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Lemke MD, Abate AN, Woodson JD. Investigating the mechanism of chloroplast singlet oxygen signaling in the Arabidopsis thaliana accelerated cell death 2 mutant. PLANT SIGNALING & BEHAVIOR 2024; 19:2347783. [PMID: 38699898 PMCID: PMC11073415 DOI: 10.1080/15592324.2024.2347783] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2024] [Accepted: 04/19/2024] [Indexed: 05/05/2024]
Abstract
As sessile organisms, plants have evolved complex signaling mechanisms to sense stress and acclimate. This includes the use of reactive oxygen species (ROS) generated during dysfunctional photosynthesis to initiate signaling. One such ROS, singlet oxygen (1O2), can trigger retrograde signaling, chloroplast degradation, and programmed cell death. However, the signaling mechanisms are largely unknown. Several proteins (e.g. PUB4, OXI1, EX1) are proposed to play signaling roles across three Arabidopsis thaliana mutants that conditionally accumulate chloroplast 1O2 (fluorescent in blue light (flu), chlorina 1 (ch1), and plastid ferrochelatase 2 (fc2)). We previously demonstrated that these mutants reveal at least two chloroplast 1O2 signaling pathways (represented by flu and fc2/ch1). Here, we test if the 1O2-accumulating lesion mimic mutant, accelerated cell death 2 (acd2), also utilizes these pathways. The pub4-6 allele delayed lesion formation in acd2 and restored photosynthetic efficiency and biomass. Conversely, an oxi1 mutation had no measurable effect on these phenotypes. acd2 mutants were not sensitive to excess light (EL) stress, yet pub4-6 and oxi1 both conferred EL tolerance within the acd2 background, suggesting that EL-induced 1O2 signaling pathways are independent from spontaneous lesion formation. Thus, 1O2 signaling in acd2 may represent a third (partially overlapping) pathway to control cellular degradation.
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Affiliation(s)
- Matthew D. Lemke
- The School of Plant Sciences, University of Arizona, Tucson, AZ, USA
| | - Alexa N. Abate
- The School of Plant Sciences, University of Arizona, Tucson, AZ, USA
| | - Jesse D. Woodson
- The School of Plant Sciences, University of Arizona, Tucson, AZ, USA
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2
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Rai S, Lemke MD, Arias AM, Mendez MFG, Dehesh K, Woodson JD. Plant U-Box 4 regulates chloroplast stress signaling and programmed cell death via Salicylic acid modulation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.13.593788. [PMID: 38798329 PMCID: PMC11118471 DOI: 10.1101/2024.05.13.593788] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2024]
Abstract
In response to environmental stress, chloroplasts generate reactive oxygen species, including singlet oxygen ( 1 O 2 ), which regulates nuclear gene expression (retrograde signaling), chloroplast turnover, and programmed cell death (PCD). Yet, the central signaling mechanisms and downstream responses remain poorly understood. The Arabidopsis thaliana plastid ferrochelatase two ( fc2 ) mutant conditionally accumulates 1 O 2 and involves Plant U-Box 4 (PUB4), a cytoplasmic E3 ubiquitin ligase, in propagating these signals. To gain insights into 1 O 2 signaling pathways, we compared transcriptomes of fc2 and fc2 pub4 mutants. The accumulation of 1 O 2 in fc2 plants broadly repressed genes involved in chloroplast function and photosynthesis, while 1 O 2 induced genes and transcription factors involved in abiotic and biotic stress, the biosynthesis of jasmonic acid (JA), and Salicylic acid (SA). Elevated JA and SA levels were observed in stressed fc2 plants, but were not responsible for PCD. pub4 reversed the majority of 1 O 2 -induced gene expression in fc2 and reduced the JA content, but maintained elevated levels of SA even in the absence of 1 O 2 stress. Reducing SA levels in fc2 pub4 restored 1 O 2 signaling and light sensitivity. Together, this work demonstrates that SA plays a protective role during photo-oxidative stress and that PUB4 mediates 1 O 2 signaling by modulating its levels.
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Wu S, Hu C, Zhu C, Fan Y, Zhou J, Xia X, Shi K, Zhou Y, Foyer CH, Yu J. The MYC2-PUB22-JAZ4 module plays a crucial role in jasmonate signaling in tomato. MOLECULAR PLANT 2024; 17:598-613. [PMID: 38341757 DOI: 10.1016/j.molp.2024.02.006] [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: 08/03/2023] [Revised: 12/06/2023] [Accepted: 02/06/2024] [Indexed: 02/13/2024]
Abstract
Jasmonates (JAs), a class of lipid-derived stress hormones, play a crucial role across an array of plant physiological processes and stress responses. Although JA signaling is thought to rely predominantly on the degradation of specific JAZ proteins by SCFCOI1, it remains unclear whether other pathways are involved in the regulation of JAZ protein stability. Here, we report that PUB22, a plant U-box type E3 ubiquitin ligase, plays a critical role in the regulation of plant resistance against Helicoverpa armigera and other JA responses in tomato. Whereas COI1 physically interacts with JAZ1/2/5/7, PUB22 physically interacts with JAZ1/3/4/6. PUB22 ubiquitinates JAZ4 to promote its degradation via the 26S proteasome pathway. Importantly, we observed that pub22 mutants showreduced resistance to H. armigera, whereas jaz4 single mutants and jaz1 jaz3 jaz4 jaz6 quadruple mutants have enhanced resistance. The hypersensitivity of pub22 mutants to herbivores could be partially rescued by JAZ4 mutation. Moreover, we found that expression of PUB22 can be transcriptionally activated by MYC2, thus forming a positive feedback circuit in JA signaling. We noticed that the PUB22-JAZ4 module also regulates other JA responses, including defense against B. cinerea, inhibition of root elongation, and anthocyanin accumulation. Taken together, these results indicate that PUB22 plays a crucial role in plant growth and defense responses, together with COI1-regulated JA signaling, by targeting specific JAZs.
