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Zhang N, Dong X, Jain R, Ruan D, de Araujo Junior AT, Li Y, Lipzen A, Martin J, Barry K, Ronald PC. XA21-mediated resistance to Xanthomonas oryzae pv. oryzae is dose dependent. PeerJ 2024; 12:e17323. [PMID: 38726377 PMCID: PMC11080989 DOI: 10.7717/peerj.17323] [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: 09/28/2023] [Accepted: 04/10/2024] [Indexed: 05/12/2024] Open
Abstract
The rice receptor kinase XA21 confers broad-spectrum resistance to Xanthomonas oryzae pv. oryzae (Xoo), the causal agent of rice bacterial blight disease. To investigate the relationship between the expression level of XA21 and resulting resistance, we generated independent HA-XA21 transgenic rice lines accumulating the XA21 immune receptor fused with an HA epitope tag. Whole-genome sequence analysis identified the T-DNA insertion sites in sixteen independent T0 events. Through quantification of the HA-XA21 protein and assessment of the resistance to Xoo strain PXO99 in six independent transgenic lines, we observed that XA21-mediated resistance is dose dependent. In contrast, based on the four agronomic traits quantified in these experiments, yield is unlikely to be affected by the expression level of HA-XA21. These findings extend our knowledge of XA21-mediated defense and contribute to the growing number of well-defined genomic landing pads in the rice genome that can be targeted for gene insertion without compromising yield.
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Affiliation(s)
- Nan Zhang
- Key Laboratory of Seed Innovation, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
- Department of Plant Pathology and the Genome Center, University of California, Davis, CA, USA
| | - Xiaoou Dong
- Department of Plant Pathology and the Genome Center, University of California, Davis, CA, USA
- State Key Laboratory for Crop Genetics and Germplasm Enhancement and Utilization, Jiangsu Engineering Research Center for Plant Genome Editing, Nanjing Agricultural University, Nanjing, China
- Innovative Genomics Institute, University of California, Berkeley, CA, USA
- Feedstocks Division, The Joint Bioenergy Institute, Emeryville, CA, USA
| | - Rashmi Jain
- Department of Plant Pathology and the Genome Center, University of California, Davis, CA, USA
| | - Deling Ruan
- Department of Plant Pathology and the Genome Center, University of California, Davis, CA, USA
- Feedstocks Division, The Joint Bioenergy Institute, Emeryville, CA, USA
| | | | - Yan Li
- Department of Plant Pathology and the Genome Center, University of California, Davis, CA, USA
- Rice Research Institute and Key Lab for Major Crop Diseases, Sichuan Agricultural University, Chengdu, China
| | - Anna Lipzen
- DOE Joint Genome Institute, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Joel Martin
- DOE Joint Genome Institute, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Kerrie Barry
- DOE Joint Genome Institute, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Pamela C. Ronald
- Department of Plant Pathology and the Genome Center, University of California, Davis, CA, USA
- Innovative Genomics Institute, University of California, Berkeley, CA, USA
- Feedstocks Division, The Joint Bioenergy Institute, Emeryville, CA, USA
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2
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Shepherd S, Yuen ELH, Carella P, Bozkurt TO. The wheels of destruction: Plant NLR immune receptors are mobile and structurally dynamic disease resistance proteins. CURRENT OPINION IN PLANT BIOLOGY 2023; 74:102372. [PMID: 37172365 DOI: 10.1016/j.pbi.2023.102372] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2022] [Revised: 02/23/2023] [Accepted: 04/04/2023] [Indexed: 05/14/2023]
Abstract
Nucleotide-binding leucine-rich repeat (NLR) proteins are intracellular immune receptors that restrict plant invasion by pathogens. Most NLRs operate in intricate networks to detect pathogen effectors in a robust and efficient manner. NLRs are not static sensors; rather, they exhibit remarkable mobility and structural plasticity during the innate immune response. Inactive NLRs localize to diverse subcellular compartments where they are poised to sense pathogen effectors. During pathogen attack, some NLRs relocate toward the plant-pathogen interface, possibly to ensure their timely activation. Activated NLRs reorganize into wheel-shaped oligomers, some of which then form plasma membrane pores that promote calcium influx and programmed cell death. The emerging paradigm is that this variable and dynamic nature underpins effective NLR-mediated immunity.
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Affiliation(s)
- Samuel Shepherd
- Department of Life Sciences, Imperial College, London, United Kingdom
| | | | | | - Tolga O Bozkurt
- Department of Life Sciences, Imperial College, London, United Kingdom.
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3
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Sun Y, Ma S, Liu X, Wang GF. The maize ZmVPS23-like protein relocates the nucleotide-binding leucine-rich repeat protein Rp1-D21 to endosomes and suppresses the defense response. THE PLANT CELL 2023; 35:2369-2390. [PMID: 36869653 PMCID: PMC10226561 DOI: 10.1093/plcell/koad061] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Revised: 02/09/2023] [Accepted: 02/28/2023] [Indexed: 05/30/2023]
Abstract
Plants often utilize nucleotide-binding leucine-rich repeat (NLR) proteins to perceive pathogen infections and trigger a hypersensitive response (HR). The endosomal sorting complex required for transport (ESCRT) machinery is a conserved multisubunit complex that is essential for the biogenesis of multivesicular bodies and cargo protein sorting. VPS23 is a key component of ESCRT-I and plays important roles in plant development and abiotic stresses. ZmVPS23L, a homolog of VPS23-like in maize (Zea mays), was previously identified as a candidate gene in modulating HR mediated by the autoactive NLR protein Rp1-D21 in different maize populations. Here, we demonstrate that ZmVPS23L suppresses Rp1-D21-mediated HR in maize and Nicotiana benthamiana. Variation in the suppressive effect of HR by different ZmVPS23L alleles was correlated with variation in their expression levels. ZmVPS23 also suppressed Rp1-D21-mediated HR. ZmVPS23L and ZmVPS23 predominantly localized to endosomes, and they physically interacted with the coiled-coil domain of Rp1-D21 and mediated the relocation of Rp1-D21 from the nucleo-cytoplasm to endosomes. In summary, we demonstrate that ZmVPS23L and ZmVPS23 are negative regulators of Rp1-D21-mediated HR, likely by sequestrating Rp1-D21 in endosomes via physical interaction. Our findings reveal the role of ESCRT components in controlling plant NLR-mediated defense responses.
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Affiliation(s)
- Yang Sun
- The Key Laboratory of Plant Development and Environmental Adaptation Biology, Ministry of Education, School of Life Sciences, Shandong University, Qingdao, Shandong 266237, China
| | - Shijun Ma
- The Key Laboratory of Plant Development and Environmental Adaptation Biology, Ministry of Education, School of Life Sciences, Shandong University, Qingdao, Shandong 266237, China
| | - Xiangguo Liu
- Institute of Agricultural Biotechnology, Jilin Academy of Agricultural Sciences, Changchun 130033, Jilin, China
| | - Guan-Feng Wang
- The Key Laboratory of Plant Development and Environmental Adaptation Biology, Ministry of Education, School of Life Sciences, Shandong University, Qingdao, Shandong 266237, China
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4
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Tehrani N, Mitra RM. Plant pathogens and symbionts target the plant nucleus. Curr Opin Microbiol 2023; 72:102284. [PMID: 36868049 DOI: 10.1016/j.mib.2023.102284] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Revised: 01/20/2023] [Accepted: 01/24/2023] [Indexed: 03/05/2023]
Abstract
In plant-microbe interactions, symbionts and pathogens live within plants and attempt to avoid triggering plant defense responses. In order to do so, these microbes have evolved multiple mechanisms that target components of the plant cell nucleus. Rhizobia-induced symbiotic signaling requires the function of specific legume nucleoporins within the nuclear pore complex. Symbiont and pathogen effectors harbor nuclear localization sequences that facilitate movement across nuclear pores, allowing these proteins to target transcription factors that function in defense. Oomycete pathogens introduce proteins that interact with plant pre-mRNA splicing components in order to alter host splicing of defense-related transcripts. Together, these functions indicate that the nucleus is an active site of symbiotic and pathogenic functioning in plant-microbe interactions.
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5
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Bernoux M, Chen J, Zhang X, Newell K, Hu J, Deslandes L, Dodds P. Subcellular localization requirements and specificities for plant immune receptor Toll-interleukin-1 receptor signaling. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2023. [PMID: 36932864 DOI: 10.1111/tpj.16195] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2022] [Revised: 02/24/2023] [Accepted: 03/01/2023] [Indexed: 06/02/2023]
Abstract
Recent work shed light on how plant intracellular immune receptors of the nucleotide-binding leucine-rich repeat (NLR) family are activated upon pathogen effector recognition to trigger immune responses. Activation of Toll-interleukin-1 receptor (TIR) domain-containing NLRs (TNLs) induces receptor oligomerization and close proximity of the TIR domain, which is required for TIR enzymatic activity. TIR-catalyzed small signaling molecules bind to EDS1 family heterodimers and subsequently activate downstream helper NLRs, which function as Ca2+ permeable channel to activate immune responses eventually leading to cell death. Subcellular localization requirements of TNLs and signaling partners are not well understood, although they are required to understand fully the mechanisms underlying NLR early signaling. TNLs show diverse subcellular localization while EDS1 shows nucleocytosolic localization. Here, we studied the impact of TIR and EDS1 mislocalization on the signaling activation of different TNLs. In Nicotiana benthamiana, our results suggest that close proximity of TIR domains isolated from flax L6 and Arabidopsis RPS4 and SNC1 TNLs drives signaling activation from different cell compartments. Nevertheless, both Golgi-membrane anchored L6 and nucleocytosolic RPS4 have the same requirements for EDS1 subcellular localization in Arabidopsis thaliana. By using mislocalized variants of EDS1, we found that autoimmune L6 and RPS4 TIR domain can induce seedling cell death when EDS1 is present in the cytosol. However, when EDS1 is restricted to the nucleus, both induce a stunting phenotype but no cell death. Our data point out the importance of thoroughly investigating the dynamics of TNLs and signaling partners subcellular localization to understand TNL signaling fully.
