Pub Date : 2026-02-12DOI: 10.1038/s41477-026-02225-8
Xiaofei Zhang, Shanmin Zhou, Jingyi Guo, Ricardo F H Giehl, Xiaodong Xu, Lixing Yuan, Fusuo Zhang, Malcolm J Bennett, Nicolaus von Wirén, Zhongtao Jia
In eucaryotes, mitogen-activated protein kinase (MAPK) cascades are evolutionarily conserved signalling modules crucial for growth regulation and stress tolerance. However, the regulatory role of MAPK in nutrient sensing by plants remains largely unclear. Here we uncovered MEKK14 and its paralogue MEKK13 determine lateral root elongation via enhanced cell division and expansion. We further fine-mapped a naturally occurring histidine-to-glutamine substitution in MEKK14 that weakens protein kinase activity and attenuates lateral root growth and response to nitrate (NO3-). We further demonstrate that NO3- transcriptionally upregulates MEKK13/14 depending on NLP7 to activate a MKK3-MPK1/2/7/14 signalling module. Downstream of this signalling cascade, the core oscillator of the circadian clock CCA1 is phosphorylated and stabilized to feedback induce MEKK13/14 expression and to activate auxin signalling-dependent lateral root foraging for NO3-. Our findings reveal a positive-feedback phosphorylation-transcriptional regulatory loop in root NO3- foraging, extending the regulatory function of MAPK signalling in the nutrient sensing.
{"title":"A feedback regulatory loop by MAPK-CCA1 engages auxin signalling to stimulate root foraging for nitrate.","authors":"Xiaofei Zhang, Shanmin Zhou, Jingyi Guo, Ricardo F H Giehl, Xiaodong Xu, Lixing Yuan, Fusuo Zhang, Malcolm J Bennett, Nicolaus von Wirén, Zhongtao Jia","doi":"10.1038/s41477-026-02225-8","DOIUrl":"https://doi.org/10.1038/s41477-026-02225-8","url":null,"abstract":"<p><p>In eucaryotes, mitogen-activated protein kinase (MAPK) cascades are evolutionarily conserved signalling modules crucial for growth regulation and stress tolerance. However, the regulatory role of MAPK in nutrient sensing by plants remains largely unclear. Here we uncovered MEKK14 and its paralogue MEKK13 determine lateral root elongation via enhanced cell division and expansion. We further fine-mapped a naturally occurring histidine-to-glutamine substitution in MEKK14 that weakens protein kinase activity and attenuates lateral root growth and response to nitrate (NO<sub>3</sub><sup>-</sup>). We further demonstrate that NO<sub>3</sub><sup>-</sup> transcriptionally upregulates MEKK13/14 depending on NLP7 to activate a MKK3-MPK1/2/7/14 signalling module. Downstream of this signalling cascade, the core oscillator of the circadian clock CCA1 is phosphorylated and stabilized to feedback induce MEKK13/14 expression and to activate auxin signalling-dependent lateral root foraging for NO<sub>3</sub><sup>-</sup>. Our findings reveal a positive-feedback phosphorylation-transcriptional regulatory loop in root NO<sub>3</sub><sup>-</sup> foraging, extending the regulatory function of MAPK signalling in the nutrient sensing.</p>","PeriodicalId":18904,"journal":{"name":"Nature Plants","volume":" ","pages":""},"PeriodicalIF":13.6,"publicationDate":"2026-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146181171","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-10DOI: 10.1038/s41477-026-02227-6
Kun Zang, Xiaoyu Hong, Nghiem D. Nguyen, Loraine M. Rourke, Jiwon Lee, Benedict M. Long, G. Dean Price, Manajit Hayer-Hartl
Cyanobacteria have evolved a CO2-concentrating mechanism (CCM) in the form of a microcompartment with a proteinaceous shell called carboxysome, harbouring the photosynthetic enzyme Rubisco and carbonic anhydrase (CA). β-Carboxysome assembly proceeds by an inside-out process, in which Rubisco, CA and the shell adaptor protein ApN (also known as CcmN) first form the pro-carboxysome biomolecular condensate mediated by the scaffolding protein CM (also known as CcmM). How ApN assembles into the pro-carboxysome as a prerequisite for shell formation has remained unclear. Here we show that ApN is recruited to the periphery of the pro-carboxysome as a hetero-complex of three ApN protomers and one CM protomer. The association of (ApN)3:CM at the rim of the pro-carboxysome ensures that shell formation and maturation of the carboxysome proceeds only after assembly of the two enzymes, Rubisco and CA, to form the pro-carboxysome core. These results provide mechanistic insight into a critical step of β-carboxysome assembly, informing efforts to introduce a cyanobacterial CCM into plants. Carboxysomes are cyanobacterial CO2-concentrating compartments with a proteinaceous shell. The elucidation of the role of the shell adaptor protein ApN in stepwise β-carboxysome assembly will aid the engineering of these structures in plants.