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Affiliation(s)
- Shaofang Wu
- Department of Horticulture, Zijingang Campus, Zhejiang University, Hangzhou 310058, China
| | - Chaoyi Hu
- Department of Horticulture, Zijingang Campus, Zhejiang University, Hangzhou 310058, China; Hainan Institute, Zhejiang University, Yazhou Bay Science and Technology City, Sanya 572025, China
| | - Changan Zhu
- Department of Horticulture, Zijingang Campus, Zhejiang University, Hangzhou 310058, China
| | - Yanfen Fan
- Department of Horticulture, Zijingang Campus, Zhejiang University, Hangzhou 310058, China; College of Horticulture, Northwest Agriculture & Forestry University, Xianyang 712100, China
| | - Jie Zhou
- Department of Horticulture, Zijingang Campus, Zhejiang University, Hangzhou 310058, China
| | - Xiaojia Xia
- Department of Horticulture, Zijingang Campus, Zhejiang University, Hangzhou 310058, China
| | - Kai Shi
- Department of Horticulture, Zijingang Campus, Zhejiang University, Hangzhou 310058, China
| | - Yanhong Zhou
- Department of Horticulture, Zijingang Campus, Zhejiang University, Hangzhou 310058, China
| | - Christine H Foyer
- School of Biosciences, College of Life and Environmental Sciences, University of Birmingham, Edgbaston B15 2TT, UK
| | - Jingquan Yu
- Department of Horticulture, Zijingang Campus, Zhejiang University, Hangzhou 310058, China; Hainan Institute, Zhejiang University, Yazhou Bay Science and Technology City, Sanya 572025, China; Key Laboratory of Horticultural Plants Growth and Development, Agricultural Ministry of China, Zhejiang University, Hangzhou 310058, China.
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Zhou T, Sheng B, Gao H, Nie X, Sun H, Xing B, Wu L, Zhao D, Wu J, Li C. Effect of fat concentration on protein digestibility of Chinese sausage. Food Res Int 2024; 177:113922. [PMID: 38225153 DOI: 10.1016/j.foodres.2023.113922] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2023] [Revised: 12/12/2023] [Accepted: 12/21/2023] [Indexed: 01/17/2024]
Abstract
Chinese sausage is a popular traditional Chinese meat product, but its high-fat content makes consumers hesitant. The purpose of this study is to compare the nutritional differences of Chinese sausages with different fermentation times (0, 10, 20, 30 d) and fat content (the initial content was 11.59% and 20.14%) during digestion. The comparison of digestion degree, protein structure, and peptide composition between different sausages were studied through in vitro simulated digestion. Chinese sausages with high-fat content had higher α-helix, β-turn, and random coil, making them easier to digest. The fermentation process made this phenomenon more pronounced. The high-fat sausage fermented for 10 d showed the highest release of primary amino acids (about 9.5%), which was about 3.5% higher than the low-fat sausage under the same conditions. The results of peptidomics confirmed the relevant conclusions. After gastric digestion, the types of peptides in the digestive fluid of high-fat sausages were generally more than those in low-fat sausages, while after intestinal digestion, the opposite results were observed. The type of peptide reached its peak after fermentation for 20 d. These findings are of obvious significance for selecting the appropriate fermentation time and fat content of Chinese sausages.
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Affiliation(s)
- Tianming Zhou
- National key Laboratory of Meat Quality Control and Cultured Meat Development, Ministry of Science and Technology, Key Laboratory of Meat Processing, Ministry of Agriculture and Rural Affairs, Jiangsu Provincial Collaborative Innovative Center of Meat Production, Processing and Quality Control, College of Food Science and Technology, Nanjing Agricultural University, Nanjing, 210095, PR China
| | - Bulei Sheng
- Key Laboratory of Agricultural Product Fine Processing and Resource Utilization, Ministry of Agriculture and Rural Affairs, Anhui Engineering Research Center for High Value Utilization of Characteristic Agricultural Products, College of Tea & Food Science and Technology, Anhui Agricultural University, Hefei, 230036, PR China
| | - Haotian Gao
- National key Laboratory of Meat Quality Control and Cultured Meat Development, Ministry of Science and Technology, Key Laboratory of Meat Processing, Ministry of Agriculture and Rural Affairs, Jiangsu Provincial Collaborative Innovative Center of Meat Production, Processing and Quality Control, College of Food Science and Technology, Nanjing Agricultural University, Nanjing, 210095, PR China
| | - Xiaonan Nie
- National key Laboratory of Meat Quality Control and Cultured Meat Development, Ministry of Science and Technology, Key Laboratory of Meat Processing, Ministry of Agriculture and Rural Affairs, Jiangsu Provincial Collaborative Innovative Center of Meat Production, Processing and Quality Control, College of Food Science and Technology, Nanjing Agricultural University, Nanjing, 210095, PR China
| | - Haojie Sun
- National key Laboratory of Meat Quality Control and Cultured Meat Development, Ministry of Science and Technology, Key Laboratory of Meat Processing, Ministry of Agriculture and Rural Affairs, Jiangsu Provincial Collaborative Innovative Center of Meat Production, Processing and Quality Control, College of Food Science and Technology, Nanjing Agricultural University, Nanjing, 210095, PR China
| | - Baofang Xing
- National key Laboratory of Meat Quality Control and Cultured Meat Development, Ministry of Science and Technology, Key Laboratory of Meat Processing, Ministry of Agriculture and Rural Affairs, Jiangsu Provincial Collaborative Innovative Center of Meat Production, Processing and Quality Control, College of Food Science and Technology, Nanjing Agricultural University, Nanjing, 210095, PR China
| | - Longxia Wu
- National key Laboratory of Meat Quality Control and Cultured Meat Development, Ministry of Science and Technology, Key Laboratory of Meat Processing, Ministry of Agriculture and Rural Affairs, Jiangsu Provincial Collaborative Innovative Center of Meat Production, Processing and Quality Control, College of Food Science and Technology, Nanjing Agricultural University, Nanjing, 210095, PR China
| | - Di Zhao
- National key Laboratory of Meat Quality Control and Cultured Meat Development, Ministry of Science and Technology, Key Laboratory of Meat Processing, Ministry of Agriculture and Rural Affairs, Jiangsu Provincial Collaborative Innovative Center of Meat Production, Processing and Quality Control, College of Food Science and Technology, Nanjing Agricultural University, Nanjing, 210095, PR China.
