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Lemke MD, Abate AN, Woodson JD. Investigating the mechanism of chloroplast singlet oxygen signaling in the Arabidopsis thaliana accelerated cell death 2 mutant. PLANT SIGNALING & BEHAVIOR 2024; 19:2347783. [PMID: 38699898 PMCID: PMC11073415 DOI: 10.1080/15592324.2024.2347783] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2024] [Accepted: 04/19/2024] [Indexed: 05/05/2024]
Abstract
As sessile organisms, plants have evolved complex signaling mechanisms to sense stress and acclimate. This includes the use of reactive oxygen species (ROS) generated during dysfunctional photosynthesis to initiate signaling. One such ROS, singlet oxygen (1O2), can trigger retrograde signaling, chloroplast degradation, and programmed cell death. However, the signaling mechanisms are largely unknown. Several proteins (e.g. PUB4, OXI1, EX1) are proposed to play signaling roles across three Arabidopsis thaliana mutants that conditionally accumulate chloroplast 1O2 (fluorescent in blue light (flu), chlorina 1 (ch1), and plastid ferrochelatase 2 (fc2)). We previously demonstrated that these mutants reveal at least two chloroplast 1O2 signaling pathways (represented by flu and fc2/ch1). Here, we test if the 1O2-accumulating lesion mimic mutant, accelerated cell death 2 (acd2), also utilizes these pathways. The pub4-6 allele delayed lesion formation in acd2 and restored photosynthetic efficiency and biomass. Conversely, an oxi1 mutation had no measurable effect on these phenotypes. acd2 mutants were not sensitive to excess light (EL) stress, yet pub4-6 and oxi1 both conferred EL tolerance within the acd2 background, suggesting that EL-induced 1O2 signaling pathways are independent from spontaneous lesion formation. Thus, 1O2 signaling in acd2 may represent a third (partially overlapping) pathway to control cellular degradation.
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Affiliation(s)
- Matthew D. Lemke
- The School of Plant Sciences, University of Arizona, Tucson, AZ, USA
| | - Alexa N. Abate
- The School of Plant Sciences, University of Arizona, Tucson, AZ, USA
| | - Jesse D. Woodson
- The School of Plant Sciences, University of Arizona, Tucson, AZ, USA
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2
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Rai S, Lemke MD, Arias AM, Mendez MFG, Dehesh K, Woodson JD. Plant U-Box 4 regulates chloroplast stress signaling and programmed cell death via Salicylic acid modulation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.13.593788. [PMID: 38798329 PMCID: PMC11118471 DOI: 10.1101/2024.05.13.593788] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2024]
Abstract
In response to environmental stress, chloroplasts generate reactive oxygen species, including singlet oxygen (1O2), which regulates nuclear gene expression (retrograde signaling), chloroplast turnover, and programmed cell death (PCD). Yet, the central signaling mechanisms and downstream responses remain poorly understood. The Arabidopsis thaliana plastid ferrochelatase two (fc2) mutant conditionally accumulates 1O2 and involves Plant U-Box 4 (PUB4), a cytoplasmic E3 ubiquitin ligase, in propagating these signals. To gain insights into 1O2 signaling pathways, we compared transcriptomes of fc2 and fc2 pub4 mutants. The accumulation of 1O2 in fc2 plants broadly repressed genes involved in chloroplast function and photosynthesis, while 1O2 induced genes and transcription factors involved in abiotic and biotic stress, the biosynthesis of jasmonic acid (JA), and Salicylic acid (SA). Elevated JA and SA levels were observed in stressed fc2 plants, but were not responsible for PCD. pub4 reversed the majority of 1O2-induced gene expression in fc2 and reduced the JA content, but maintained elevated levels of SA even in the absence of 1O2 stress. Reducing SA levels in fc2 pub4 restored 1O2 signaling and light sensitivity. Together, this work demonstrates that SA plays a protective role during photo-oxidative stress and that PUB4 mediates 1O2 signaling by modulating its levels.
