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Yang J, Li B, Qin Y, Gao J, Zhang X, Yang X, Zhang G, Yan Y, Chen Y. Involvement of Programmed Cell Death and Autophagy on Schizogenous Secretory Canal Formation in Angelica dahurica var. formosana Root. Microsc Res Tech 2024. [PMID: 39400444 DOI: 10.1002/jemt.24711] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2024] [Revised: 08/30/2024] [Accepted: 09/26/2024] [Indexed: 10/15/2024]
Abstract
Schizogenous secretory canal is an important functional structure of Angelica dahurica var. formosana, which is the main part of the accumulation of essential oil, coumarin and other components. The developmental process of secretory tissue and the accumulation of components are closely related. Meanwhile, programmed cell death (PCD) plays an important role in the development of plant secretory tissues, which is usually associated with autophagy. However, there are fewer studies involving PCD and autophagy with the development of schizogenous secretory canal. This study aims to provide new data on the development of schizogenous secretory canal in A. dahurica var. formosana. Light and transmission electron microscopy were used to reveal the cytological characteristics of secretory canal in A. dahurica var. formosana roots at different developmental stages. PCD and autophagy signals during the developmental process were detected using techniques such as terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) detection, propidium iodide (PI) staining, and immunofluorescent labeling. The results showed that the walls of secretory cells were intact during the development of schizogenous secretory canal in A. dahurica var. formosana roots. Mature secretory cells showed high vacuolization and accumulated a large number of essential oils. Meanwhile, we also observed significant ultrastructural features of PCD and autophagy during the developmental process. The signal detection results indicated that PCD and autophagy were jointly involved in the development of schizogenous secretory canal in A. dahurica var. formosana roots, and caspase-3-like protease may act as an upstream signal and participate in PCD.
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Affiliation(s)
- Jiahui Yang
- School of Pharmacy, Shaanxi University of Chinese Medicine, Xianyang, Shaanxi, China
- Shaanxi Qinling Application, Development and Engineering, Center of Chinese Herbal Medicine, Xianyang, Shaanxi, China
| | - Boyuan Li
- School of Pharmacy, Shaanxi University of Chinese Medicine, Xianyang, Shaanxi, China
- Shaanxi Qinling Application, Development and Engineering, Center of Chinese Herbal Medicine, Xianyang, Shaanxi, China
| | - Yue Qin
- School of Pharmacy, Shaanxi University of Chinese Medicine, Xianyang, Shaanxi, China
- Shaanxi Qinling Application, Development and Engineering, Center of Chinese Herbal Medicine, Xianyang, Shaanxi, China
| | - Jing Gao
- School of Pharmacy, Shaanxi University of Chinese Medicine, Xianyang, Shaanxi, China
- Shaanxi Qinling Application, Development and Engineering, Center of Chinese Herbal Medicine, Xianyang, Shaanxi, China
| | - Xiaofei Zhang
- School of Pharmacy, Shaanxi University of Chinese Medicine, Xianyang, Shaanxi, China
- Shaanxi Qinling Application, Development and Engineering, Center of Chinese Herbal Medicine, Xianyang, Shaanxi, China
- Shaanxi Province Innovation Team of Aromatic Traditional Chinese Medicine Industrialization Key Technology, Xianyang, Shaanxi, China
- Research Center of Traditional, Chinese Medicine Aromatic Industry, Shaanxi University Engineering, Xianyang, Shaanxi, China
| | - Xinjie Yang
- School of Pharmacy, Shaanxi University of Chinese Medicine, Xianyang, Shaanxi, China
- Shaanxi Qinling Application, Development and Engineering, Center of Chinese Herbal Medicine, Xianyang, Shaanxi, China
| | - Gang Zhang
- School of Pharmacy, Shaanxi University of Chinese Medicine, Xianyang, Shaanxi, China
- Shaanxi Qinling Application, Development and Engineering, Center of Chinese Herbal Medicine, Xianyang, Shaanxi, China
| | - Yonggang Yan
- School of Pharmacy, Shaanxi University of Chinese Medicine, Xianyang, Shaanxi, China
- Shaanxi Qinling Application, Development and Engineering, Center of Chinese Herbal Medicine, Xianyang, Shaanxi, China
| | - Ying Chen
- School of Pharmacy, Shaanxi University of Chinese Medicine, Xianyang, Shaanxi, China
- Shaanxi Qinling Application, Development and Engineering, Center of Chinese Herbal Medicine, Xianyang, Shaanxi, China
- Shaanxi Province Innovation Team of Aromatic Traditional Chinese Medicine Industrialization Key Technology, Xianyang, Shaanxi, China
- Research Center of Traditional, Chinese Medicine Aromatic Industry, Shaanxi University Engineering, Xianyang, Shaanxi, China
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Otegui MS, Steelheart C, Ma W, Ma J, Kang BH, De Medina Hernandez VS, Dagdas Y, Gao C, Goto-Yamada S, Oikawa K, Nishimura M. Vacuolar degradation of plant organelles. THE PLANT CELL 2024; 36:3036-3056. [PMID: 38657116 PMCID: PMC11371181 DOI: 10.1093/plcell/koae128] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2024] [Revised: 03/21/2024] [Accepted: 03/21/2024] [Indexed: 04/26/2024]
Abstract
Plants continuously remodel and degrade their organelles due to damage from their metabolic activities and environmental stressors, as well as an integral part of their cell differentiation programs. Whereas certain organelles use local hydrolytic enzymes for limited remodeling, most of the pathways that control the partial or complete dismantling of organelles rely on vacuolar degradation. Specifically, selective autophagic pathways play a crucial role in recognizing and sorting plant organelle cargo for vacuolar clearance, especially under cellular stress conditions induced by factors like heat, drought, and damaging light. In these short reviews, we discuss the mechanisms that control the vacuolar degradation of chloroplasts, mitochondria, endoplasmic reticulum, Golgi, and peroxisomes, with an emphasis on autophagy, recently discovered selective autophagy receptors for plant organelles, and crosstalk with other catabolic pathways.
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Affiliation(s)
- Marisa S Otegui
- Department of Botany and Center for Quantitative Cell Imaging, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Charlotte Steelheart
- Department of Botany and Center for Quantitative Cell Imaging, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Wenlong Ma
- School of Life Sciences, Centre for Cell and Developmental Biology and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
| | - Juncai Ma
- School of Life Sciences, Centre for Cell and Developmental Biology and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
| | - Byung-Ho Kang
- School of Life Sciences, Centre for Cell and Developmental Biology and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
| | | | - Yasin Dagdas
- Gregor Mendel Institute (GMI), Austrian Academy of Sciences, Vienna BioCenter (VBC), Vienna 1030, Austria
| | - Caiji Gao
- Guangdong Provincial Key Laboratory of Biotechnology for Plant Development, School of Life Sciences, South China Normal University, Guangzhou 510631, China
| | - Shino Goto-Yamada
- Malopolska Centre of Biotechnology, Jagiellonian University, Krakow 30-348, Poland
| | - Kazusato Oikawa
- Division of Symbiotic Systems, National Institute for Basic Biology, Okazaki 444-8585, Japan
| | - Mikio Nishimura
- Faculty of Science and Engineering, Konan University, Kobe 658-8501, Japan
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van Wijk KJ. Intra-chloroplast proteases: A holistic network view of chloroplast proteolysis. THE PLANT CELL 2024; 36:3116-3130. [PMID: 38884601 PMCID: PMC11371162 DOI: 10.1093/plcell/koae178] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2024] [Revised: 06/12/2024] [Accepted: 06/12/2024] [Indexed: 06/18/2024]
Abstract
Different proteases and peptidases are present within chloroplasts and nonphotosynthetic plastids to process precursor proteins and to degrade cleaved chloroplast transit peptides and damaged, misfolded, or otherwise unwanted proteins. Collectively, these proteases and peptidases form a proteolysis network, with complementary activities and hierarchies, and build-in redundancies. Furthermore, this network is distributed across the different intra-chloroplast compartments (lumen, thylakoid, stroma, envelope). The challenge is to determine the contributions of each peptidase (system) to this network in chloroplasts and nonphotosynthetic plastids. This will require an understanding of substrate recognition mechanisms, degrons, substrate, and product size limitations, as well as the capacity and degradation kinetics of each protease. Multiple extra-plastidial degradation pathways complement these intra-chloroplast proteases. This review summarizes our current understanding of these intra-chloroplast proteases in Arabidopsis and crop plants with an emphasis on considerations for building a qualitative and quantitative network view.
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Affiliation(s)
- Klaas J van Wijk
- Section of Plant Biology, School of Integrative Plant Sciences (SIPS), Cornell University, Ithaca, NY 14853, USA
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Kołodziejczyk I, Kaźmierczak A. Melatonin - This is important to know. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 919:170871. [PMID: 38340815 DOI: 10.1016/j.scitotenv.2024.170871] [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: 12/09/2023] [Revised: 02/07/2024] [Accepted: 02/07/2024] [Indexed: 02/12/2024]
Abstract
MEL (N-acetyl-5-methoxytryptamine) is a well-known natural compound that controls cellular processes in both plants and animals and is primarily found in plants as a neurohormone. Its roles have been described very broadly, from its antioxidant function related to the photoperiod and determination of seasonal rhythms to its role as a signalling molecule, imitating the action of plant hormones (or even being classified as a prohormone). MEL positively affects the yield and survival of plants by increasing their tolerance to unfavourable biotic and abiotic conditions, which makes MEL widely applicable in ecological farming as a stimulant of growth and development. Thus, it is called a phytobiostimulator. In this review, we discuss the genesis of MEL functions, the presence of MEL at the cellular level and its effects on gene expression and plant development, which can ensure the survival of plants under the conditions they encounter. Moreover, we consider the future application possibilities of MEL in agriculture.
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Affiliation(s)
- Izabela Kołodziejczyk
- Department of Geobotany and Plant Ecology, Institute of Ecology and Environmental Protection, University of Lodz, Lodz 90-236, Banacha 12/16, 90-237, Poland
| | - Andrzej Kaźmierczak
- Department of Cytophysiology, Institute of Experimental Biology Faculty of Biology and Environmental Protection, University of Łódź, Pomorska 141/143, 90-236 Łódź, Poland.
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Li Z, Liu J, Chen Y, Liang A, He W, Qin X, Qin K, Mu Z. Genome-Wide Identification of PYL/RCAR ABA Receptors and Functional Analysis of LbPYL10 in Heat Tolerance in Goji ( Lycium barbarum). PLANTS (BASEL, SWITZERLAND) 2024; 13:887. [PMID: 38592885 PMCID: PMC10975129 DOI: 10.3390/plants13060887] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2024] [Revised: 03/13/2024] [Accepted: 03/15/2024] [Indexed: 04/11/2024]
Abstract
The characterization of the PYL/RCAR ABA receptors in a great deal of plant species has dramatically advanced the study of ABA functions involved in key physiological processes. However, the genes in this family are still unclear in Lycium (Goji) plants, one of the well-known economically, medicinally, and ecologically valuable fruit crops. In the present work, 12 homologs of Arabidopsis PYL/RCAR ABA receptors were first identified and characterized from Lycium (L.) barbarum (LbPYLs). The quantitative real-time PCR (qRT-PCR) analysis showed that these genes had clear tissue-specific expression patterns, and most of them were transcribed in the root with the largest amount. Among the three subfamilies, while the Group I and Group III members were down-regulated by extraneous ABA, the Group II members were up-regulated. At 42 °C, most transcripts showed a rapid and violent up-regulation response to higher temperature, especially members of Group II. One of the genes in the Group II members, LbPYL10, was further functionally validated by virus-induced gene silencing (VIGS) technology. LbPYL10 positively regulates heat stress tolerance in L. barbarum by alleviating chlorophyll degradation, thus maintaining chlorophyll stability. Integrating the endogenous ABA level increase following heat stress, it may be concluded that LbPYL-mediated ABA signaling plays a vital role in the thermotolerance of L. barbarum plants. Our results highlight the strong potential of LbPYL genes in breeding genetically modified L. barbarum crops that acclimate to climate change.
