The Plant Cell最新文献

ZmSSRP1 facilitates the progression of RNA polymerase II and is essential for kernel development in maize

The Plant Cell Pub Date : 2025-03-31 DOI: 10.1093/plcell/koaf071

Jin-Yu Wang, Qi Wang, Ye-Xiang Peng, Lu-Guang Jiang, Zi-Zheng Lu, Lei-Ming Zheng, Xiao-Han Li, Juan Liu, Jin-Cheng Long, Jing-Han Liu, Yan He

{"title":"ZmSSRP1 facilitates the progression of RNA polymerase II and is essential for kernel development in maize","authors":"Jin-Yu Wang, Qi Wang, Ye-Xiang Peng, Lu-Guang Jiang, Zi-Zheng Lu, Lei-Ming Zheng, Xiao-Han Li, Juan Liu, Jin-Cheng Long, Jing-Han Liu, Yan He","doi":"10.1093/plcell/koaf071","DOIUrl":"https://doi.org/10.1093/plcell/koaf071","url":null,"abstract":"Transcript elongation controlled by RNA polymerase II (RNAP II) represents a key regulatory event in numerous cellular processes. However, the precise mechanisms underlying the regulation of RNAP II distribution and progression in plants remain largely elusive. Here, we positionally cloned the causal mutation in the defective kernel 59 (dek59) maize (Zea mays) mutant and demonstrated that Dek59 encodes Structure-Specific Recognition-Protein 1 (ZmSSRP1), a subunit of the Facilitates Chromatin Transcription (FACT) complex that regulates RNAP II. Using genome-wide mapping assays, we determined that ZmSSRP1 binding sites co-localize with those of RNAP II phosphorylated at its serine 2 residue (Ser2P) and are highly enriched within actively transcribed genes. Mutation of ZmSSRP1 resulted in Ser2P accumulation around the +1 nucleosome of genes, affecting gene expression in a gene length-dependent manner. The reduced amount of RNAP II in the dek59 mutant was rescued to wild-type-like levels by inhibiting the proteasome, indicating that arrested RNAP II degradation is proteasome-dependent. These findings reveal the indispensable role of ZmSSRP1 in regulating RNAP II-mediated transcription, which is critical for the proper expression of thousands of genes during maize seed development.","PeriodicalId":501012,"journal":{"name":"The Plant Cell","volume":"8 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143745127","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}

引用次数: 0

The kinesin motor POS3 and the microtubule polymerase MOR1 coordinate chromosome congression during mitosis in Arabidopsis

The Plant Cell Pub Date : 2025-03-17 DOI: 10.1093/plcell/koaf053

Yu Chen, Haofeng Liu, Yuanfeng Li, Xiao Shen, Shuting Li, Lan Yang, Xue An, Pei Lei, Xiaomin Wang, Hongchang Zhang, Jen Sheen, Fei Yu, Xiayan Liu

{"title":"The kinesin motor POS3 and the microtubule polymerase MOR1 coordinate chromosome congression during mitosis in Arabidopsis","authors":"Yu Chen, Haofeng Liu, Yuanfeng Li, Xiao Shen, Shuting Li, Lan Yang, Xue An, Pei Lei, Xiaomin Wang, Hongchang Zhang, Jen Sheen, Fei Yu, Xiayan Liu","doi":"10.1093/plcell/koaf053","DOIUrl":"https://doi.org/10.1093/plcell/koaf053","url":null,"abstract":"Faithful chromosome segregation during mitosis is crucial for eukaryotic organisms. Centromere-associated protein E (CENP-E), a kinetochore-localized kinesin motor, facilitates chromosome congression during mitosis in animals. However, it remains unclear whether plants rely on kinesins similar to CENP-E for chromosome alignment. In our genetic screens for Arabidopsis (Arabidopsis thaliana) mutants that are hypersensitive to the microtubule-destabilizing drug propyzamide, we identified propyzamide oversensitive3-1 (pos3-1), which harbors a mutation in a kinesin-like protein that shares sequence similarity with the N-terminal region of CENP-E. We demonstrated that POS3 dynamically associates with kinetochores during chromosome congression and segregation in mitosis. Moreover, loss of POS3 results in prolonged mitosis, increased aneuploidy, and misaligned chromosomes near the spindle poles. Unexpectedly, we discovered a direct physical interaction and functional link between POS3 and the microtubule polymerase MICROTUBULE ORGANIZATION1 (MOR1) in regulating chromosome alignment and segregation during mitosis. Finally, we showed that MOR1 is required for the kinetochore localization of POS3 in mitosis. Together, our findings establish the vital role of POS3 in chromosome congression and uncover a functional link between POS3 and MOR1 that is essential for proper chromosome alignment and segregation in plant mitosis.","PeriodicalId":501012,"journal":{"name":"The Plant Cell","volume":"44 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143641104","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}

