Lorenz J Holzner, Lucia Östergaard Frank, Susanne Mühlbauer, Anna Müller, Laura Schröder, Charlotte Seydel, Jennifer Grünert, Rachael A DeTar, Katrin Philippar, Andreas Klingl, David Mendoza-Cózatl, Ute Krämer, Thomas Nägele, Bettina Bölter, Hans-Henning Kunz
Annually, chloroplasts fix 258 billion tons of CO2 through photosynthesis. Photosynthesis and other biochemical pathways require specific amounts of metal ions in the organelle. Transport proteins in the plastid inner envelope maintain the organellar ion homeostasis. Despite substantial progress over the last decades, many genes encoding plastid ion channels and ion carriers or their regulators remain unknown. To fill this knowledge gap, detailed information on the elemental composition of chloroplasts i.e., a plastid ionome, is needed. This will allow us to compare mutants of transporter candidates with wild-type plants. Here, we provide quantitative descriptions of chloroplast ionomes from Arabidopsis thaliana, the metal hyperaccumulator Arabidopsis halleri, Pisum sativum, and Nicotiana benthamiana and analyze similarities and distinctions. Using A. thaliana, we show that plastid ionomes can be genetically manipulated. Chloroplasts of OLIGOPEPTIDE TRANSPORTER3 (OPT3)-deficient mutants contain 14-fold more iron, likely associated with stromal FERRITIN. The removal of FERRITIN in opt3 mutants leads to a substantial decrease in plastid and leaf iron, pointing to an important role of ferritins in shaping the chloroplast ionome. Our study reveals that chloroplast ferritins can be turned into iron sinks. Since crop biofortification to fight hidden hunger has become a global mission, this research provides groundwork to reach this goal.
{"title":"The chloroplast ionome shines light on the dynamics of organellar iron homeostasis","authors":"Lorenz J Holzner, Lucia Östergaard Frank, Susanne Mühlbauer, Anna Müller, Laura Schröder, Charlotte Seydel, Jennifer Grünert, Rachael A DeTar, Katrin Philippar, Andreas Klingl, David Mendoza-Cózatl, Ute Krämer, Thomas Nägele, Bettina Bölter, Hans-Henning Kunz","doi":"10.1093/plcell/koag017","DOIUrl":"https://doi.org/10.1093/plcell/koag017","url":null,"abstract":"Annually, chloroplasts fix 258 billion tons of CO2 through photosynthesis. Photosynthesis and other biochemical pathways require specific amounts of metal ions in the organelle. Transport proteins in the plastid inner envelope maintain the organellar ion homeostasis. Despite substantial progress over the last decades, many genes encoding plastid ion channels and ion carriers or their regulators remain unknown. To fill this knowledge gap, detailed information on the elemental composition of chloroplasts i.e., a plastid ionome, is needed. This will allow us to compare mutants of transporter candidates with wild-type plants. Here, we provide quantitative descriptions of chloroplast ionomes from Arabidopsis thaliana, the metal hyperaccumulator Arabidopsis halleri, Pisum sativum, and Nicotiana benthamiana and analyze similarities and distinctions. Using A. thaliana, we show that plastid ionomes can be genetically manipulated. Chloroplasts of OLIGOPEPTIDE TRANSPORTER3 (OPT3)-deficient mutants contain 14-fold more iron, likely associated with stromal FERRITIN. The removal of FERRITIN in opt3 mutants leads to a substantial decrease in plastid and leaf iron, pointing to an important role of ferritins in shaping the chloroplast ionome. Our study reveals that chloroplast ferritins can be turned into iron sinks. Since crop biofortification to fight hidden hunger has become a global mission, this research provides groundwork to reach this goal.","PeriodicalId":501012,"journal":{"name":"The Plant Cell","volume":"17 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146071647","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Ironing out the details: Fe homeostasis in the shoot and root is regulated by distinct actions of BTS/BTSL1/2 and bHLH IVc subgroup transcription factors.","authors":"Nataliia Konstantinova","doi":"10.1093/plcell/koag012","DOIUrl":"https://doi.org/10.1093/plcell/koag012","url":null,"abstract":"","PeriodicalId":501012,"journal":{"name":"The Plant Cell","volume":"66 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146033847","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Crop yield and sustainability rely on the ability of plants to perceive and efficiently use nutrients. When high carbon (C) to nitrogen (N) ratios are perceived, plants trigger a specific response leading to reduced growth and enhanced anthocyanin accumulation. Here, using (Arabidopsis thaliana), we provide genetic, molecular and physiological evidence supporting a role for DELLA proteins to control growth under C/N stress through a non-nuclear mechanism that regulates their stability. C/N stress response specifically requires the RGA (REPRESSOR OF ga1-3 1) and GAI (GIBBERELLIC ACID INSENSITIVE) DELLA proteins, whose stability is reduced by a membrane-associated mechanism independent of the canonical gibberellic acid (GA)-GID1 (GIBBERELLIN INSENSITIVE DWARF1) pathway. Although C/N stress enhances DELLA accumulation by reducing GA levels, it also promotes their ubiquitination and degradation via interaction with the ATL31 E3-ligase at the membrane, even in the absence of GAs or when GA-resistant alleles are used. Moreover, phenotypic traits known to be altered by DELLA levels are not affected by enhanced ATL31 expression in the absence of stress. We propose that this mechanism fine-tunes DELLA-mediated C/N stress responses without adverse effects on plant development.