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Affiliation(s)
- Maud Bernoux
- Laboratoire des Interactions Plantes-Microbes-Environnement (LIPME), UMR 2594/441 CNRS, INRAE, 31326, Castanet-Tolosan, France
| | - Jian Chen
- Agriculture and Food, Commonwealth Scientific and Industrial Research Organization, Canberra, ACT 2601, Australia
| | - Xiaoxiao Zhang
- Research School of Biology, Australian National University, Canberra, ACT 2601, Australia
| | - Kim Newell
- Agriculture and Food, Commonwealth Scientific and Industrial Research Organization, Canberra, ACT 2601, Australia
| | - Jian Hu
- Department of Biochemistry and Molecular Biology, College of Biological Sciences, China Agricultural University, Beijing, 100094, People's Republic of China
| | - Laurent Deslandes
- Laboratoire des Interactions Plantes-Microbes-Environnement (LIPME), UMR 2594/441 CNRS, INRAE, 31326, Castanet-Tolosan, France
| | - Peter Dodds
- Agriculture and Food, Commonwealth Scientific and Industrial Research Organization, Canberra, ACT 2601, Australia
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6
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Tran S, Ison M, Ferreira Dias NC, Ortega MA, Chen YFS, Peper A, Hu L, Xu D, Mozaffari K, Severns PM, Yao Y, Tsai CJ, Teixeira PJPL, Yang L. Endogenous salicylic acid suppresses de novo root regeneration from leaf explants. PLoS Genet 2023; 19:e1010636. [PMID: 36857386 PMCID: PMC10010561 DOI: 10.1371/journal.pgen.1010636] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Revised: 03/13/2023] [Accepted: 01/25/2023] [Indexed: 03/02/2023] Open
Abstract
Plants can regenerate new organs from damaged or detached tissues. In the process of de novo root regeneration (DNRR), adventitious roots are frequently formed from the wound site on a detached leaf. Salicylic acid (SA) is a key phytohormone regulating plant defenses and stress responses. The role of SA and its acting mechanisms during de novo organogenesis is still unclear. Here, we found that endogenous SA inhibited the adventitious root formation after cutting. Free SA rapidly accumulated at the wound site, which was accompanied by an activation of SA response. SA receptors NPR3 and NPR4, but not NPR1, were required for DNRR. Wounding-elevated SA compromised the expression of AUX1, and subsequent transport of auxin to the wound site. A mutation in AUX1 abolished the enhanced DNRR in low SA mutants. Our work elucidates a role of SA in regulating DNRR and suggests a potential link between biotic stress and tissue regeneration.
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Affiliation(s)
- Sorrel Tran
- Department of Plant Pathology, College of Agricultural & Environmental Sciences, University of Georgia, Athens, Georgia, United States of America
| | - Madalene Ison
- Department of Plant Pathology, College of Agricultural & Environmental Sciences, University of Georgia, Athens, Georgia, United States of America
| | | | - Maria Andrea Ortega
- Warnell School of Forestry and Natural Resources, University of Georgia, Athens, Georgia, United States of America
- Department of Genetics, Franklin College of Arts and Sciences, University of Georgia, Athens, Georgia, United States of America
- Department of Plant Biology, Franklin College of Arts and Sciences, University of Georgia, Athens, Georgia, United States of America
| | - Yun-Fan Stephanie Chen
- Department of Plant Pathology, College of Agricultural & Environmental Sciences, University of Georgia, Athens, Georgia, United States of America
| | - Alan Peper
- Department of Plant Pathology, College of Agricultural & Environmental Sciences, University of Georgia, Athens, Georgia, United States of America
| | - Lanxi Hu
- Department of Plant Pathology, College of Agricultural & Environmental Sciences, University of Georgia, Athens, Georgia, United States of America
| | - Dawei Xu
- Department of Plant Pathology, College of Agricultural & Environmental Sciences, University of Georgia, Athens, Georgia, United States of America
| | - Khadijeh Mozaffari
- Warnell School of Forestry and Natural Resources, University of Georgia, Athens, Georgia, United States of America
| | - Paul M. Severns
- Department of Plant Pathology, College of Agricultural & Environmental Sciences, University of Georgia, Athens, Georgia, United States of America
| | - Yao Yao
- Department of Animal and Diary Sciences, College of Agricultural & Environmental Sciences, University of Georgia, Georgia, United States of America
| | - Chung-Jui Tsai
- Warnell School of Forestry and Natural Resources, University of Georgia, Athens, Georgia, United States of America
- Department of Genetics, Franklin College of Arts and Sciences, University of Georgia, Athens, Georgia, United States of America
- Department of Plant Biology, Franklin College of Arts and Sciences, University of Georgia, Athens, Georgia, United States of America
| | - Paulo José Pereira Lima Teixeira
- Department of Biology, "Luiz de Queiroz" College of Agriculture, University of São Paulo, Sao Paulo, Brazil
- * E-mail: (PJPLT); (LY)
| | - Li Yang
- Department of Plant Pathology, College of Agricultural & Environmental Sciences, University of Georgia, Athens, Georgia, United States of America
- * E-mail: (PJPLT); (LY)
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7
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Wang Z, Yang L, Hua J. The intracellular immune receptor like gene SNC1 is an enhancer of effector-triggered immunity in Arabidopsis. PLANT PHYSIOLOGY 2023; 191:874-884. [PMID: 36449532 PMCID: PMC9922396 DOI: 10.1093/plphys/kiac543] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Accepted: 11/29/2022] [Indexed: 06/17/2023]
Abstract
Plants contain many nucleotide-binding leucine-rich repeat (NLR) proteins that are postulated to function as intracellular immune receptors but do not yet have an identified function during plant-pathogen interactions. SUPPRESSOR OF NPR1-1, CONSTITUTIVE 1 (SNC1) is one such NLR protein of the Toll-interleukin 1 receptor (TIR) type, despite its well-characterized gain-of-function activity and its involvement in autoimmunity in Arabidopsis (Arabidopsis thaliana). Here, we investigated the role of SNC1 in natural plant-pathogen interactions and genetically tested the importance of the enzymatic activities of its TIR domain for its function. The SNC1 loss-of-function mutants were more susceptible to avirulent bacterial pathogen strains of Pseudomonas syringae containing specific effectors, especially under constant light growth condition. The mutants also had reduced defense gene expression induction and hypersensitive responses upon infection by avirulent pathogens under constant light growth condition. In addition, genetic and biochemical studies supported that the TIR enzymatic activity of SNC1 is required for its gain-of-function activity. In sum, our study uncovers the role of SNC1 as an amplifier of plant defense responses during natural plant-pathogen interactions and indicates its use of enzymatic activity and intermolecular interactions for triggering autoimmune responses.
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Affiliation(s)
- Zhixue Wang
- Plant Biology section, School of Integrative Plant Science, Cornell University, Ithaca, NY 14853, USA
| | - Leiyun Yang
- Plant Biology section, School of Integrative Plant Science, Cornell University, Ithaca, NY 14853, USA
| | - Jian Hua
- Plant Biology section, School of Integrative Plant Science, Cornell University, Ithaca, NY 14853, USA
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8
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Tian L, Lu J, Li X. Differential requirement of TIR enzymatic activities in TIR-type immune receptor SNC1-mediated immunity. PLANT PHYSIOLOGY 2022; 190:2094-2098. [PMID: 36149306 PMCID: PMC9706416 DOI: 10.1093/plphys/kiac452] [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: 07/12/2022] [Accepted: 08/24/2022] [Indexed: 05/06/2023]
Abstract
Arabidopsis thaliana TIR-type immune receptor SNC1 (Suppressor of npr1-1, constitutive 1) requires NADase, but not the 2′,3′-cAMP/cGMP synthetase activity to trigger in planta immune responses.
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Affiliation(s)
- Lei Tian
- Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
- Department of Botany, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - Junxing Lu
- College of Life Science, Chongqing Normal University, Chongqing, 401331, China
| | - Xin Li
- Author for correspondence:
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9
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Lüdke D, Yan Q, Rohmann PFW, Wiermer M. NLR we there yet? Nucleocytoplasmic coordination of NLR-mediated immunity. THE NEW PHYTOLOGIST 2022; 236:24-42. [PMID: 35794845 DOI: 10.1111/nph.18359] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Accepted: 06/07/2022] [Indexed: 06/15/2023]
Abstract
Plant intracellular nucleotide-binding leucine-rich repeat immune receptors (NLRs) perceive the activity of pathogen-secreted effector molecules that, when undetected, promote colonisation of hosts. Signalling from activated NLRs converges with and potentiates downstream responses from activated pattern recognition receptors (PRRs) that sense microbial signatures at the cell surface. Efficient signalling of both receptor branches relies on the host cell nucleus as an integration point for transcriptional reprogramming, and on the macromolecular transport processes that mediate the communication between cytoplasm and nucleoplasm. Studies on nuclear pore complexes (NPCs), the nucleoporin proteins (NUPs) that compose NPCs, and nuclear transport machinery constituents that control nucleocytoplasmic transport, have revealed that they play important roles in regulating plant immune responses. Here, we discuss the contributions of nucleoporins and nuclear transport receptor (NTR)-mediated signal transduction in plant immunity with an emphasis on NLR immune signalling across the nuclear compartment boundary and within the nucleus. We also highlight and discuss cytoplasmic and nuclear functions of NLRs and their signalling partners and further consider the potential implications of NLR activation and resistosome formation in both cellular compartments for mediating plant pathogen resistance and programmed host cell death.