引用次数: 0

Complexome profiling of the Chlamydomonas psb28 mutant reveals TEF5 as an early photosystem II assembly factor

The Plant Cell Pub Date : 2025-03-17 DOI: 10.1093/plcell/koaf055

Julia Lang, Katharina König, Benedikt Venn, Saskia Zeilfelder, Matthias Ostermeier, Benjamin Spaniol, Lara Spaniol, Frederik Sommer, Matthieu Mustas, Stefan Geimer, Torben Fürtges, Pawel Brzezowski, Jure Zabret, Francis-André Wollman, Marc M Nowacyzk, David Scheuring, Till Rudack, Timo Mühlhaus, Yves Choquet, Michael Schroda

{"title":"Complexome profiling of the Chlamydomonas psb28 mutant reveals TEF5 as an early photosystem II assembly factor","authors":"Julia Lang, Katharina König, Benedikt Venn, Saskia Zeilfelder, Matthias Ostermeier, Benjamin Spaniol, Lara Spaniol, Frederik Sommer, Matthieu Mustas, Stefan Geimer, Torben Fürtges, Pawel Brzezowski, Jure Zabret, Francis-André Wollman, Marc M Nowacyzk, David Scheuring, Till Rudack, Timo Mühlhaus, Yves Choquet, Michael Schroda","doi":"10.1093/plcell/koaf055","DOIUrl":"https://doi.org/10.1093/plcell/koaf055","url":null,"abstract":"Photosystem (PS) II assembly requires auxiliary factors, including Psb28. Although the absence of Psb28 in cyanobacteria has little effect on PSII assembly, we show here that the Chlamydomonas (Chlamydomonas reinhardtii) psb28 null mutant is severely impaired in PSII assembly, showing drastically reduced PSII supercomplexes, dimers and monomers, while overaccumulating early PSII assembly intermediates reaction center II (RCII), CP43mod and D1mod. The mutant had less PSI and more cytochrome b6f complex, its thylakoids were organized mainly as monolayers and it had a distorted chloroplast morphology. Complexome profiling of the psb28 mutant revealed that THYLAKOID ENRICHED FRACTION 5 (TEF5), the homolog of Arabidopsis (Arabidopsis thaliana) PHOTOSYSTEM B PROTEIN 33 (PSB33)/LIGHT HARVESTING-LIKE 8 (LIL8), co-migrated particularly with RCII. TEF5 also interacted with PSI. A Chlamydomonas tef5 null mutant was severely impaired in PSII assembly and overaccumulated RCII and CP43mod. RC47 was not detectable in the light-grown tef5 mutant. Our data suggest a possible role for TEF5 in RCII photoprotection or maturation. Both the psb28 and tef5 mutants exhibited decreased synthesis of CP47 and PsbH, suggesting negative feedback regulation possibly exerted by the accumulation of RCII and/or CP43mod in both mutants. The strong effects of missing auxiliary factors on PSII assembly in Chlamydomonas suggest a more effective protein quality control system in this alga than in land plants and cyanobacteria.","PeriodicalId":501012,"journal":{"name":"The Plant Cell","volume":"20 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143641106","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}

引用次数: 0

Novel repetitive elements in plant-specific tails of Gγ proteins as the functional unit in G-protein signalling in crops 植物特异性 Gγ 蛋白尾部的新重复元件是农作物 G 蛋白信号的功能单元