{"title":"Membrane-associated DELLA degradation modulates growth under carbon/nitrogen imbalance.","authors":"Gerardo Carrera-Castaño,Iris Fañanás-Pueyo,Laura Celada-Bustillos,Julián Calleja-Cabrera,Héctor Molinelli-Rubiato,Ángela Contreras,Jan Eric Maika,Rüdiger Simon,Mónica Pernas,Luis Gómez,Luis Oñate-Sánchez","doi":"10.1093/plcell/koag013","DOIUrl":"https://doi.org/10.1093/plcell/koag013","url":null,"abstract":"Crop yield and sustainability rely on the ability of plants to perceive and efficiently use nutrients. When high carbon (C) to nitrogen (N) ratios are perceived, plants trigger a specific response leading to reduced growth and enhanced anthocyanin accumulation. Here, using (Arabidopsis thaliana), we provide genetic, molecular and physiological evidence supporting a role for DELLA proteins to control growth under C/N stress through a non-nuclear mechanism that regulates their stability. C/N stress response specifically requires the RGA (REPRESSOR OF ga1-3 1) and GAI (GIBBERELLIC ACID INSENSITIVE) DELLA proteins, whose stability is reduced by a membrane-associated mechanism independent of the canonical gibberellic acid (GA)-GID1 (GIBBERELLIN INSENSITIVE DWARF1) pathway. Although C/N stress enhances DELLA accumulation by reducing GA levels, it also promotes their ubiquitination and degradation via interaction with the ATL31 E3-ligase at the membrane, even in the absence of GAs or when GA-resistant alleles are used. Moreover, phenotypic traits known to be altered by DELLA levels are not affected by enhanced ATL31 expression in the absence of stress. We propose that this mechanism fine-tunes DELLA-mediated C/N stress responses without adverse effects on plant development.","PeriodicalId":501012,"journal":{"name":"The Plant Cell","volume":"178 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146033846","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Positive-strand RNA [(+)RNA] viruses induce endomembrane remodeling to form viral replication organelles (VROs), which disrupt organelle homeostasis. How hosts restore organelle homeostasis and how these responses influence viral replication remain elusive. Using beet black scorch virus (BBSV), a (+)RNA virus that replicates on the endoplasmic reticulum (ER) and induces severe deformation of ER membranes, as a model in Nicotiana benthamiana, we demonstrated that BBSV induces ER-phagy, primarily mediated by its auxiliary replication protein p23. p23 interacts with the ER-phagy receptor NbSec62, with phenylalanine at position 48 being critical for this interaction and ER-phagy induction. Upon BBSV infection, the unfolded protein response (UPR) is triggered to promote viral replication. However, the activation of the UPR also induces NbSec62-mediated ER-phagy to suppress BBSV replication. Furthermore, NbSec62 restricts other ER-replicating (+)RNA viruses, including tobacco mosaic virus and turnip mosaic virus. Our findings reveal NbSec62 as a restriction factor that interacts with BBSV VROs to regulate the balance of viral replication and ER homeostasis, providing insights into the UPR–ER-phagy signaling network in virus–host interactions.
