Although WRKY transcription factors (TFs) are known to be involved in the regulation of plant root development, the mechanisms by which these TFs regulate plant tolerance to ammonium (NH₄⁺) toxicity remain unclear. To identify the molecular mechanisms underlying NH₄⁺-induced repression of primary root growth and NH₄⁺ sensitivity in Arabidopsis, wild-type (Col-0) and mutant (wrky23) plants were treated with 10 mM KNO₃ (control) or 5 mM (NH₄)₂SO₄ (NH₄⁺ toxicity) for 7 days. Under NH₄⁺ toxicity, the fresh weight of wrky23 mutant was significantly lower than that of Col-0 plants, and the NH₄⁺ concentration in wrky23 roots was significantly higher than that in Col-0 roots. However, we observed no significant differences between the two genotypes under the control treatment. Ammonium transporter AMT1;2 expression was induced in wrky23 roots but not in Col-0 roots. The transcript levels of cytosolic glutamine synthetase-encoding genes and activity of glutamine synthetase did not differ significantly between wrky23 and Col-0. Furthermore, the fluorescence and staining patterns of DR5::GFP and DR5::GUS, respectively, were more pronounced under NH₄⁺ toxicity than under the control treatment. Collectively, our results indicate that AMT1;2 expression was induced in the wrky23 mutant in response to NH₄⁺ toxicity, leading to NH₄⁺ accumulation in the roots and primary root growth repression. Under NH₄⁺ toxicity, both auxin transport and distribution were affected, and auxin accumulation in the root tips inhibited primary root growth in the wrky23 mutant. Our study provides important insights into the molecular mechanisms by which WRKY23 TF regulates plant responses to NH₄⁺ toxicity.

尽管已知WRKY转录因子（TFs）参与植物根系发育的调控，但这些TF调控植物对铵（NH ₄ ⁺）毒性的耐受性的机制仍不清楚。为了确定拟南芥中NH ₄ ⁺诱导的初级根生长抑制和NH ₄ ⁺敏感性抑制的分子机制，将野生型（Col-0）和突变型（wrky23）植物用10 mM KNO ₃（对照）或5处理。 mM（NH ₄）₂ SO ₄（NH ₄ ⁺毒性）7天。在NH ₄ ^+下毒性，wrky23突变体的鲜重明显低于Col-0植物，而wrky23根中的NH ₄ ⁺浓度明显高于Col-0根。然而，我们观察到在对照处理下两种基因型之间没有显着差异。铵转运蛋白AMT1; 2表达在wrky23根中诱导，但在Col-0根中未诱导。在wrky23和Col-0之间，胞质谷氨酰胺合成酶编码基因的转录水平和谷氨酰胺合成酶的活性没有显着差异。此外，DR5 :: GFP和DR5 :: GUS的荧光和染色模式分别在NH ₄ ⁺毒性下比在对照处理下更明显。总体而言，我们的结果表明，在wrky23突变体中，NHT ₄ ⁺毒性反应诱导了AMT1; 2的表达，导致NH ₄ ⁺在根中的积累和根系的初级生长抑制。在NH ₄ ⁺毒性作用下，生长素的运输和分布都受到影响，并且生长素在根尖的积累抑制了wrky23突变体的初级根生长。我们的研究为WRKY23 TF调节植物对NH ₄ ^+的反应的分子机制提供了重要的见识。 毒性。