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Affiliation(s)
- Daniel Lüdke
- Molecular Biology of Plant-Microbe Interactions Research Group, Albrecht-von-Haller-Institute for Plant Sciences, University of Goettingen, Julia-Lermontowa-Weg 3, 37077, Goettingen, Germany
| | - Qiqi Yan
- Molecular Biology of Plant-Microbe Interactions Research Group, Albrecht-von-Haller-Institute for Plant Sciences, University of Goettingen, Julia-Lermontowa-Weg 3, 37077, Goettingen, Germany
| | - Philipp F W Rohmann
- Molecular Biology of Plant-Microbe Interactions Research Group, Albrecht-von-Haller-Institute for Plant Sciences, University of Goettingen, Julia-Lermontowa-Weg 3, 37077, Goettingen, Germany
| | - Marcel Wiermer
- Molecular Biology of Plant-Microbe Interactions Research Group, Albrecht-von-Haller-Institute for Plant Sciences, University of Goettingen, Julia-Lermontowa-Weg 3, 37077, Goettingen, Germany
- Biochemistry of Plant-Microbe Interactions, Dahlem Centre of Plant Sciences, Institute of Biology, Freie Universität Berlin, Königin-Luise-Str. 12-16, 14195, Berlin, Germany
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10
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Yan T, Zhou Z, Wang R, Bao D, Li S, Li A, Yu R, Wuriyanghan H. A cluster of atypical resistance genes in soybean confers broad-spectrum antiviral activity. PLANT PHYSIOLOGY 2022; 188:1277-1293. [PMID: 34730802 PMCID: PMC8825445 DOI: 10.1093/plphys/kiab507] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Accepted: 10/02/2021] [Indexed: 06/12/2023]
Abstract
Soybean mosaic virus (SMV) is a severe soybean (Glycine max) pathogen. Here we characterize a soybean SMV resistance cluster (SRC) that comprises five resistance (R) genes. SRC1 encodes a Toll/interleukin-1 receptor and nucleotide-binding site (TIR-NBS [TN]) protein, SRC4 and SRC6 encode TIR proteins with a short EF-hand domain, while SRC7 and SRC8 encode TNX proteins with a noncanonical basic secretory protein (BSP) domain at their C-termini. We mainly studied SRC7, which contains a noncanonical BSP domain and gave full resistance to SMV. SRC7 possessed broad-spectrum antiviral activity toward several plant viruses including SMV, plum pox virus, potato virus Y, and tobacco mosaic virus. The TIR domain alone was both necessary and sufficient for SRC7 immune signaling, while the NBS domain enhanced its activity. Nuclear oligomerization via the interactions of both TIR and NBS domains was essential for SRC7 function. SRC7 expression was transcriptionally inducible by SMV infection and salicylic acid (SA) treatment, and SA was required for SRC7 triggered virus resistance. SRC7 expression was posttranscriptionally regulated by miR1510a and miR2109, and the SRC7-miR1510a/miR2109 regulatory network appeared to contribute to SMV-soybean interactions in both resistant and susceptible soybean cultivars. In summary, we report a soybean R gene cluster centered by SRC7 that is regulated at both transcriptional and posttranscriptional levels, possesses a yet uncharacterized BSP domain, and has broad-spectrum antiviral activities. The SRC cluster is special as it harbors several functional R genes encoding atypical TIR-NBS-LRR (TNL) type R proteins, highlighting its importance in SMV-soybean interaction and plant immunity.
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Affiliation(s)
- Ting Yan
- Key Laboratory of Forage and Endemic Crop Biotechnology, Ministry of Education, School of Life Sciences, Inner Mongolia University, Hohhot, 010070, China
| | - Zikai Zhou
- Key Laboratory of Forage and Endemic Crop Biotechnology, Ministry of Education, School of Life Sciences, Inner Mongolia University, Hohhot, 010070, China
| | - Ru Wang
- Key Laboratory of Forage and Endemic Crop Biotechnology, Ministry of Education, School of Life Sciences, Inner Mongolia University, Hohhot, 010070, China
| | - Duran Bao
- Key Laboratory of Forage and Endemic Crop Biotechnology, Ministry of Education, School of Life Sciences, Inner Mongolia University, Hohhot, 010070, China
| | - Shanshan Li
- Key Laboratory of Forage and Endemic Crop Biotechnology, Ministry of Education, School of Life Sciences, Inner Mongolia University, Hohhot, 010070, China
| | - Aoga Li
- Key Laboratory of Forage and Endemic Crop Biotechnology, Ministry of Education, School of Life Sciences, Inner Mongolia University, Hohhot, 010070, China
| | - Ruonan Yu
- Key Laboratory of Forage and Endemic Crop Biotechnology, Ministry of Education, School of Life Sciences, Inner Mongolia University, Hohhot, 010070, China
| | - Hada Wuriyanghan
- Key Laboratory of Forage and Endemic Crop Biotechnology, Ministry of Education, School of Life Sciences, Inner Mongolia University, Hohhot, 010070, China
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11
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Fang Y, Gu Y. Regulation of Plant Immunity by Nuclear Membrane-Associated Mechanisms. Front Immunol 2021; 12:771065. [PMID: 34938291 PMCID: PMC8685260 DOI: 10.3389/fimmu.2021.771065] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2021] [Accepted: 11/18/2021] [Indexed: 12/25/2022] Open
Abstract
Unlike animals, plants do not have specialized immune cells and lack an adaptive immune system. Instead, plant cells rely on their unique innate immune system to defend against pathogens and coordinate beneficial interactions with commensal and symbiotic microbes. One of the major convergent points for plant immune signaling is the nucleus, where transcriptome reprogramming is initiated to orchestrate defense responses. Mechanisms that regulate selective transport of nuclear signaling cargo and chromatin activity at the nuclear boundary play a pivotal role in immune activation. This review summarizes the current knowledge of how nuclear membrane-associated core protein and protein complexes, including the nuclear pore complex, nuclear transport receptors, and the nucleoskeleton participate in plant innate immune activation and pathogen resistance. We also discuss the role of their functional counterparts in regulating innate immunity in animals and highlight potential common mechanisms that contribute to nuclear membrane-centered immune regulation in higher eukaryotes.
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Affiliation(s)
- Yiling Fang
- Department of Plant and Microbial Biology, University of California, Berkeley, CA, United States.,Innovative Genomics Institute, University of California, Berkeley, CA, United States
| | - Yangnan Gu
- Department of Plant and Microbial Biology, University of California, Berkeley, CA, United States.,Innovative Genomics Institute, University of California, Berkeley, CA, United States
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12
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Zhao J, Song J. NLR immune receptor RB is differentially targeted by two homologous but functionally distinct effector proteins. PLANT COMMUNICATIONS 2021; 2:100236. [PMID: 34778749 PMCID: PMC8577132 DOI: 10.1016/j.xplc.2021.100236] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/20/2021] [Revised: 08/05/2021] [Accepted: 08/20/2021] [Indexed: 06/13/2023]
Abstract
Plant nucleotide-binding leucine-rich repeat (NLR) receptors mediate immune responses by directly or indirectly sensing pathogen-derived effectors. Despite significant advances in the understanding of NLR-mediated immunity, the mechanisms by which pathogens evolve to suppress NLR activation triggered by cognate effectors and gain virulence remain largely unknown. The agronomically important immune receptor RB recognizes the ubiquitous and highly conserved IPI-O RXLR family members (e.g., IPI-O1) from Phytophthora infestans, and this process is suppressed by the rarely present and homologous effector IPI-O4. Here, we report that self-association of RB via the coiled-coil (CC) domain is required for RB activation and is differentially affected by avirulence and virulence effectors. IPI-O1 moderately reduces the self-association of RB CC, potentially leading to changes in the conformation and equilibrium of RB, whereas IPI-O4 dramatically impairs CC self-association to prevent RB activation. We also found that IPI-O1 associates with itself, whereas IPI-O4 does not. Notably, IPI-O4 interacts with IPI-O1 and disrupts its self-association, therefore probably blocking its avirulence function. Furthermore, IPI-O4 enhances the interaction between RB CC and IPI-O1, possibly sequestering RB and IPI-O1 and subsequently blocking their interactions with signaling components. Taken together, these findings considerably extend our understanding of the underlying mechanisms by which emerging virulent pathogens suppress the NLR-mediated recognition of cognate effectors.