{"title":"Sec62 restricts ER-replicating positive-strand RNA virus infections via UPR-dependent ER-phagy","authors":"Ruiqi Wang, Qianshen Zhang, Lifan Zhou, Dingliang Zhang, Yiping Wang, Xinyu Zhang, Xiuling Cao, Chenchen Zhong, Xiaofei Zhao, Meng Yang, Dawei Li, Xiaofeng Wang, Yongliang Zhang","doi":"10.1093/plcell/koag014","DOIUrl":"https://doi.org/10.1093/plcell/koag014","url":null,"abstract":"Positive-strand RNA [(+)RNA] viruses induce endomembrane remodeling to form viral replication organelles (VROs), which disrupt organelle homeostasis. How hosts restore organelle homeostasis and how these responses influence viral replication remain elusive. Using beet black scorch virus (BBSV), a (+)RNA virus that replicates on the endoplasmic reticulum (ER) and induces severe deformation of ER membranes, as a model in Nicotiana benthamiana, we demonstrated that BBSV induces ER-phagy, primarily mediated by its auxiliary replication protein p23. p23 interacts with the ER-phagy receptor NbSec62, with phenylalanine at position 48 being critical for this interaction and ER-phagy induction. Upon BBSV infection, the unfolded protein response (UPR) is triggered to promote viral replication. However, the activation of the UPR also induces NbSec62-mediated ER-phagy to suppress BBSV replication. Furthermore, NbSec62 restricts other ER-replicating (+)RNA viruses, including tobacco mosaic virus and turnip mosaic virus. Our findings reveal NbSec62 as a restriction factor that interacts with BBSV VROs to regulate the balance of viral replication and ER homeostasis, providing insights into the UPR–ER-phagy signaling network in virus–host interactions.","PeriodicalId":501012,"journal":{"name":"The Plant Cell","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146056257","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Beyond sequences: Structure-guided discovery of novel protein functions in plants.","authors":"Crispus M Mbaluto","doi":"10.1093/plcell/koag009","DOIUrl":"https://doi.org/10.1093/plcell/koag009","url":null,"abstract":"","PeriodicalId":501012,"journal":{"name":"The Plant Cell","volume":"6 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146005106","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Acidification of the battlefield: How Pst manipulates apoplastic pH homeostasis to promote stripe rust disease in wheat.","authors":"Margot Raffeiner","doi":"10.1093/plcell/koag010","DOIUrl":"https://doi.org/10.1093/plcell/koag010","url":null,"abstract":"","PeriodicalId":501012,"journal":{"name":"The Plant Cell","volume":"20 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145986352","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In most flowering plants, a single hypodermal cell from the ovule primordium differentiates into the megaspore mother cell (MMC) to initiate the female germline. However, how positional cues maintain this cell identity remains unclear. Here, we report that in Arabidopsis (Arabidopsis thaliana), the basic helix-loop-helix transcription factor genes PACLOBUTRAZOL RESISTANCE 1 (PRE1) and PRE2/3/5/6 (referred to as PREs), are expressed in the distal nucellus domain of ovule primordia. PRE proteins accumulate near the chalaza region of the ovule primordia, where the cytochrome P450 gene KLU (KLUH/CYP78A5)is also expressed. Ectopic expression of PREs driven by the KLU promoter or misexpression of KLU in the distal end of the ovule primordia caused the development of extra MMC-like cells. In the klu mutant, PRE protein localization extended towards the inner integument primordia and chalaza region. KLU physically interacts with PREs depending on the PRE M8 motif. The transcription factor BRASSINAZOLE-RESISTANT1 (BZR1) directly targets the PRE and KLU promoters and is expressed in all ovule primordia cells except the MMC. BZR1 physically interacts with SWR1 COMPLEX 6 (SWC6), and together they affect the chromatin state at PRE loci. In summary, the KLU-PRE module integrates brassinosteroid signaling with chromatin remodeling to establish positional cues that restrict MMC differentiation and female germline initiation to a single cell in Arabidopsis.