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Affiliation(s)
- Snigdha Rai
- The School of Plant Sciences, University of Arizona, Tucson, AZ
| | | | - Anika M. Arias
- The School of Plant Sciences, University of Arizona, Tucson, AZ
| | - Maria F. Gomez Mendez
- Department of Botany and Plant Sciences, Institute for Integrative Genome Biology, University of California, Riverside, CA
| | - Katayoon Dehesh
- Department of Botany and Plant Sciences, Institute for Integrative Genome Biology, University of California, Riverside, CA
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Mei Y, Hu T, Wang Y, Lozano-Durán R, Yang X, Zhou X. Two viral proteins translated from one open reading frame target different layers of plant defense. PLANT COMMUNICATIONS 2024; 5:100788. [PMID: 38160257 PMCID: PMC11009156 DOI: 10.1016/j.xplc.2023.100788] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2023] [Revised: 12/22/2023] [Accepted: 12/26/2023] [Indexed: 01/03/2024]
Abstract
Multilayered defense responses are activated upon pathogen attack. Viruses utilize a number of strategies to maximize the coding capacity of their small genomes and produce viral proteins for infection, including suppression of host defense. Here, we reveal translation leakage as one of these strategies: two viral effectors encoded by tomato golden mosaic virus, chloroplast-localized C4 (cC4) and membrane-associated C4 (mC4), are translated from two in-frame start codons and function cooperatively to suppress defense. cC4 localizes in chloroplasts, to which it recruits NbPUB4 to induce ubiquitination of the outer membrane; as a result, this organelle is degraded, and chloroplast-mediated defenses are abrogated. However, chloroplast-localized cC4 induces the production of singlet oxygen (1O2), which in turn promotes translocation of the 1O2 sensor NbMBS1 from the cytosol to the nucleus, where it activates expression of the CERK1 gene. Importantly, an antiviral effect exerted by CERK1 is countered by mC4, localized at the plasma membrane. mC4, like cC4, recruits NbPUB4 and promotes the ubiquitination and subsequent degradation of CERK1, suppressing membrane-based, receptor-like kinase-dependent defenses. Importantly, this translation leakage strategy seems to be conserved in multiple viral species and is related to host range. This finding suggests that stacking of different cellular antiviral responses could be an effective way to abrogate viral infection and engineer sustainable resistance to major crop viral diseases in the field.
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Affiliation(s)
- Yuzhen Mei
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, Zhejiang 310058, China; State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
| | - Tao Hu
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Yaqin Wang
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Rosa Lozano-Durán
- Department of Plant Biochemistry, Center for Plant Molecular Biology (ZMBP), Eberhard Karls University, 72076 Tübingen, Germany
| | - Xiuling Yang
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China.
| | - Xueping Zhou
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, Zhejiang 310058, China; State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China.
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Lemke MD, Woodson JD. A genetic screen for dominant chloroplast reactive oxygen species signaling mutants reveals life stage-specific singlet oxygen signaling networks. FRONTIERS IN PLANT SCIENCE 2024; 14:1331346. [PMID: 38273946 PMCID: PMC10809407 DOI: 10.3389/fpls.2023.1331346] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Accepted: 12/18/2023] [Indexed: 01/27/2024]
Abstract
Introduction Plants employ intricate molecular mechanisms to respond to abiotic stresses, which often lead to the accumulation of reactive oxygen species (ROS) within organelles such as chloroplasts. Such ROS can produce stress signals that regulate cellular response mechanisms. One ROS, singlet oxygen (1O2), is predominantly produced in the chloroplast during photosynthesis and can trigger chloroplast degradation, programmed cell death (PCD), and retrograde (organelle-to-nucleus) signaling. However, little is known about the molecular mechanisms involved in these signaling pathways or how many different signaling 1O2 pathways may exist. Methods The Arabidopsis thaliana plastid ferrochelatase two (fc2) mutant conditionally accumulates chloroplast 1O2, making fc2 a valuable genetic system for studying chloroplast 1O2-initiated signaling. Here, we have used activation tagging in a new forward genetic screen to identify eight dominant fc2 activation-tagged (fas) mutations that suppress chloroplast 1O2-initiated PCD. Results While 1O2-triggered PCD is blocked in all fc2 fas mutants in the adult stage, such cellular degradation in the seedling stage is blocked in only two mutants. This differential blocking of PCD suggests that life-stage-specific 1O2-response pathways exist. In addition to PCD, fas mutations generally reduce 1O2-induced retrograde signals. Furthermore, fas mutants have enhanced tolerance to excess light, a natural mechanism to produce chloroplast 1O2. However, general abiotic stress tolerance was only observed in one fc2 fas mutant (fc2 fas2). Together, this suggests that plants can employ general stress tolerance mechanisms to overcome 1O2 production but that this screen was mostly specific to 1O2 signaling. We also observed that salicylic acid (SA) and jasmonate (JA) stress hormone response marker genes were induced in 1O2-stressed fc2 and generally reduced by fas mutations, suggesting that SA and JA signaling is correlated with active 1O2 signaling and PCD. Discussion Together, this work highlights the complexity of 1O2 signaling by demonstrating that multiple pathways may exist and introduces a suite of new 1O2 signaling mutants to investigate the mechanisms controlling chloroplast-initiated degradation, PCD, and retrograde signaling.