The Plant Cell Pub Date : 2025-03-15 DOI: 10.1093/plcell/koaf052

Shengyuan Sun, Jinliang Cheng, Yiwen Zhang, Yifei Wang, Lei Wang, Tian Wang, Zhengji Wang, Xu Li, Yong Zhou, Xianghua Li, Jinghua Xiao, Changjie Yan, Qifa Zhang, Yidan Ouyang

{"title":"Novel repetitive elements in plant-specific tails of Gγ proteins as the functional unit in G-protein signalling in crops","authors":"Shengyuan Sun, Jinliang Cheng, Yiwen Zhang, Yifei Wang, Lei Wang, Tian Wang, Zhengji Wang, Xu Li, Yong Zhou, Xianghua Li, Jinghua Xiao, Changjie Yan, Qifa Zhang, Yidan Ouyang","doi":"10.1093/plcell/koaf052","DOIUrl":"https://doi.org/10.1093/plcell/koaf052","url":null,"abstract":"Heterotrimeric G proteins act as molecular switches in signal transduction in response to stimuli in all eukaryotes. However, what specifies G protein signalling in plants and how the mechanism evolved and diverged remain unsolved. Here, we found that the recently evolved tails of three Gγ subunits, Dense and erect panicle 1 (DEP1), G protein gamma subunit 2 of type C (GGC2), and Grain size 3 (GS3), determine their distinct functions and specify grain size in rice (Oryza sativa L.). These Gγ subunits originated and expanded by an ancestral σ duplication ∼130 million years ago (mya) and a pancereal ρ duplication ∼70 mya in monocots, increasing genome complexity and inspiring functional innovations. In particular, through the comprehensive creation of artificial chimeric Gγ proteins, we found that this signalling selectivity is driven by repetitive elements and a link region hidden in plant-specific Gγ tails, allowing crops to switch from positive regulation to negative control. Unlike the tails, the conserved Gγ heads did not bias the signalling specificity; however, the change in the interaction between the mutated Gβ and Gγ affected the subsequent downstream signal transduction and grain size. Manipulating G protein signalling also affects organ size in maize (Zea mays) and is expected to constitute a general mechanism for crop improvement. Collectively, these findings reveal that plant-specific Gγ tails drive signaling selectivity and serve as valuable targets for optimizing crop traits through G protein manipulation.","PeriodicalId":501012,"journal":{"name":"The Plant Cell","volume":"16 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143631370","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}

引用次数: 0

Noncoding RNAs as Tools for Advancing Translational Biology in Plants

The Plant Cell Pub Date : 2025-03-14 DOI: 10.1093/plcell/koaf054

Carolina Attallah, Gabriela Conti, Federico Zuljan, Diego Zavallo, Federico Ariel

{"title":"Noncoding RNAs as Tools for Advancing Translational Biology in Plants","authors":"Carolina Attallah, Gabriela Conti, Federico Zuljan, Diego Zavallo, Federico Ariel","doi":"10.1093/plcell/koaf054","DOIUrl":"https://doi.org/10.1093/plcell/koaf054","url":null,"abstract":"Noncoding RNAs (ncRNAs), once considered the \"dark matter\" of the genome, have emerged as critical regulators of gene expression in plants. Research initially focused on model organisms has laid the groundwork for harnessing the potential of ncRNAs in agriculture, particularly for crop protection, improvement and modulation. This review explores the role of long and small ncRNAs in plant biology, highlighting their application as powerful tools in agricultural biotechnology. We examine the latest strategies for ncRNA expression and delivery in crops, including transgenic and non-transgenic approaches, as well as emerging technologies that enable precise and efficient modulation of gene activity in plants and pathogens. Additionally, we provide a comprehensive overview of the current state-of-the-art in the regulation of RNA-based products, addressing the challenges and opportunities for integrating these innovations into sustainable agricultural practices. As the regulatory landscape evolves, understanding the safety, efficacy, and environmental impact of ncRNA-based technologies will be crucial for their successful deployment. By leveraging the advances in plant science research, long and small ncRNAs hold promise for designing highly specific tools to boost crop productivity while preserving genetic diversity, contributing to global food security and sustainable agriculture.","PeriodicalId":501012,"journal":{"name":"The Plant Cell","volume":"92 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143635599","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}