{"title":"The KLU-PRE module provides positional cues that maintain somatic cell identity around the megasporocyte cell in Arabidopsis.","authors":"Hanyang Cai,Youmei Huang,Liping Liu,Han Su,Xinpeng Xi,Yanfen Liu,Thomas Dresselhaus,Yuan Qin","doi":"10.1093/plcell/koag008","DOIUrl":"https://doi.org/10.1093/plcell/koag008","url":null,"abstract":"In most flowering plants, a single hypodermal cell from the ovule primordium differentiates into the megaspore mother cell (MMC) to initiate the female germline. However, how positional cues maintain this cell identity remains unclear. Here, we report that in Arabidopsis (Arabidopsis thaliana), the basic helix-loop-helix transcription factor genes PACLOBUTRAZOL RESISTANCE 1 (PRE1) and PRE2/3/5/6 (referred to as PREs), are expressed in the distal nucellus domain of ovule primordia. PRE proteins accumulate near the chalaza region of the ovule primordia, where the cytochrome P450 gene KLU (KLUH/CYP78A5)is also expressed. Ectopic expression of PREs driven by the KLU promoter or misexpression of KLU in the distal end of the ovule primordia caused the development of extra MMC-like cells. In the klu mutant, PRE protein localization extended towards the inner integument primordia and chalaza region. KLU physically interacts with PREs depending on the PRE M8 motif. The transcription factor BRASSINAZOLE-RESISTANT1 (BZR1) directly targets the PRE and KLU promoters and is expressed in all ovule primordia cells except the MMC. BZR1 physically interacts with SWR1 COMPLEX 6 (SWC6), and together they affect the chromatin state at PRE loci. In summary, the KLU-PRE module integrates brassinosteroid signaling with chromatin remodeling to establish positional cues that restrict MMC differentiation and female germline initiation to a single cell in Arabidopsis.","PeriodicalId":501012,"journal":{"name":"The Plant Cell","volume":"40 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145986354","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Iron (Fe) deficiency threatens plant growth and health. In response to Fe deficiency, plants reprogram transcription in roots and shoots to maintain Fe homeostasis. However, the molecular mechanism by which Arabidopsis (Arabidopsis thaliana) plants coordinate Fe deficiency responses in the root and shoot remains unclear. Here, we uncover the roles of BRUTUS (BTS), BTS-LIKE1 (BTSL1), and BTSL2, along with the bHLH IVc subgroup proteins (bHLH34, bHLH104, bHLH105, and bHLH115), in orchestrating the Fe deficiency responses of roots and shoots in Arabidopsis. BTS relieves shoot Fe toxicity and regulates Fe deficiency responses of shoots and roots, but BTSL1/2 are only involved in root Fe-deficiency responses. Furthermore, BTSL1/2 share similar molecular functions with BTS to a certain extent, as they also interact with bHLH IVc proteins and promote the degradation of bHLH105 and bHLH115. The simultaneous loss of the four bHLH IVc proteins completely halts the Fe deficiency responses across the whole plant. Moreover, bHLH IVc proteins are essential for BTSL1/2 functions in Fe deficiency responses. Meanwhile, bHLH IVc proteins directly enhance BTSL1/2 expression. This research sheds light on the distinct roles of BTS and BTSL1/2 in the root and shoot and emphasizes crucial roles of bHLH IVc proteins in regulating Fe deficiency responses in the root and shoot.
{"title":"Arabidopsis BRUTUS, BRUTUS-LIKE, and bHLH IVc subgroup proteins coordinate iron homeostasis in the root and shoot.","authors":"Junhui Zhao,Yang Li,Huaqian Ping,Rihua Lei,Bangzhen Pan,Gang Liang","doi":"10.1093/plcell/koag006","DOIUrl":"https://doi.org/10.1093/plcell/koag006","url":null,"abstract":"Iron (Fe) deficiency threatens plant growth and health. In response to Fe deficiency, plants reprogram transcription in roots and shoots to maintain Fe homeostasis. However, the molecular mechanism by which Arabidopsis (Arabidopsis thaliana) plants coordinate Fe deficiency responses in the root and shoot remains unclear. Here, we uncover the roles of BRUTUS (BTS), BTS-LIKE1 (BTSL1), and BTSL2, along with the bHLH IVc subgroup proteins (bHLH34, bHLH104, bHLH105, and bHLH115), in orchestrating the Fe deficiency responses of roots and shoots in Arabidopsis. BTS relieves shoot Fe toxicity and regulates Fe deficiency responses of shoots and roots, but BTSL1/2 are only involved in root Fe-deficiency responses. Furthermore, BTSL1/2 share similar molecular functions with BTS to a certain extent, as they also interact with bHLH IVc proteins and promote the degradation of bHLH105 and bHLH115. The simultaneous loss of the four bHLH IVc proteins completely halts the Fe deficiency responses across the whole plant. Moreover, bHLH IVc proteins are essential for BTSL1/2 functions in Fe deficiency responses. Meanwhile, bHLH IVc proteins directly enhance BTSL1/2 expression. This research sheds light on the distinct roles of BTS and BTSL1/2 in the root and shoot and emphasizes crucial roles of bHLH IVc proteins in regulating Fe deficiency responses in the root and shoot.","PeriodicalId":501012,"journal":{"name":"The Plant Cell","volume":"9 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145986353","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：