Seed germination, one of the most important stages in a plant’s life cycle, can be affected by abiotic stresses, such as salinity. The plant hormone abscisic acid (ABA) and high concentrations of glucose are also known to inhibit germination. In contrast, nitrate is known to stimulate germination in many plants. However, this stimulatory effect has not yet been investigated in the presence of inhibitory effects caused by abiotic stresses, ABA, and glucose. In this study, we show that nitrate can alleviate the inhibitory effects of sodium chloride (NaCl) or high concentrations of glucose on seed germination in Arabidopsis, while it was not able to promote germination that was inhibited by exogenous ABA and mannitol (an inducer of osmotic stress). An analysis of the gene expression involved in the regulation of germination showed that GA20ox1, encoding the gibberellin (GA) synthesis enzyme, SPATULA (SPT), encoding a bHLH transcription factor, and CYP707A2, encoding an ABA catabolic enzyme, were significantly upregulated by the addition of KNO₃ in the presence of NaCl or glucose. Our results suggest the possibility that these genes are involved in the nitrate-mediated control of seed germination in the presence of NaCl or glucose.

中文翻译：

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硝酸盐在NaCl抑制或高浓度葡萄糖的作用下促进发芽。

种子发芽是植物生命周期中最重要的阶段之一，它会受到非生物胁迫（例如盐度）的影响。还已知植物激素脱落酸（ABA）和高浓度的葡萄糖会抑制发芽。相反，已知硝酸盐可刺激许多植物发芽。但是，在存在由非生物胁迫，ABA和葡萄糖引起的抑制作用的情况下，尚未研究这种刺激作用。在这项研究中，我们表明硝酸盐可以减轻氯化钠（NaCl）或高浓度的葡萄糖对拟南芥种子萌发的抑制作用。，但是它不能促进被外源ABA和甘露醇（渗透压的诱导剂）抑制的发芽。对参与萌发调节的基因表达的分析表明，编码赤霉素（GA）合成酶的GA20ox1，编码bHLH转录因子的SPATULA（SPT）和编码ABA分解代谢酶的CYP707A2被上调了。在NaCl或葡萄糖存在下添加KNO ₃。我们的结果表明，在NaCl或葡萄糖存在下，这些基因可能参与硝酸盐介导的种子萌发控制。