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Affiliation(s)
- Zeyu Li
- College of Life Sciences, Northwest A&F University, Yangling 712100, China; (Z.L.); (J.L.); (Y.C.); (W.H.)
| | - Jiyao Liu
- College of Life Sciences, Northwest A&F University, Yangling 712100, China; (Z.L.); (J.L.); (Y.C.); (W.H.)
| | - Yan Chen
- College of Life Sciences, Northwest A&F University, Yangling 712100, China; (Z.L.); (J.L.); (Y.C.); (W.H.)
| | - Aihua Liang
- College of Life Sciences & Technology, Tarim University, Alaer 843300, China;
- State Key Laboratory Breeding Base for the Protection and Utilization of Biological Resources in Tarim Basin Co–Funded by Xinjiang Corps and the Ministry of Science and Technology, Alaer 843300, China
| | - Wei He
- College of Life Sciences, Northwest A&F University, Yangling 712100, China; (Z.L.); (J.L.); (Y.C.); (W.H.)
| | - Xiaoya Qin
- National Wolfberry Engineering Research Center, Ningxia Academy of Agriculture and Forestry Sciences, Yinchuan 750002, China;
| | - Ken Qin
- National Wolfberry Engineering Research Center, Ningxia Academy of Agriculture and Forestry Sciences, Yinchuan 750002, China;
| | - Zixin Mu
- College of Life Sciences & Technology, Tarim University, Alaer 843300, China;
- State Key Laboratory Breeding Base for the Protection and Utilization of Biological Resources in Tarim Basin Co–Funded by Xinjiang Corps and the Ministry of Science and Technology, Alaer 843300, China
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Yen CC, Hsu CM, Jiang PL, Jauh GY. Dynamic organelle changes and autophagic processes in lily pollen germination. BOTANICAL STUDIES 2024; 65:5. [PMID: 38273136 PMCID: PMC10811312 DOI: 10.1186/s40529-024-00410-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2023] [Accepted: 01/08/2024] [Indexed: 01/27/2024]
Abstract
Pollen germination is a crucial process in the life cycle of flowering plants, signifying the transition of quiescent pollen grains into active growth. This study delves into the dynamic changes within organelles and the pivotal role of autophagy during lily pollen germination. Initially, mature pollen grains harbor undifferentiated organelles, including amyloplasts, mitochondria, and the Golgi apparatus. However, germination unveils remarkable transformations, such as the redifferentiation of amyloplasts accompanied by starch granule accumulation. We investigate the self-sustained nature of amylogenesis during germination, shedding light on its association with osmotic pressure. Employing BODIPY 493/503 staining, we tracked lipid body distribution throughout pollen germination, both with or without autophagy inhibitors (3-MA, NEM). Typically, lipid bodies undergo polarized movement from pollen grains into elongating pollen tubes, a process crucial for directional growth. Inhibiting autophagy disrupted this essential lipid body redistribution, underscoring the interaction between autophagy and lipid body dynamics. Notably, the presence of tubular endoplasmic reticulum (ER)-like structures associated with developing amyloplasts and lipid bodies implies their participation in autophagy. Starch granules, lipid bodies, and membrane remnants observed within vacuoles further reinforce the involvement of autophagic processes. Among the autophagy inhibitors, particularly BFA, significantly impede germination and growth, thereby affecting Golgi morphology. Immunogold labeling substantiates the pivotal role of the ER in forming autophagosome-like compartments and protein localization. Our proposed speculative model of pollen germination encompasses proplastid differentiation and autophagosome formation. This study advances our understanding of organelle dynamics and autophagy during pollen germination, providing valuable insights into the realm of plant reproductive physiology.
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Affiliation(s)
- Chih-Chung Yen
- Institute of Plant and Microbial Biology, Academia Sinica, 11529, Taipei, Taiwan, ROC
| | - Chia-Mei Hsu
- Institute of Plant and Microbial Biology, Academia Sinica, 11529, Taipei, Taiwan, ROC
| | - Pei-Luen Jiang
- Department of Biotechnology, National Formosa University, Huwei Township, Yulin County, Taiwan.
| | - Guang-Yuh Jauh
- Institute of Plant and Microbial Biology, Academia Sinica, 11529, Taipei, Taiwan, ROC.
- Molecular and Biological Agricultural Sciences, International Graduate Program, National Chung-Hsing University, Academia Sinica, Taipei, Taiwan.
- Biotechnology Center, National Chung-Hsing University, Taichung, Taiwan.
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7
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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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Cadena-Ramos AI, De-la-Peña C. Picky eaters: selective autophagy in plant cells. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2024; 117:364-384. [PMID: 37864806 DOI: 10.1111/tpj.16508] [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: 07/14/2023] [Revised: 09/21/2023] [Accepted: 10/10/2023] [Indexed: 10/23/2023]
Abstract
Autophagy, a fundamental cellular process, plays a vital role in maintaining cellular homeostasis by degrading damaged or unnecessary components. While selective autophagy has been extensively studied in animal cells, its significance in plant cells has only recently gained attention. In this review, we delve into the intriguing realm selective autophagy in plants, with specific focus on its involvement in nutrient recycling, organelle turnover, and stress response. Moreover, recent studies have unveiled the interesting interplay between selective autophagy and epigenetic mechanisms in plants, elucidating the significance of epigenetic regulation in modulating autophagy-related gene expression and finely tuning the selective autophagy process in plants. By synthesizing existing knowledge, this review highlights the emerging field of selective autophagy in plant cells, emphasizing its pivotal role in maintaining nutrient homeostasis, facilitating cellular adaptation, and shedding light on the epigenetic regulation that governs these processes. Our comprehensive study provides the way for a deeper understanding of the dynamic control of cellular responses to nutrient availability and stress conditions, opening new avenues for future research in this field of autophagy in plant physiology.
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Affiliation(s)
- Alexis I Cadena-Ramos
- Unidad de Biotecnología, Centro de Investigación Científica de Yucatán, Calle 43 No. 130 x 32 y 34 Col. Chuburná de Hidalgo, 97205, Mérida, Yucatán, Mexico
| | - Clelia De-la-Peña
- Unidad de Biotecnología, Centro de Investigación Científica de Yucatán, Calle 43 No. 130 x 32 y 34 Col. Chuburná de Hidalgo, 97205, Mérida, Yucatán, Mexico
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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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Choi HS, Bjornson M, Liang J, Wang J, Ke H, Hur M, De Souza A, Kumar KS, Mortimer JC, Dehesh K. COG-imposed Golgi functional integrity determines the onset of dark-induced senescence. NATURE PLANTS 2023; 9:1890-1901. [PMID: 37884654 DOI: 10.1038/s41477-023-01545-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2023] [Accepted: 09/18/2023] [Indexed: 10/28/2023]
Abstract
Plant survival depends on dynamic stress-response pathways in changing environments. To uncover pathway components, we screened an ethyl methanesulfonate-mutagenized transgenic line containing a stress-inducible luciferase construct and isolated a constitutive expression mutant. The mutant is the result of an amino acid substitution in the seventh subunit of the hetero-octameric conserved oligomeric Golgi (COG) complex of Arabidopsis thaliana. Complementation studies verified the Golgi localization of cog7, and stress tests established accelerated dark-induced carbon deprivation/senescence of the mutant compared with wild-type plants. Multiomics and biochemical analyses revealed accelerated induction of protein ubiquitination and autophagy, and a counterintuitive increased protein N-glycosylation in senescencing cog7 relative to wild-type. A revertant screen using the overexpressor (FOX)-hunting system established partial, but notable rescue of cog7 phenotypes by COG5 overexpression, and conversely premature senescence in reduced COG5 expressing lines. These findings identify COG-imposed Golgi functional integrity as a main player in ensuring cellular survival under energy-limiting conditions.
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Affiliation(s)
- Hee-Seung Choi
- Institute for Integrative Genome Biology and Department of Botany and Plant Sciences, University of California, Riverside, CA, USA
| | - Marta Bjornson
- Department of Plant Sciences, University of California, Davis, CA, USA
| | - Jiubo Liang
- Institute for Integrative Genome Biology and Department of Botany and Plant Sciences, University of California, Riverside, CA, USA
| | - Jinzheng Wang
- Institute for Integrative Genome Biology and Department of Botany and Plant Sciences, University of California, Riverside, CA, USA
| | - Haiyan Ke
- Institute for Integrative Genome Biology and Department of Botany and Plant Sciences, University of California, Riverside, CA, USA
| | - Manhoi Hur
- Institute for Integrative Genome Biology and Department of Botany and Plant Sciences, University of California, Riverside, CA, USA
| | - Amancio De Souza
- Institute for Integrative Genome Biology and Department of Botany and Plant Sciences, University of California, Riverside, CA, USA
| | | | - Jenny C Mortimer
- Lawrence Berkeley National Lab, Joint BioEnergy Institute, Emeryville, CA, USA
- School of Agriculture Food and Wine & Waite Research Institute, University of Adelaide, Adelaide, South Australia, Australia
| | - Katayoon Dehesh
- Institute for Integrative Genome Biology and Department of Botany and Plant Sciences, University of California, Riverside, CA, USA.
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11
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Agbemafle W, Wong MM, Bassham DC. Transcriptional and post-translational regulation of plant autophagy. JOURNAL OF EXPERIMENTAL BOTANY 2023; 74:6006-6022. [PMID: 37358252 PMCID: PMC10575704 DOI: 10.1093/jxb/erad211] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Accepted: 06/09/2023] [Indexed: 06/27/2023]
Abstract
In response to changing environmental conditions, plants activate cellular responses to enable them to adapt. One such response is autophagy, in which cellular components, for example proteins and organelles, are delivered to the vacuole for degradation. Autophagy is activated by a wide range of conditions, and the regulatory pathways controlling this activation are now being elucidated. However, key aspects of how these factors may function together to properly modulate autophagy in response to specific internal or external signals are yet to be discovered. In this review we discuss mechanisms for regulation of autophagy in response to environmental stress and disruptions in cell homeostasis. These pathways include post-translational modification of proteins required for autophagy activation and progression, control of protein stability of the autophagy machinery, and transcriptional regulation, resulting in changes in transcription of genes involved in autophagy. In particular, we highlight potential connections between the roles of key regulators and explore gaps in research, the filling of which can further our understanding of the autophagy regulatory network in plants.
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Affiliation(s)
- William Agbemafle
- Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, IA, USA
| | - Min May Wong
- Department of Genetics, Development and Cell Biology, Iowa State University, Ames, IA, USA
| | - Diane C Bassham
- Department of Genetics, Development and Cell Biology, Iowa State University, Ames, IA, USA
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12
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Zhou X, Zhang Q, Zhao Y, Ding S, Yu GH. Integrated Multi-Omics Analyses Reveal That Autophagy-Mediated Cellular Metabolism Is Required for the Initiation of Pollen Germination. Int J Mol Sci 2023; 24:15014. [PMID: 37834462 PMCID: PMC10573924 DOI: 10.3390/ijms241915014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Revised: 09/25/2023] [Accepted: 09/30/2023] [Indexed: 10/15/2023] Open
Abstract
Autophagy is an evolutionarily conserved mechanism for degrading and recycling various cellular components, functioning in both normal development and stress conditions. This process is tightly regulated by a set of autophagy-related (ATG) proteins, including ATG2 in the ATG9 cycling system and ATG5 in the ATG12 conjugation system. Our recent research demonstrated that autophagy-mediated compartmental cytoplasmic deletion is essential for pollen germination. However, the precise mechanisms through which autophagy regulates pollen germination, ensuring its fertility, remain largely unknown. Here, we applied multi-omics analyses, including transcriptomic and metabolomic approaches, to investigate the downstream pathways of autophagy in the process of pollen germination. Although ATG2 and ATG5 play similar roles in regulating pollen germination, high-throughput transcriptomic analysis reveals that silencing ATG5 has a greater impact on the transcriptome than silencing ATG2. Cross-comparisons of transcriptome and proteome analysis reveal that gene expression at the mRNA level and protein level is differentially affected by autophagy. Furthermore, high-throughput metabolomics analysis demonstrates that pathways related to amino acid metabolism and aminoacyl-tRNA biosynthesis were affected by both ATG2 and ATG5 silencing. Collectively, our multi-omics analyses reveal the central role of autophagy in cellular metabolism, which is critical for initiating pollen germination and ensuring pollen fertility.
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Affiliation(s)
| | | | | | | | - Guang-Hui Yu
- College of Life Sciences, South-Central Minzu University, Wuhan 430074, China; (X.Z.)
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13
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Wan C, Zhang H, Cheng H, Sowden RG, Cai W, Jarvis RP, Ling Q. Selective autophagy regulates chloroplast protein import and promotes plant stress tolerance. EMBO J 2023; 42:e112534. [PMID: 37248861 PMCID: PMC10350842 DOI: 10.15252/embj.2022112534] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2022] [Revised: 03/26/2023] [Accepted: 05/09/2023] [Indexed: 05/31/2023] Open
Abstract
Chloroplasts are plant organelles responsible for photosynthesis and environmental sensing. Most chloroplast proteins are imported from the cytosol through the translocon at the outer envelope membrane of chloroplasts (TOC). Previous work has shown that TOC components are regulated by the ubiquitin-proteasome system (UPS) to control the chloroplast proteome, which is crucial for the organelle's function and plant development. Here, we demonstrate that the TOC apparatus is also subject to K63-linked polyubiquitination and regulation by selective autophagy, potentially promoting plant stress tolerance. We identify NBR1 as a selective autophagy adaptor targeting TOC components, and mediating their relocation into vacuoles for autophagic degradation. Such selective autophagy is shown to control TOC protein levels and chloroplast protein import and to influence photosynthetic activity as well as tolerance to UV-B irradiation and heat stress in Arabidopsis plants. These findings uncover the vital role of selective autophagy in the proteolytic regulation of specific chloroplast proteins, and how dynamic control of chloroplast protein import is critically important for plants to cope with challenging environments.
