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Wang Y, Shirakawa M, Ito T. Arrest, Senescence and Death of Shoot Apical Stem Cells in Arabidopsis thaliana. Plant Cell Physiol 2023; 64:284-290. [PMID: 36331512 DOI: 10.1093/pcp/pcac155] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2022] [Revised: 10/28/2022] [Accepted: 11/04/2022] [Indexed: 06/16/2023]
Abstract
Shoot stem cells act as the source of the aboveground parts of flowering plants. A precise regulatory basis is required to ensure that plant stem cells show the right status during the stages of proliferation, senescence and cell death. Over the past few decades, the genetic circuits controlling stem cell fate, including the regulatory pathways of establishment, maintenance and differentiation, have been largely revealed. However, the morphological changes and molecular mechanisms of the final stages of stem cells, which are represented by senescence and cell death, have been less studied. The senescence and death of shoot stem cells are under the control of a complex series of pathways that integrate multiple internal and external signals. Given the crucial roles of shoot stem cells in influencing plant longevity and crop yields, researchers have attempted to uncover details of stem cell senescence and death. Recent studies indicate that stem cell activity arrest is controlled by the FRUITFULL-APETALA2 pathway and the plant hormones auxin and cytokinin, while the features of senescent and dead shoot apical stem cells have also been described, with dynamic changes in reactive oxygen species implicated in stem cell death. In this review, we highlight the recent breakthroughs that have enriched our understanding of senescence and cell death processes in plant stem cells.
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Affiliation(s)
- Yukun Wang
- Guangdong Provincial Key Laboratory of Utilization and Conservation of Food and Medicinal Resources in Northern Region, Shaoguan University, Shaoguan 512005, China
- Henry Fok School of Biology and Agriculture, Shaoguan University, Shaoguan 512005, China
| | - Makoto Shirakawa
- Graduate School of Science and Technology, Nara Institute of Science and Technology, 8916-5 Takayama-cho, Ikoma 630-0192 Japan
| | - Toshiro Ito
- Graduate School of Science and Technology, Nara Institute of Science and Technology, 8916-5 Takayama-cho, Ikoma 630-0192 Japan
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Hao C, Yang Y, Du J, Deng XW, Li L. The PCY-SAG14 phytocyanin module regulated by PIFs and miR408 promotes dark-induced leaf senescence in Arabidopsis. Proc Natl Acad Sci U S A 2022; 119:e2116623119. [PMID: 35022242 PMCID: PMC8784109 DOI: 10.1073/pnas.2116623119] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Accepted: 12/08/2021] [Indexed: 11/21/2022] Open
Abstract
Leaf senescence is a critical process in plants and has a direct impact on many important agronomic traits. Despite decades of research on senescence-altered mutants via forward genetics and functional assessment of senescence-associated genes (SAGs) via reverse genetics, the senescence signal and the molecular mechanism that perceives and transduces the signal remain elusive. Here, using dark-induced senescence (DIS) of Arabidopsis leaf as the experimental system, we show that exogenous copper induces the senescence syndrome and transcriptomic changes in light-grown plants parallel to those in DIS. By profiling the transcriptomes and tracking the subcellular copper distribution, we found that reciprocal regulation of plastocyanin, the thylakoid lumen mobile electron carrier in the Z scheme of photosynthetic electron transport, and SAG14 and plantacyanin (PCY), a pair of interacting small blue copper proteins located on the endomembrane, is a common thread in different leaf senescence scenarios, including DIS. Genetic and molecular experiments confirmed that the PCY-SAG14 module is necessary and sufficient for promoting DIS. We also found that the PCY-SAG14 module is repressed by a conserved microRNA, miR408, which in turn is repressed by phytochrome interacting factor 3/4/5 (PIF3/4/5), the key trio of transcription factors promoting DIS. Together, these findings indicate that intracellular copper redistribution mediated by PCY-SAG14 has a regulatory role in DIS. Further deciphering the copper homeostasis mechanism and its interaction with other senescence-regulating pathways should provide insights into our understanding of the fundamental question of how plants age.