| | - Juqing Wu
- National key Laboratory of Meat Quality Control and Cultured Meat Development, Ministry of Science and Technology, Key Laboratory of Meat Processing, Ministry of Agriculture and Rural Affairs, Jiangsu Provincial Collaborative Innovative Center of Meat Production, Processing and Quality Control, College of Food Science and Technology, Nanjing Agricultural University, Nanjing, 210095, PR China.
| | - Chunbao Li
- National key Laboratory of Meat Quality Control and Cultured Meat Development, Ministry of Science and Technology, Key Laboratory of Meat Processing, Ministry of Agriculture and Rural Affairs, Jiangsu Provincial Collaborative Innovative Center of Meat Production, Processing and Quality Control, College of Food Science and Technology, Nanjing Agricultural University, Nanjing, 210095, PR China
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Lemke MD, Woodson JD. A genetic screen for dominant chloroplast reactive oxygen species signaling mutants reveals life stage-specific singlet oxygen signaling networks. FRONTIERS IN PLANT SCIENCE 2024; 14:1331346. [PMID: 38273946 PMCID: PMC10809407 DOI: 10.3389/fpls.2023.1331346] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Accepted: 12/18/2023] [Indexed: 01/27/2024]
Abstract
Introduction Plants employ intricate molecular mechanisms to respond to abiotic stresses, which often lead to the accumulation of reactive oxygen species (ROS) within organelles such as chloroplasts. Such ROS can produce stress signals that regulate cellular response mechanisms. One ROS, singlet oxygen (1O2), is predominantly produced in the chloroplast during photosynthesis and can trigger chloroplast degradation, programmed cell death (PCD), and retrograde (organelle-to-nucleus) signaling. However, little is known about the molecular mechanisms involved in these signaling pathways or how many different signaling 1O2 pathways may exist. Methods The Arabidopsis thaliana plastid ferrochelatase two (fc2) mutant conditionally accumulates chloroplast 1O2, making fc2 a valuable genetic system for studying chloroplast 1O2-initiated signaling. Here, we have used activation tagging in a new forward genetic screen to identify eight dominant fc2 activation-tagged (fas) mutations that suppress chloroplast 1O2-initiated PCD. Results While 1O2-triggered PCD is blocked in all fc2 fas mutants in the adult stage, such cellular degradation in the seedling stage is blocked in only two mutants. This differential blocking of PCD suggests that life-stage-specific 1O2-response pathways exist. In addition to PCD, fas mutations generally reduce 1O2-induced retrograde signals. Furthermore, fas mutants have enhanced tolerance to excess light, a natural mechanism to produce chloroplast 1O2. However, general abiotic stress tolerance was only observed in one fc2 fas mutant (fc2 fas2). Together, this suggests that plants can employ general stress tolerance mechanisms to overcome 1O2 production but that this screen was mostly specific to 1O2 signaling. We also observed that salicylic acid (SA) and jasmonate (JA) stress hormone response marker genes were induced in 1O2-stressed fc2 and generally reduced by fas mutations, suggesting that SA and JA signaling is correlated with active 1O2 signaling and PCD. Discussion Together, this work highlights the complexity of 1O2 signaling by demonstrating that multiple pathways may exist and introduces a suite of new 1O2 signaling mutants to investigate the mechanisms controlling chloroplast-initiated degradation, PCD, and retrograde signaling.
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Affiliation(s)
| | - Jesse D. Woodson
- The School of Plant Sciences, University of Arizona, Tucson, AZ, United States
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Liu K, Shi L, Luo H, Zhang K, Liu J, Qiu S, Li X, He S, Liu Z. Ralstonia solanacearum effector RipAK suppresses homodimerization of the host transcription factor ERF098 to enhance susceptibility and the sensitivity of pepper plants to dehydration. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2024; 117:121-144. [PMID: 37738430 DOI: 10.1111/tpj.16479] [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: 03/09/2023] [Revised: 08/03/2023] [Accepted: 08/25/2023] [Indexed: 09/24/2023]
Abstract
Plants have evolved a sophisticated immune system to defend against invasion by pathogens. In response, pathogens deploy copious effectors to evade the immune responses. However, the molecular mechanisms used by pathogen effectors to suppress plant immunity remain unclear. Herein, we report that an effector secreted by Ralstonia solanacearum, RipAK, modulates the transcriptional activity of the ethylene-responsive factor ERF098 to suppress immunity and dehydration tolerance, which causes bacterial wilt in pepper (Capsicum annuum L.) plants. Silencing ERF098 enhances the resistance of pepper plants to R. solanacearum infection not only by inhibiting the host colonization of R. solanacearum but also by increasing the immunity and tolerance of pepper plants to dehydration and including the closure of stomata to reduce the loss of water in an abscisic acid signal-dependent manner. In contrast, the ectopic expression of ERF098 in Nicotiana benthamiana enhances wilt disease. We also show that RipAK targets and inhibits the ERF098 homodimerization to repress the expression of salicylic acid-dependent PR1 and dehydration tolerance-related OSR1 and OSM1 by cis-elements in their promoters. Taken together, our study reveals a regulatory mechanism used by the R. solanacearum effector RipAK to increase virulence by specifically inhibiting the homodimerization of ERF098 and reprogramming the transcription of PR1, OSR1, and OSM1 to boost susceptibility and dehydration sensitivity. Thus, our study sheds light on a previously unidentified strategy by which a pathogen simultaneously suppresses plant immunity and tolerance to dehydration by secreting an effector to interfere with the activity of a transcription factor and manipulate plant transcriptional programs.