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Affiliation(s)
| | - Jesse D. Woodson
- The School of Plant Sciences, University of Arizona, Tucson, AZ, United States
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Barros JAS, Cavalcanti JHF, Pimentel KG, Magen S, Soroka Y, Weiss S, Medeiros DB, Nunes-Nesi A, Fernie AR, Avin-Wittenberg T, Araújo WL. The interplay between autophagy and chloroplast vesiculation pathways under dark-induced senescence. PLANT, CELL & ENVIRONMENT 2023; 46:3721-3736. [PMID: 37615309 DOI: 10.1111/pce.14701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Revised: 07/14/2023] [Accepted: 08/15/2023] [Indexed: 08/25/2023]
Abstract
In cellular circumstances where carbohydrates are scarce, plants can use alternative substrates for cellular energetic maintenance. In plants, the main protein reserve is present in the chloroplast, which contains most of the total leaf proteins and represents a rich source of nitrogen and amino acids. Autophagy plays a key role in chloroplast breakdown, a well-recognised symptom of both natural and stress-induced plant senescence. Remarkably, an autophagic-independent route of chloroplast degradation associated with chloroplast vesiculation (CV) gene was previously demonstrated. During extended darkness, CV is highly induced in the absence of autophagy, contributing to the early senescence phenotype of atg mutants. To further investigate the role of CV under dark-induced senescence conditions, mutants with low expression of CV (amircv) and double mutants amircv1xatg5 were characterised. Following darkness treatment, no aberrant phenotypes were observed in amircv single mutants; however, amircv1xatg5 double mutants displayed early senescence and altered dismantling of chloroplast and membrane structures under these conditions. Metabolic characterisation revealed that the functional lack of both CV and autophagy leads to higher impairment of amino acid release and differential organic acid accumulation during starvation conditions. The data obtained are discussed in the context of the role of CV and autophagy, both in terms of cellular metabolism and the regulation of chloroplast degradation.
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Affiliation(s)
- Jessica A S Barros
- Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Viçosa, Minas Gerais, Brazil
| | - João Henrique F Cavalcanti
- Instituto de Educação, Agricultura e Ambiente, Universidade Federal do Amazonas, Humaitá, Amazonas, Brazil
| | - Karla G Pimentel
- Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Viçosa, Minas Gerais, Brazil
| | - Sahar Magen
- Department of Plant and Environmental Sciences, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Givat Ram, Jerusalem, Israel
| | - Yoram Soroka
- Department of Plant and Environmental Sciences, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Givat Ram, Jerusalem, Israel
| | - Shahar Weiss
- Department of Plant and Environmental Sciences, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Givat Ram, Jerusalem, Israel
| | - David B Medeiros
- Max Planck Institute of Molecular Plant Physiology, Potsdam, Germany
| | - Adriano Nunes-Nesi
- Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Viçosa, Minas Gerais, Brazil
| | - Alisdair R Fernie
- Max Planck Institute of Molecular Plant Physiology, Potsdam, Germany
| | - Tamar Avin-Wittenberg
- Department of Plant and Environmental Sciences, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Givat Ram, Jerusalem, Israel
| | - Wagner L Araújo
- Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Viçosa, Minas Gerais, Brazil
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Tadini L, Jeran N, Domingo G, Zambelli F, Masiero S, Calabritto A, Costantini E, Forlani S, Marsoni M, Briani F, Vannini C, Pesaresi P. Perturbation of protein homeostasis brings plastids at the crossroad between repair and dismantling. PLoS Genet 2023; 19:e1010344. [PMID: 37418499 PMCID: PMC10355426 DOI: 10.1371/journal.pgen.1010344] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Accepted: 05/09/2023] [Indexed: 07/09/2023] Open
Abstract
The chloroplast proteome is a dynamic mosaic of plastid- and nuclear-encoded proteins. Plastid protein homeostasis is maintained through the balance between de novo synthesis and proteolysis. Intracellular communication pathways, including the plastid-to-nucleus signalling and the protein homeostasis machinery, made of stromal chaperones and proteases, shape chloroplast proteome based on developmental and physiological needs. However, the maintenance of fully functional chloroplasts is costly and under specific stress conditions the degradation of damaged chloroplasts is essential to the maintenance of a healthy population of photosynthesising organelles while promoting nutrient redistribution to sink tissues. In this work, we have addressed this complex regulatory chloroplast-quality-control pathway by modulating the expression of two nuclear genes encoding plastid ribosomal proteins PRPS1 and PRPL4. By transcriptomics, proteomics and transmission electron microscopy analyses, we show that the increased expression of PRPS1 gene leads to chloroplast degradation and early flowering, as an escape strategy from stress. On the contrary, the overaccumulation of PRPL4 protein is kept under control by increasing the amount of plastid chaperones and components of the unfolded protein response (cpUPR) regulatory mechanism. This study advances our understanding of molecular mechanisms underlying chloroplast retrograde communication and provides new insight into cellular responses to impaired plastid protein homeostasis.