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Affiliation(s)
- Jinping Zhao
- Texas A&M AgriLife Research Center at Dallas, Dallas, TX 75252, USA
| | - Junqi Song
- Texas A&M AgriLife Research Center at Dallas, Dallas, TX 75252, USA
- Department of Plant Pathology and Microbiology, Texas A&M University, College Station, TX 77843, USA
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13
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Jia M, Shen X, Tang Y, Shi X, Gu Y. A karyopherin constrains nuclear activity of the NLR protein SNC1 and is essential to prevent autoimmunity in Arabidopsis. MOLECULAR PLANT 2021; 14:1733-1744. [PMID: 34153500 DOI: 10.1016/j.molp.2021.06.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Revised: 06/15/2021] [Accepted: 06/17/2021] [Indexed: 06/13/2023]
Abstract
The nucleotide-binding and leucine-rich repeat (NLR) proteins comprise a major class of intracellular immune receptors that are capable of detecting pathogen-derived molecules and activating immunity and cell death in plants. The activity of some NLRs, particularly the Toll-like/interleukin-1 receptor (TIR) type, is highly correlated with their nucleocytoplasmic distribution. However, whether and how the nucleocytoplasmic homeostasis of NLRs is coordinated through a bidirectional nuclear shuttling mechanism remains unclear. Here, we identified a nuclear transport receptor, KA120, which is capable of affecting the nucleocytoplasmic distribution of an NLR protein and is essential in preventing its autoactivation. We showed that the ka120 mutant displays an autoimmune phenotype and NLR-induced transcriptome features. Through a targeted genetic screen using an artificial NLR microRNA library, we identified the TIR-NLR gene SNC1 as a genetic interactor of KA120. Loss-of-function snc1 mutations as well as compromising SNC1 protein activities all substantially suppressed ka120-induced autoimmune activation, and the enhanced SNC1 activity upon loss of KA120 functionappeared to occur at the protein level. Overexpression of KA120 efficiently repressed SNC1 activity and led to a nearly complete suppression of the autoimmune phenotype caused by the gain-of-function snc1-1 mutation or SNC1 overexpression in transgenic plants. Further florescence imaging analysis indicated that SNC1 undergoes altered nucleocytoplasmic distribution with significantly reduced nuclear signal when KA120 is constitutively expressed, supporting a role of KA120 in coordinating SNC1 nuclear abundance and activity. Consistently, compromising the SNC1 nuclear level by disrupting the nuclear pore complex could also partially rescue ka120-induced autoimmunity. Collectively, our study demonstrates that KA120 is essential to avoid autoimmune activation in the absence of pathogens and is required to constrain the nuclear activity of SNC1, possibly through coordinating SNC1 nucleocytoplasmic homeostasis as a potential mechanism.
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Affiliation(s)
- Min Jia
- Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720, USA; Innovative Genomics Institute, University of California, Berkeley, CA 94720, USA
| | - Xueqi Shen
- Tsinghua-Peking Joint Center for Life Sciences, Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Yu Tang
- Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720, USA; Innovative Genomics Institute, University of California, Berkeley, CA 94720, USA
| | - Xuetao Shi
- Tsinghua-Peking Joint Center for Life Sciences, Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Yangnan Gu
- Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720, USA; Innovative Genomics Institute, University of California, Berkeley, CA 94720, USA.
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14
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Richard MMS, Knip M, Schachtschabel J, Beijaert MS, Takken FLW. Perturbation of nuclear-cytosolic shuttling of Rx1 compromises extreme resistance and translational arrest of potato virus X transcripts. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2021; 106:468-479. [PMID: 33524169 PMCID: PMC8252585 DOI: 10.1111/tpj.15179] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 01/24/2021] [Accepted: 01/26/2021] [Indexed: 06/01/2023]
Abstract
Many plant intracellular immune receptors mount a hypersensitive response (HR) upon pathogen perception. The concomitant localized cell death is proposed to trap pathogens, such as viruses, inside infected cells, thereby preventing their spread. Notably, extreme resistance (ER) conferred by the potato immune receptor Rx1 to potato virus X (PVX) does not involve the death of infected cells. It is unknown what defines ER and how it differs from HR-based resistance. Interestingly, Rx1 can trigger an HR, but only upon artificial (over)expression of PVX or its avirulence coat protein (CP). Rx1 has a nucleocytoplasmic distribution and both pools are required for HR upon transient expression of a PVX-GFP amplicon. It is unknown whether mislocalized Rx1 variants can induce ER upon natural PVX infection. Here, we generated transgenic Nicotiana benthamiana producing nuclear- or cytosol-restricted Rx1 variants. We found that these variants can still mount an HR. However, nuclear- or cytosol-restricted Rx1 variants can no longer trigger ER or restricts viral infection. Interestingly, unlike the mislocalized Rx1 variants, wild-type Rx1 was found to compromise CP protein accumulation. We show that the lack of CP accumulation does not result from its degradation but is likely to be linked with translational arrest of its mRNA. Together, our findings suggest that translational arrest of viral genes is a major component of ER and, unlike the HR, is required for resistance to PVX.
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Affiliation(s)
- Manon M. S. Richard
- Molecular Plant PathologySwammerdam Institute for Life Sciences (SILS)University of AmsterdamAmsterdamthe Netherlands
| | - Marijn Knip
- Molecular Plant PathologySwammerdam Institute for Life Sciences (SILS)University of AmsterdamAmsterdamthe Netherlands
| | - Joëlle Schachtschabel
- Molecular Plant PathologySwammerdam Institute for Life Sciences (SILS)University of AmsterdamAmsterdamthe Netherlands
| | - Machiel S. Beijaert
- Molecular Plant PathologySwammerdam Institute for Life Sciences (SILS)University of AmsterdamAmsterdamthe Netherlands
| | - Frank L. W. Takken
- Molecular Plant PathologySwammerdam Institute for Life Sciences (SILS)University of AmsterdamAmsterdamthe Netherlands
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15
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Ao K, Tong M, Li L, Lüdke D, Lipka V, Chen S, Wiermer M, Li X. SCF SNIPER7 controls protein turnover of unfoldase CDC48A to promote plant immunity. THE NEW PHYTOLOGIST 2021; 229:2795-2811. [PMID: 33156518 DOI: 10.1111/nph.17071] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Accepted: 11/01/2020] [Indexed: 06/11/2023]
Abstract
The unfoldase CDC48 (Cell Division Cycle 48) is highly conserved in eukaryotes, serving as an AAA + ATPase to extract ubiquitinated proteins from large protein complexes and membranes. Although its biochemical properties have been studied extensively in yeast and animal systems, the biological roles and regulations of the plant CDC48s have been explored only recently. Here we describe the identification of a novel E3 ligase from the SNIPER (snc1-influencing plant E3 ligase reverse genetic) screen, which contributes to plant defense regulation by targeting CDC48A for degradation. SNIPER7 encodes an F-box protein and its overexpression leads to autoimmunity. We identified CDC48s as interactors of SNIPER7 through immunoprecipitation followed by mass spectrometry proteomic analysis. SNIPER7 overexpression lines phenocopy the autoimmune mutant Atcdc48a-4. Furthermore, CDC48A protein levels are reduced or stabilized when SNIPER7 is overexpressed or inhibited, respectively, suggesting that CDC48A is the ubiquitination substrate of SCFSNIPER7 . Taken together, this study reveals a new mechanism where a SCFSNIPER7 complex regulates CDC48 unfoldase levels and modulates immune output.
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Affiliation(s)
- Kevin Ao
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
- Department of Botany, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
| | - Meixuezi Tong
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
- Department of Botany, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
| | - Lin Li
- National Institute of Biological Sciences, Beijing, 102206, China
| | - Daniel Lüdke
- Molecular Biology of Plant-Microbe Interactions Research Group, Albrecht-von-Haller-Institute for Plant Sciences, University of Goettingen, Goettingen, D-37077, Germany
| | - Volker Lipka
- Department of Plant Cell Biology, Albrecht-von-Haller-Institute for Plant Sciences, University of Goettingen, Goettingen, D-37077, Germany
- Central Microscopy Facility of the Faculty of Biology and Psychology, University of Goettingen, Goettingen, D-37077, Germany
| | - She Chen
- National Institute of Biological Sciences, Beijing, 102206, China
| | - Marcel Wiermer
- Molecular Biology of Plant-Microbe Interactions Research Group, Albrecht-von-Haller-Institute for Plant Sciences, University of Goettingen, Goettingen, D-37077, Germany
| | - Xin Li
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
- Department of Botany, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
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16
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Huang J, Wu X, Sun K, Gao Z. Structure and function analysis of a CC-NBS-LRR protein AT1G12290. Biochem Biophys Res Commun 2021; 534:206-211. [PMID: 33272575 DOI: 10.1016/j.bbrc.2020.11.111] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Accepted: 11/27/2020] [Indexed: 01/10/2023]
Abstract
Nucleotide-binding site (NBS) and leucine-rich repeat (LRR) receptors (NLRs) play important roles in plant immunity. The genome of Arabidopsis thaliana contains about 150 genes encoding NLR proteins, but few of them have been studied. We transiently expressed a series of NBS-LRR proteins in the leaves of Nicotiana benthamiana, and found that the CC-NBS-LRR protein (AT1G12290) was able to trigger cell death, a characterized function for the activation of an NLR protein. We observed that the YFP-tagged AT1G12290 was localized on the plasma membrane (PM), and the predicted myristoylation site Gly2 is required for the localization and function of the protein. Further structure dissection revealed that the CC domain was enough to activate cell death, and the N-terminal 1-100 amino acid fragment was the minimal region to induce cell death and self-association. Our research provides important clues to elucidate the activation mechanism of AT1G12290.
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Affiliation(s)
- Jianzhong Huang
- State Key Laboratory of Hybrid Rice, Key Laboratory for Research and Utilization of Heterosis in Indica Rice of Ministry of Agriculture, College of Life Sciences, Wuhan University, Wuhan, 430072, China
| | - Xiaoqiu Wu
- State Key Laboratory of Hybrid Rice, Key Laboratory for Research and Utilization of Heterosis in Indica Rice of Ministry of Agriculture, College of Life Sciences, Wuhan University, Wuhan, 430072, China
| | - Kaiting Sun
- State Key Laboratory of Hybrid Rice, Key Laboratory for Research and Utilization of Heterosis in Indica Rice of Ministry of Agriculture, College of Life Sciences, Wuhan University, Wuhan, 430072, China
| | - Zhiyong Gao
- State Key Laboratory of Hybrid Rice, Key Laboratory for Research and Utilization of Heterosis in Indica Rice of Ministry of Agriculture, College of Life Sciences, Wuhan University, Wuhan, 430072, China.