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Affiliation(s)
- Kaisheng Liu
- Key Laboratory of Applied Genetics of Universities in Fujian Province, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
- Key Laboratory of Ministry of Education for Genetics, Breeding and Multiple Utilization of Crops, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
- College of Agriculture, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Lanping Shi
- Key Laboratory of Applied Genetics of Universities in Fujian Province, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
- Key Laboratory of Ministry of Education for Genetics, Breeding and Multiple Utilization of Crops, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
- College of Agriculture, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Hongli Luo
- Key Laboratory of Applied Genetics of Universities in Fujian Province, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
- Key Laboratory of Ministry of Education for Genetics, Breeding and Multiple Utilization of Crops, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
- College of Agriculture, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Kan Zhang
- Key Laboratory of Applied Genetics of Universities in Fujian Province, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
- Key Laboratory of Ministry of Education for Genetics, Breeding and Multiple Utilization of Crops, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
- College of Agriculture, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Jianxin Liu
- Key Laboratory of Applied Genetics of Universities in Fujian Province, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
- Key Laboratory of Ministry of Education for Genetics, Breeding and Multiple Utilization of Crops, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
- College of Agriculture, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Shanshan Qiu
- Key Laboratory of Applied Genetics of Universities in Fujian Province, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
- Key Laboratory of Ministry of Education for Genetics, Breeding and Multiple Utilization of Crops, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
- College of Agriculture, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Xia Li
- Key Laboratory of Applied Genetics of Universities in Fujian Province, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
- Key Laboratory of Ministry of Education for Genetics, Breeding and Multiple Utilization of Crops, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
- College of Agriculture, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Shuilin He
- Key Laboratory of Applied Genetics of Universities in Fujian Province, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
- Key Laboratory of Ministry of Education for Genetics, Breeding and Multiple Utilization of Crops, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
- College of Agriculture, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Zhiqin Liu
- Key Laboratory of Applied Genetics of Universities in Fujian Province, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
- Key Laboratory of Ministry of Education for Genetics, Breeding and Multiple Utilization of Crops, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
- College of Agriculture, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
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Wei J, Sun W, Zheng X, Qiu S, Jiao S, Babilonia K, Koiwa H, He P, Shan L, Sun W, Cui F. Arabidopsis RNA polymerase II C-terminal domain phosphatase-like 1 targets mitogen-activated protein kinase cascades to suppress plant immunity. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2023; 65:2380-2394. [PMID: 37534615 DOI: 10.1111/jipb.13551] [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: 03/21/2023] [Accepted: 07/31/2023] [Indexed: 08/04/2023]
Abstract
Mitogen-activated protein kinase (MAPK) cascades play pivotal roles in plant defense against phytopathogens downstream of immune receptor complexes. The amplitude and duration of MAPK activation must be strictly controlled, but the underlying mechanism remains unclear. Here, we identified Arabidopsis CPL1 (C-terminal domain phosphatase-like 1) as a negative regulator of microbe-associated molecular pattern (MAMP)-triggered immunity via a forward-genetic screen. Disruption of CPL1 significantly enhanced plant resistance to Pseudomonas pathogens induced by the bacterial peptide flg22. Furthermore, flg22-induced MPK3/MPK4/MPK6 phosphorylation was dramatically elevated in cpl1 mutants but severely impaired in CPL1 overexpression lines, suggesting that CPL1 might interfere with flg22-induced MAPK activation. Indeed, CPL1 directly interacted with MPK3 and MPK6, as well as the upstream MKK4 and MKK5. A firefly luciferase-based complementation assay indicated that the interaction between MKK4/MKK5 and MPK3/MPK6 was significantly reduced in the presence of CPL1. These results suggest that CPL1 plays a novel regulatory role in suppressing MAMP-induced MAPK cascade activation and MAMP-triggered immunity to bacterial pathogens.
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Affiliation(s)
- Junjun Wei
- Department of Plant Pathology and the Ministry of Agriculture Key Laboratory of Pest Monitoring and Green Management, China Agricultural University, Beijing, 100193, China
| | - Wei Sun
- Department of Plant Pathology and the Ministry of Agriculture Key Laboratory of Pest Monitoring and Green Management, China Agricultural University, Beijing, 100193, China
| | - Xinhang Zheng
- Department of Plant Pathology and the Ministry of Agriculture Key Laboratory of Pest Monitoring and Green Management, China Agricultural University, Beijing, 100193, China
| | - Shanshan Qiu
- Department of Plant Pathology and the Ministry of Agriculture Key Laboratory of Pest Monitoring and Green Management, China Agricultural University, Beijing, 100193, China
| | - Shuangyu Jiao
- Department of Plant Pathology and the Ministry of Agriculture Key Laboratory of Pest Monitoring and Green Management, China Agricultural University, Beijing, 100193, China
| | - Kevin Babilonia
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX, 77843, USA
| | - Hisashi Koiwa
- Department of Horticultural Sciences, Texas A&M University, College Station, TX, 77843, USA
| | - Ping He
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX, 77843, USA
| | - Libo Shan
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX, 77843, USA
| | - Wenxian Sun
- Department of Plant Pathology and the Ministry of Agriculture Key Laboratory of Pest Monitoring and Green Management, China Agricultural University, Beijing, 100193, China
| | - Fuhao Cui
- Department of Plant Pathology and the Ministry of Agriculture Key Laboratory of Pest Monitoring and Green Management, China Agricultural University, Beijing, 100193, China
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Bai J, Zhou Y, Sun J, Chen K, Han Y, Wang R, Zou Y, Du M, Lu D. BIK1 protein homeostasis is maintained by the interplay of different ubiquitin ligases in immune signaling. Nat Commun 2023; 14:4624. [PMID: 37532719 PMCID: PMC10397244 DOI: 10.1038/s41467-023-40364-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Accepted: 07/25/2023] [Indexed: 08/04/2023] Open
Abstract
Pathogen-associated molecular patterns (PAMPs) trigger plant innate immunity that acts as the first line of inducible defense against pathogen infection. A receptor-like cytoplasmic kinase BOTRYTIS-INDUCED KINASE 1 (BIK1) functions as a signaling hub immediately downstream of multiple pattern recognition receptors (PRRs). It is known that PLANT U-BOX PROTEIN 25 (PUB25) and PUB26 ubiquitinate BIK1 and mediate BIK1 degradation. However, how BIK1 homeostasis is maintained is not fully understood. Here, we show that two closely related ubiquitin ligases, RING DOMAIN LIGASE 1 (RGLG1) and RGLG2, preferentially associate with the hypo-phosphorylated BIK1 and promote the association of BIK1 with the co-receptor for several PRRs, BRI1-ASSOCIATED RECEPTOR KINASE1 (BAK1). PUB25 interacts with RGLG2 and mediates its degradation. In turn, RGLG2 represses the ubiquitin ligase activity of PUB25. RGLG1/2 suppress PUB25-mediated BIK1 degradation, promote BIK1 protein accumulation, and positively regulate immune signaling in a ubiquitin ligase activity-dependent manner. Our work reveals how BIK1 homeostasis is maintained by the interplay of different ubiquitin ligases.