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Affiliation(s)
- Chen Wan
- National Key Laboratory of Plant Molecular Genetics, CAS Centre for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and EcologyChinese Academy of SciencesShanghaiChina
- University of Chinese Academy of SciencesBeijingChina
| | - Hui Zhang
- National Key Laboratory of Plant Molecular Genetics, CAS Centre for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and EcologyChinese Academy of SciencesShanghaiChina
| | - Hongying Cheng
- National Key Laboratory of Plant Molecular Genetics, CAS Centre for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and EcologyChinese Academy of SciencesShanghaiChina
- University of Chinese Academy of SciencesBeijingChina
| | - Robert G Sowden
- Department of Plant Sciences and Section of Molecular Plant Biology (Department of Biology)University of OxfordOxfordUK
| | - Wenjuan Cai
- Core Facility Center, CAS Centre for Excellence in Molecular Plant SciencesChinese Academy of SciencesShanghaiChina
| | - R Paul Jarvis
- Department of Plant Sciences and Section of Molecular Plant Biology (Department of Biology)University of OxfordOxfordUK
| | - Qihua Ling
- National Key Laboratory of Plant Molecular Genetics, CAS Centre for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and EcologyChinese Academy of SciencesShanghaiChina
- University of Chinese Academy of SciencesBeijingChina
- CAS‐JIC Center of Excellence for Plant and Microbial Sciences (CEPAMS), Institute of Plant Physiology and EcologyChinese Academy of SciencesShanghaiChina
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14
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Rahman MA, Ullah H. Receptor for Activated C Kinase1B (RACK1B) Delays Salinity-Induced Senescence in Rice Leaves by Regulating Chlorophyll Degradation. PLANTS (BASEL, SWITZERLAND) 2023; 12:2385. [PMID: 37376011 DOI: 10.3390/plants12122385] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Revised: 06/17/2023] [Accepted: 06/19/2023] [Indexed: 06/29/2023]
Abstract
The widely conserved Receptor for Activated C Kinase1 (RACK1) protein is a WD-40 type scaffold protein that regulates diverse environmental stress signal transduction pathways. Arabidopsis RACK1A has been reported to interact with various proteins in salt stress and Light-Harvesting Complex (LHC) pathways. However, the mechanism of how RACK1 contributes to the photosystem and chlorophyll metabolism in stress conditions remains elusive. In this study, using T-DNA-mediated activation tagging transgenic rice (Oryza sativa L.) lines, we show that leaves from rice RACK1B gene (OsRACK1B) gain-of-function (RACK1B-OX) plants exhibit the stay-green phenotype under salinity stress. In contrast, leaves from down-regulated OsRACK1B (RACK1B-UX) plants display an accelerated yellowing. qRT-PCR analysis revealed that several genes which encode chlorophyll catabolic enzymes (CCEs) are differentially expressed in both RACK1B-OX and RACK1B-UX rice plants. In addition to CCEs, stay-green (SGR) is a key component that forms the SGR-CCE complex in senescing chloroplasts, and which causes LHCII complex instability. Transcript and protein profiling revealed a significant upregulation of OsSGR in RACK1B-UX plants compared to that in RACK1B-OX rice plants during salt treatment. The results imply that senescence-associated transcription factors (TFs) are altered following altered OsRACK1B expression, indicating a transcriptional reprogramming by OsRACK1B and a novel regulatory mechanism involving the OsRACK1B-OsSGR-TFs complex. Our findings suggest that the ectopic expression of OsRACK1B negatively regulates chlorophyll degradation, leads to a steady level of LHC-II isoform Lhcb1, an essential prerequisite for the state transition of photosynthesis for adaptation, and delays salinity-induced senescence. Taken together, these results provide important insights into the molecular mechanisms of salinity-induced senescence, which can be useful in circumventing the effect of salt on photosynthesis and in reducing the yield penalty of important cereal crops, such as rice, in global climate change conditions.
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Affiliation(s)
| | - Hemayet Ullah
- Department of Biology, Howard University, Washington, DC 20059, USA
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15
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Chiu CY, Lung HF, Chou WC, Lin LY, Chow HX, Kuo YH, Chien PS, Chiou TJ, Liu TY. Autophagy-Mediated Phosphate Homeostasis in Arabidopsis Involves Modulation of Phosphate Transporters. PLANT & CELL PHYSIOLOGY 2023; 64:519-535. [PMID: 36943363 DOI: 10.1093/pcp/pcad015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Revised: 01/31/2023] [Accepted: 03/01/2023] [Indexed: 05/17/2023]
Abstract
Autophagy in plants is regulated by diverse signaling cascades in response to environmental changes. Fine-tuning of its activity is critical for the maintenance of cellular homeostasis under basal and stressed conditions. In this study, we compared the Arabidopsis autophagy-related (ATG) system transcriptionally under inorganic phosphate (Pi) deficiency versus nitrogen deficiency and showed that most ATG genes are only moderately upregulated by Pi starvation, with relatively stronger induction of AtATG8f and AtATG8h among the AtATG8 family. We found that Pi shortage increased the formation of GFP-ATG8f-labeled autophagic structures and the autophagic flux in the differential zone of the Arabidopsis root. However, the proteolytic cleavage of GFP-ATG8f and the vacuolar degradation of endogenous ATG8 proteins indicated that Pi limitation does not drastically alter the autophagic flux in the whole roots, implying a cell type-dependent regulation of autophagic activities. At the organismal level, the Arabidopsis atg mutants exhibited decreased shoot Pi concentrations and smaller meristem sizes under Pi sufficiency. Under Pi limitation, these mutants showed enhanced Pi uptake and impaired root cell division and expansion. Despite a reduced steady-state level of several PHOSPHATE TRANSPORTER 1s (PHT1s) in the atg root, cycloheximide treatment analysis suggested that the protein stability of PHT1;1/2/3 is comparable in the Pi-replete wild type and atg5-1. By contrast, the degradation of PHT1;1/2/3 is enhanced in the Pi-deplete atg5-1. Our findings reveal that both basal autophagy and Pi starvation-induced autophagy are required for the maintenance of Pi homeostasis and may modulate the expression of PHT1s through different mechanisms.
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Affiliation(s)
- Chang-Yi Chiu
- Institute of Bioinformatics and Structural Biology, College of Life Science, National Tsing Hua University, No. 101, Sec. 2, Guangfu Rd., East Dist., Hsinchu 30013, Taiwan
| | - Hui-Fang Lung
- Institute of Bioinformatics and Structural Biology, College of Life Science, National Tsing Hua University, No. 101, Sec. 2, Guangfu Rd., East Dist., Hsinchu 30013, Taiwan
| | - Wen-Chun Chou
- Institute of Bioinformatics and Structural Biology, College of Life Science, National Tsing Hua University, No. 101, Sec. 2, Guangfu Rd., East Dist., Hsinchu 30013, Taiwan
| | - Li-Yen Lin
- Institute of Bioinformatics and Structural Biology, College of Life Science, National Tsing Hua University, No. 101, Sec. 2, Guangfu Rd., East Dist., Hsinchu 30013, Taiwan
| | - Hong-Xuan Chow
- Institute of Bioinformatics and Structural Biology, College of Life Science, National Tsing Hua University, No. 101, Sec. 2, Guangfu Rd., East Dist., Hsinchu 30013, Taiwan
| | - Yu-Hao Kuo
- Institute of Bioinformatics and Structural Biology, College of Life Science, National Tsing Hua University, No. 101, Sec. 2, Guangfu Rd., East Dist., Hsinchu 30013, Taiwan
| | - Pei-Shan Chien
- Agricultural Biotechnology Research Center, Academia Sinica, Taipei 11529, Taiwan
| | - Tzyy-Jen Chiou
- Agricultural Biotechnology Research Center, Academia Sinica, Taipei 11529, Taiwan
| | - Tzu-Yin Liu
- Institute of Bioinformatics and Structural Biology, College of Life Science, National Tsing Hua University, No. 101, Sec. 2, Guangfu Rd., East Dist., Hsinchu 30013, Taiwan
- Department of Life Science, College of Life Science, National Tsing Hua University, No. 101, Sec. 2, Guangfu Rd., East Dist., Hsinchu 30013, Taiwan
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16
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Cao B, Ge L, Zhang M, Li F, Zhou X. Geminiviral C2 proteins inhibit active autophagy to facilitate virus infection by impairing the interaction of ATG7 and ATG8. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2023; 65:1328-1343. [PMID: 36639894 DOI: 10.1111/jipb.13452] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Accepted: 01/13/2023] [Indexed: 05/13/2023]
Abstract
Autophagy is a conserved intracellular degradation process that plays an active role in plant response to virus infections. Here we report that geminiviruses counteract activated autophagy-mediated antiviral defense in plant cells through the C2 proteins they encode. We found that, in Nicotiana benthamiana plants, tomato leaf curl Yunnan virus (TLCYnV) infection upregulated the transcription levels of autophagy-related genes (ATGs). Overexpression of NbATG5, NbATG7, or NbATG8a in N. benthamiana plants decreased TLCYnV accumulation and attenuated viral symptoms. Interestingly, transgenic overexpression of NbATG7 promoted the growth of N. benthamiana plants and enhanced plant resistance to TLCYnV. We further revealed that the C2 protein encoded by TLCYnV directly interacted with the ubiquitin-activating domain of ATG7. This interaction competitively disrupted the ATG7-ATG8 binding in N. benthamiana and Solanum lycopersicum plants, thereby inhibiting autophagy activity. Furthermore, we uncovered that the C2-mediated autophagy inhibition mechanism was conserved in three other geminiviruses. In summary, we discovered a novel counter-defensive strategy employed by geminiviruses that enlists their C2 proteins as disrupters of ATG7-ATG8 interactions to defeat antiviral autophagy.
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Affiliation(s)
- Buwei Cao
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, 100193, China
| | - Linhao Ge
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, 100193, China
| | - Mingzhen Zhang
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, 100193, China
| | - Fangfang Li
- 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 for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, 100193, China
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, 310058, China
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17
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Kozuka T, Oka Y, Kohzuma K, Kusaba M. Cryptochromes suppress leaf senescence in response to blue light in Arabidopsis. PLANT PHYSIOLOGY 2023; 191:2506-2518. [PMID: 36715309 PMCID: PMC10069897 DOI: 10.1093/plphys/kiad042] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Accepted: 01/03/2023] [Indexed: 06/18/2023]
Abstract
The induction and progression of leaf senescence are effectively changed according to the light environment. The leaf senescence response is enhanced when plants are grown under a dense shade cast by neighboring vegetation. Although the fluence rate of the red and blue regions in the light spectrum is strongly attenuated under shade, photosensory mechanisms that underpin the blue light response are still unclear. In this study, we analyzed leaf senescence in response to blue light in Arabidopsis (Arabidopsis thaliana). We found that leaf senescence was promoted by the elimination of active phytochrome Pfr by pulsed far-red (FR) light, whereas irradiation with blue light suppressed leaf senescence in the wild type but not in the cryptochrome (CRY)-deficient mutant, cry1 cry2. Hence, two light-sensing modes contributed to the suppression of leaf senescence that was dependent on light spectrum features. First was the leaf senescence response to blue light, which was mediated exclusively by cryptochromes. Second was the phytochrome-mediated leaf senescence response to red/FR light. Physiological analysis of transgenic plants expressing green fluorescent protein (GFP)-tagged CRY2 revealed that photo-activation of cryptochromes was required to suppress leaf senescence in response to blue light. Transcriptomic analysis further uncovered the molecular and cellular processes involved in the regulation of leaf senescence downstream of cryptochromes. Furthermore, analysis of cryptochrome-downstream components indicated that ELONGATED HYPOCOTYL 5 (HY5) and PHYTOCHROME INTERACTING FACTOR (PIF) 4 and PIF5 were required for suppression and promotion of leaf senescence, respectively.
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Affiliation(s)
- Toshiaki Kozuka
- Graduate School of Integrated Science for Life, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526, Japan
| | - Yoshito Oka
- Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
| | - Kaori Kohzuma
- Graduate School of Integrated Science for Life, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526, Japan
| | - Makoto Kusaba
- Graduate School of Integrated Science for Life, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526, Japan
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18
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Jurado-Flores A, Gotor C, Romero LC. Proteome Dynamics of Persulfidation in Leaf Tissue under Light/Dark Conditions and Carbon Deprivation. Antioxidants (Basel) 2023; 12:antiox12040789. [PMID: 37107163 PMCID: PMC10135009 DOI: 10.3390/antiox12040789] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2023] [Revised: 03/09/2023] [Accepted: 03/21/2023] [Indexed: 04/29/2023] Open
Abstract
Hydrogen sulfide (H2S) acts as a signaling molecule in plants, bacteria, and mammals, regulating various physiological and pathological processes. The molecular mechanism by which hydrogen sulfide exerts its action involves the posttranslational modification of cysteine residues to form a persulfidated thiol motif. This research aimed to study the regulation of protein persulfidation. We used a label-free quantitative approach to measure the protein persulfidation profile in leaves under different growth conditions such as light regimen and carbon deprivation. The proteomic analysis identified a total of 4599 differentially persulfidated proteins, of which 1115 were differentially persulfidated between light and dark conditions. The 544 proteins that were more persulfidated in the dark were analyzed, and showed significant enrichment in functions and pathways related to protein folding and processing in the endoplasmic reticulum. Under light conditions, the persulfidation profile changed, and the number of differentially persulfidated proteins increased up to 913, with the proteasome and ubiquitin-dependent and ubiquitin-independent catabolic processes being the most-affected biological processes. Under carbon starvation conditions, a cluster of 1405 proteins was affected by a reduction in their persulfidation, being involved in metabolic processes that provide primary metabolites to essential energy pathways and including enzymes involved in sulfur assimilation and sulfide production.
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Affiliation(s)
- Ana Jurado-Flores
- Instituto de Bioquímica Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Científicas and Universidad de Sevilla, Avenida Américo Vespucio, 49, 41092 Sevilla, Spain
| | - Cecilia Gotor
- Instituto de Bioquímica Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Científicas and Universidad de Sevilla, Avenida Américo Vespucio, 49, 41092 Sevilla, Spain
| | - Luis C Romero
- Instituto de Bioquímica Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Científicas and Universidad de Sevilla, Avenida Américo Vespucio, 49, 41092 Sevilla, Spain
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19
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Sun Y, Li J, Zhang L, Lin R. Regulation of chloroplast protein degradation. J Genet Genomics 2023:S1673-8527(23)00049-8. [PMID: 36863685 DOI: 10.1016/j.jgg.2023.02.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2022] [Revised: 02/02/2023] [Accepted: 02/14/2023] [Indexed: 03/04/2023]
Abstract
Chloroplasts are unique organelles that not only provide sites for photosynthesis and many metabolic processes, but also are sensitive to various environmental stresses. Chloroplast proteins are encoded by genes from both nuclear and chloroplast genomes. During chloroplast development and responses to stresses, the robust protein quality control systems are essential for regulation of protein homeostasis and the integrity of chloroplast proteome. In this review, we summarize the regulatory mechanisms of chloroplast protein degradation refer to protease system, ubiquitin-proteasome system, and the chloroplast autophagy. These mechanisms symbiotically play a vital role in chloroplast development and photosynthesis under both normal or stress conditions.