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17
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SUSA2 is an F-box protein required for autoimmunity mediated by paired NLRs SOC3-CHS1 and SOC3-TN2. Nat Commun 2020; 11:5190. [PMID: 33060601 PMCID: PMC7562919 DOI: 10.1038/s41467-020-19033-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Accepted: 09/24/2020] [Indexed: 12/20/2022] Open
Abstract
Both higher plants and mammals rely on nucleotide-binding leucine-rich repeat (NLR) immune receptors to detect pathogens and initiate immunity. Upon effector recognition, plant NLRs oligomerize for defense activation, the mechanism of which is poorly understood. We previously showed that disruption of the E3 ligase, Senescence-Associated E3 Ubiquitin Ligase 1 (SAUL1) leads to the activation of the NLR SOC3. Here, we report the identification of suppressor of saul1 2 (susa2) and susa3 from the saul1-1 suppressor screen. Pairwise interaction analysis suggests that both SUSA proteins interact with components of an SCFSUSA2 E3 ligase complex as well as CHS1 or TN2, truncated NLRs that pair with SOC3. susa2-2 only suppresses the autoimmunity mediated by either CHS1 or TN2, suggesting its specific involvement in SOC3-mediated immunity. In summary, our study indicates links between plant NLRs and an SCF complex that may enable ubiquitination and degradation of unknown downstream components to activate defense.
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18
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Wu Z, Tong M, Tian L, Zhu C, Liu X, Zhang Y, Li X. Plant E3 ligases SNIPER1 and SNIPER2 broadly regulate the homeostasis of sensor NLR immune receptors. EMBO J 2020; 39:e104915. [PMID: 32557679 PMCID: PMC7396873 DOI: 10.15252/embj.2020104915] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Revised: 05/19/2020] [Accepted: 05/27/2020] [Indexed: 11/09/2022] Open
Abstract
In both plants and animals, nucleotide-binding leucine-rich repeat (NLR) immune receptors perceive pathogen-derived molecules to trigger immunity. Global NLR homeostasis must be tightly controlled to ensure sufficient and timely immune output while avoiding aberrant activation, the mechanisms of which are largely unclear. In a previous reverse genetic screen, we identified two novel E3 ligases, SNIPER1 and its homolog SNIPER2, both of which broadly control the levels of NLR immune receptors in Arabidopsis. Protein levels of sensor NLRs (sNLRs) are inversely correlated with SNIPER1 amount and the interactions between SNIPER1 and sNLRs seem to be through the common nucleotide-binding (NB) domains of sNLRs. In support, SNIPER1 can ubiquitinate the NB domains of multiple sNLRs in vitro. Our study thus reveals a novel process of global turnover of sNLRs by two master E3 ligases for immediate attenuation of immune output to effectively avoid autoimmunity. Such unique mechanism can be utilized in the future for engineering broad-spectrum resistance in crops to fend off pathogens that damage our food supply.
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Affiliation(s)
- Zhongshou Wu
- Michael Smith LaboratoriesUniversity of British ColumbiaVancouverBCCanada
- Department of BotanyUniversity of British ColumbiaVancouverBCCanada
| | - Meixuezi Tong
- Michael Smith LaboratoriesUniversity of British ColumbiaVancouverBCCanada
- Department of BotanyUniversity of British ColumbiaVancouverBCCanada
| | - Lei Tian
- Michael Smith LaboratoriesUniversity of British ColumbiaVancouverBCCanada
- Department of BotanyUniversity of British ColumbiaVancouverBCCanada
| | - Chipan Zhu
- Michael Smith LaboratoriesUniversity of British ColumbiaVancouverBCCanada
- Department of BotanyUniversity of British ColumbiaVancouverBCCanada
| | - Xueru Liu
- Michael Smith LaboratoriesUniversity of British ColumbiaVancouverBCCanada
- Department of BotanyUniversity of British ColumbiaVancouverBCCanada
| | - Yuelin Zhang
- Department of BotanyUniversity of British ColumbiaVancouverBCCanada
| | - Xin Li
- Michael Smith LaboratoriesUniversity of British ColumbiaVancouverBCCanada
- Department of BotanyUniversity of British ColumbiaVancouverBCCanada
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19
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Sun Y, Zhu YX, Balint-Kurti PJ, Wang GF. Fine-Tuning Immunity: Players and Regulators for Plant NLRs. TRENDS IN PLANT SCIENCE 2020; 25:695-713. [PMID: 32526174 DOI: 10.1016/j.tplants.2020.02.008] [Citation(s) in RCA: 59] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Revised: 02/11/2020] [Accepted: 02/14/2020] [Indexed: 05/20/2023]
Abstract
Plants have evolved a sophisticated innate immune system to defend against pathogen infection, and intracellular nucleotide-binding, leucine-rich repeat (NLR or NB-LRR) immune receptors are one of the main components of this system. NLR activity is fine-tuned by intra- and intermolecular interactions. We survey what is known about the conservation and diversity of NLR-interacting proteins, and divide them into seven major categories. We discuss the molecular mechanisms by which NLR activities are regulated and how understanding this regulation has potential to facilitate the engineering of NLRs for crop improvement.
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Affiliation(s)
- Yang Sun
- The Key Laboratory of Plant Development and Environmental Adaptation Biology, Ministry of Education, School of Life Sciences, Shandong University, Qingdao, Shandong 266237, PR China
| | - Yu-Xiu Zhu
- The Key Laboratory of Plant Development and Environmental Adaptation Biology, Ministry of Education, School of Life Sciences, Shandong University, Qingdao, Shandong 266237, PR China
| | - Peter J Balint-Kurti
- Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC 27695, USA; US Department of Agriculture Agricultural Research Service, Plant Science Research Unit, Raleigh, NC 27695, USA
| | - Guan-Feng Wang
- The Key Laboratory of Plant Development and Environmental Adaptation Biology, Ministry of Education, School of Life Sciences, Shandong University, Qingdao, Shandong 266237, PR China.
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20
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Structures of plant resistosome reveal how NLR immune receptors are activated. ABIOTECH 2020; 1:147-150. [PMID: 36304717 PMCID: PMC9590527 DOI: 10.1007/s42994-019-00012-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Accepted: 11/13/2019] [Indexed: 12/14/2022]
Abstract
Nucleotide-binding domain and leucine-rich repeat (NLR) proteins make up the largest immune receptor family in plants. Although many studies have put effort into revealing the working mechanism of NLRs, the activation details of plant NLRs still remain obscure. Recently, two remarkable works resolved the structures of a plant NLR protein, the Arabidopsis thaliana HOPZ-ACTIVATED RESISTANCE1 (ZAR1), both in resting and activation states. The activated ZAR1 with its partner proteins form a wheel-like pentamer called resistosome that is thought to be able to trigger cell death by perturbing plasma membrane integrity. These findings greatly further our understanding of plant immune system.
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21
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Li L, Habring A, Wang K, Weigel D. Atypical Resistance Protein RPW8/HR Triggers Oligomerization of the NLR Immune Receptor RPP7 and Autoimmunity. Cell Host Microbe 2020; 27:405-417.e6. [PMID: 32101702 DOI: 10.1016/j.chom.2020.01.012] [Citation(s) in RCA: 50] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Revised: 10/30/2019] [Accepted: 01/17/2020] [Indexed: 01/08/2023]
Abstract
In certain plant hybrids, immunity signaling is initiated when immune components interact in the absence of a pathogen trigger. In Arabidopsis thaliana, such autoimmunity and cell death are linked to variants of the NLR RPP7 and the RPW8 proteins involved in broad-spectrum resistance. We uncover the molecular basis for this autoimmunity and demonstrate that a homolog of RPW8, HR4Fei-0, can trigger the assembly of a higher-order RPP7 complex, with autoimmunity signaling as a consequence. HR4Fei-0-mediated RPP7 oligomerization occurs via the RPP7 C-terminal leucine-rich repeat (LRR) domain and ATP-binding P-loop. RPP7 forms a higher-order complex only in the presence of HR4Fei-0 and not with the standard HR4 variant, which is distinguished from HR4Fei-0 by length variation in C-terminal repeats. Additionally, HR4Fei-0 can independently form self-oligomers, which directly kill cells in an RPP7-independent manner. Our work provides evidence for a plant resistosome complex and the mechanisms by which RPW8/HR proteins trigger cell death.
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Affiliation(s)
- Lei Li
- Department of Molecular Biology, Max Planck Institute for Developmental Biology, 72076 Tübingen, Germany
| | - Anette Habring
- Department of Molecular Biology, Max Planck Institute for Developmental Biology, 72076 Tübingen, Germany
| | - Kai Wang
- Department of Cell Biology, Max Planck Institute for Developmental Biology, 72076 Tübingen, Germany
| | - Detlef Weigel
- Department of Molecular Biology, Max Planck Institute for Developmental Biology, 72076 Tübingen, Germany.
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22
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Feng B, Tang D. Mechanism of plant immune activation and signaling: Insight from the first solved plant resistosome structure. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2019; 61:902-907. [PMID: 30950566 DOI: 10.1111/jipb.12814] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Accepted: 04/01/2019] [Indexed: 06/09/2023]
Abstract
This commentary introduces an exciting breakthrough: the first solved structure of a plant NLR immune receptor complex. The significance of this work, including the similarity between the activation of NLRs from plants and animals, and potentially novel mechanism of immune signaling in plants, were discussed and put into perspective.
