if this trend extends to other barley genotypes.
种子休眠受发育和环境线索的综合调控，以确保幼苗在不断变化的环境中存活。在大麦（Hordeum vulgare L.）中，SD1和SD2（SD为标准差）位点调控休眠和收获前发芽（PHS），但其在生理发育中的作用仍不清楚。由于该地区PHS发生的可能性很高，加拿大东部的麦芽大麦生产目前受到限制。为了了解哪些基因位点可能影响加拿大东部大麦的休眠，我们评估了源自Léger品种的LegCi双亲群体。在LegCi群体中，一个位于5号染色体上靠近SD1的数量性状位点被确定为调控发芽，这表明在SD1位点上调控休眠的丙氨酸转氨酶基因（AlaAT1）影响了LegCi的休眠。丙氨酸转氨酶影响细胞内的能量产生，特别是在氮限制或缺氧期间。在SD1等位基因上因休眠而分离的LegCi基因型在灌浆期间脱落酸或赤霉素依赖基因的表达上没有差异，但在缺氧诱导基因的表达上有所不同。缺氧抑制了所有基因型的发芽，但相对于具有非休眠AlaAT1的基因型，对具有休眠AlaAT1的基因型的影响显著更大。这种趋势不依赖于颖壳的存在，这表明发芽种子内部的信号传导或代谢正在影响缺氧敏感性。这项研究表明，SD1的非休眠等位基因与降低缺氧胁迫敏感性以促进发芽有关。需要进一步的研究来确定这种趋势是否适用于其他大麦基因型。