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Affiliation(s)
- Yang Sun
- State Key Laboratory of Crop Stress Adaptation and Improvement, School of Life Sciences, Henan University, Kaifeng, Henan 475001, China
| | - Jialong Li
- Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Lixin Zhang
- State Key Laboratory of Crop Stress Adaptation and Improvement, School of Life Sciences, Henan University, Kaifeng, Henan 475001, China.
| | - Rongcheng Lin
- Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China.
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20
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Research progress on maintaining chloroplast homeostasis under stress conditions: a review. Acta Biochim Biophys Sin (Shanghai) 2023; 55:173-182. [PMID: 36840466 PMCID: PMC10157539 DOI: 10.3724/abbs.2023022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/18/2023] Open
Abstract
On a global scale, drought, salinity, extreme temperature, and other abiotic stressors severely limit the quality and yield of crops. Therefore, it is crucial to clarify the adaptation strategies of plants to harsh environments. Chloroplasts are important environmental sensors in plant cells. For plants to thrive in different habitats, chloroplast homeostasis must be strictly regulated, which is necessary to maintain efficient plant photosynthesis and other metabolic reactions under stressful environments. To maintain normal chloroplast physiology, two important biological processes are needed: the import and degradation of chloroplast proteins. The orderly import of chloroplast proteins and the timely degradation of damaged chloroplast components play a key role in adapting plants to their environment. In this review, we briefly described the mechanism of chloroplast TOC-TIC protein transport. The importance and recent progress of chloroplast protein turnover, retrograde signaling, and chloroplast protein degradation under stress are summarized. Furthermore, the potential of targeted regulation of chloroplast homeostasis is emphasized to improve plant adaptation to environmental stresses.
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21
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The role of Atg16 in autophagy, anthocyanin biosynthesis, and programmed cell death in leaves of the lace plant (Aponogeton madagascariensis). PLoS One 2023; 18:e0281668. [PMID: 36795694 PMCID: PMC9934333 DOI: 10.1371/journal.pone.0281668] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Accepted: 01/29/2023] [Indexed: 02/17/2023] Open
Abstract
Aponogeton madagascariensis, commonly known as the lace plant, produces leaves that form perforations by programmed cell death (PCD). Leaf development is divided into several stages beginning with "pre-perforation" furled leaves enriched with red pigmentation from anthocyanins. The leaf blade is characterized by a series of grids known as areoles bounded by veins. As leaves develop into the "window stage", anthocyanins recede from the center of the areole towards the vasculature creating a gradient of pigmentation and cell death. Cells in the middle of the areole that lack anthocyanins undergo PCD (PCD cells), while cells that retain anthocyanins (non-PCD cells) maintain homeostasis and persist in the mature leaf. Autophagy has reported roles in survival or PCD promotion across different plant cell types. However, the direct involvement of autophagy in PCD and anthocyanin levels during lace plant leaf development has not been determined. Previous RNA sequencing analysis revealed the upregulation of autophagy-related gene Atg16 transcripts in pre-perforation and window stage leaves, but how Atg16 affects PCD in lace plant leaf development is unknown. In this study, we investigated the levels of Atg16 in lace plant PCD by treating whole plants with either an autophagy promoter rapamycin or inhibitors concanamycin A (ConA) or wortmannin. Following treatments, window and mature stage leaves were harvested and analyzed using microscopy, spectrophotometry, and western blotting. Western blotting showed significantly higher Atg16 levels in rapamycin-treated window leaves, coupled with lower anthocyanin levels. Wortmannin-treated leaves had significantly lower Atg16 protein and higher anthocyanin levels compared to the control. Mature leaves from rapamycin-treated plants generated significantly fewer perforations compared to control, while wortmannin had the opposite effect. However, ConA treatment did not significantly change Atg16 levels, nor the number of perforations compared to the control, but anthocyanin levels did increase significantly in window leaves. We propose autophagy plays a dual role in promoting cell survival in NPCD cells by maintaining optimal anthocyanin levels and mediating a timely cell death in PCD cells in developing lace plant leaves. How autophagy specifically affects anthocyanin levels remained unexplained.
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22
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Norizuki T, Minamino N, Sato M, Ueda T. Autophagy regulates plastid reorganization during spermatogenesis in the liverwort Marchantia polymorpha. FRONTIERS IN PLANT SCIENCE 2023; 14:1101983. [PMID: 36844055 PMCID: PMC9947651 DOI: 10.3389/fpls.2023.1101983] [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: 11/18/2022] [Accepted: 01/23/2023] [Indexed: 06/18/2023]
Abstract
Autophagy is a highly conserved system that delivers cytoplasmic components to lysosomes/vacuoles. Plastids are also degraded through autophagy for nutrient recycling and quality control; however, the involvement of autophagic degradation of plastids in plant cellular differentiation remains unclear. Here, we investigated whether spermiogenesis, the differentiation of spermatids into spermatozoids, in the liverwort Marchantia polymorpha involves autophagic degradation of plastids. Spermatozoids of M. polymorpha possess one cylindrical plastid at the posterior end of the cell body. By fluorescently labeling and visualizing plastids, we detected dynamic morphological changes during spermiogenesis. We found that a portion of the plastid was degraded in the vacuole in an autophagy-dependent manner during spermiogenesis, and impaired autophagy resulted in defective morphological transformation and starch accumulation in the plastid. Furthermore, we found that autophagy was dispensable for the reduction in plastid number and plastid DNA elimination. These results demonstrate a critical but selective role of autophagy in plastid reorganization during spermiogenesis in M. polymorpha.
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Affiliation(s)
- Takuya Norizuki
- Division of Cellular Dynamics, National Institute for Basic Biology, Okazaki, Japan
- Laboratory of Molecular Membrane Biology, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Japan
| | - Naoki Minamino
- Division of Cellular Dynamics, National Institute for Basic Biology, Okazaki, Japan
| | - Miyuki Sato
- Laboratory of Molecular Membrane Biology, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Japan
| | - Takashi Ueda
- Division of Cellular Dynamics, National Institute for Basic Biology, Okazaki, Japan
- Department of Basic Biology, SOKENDAI (The Graduate University for Advanced Studies), Okazaki, Japan
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23
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Wang J, Zhang Q, Bao Y, Bassham D. Autophagic degradation of membrane-bound organelles in plants. Biosci Rep 2023; 43:BSR20221204. [PMID: 36562332 PMCID: PMC9842949 DOI: 10.1042/bsr20221204] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Revised: 12/19/2022] [Accepted: 12/22/2022] [Indexed: 12/24/2022] Open
Abstract
Eukaryotic cells have evolved membrane-bound organelles, including the endoplasmic reticulum (ER), Golgi, mitochondria, peroxisomes, chloroplasts (in plants and green algae) and lysosomes/vacuoles, for specialized functions. Organelle quality control and their proper interactions are crucial both for normal cell homeostasis and function and for environmental adaption. Dynamic turnover of organelles is tightly controlled, with autophagy playing an essential role. Autophagy is a programmed process for efficient clearing of unwanted or damaged macromolecules or organelles, transporting them to vacuoles for degradation and recycling and thereby enhancing plant environmental plasticity. The specific autophagic engulfment of organelles requires activation of a selective autophagy pathway, recognition of the organelle by a receptor, and selective incorporation of the organelle into autophagosomes. While some of the autophagy machinery and mechanisms for autophagic removal of organelles is conserved across eukaryotes, plants have also developed unique mechanisms and machinery for these pathways. In this review, we discuss recent progress in understanding autophagy regulation in plants, with a focus on autophagic degradation of membrane-bound organelles. We also raise some important outstanding questions to be addressed in the future.
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Affiliation(s)
- Jiaojiao Wang
- School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Qian Zhang
- School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Yan Bao
- School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Diane C. Bassham
- Department of Genetics, Development and Cell Biology, Iowa State University, Ames, IA 50011, U.S.A
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Su J, Gassmann W. Cytoplasmic regulation of chloroplast ROS accumulation during effector-triggered immunity. FRONTIERS IN PLANT SCIENCE 2023; 14:1127833. [PMID: 36794218 PMCID: PMC9922995 DOI: 10.3389/fpls.2023.1127833] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Accepted: 01/16/2023] [Indexed: 06/18/2023]
Abstract
Accumulating evidence suggests that chloroplasts are an important battleground during various microbe-host interactions. Plants have evolved layered strategies to reprogram chloroplasts to promote de novo biosynthesis of defense-related phytohormones and the accumulation of reactive oxygen species (ROS). In this minireview, we will discuss how the host controls chloroplast ROS accumulation during effector-triggered immunity (ETI) at the level of selective mRNA decay, translational regulation, and autophagy-dependent formation of Rubisco-containing bodies (RCBs). We hypothesize that regulation at the level of cytoplasmic mRNA decay impairs the repair cycle of photosystem II (PSII) and thus facilitates ROS generation at PSII. Meanwhile, removing Rubisco from chloroplasts potentially reduces both O2 and NADPH consumption. As a consequence, an over-reduced stroma would further exacerbate PSII excitation pressure and enhance ROS production at photosystem I.
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Yanagisawa M, Chuong SDX. Chloroplast Envelopes Play a Role in the Formation of Autophagy-Related Structures in Plants. PLANTS (BASEL, SWITZERLAND) 2023; 12:443. [PMID: 36771525 PMCID: PMC9920391 DOI: 10.3390/plants12030443] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/27/2022] [Revised: 01/12/2023] [Accepted: 01/16/2023] [Indexed: 06/18/2023]
Abstract
Autophagy is a degradation process of cytoplasmic components that is conserved in eukaryotes. One of the hallmark features of autophagy is the formation of double-membrane structures known as autophagosomes, which enclose cytoplasmic content destined for degradation. Although the membrane source for the formation of autophagosomes remains to be determined, recent studies indicate the involvement of various organelles in autophagosome biogenesis. In this study, we examined the autophagy process in Bienertia sinuspersici: one of four terrestrial plants capable of performing C4 photosynthesis in a single cell (single-cell C4 species). We demonstrated that narrow tubules (stromule-like structures) 30-50 nm in diameter appear to extend from chloroplasts to form the membrane-bound structures (autophagosomes or autophagy-related structures) in chlorenchyma cells of B. sinuspersici during senescence and under oxidative stress. Immunoelectron microscopic analysis revealed the localization of stromal proteins to the stromule-like structures, sequestering portions of the cytoplasm in chlorenchyma cells of oxidative stress-treated leaves of B. sinuspersici and Arabidopsis thaliana. Moreover, the fluorescent marker for autophagosomes GFP-ATG8, colocalized with the autophagic vacuole maker neutral red in punctate structures in close proximity to the chloroplasts of cells under oxidative stress conditions. Together our results implicate a role for chloroplast envelopes in the autophagy process induced during senescence or under certain stress conditions in plants.
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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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27
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Kacprzak SM, Van Aken O. Carbon starvation, senescence and specific mitochondrial stresses, but not nitrogen starvation and general stresses, are major triggers for mitophagy in Arabidopsis. Autophagy 2022; 18:2894-2912. [PMID: 35311445 PMCID: PMC9673927 DOI: 10.1080/15548627.2022.2054039] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Selective degradation of mitochondria by autophagy (mitophagy) is thought to play an important role in mitochondrial quality control, but our understanding of which conditions induce mitophagy in plants is limited. Here, we developed novel reporter lines to monitor mitophagy in plants and surveyed the rate of mitophagy under a wide range of stresses and developmental conditions. Especially carbon starvation induced by dark-incubation causes a dramatic increase in mitophagy within a few hours, further increasing as dark-induced senescence progresses. Natural senescence was also a strong trigger of mitophagy, peaking when leaf yellowing became prominent. In contrast, nitrogen starvation, a trigger of general autophagy, does not induce strong increases in mitophagy. Similarly, general stresses such as hydrogen peroxide, heat, UV-B and hypoxia did not appear to trigger substantial mitophagy in plants. Additionally, we exposed plants to inhibitors of the mitochondrial electron transport chain, mitochondrial translation and protein import. Although short-term treatments did not induce high mitophagy rates, longer term exposures to uncoupling agent and inhibitors of mitochondrial protein import/translation could clearly increase mitophagic flux. These findings could further be confirmed using confocal microscopy. To validate that mitophagy is mediated by the autophagy pathway, we showed that mitophagic flux is abolished or strongly decreased in atg5/AuTophaGy 5 and atg11 mutants, respectively. Finally, we observed high rates of mitophagy in etiolated seedlings, which remarkably was completely repressed within 6 h after light exposure. In conclusion, we propose that dark-induced carbon starvation, natural senescence and specific mitochondrial stresses are key triggers of mitophagy in plants.Abbreviations: AA: antimycin A; ATG: AuToPhagy related; ConA: concanamycin A; DIS: dark-induced senescence; Dox: doxycycline; FCCP: carbonyl cyanide-p-trifluoromethoxyphenylhydrazone; GFP: green fluorescent protein; IDH1: isocitrate dehydrogenase 1; MB: MitoBlock-6; Mito-GFP: transgenic Arabidopsis line expressing a mitochondrially targeted protein fused to GFP; mtETC: mitochondrial electron transport chain; OXPHOS: oxidative phosphorylation; PQC: protein quality control; TOM20: Translocase of Outer Membrane 20.