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Affiliation(s)
- Luca Tadini
- Dipartimento di Bioscienze, Università degli Studi di Milano, Milano, Italy
| | - Nicolaj Jeran
- Dipartimento di Bioscienze, Università degli Studi di Milano, Milano, Italy
| | - Guido Domingo
- Dipartimento di Biotecnologie e Scienze della Vita, Università degli Studi dell'Insubria, Varese, Italy
| | - Federico Zambelli
- Dipartimento di Bioscienze, Università degli Studi di Milano, Milano, Italy
| | - Simona Masiero
- Dipartimento di Bioscienze, Università degli Studi di Milano, Milano, Italy
| | - Anna Calabritto
- Dipartimento di Bioscienze, Università degli Studi di Milano, Milano, Italy
| | - Elena Costantini
- Dipartimento di Biotecnologie e Scienze della Vita, Università degli Studi dell'Insubria, Varese, Italy
| | - Sara Forlani
- Dipartimento di Bioscienze, Università degli Studi di Milano, Milano, Italy
| | - Milena Marsoni
- Dipartimento di Biotecnologie e Scienze della Vita, Università degli Studi dell'Insubria, Varese, Italy
| | - Federica Briani
- Dipartimento di Bioscienze, Università degli Studi di Milano, Milano, Italy
| | - Candida Vannini
- Dipartimento di Biotecnologie e Scienze della Vita, Università degli Studi dell'Insubria, Varese, Italy
| | - Paolo Pesaresi
- Dipartimento di Bioscienze, Università degli Studi di Milano, Milano, Italy
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Tano DW, Kozlowska MA, Easter RA, Woodson JD. Multiple pathways mediate chloroplast singlet oxygen stress signaling. PLANT MOLECULAR BIOLOGY 2023; 111:167-187. [PMID: 36266500 DOI: 10.1007/s11103-022-01319-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Accepted: 10/07/2022] [Indexed: 06/16/2023]
Abstract
Chloroplast singlet oxygen initiates multiple pathways to control chloroplast degradation, cell death, and nuclear gene expression. Chloroplasts can respond to stress and changes in the environment by producing reactive oxygen species (ROS). Aside from being cytotoxic, ROS also have signaling capabilities. For example, the ROS singlet oxygen (1O2) can initiate nuclear gene expression, chloroplast degradation, and cell death. To unveil the signaling mechanisms involved, researchers have used several 1O2-producing Arabidopsis thaliana mutants as genetic model systems, including plastid ferrochelatase two (fc2), fluorescent in blue light (flu), chlorina 1 (ch1), and accelerated cell death 2 (acd2). Here, we compare these 1O2-producing mutants to elucidate if they utilize one or more signaling pathways to control cell death and nuclear gene expression. Using publicly available transcriptomic data, we demonstrate fc2, flu, and ch1 share a core response to 1O2 accumulation, but maintain unique responses, potentially tailored to respond to their specific stresses. Subsequently, we used a genetic approach to determine if these mutants share 1O2 signaling pathways by testing the ability of genetic suppressors of one 1O2 producing mutant to suppress signaling in a different 1O2 producing mutant. Our genetic analyses revealed at least two different chloroplast 1O2 signaling pathways control cellular degradation: one specific to the flu mutant and one shared by fc2, ch1, and acd2 mutants, but with life-stage-specific (seedling vs. adult) features. Overall, this work reveals chloroplast stress signaling involving 1O2 is complex and may allow cells to finely tune their physiology to environmental inputs.