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Affiliation(s)
- Baomin Feng
- State Key Laboratory of Ecological Control of Fujian-Taiwan Crop Pests, Key Laboratory of Ministry of Education for Genetics, Breeding and Multiple Utilization of Crops, Plant Immunity Center, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Dingzhong Tang
- State Key Laboratory of Ecological Control of Fujian-Taiwan Crop Pests, Key Laboratory of Ministry of Education for Genetics, Breeding and Multiple Utilization of Crops, Plant Immunity Center, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
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23
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Wu Z, Li M, Dong OX, Xia S, Liang W, Bao Y, Wasteneys G, Li X. Differential regulation of TNL-mediated immune signaling by redundant helper CNLs. THE NEW PHYTOLOGIST 2019; 222:938-953. [PMID: 30585636 DOI: 10.1111/nph.15665] [Citation(s) in RCA: 129] [Impact Index Per Article: 25.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Accepted: 11/23/2018] [Indexed: 05/09/2023]
Abstract
Higher plants utilize nucleotide-binding leucine-rich repeat domain proteins (NLRs) as intracellular immune receptors to recognize pathogen-derived effectors and trigger a robust defense. The Activated Disease Resistance 1 (ADR1) family of coiled-coil NLRs (CNLs) have evolved as helper NLRs that function downstream of many TIR-type sensor NLRs (TNLs). Close homologs of ADR1s form the N REQUIREMENT GENE 1 (NRG1) family in Arabidopsis, the function of which is unclear. Through CRISPR/Cas9 gene editing methods, we discovered that the tandemly repeated NRG1A and NRG1B are functionally redundant and operate downstream of TNLs with differential strengths. Interestingly, ADR1s and NRG1s function in two distinct parallel pathways contributing to TNL-specific immunity. Synergistic effects on basal and TNL-mediated defense were detected among ADR1s and NRG1s. An intact P-loop of NRG1s is not required for mediating signals from sensor TNLs, whereas auto-active NRG1A exhibits autoimmunity. Importantly, NRG1s localize to the cytosol and endomembrane network regardless of the presence of effectors, suggesting a cytosolic activation mechanism. Taken together, different sensor TNLs differentially use two groups of helper NLRs, ADR1s and NRG1s, to transduce downstream defense signals.
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Affiliation(s)
- Zhongshou Wu
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
- Department of Botany, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
| | - Meng Li
- Department of Botany, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
| | - Oliver Xiaoou Dong
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
- Department of Botany, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
| | - Shitou Xia
- Hunan Provincial Key Laboratory of Phytohormones, Hunan Agricultural University, Changsha, 410128, China
| | - Wanwan Liang
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
- Department of Botany, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
| | - Yongkang Bao
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
| | - Geoffrey Wasteneys
- Department of Botany, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
| | - Xin Li
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
- Department of Botany, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
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24
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Kapos P, Devendrakumar KT, Li X. Plant NLRs: From discovery to application. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2019; 279:3-18. [PMID: 30709490 DOI: 10.1016/j.plantsci.2018.03.010] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Revised: 03/01/2018] [Accepted: 03/02/2018] [Indexed: 05/09/2023]
Abstract
Plants require a complex immune system to defend themselves against a wide range of pathogens which threaten their growth and development. The nucleotide-binding leucine-rich repeat proteins (NLRs) are immune sensors that recognize effectors delivered by pathogens. The first NLR was cloned more than twenty years ago. Since this initial discovery, NLRs have been described as key components of plant immunity responsible for pathogen recognition and triggering defense responses. They have now been described in most of the well-studied mulitcellular plant species, with most having large NLR repertoires. As research has progressed so has the understanding of how NLRs interact with their recognition substrates and how they in turn activate downstream signalling. It has also become apparent that NLR regulation occurs at the transcriptional, post-transcriptional, translational, and post-translational levels. Even before the first NLR was cloned, breeders were utilising such genes to increase crop performance. Increased understanding of the mechanistic details of the plant immune system enable the generation of plants resistant against devastating pathogens. This review aims to give an updated summary of the NLR field.
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Affiliation(s)
- Paul Kapos
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada; Department of Botany, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
| | - Karen Thulasi Devendrakumar
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada; Department of Botany, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
| | - Xin Li
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada; Department of Botany, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada.
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25
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Chakraborty J, Priya P, Dastidar SG, Das S. Physical interaction between nuclear accumulated CC-NB-ARC-LRR protein and WRKY64 promotes EDS1 dependent Fusarium wilt resistance in chickpea. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2018; 276:111-133. [PMID: 30348309 DOI: 10.1016/j.plantsci.2018.08.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2018] [Revised: 07/30/2018] [Accepted: 08/17/2018] [Indexed: 06/08/2023]
Abstract
Fusarium wilt is one of the most serious diseases affecting chickpea (Cicer arietinum L.). Here, we identified a putative Resistance Gene Analog (CaRGA) from chickpea, encoding a coiled-coil (CC) nucleotide-binding oligomerization domain (NB-ARC) containing leucine-rich repeat (LRR) protein (CC-NLR protein) that confers resistance against Fusarium oxysporum f. sp. ciceri race1 (Foc1). Over-expression and silencing of CaRGA in chickpea resulted in enhanced resistance and hyper-susceptibility, respectively against Foc1. Furthermore, defense response to Foc1 depends on CC-NLR interaction with WRKY64 transcription factor. CaRGA mediated wilt resistance largely compromised when WRKY64 was silenced. We also determined in planta intramolecular interactions and self-association of chickpea CC-NLR protein. The study shows CC domain suppressing auto-activation of the full-length CC-NLR protein in the absence of pathogen through self-inhibitory intramolecular interaction with NB-ARC domain, which is attenuated by self-interactions to LRR domain. Chickpea CC-NLR protein forms homocomplexes and then interacts with WRKY64. CC-NLR protein further phosphorylates WRKY64 thereby, ubiquitination and proteasome mediated degradation are protected. Phosphorylated WRKY64 with increased stability binds to EDS1 promoter and stimulates its transcription that induces in planta ectopic cell-death. The detailed analysis of CC-NLR and WRKY interactions provide a better understanding of the immune regulation by NLR proteins under biotic stresses.
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Affiliation(s)
- Joydeep Chakraborty
- Division of Plant Biology, Bose Institute, Centenary Campus, P-1/12, CIT Scheme-VIIM, Kankurgachi, Kolkata 700054, West Bengal, India.
| | - Prerna Priya
- Centre of Excellence in Bioinformatics, Bose Institute, Centenary Campus, P-1/12, CIT Scheme-VIIM, Kankurgachi, Kolkata 700054, West Bengal, India.
| | - Shubhra Ghosh Dastidar
- Centre of Excellence in Bioinformatics, Bose Institute, Centenary Campus, P-1/12, CIT Scheme-VIIM, Kankurgachi, Kolkata 700054, West Bengal, India.
| | - Sampa Das
- Division of Plant Biology, Bose Institute, Centenary Campus, P-1/12, CIT Scheme-VIIM, Kankurgachi, Kolkata 700054, West Bengal, India.
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Sun T, Liang W, Zhang Y, Li X. Negative regulation of resistance protein-mediated immunity by master transcription factors SARD1 and CBP60g. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2018; 60:1023-1027. [PMID: 30007010 DOI: 10.1111/jipb.12698] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Accepted: 07/10/2018] [Indexed: 06/08/2023]
Abstract
Salicylic acid (SA) is an essential defence hormone in plants. Upon pathogen infection, induced biosynthesis of SA is mediated by Isochorismate synthase 1 (ICS1), whose gene transcription is controlled mainly through two redundant transcription factors, SAR Deficient 1 (SARD1) and Calmodulin-binding protein 60-like g (CBP60g). Although these master transcription factors regulate not only positive, but also negative regulators of immunity, how they control signaling events downstream of different immune receptors is unclear. Using autoimmune mutants activating immunity mediated by different receptors we show that, although the sard1 cbp60g double mutant almost fully suppresses the activation of defence mediated by suppressor of npr1-1, constitutive 2 (snc2), it strikingly enhances snc1, which carries a gain-of-function mutation in an intracellular nucleotide-binding leucine-rich repeat (NLR) immune receptor. This negative regulation of immunity is achieved through the transcriptional regulation of negative regulators, such as Nudix hydrolase homolog 6 (NUDT6). Our study highlights the diverse roles, especially the negative ones, in the regulation of plant immunity by the two master immune transcription factors SARD1 and CBP60g.
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Affiliation(s)
- Tongjun Sun
- Department of Botany, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - Wanwan Liang
- Department of Botany, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - Yuelin Zhang
- Department of Botany, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - Xin Li
- Department of Botany, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
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27
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Dong OX, Ao K, Xu F, Johnson KCM, Wu Y, Li L, Xia S, Liu Y, Huang Y, Rodriguez E, Chen X, Chen S, Zhang Y, Petersen M, Li X. Individual components of paired typical NLR immune receptors are regulated by distinct E3 ligases. NATURE PLANTS 2018; 4:699-710. [PMID: 30082764 DOI: 10.1038/s41477-018-0216-8] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2016] [Accepted: 07/06/2018] [Indexed: 05/25/2023]
Abstract
In plants and animals, nucleotide-binding leucine-rich repeat (NLR) proteins serve as intracellular immune receptors. Defence signalling by NLRs often requires the formation of NLR heteropairs. Our knowledge of the molecular mechanism regulating this process is limited. In a reverse genetic screen to identify the partner of the Arabidopsis typical NLR, SUPRESSOR OF NPR1, CONSTITUTIVE 1 (SNC1), we discovered three NLRs that are redundantly required for SNC1-mediated defence, which were named SIDEKICK SNC1 1 (SIKIC1), SIKIC2 and SIKIC3. Immunoprecipitation-mass spectrometry analyses revealed that SIKIC2 physically associates with SNC1. We also uncovered that the protein level of SIKIC2 is under the control of two previously uncharacterized redundant E3 ubiquitin ligases MUSE1 and MUSE2. As SNC1 accumulation has previously been shown to be regulated by the E3 ubiquitin ligase SCFCPR1, this report provides evidence that the homeostasis of individual components of partnered typical NLRs is subjected to differential regulation via ubiquitin-mediated protein degradation.