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Affiliation(s)
| | - Olivier Van Aken
- Department of Biology, Lund University, Lund, Sweden,CONTACT Olivier Van Aken Molecular Cell Biology, Department of Biology, Lund, Sweden
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Wan C, Ling Q. Functions of autophagy in chloroplast protein degradation and homeostasis. FRONTIERS IN PLANT SCIENCE 2022; 13:993215. [PMID: 36247630 PMCID: PMC9557084 DOI: 10.3389/fpls.2022.993215] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Accepted: 09/05/2022] [Indexed: 06/16/2023]
Abstract
Chloroplasts are defining organelles in plant and algae, which carried out various critical metabolic processes, including photosynthesis. Roles of chloroplast protein homeostasis in plant development and stress adaptation were clearly demonstrated in previous studies, and its maintenance requires internal proteases originated from the prokaryotic ancestor. Recently, increasing evidence revealed that eukaryotic proteolytic pathways, ubiquitin-proteasome system (UPS) and autophagy, are also involved in the turnover of chloroplast proteins, in response to developmental and environmental cues. Notably, chloroplasts can be regulated via the selective degradation of chloroplast materials in a process called chlorophagy. Yet, understandings of the mechanism of chlorophagy are still rudimentary, particularly regarding its initiation and operation. Here we provide an updated overview of autophagy pathways for chloroplast protein degradation and discuss their importance for plant physiology. In addition, recent advance in analogous mitophagy in yeast and mammals will also be discussed, which provides clues for further elucidating the mechanism of chlorophagy.
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Affiliation(s)
- Chen Wan
- National Key Laboratory of Plant Molecular Genetics, CAS Centre for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Qihua Ling
- National Key Laboratory of Plant Molecular Genetics, CAS Centre for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
- Chinese Academy of Sciences (CAS) and John Innes Centre, Center of Excellence for Plant and Microbial Sciences (CEPAMS), Shanghai, China
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29
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Chattha MS, Ali Q, Haroon M, Afzal MJ, Javed T, Hussain S, Mahmood T, Solanki MK, Umar A, Abbas W, Nasar S, Schwartz-Lazaro LM, Zhou L. Enhancement of nitrogen use efficiency through agronomic and molecular based approaches in cotton. FRONTIERS IN PLANT SCIENCE 2022; 13:994306. [PMID: 36237509 PMCID: PMC9552886 DOI: 10.3389/fpls.2022.994306] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Accepted: 08/22/2022] [Indexed: 05/22/2023]
Abstract
Cotton is a major fiber crop grown worldwide. Nitrogen (N) is an essential nutrient for cotton production and supports efficient crop production. It is a crucial nutrient that is required more than any other. Nitrogen management is a daunting task for plants; thus, various strategies, individually and collectively, have been adopted to improve its efficacy. The negative environmental impacts of excessive N application on cotton production have become harmful to consumers and growers. The 4R's of nutrient stewardship (right product, right rate, right time, and right place) is a newly developed agronomic practice that provides a solid foundation for achieving nitrogen use efficiency (NUE) in cotton production. Cropping systems are equally crucial for increasing production, profitability, environmental growth protection, and sustainability. This concept incorporates the right fertilizer source at the right rate, time, and place. In addition to agronomic practices, molecular approaches are equally important for improving cotton NUE. This could be achieved by increasing the efficacy of metabolic pathways at the cellular, organ, and structural levels and NUE-regulating enzymes and genes. This is a potential method to improve the role of N transporters in plants, resulting in better utilization and remobilization of N in cotton plants. Therefore, we suggest effective methods for accelerating NUE in cotton. This review aims to provide a detailed overview of agronomic and molecular approaches for improving NUE in cotton production, which benefits both the environment and growers.
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Affiliation(s)
- Muhammad Sohaib Chattha
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-Products, Institute of Agro-Product Safety and Nutrition, Zhejiang Academy of Agricultural Sciences, Hangzhou, China
- School of Plant, Environmental and Soil Sciences, Louisiana State University Agricultural Center, Baton Rouge, LA, United States
| | - Qurban Ali
- Laboratory of Integrated Management of Crop Diseases and Pests, Department of Plant Pathology, College of Plant Protection, Ministry of Education, Nanjing Agricultural University, Nanjing, China
| | - Muhammad Haroon
- National Key Laboratory of Crop Genetic Improvement and National Centre of Plant Gene Research (Wuhan), Huazhong Agricultural University, Wuhan, China
| | | | - Talha Javed
- College of Agriculture, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Sadam Hussain
- Department of Agronomy, University of Agriculture Faisalabad, Faisalabad, Pakistan
| | - Tahir Mahmood
- Department of Plant Breeding & Genetics, Pir Mehr Ali Shah Arid Agriculture University, Rawalpindi, Pakistan
| | - Manoj K. Solanki
- Institute of Biology, Biotechnology and Environmental Protection, Faculty of Natural Sciences, University of Silesia in Katowice, Katowice, Poland
| | - Aisha Umar
- Institute of Botany, University of the Punjab, Lahore, Pakistan
| | - Waseem Abbas
- National Key Laboratory of Crop Genetic Improvement and National Centre of Plant Gene Research (Wuhan), Huazhong Agricultural University, Wuhan, China
| | - Shanza Nasar
- Department of Botany, University of Gujrat Hafiz Hayat Campus, Gujrat, Pakistan
| | - Lauren M. Schwartz-Lazaro
- School of Plant, Environmental and Soil Sciences, Louisiana State University Agricultural Center, Baton Rouge, LA, United States
| | - Lei Zhou
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-Products, Institute of Agro-Product Safety and Nutrition, Zhejiang Academy of Agricultural Sciences, Hangzhou, China
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30
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Sakuraba Y. Molecular basis of nitrogen starvation-induced leaf senescence. FRONTIERS IN PLANT SCIENCE 2022; 13:1013304. [PMID: 36212285 PMCID: PMC9538721 DOI: 10.3389/fpls.2022.1013304] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2022] [Accepted: 09/08/2022] [Indexed: 06/01/2023]
Abstract
Nitrogen (N), a macronutrient, is often a limiting factor in plant growth, development, and productivity. To adapt to N-deficient environments, plants have developed elaborate N starvation responses. Under N-deficient conditions, older leaves exhibit yellowing, owing to the degradation of proteins and chlorophyll pigments in chloroplasts and subsequent N remobilization from older leaves to younger leaves and developing organs to sustain plant growth and productivity. In recent years, numerous studies have been conducted on N starvation-induced leaf senescence as one of the representative plant responses to N deficiency, revealing that leaf senescence induced by N deficiency is highly complex and intricately regulated at different levels, including transcriptional, post-transcriptional, post-translational and metabolic levels, by multiple genes and proteins. This review summarizes the current knowledge of the molecular mechanisms associated with N starvation-induced leaf senescence.
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Affiliation(s)
- Yasuhito Sakuraba
- Plant Functional Biotechnology, Biotechnology Research Center, The University of Tokyo, Tokyo, Japan
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31
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Sakil MA, Mukae K, Funada R, Kotake T, Ueno S, Aktar MM, Roni MS, Inoue-Aono Y, Moriyasu Y. Amino Acids Supplied through the Autophagy/Endocytosis Pathway Promote Starch Synthesis in Physcomitrella Protonemal Cells. PLANTS (BASEL, SWITZERLAND) 2022; 11:2157. [PMID: 36015461 PMCID: PMC9412964 DOI: 10.3390/plants11162157] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Revised: 08/06/2022] [Accepted: 08/09/2022] [Indexed: 06/15/2023]
Abstract
The physiological implications of autophagy in plant cells have not been fully elucidated. Therefore, we investigated the consequences of autophagy in the moss Physcomitrella by measuring biochemical parameters (fresh and dry weights; starch, amino acid, carbohydrate, and NH3 content) in wild-type (WT) and autophagy-deficient atg5 Physcomitrella cells. We found higher starch levels and a higher net starch synthesis rate in WT cells than in atg5 cells cultured in a glucose-containing culture medium, whereas net starch degradation was similar in the two strains cultured in a glucose-deficient culture medium. Additionally, the treatment of cells with the autophagy inhibitor 3-methyladenine suppressed starch synthesis. Loading bovine serum albumin into atg5 cells through endocytosis, i.e., supplying proteins to vacuoles in the same way as through autophagy, accelerated starch synthesis, whereas loading glutamine through the plasma membrane had no such effect, suggesting that Physcomitrella cells distinguish between different amino acid supply pathways. After net starch synthesis, NH3 levels increased in WT cells, although the change in total amino acid content did not differ between WT and atg5 cells, indicating that autophagy-produced amino acids are oxidized rapidly. We conclude that autophagy promotes starch synthesis in Physcomitrella by supplying the energy obtained by oxidizing autophagy-produced amino acids.
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Affiliation(s)
- Md. Arif Sakil
- Graduate School of Science and Engineering, Saitama University, Saitama 338-8570, Japan
- Department of Biochemistry and Molecular Biology, Bangladesh Agricultural University, Mymensingh 2202, Bangladesh
| | - Kyosuke Mukae
- Graduate School of Science and Engineering, Saitama University, Saitama 338-8570, Japan
- Research Institute for Clinical Oncology, Saitama Cancer Center, Saitama 362-0806, Japan
| | - Ryo Funada
- Graduate School of Science and Engineering, Saitama University, Saitama 338-8570, Japan
| | - Toshihisa Kotake
- Graduate School of Science and Engineering, Saitama University, Saitama 338-8570, Japan
| | - Shigeaki Ueno
- Faculty of Education, Saitama University, Saitama 338-8570, Japan
| | - Most Mohoshena Aktar
- Graduate School of Science and Engineering, Saitama University, Saitama 338-8570, Japan
- Department of Agronomy, Hajee Mohammad Danesh Science and Technology University, Dinajpur 5200, Bangladesh
| | - Md. Shyduzzaman Roni
- Graduate School of Science and Engineering, Saitama University, Saitama 338-8570, Japan
- Department of Horticulture, Bangabandhu Sheikh Mujibur Rahman Agricultural University, Gazipur 1706, Bangladesh
| | - Yuko Inoue-Aono
- Graduate School of Science and Engineering, Saitama University, Saitama 338-8570, Japan
| | - Yuji Moriyasu
- Graduate School of Science and Engineering, Saitama University, Saitama 338-8570, Japan
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32
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Chloroplasts Protein Quality Control and Turnover: A Multitude of Mechanisms. Int J Mol Sci 2022; 23:ijms23147760. [PMID: 35887108 PMCID: PMC9319218 DOI: 10.3390/ijms23147760] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Revised: 07/11/2022] [Accepted: 07/12/2022] [Indexed: 11/16/2022] Open
Abstract
As the organelle of photosynthesis and other important metabolic pathways, chloroplasts contain up to 70% of leaf proteins with uniquely complex processes in synthesis, import, assembly, and turnover. Maintaining functional protein homeostasis in chloroplasts is vitally important for the fitness and survival of plants. Research over the past several decades has revealed a multitude of mechanisms that play important roles in chloroplast protein quality control and turnover under normal and stress conditions. These mechanisms include: (i) endosymbiotically-derived proteases and associated proteins that play a vital role in maintaining protein homeostasis inside the chloroplasts, (ii) the ubiquitin-dependent turnover of unimported chloroplast precursor proteins to prevent their accumulation in the cytosol, (iii) chloroplast-associated degradation of the chloroplast outer-membrane translocon proteins for the regulation of chloroplast protein import, (iv) chloroplast unfolded protein response triggered by accumulated unfolded and misfolded proteins inside the chloroplasts, and (v) vesicle-mediated degradation of chloroplast components in the vacuole. Here, we provide a comprehensive review of these diverse mechanisms of chloroplast protein quality control and turnover and discuss important questions that remain to be addressed in order to better understand and improve important chloroplast functions.
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33
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Duckney PJ, Wang P, Hussey PJ. Membrane contact sites and cytoskeleton-membrane interactions in autophagy. FEBS Lett 2022; 596:2093-2103. [PMID: 35648104 PMCID: PMC9545284 DOI: 10.1002/1873-3468.14414] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Revised: 05/10/2022] [Accepted: 05/12/2022] [Indexed: 11/23/2022]
Abstract
In Eukaryotes, organelle interactions occur at specialised contact sites between organelle membranes. Contact sites are regulated by specialised tethering proteins, which bring organelle membranes into close proximity, and facilitate functional crosstalk between compartments. While contact site proteins are well characterised in mammals and yeast, the regulators of plant contact site formation are only now beginning to emerge. Having unique subcellular structures, plants must also utilise unique mechanisms of organelle interaction to regulate plant‐specific functions. The recently characterised NETWORKED proteins are the first dedicated family of plant‐specific contact site proteins. Research into the NET proteins and their interacting partners continues to uncover plant‐specific mechanisms of organelle interaction and the importance of these organelle contacts to plant life. Moreover, it is becoming increasingly apparent that organelle interactions are fundamental to autophagy in plants. Here, we will present recent developments in our understanding of the mechanisms of plant organelle interactions, their functions, and emerging roles in autophagy.