引用次数: 0

The psbA ORF acts in cis to toggle HCF173 from an activator to a repressor for light-regulated psbA translation in plants psbA ORF 在植物光调 psbA 翻译中顺式作用于 HCF173，使其从激活剂变为抑制剂

The Plant Cell Pub Date : 2025-03-11 DOI: 10.1093/plcell/koaf047

Rosalind Williams-Carrier, Prakitchai Chotewutmontri, Sarah Perkel, Margarita Rojas, Susan Belcher, Alice Barkan

{"title":"The psbA ORF acts in cis to toggle HCF173 from an activator to a repressor for light-regulated psbA translation in plants","authors":"Rosalind Williams-Carrier, Prakitchai Chotewutmontri, Sarah Perkel, Margarita Rojas, Susan Belcher, Alice Barkan","doi":"10.1093/plcell/koaf047","DOIUrl":"https://doi.org/10.1093/plcell/koaf047","url":null,"abstract":"The D1 subunit of photosystem II is subject to photooxidative damage. Photodamaged D1 must be replaced with nascent D1 to maintain photosynthesis. In plant chloroplasts, D1 photodamage regulates D1 synthesis by modulating translation initiation on psbA mRNA encoding D1. The underlying mechanisms are unknown. Analyses of reporter constructs in transplastomic tobacco showed that the psbA translational activator HCF173 activates via a cis-element in the psbA 5'-UTR. However, the psbA UTRs are not sufficient to program light-regulated translation. Instead, the psbA open reading frame represses translation initiation in cis, and D1 photodamage relieves this repression. HCF173 remains bound to the psbA 5'-UTR in the dark and truncation of HCF173 prevents repression in the dark, implicating HCF173 as a mediator of repression. We propose a model that accounts for these and prior observations, which is informed by structures of the Complex I assembly factor CIA30/NDUFAF1. We posit that D1 photodamage relieves a repressive cotranslational interaction between nascent D1 and HCF173's CIA30 domain, that the photosystem II assembly factor HCF136 promotes this repressive interaction, and that these events toggle HCF173 between activating and repressive conformations on psbA mRNA. These findings elucidate a translational rheostat that optimizes photosynthesis in response to shifting light conditions.","PeriodicalId":501012,"journal":{"name":"The Plant Cell","volume":"5 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143607914","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}

引用次数: 0

Redox-inactive CC-type glutaredoxins interfere with TGA transcription factor–dependent repression of target promoters in roots

The Plant Cell Pub Date : 2025-03-07 DOI: 10.1093/plcell/koaf038

Corinna Thurow, Anja Maren Pelizaeus, Pascal Mrozek, Ben Moritz Hoßbach, Jelena Budimir, Kerstin Schmitt, Oliver Valerius, Gerhard Braus, Christiane Gatz

{"title":"Redox-inactive CC-type glutaredoxins interfere with TGA transcription factor–dependent repression of target promoters in roots","authors":"Corinna Thurow, Anja Maren Pelizaeus, Pascal Mrozek, Ben Moritz Hoßbach, Jelena Budimir, Kerstin Schmitt, Oliver Valerius, Gerhard Braus, Christiane Gatz","doi":"10.1093/plcell/koaf038","DOIUrl":"https://doi.org/10.1093/plcell/koaf038","url":null,"abstract":"Changes in nitrogen (N) availability in the soil trigger transcriptional responses in plants to optimize N acquisition, allocation, and remobilization. In roots of N-starved Arabidopsis (Arabidopsis thaliana) plants, transcriptional activation of genes encoding, for example, low-affinity nitrate transporters, depends on 4 related C-TERMINALLY ENCODED PEPTIDE DOWNSTREAM (CEPD) proteins, also known as ROXY6, ROXY7, ROXY8, and ROXY9. All 21 ROXYs found in A. thaliana interact with members of the TGACG-binding (TGA) family of transcription factors. Here, we demonstrate that 2 Clade I TGAs (TGA1, TGA4) serve as molecular links between CEPDs and their target promoters in roots. In the roxy6 roxy7 roxy8 roxy9 quadruple mutant (named cepd in this manuscript), transcriptional activation of N-starvation-inducible genes is impaired, most likely due to the association of Clade I TGAs with a repressive complex at their target promoters. In wild-type plants, this repressive complex is nonfunctional, and gene expression may be regulated by the N supply-regulated ratio of CEPDs over opposing ROXYs containing the TOPLESS-interacting ALWL motif. Although CEPDs resemble glutaredoxins with glutathione-dependent oxidoreductase activity, a ROXY9 variant with a mutation in the catalytic cysteine in its putative active site can confer wild-type-like regulation of target genes. This finding demonstrates that ROXY9 does not function through redox-dependent mechanisms.","PeriodicalId":501012,"journal":{"name":"The Plant Cell","volume":"39 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143575365","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}