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Affiliation(s)
- Oliver Xiaoou Dong
- Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Botany, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Plant Pathology, University of California, Davis, Davis, CA, USA
| | - Kevin Ao
- Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Botany, University of British Columbia, Vancouver, British Columbia, Canada
| | - Fang Xu
- Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Botany, University of British Columbia, Vancouver, British Columbia, Canada
- Cold Spring Harbor Laboratory, Cold Spring Harbor, New York, NY, USA
| | - Kaeli C M Johnson
- Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Botany, University of British Columbia, Vancouver, British Columbia, Canada
| | - Yuxiang Wu
- Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia, Canada
- College of Agriculture, Shanxi Agriculture University, Jinzhong, China
| | - Lin Li
- National Institute of Biological Sciences, Beijing, China
| | - Shitou Xia
- Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia, Canada
- Hunan Provincial Key Laboratory of Phytohormones and Growth Development, Hunan Agricultural University, Changsha, China
| | - Yanan Liu
- Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Botany, University of British Columbia, Vancouver, British Columbia, Canada
| | - Yan Huang
- Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Botany, University of British Columbia, Vancouver, British Columbia, Canada
- College of Life Science, Sichuan Agricultural University, Ya'an, China
| | - Eleazar Rodriguez
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Xuejin Chen
- Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia, Canada
| | - She Chen
- Hunan Provincial Key Laboratory of Phytohormones and Growth Development, Hunan Agricultural University, Changsha, China
| | - Yuelin Zhang
- Department of Botany, University of British Columbia, Vancouver, British Columbia, Canada
| | - Morten Petersen
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Xin Li
- Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia, Canada.
- Department of Botany, University of British Columbia, Vancouver, British Columbia, Canada.
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28
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Lim SD, Yim WC, Liu D, Hu R, Yang X, Cushman JC. A Vitis vinifera basic helix-loop-helix transcription factor enhances plant cell size, vegetative biomass and reproductive yield. PLANT BIOTECHNOLOGY JOURNAL 2018; 16:1595-1615. [PMID: 29520945 PMCID: PMC6096725 DOI: 10.1111/pbi.12898] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2017] [Accepted: 01/22/2018] [Indexed: 05/03/2023]
Abstract
Strategies for improving plant size are critical targets for plant biotechnology to increase vegetative biomass or reproductive yield. To improve biomass production, a codon-optimized helix-loop-helix transcription factor (VvCEB1opt ) from wine grape was overexpressed in Arabidopsis thaliana resulting in significantly increased leaf number, leaf and rosette area, fresh weight and dry weight. Cell size, but typically not cell number, was increased in all tissues resulting in increased vegetative biomass and reproductive organ size, number and seed yield. Ionomic analysis of leaves revealed the VvCEB1opt -overexpressing plants had significantly elevated, K, S and Mo contents relative to control lines. Increased K content likely drives increased osmotic potential within cells leading to greater cellular growth and expansion. To understand the mechanistic basis of VvCEB1opt action, one transgenic line was genotyped using RNA-Seq mRNA expression profiling and revealed a novel transcriptional reprogramming network with significant changes in mRNA abundance for genes with functions in delayed flowering, pathogen-defence responses, iron homeostasis, vesicle-mediated cell wall formation and auxin-mediated signalling and responses. Direct testing of VvCEB1opt -overexpressing plants showed that they had significantly elevated auxin content and a significantly increased number of lateral leaf primordia within meristems relative to controls, confirming that cell expansion and organ number proliferation were likely an auxin-mediated process. VvCEB1opt overexpression in Nicotiana sylvestris also showed larger cells, organ size and biomass demonstrating the potential applicability of this innovative strategy for improving plant biomass and reproductive yield in crops.
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Affiliation(s)
- Sung Don Lim
- Department of Biochemistry and Molecular BiologyUniversity of Nevada, RenoRenoNVUSA
| | - Won Choel Yim
- Department of Biochemistry and Molecular BiologyUniversity of Nevada, RenoRenoNVUSA
| | - Degao Liu
- Biosciences DivisionOak Ridge National LaboratoryOak RidgeTNUSA
| | - Rongbin Hu
- Biosciences DivisionOak Ridge National LaboratoryOak RidgeTNUSA
| | - Xiaohan Yang
- Biosciences DivisionOak Ridge National LaboratoryOak RidgeTNUSA
| | - John C. Cushman
- Department of Biochemistry and Molecular BiologyUniversity of Nevada, RenoRenoNVUSA
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29
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Feng H, Xu M, Zheng X, Zhu T, Gao X, Huang L. microRNAs and Their Targets in Apple ( Malus domestica cv. "Fuji") Involved in Response to Infection of Pathogen Valsa mali. FRONTIERS IN PLANT SCIENCE 2017; 8:2081. [PMID: 29270184 PMCID: PMC5723928 DOI: 10.3389/fpls.2017.02081] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Accepted: 11/21/2017] [Indexed: 05/19/2023]
Abstract
miRNAs are important regulators involving in plant-pathogen interactions. However, their roles in apple tree response to Valsa canker pathogen (Valsa mali, Vm) infection were poorly understood. In this study, we constructed two miRNA libraries using the twig bark tissues of apple tree (Malus domestica Borkh. cv. "Fuji") inoculated with Vm (IVm) and PDA medium (control, BMd). Among all detected miRNAs, 23 miRNAs were specifically isolated from BMd and 39 miRNAs were specifically isolated from IVm. Meanwhile, the expression of 294 miRNAs decreased; and another 172 miRNAs showed an increased expression trend in IVm compared with that in BMd. Furthermore, two degradome sequencing libraries were also constructed to identify the target genes of these miRNAs. In total, 353 differentially expressed miRNAs between IVm and BMd were detected to be able to target 1,077 unigenes with 2,251 cleavage sites. Based on GO and KEGG analysis, these genes were found to be mainly related to transcription regulation and signal transduction. In addition, we selected 17 miRNAs and 22 corresponding target genes to screen the expression profiles when apple twigs were infected by Vm. The expression trends of most miRNAs/target genes were consist with the results of deep sequencing. Many of them may involve in the apple twig-Vm interaction by inducing/reducing their expression. What's more, miRNAs and their target genes regulate the apple twig-Vm interaction by forming many complicated regulation networks rather than one to one model. It is worth that a conserved miRNAs mdm-miR482b, which was down regulated in IVm compared with BMd, has 14 potential target genes, most of which are disease resistance related genes. This indicates that mdm-miR482b may play important roles in apple twig response to Vm. More important, the feedback regulation of sRNA pathway in apple twig is also very complex, and play critical role in the interaction between apple twig and Vm based on the results of expression analysis. In all, the results will provide insights into the crucial functions of miRNAs in the woody plant, apple tree-Vm interaction.
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Affiliation(s)
| | | | | | | | | | - Lili Huang
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Plant Protection, Northwest A&F University, Yangling, China
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30
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Tong M, Kotur T, Liang W, Vogelmann K, Kleine T, Leister D, Brieske C, Yang S, Lüdke D, Wiermer M, Zhang Y, Li X, Hoth S. E3 ligase SAUL1 serves as a positive regulator of PAMP-triggered immunity and its homeostasis is monitored by immune receptor SOC3. THE NEW PHYTOLOGIST 2017; 215:1516-1532. [PMID: 28691210 DOI: 10.1111/nph.14678] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Accepted: 05/26/2017] [Indexed: 05/08/2023]
Abstract
In both plants and animals, intracellular nucleotide-binding leucine-rich repeat proteins (NLRs; or Nod-like receptors) serve as immune receptors to recognize pathogen-derived molecules and mount effective immune responses against microbial infections. Plant NLRs often guard the presence or activity of other host proteins, which are the direct virulence targets of pathogen effectors. These guardees are sometimes immune-promoting components such as those in a mitogen-activated protein kinase cascade. Plant E3 ligases serve many roles in immune regulation, but it is unclear whether they can also be guarded by NLRs. Here, we report on an immune-regulating E3 ligase SAUL1, whose homeostasis is monitored by a Toll interleukin 1 receptor (TIR)-type NLR (TNL), SOC3. SOC3 can associate with SAUL1, and either loss or overexpression of SAUL1 triggers autoimmunity mediated by SOC3. By contrast, SAUL1 functions redundantly with its close homolog PUB43 to promote PAMP-triggered immunity (PTI). Taken together, the E3 ligase SAUL1 serves as a positive regulator of PTI and its homeostasis is monitored by the TNL SOC3.
