Aug 2026· Journal of plant physiology· Vol 325, pp.
154865
· 0 citations· 57 references
Medicine
TL;DR
A novel regulatory pathway that integrates cytokinin signaling, auxin homeostasis, and NH4+ transport is elucidated, providing valuable genetic resources for improving nitrogen-use efficiency and stress tolerance in crops.
Abstract
Ammonium (NH4+) is an essential nitrogen source for plants, yet its excessive accumulation triggers toxicity, a process typically coupled to futile NH4+ cycling in roots cells. While the cytokinin-ARR10/12 signaling pathway is known to regulate vacuolar NH4+ sequestration, it is not known whether it also coordinates NH4+ efflux across the root-cell plasma membrane to maintain intracellular homeostasis. Here, we identify the auxin-amido synthetase GH3.5 as a direct transcriptional target of ARR10, using a combination of yeast one-hybrid (Y1H) assays, dual-luciferase reporter assays, and CUT&RUN-qPCR. We demonstrate that ARR10 directly binds the GH3.5 promoter to repress its transcription, sustaining free IAA levels and inhibiting NH4+ efflux from root cells, whereas ARR12 acts synergistically to potentiate this ARR10-mediated repression through indirect binding to the promoter. Thus, our study reveals that cytokinin signaling, via the ARR10/12 module, represses GH3.5 to suppress NH4+ efflux. This work elucidates a novel regulatory pathway that integrates cytokinin signaling, auxin homeostasis, and NH4+ transport, providing valuable genetic resources for improving nitrogen-use efficiency and stress tolerance in crops.
A positive feedback loop between CLV3 and WUS that is mediated by multiple hormone interactions, which is critical for plants to adapt to harsh environments is revealed.
Mengchu Xu, Haijun Wu, Chengwu Liu et al.· Molecular Plant· 0 citations
Nitrogen (N) is a major determinant of plant growth and productivity. Because soil N availability and internal N demand fluctuate, plants have evolved sophisticated mechanisms to coordinate N acquisition and utilization at the whole-plant level. However, how this coordination is achieved remains poorly understood. Here, we show that N-inducible LATERAL ORGAN BOUNDARIES DOMAIN transcription factors LBD37, LBD38, and LBD39 (LBDs) function as repressors of local N uptake and assimilation and systemic N-demand signaling in Arabidopsis. Triple mutants lacking these three LBDs displayed enhanced nitrate influx and increased accumulation of nitrate, amino acids, and total N. Transcriptome analysis identified an array of N-starvation- and nitrate-inducible genes derepressed in shoots and roots, including C-TERMINALLY ENCODED PEPTIDE (CEP) and CEP DOWNSTREAM (CEPD) genes, as well as genes involved in N uptake and assimilation. Grafting and genetic analyses revealed that LBDs gate the systemic N-demand signaling relay by repressing CEP and CEPD expression organ-autonomously. We also found that LBDs locally repress genes involved in N uptake and assimilation through a distinct regulatory mechanism. We propose that LBDs are key transcriptional repressors in a regulatory framework for optimizing N acquisition and utilization under fluctuating N conditions at the whole-plant level.
Takatoshi Kiba, Hana Takahashi, Kota Monden et al.· bioRxiv· 0 citations
Elucidating the molecular mechanisms underlying ammonium (NH4+)-mediated root system development is critical for alleviating NH4+ toxicity in plants. The Arabidopsis thaliana [Ca2+]cyt-associated protein kinase CAP1 regulates root hair growth in response to NH4+ treatment, with the cap1-1 mutant exhibiting hypersensitivity to NH4+ and elevated reactive oxygen species (ROS) levels. Based on our previous phosphoproteomic data, here we investigated the role of Respiratory Burst Oxidase Homolog D (AtRBOHD) in CAP1-mediated root hair growth under NH4+ treatment. Through yeast two-hybrid (Y2H), bimolecular fluorescence complementation (BiFC), co-immunoprecipitation (Co-IP), and in vitro phosphorylation assays, we demonstrate that CAP1 physically interacts with and phosphorylates RBOHD, with Ser347 identified as a critical phosphorylation site in RBOHD that is required for their interaction. Genetic complementation assays revealed that expressing either wild-type RBOHD or its phospho-mimetic variant (RBOHDS347D) partially restored root hair growth in cap1-1 mutants while reducing ROS levels to those of the wild type under NH4+ treatment. Collectively, our findings establish a mechanistic model in which CAP1 phosphorylates RBOHD at Ser347 to regulate NH4+-dependent root hair growth by modulating ROS homeostasis.
Hong Yang, Lianlian Wang, Yichen Dong et al.· Plant Science· 0 citations
Soil inorganic nitrogen (N) availability is a critical determinant of symbiotic nitrogen fixation efficiency, making it essential for legumes to respond appropriately and effectively to N fluctuations. Here, we identify a pair of high N response factors GmNIGT2a/2b (NITRATE-INDUCIBLE GARP-TYPE TRANSCRIPTIONAL REPRESSOR). GmNIGT2a/2b are activated by GmNLP4a/b (NIN-like proteins) under high N. The nodules of gmnigt2a/2b double mutants exhibit exacerbated reduction in nitrogenase activity and accelerated senescence in response to high N. Integration of RNA-seq and DAP-seq analyses reveals that GmNIGT2a/2b negatively regulate a suite of core N-induced genes, including NAC, WRKY, and bZIP transcription factors as well as trehalose metabolism genes. GmNIGT2b binds to the promoters of SNAP3 and NAC039 and represses their expression, thereby delaying nodule senescence. Our results suggest that GmNIGT2a/2b-mediated transcriptional regulation prevents excessive nodule senescence in response to high N, highlighting the complexity of transcriptional reprogramming for environmental adaptation in nodules.
Tianli Ge, Xiaolei Yao, Yuan Li et al.· Journal of genetics and geno...· 0 citations
It is shown that methyl jasmonate (MeJA) substantially induces HY5 protein accumulation in a FIN219/JAR1-dependent manner, and a regulatory mechanism in which HY5 fine-tunes JA signaling and seedling development by integrating light and hormone cues is uncovered.
Yen-Ho Chen, Meng-Chun Lin, Li-Lin Liao et al.· Frontiers in Plant Science· 0 citations
This study reveals how lipid metabolism, auxin homeostasis, and membrane dynamics intersect to shape hypocotyl adaptive responses, thereby optimizing growth under high‐temperature conditions.
Mohinur Khamzaaliyeva, Punita Lalchand, Didier-Deschamps Ashley et al.· New Phytologist· 0 citations