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Affiliation(s)
- David W Tano
- The School of Plant Sciences, University of Arizona, 1140 E, South Campus Drive, 303 Forbes Hall, Tucson, AZ, 85721-0036, USA
| | - Marta A Kozlowska
- The School of Plant Sciences, University of Arizona, 1140 E, South Campus Drive, 303 Forbes Hall, Tucson, AZ, 85721-0036, USA
| | - Robert A Easter
- The School of Plant Sciences, University of Arizona, 1140 E, South Campus Drive, 303 Forbes Hall, Tucson, AZ, 85721-0036, USA
| | - Jesse D Woodson
- The School of Plant Sciences, University of Arizona, 1140 E, South Campus Drive, 303 Forbes Hall, Tucson, AZ, 85721-0036, USA.
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Su W, Wu Y, Zheng H, Guo X, Feng B, Guo F. miR-141-Modified Bone Marrow Mesenchymal Stem Cells (BMSCs) Inhibits the Progression of Severe Acute Pancreatitis. J BIOMATER TISS ENG 2023. [DOI: 10.1166/jbt.2023.3190] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The therapeutic effects of bone marrow mesenchymal stem cells (BMSCs) on severe acute pancreatitis (SAP) and miRNAs are currently the research hotspots. This study intends to explore the potential impact of miR-141-modified BMSCs on SAP. After establishment of rat model of SAP, the
animals were grouped into control group, model group, BMSCs group, miR-141 group, positive control group, and PI3K/mTOR signaling agonist group (agonist group) followed by analysis of miR-141 expression by RT-qPCR and the expression of serum amylase, IL-6, TNF-α, TAP, PI3K, mTOR,
and LC3-II by Western blot and ELISA. miR-141 was significantly up-regulated in the miR-141-modified BMSCs group (p > 0.05). The contents of serum amylase, IL-6, TNF-α, and TAP was increased in SAP rats and decreased after BMSC treatment (p > 0.05). The increased
autophagy flux in the rats with SAT was reduced upon treatment with BMSCs and autophagy flux was decreased in miR-141 group but increased in positive control group. The model and positive control group presented highest expression of LC3-II, p-PI3K and p-mTOR, followed by BMSCs group and miR-141
group (p < 0.05). In conclusion, miR-141-modified BMSCs decrease the phosphorylation of PI3K and mTOR to inhibit PI3K/mTOR signaling activity and downregulate LC3-II protein to inhibit autophagy, thereby ameliorating the development of SAP, indicating that miR-141 might be a therapeutic
target for SAP.
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Affiliation(s)
- Wei Su
- Department of Critical Care Medicine, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou 310016, Zhejiang, China
| | - Yinshan Wu
- Department of Critical Care Medicine, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou 310016, Zhejiang, China
| | - Huijun Zheng
- Department of Critical Care Medicine, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou 310016, Zhejiang, China
| | - Xiuliu Guo
- Department of Critical Care Medicine, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou 310016, Zhejiang, China
| | - Binbin Feng
- Department of Critical Care Medicine, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou 310016, Zhejiang, China
| | - Feng Guo
- Department of Critical Care Medicine, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou 310016, Zhejiang, China
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Lemke MD, Woodson JD. Targeted for destruction: degradation of singlet oxygen-damaged chloroplasts. PLANT SIGNALING & BEHAVIOR 2022; 17:2084955. [PMID: 35676885 PMCID: PMC9196835 DOI: 10.1080/15592324.2022.2084955] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/01/2022] [Revised: 05/26/2022] [Accepted: 05/29/2022] [Indexed: 06/15/2023]
Abstract
Photosynthesis is an essential process that plants must regulate to survive in dynamic environments. Thus, chloroplasts (the sites of photosynthesis in plant and algae cells) use multiple signaling mechanisms to report their health to the cell. Such signals are poorly understood but often involve reactive oxygen species (ROS) produced from the photosynthetic light reactions. One ROS, singlet oxygen (1O2), can signal to initiate chloroplast degradation, but the cellular machinery involved in identifying and degrading damaged chloroplasts (i.e., chloroplast quality control pathways) is unknown. To provide mechanistic insight into these pathways, two recent studies have investigated degrading chloroplasts in the Arabidopsis thaliana1O2 over-producing plastid ferrochelatase two (fc2) mutant. First, a structural analysis of degrading chloroplasts was performed with electron microscopy, which demonstrated that damaged chloroplasts can protrude into the central vacuole compartment with structures reminiscent of fission-type microautophagy. 1O2-stressed chloroplasts swelled before these interactions, which may be a mechanism for their selective degradation. Second, the roles of autophagosomes and canonical autophagy (macroautophagy) were shown to be dispensable for 1O2-initiated chloroplast degradation. Instead, putative fission-type microautophagy genes were induced by chloroplast 1O2. Here, we discuss how these studies implicate this poorly understood cellular degradation pathway in the dismantling of 1O2-damaged chloroplasts.