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Affiliation(s)
- Jiaojiao Bai
- State Key Laboratory of Plant Genomics, Center for Agricultural Resources Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Shijiazhuang, Hebei, 050021, China
- Joint Center for Single Cell Biology, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, 200240, China
- College of Pharmacy and Life Science, Jiujiang University, Jiujiang, Jiangxi, 332000, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Yuanyuan Zhou
- State Key Laboratory of Plant Genomics, Center for Agricultural Resources Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Shijiazhuang, Hebei, 050021, China
- Joint Center for Single Cell Biology, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, 200240, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Jianhang Sun
- State Key Laboratory of Plant Genomics, Center for Agricultural Resources Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Shijiazhuang, Hebei, 050021, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Kexin Chen
- State Key Laboratory of Plant Genomics, Center for Agricultural Resources Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Shijiazhuang, Hebei, 050021, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Yufang Han
- State Key Laboratory of Plant Genomics, Center for Agricultural Resources Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Shijiazhuang, Hebei, 050021, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Ranran Wang
- State Key Laboratory of Plant Genomics, Center for Agricultural Resources Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Shijiazhuang, Hebei, 050021, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Yanmin Zou
- State Key Laboratory of Plant Genomics, Center for Agricultural Resources Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Shijiazhuang, Hebei, 050021, China
| | - Mingshuo Du
- State Key Laboratory of Plant Genomics, Center for Agricultural Resources Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Shijiazhuang, Hebei, 050021, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Dongping Lu
- Joint Center for Single Cell Biology, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, 200240, China.
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Li Z, Li S, Jin D, Yang Y, Pu Z, Han X, Hu Y, Jiang Y. U-box E3 ubiquitin ligase PUB8 attenuates abscisic acid responses during early seedling growth. PLANT PHYSIOLOGY 2023; 191:2519-2533. [PMID: 36715300 PMCID: PMC10069885 DOI: 10.1093/plphys/kiad044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Accepted: 01/04/2023] [Indexed: 06/18/2023]
Abstract
ABSCISIC ACID-INSENSITIVE3 (ABI3) and ABI5 are 2 crucial transcription factors in abscisic acid (ABA) signaling, and their homeostasis at the protein level plays a decisive role in seed germination and subsequent seedling growth. Here, we found that PLANT U-BOX 8 (PUB8), a U-box E3 ubiquitin ligase, physically interacts with ABI3 and ABI5 and negatively regulates ABA responses during early Arabidopsis (Arabidopsis thaliana) seedling growth. Loss-of-function pub8 mutants were hypersensitive to ABA-inhibited cotyledon greening, while lines overexpressing PUB8 with low levels of ABI5 protein abundance were insensitive to ABA. Genetic analyses showed that ABI3 and ABI5 were required for the ABA-sensitive phenotype of pub8, indicating that PUB8 functions upstream of ABI3 and ABI5 to regulate ABA responses. Biochemical analyses showed that PUB8 can associate with ABI3 and ABI5 for degradation through the ubiquitin-mediated 26S proteasome pathway. Correspondingly, loss-of-function of PUB8 led to enhanced ABI3 and ABI5 stability, while overexpression of PUB8 impaired accumulation of ABI3 and ABI5 in planta. Further phenotypic analysis indicated that PUB8 compromised the function of ABI5 during early seedling growth. Taken together, our results reveal the regulatory role of PUB8 in modulating the early seedling growth by controlling the homeostasis of ABI3 and ABI5.
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Affiliation(s)
- Zhipeng Li
- CAS Key Laboratory of Tropical Plant Resources and Sustainable Use, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Kunming, Yunnan 650223, China
- State Key Laboratory for Conservation and Utilization of Bio-resources in Yunnan, Yunnan University, Kunming, Yunnan 650091, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Shaoqin Li
- CAS Key Laboratory of Tropical Plant Resources and Sustainable Use, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Kunming, Yunnan 650223, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Dongjie Jin
- CAS Key Laboratory of Tropical Plant Resources and Sustainable Use, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Kunming, Yunnan 650223, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yongping Yang
- CAS Key Laboratory of Tropical Plant Resources and Sustainable Use, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Kunming, Yunnan 650223, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Zhengyan Pu
- State Key Laboratory for Conservation and Utilization of Bio-resources in Yunnan, Yunnan University, Kunming, Yunnan 650091, China
| | - Xiao Han
- CAS Key Laboratory of Tropical Plant Resources and Sustainable Use, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Kunming, Yunnan 650223, China
- Center of Economic Botany, Core Botanical Gardens, Chinese Academy of Sciences, Kunming, Yunnan 650223, China
| | - Yanru Hu
- Author for correspondence: (Y.J.), (Y.H.)