{"title":"Stages of biomolecular condensate formation in pro-β-carboxysome assembly","authors":"Kun Zang, Xiaoyu Hong, Nghiem D. Nguyen, Loraine M. Rourke, Jiwon Lee, Benedict M. Long, G. Dean Price, Manajit Hayer-Hartl","doi":"10.1038/s41477-026-02227-6","DOIUrl":"10.1038/s41477-026-02227-6","url":null,"abstract":"Cyanobacteria have evolved a CO2-concentrating mechanism (CCM) in the form of a microcompartment with a proteinaceous shell called carboxysome, harbouring the photosynthetic enzyme Rubisco and carbonic anhydrase (CA). β-Carboxysome assembly proceeds by an inside-out process, in which Rubisco, CA and the shell adaptor protein ApN (also known as CcmN) first form the pro-carboxysome biomolecular condensate mediated by the scaffolding protein CM (also known as CcmM). How ApN assembles into the pro-carboxysome as a prerequisite for shell formation has remained unclear. Here we show that ApN is recruited to the periphery of the pro-carboxysome as a hetero-complex of three ApN protomers and one CM protomer. The association of (ApN)3:CM at the rim of the pro-carboxysome ensures that shell formation and maturation of the carboxysome proceeds only after assembly of the two enzymes, Rubisco and CA, to form the pro-carboxysome core. These results provide mechanistic insight into a critical step of β-carboxysome assembly, informing efforts to introduce a cyanobacterial CCM into plants. Carboxysomes are cyanobacterial CO2-concentrating compartments with a proteinaceous shell. The elucidation of the role of the shell adaptor protein ApN in stepwise β-carboxysome assembly will aid the engineering of these structures in plants.","PeriodicalId":18904,"journal":{"name":"Nature Plants","volume":"12 2","pages":"447-464"},"PeriodicalIF":13.6,"publicationDate":"2026-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.comhttps://www.nature.com/articles/s41477-026-02227-6.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146152310","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-09DOI: 10.1038/s41477-025-02218-z
Ryan Toth, Sera Choi, Marie Le Naour--Vernet, Florian Schwanke, Jared L. Johnson, Estee E. Tee, Tomer M. Yaron-Barir, Eleanor Khochaba, Paul Derbyshire, Anka Colo, Philipp Köster, Emily M. Huntsman, Laura Herold, Yoonyoung Lee, Álvaro D. Fernández-Fernández, Hee-Kyung Ahn, Julian Dindas, Marta Bjornson, Jack Rhodes, Beibei Song, Weibing Wang, Marija Smokvarska, Emmanuelle M. Bayer, Jian-Min Zhou, Lewis C. Cantley, Jonathan D. G. Jones, Kyle W. Bender, Frank L. H. Menke, Christine Faulkner, Cyril Zipfel, Thomas A. DeFalco
Plant cell surface pattern recognition receptors (PRRs) perceive non- or altered-self elicitors to induce immune responses. PRRs relay information across the plasma membrane and trigger downstream signalling via receptor-like cytoplasmic kinases such as BOTRYTIS-INDUCED KINASE 1 (BIK1). BIK1 associates with several PRRs and acts as a key executor of immune responses through the phosphorylation of substrate proteins. However, a comprehensive understanding of how BIK1 targets specific substrates and a full repertoire of these substrates are lacking. Here we defined the substrate specificity of BIK1 and used these data to predict candidate substrates in Arabidopsis. Using high-throughput biochemical and genetic screening of these candidates, we confirmed many as direct BIK1 substrates in vitro and novel regulators of plant immunity. Among the BIK1 substrates identified are MULTIPLE C2 DOMAIN AND TRANSMEMBRANE REGION PROTEIN 3, which we reveal regulates flagellin 22 (flg22)-induced plasmodesmata closure and immunity, and members of the largely uncharacterized CYCLIN-DEPENDENT KINASE-LIKE family, which we uncover as novel negative regulators of immunity. In parallel, we interrogated intracellular NUCLEOTIDE-BINDING LEUCINE-RICH REPEAT (NLR) immune receptors for potential BIK1 phosphorylation motifs and identified multiple NLRs as direct BIK1 substrates. We reveal that BIK1 phosphorylation regulates NLR oligomerization, thus controlling a key activation step for these immune receptors. Together, our unbiased biochemical screens shed light on the central role of BIK1 as a key kinase shaping multiple layers of plant immune signalling. Cell surface receptors perceive immunogenic elicitors, triggering downstream signalling via receptor-like cytoplasmic kinases such as BIK1. Here the authors define and use the phosphorylation motif of BIK1 to find novel substrate candidates.