引用次数: 0

Powdery mildew induces chloroplast storage lipid formation at the expense of host thylakoids to promote spore production

The Plant Cell Pub Date : 2025-03-05 DOI: 10.1093/plcell/koaf041

Hang Xue, Johan Jaenisch, Joelle Sasse, E Riley McGarrigle, Emma H Choi, Katherine Louie, Katharina Gutbrod, Peter Dörmann, Trent R Northen, Mary C Wildermuth

{"title":"Powdery mildew induces chloroplast storage lipid formation at the expense of host thylakoids to promote spore production","authors":"Hang Xue, Johan Jaenisch, Joelle Sasse, E Riley McGarrigle, Emma H Choi, Katherine Louie, Katharina Gutbrod, Peter Dörmann, Trent R Northen, Mary C Wildermuth","doi":"10.1093/plcell/koaf041","DOIUrl":"https://doi.org/10.1093/plcell/koaf041","url":null,"abstract":"Powdery mildews are obligate biotrophic fungi that manipulate plant metabolism to supply lipids to the fungus, particularly during fungal asexual reproduction when lipid demand is high. We found levels of leaf storage lipids (triacylglycerols, TAGs) are 3.5-fold higher in whole Arabidopsis (Arabidopsis thaliana) leaves with a 15-fold increase in storage lipids at the infection site during fungal asexual reproduction. Lipid bodies, not observable in uninfected mature leaves, were found in and external to chloroplasts in mesophyll cells underlying the fungal feeding structure. Concomitantly, thylakoid disassembly occurred and thylakoid membrane lipid levels decreased. Genetic analyses showed that canonical endoplasmic reticulum TAG biosynthesis does not support powdery mildew spore production. Instead, Arabidopsis chloroplast-localized DIACYLGLYCEROL ACYLTRANSFERASE 3 (DGAT3) promoted fungal asexual reproduction. Consistent with the reported AtDGAT3 preference for 18:3 and 18:2 acyl substrates, which are dominant in thylakoid membrane lipids, dgat3 mutants exhibited a dramatic reduction in powdery mildew-induced chloroplast TAGs, attributable to decreases in TAG species largely comprised of 18:3 and 18:2 acyl substrates. This pathway for TAG biosynthesis in the chloroplast at the expense of thylakoids provides insights into obligate biotrophy and plant lipid metabolism, plasticity and function. By understanding how photosynthetically active leaves can be converted into TAG producers, more sustainable and environmentally friendly plant oil production may be developed.","PeriodicalId":501012,"journal":{"name":"The Plant Cell","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143546241","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}

引用次数: 0

A family of α/β hydrolases removes phytol from chlorophyll metabolites for tocopherol biosynthesis in Arabidopsis

The Plant Cell Pub Date : 2025-03-04 DOI: 10.1093/plcell/koaf021

Yan Bao, Maria Magallanes-Lundback, Sung Soo Kim, Nicholas Deason, Yue Niu, Cassandra Johnny, John Froehlich, Dean DellaPenna