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10
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Wang Y, Zhang H, Wang P, Zhong H, Liu W, Zhang S, Xiong L, Wu Y, Xia Y. Arabidopsis EXTRA-LARGE G PROTEIN 1 (XLG1) functions together with XLG2 and XLG3 in PAMP-triggered MAPK activation and immunity. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2023; 65:825-837. [PMID: 36250681 DOI: 10.1111/jipb.13391] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2022] [Accepted: 10/17/2022] [Indexed: 06/16/2023]
Abstract
Pattern-triggered immunity (PTI) is an essential strategy used by plants to deploy broad-spectrum resistance against pathogen attacks. Heterotrimeric G proteins have been reported to contribute to PTI. Of the three non-canonical EXTRA-LARGE G PROTEINs (XLGs) in Arabidopsis thaliana, XLG2 and XLG3 were shown to positively regulate immunity, but XLG1 was not considered to function in defense, based on the analysis of a weak xlg1 allele. In this study, we characterized the xlg1 xlg2 xlg3 triple knockout mutants generated from an xlg1 knockout allele. The strong xlg1 xlg2 xlg3 triple mutants compromised pathogen-associated molecular pattern (PAMP)-triggered activation of mitogen-activated protein kinases (MAPKs) and resistance to pathogen infection. The three XLGs interacted with MAPK cascade proteins involved in defense signaling, including the MAPK kinase kinases MAPKKK3 and MAPKKK5, the MAPK kinases MKK4 and MKK5, and the MAPKs MPK3 and MPK6. Expressing a constitutively active form of MKK4 restored MAPK activation and partially recovered the compromised disease resistance seen in the strong xlg1 xlg2 xlg3 triple mutant. Furthermore, mutations of all three XLGs largely restored the phenotype of the autoimmunity mutant bak1-interacting receptor-like kinase 1. Our study reveals that all three XLGs function redundantly in PAMP-triggered MAPK activation and plant immunity.
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Affiliation(s)
- Yiping Wang
- Department of Biology, Hong Kong Baptist University, Hong Kong, 999077, China
- Institute for Research and Continuing Education, Hong Kong Baptist University, Shen Zhen, 518057, China
| | - Hailei Zhang
- Department of Biology, Hong Kong Baptist University, Hong Kong, 999077, China
| | - Pengxi Wang
- Department of Biology, Hong Kong Baptist University, Hong Kong, 999077, China
| | - Huan Zhong
- Department of Biology, Hong Kong Baptist University, Hong Kong, 999077, China
| | - Wuzhen Liu
- Department of Biology, Hong Kong Baptist University, Hong Kong, 999077, China
| | - Shoudong Zhang
- Department of Biology, Hong Kong Baptist University, Hong Kong, 999077, China
| | - Liming Xiong
- Department of Biology, Hong Kong Baptist University, Hong Kong, 999077, China
| | - Yingying Wu
- Department of Biology, Hong Kong Baptist University, Hong Kong, 999077, China
| | - Yiji Xia
- Department of Biology, Hong Kong Baptist University, Hong Kong, 999077, China
- State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Hong Kong, 999077, China
- State Key Laboratory of Biological and Environmental Analysis, Hong Kong Baptist University, Hong Kong, 999077, China
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11
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Tano DW, Kozlowska MA, Easter RA, Woodson JD. Multiple pathways mediate chloroplast singlet oxygen stress signaling. PLANT MOLECULAR BIOLOGY 2023; 111:167-187. [PMID: 36266500 DOI: 10.1007/s11103-022-01319-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Accepted: 10/07/2022] [Indexed: 06/16/2023]
Abstract
Chloroplast singlet oxygen initiates multiple pathways to control chloroplast degradation, cell death, and nuclear gene expression. Chloroplasts can respond to stress and changes in the environment by producing reactive oxygen species (ROS). Aside from being cytotoxic, ROS also have signaling capabilities. For example, the ROS singlet oxygen (1O2) can initiate nuclear gene expression, chloroplast degradation, and cell death. To unveil the signaling mechanisms involved, researchers have used several 1O2-producing Arabidopsis thaliana mutants as genetic model systems, including plastid ferrochelatase two (fc2), fluorescent in blue light (flu), chlorina 1 (ch1), and accelerated cell death 2 (acd2). Here, we compare these 1O2-producing mutants to elucidate if they utilize one or more signaling pathways to control cell death and nuclear gene expression. Using publicly available transcriptomic data, we demonstrate fc2, flu, and ch1 share a core response to 1O2 accumulation, but maintain unique responses, potentially tailored to respond to their specific stresses. Subsequently, we used a genetic approach to determine if these mutants share 1O2 signaling pathways by testing the ability of genetic suppressors of one 1O2 producing mutant to suppress signaling in a different 1O2 producing mutant. Our genetic analyses revealed at least two different chloroplast 1O2 signaling pathways control cellular degradation: one specific to the flu mutant and one shared by fc2, ch1, and acd2 mutants, but with life-stage-specific (seedling vs. adult) features. Overall, this work reveals chloroplast stress signaling involving 1O2 is complex and may allow cells to finely tune their physiology to environmental inputs.