{"title":"Motif-based substrate mapping of the receptor-like cytoplasmic kinase BIK1 reveals novel components and regulatory nodes of plant immunity","authors":"Ryan Toth, Sera Choi, Marie Le Naour--Vernet, Florian Schwanke, Jared L. Johnson, Estee E. Tee, Tomer M. Yaron-Barir, Eleanor Khochaba, Paul Derbyshire, Anka Colo, Philipp Köster, Emily M. Huntsman, Laura Herold, Yoonyoung Lee, Álvaro D. Fernández-Fernández, Hee-Kyung Ahn, Julian Dindas, Marta Bjornson, Jack Rhodes, Beibei Song, Weibing Wang, Marija Smokvarska, Emmanuelle M. Bayer, Jian-Min Zhou, Lewis C. Cantley, Jonathan D. G. Jones, Kyle W. Bender, Frank L. H. Menke, Christine Faulkner, Cyril Zipfel, Thomas A. DeFalco","doi":"10.1038/s41477-025-02218-z","DOIUrl":"10.1038/s41477-025-02218-z","url":null,"abstract":"Plant cell surface pattern recognition receptors (PRRs) perceive non- or altered-self elicitors to induce immune responses. PRRs relay information across the plasma membrane and trigger downstream signalling via receptor-like cytoplasmic kinases such as BOTRYTIS-INDUCED KINASE 1 (BIK1). BIK1 associates with several PRRs and acts as a key executor of immune responses through the phosphorylation of substrate proteins. However, a comprehensive understanding of how BIK1 targets specific substrates and a full repertoire of these substrates are lacking. Here we defined the substrate specificity of BIK1 and used these data to predict candidate substrates in Arabidopsis. Using high-throughput biochemical and genetic screening of these candidates, we confirmed many as direct BIK1 substrates in vitro and novel regulators of plant immunity. Among the BIK1 substrates identified are MULTIPLE C2 DOMAIN AND TRANSMEMBRANE REGION PROTEIN 3, which we reveal regulates flagellin 22 (flg22)-induced plasmodesmata closure and immunity, and members of the largely uncharacterized CYCLIN-DEPENDENT KINASE-LIKE family, which we uncover as novel negative regulators of immunity. In parallel, we interrogated intracellular NUCLEOTIDE-BINDING LEUCINE-RICH REPEAT (NLR) immune receptors for potential BIK1 phosphorylation motifs and identified multiple NLRs as direct BIK1 substrates. We reveal that BIK1 phosphorylation regulates NLR oligomerization, thus controlling a key activation step for these immune receptors. Together, our unbiased biochemical screens shed light on the central role of BIK1 as a key kinase shaping multiple layers of plant immune signalling. Cell surface receptors perceive immunogenic elicitors, triggering downstream signalling via receptor-like cytoplasmic kinases such as BIK1. Here the authors define and use the phosphorylation motif of BIK1 to find novel substrate candidates.","PeriodicalId":18904,"journal":{"name":"Nature Plants","volume":"12 2","pages":"465-480"},"PeriodicalIF":13.6,"publicationDate":"2026-02-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.comhttps://www.nature.com/articles/s41477-025-02218-z.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146150158","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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