{"title":"A family of α/β hydrolases removes phytol from chlorophyll metabolites for tocopherol biosynthesis in Arabidopsis","authors":"Yan Bao, Maria Magallanes-Lundback, Sung Soo Kim, Nicholas Deason, Yue Niu, Cassandra Johnny, John Froehlich, Dean DellaPenna","doi":"10.1093/plcell/koaf021","DOIUrl":"https://doi.org/10.1093/plcell/koaf021","url":null,"abstract":"Tocopherol synthesis requires phytyl diphosphate derived from phytol esterified to chlorophyll metabolites. The &gt;600-member Arabidopsis thaliana α/β hydrolase (ABH) gene family contains 4 members that can release phytol from chlorophyll metabolites in vitro; however, only pheophytinase (PPH) affects tocopherol synthesis when mutated, reducing seed tocopherols by 5%. We report the biochemical analysis of 2 previously uncharacterized ABHs, chlorophyll dephytylase 2 (CLD2) and CLD3, and their respective mutants singly and in combinations with pph and cld1 alleles. While all CLDs localized to the thylakoid and could hydrolyze phytol from chlorophylls and Pheophytin a in vitro, CLD3 had the highest in vitro activity and the largest effect on tocopherol synthesis in vivo. The 3 CLDs acted cooperatively to provide phytol for 31% of tocopherols synthesized in light-grown leaf tissue. Dark-induced leaf senescence assays showed PPH is required for 18% of the tocopherols synthesized. Though the cld123 triple mutant had no impact on dark-induced tocopherol content, cld123 in the pph background reduced tocopherol levels by an additional 18%. In seeds, pph and cld123 each reduced tocopherol content by 5% and by 15% in the cld123pph quadruple mutant. VTE7 (ViTamin E7) is an envelope-localized ABH that specifically affects chlorophyll biosynthetic intermediates in vivo and is required for 55% of seed tocopherol synthesis. The introduction of cld123pph into the vte7 background further reduced seed tocopherol levels to 23% of that of the wild type. Our findings demonstrate that phytol provision for tocopherol biosynthesis and homeostasis is a complex process involving the coordinated spatiotemporal expression of multiple ABH family members.","PeriodicalId":501012,"journal":{"name":"The Plant Cell","volume":"16 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143546242","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}

引用次数: 0

Tethering ferredoxin-NADP+ reductase to photosystem I promotes photosynthetic cyclic electron transfer

The Plant Cell Pub Date : 2025-03-04 DOI: 10.1093/plcell/koaf042

Thomas Z Emrich-Mills, Matthew S Proctor, Gustaf E Degen, Philip J Jackson, Katherine H Richardson, Frederick R Hawkings, Felix Buchert, Andrew Hitchcock, C Neil Hunter, Luke C M Mackinder, Michael Hippler, Matthew P Johnson

{"title":"Tethering ferredoxin-NADP+ reductase to photosystem I promotes photosynthetic cyclic electron transfer","authors":"Thomas Z Emrich-Mills, Matthew S Proctor, Gustaf E Degen, Philip J Jackson, Katherine H Richardson, Frederick R Hawkings, Felix Buchert, Andrew Hitchcock, C Neil Hunter, Luke C M Mackinder, Michael Hippler, Matthew P Johnson","doi":"10.1093/plcell/koaf042","DOIUrl":"https://doi.org/10.1093/plcell/koaf042","url":null,"abstract":"Fixing CO2 via photosynthesis requires ATP and NADPH, which can be generated through linear electron transfer (LET). However, depending on the environmental conditions, additional ATP may be required to fix CO2, which can be generated by cyclic electron transfer (CET). How the balance between LET and CET is determined remains largely unknown. Ferredoxin-NADP+ reductase (FNR) may act as the switch between LET and CET, channelling photosynthetic electrons to LET when it is bound to photosystem I (PSI) or to CET when it is bound to cytochrome b6f. The essential role of FNR in LET precludes the use of a direct gene knock-out to test this hypothesis. Nevertheless, we circumvented this problem using clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated nuclease 9 (Cas9)-mediated gene editing in Chlamydomonas reinhardtii. Through this approach, we created a chimeric form of FNR tethered to PSI via PSAF. Chimeric FNR mutants exhibited impaired photosynthetic growth and LET along with enhanced PSI acceptor side limitation relative to the wild type due to slower NADPH reduction. However, the chimeric FNR mutants also showed enhanced ΔpH production and NPQ resulting from increased CET. Overall, our results suggest that rather than promoting LET, tethering FNR to PSI promotes CET at the expense of LET and CO2 fixation.","PeriodicalId":501012,"journal":{"name":"The Plant Cell","volume":"13 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143546244","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}

引用次数: 0