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Affiliation(s)
- David W Tano
- The School of Plant Sciences, University of Arizona, 1140 E, South Campus Drive, 303 Forbes Hall, Tucson, AZ, 85721-0036, USA
| | - Marta A Kozlowska
- The School of Plant Sciences, University of Arizona, 1140 E, South Campus Drive, 303 Forbes Hall, Tucson, AZ, 85721-0036, USA
| | - Robert A Easter
- The School of Plant Sciences, University of Arizona, 1140 E, South Campus Drive, 303 Forbes Hall, Tucson, AZ, 85721-0036, USA
| | - Jesse D Woodson
- The School of Plant Sciences, University of Arizona, 1140 E, South Campus Drive, 303 Forbes Hall, Tucson, AZ, 85721-0036, USA.
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12
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Yu G, Derkacheva M, Rufian JS, Brillada C, Kowarschik K, Jiang S, Derbyshire P, Ma M, DeFalco TA, Morcillo RJL, Stransfeld L, Wei Y, Zhou J, Menke FLH, Trujillo M, Zipfel C, Macho AP. The Arabidopsis E3 ubiquitin ligase PUB4 regulates BIK1 and is targeted by a bacterial type-III effector. EMBO J 2022; 41:e107257. [PMID: 36314733 PMCID: PMC9713774 DOI: 10.15252/embj.2020107257] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Revised: 09/26/2022] [Accepted: 10/07/2022] [Indexed: 12/03/2022] Open
Abstract
Plant immunity is tightly controlled by a complex and dynamic regulatory network, which ensures optimal activation upon detection of potential pathogens. Accordingly, each component of this network is a potential target for manipulation by pathogens. Here, we report that RipAC, a type III-secreted effector from the bacterial pathogen Ralstonia solanacearum, targets the plant E3 ubiquitin ligase PUB4 to inhibit pattern-triggered immunity (PTI). PUB4 plays a positive role in PTI by regulating the homeostasis of the central immune kinase BIK1. Before PAMP perception, PUB4 promotes the degradation of non-activated BIK1, while after PAMP perception, PUB4 contributes to the accumulation of activated BIK1. RipAC leads to BIK1 degradation, which correlates with its PTI-inhibitory activity. RipAC causes a reduction in pathogen-associated molecular pattern (PAMP)-induced PUB4 accumulation and phosphorylation. Our results shed light on the role played by PUB4 in immune regulation, and illustrate an indirect targeting of the immune signalling hub BIK1 by a bacterial effector.
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Affiliation(s)
- Gang Yu
- Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant SciencesChinese Academy of SciencesShanghaiChina
| | - Maria Derkacheva
- The Sainsbury LaboratoryUniversity of East Anglia, Norwich Research ParkNorwichUK
- Present address:
The Earlham InstituteNorwich Research ParkNorwichUK
| | - Jose S Rufian
- Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant SciencesChinese Academy of SciencesShanghaiChina
| | - Carla Brillada
- Faculty of Biology, Institute of Biology IIAlbert‐Ludwigs‐University FreiburgFreiburgGermany
| | | | - Shushu Jiang
- The Sainsbury LaboratoryUniversity of East Anglia, Norwich Research ParkNorwichUK
- Present address:
Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell ScienceChinese Academy of SciencesShanghaiChina
| | - Paul Derbyshire
- The Sainsbury LaboratoryUniversity of East Anglia, Norwich Research ParkNorwichUK
| | - Miaomiao Ma
- State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental BiologyChinese Academy of SciencesBeijingChina
| | - Thomas A DeFalco
- Institute of Plant and Microbial Biology, Zurich‐Basel Plant Science CenterUniversity of ZurichZurichSwitzerland
| | - Rafael J L Morcillo
- Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant SciencesChinese Academy of SciencesShanghaiChina
| | - Lena Stransfeld
- The Sainsbury LaboratoryUniversity of East Anglia, Norwich Research ParkNorwichUK
- Institute of Plant and Microbial Biology, Zurich‐Basel Plant Science CenterUniversity of ZurichZurichSwitzerland
| | - Yali Wei
- Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant SciencesChinese Academy of SciencesShanghaiChina
- University of Chinese Academy of SciencesBeijingChina
| | - Jian‐Min Zhou
- State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental BiologyChinese Academy of SciencesBeijingChina
| | - Frank L H Menke
- The Sainsbury LaboratoryUniversity of East Anglia, Norwich Research ParkNorwichUK
| | - Marco Trujillo
- Faculty of Biology, Institute of Biology IIAlbert‐Ludwigs‐University FreiburgFreiburgGermany
- Leibniz Institute for Plant BiochemistryHalle (Saale)Germany
| | - Cyril Zipfel
- The Sainsbury LaboratoryUniversity of East Anglia, Norwich Research ParkNorwichUK
- Institute of Plant and Microbial Biology, Zurich‐Basel Plant Science CenterUniversity of ZurichZurichSwitzerland
| | - Alberto P Macho
- Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant SciencesChinese Academy of SciencesShanghaiChina
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13
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Wang DR, Zhang XW, Xu RR, Wang GL, You CX, An JP. Apple U-box-type E3 ubiquitin ligase MdPUB23 reduces cold-stress tolerance by degrading the cold-stress regulatory protein MdICE1. HORTICULTURE RESEARCH 2022; 9:uhac171. [PMID: 36247364 PMCID: PMC9557189 DOI: 10.1093/hr/uhac171] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Accepted: 07/27/2022] [Indexed: 06/16/2023]
Abstract
Cold stress limits plant growth, geographical distribution, and crop yield. The MYC-type bHLH transcription factor ICE1 is recognized as the core positive regulator of the cold-stress response. However, how ICE1 protein levels are regulated remains to be further studied. In this study, we observed that a U-box-type E3 ubiquitin ligase, MdPUB23, positively regulated the cold-stress response in apple. The expression of MdPUB23 increased at both the transcriptional and post-translational levels in response to cold stress. Overexpression of MdPUB23 in transgenic apple enhanced sensitivity to cold stress. Further study showed that MdPUB23 directly interacted with MdICE1, promoting the ubiquitination-mediated degradation of the MdICE1 protein through the 26S-proteasome pathway and reducing the MdICE1-improved cold-stress tolerance in apple. Our results reveal that MdPUB23 regulates the cold-stress response by directly mediating the stability of the positive regulator MdICE1. The PUB23-ICE1 ubiquitination module may play a role in maintaining ICE1 protein homeostasis and preventing overreactions from causing damage to plants. The discovery of the ubiquitination regulatory pathway of ICE1 provides insights for the further exploration of plant cold-stress-response mechanisms.