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Affiliation(s)
| | - Pengwei Wang
- Key Laboratory of Horticultural Plant Biology, College of Horticulture and Forestry Sciences, Huazhong Agricultural University, Wuhan, China
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34
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Luong AM, Koestel J, Bhati KK, Batoko H. Cargo receptors and adaptors for selective autophagy in plant cells. FEBS Lett 2022; 596:2104-2132. [PMID: 35638898 DOI: 10.1002/1873-3468.14412] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2022] [Revised: 05/08/2022] [Accepted: 05/23/2022] [Indexed: 11/06/2022]
Abstract
Plant selective (macro)autophagy is a highly regulated process whereby eukaryotic cells spatiotemporally degrade some of their constituents that have become superfluous or harmful. The identification and characterization of the factors determining this selectivity make it possible to integrate selective (macro)autophagy into plant cell physiology and homeostasis. The specific cargo receptors and/or scaffold proteins involved in this pathway are generally not structurally conserved, as are the biochemical mechanisms underlying recognition and integration of a given cargo into the autophagosome in different cell types. This review discusses the few specific cargo receptors described in plant cells to highlight key features of selective autophagy in the plant kingdom and its integration with plant physiology, so as to identify evolutionary convergence and knowledge gaps to be filled by future research.
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Affiliation(s)
- Ai My Luong
- Louvain Institute of Biomolecular Science and Technology, University of Louvain Croix du Sud 4, L7.07.14, 1348, Louvain-la-Neuve, Belgium
| | - Jérôme Koestel
- Louvain Institute of Biomolecular Science and Technology, University of Louvain Croix du Sud 4, L7.07.14, 1348, Louvain-la-Neuve, Belgium
| | - Kaushal Kumar Bhati
- Louvain Institute of Biomolecular Science and Technology, University of Louvain Croix du Sud 4, L7.07.14, 1348, Louvain-la-Neuve, Belgium
| | - Henri Batoko
- Louvain Institute of Biomolecular Science and Technology, University of Louvain Croix du Sud 4, L7.07.14, 1348, Louvain-la-Neuve, Belgium
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35
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Magen S, Seybold H, Laloum D, Avin-Wittenberg T. Metabolism and autophagy in plants - A perfect match. FEBS Lett 2022; 596:2133-2151. [PMID: 35470431 DOI: 10.1002/1873-3468.14359] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Revised: 04/19/2022] [Accepted: 04/20/2022] [Indexed: 01/18/2023]
Abstract
Autophagy is a eukaryotic cellular transport mechanism that delivers intracellular macromolecules, proteins, and even organelles to a lytic organelle (vacuole in yeast and plants/lysosome in animals) for degradation and nutrient recycling. The process is mediated by highly conserved Autophagy-Related (ATG) proteins. In plants, autophagy maintains cellular homeostasis under favorable conditions, guaranteeing normal plant growth and fitness. Severe stress such as nutrient starvation and plant senescence further induce it, thus ensuring plant survival under unfavorable conditions by providing nutrients through the removal of damaged or aged proteins, or organelles. In this article, we examine the interplay between metabolism and autophagy, focusing on the different aspects of this reciprocal relationship. We show that autophagy has a strong influence on a range of metabolic processes, whereas, at the same time, even single metabolites can activate autophagy. We highlight the involvement of ATG genes in metabolism, examine the role of the macronutrients carbon and nitrogen, as well as various micronutrients, and take a closer look at how the interaction between autophagy and metabolism impacts on plant phenotypes and yield.
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Affiliation(s)
- Sahar Magen
- Department of Plant and Environmental Sciences, Alexander Silberman Institute of Life Sciences, the Hebrew University of Jerusalem, Israel
| | - Heike Seybold
- Department of Plant and Environmental Sciences, Alexander Silberman Institute of Life Sciences, the Hebrew University of Jerusalem, Israel
| | - Daniel Laloum
- Department of Plant and Environmental Sciences, Alexander Silberman Institute of Life Sciences, the Hebrew University of Jerusalem, Israel
| | - Tamar Avin-Wittenberg
- Department of Plant and Environmental Sciences, Alexander Silberman Institute of Life Sciences, the Hebrew University of Jerusalem, Israel
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36
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Feng Q, De Rycke R, Dagdas Y, Nowack MK. Autophagy promotes programmed cell death and corpse clearance in specific cell types of the Arabidopsis root cap. Curr Biol 2022; 32:2110-2119.e3. [PMID: 35390283 DOI: 10.1016/j.cub.2022.03.053] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Revised: 03/04/2022] [Accepted: 03/17/2022] [Indexed: 12/11/2022]
Abstract
Autophagy is a conserved quality control pathway that mediates the degradation of cellular components by targeting them to the lysosomes or vacuoles.1 Autophagy has been implicated in the regulation of some regulated cell death processes in animal systems.2 However, its function in developmentally controlled programmed cell death (dPCD) in plants remains little studied and controversial.3 Some studies have reported autophagy pro-survival roles,4,5 while others have suggested pro-death functions for autophagy,6,7 calling for further detailed investigations. Here, we investigated the role of autophagy in dPCD using the Arabidopsis root cap as an accessible and genetically tractable model system.8 In Arabidopsis, dPCD is an integral part of root cap differentiation, restricting root cap organ size to the root meristem.9 The root cap consists of two distinct tissues: the proximally positioned columella that is located at the very root tip and the lateral root cap (LRC) that flanks the root meristem up to its distal end at the start of the root elongation zone.10 We show that autophagic flux strongly increased prior to dPCD execution in both root cap tissues and depends on the key autophagy genes ATG2, ATG5, and ATG7. Systemic and organ-specific mutation of these genes shows delayed PCD execution and lack of postmortem corpse clearance in the columella but no defects in dPCD execution or corpse clearance in the distal LRC. Our results reveal a high degree of cell-type specificity in autophagy functions and suggest that autophagy roles in dPCD can considerably diverge between different cell types of the same plant organ.
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Affiliation(s)
- Qiangnan Feng
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Technologiepark 71, 9052 Ghent, Belgium; VIB Center for Plant Systems Biology, Technologiepark 71, 9052 Ghent, Belgium
| | - Riet De Rycke
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Technologiepark 71, 9052 Ghent, Belgium; VIB Center for Plant Systems Biology, Technologiepark 71, 9052 Ghent, Belgium; VIB Bioimaging Core, Technologiepark 71, 9052 Ghent, Belgium
| | - Yasin Dagdas
- Gregor Mendel Institute (GMI), Austrian Academy of Sciences, Vienna BioCenter (VBC), Vienna, Austria
| | - Moritz K Nowack
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Technologiepark 71, 9052 Ghent, Belgium; VIB Center for Plant Systems Biology, Technologiepark 71, 9052 Ghent, Belgium.
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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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Chloroplast Protein Tic55 Involved in Dark-Induced Senescence through AtbHLH/AtWRKY-ANAC003 Controlling Pathway of Arabidopsis thaliana. Genes (Basel) 2022; 13:genes13020308. [PMID: 35205352 PMCID: PMC8872272 DOI: 10.3390/genes13020308] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2021] [Revised: 01/26/2022] [Accepted: 02/02/2022] [Indexed: 12/04/2022] Open
Abstract
The chloroplast comprises the outer and inner membranes that are composed of the translocon protein complexes Toc and Tic (translocon at the outer/inner envelope membrane of chloroplasts), respectively. Tic55, a chloroplast Tic protein member, was shown to be not vital for functional protein import in Arabidopsis from previous studies. Instead, Tic55 was revealed to be a dark-induced senescence-related protein in our earlier study. To explore whether Tic55 elicits other biological functions, a tic55-II knockout mutant (SALK_086048) was characterized under different stress treatments. Abiotic stress conditions, such as cold, heat, and high osmotic pressure, did not cause visible effects on tic55-II mutant plant, when compared to the wild type (WT). In contrast, senescence was induced in the individually darkened leaves (IDLs), resulting in the differential expression of the senescence-related genes PEROXISOME DEFECTIVE 1 (PED1), BLUE COPPER-BINDING PROTEIN (BCB), SENESCENCE 1 (SEN1), and RUBISCO SMALL SUBUNIT GENE 2B (RBCS2B). The absence of Tic55 in tic55-II knockout mutant inhibited expression of the senescence-related genes PED1, BCB, and SEN1 at different stages of dark adaptation, while causing stimulation of RBCS2B gene expression at an early stage of dark response. Finally, yeast one-hybrid assays located the ANAC003 promoter region with cis-acting elements are responsible for binding to the different AtbHLH proteins, thereby causing the transactivation of an HIS3 reporter gene. ANAC003 was shown previously as a senescence-related protein and its activation would lead to expression of senescence-associated genes (SAGs), resulting in plant senescence. Thus, we propose a hypothetical model in which three signaling pathways may be involved in controlling the expression of ANAC003, followed by expression of SAGs that in turn leads to leaf senescence in Arabidopsis by this study and previous data.
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Ni J, Li Y, Xiang Y, Yang X, Jia L, Yue J, Wang H. Autophagic degradation of the chloroplastic 2-phosphoglycolate phosphatase TaPGLP1 in wheat. PLANT CELL REPORTS 2022; 41:473-487. [PMID: 34981152 DOI: 10.1007/s00299-021-02820-3] [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: 09/21/2021] [Accepted: 11/23/2021] [Indexed: 06/14/2023]
Abstract
KEY MESSAGE TaPGLP1, a chloroplast stromal 2-phosphoglycolate phosphatase of wheat, is an ATG8-interacting protein and undergoes autophagic degradation in starvation-treated wheat mesophyll protoplasts. Selective autophagy in plants has been shown to target diverse cellular cargoes including whole chloroplasts (Chlorophagy) and several chloroplast components (Piecemeal chlorophagy). Most cargoes of selective autophagy are captured by the autophagic machinery through their direct or indirect interactions with the autophagy-essential factor ATG8. Here, we reported a new ATG8-interacting cargo of piecemeal chlorophagy, the wheat photorespiratory 2-phosphoglycolate phosphatase TaPGLP1. The TaPGLP1-mCherry fusions expressed in wheat protoplasts located in the chloroplast stroma. Strikingly, these fusions are translocated into newly formed chloroplast surface protrusions after a long time incubation of protoplasts in a nutrition-free solution. Visualization of co-expressed TaPGLP1-mCherry and the autophagy marker GFP-TaATG8a revealed physical associations of TaPGLP1-mCherry-accumulating chloroplast protrusions with autophagic structures, implying the delivery of TaPGLP1-mCherry fusions from chloroplasts to the autophagic machinery. TaPGLP1-mCherry fusions were also detected in the GFP-TaATG8a-labelled autophagic bodies undergoing degradation in the vacuoles, which suggested the autophagic degradation of TaPGLP1. This autophagic degradation of TaPGLP1 was further demonstrated by the enhanced stability of TaPGLP1-mCherry in protoplasts with impaired autophagy. Expression of TaPGLP1-mCherry in protoplasts stimulated an enhanced autophagy level probably adopted by cells to degrade the over-produced TaPGLP1-mCherry fusions. Results from gene silencing assays showed the requirement of ATG2s and ATG7s in the autophagic degradation of TaPGLP1. Additionally, TaPGLP1 was shown to interact with ATG8 family members. Collectively, our data suggest that autophagy mediates the degradation of the chloroplast stromal protein TaPGLP1 in starvation-treated mesophyll protoplasts.
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Affiliation(s)
- Jiayao Ni
- College of Life Sciences, Tianjin Key Laboratory of Animal and Plant Resistance, Tianjin Normal University, 393#, BinShuiXi Road, Xiqing, Tianjin, 300387, China
| | - Yuru Li
- College of Life Sciences, Tianjin Key Laboratory of Animal and Plant Resistance, Tianjin Normal University, 393#, BinShuiXi Road, Xiqing, Tianjin, 300387, China
| | - Yue Xiang
- College of Life Sciences, Tianjin Key Laboratory of Animal and Plant Resistance, Tianjin Normal University, 393#, BinShuiXi Road, Xiqing, Tianjin, 300387, China
| | - Xiangyun Yang
- College of Life Sciences, Tianjin Key Laboratory of Animal and Plant Resistance, Tianjin Normal University, 393#, BinShuiXi Road, Xiqing, Tianjin, 300387, China
| | - Lei Jia
- College of Life Sciences, Tianjin Key Laboratory of Animal and Plant Resistance, Tianjin Normal University, 393#, BinShuiXi Road, Xiqing, Tianjin, 300387, China
| | - Jieyu Yue
- College of Life Sciences, Tianjin Key Laboratory of Animal and Plant Resistance, Tianjin Normal University, 393#, BinShuiXi Road, Xiqing, Tianjin, 300387, China
| | - Huazhong Wang
- College of Life Sciences, Tianjin Key Laboratory of Animal and Plant Resistance, Tianjin Normal University, 393#, BinShuiXi Road, Xiqing, Tianjin, 300387, China.