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Affiliation(s)
- Matthew D. Lemke
- The School of Plant Sciences, University of Arizona, Tucson, AZ, USA
| | - Jesse D. Woodson
- The School of Plant Sciences, University of Arizona, Tucson, AZ, USA
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10
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Sharma I, Kirti PB, Pati PK. Autophagy: a game changer for plant development and crop improvement. PLANTA 2022; 256:103. [PMID: 36307739 DOI: 10.1007/s00425-022-04004-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Accepted: 09/21/2022] [Indexed: 06/16/2023]
Abstract
Manipulation of autophagic pathway represents a tremendous opportunity for designing climate-smart crops with improved yield and better adaptability to changing environment. For exploiting autophagy to its full potential, identification and comprehensive characterization of adapters/receptor complex and elucidation of its regulatory network in crop plants is highly warranted. Autophagy is a major intracellular trafficking pathway in eukaryotes involved in vacuolar degradation of cytoplasmic constituents, mis-folded proteins, and defective organelles. Under optimum conditions, autophagy operates at a basal level to maintain cellular homeostasis, but under stressed conditions, it is induced further to provide temporal stress relief. Our understanding of this highly dynamic process has evolved exponentially in the past few years with special reference to several plant-specific roles of autophagy. Here, we review the most recent advances in the field of autophagy in plants and discuss its potential implications in designing crops with improved stress and disease-tolerance, enhanced yield potential, and improved capabilities for producing metabolites of high economic value. We also assess the current knowledge gaps and the possible strategies to develop a robust module for biotechnological application of autophagy to enhance bioeconomy and sustainability of agriculture.
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Affiliation(s)
- Isha Sharma
- AgriBiotech Foundation, PJTS Agriculture University, Rajendranagar, Hyderabad, Telangana, 500032, India.
- International Crops Research Institute for the Semi-Arid Tropics, 502324, Patancheru, Telangana, India.
| | | | - Pratap Kumar Pati
- Department of Biotechnology, Guru Nanak Dev University, Amritsar, Punjab, 140301, India
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11
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Li C, Hu F, Chen H, Zhao J. Transcriptome characteristics during cell wall formation of endosperm cellularization and embryo differentiation in Arabidopsis. FRONTIERS IN PLANT SCIENCE 2022; 13:998664. [PMID: 36262665 PMCID: PMC9575994 DOI: 10.3389/fpls.2022.998664] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/20/2022] [Accepted: 09/16/2022] [Indexed: 06/16/2023]
Abstract
Embryonic and endosperm development are important biological events during Arabidopsis seed development, and are controlled by dynamic changes in a range of gene expression. Nevertheless, the regulatory mechanisms of endosperm cellularization and embryo differentiation remain unclear. Here, we characterized the early embryo and endosperm development of the naa15 mutant that had abnormal embryo differentiation and incomplete endosperm cellularization compared to WT of Arabidopsis, and comparatively investigated the changes of gene expressions in WT seeds at 3, 4, and 5 days after pollination (3W, 4W, and 5W) and the white homozygous aborted naa15 seeds at 5, 6, and 7 DAP (5M, 6M, and 7M) from naa15-1/+ siliques using RNA sequencing and qPCR assays. The transcriptome analyses showed that there were 2040 and 3630 differentially expressed genes (DEGs) in 4W (at endosperm cellularization initiation stage and heart embryo stage) vs 3W (at syncytium stage and globular embryo stage), and 5W (at end of endosperm cellularization stage and torpedo embryo stage) vs 4W, respectively. The KEGG and GO analyses showed that lipid metabolic processes and transmembrane transport related to cell wall biogenesis, cell division and differentiation, the plant hormone signaling pathway, photosynthesis, and transcription regulator activity were evidently enriched in WT and naa15. The heatmap and qPCR analyses showed that auxin response genes (ARFs), auxin transport genes (PINs) cytokinin synthesis genes (LOGs), cytokinin dehydrogenase genes (CKXs), cytokinin receptor, transcription factors (MYB, bHLH, MADS-box, and ERF) were significantly downregulated in naa15 compared to WT. A series of cell wall genes annotated to xyloglucan endotransglycosylase/hydrolase, pectin methyl esterase, and pectin methyl esterase inhibitor were also identified in these DEGs. Moreover, using an immunofluorescent assay, the features of cell walls displayed that cellulose fluorescence signals in the embryo and endosperm of naa15 were significantly decreased, and the signals of low- and high- methyl esterification of pectin were also obviously decreased in the endosperm of naa15. In summary, we identified a large number of DEGs and investigated the features of cell walls during endosperm cellularization and embryonic differentiation, which provided important information on transcription and gene expression to reveal their regulatory mechanisms.