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Affiliation(s)
- Chen Hao
- State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Beijing 100871, China
| | - Yanzhi Yang
- School of Advanced Agricultural Sciences, Peking University, Beijing 100871, China
| | - Jianmei Du
- Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China
| | - Xing Wang Deng
- School of Advanced Agricultural Sciences, Peking University, Beijing 100871, China;
- Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China
| | - Lei Li
- State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Beijing 100871, China;
- School of Advanced Agricultural Sciences, Peking University, Beijing 100871, China
- Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China
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3
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Karia P, Yoshioka K, Moeder W. Multiple phosphorylation events of the mitochondrial membrane protein TTM1 regulate cell death during senescence. Plant J 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] [What about the content of this article? (0)] [Affiliation(s)] [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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Yu Y, Qi Y, Xu J, Dai X, Chen J, Dong CH, Xiang F. Arabidopsis WRKY71 regulates ethylene-mediated leaf senescence by directly activating EIN2, ORE1 and ACS2 genes. Plant J 2021; 107:1819-1836. [PMID: 34296474 DOI: 10.1111/tpj.15433] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Revised: 07/15/2021] [Accepted: 07/16/2021] [Indexed: 05/13/2023]
Abstract
Leaf senescence is a pivotal step in the last stage of the plant life cycle and is influenced by various external and endogenous cues. A series of reports have indicated the involvement of the WRKY transcription factors in regulating leaf senescence, but the molecular mechanisms and signaling pathways remain largely unclear. Here we provide evidence demonstrating that WRKY71 acts as a positive regulator of leaf senescence in Arabidopsis. WRKY71-1D, an overexpressor of WRKY71, exhibited early leaf senescence, while wrky71-1, the WRKY71 loss-of-function mutant, displayed delayed leaf senescence. Accordingly, a set of senescence-associated genes (SAGs) were substantially elevated in WRKY71-1D but markedly decreased in wrky71-1. Chromatin immunoprecipitation assays indicated that WRKY71 can bind directly to the promoters of SAG13 and SAG201. Transcriptome analysis suggested that WRKY71 might mediate multiple cues to accelerate leaf senescence, such as abiotic stresses, dark and ethylene. WRKY71 was ethylene inducible, and treatment with the ethylene precursor 1-amino-cyclopropane-1-carboxylic acid enhanced leaf senescence in WRKY71-1D but caused only a marginal delay in leaf senescence in wrky71-1. In vitro and in vivo assays demonstrated that WRKY71 can directly regulate ETHYLENE INSENSITIVE2 (EIN2) and ORESARA1 (ORE1), genes of the ethylene signaling pathway. Consistently, leaf senescence of WRKY71-1D was obviously retarded in the ein2-5 and nac2-1 mutants. Moreover, WRKY71 was also proved to interact with ACS2 in vitro and in vivo. Treatment with AgNO3 and aminoethoxyvinylglycine and acs2-1 could greatly arrest the leaf senescence of WRKY71-1D. In conclusion, our data revealed that WRKY71 mediates ethylene signaling and synthesis to hasten leaf senescence in Arabidopsis.
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Affiliation(s)
- Yanchong Yu
- Shandong Key Laboratory of Plant Biotechnology, College of Life Sciences, Qingdao Agricultural University, Qingdao, 266109, China
| | - Yanan Qi
- Shandong Key Laboratory of Plant Biotechnology, College of Life Sciences, Qingdao Agricultural University, Qingdao, 266109, China
| | - Jinpeng Xu
- Shandong Key Laboratory of Plant Biotechnology, College of Life Sciences, Qingdao Agricultural University, Qingdao, 266109, China
| | - Xuehuan Dai
- The Key Laboratory of Plant Development and Environmental Adaptation Biology, Ministry of Education, School of Life Sciences, Shandong University, Qingdao, 266237, China
| | - Jiacai Chen
- Shandong Key Laboratory of Plant Biotechnology, College of Life Sciences, Qingdao Agricultural University, Qingdao, 266109, China
| | - Chun-Hai Dong
- Shandong Key Laboratory of Plant Biotechnology, College of Life Sciences, Qingdao Agricultural University, Qingdao, 266109, China
| | - Fengning Xiang
- The Key Laboratory of Plant Development and Environmental Adaptation Biology, Ministry of Education, School of Life Sciences, Shandong University, Qingdao, 266237, China
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Minorsky PV. On the Inside. Plant Physiol 2021; 186:1747-1749. [PMID: 35237806 PMCID: PMC8331163 DOI: 10.1093/plphys/kiab265] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Accepted: 06/05/2021] [Indexed: 06/14/2023]
Affiliation(s)
- Peter V Minorsky
- School of Health and Natural Sciences, Mercy College, Dobbs Ferry, New York, USA
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