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Shen J, Chen Q, Li Z, Zheng Q, Xu Y, Zhou H, Mao H, Shen Q, Liu P. Proteomic and metabolomic analysis of Nicotiana benthamiana under dark stress. FEBS Open Bio 2022; 12:231-249. [PMID: 34792288 PMCID: PMC8727940 DOI: 10.1002/2211-5463.13331] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Revised: 10/15/2021] [Accepted: 11/13/2021] [Indexed: 11/08/2022] Open
Abstract
Exposure to extended periods of darkness is a common source of abiotic stress that significantly affects plant growth and development. To understand how Nicotiana benthamiana responds to dark stress, the proteomes and metabolomes of leaves treated with darkness were studied. In total, 5763 proteins and 165 primary metabolites were identified following dark treatment. Additionally, the expression of autophagy-related gene (ATG) proteins was transiently upregulated. Weighted gene coexpression network analysis (WGCNA) was utilized to find the protein modules associated with the response to dark stress. A total of four coexpression modules were obtained. The results indicated that heat-shock protein (HSP70), SnRK1-interacting protein 1, 2A phosphatase-associated protein of 46 kDa (Tap46), and glutamate dehydrogenase (GDH) might play crucial roles in N. benthamiana's response to dark stress. Furthermore, a protein-protein interaction (PPI) network was constructed and top-degreed proteins were predicted to identify potential key factors in the response to dark stress. These proteins include isopropylmalate isomerase (IPMI), eukaryotic elongation factor 5A (ELF5A), and ribosomal protein 5A (RPS5A). Finally, metabolic analysis suggested that some amino acids and sugars were involved in the dark-responsive pathways. Thus, these results provide a new avenue for understanding the defensive mechanism against dark stress at the protein and metabolic levels in N. benthamiana.
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Affiliation(s)
- Juan‐Juan Shen
- College of ChemistryZhengzhou UniversityZhengzhouChina
- Chemistry Research Institution of Henan Academy of SciencesZhengzhouChina
| | - Qian‐Si Chen
- Zhengzhou Tobacco Research Institute of CNTCZhengzhouChina
| | - Ze‐Feng Li
- Zhengzhou Tobacco Research Institute of CNTCZhengzhouChina
| | - Qing‐Xia Zheng
- Zhengzhou Tobacco Research Institute of CNTCZhengzhouChina
| | - Ya‐Long Xu
- Zhengzhou Tobacco Research Institute of CNTCZhengzhouChina
| | - Hui‐Na Zhou
- Zhengzhou Tobacco Research Institute of CNTCZhengzhouChina
| | - Hong‐Yan Mao
- College of ChemistryZhengzhou UniversityZhengzhouChina
| | - Qi Shen
- College of ChemistryZhengzhou UniversityZhengzhouChina
| | - Ping‐Ping Liu
- Zhengzhou Tobacco Research Institute of CNTCZhengzhouChina
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Ishida H, Okashita Y, Ishida H, Hayashi M, Izumi M, Makino A, Bhuiyan NH, van Wijk KJ. GFS9 Affects Piecemeal Autophagy of Plastids in Young Seedlings of Arabidopsis thaliana. PLANT & CELL PHYSIOLOGY 2021; 62:1372-1386. [PMID: 34086965 DOI: 10.1093/pcp/pcab084] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Revised: 05/26/2021] [Accepted: 06/04/2021] [Indexed: 06/12/2023]
Abstract
Chloroplasts, and plastids in general, contain abundant protein pools that can be major sources of carbon and nitrogen for recycling. We have previously shown that chloroplasts are partially and sequentially degraded by piecemeal autophagy via the Rubisco-containing body. This degradation occurs during plant development and in response to the environment; however, little is known about the fundamental underlying mechanisms. To discover the mechanisms of piecemeal autophagy of chloroplasts/plastids, we conducted a forward-genetics screen following ethyl-methanesulfonate mutagenesis of an Arabidopsis (Arabidopsis thaliana) transgenic line expressing chloroplast-targeted green fluorescent protein (CT-GFP). This screen allowed us to isolate a mutant, gfs9-5, which hyperaccumulated cytoplasmic bodies labeled with CT-GFP of up to 1.0 μm in diameter in the young seedlings. We termed these structures plastid bodies (PBs). The mutant was defective in a membrane-trafficking factor, green fluorescent seed 9 (GFS9), and PB accumulation in gfs9-5 was promoted by darkness and nutrient deficiency. Transmission electron microscopy indicated that gfs9-5 hyperaccumulated structures corresponding to autophagosomes and PBs. gfs9-5 hyperaccumulated membrane-bound endogenous ATG8 proteins, transgenic yellow fluorescent protein (YFP)-ATG8e proteins and autophagosome-like structures labeled with YFP-ATG8e. The YFP-ATG8e signal was associated with the surface of plastids and their protrusions in gfs9-5. Double mutants of gfs9 and autophagy-defective 5 did not accumulate PBs. In gfs9-5, the YFP-ATG8e proteins and PBs could be delivered to the vacuole and autophagic flux was increased. We discuss a possible connection between GFS9 and autophagy and propose a potential use of gfs9-5 as a new tool to study piecemeal plastid autophagy.
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Affiliation(s)
- Hiroyuki Ishida
- Department of Applied Plant Science, Graduate School of Agricultural Science, Tohoku University, 468-1 Aramaki Aza Aoba, Sendai 980-8572, Japan
- School of Integrative Plant Sciences, Section of Plant Biology, Cornell University, Ithaca, NY 14853, USA
| | - Yu Okashita
- Department of Applied Plant Science, Graduate School of Agricultural Science, Tohoku University, 468-1 Aramaki Aza Aoba, Sendai 980-8572, Japan
| | - Hiromi Ishida
- Department of Applied Plant Science, Graduate School of Agricultural Science, Tohoku University, 468-1 Aramaki Aza Aoba, Sendai 980-8572, Japan
- School of Integrative Plant Sciences, Section of Plant Biology, Cornell University, Ithaca, NY 14853, USA
| | - Makoto Hayashi
- Department of Bioscience, Nagahama Institute of Bioscience and Technology, Tamura 1266, Nagahama, Shiga 526-0829, Japan
| | - Masanori Izumi
- Center for Sustainable Resource Science, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - Amane Makino
- Department of Applied Plant Science, Graduate School of Agricultural Science, Tohoku University, 468-1 Aramaki Aza Aoba, Sendai 980-8572, Japan
| | - Nazmul H Bhuiyan
- School of Integrative Plant Sciences, Section of Plant Biology, Cornell University, Ithaca, NY 14853, USA
- Eurofins Lancaster Lab PSS, Richmond, VA, USA
| | - Klaas J van Wijk
- School of Integrative Plant Sciences, Section of Plant Biology, Cornell University, Ithaca, NY 14853, USA
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43
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Karia P, Yoshioka K, Moeder W. Multiple phosphorylation events of the mitochondrial membrane protein TTM1 regulate cell death during senescence. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2021; 108:766-780. [PMID: 34409658 DOI: 10.1111/tpj.15470] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Revised: 07/31/2021] [Accepted: 08/03/2021] [Indexed: 06/13/2023]
Abstract
The role of mitochondria in programmed cell death (PCD) during animal growth and development is well documented, but much less is known for plants. We previously showed that the Arabidopsis thaliana triphosphate tunnel metalloenzyme (TTM) proteins TTM1 and TTM2 are tail-anchored proteins that localize in the mitochondrial outer membrane and participate in PCD during senescence and immunity, respectively. Here, we show that TTM1 is specifically involved in senescence induced by abscisic acid (ABA). Moreover, phosphorylation of TTM1 by multiple mitogen-activated protein (MAP) kinases regulates its function and turnover. A combination of proteomics and in vitro kinase assays revealed three major phosphorylation sites of TTM1 (Ser10, Ser437, and Ser490). Ser437, which is phosphorylated upon perception of senescence cues such as ABA and prolonged darkness, is phosphorylated by the MAP kinases MPK3 and MPK4, and Ser437 phosphorylation is essential for TTM1 function in senescence. These MPKs, together with three additional MAP kinases (MPK1, MPK7, and MPK6), also phosphorylate Ser10 and Ser490, marking TTM1 for protein turnover, which likely prevents uncontrolled cell death. Taken together, our results show that multiple MPKs regulate the function and turnover of the mitochondrial protein TTM1 during senescence-associated cell death, revealing a novel link between mitochondria and PCD.
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Affiliation(s)
- Purva Karia
- Department of Cell and Systems Biology, University of Toronto, 25 Willcocks Street, Toronto, ON, M5S 3B2, Canada
| | - Keiko Yoshioka
- Department of Cell and Systems Biology, University of Toronto, 25 Willcocks Street, Toronto, ON, M5S 3B2, Canada
- Center for the Analysis of Genome Evolution and Function (CAGEF), University of Toronto, 25 Willcocks Street, Toronto, ON, M5S 3B2, Canada
| | - Wolfgang Moeder
- Department of Cell and Systems Biology, University of Toronto, 25 Willcocks Street, Toronto, ON, M5S 3B2, Canada
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Rehman NU, Zeng P, Mo Z, Guo S, Liu Y, Huang Y, Xie Q. Conserved and Diversified Mechanism of Autophagy between Plants and Animals upon Various Stresses. Antioxidants (Basel) 2021; 10:1736. [PMID: 34829607 PMCID: PMC8615172 DOI: 10.3390/antiox10111736] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Revised: 10/27/2021] [Accepted: 10/27/2021] [Indexed: 01/01/2023] Open
Abstract
Autophagy is a highly conserved degradation mechanism in eukaryotes, executing the breakdown of unwanted cell components and subsequent recycling of cellular material for stress relief through vacuole-dependence in plants and yeast while it is lysosome-dependent in animal manner. Upon stress, different types of autophagy are stimulated to operate certain biological processes by employing specific selective autophagy receptors (SARs), which hijack the cargo proteins or organelles to the autophagy machinery for subsequent destruction in the vacuole/lysosome. Despite recent advances in autophagy, the conserved and diversified mechanism of autophagy in response to various stresses between plants and animals still remain a mystery. In this review, we intend to summarize and discuss the characterization of the SARs and their corresponding processes, expectantly advancing the scope and perspective of the evolutionary fate of autophagy between plants and animals.
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Affiliation(s)
- Naveed Ur Rehman
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Guangdong Provincial Key Laboratory of Plant Molecular Breeding, South China Agricultural University, Guangzhou 510642, China; (N.U.R.); (P.Z.); (Z.M.); (S.G.)
| | - Peichun Zeng
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Guangdong Provincial Key Laboratory of Plant Molecular Breeding, South China Agricultural University, Guangzhou 510642, China; (N.U.R.); (P.Z.); (Z.M.); (S.G.)
| | - Zulong Mo
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Guangdong Provincial Key Laboratory of Plant Molecular Breeding, South China Agricultural University, Guangzhou 510642, China; (N.U.R.); (P.Z.); (Z.M.); (S.G.)
| | - Shaoying Guo
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Guangdong Provincial Key Laboratory of Plant Molecular Breeding, South China Agricultural University, Guangzhou 510642, China; (N.U.R.); (P.Z.); (Z.M.); (S.G.)
| | - Yunfeng Liu
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Life Sciences and Technology, Guangxi University, Nanning 530004, China;
| | - Yifeng Huang
- Institute of Crop and Nuclear Technology Utilization, Zhejiang Academy of Agricultural Science, Hangzhou 310001, China
| | - Qingjun Xie
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Guangdong Provincial Key Laboratory of Plant Molecular Breeding, South China Agricultural University, Guangzhou 510642, China; (N.U.R.); (P.Z.); (Z.M.); (S.G.)
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45
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Samal B, Chatterjee S. Bacterial quorum sensing facilitates Xanthomonas campesteris pv. campestris invasion of host tissue to maximize disease symptoms. JOURNAL OF EXPERIMENTAL BOTANY 2021; 72:6524-6543. [PMID: 33993246 DOI: 10.1093/jxb/erab211] [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: 11/03/2020] [Accepted: 05/12/2021] [Indexed: 06/12/2023]
Abstract
Quorum sensing (QS) helps the Xanthomonas group of phytopathogens to infect several crop plants. The vascular phytopathogen Xanthomonas campestris pv. campestris (Xcc) is the causal agent of black rot disease on Brassicaceae leaves, where a typical v-shaped lesion spans both vascular and mesophyll regions with progressive leaf chlorosis. Recently, the role of QS has been elucidated during Xcc early infection stages. However, a detailed insight into the possible role of QS-regulated bacterial invasion in host chlorophagy during late infection stages remains elusive. In this study, using QS-responsive whole-cell bioreporters of Xcc, we present a detailed chronology of QS-facilitated Xcc colonization in the mesophyll region of cabbage (Brassica oleracea) leaves. We report that QS-enabled localization of Xcc to parenchymal chloroplasts triggers leaf chlorosis and promotion of systemic infection. Our results indicate that the QS response in the Xanthomonas group of vascular phytopathogens maximizes their population fitness across host tissues to trigger stage-specific host chlorophagy and establish a systemic infection.
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Affiliation(s)
- Biswajit Samal
- Lab of Plant-Microbe Interactions, Centre for DNA Fingerprinting and Diagnostics, Hyderabad, Telangana, India
- Graduate Studies, Manipal Academy of Higher Education, Manipal, Karnataka, India
| | - Subhadeep Chatterjee
- Lab of Plant-Microbe Interactions, Centre for DNA Fingerprinting and Diagnostics, Hyderabad, Telangana, India
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Gems D, Kern CC, Nour J, Ezcurra M. Reproductive Suicide: Similar Mechanisms of Aging in C. elegans and Pacific Salmon. Front Cell Dev Biol 2021; 9:688788. [PMID: 34513830 PMCID: PMC8430333 DOI: 10.3389/fcell.2021.688788] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Accepted: 07/21/2021] [Indexed: 12/17/2022] Open
Abstract
In some species of salmon, reproductive maturity triggers the development of massive pathology resulting from reproductive effort, leading to rapid post-reproductive death. Such reproductive death, which occurs in many semelparous organisms (with a single bout of reproduction), can be prevented by blocking reproductive maturation, and this can increase lifespan dramatically. Reproductive death is often viewed as distinct from senescence in iteroparous organisms (with multiple bouts of reproduction) such as humans. Here we review the evidence that reproductive death occurs in C. elegans and discuss what this means for its use as a model organism to study aging. Inhibiting insulin/IGF-1 signaling and germline removal suppresses reproductive death and greatly extends lifespan in C. elegans, but can also extend lifespan to a small extent in iteroparous organisms. We argue that mechanisms of senescence operative in reproductive death exist in a less catastrophic form in iteroparous organisms, particularly those that involve costly resource reallocation, and exhibit endocrine-regulated plasticity. Thus, mechanisms of senescence in semelparous organisms (including plants) and iteroparous ones form an etiological continuum. Therefore understanding mechanisms of reproductive death in C. elegans can teach us about some mechanisms of senescence that are operative in iteroparous organisms.