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12
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Woodson JD. Control of chloroplast degradation and cell death in response to stress. Trends Biochem Sci 2022; 47:851-864. [DOI: 10.1016/j.tibs.2022.03.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Revised: 02/25/2022] [Accepted: 03/14/2022] [Indexed: 12/16/2022]
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Fisher KE, Krishnamoorthy P, Joens MS, Chory J, Fitzpatrick JAJ, Woodson JD. Singlet Oxygen Leads to Structural Changes to Chloroplasts during their Degradation in the Arabidopsis thaliana plastid ferrochelatase two Mutant. PLANT & CELL PHYSIOLOGY 2022; 63:248-264. [PMID: 34850209 DOI: 10.1093/pcp/pcab167] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Revised: 11/01/2021] [Accepted: 11/22/2021] [Indexed: 06/13/2023]
Abstract
During stress, chloroplasts produce large amounts of reactive oxygen species (ROS). Chloroplasts also contain many nutrients, including 80% of a leaf's nitrogen supply. Therefore, to protect cells from photo-oxidative damage and to redistribute nutrients to sink tissues, chloroplasts are prime targets for degradation. Multiple chloroplast degradation pathways are induced by photo-oxidative stress or nutrient starvation, but the mechanisms by which damaged or senescing chloroplasts are identified, transported to the central vacuole and degraded are poorly defined. Here, we investigated the structures involved with degrading chloroplasts induced by the ROS singlet oxygen (1O2) in the Arabidopsis thaliana plastid ferrochelatase two (fc2) mutant. Under mild 1O2 stress, most fc2 chloroplasts appeared normal, but had reduced starch content. A subset of chloroplasts was degrading, and some protruded into the central vacuole via 'blebbing' structures. A 3D electron microscopy analysis demonstrated that up to 35% of degrading chloroplasts contained such structures. While the location of a chloroplast within a cell did not affect the likelihood of its degradation, chloroplasts in spongy mesophyll cells were degraded at a higher rate than those in palisade mesophyll cells. To determine if degrading chloroplasts have unique structural characteristics, allowing them to be distinguished from healthy chloroplasts, we analyzed fc2 seedlings grown under different levels of photo-oxidative stress. A correlation was observed among chloroplast swelling, 1O2 signaling and the state of degradation. Finally, plastoglobule (PG) enzymes involved in chloroplast disassembly were upregulated while PGs increased their association with the thylakoid grana, implicating an interaction between 1O2-induced chloroplast degradation and senescence pathways.
