Schenk Sebastian T, Brehaut Virginie, Chardin Camille, Boudsocq Marie, Marmagne Anne, Colcombet Jean, Krapp Anne
Université Paris-Saclay, CNRS, INRAE, Institute of Plant Sciences Paris-Saclay (IPS2), 91190, Gif sur Yvette, France.
Université Paris-Saclay, INRAE, AgroParisTech, Institut Jean-Pierre Bourgin for Plant Sciences (IJPB), 78000, Versailles, France.
Plant J. 2025 Feb;121(4):e70010. doi: 10.1111/tpj.70010.
Plant responses to nutrient availability are critical for plant development and yield. Nitrate, the major form of nitrogen in most soils, serves as both a nutrient and signaling molecule. Nitrate itself triggers rapid, major changes in gene expression, especially via nodule inception (NIN)-like protein (NLP) transcription factors, and stimulates protein phosphorylation. Mitogen-activated protein kinase (MAPK)-related genes are among the early nitrate-responsive genes; however, little is known about their roles in nitrate signaling pathways. Here, we show that nitrate resupply to nitrogen-depleted Arabidopsis (Arabidopsis thaliana) plants triggers, within minutes, an MAPK cascade that requires NLP-dependent transcriptional induction of mitogen-activated protein kinase kinase kinase 13 (MAP3K13) and MAP3K14 and that the MAPK cascade is composed of MKK3 and likely C-clade MAPKs (MPK1/2/7/14). Importantly, nitrate reductase-deficient mutants exhibited nitrate-induced MPK7 activities comparable to those observed in wild-type plants, indicating that nitrate itself is the signal that stimulates the cascade. We show that the modified expression of MAP3K13 and MAP3K14 affects nitrate-stimulated BT2 expression and modulates plant responses to nitrogen availability, such as nitrate uptake and senescence. Our finding that an MAPK cascade involving MAP3K13 and MAP3K14 functions in the complex regulatory network governing responses to nitrate availability will guide future strategies to optimize plant responses to nitrogen fertilization and nitrogen use efficiency.
植物对养分有效性的响应对于植物生长发育和产量至关重要。硝酸盐是大多数土壤中氮的主要存在形式，它既是一种养分，也是一种信号分子。硝酸盐本身会引发基因表达的快速、重大变化，尤其是通过类结瘤起始（NIN）蛋白（NLP）转录因子，并刺激蛋白质磷酸化。丝裂原活化蛋白激酶（MAPK）相关基因是早期硝酸盐响应基因之一；然而，它们在硝酸盐信号通路中的作用却鲜为人知。在这里，我们表明，向缺氮的拟南芥植株重新供应硝酸盐，在几分钟内就会触发一个MAPK级联反应，该反应需要NLP依赖的丝裂原活化蛋白激酶激酶激酶13（MAP3K13）和MAP3K14的转录诱导，并且该MAPK级联反应由MKK3和可能的C类MAPK（MPK1/2/7/14）组成。重要的是，硝酸盐还原酶缺陷型突变体表现出与野生型植株中观察到的相当的硝酸盐诱导的MPK7活性，这表明硝酸盐本身就是刺激该级联反应的信号。我们表明，MAP3K13和MAP3K14的表达改变会影响硝酸盐刺激的BT2表达，并调节植物对氮有效性的响应，如硝酸盐吸收和衰老。我们发现涉及MAP3K13和MAP3K14的MAPK级联反应在控制对硝酸盐有效性响应的复杂调控网络中发挥作用，这将为未来优化植物对氮肥的响应和氮利用效率的策略提供指导。