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Affiliation(s)
- David Gems
- Institute of Healthy Ageing, Research Department of Genetics, Evolution and Environment, University College London, London, United Kingdom
| | - Carina C. Kern
- Institute of Healthy Ageing, Research Department of Genetics, Evolution and Environment, University College London, London, United Kingdom
| | - Joseph Nour
- Institute of Healthy Ageing, Research Department of Genetics, Evolution and Environment, University College London, London, United Kingdom
| | - Marina Ezcurra
- School of Biosciences, University of Kent, Canterbury, United Kingdom
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Domínguez F, Cejudo FJ. Chloroplast dismantling in leaf senescence. JOURNAL OF EXPERIMENTAL BOTANY 2021; 72:5905-5918. [PMID: 33959761 PMCID: PMC8760853 DOI: 10.1093/jxb/erab200] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Accepted: 05/03/2021] [Indexed: 05/02/2023]
Abstract
In photosynthetic plant cells, chloroplasts act as factories of metabolic intermediates that support plant growth. Chloroplast performance is highly influenced by environmental cues. Thus, these organelles have the additional function of sensing ever changing environmental conditions, thereby playing a key role in harmonizing the growth and development of different organs and in plant acclimation to the environment. Moreover, chloroplasts constitute an excellent source of metabolic intermediates that are remobilized to sink tissues during senescence so that chloroplast dismantling is a tightly regulated process that plays a key role in plant development. Stressful environmental conditions enhance the generation of reactive oxygen species (ROS) by chloroplasts, which may lead to oxidative stress causing damage to the organelle. These environmental conditions trigger mechanisms that allow the rapid dismantling of damaged chloroplasts, which is crucial to avoid deleterious effects of toxic by-products of the degradative process. In this review, we discuss the effect of redox homeostasis and ROS generation in the process of chloroplast dismantling. Furthermore, we summarize the structural and biochemical events, both intra- and extraplastid, that characterize the process of chloroplast dismantling in senescence and in response to environmental stresses.
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Affiliation(s)
- Fernando Domínguez
- Instituto de Bioquímica Vegetal y Fotosíntesis, Universidad de Sevilla and Consejo Superior de Investigaciones Científicas, Avda. Américo Vespucio 49, 41092-Sevilla, Spain
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Lemke MD, Fisher KE, Kozlowska MA, Tano DW, Woodson JD. The core autophagy machinery is not required for chloroplast singlet oxygen-mediated cell death in the Arabidopsis thaliana plastid ferrochelatase two mutant. BMC PLANT BIOLOGY 2021; 21:342. [PMID: 34281507 PMCID: PMC8290626 DOI: 10.1186/s12870-021-03119-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/28/2021] [Accepted: 06/22/2021] [Indexed: 06/13/2023]
Abstract
BACKGROUND Chloroplasts respond to stress and changes in the environment by producing reactive oxygen species (ROS) that have specific signaling abilities. The ROS singlet oxygen (1O2) is unique in that it can signal to initiate cellular degradation including the selective degradation of damaged chloroplasts. This chloroplast quality control pathway can be monitored in the Arabidopsis thaliana mutant plastid ferrochelatase two (fc2) that conditionally accumulates chloroplast 1O2 under diurnal light cycling conditions leading to rapid chloroplast degradation and eventual cell death. The cellular machinery involved in such degradation, however, remains unknown. Recently, it was demonstrated that whole damaged chloroplasts can be transported to the central vacuole via a process requiring autophagosomes and core components of the autophagy machinery. The relationship between this process, referred to as chlorophagy, and the degradation of 1O2-stressed chloroplasts and cells has remained unexplored. RESULTS To further understand 1O2-induced cellular degradation and determine what role autophagy may play, the expression of autophagy-related genes was monitored in 1O2-stressed fc2 seedlings and found to be induced. Although autophagosomes were present in fc2 cells, they did not associate with chloroplasts during 1O2 stress. Mutations affecting the core autophagy machinery (atg5, atg7, and atg10) were unable to suppress 1O2-induced cell death or chloroplast protrusion into the central vacuole, suggesting autophagosome formation is dispensable for such 1O2-mediated cellular degradation. However, both atg5 and atg7 led to specific defects in chloroplast ultrastructure and photosynthetic efficiencies, suggesting core autophagy machinery is involved in protecting chloroplasts from photo-oxidative damage. Finally, genes predicted to be involved in microautophagy were shown to be induced in stressed fc2 seedlings, indicating a possible role for an alternate form of autophagy in the dismantling of 1O2-damaged chloroplasts. CONCLUSIONS Our results support the hypothesis that 1O2-dependent cell death is independent from autophagosome formation, canonical autophagy, and chlorophagy. Furthermore, autophagosome-independent microautophagy may be involved in degrading 1O2-damaged chloroplasts. At the same time, canonical autophagy may still play a role in protecting chloroplasts from 1O2-induced photo-oxidative stress. Together, this suggests chloroplast function and degradation is a complex process utilizing multiple autophagy and degradation machineries, possibly depending on the type of stress or damage incurred.
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Affiliation(s)
- Matthew D. Lemke
- The School of Plant Sciences, University of Arizona, Tucson, AZ 85721-0036 USA
| | - Karen E. Fisher
- The School of Plant Sciences, University of Arizona, Tucson, AZ 85721-0036 USA
| | - Marta A. Kozlowska
- The School of Plant Sciences, University of Arizona, Tucson, AZ 85721-0036 USA
| | - David W. Tano
- The School of Plant Sciences, University of Arizona, Tucson, AZ 85721-0036 USA
| | - Jesse D. Woodson
- The School of Plant Sciences, University of Arizona, Tucson, AZ 85721-0036 USA
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Gomez RE, Lupette J, Chambaud C, Castets J, Ducloy A, Cacas JL, Masclaux-Daubresse C, Bernard A. How Lipids Contribute to Autophagosome Biogenesis, a Critical Process in Plant Responses to Stresses. Cells 2021; 10:1272. [PMID: 34063958 PMCID: PMC8224036 DOI: 10.3390/cells10061272] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 05/03/2021] [Accepted: 05/17/2021] [Indexed: 01/18/2023] Open
Abstract
Throughout their life cycle, plants face a tremendous number of environmental and developmental stresses. To respond to these different constraints, they have developed a set of refined intracellular systems including autophagy. This pathway, highly conserved among eukaryotes, is induced by a wide range of biotic and abiotic stresses upon which it mediates the degradation and recycling of cytoplasmic material. Central to autophagy is the formation of highly specialized double membrane vesicles called autophagosomes which select, engulf, and traffic cargo to the lytic vacuole for degradation. The biogenesis of these structures requires a series of membrane remodeling events during which both the quantity and quality of lipids are critical to sustain autophagy activity. This review highlights our knowledge, and raises current questions, regarding the mechanism of autophagy, and its induction and regulation upon environmental stresses with a particular focus on the fundamental contribution of lipids. How autophagy regulates metabolism and the recycling of resources, including lipids, to promote plant acclimation and resistance to stresses is further discussed.
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Affiliation(s)
- Rodrigo Enrique Gomez
- Laboratoire de Biogenèse Membranaire, UMR 5200, CNRS, Université de Bordeaux, F-33140 Villenave d’Ornon, France; (R.E.G.); (J.L.); (C.C.); (J.C.)
| | - Josselin Lupette
- Laboratoire de Biogenèse Membranaire, UMR 5200, CNRS, Université de Bordeaux, F-33140 Villenave d’Ornon, France; (R.E.G.); (J.L.); (C.C.); (J.C.)
| | - Clément Chambaud
- Laboratoire de Biogenèse Membranaire, UMR 5200, CNRS, Université de Bordeaux, F-33140 Villenave d’Ornon, France; (R.E.G.); (J.L.); (C.C.); (J.C.)
| | - Julie Castets
- Laboratoire de Biogenèse Membranaire, UMR 5200, CNRS, Université de Bordeaux, F-33140 Villenave d’Ornon, France; (R.E.G.); (J.L.); (C.C.); (J.C.)
| | - Amélie Ducloy
- Institut Jean-Pierre Bourgin, UMR 1318 AgroParisTech-INRAE, Université Paris-Saclay, 78000 Versailles, France; (A.D.); (J.-L.C.); (C.M.-D.)
| | - Jean-Luc Cacas
- Institut Jean-Pierre Bourgin, UMR 1318 AgroParisTech-INRAE, Université Paris-Saclay, 78000 Versailles, France; (A.D.); (J.-L.C.); (C.M.-D.)
| | - Céline Masclaux-Daubresse
- Institut Jean-Pierre Bourgin, UMR 1318 AgroParisTech-INRAE, Université Paris-Saclay, 78000 Versailles, France; (A.D.); (J.-L.C.); (C.M.-D.)
| | - Amélie Bernard
- Laboratoire de Biogenèse Membranaire, UMR 5200, CNRS, Université de Bordeaux, F-33140 Villenave d’Ornon, France; (R.E.G.); (J.L.); (C.C.); (J.C.)
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Nakamura S, Hagihara S, Otomo K, Ishida H, Hidema J, Nemoto T, Izumi M. Autophagy Contributes to the Quality Control of Leaf Mitochondria. PLANT & CELL PHYSIOLOGY 2021; 62:229-247. [PMID: 33355344 PMCID: PMC8112837 DOI: 10.1093/pcp/pcaa162] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2020] [Accepted: 12/05/2020] [Indexed: 05/11/2023]
Abstract
In autophagy, cytoplasmic components of eukaryotic cells are transported to lysosomes or the vacuole for degradation. Autophagy is involved in plant tolerance to the photooxidative stress caused by ultraviolet B (UVB) radiation, but its roles in plant adaptation to UVB damage have not been fully elucidated. Here, we characterized organellar behavior in UVB-damaged Arabidopsis (Arabidopsis thaliana) leaves and observed the occurrence of autophagic elimination of dysfunctional mitochondria, a process termed mitophagy. Notably, Arabidopsis plants blocked in autophagy displayed increased leaf chlorosis after a 1-h UVB exposure compared to wild-type plants. We visualized autophagosomes by labeling with a fluorescent protein-tagged autophagosome marker, AUTOPHAGY8 (ATG8), and found that a 1-h UVB treatment led to increased formation of autophagosomes and the active transport of mitochondria into the central vacuole. In atg mutant plants, the mitochondrial population increased in UVB-damaged leaves due to the cytoplasmic accumulation of fragmented, depolarized mitochondria. Furthermore, we observed that autophagy was involved in the removal of depolarized mitochondria when mitochondrial function was disrupted by mutation of the FRIENDLY gene, which is required for proper mitochondrial distribution. Therefore, autophagy of mitochondria functions in response to mitochondrion-specific dysfunction as well as UVB damage. Together, these results indicate that autophagy is centrally involved in mitochondrial quality control in Arabidopsis leaves.
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Affiliation(s)
- Sakuya Nakamura
- Center for Sustainable Resource Science (CSRS), RIKEN, Wako, 351-0198 Japan
| | - Shinya Hagihara
- Center for Sustainable Resource Science (CSRS), RIKEN, Wako, 351-0198 Japan
| | - Kohei Otomo
- Exploratory Research Center on Life and Living Systems (ExCELLs), National Institute of Natural Sciences, Okazaki, 444-8787 Japan
- National Institute for Physiological Sciences, National Institutes of Natural Sciences, Okazaki, 444-8787 Japan
- Department of Physiological Sciences, The Graduate University for Advanced Study (SOKENDAI), Hayama, 240-0193 Japan
- Research Institute for Electronic Science, Hokkaido University, Sapporo, 001-0020 Japan
| | - Hiroyuki Ishida
- Department of Applied Plant Science, Graduate School of Agricultural Sciences, Tohoku University, Sendai, 980-0845, Japan
| | - Jun Hidema
- Department of Molecular and Chemical Life Sciences, Graduate School of Life Sciences, Tohoku University, Sendai, 980-8577, Japan
| | - Tomomi Nemoto
- Exploratory Research Center on Life and Living Systems (ExCELLs), National Institute of Natural Sciences, Okazaki, 444-8787 Japan
- National Institute for Physiological Sciences, National Institutes of Natural Sciences, Okazaki, 444-8787 Japan
- Department of Physiological Sciences, The Graduate University for Advanced Study (SOKENDAI), Hayama, 240-0193 Japan
- Research Institute for Electronic Science, Hokkaido University, Sapporo, 001-0020 Japan
| | - Masanori Izumi
- Center for Sustainable Resource Science (CSRS), RIKEN, Wako, 351-0198 Japan
- PRESTO, Japan Science and Technology Agency, Kawaguchi, 322-0012 Japan
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