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Affiliation(s)
- Karen E Fisher
- The School of Plant Sciences, University of Arizona, 1140 E South Campus Dr., Tucson, AZ 85721, USA
| | - Praveen Krishnamoorthy
- Washington University Center for Cellular Imaging, Washington University School of Medicine, 660 W. Euclid Avenue, St. Louis, MO 63110, USA
| | | | - Joanne Chory
- Plant Biology Laboratory and the Howard Hughes Medical Institute, The Salk Institute, 10010 N Torrey Pines Rd., La Jolla, CA 92037, USA
| | - James A J Fitzpatrick
- Washington University Center for Cellular Imaging, Washington University School of Medicine, 660 W. Euclid Avenue, St. Louis, MO 63110, USA
- Departments of Cell Biology & Physiology and Neuroscience, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, MO 63110, USA
- Department of Biomedical Engineering, Washington University in St. Louis, 1 Brookings Drive, St. Louis, MO 63130, USA
| | - Jesse D Woodson
- The School of Plant Sciences, University of Arizona, 1140 E South Campus Dr., Tucson, AZ 85721, USA
- Washington University Center for Cellular Imaging, Washington University School of Medicine, 660 W. Euclid Avenue, St. Louis, MO 63110, USA
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Soriano G, Kneeshaw S, Jimenez-Aleman G, Zamarreño ÁM, Franco-Zorrilla JM, Rey-Stolle MF, Barbas C, García-Mina JM, Solano R. An evolutionarily ancient fatty acid desaturase is required for the synthesis of hexadecatrienoic acid, which is the main source of the bioactive jasmonate in Marchantia polymorpha. THE NEW PHYTOLOGIST 2022; 233:1401-1413. [PMID: 34846752 DOI: 10.1111/nph.17850] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2021] [Accepted: 11/02/2021] [Indexed: 06/13/2023]
Abstract
Jasmonates are fatty acid-derived hormones that regulate multiple aspects of plant development, growth and stress responses. Bioactive jasmonates, defined as the ligands of the conserved COI1 receptor, differ between vascular plants and bryophytes (jasmonoyl-l-isoleucine (JA-Ile) and dinor-12-oxo-10,15(Z)-phytodienoic acid (dn-OPDA), respectively). The biosynthetic pathways of JA-Ile in the model vascular plant Arabidopsis thaliana have been elucidated. However, the details of dn-OPDA biosynthesis in bryophytes are still unclear. Here, we identify an orthologue of Arabidopsis fatty-acid-desaturase 5 (AtFAD5) in the model liverwort Marchantia polymorpha and show that FAD5 function is ancient and conserved between species separated by more than 450 million years (Myr) of independent evolution. Similar to AtFAD5, MpFAD5 is required for the synthesis of 7Z-hexadecenoic acid. Consequently, in Mpfad5 mutants, the hexadecanoid pathway is blocked, dn-OPDA concentrations are almost completely depleted and normal chloroplast development is impaired. Our results demonstrate that the main source of wounding-induced dn-OPDA in Marchantia is the hexadecanoid pathway and the contribution of the octadecanoid pathway (i.e. from OPDA) is minimal. Remarkably, despite extremely low concentrations of dn-OPDA, MpCOI1-mediated responses to wounding and insect feeding can still be activated in Mpfad5, suggesting that dn-OPDA may not be the only bioactive jasmonate and COI1 ligand in Marchantia.
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Affiliation(s)
- Gonzalo Soriano
- Department of Plant Molecular Genetics, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas (CNB-CSIC), Madrid, 28049, Spain
- Facultad de Ciencia y Tecnología, Universidad de La Rioja, Madre de Dios 53, Logroño (La Rioja), 26006, Spain
| | - Sophie Kneeshaw
- Department of Plant Molecular Genetics, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas (CNB-CSIC), Madrid, 28049, Spain
| | - Guillermo Jimenez-Aleman
- Department of Plant Molecular Genetics, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas (CNB-CSIC), Madrid, 28049, Spain
| | - Ángel M Zamarreño
- Department of Environmental Biology, University of Navarra, Navarra, 31008, Spain
| | - José Manuel Franco-Zorrilla
- Department of Plant Molecular Genetics, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas (CNB-CSIC), Madrid, 28049, Spain
| | - Mª Fernanda Rey-Stolle
- Centre for Metabolomics and Bioanalysis (CEMBIO), Chemistry and Biochemistry Department, Pharmacy Faculty, Universidad San Pablo-CEU, Boadilla del Monte, Madrid, 28668, Spain
| | - Coral Barbas
- Centre for Metabolomics and Bioanalysis (CEMBIO), Chemistry and Biochemistry Department, Pharmacy Faculty, Universidad San Pablo-CEU, Boadilla del Monte, Madrid, 28668, Spain
| | - Jose M García-Mina
- Department of Environmental Biology, University of Navarra, Navarra, 31008, Spain
| | - Roberto Solano
- Department of Plant Molecular Genetics, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas (CNB-CSIC), Madrid, 28049, Spain
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