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Affiliation(s)
| | | | - Rui-Rui Xu
- Key Laboratory of Biochemistry and Molecular Biology in Universities of Shandong, College of Biology and Oceanography, Weifang University, Weifang 261061, Shandong, China
| | - Gui-Luan Wang
- State Key Laboratory of Crop Biology, College of Horticulture Science and Engineering, Shandong Agricultural University, Tai-An, 271018, Shandong, China
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14
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Petutschnig E, Anders J, Stolze M, Meusel C, Hacke R, Much L, Schwier M, Gippert AL, Kroll S, Fasshauer P, Wiermer M, Lipka V. EXTRA LARGE G-PROTEIN2 mediates cell death and hyperimmunity in the chitin elicitor receptor kinase 1-4 mutant. PLANT PHYSIOLOGY 2022; 189:2413-2431. [PMID: 35522044 PMCID: PMC9342992 DOI: 10.1093/plphys/kiac214] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Accepted: 04/13/2022] [Indexed: 05/08/2023]
Abstract
Heterotrimeric G-proteins are signal transduction complexes that comprised three subunits, Gα, Gβ, and Gγ, and are involved in many aspects of plant life. The noncanonical Gα subunit EXTRA LARGE G-PROTEIN2 (XLG2) mediates pathogen-associated molecular pattern (PAMP)-induced reactive oxygen species (ROS) generation and immunity downstream of pattern recognition receptors. A mutant of the chitin receptor component CHITIN ELICITOR RECEPTOR KINASE1 (CERK1), cerk1-4, maintains normal chitin signaling capacity but shows excessive cell death upon infection with powdery mildew fungi. We identified XLG2 mutants as suppressors of the cerk1-4 phenotype. Mutations in XLG2 complex partners ARABIDOPSIS Gβ1 (AGB1) and Gγ1 (AGG1) have a partial cerk1-4 suppressor effect. Contrary to its role in PAMP-induced immunity, XLG2-mediated control of ROS production by RESPIRATORY BURST OXIDASE HOMOLOGUE D (RBOHD) is not critical for cerk1-4-associated cell death and hyperimmunity. The cerk1-4 phenotype is also independent of the co-receptor/adapter kinases BRI1-ASSOCIATED RECEPTOR KINASE 1 (BAK1) and SUPPRESSOR OF BIR1 1 (SOBIR1), but requires the E3 ubiquitin ligase PLANT U-BOX 2 (PUB2). XLG2 localizes to both the cell periphery and nucleus, and the cerk1-4 cell death phenotype is mediated by the cell periphery pool of XLG2. Integrity of the XLG2 N-terminal domain, but not its phosphorylation, is essential for correct XLG2 localization and formation of the cerk1-4 phenotype. Our results support a model in which XLG2 acts downstream of an unknown cell surface receptor that activates an NADPH oxidase-independent cell death pathway in Arabidopsis (Arabidopsis thaliana).
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Affiliation(s)
| | - Julia Anders
- Department of Plant Cell Biology, Albrecht-von-Haller-Institute for Plant Sciences, Georg-August-University Göttingen, Göttingen 37077, Germany
| | - Marnie Stolze
- Department of Plant Cell Biology, Albrecht-von-Haller-Institute for Plant Sciences, Georg-August-University Göttingen, Göttingen 37077, Germany
| | - Christopher Meusel
- Department of Plant Cell Biology, Albrecht-von-Haller-Institute for Plant Sciences, Georg-August-University Göttingen, Göttingen 37077, Germany
| | - Ronja Hacke
- Department of Plant Cell Biology, Albrecht-von-Haller-Institute for Plant Sciences, Georg-August-University Göttingen, Göttingen 37077, Germany
| | - Laura Much
- Department of Plant Cell Biology, Albrecht-von-Haller-Institute for Plant Sciences, Georg-August-University Göttingen, Göttingen 37077, Germany
| | - Melina Schwier
- Department of Plant Cell Biology, Albrecht-von-Haller-Institute for Plant Sciences, Georg-August-University Göttingen, Göttingen 37077, Germany
| | - Anna-Lena Gippert
- Department of Plant Cell Biology, Albrecht-von-Haller-Institute for Plant Sciences, Georg-August-University Göttingen, Göttingen 37077, Germany
| | - Samuel Kroll
- Department of Plant Cell Biology, Albrecht-von-Haller-Institute for Plant Sciences, Georg-August-University Göttingen, Göttingen 37077, Germany
| | - Patrick Fasshauer
- Department of Plant Cell Biology, Albrecht-von-Haller-Institute for Plant Sciences, Georg-August-University Göttingen, Göttingen 37077, Germany
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15
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Activation and turnover of the plant immune signaling kinase BIK1: a fine balance. Essays Biochem 2022; 66:207-218. [PMID: 35575190 DOI: 10.1042/ebc20210071] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Revised: 04/22/2022] [Accepted: 04/29/2022] [Indexed: 12/19/2022]
Abstract
Mechanisms to sense and respond to pathogens have evolved in all species. The plant immune pathway is initiated by the activation of transmembrane receptor kinases that trigger phosphorylation relays resulting in cellular reprogramming. BOTRYTIS-INDUCED KINASE 1 (BIK1) is a direct substrate of multiple immune receptors in Arabidopsis thaliana and is a central regulator of plant immunity. Here, we review how BIK1 activity and protein stability are regulated by a dynamic interplay between phosphorylation and ubiquitination.
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