Biology subjects

Brehaut, V.

Publications and source records attributed to Brehaut, V..

3 recordsLinked to original sources

bioRxiv2024

Nitrate activates a MKK3-dependent MAPK module via NLP transcription factors in Arabidopsis

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 NIN-LIKE PROTEIN (NLP) transcription factors, and stimulates protein phosphorylation. Mitogen-activated protein (MAP) kinase 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, a MAPK cascade that requires NLP-dependent transcriptional induction of MITOGEN-ACTIVATED PROTEIN KINASE KINASE KINASE 13 (MAP3K13) and MAP3K14. Importantly, nitrate reductase-deficient mutants exhibited nitrate-induced MAPK 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 gene expression and modulates plant responses to nitrogen availability, such as nitrate uptake and senescence. Our finding that a 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. Significance statementNitrate is an essential nutrient that also acts as a signaling molecule to regulate plant metabolism and development. We identified a specific MAPK cascade that is activated by nitrate and regulates several nitrate-dependent responses, such as senescence and nitrate transport.

plant biology↗

bioRxiv2024

Overexpressing NRT2.7 induces nitrate export from the vacuole and increases growth of Arabidopsis

Nitrogen nutrition is essential for crop yield but applying fertilizers has detrimental effects on the environment. Compartmenting nitrate into vacuoles is one of the options to develop Nitrogen-efficient crop adapted to less fertilizers. Only few proteins involved in nitrate transport on the tonoplast have been identified. CLCa is the major transporter involved in nitrate storage in Arabidopsis but it can also facilitate nitrate remobilization from the vacuole in guard cells. Several other nitrate transporters amongst NRT2.7 have been localized in this membrane. The transport mechanism of NRT2.7 has not yet been defined as this protein is present mainly in seed cells that are not easily amenable for electrophysiology analysis. Here, we investigated NRT2.7 function through its ectopic overexpression in a clca knock-out mutant. Although the growth diminution of clca on nitrogen sufficient medium was complemented, nitrate homeostasis was not restored by NRT2.7 activity. Moreover, NRT2.7 ectopic overexpression in wild-type background (WT) increased growth under limiting nitrogen supply, suggesting that NRT2.7 stimulates nitrate efflux from vacuoles. This hypothesis was demonstrated by electrophysiological nitrate flux measurements on isolated vacuoles. This discovery of NRT2.7 function and more largely the coupling of vacuolar nitrate fluxes with growth under low nitrate supply, will enable new strategies for engineering better NUE for a more sustainable agriculture. HighlightThe overexpression of the nitrate transporter NRT2.7 stimulates growth by increasing the export of nitrate from the vacuole, the main cell compartment for nitrate storage.

plant biology↗

bioRxiv2022

The Arabidopsis transcription factor NLP2 regulates early nitrate responses and integrates nitrate assimilation with energy and carbon skeleton supply

Nitrate signaling improves plant growth under limited nitrate availability and, hence, optimal resource use for crop production. Ongoing work has identified several transcriptional regulators of nitrate signaling, including the Arabidopsis thaliana transcription factor NIN-LIKE PROTEIN 7 (NLP7), but additional regulators likely remain to be identified. Here, we characterized Arabidopsis NLP2 as a master upstream transcriptional regulator of early nitrate responses that interacts with NLP7 in vivo and shares key molecular features such as nitrate-dependent nuclear localization, a DNA binding motif, and some target genes with NLP7. Additional genetic, genomic and metabolic approaches revealed a specific role for NLP2 in the nitrate-dependent regulation of carbon and energy-related processes that likely influence plant growth under distinct nitrogen environments. Our findings highlight the complementarity and specificity of NLP2 and NLP7 in orchestrating a multi-tiered nitrate regulatory network that links nitrate assimilation with carbon and energy metabolism for efficient nitrogen use and biomass production. One-sentence summaryNLP2 and NLP7 orchestrate plant responses to nitrate supply and control nitrate- dependent regulation of carbon and energy metabolism.

plant biology↗