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Affiliation(s)
- Meixuezi Tong
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
- Department of Botany, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
| | - Tanja Kotur
- Molekulare Pflanzenphysiologie, Biozentrum Klein Flottbek, Universität Hamburg, 22609, Hamburg, Germany
| | - Wanwan Liang
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
- Department of Botany, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
| | - Katja Vogelmann
- Molekulare Pflanzenphysiologie, Biozentrum Klein Flottbek, Universität Hamburg, 22609, Hamburg, Germany
| | - Tatjana Kleine
- Plant Molecular Biology (Botany), Department Biology I, Ludwig-Maximilians-Universität München, 82152, Planegg-Martinsried, Germany
| | - Dario Leister
- Plant Molecular Biology (Botany), Department Biology I, Ludwig-Maximilians-Universität München, 82152, Planegg-Martinsried, Germany
| | - Catharina Brieske
- Molekulare Pflanzenphysiologie, Biozentrum Klein Flottbek, Universität Hamburg, 22609, Hamburg, Germany
| | - Shuhua Yang
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Daniel Lüdke
- RG Molecular Biology of Plant-Microbe Interactions, Albrecht-von-Haller-Institute for Plant Sciences, University of Goettingen, Julia-Lermontowa-Weg 3, 37077, Goettingen, Germany
| | - Marcel Wiermer
- RG Molecular Biology of Plant-Microbe Interactions, Albrecht-von-Haller-Institute for Plant Sciences, University of Goettingen, Julia-Lermontowa-Weg 3, 37077, Goettingen, Germany
| | - Yuelin Zhang
- Department of Botany, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
| | - Xin Li
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
- Department of Botany, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
| | - Stefan Hoth
- Molekulare Pflanzenphysiologie, Biozentrum Klein Flottbek, Universität Hamburg, 22609, Hamburg, Germany
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31
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El Kasmi F, Chung EH, Anderson RG, Li J, Wan L, Eitas TK, Gao Z, Dangl JL. Signaling from the plasma-membrane localized plant immune receptor RPM1 requires self-association of the full-length protein. Proc Natl Acad Sci U S A 2017; 114:E7385-E7394. [PMID: 28808003 PMCID: PMC5584451 DOI: 10.1073/pnas.1708288114] [Citation(s) in RCA: 80] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Plants evolved intracellular immune receptors that belong to the NOD-like receptor (NLR) family to recognize the presence of pathogen-derived effector proteins. NLRs possess an N-terminal Toll-like/IL-1 receptor (TIR) or a non-TIR domain [some of which contain coiled coils (CCs)], a central nucleotide-binding (NB-ARC) domain, and a C-terminal leucine-rich repeat (LRR). Activation of NLR proteins results in a rapid and high-amplitude immune response, eventually leading to host cell death at the infection site, the so-called hypersensitive response. Despite their important contribution to immunity, the exact mechanisms of NLR activation and signaling remain unknown and are likely heterogenous. We undertook a detailed structure-function analysis of the plasma membrane (PM)-localized CC NLR Resistance to Pseudomonas syringae pv. maculicola 1 (RPM1) using both stable transgenic Arabidopsis and transient expression in Nicotiana benthamiana We report that immune signaling is induced only by activated full-length PM-localized RPM1. Our interaction analyses demonstrate the importance of a functional P-loop for in planta interaction of RPM1 with the small host protein RPM1-interacting protein 4 (RIN4), for constitutive preactivation and postactivation self-association of RPM1 and for proper PM localization. Our results reveal an additive effect of hydrophobic conserved residues in the CC domain for RPM1 function and RPM1 self-association and their necessity for RPM1-RIN4 interaction. Thus, our findings considerably extend our understanding of the mechanisms regulating NLR activation at, and signaling from, the PM.
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Affiliation(s)
- Farid El Kasmi
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3280
| | - Eui-Hwan Chung
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3280
- Howard Hughes Medical Institute, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3280
| | - Ryan G Anderson
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3280
| | - Jinyue Li
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, Hubei Province, P. R. China 430072
| | - Li Wan
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3280
| | - Timothy K Eitas
- Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3280
| | - Zhiyong Gao
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, Hubei Province, P. R. China 430072;
| | - Jeffery L Dangl
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3280;
- Howard Hughes Medical Institute, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3280
- Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3280
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3280
- Carolina Center for Genome Sciences, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3280
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32
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Abstract
The first plant disease resistance (R) genes were identified and cloned more than two decades ago. Since then, many more R genes have been identified and characterized in numerous plant pathosystems. Most of these encode members of the large family of intracellular NLRs (NOD-like receptors), which also includes animal immune receptors. New discoveries in this expanding field of research provide new elements for our understanding of plant NLR function. But what do we know about plant NLR function today? Genetic, structural, and functional analyses have uncovered a number of commonalities and differences in pathogen recognition strategies as well as how NLRs are regulated and activate defense signaling, but many unknowns remain. This review gives an update on the latest discoveries and breakthroughs in this field, with an emphasis on structural findings and some comparison to animal NLRs, which can provide additional insights and paradigms in plant NLR function.
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Affiliation(s)
- Xiaoxiao Zhang
- Commonwealth Scientific and Industrial Research Organisation, Agriculture and Food, Canberra, ACT 2601, Australia;
| | - Peter N Dodds
- Commonwealth Scientific and Industrial Research Organisation, Agriculture and Food, Canberra, ACT 2601, Australia;
| | - Maud Bernoux
- Commonwealth Scientific and Industrial Research Organisation, Agriculture and Food, Canberra, ACT 2601, Australia;
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33
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Huh SU, Cevik V, Ding P, Duxbury Z, Ma Y, Tomlinson L, Sarris PF, Jones JDG. Protein-protein interactions in the RPS4/RRS1 immune receptor complex. PLoS Pathog 2017; 13:e1006376. [PMID: 28475615 PMCID: PMC5435354 DOI: 10.1371/journal.ppat.1006376] [Citation(s) in RCA: 84] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Revised: 05/17/2017] [Accepted: 04/25/2017] [Indexed: 11/18/2022] Open
Abstract
Plant NLR (Nucleotide-binding domain and Leucine-rich Repeat) immune receptor proteins are encoded by Resistance (R) genes and confer specific resistance to pathogen races that carry the corresponding recognized effectors. Some NLR proteins function in pairs, forming receptor complexes for the perception of specific effectors. We show here that the Arabidopsis RPS4 and RRS1 NLR proteins are both required to make an authentic immune complex. Over-expression of RPS4 in tobacco or in Arabidopsis results in constitutive defense activation; this phenotype is suppressed in the presence of RRS1. RRS1 protein co-immunoprecipitates (co-IPs) with itself in the presence or absence of RPS4, but in contrast, RPS4 does not associate with itself in the absence of RRS1. In the presence of RRS1, RPS4 associates with defense signaling regulator EDS1 solely in the nucleus, in contrast to the extra-nuclear location found in the absence of RRS1. The AvrRps4 effector does not disrupt RPS4-EDS1 association in the presence of RRS1. In the absence of RRS1, AvrRps4 interacts with EDS1, forming nucleocytoplasmic aggregates, the formation of which is disturbed by the co-expression of PAD4 but not by SAG101. These data indicate that the study of an immune receptor protein complex in the absence of all components can result in misleading inferences, and reveals an NLR complex that dynamically interacts with the immune regulators EDS1/PAD4 or EDS1/SAG101, and with effectors, during the process by which effector recognition is converted to defense activation.
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Affiliation(s)
- Sung Un Huh
- The Sainsbury Laboratory, Norwich Research Park, Colney Lane, Norwich, United Kingdom
| | - Volkan Cevik
- The Sainsbury Laboratory, Norwich Research Park, Colney Lane, Norwich, United Kingdom
- Department of Biology and Biochemistry, University of Bath, Bath, United Kingdom
| | - Pingtao Ding
- The Sainsbury Laboratory, Norwich Research Park, Colney Lane, Norwich, United Kingdom
| | - Zane Duxbury
- The Sainsbury Laboratory, Norwich Research Park, Colney Lane, Norwich, United Kingdom
| | - Yan Ma
- The Sainsbury Laboratory, Norwich Research Park, Colney Lane, Norwich, United Kingdom
| | - Laurence Tomlinson
- The Sainsbury Laboratory, Norwich Research Park, Colney Lane, Norwich, United Kingdom
| | - Panagiotis F. Sarris
- Department of Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter, United Kingdom
| | - Jonathan D. G. Jones
- The Sainsbury Laboratory, Norwich Research Park, Colney Lane, Norwich, United Kingdom
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34
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Huang S, Balgi A, Pan Y, Li M, Zhang X, Du L, Zhou M, Roberge M, Li X. Identification of Methylosome Components as Negative Regulators of Plant Immunity Using Chemical Genetics. MOLECULAR PLANT 2016; 9:1620-1633. [PMID: 27756575 DOI: 10.1016/j.molp.2016.10.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2016] [Revised: 09/01/2016] [Accepted: 10/01/2016] [Indexed: 06/06/2023]
Abstract
Nucleotide-binding leucine-rich repeat (NLR) proteins serve as immune receptors in both plants and animals. To identify components required for NLR-mediated immunity, we designed and carried out a chemical genetics screen to search for small molecules that can alter immune responses in Arabidopsis thaliana. From 13 600 compounds, we identified Ro 8-4304 that was able to specifically suppress the severe autoimmune phenotypes of chs3-2D (chilling sensitive 3, 2D), including the arrested growth morphology and heightened PR (Pathogenesis Related) gene expression. Further, six Ro 8-4304 insensitive mutants were uncovered from the Ro 8-4304-insensitive mutant (rim) screen using a mutagenized chs3-2D population. Positional cloning revealed that rim1 encodes an allele of AtICln (I, currents; Cl, chloride; n, nucleotide). Genetic and biochemical analysis demonstrated that AtICln is in the same protein complex with the methylosome components small nuclear ribonucleoprotein D3b (SmD3b) and protein arginine methyltransferase 5 (PRMT5), which are required for the biogenesis of small nuclear ribonucleoproteins (snRNPs) involved in mRNA splicing. Double mutant analysis revealed that SmD3b is also involved in the sensitivity to Ro 8-4304, and the prmt5-1 chs3-2D double mutant is lethal. Loss of AtICln, SmD3b, or PRMT5 function results in enhanced disease resistance against the virulent oomycete pathogen Hyaloperonospora arabidopsidis Noco2, suggesting that mRNA splicing plays a previously unknown negative role in plant immunity. The successful implementation of a high-throughput chemical genetic screen and the identification of a small-molecule compound affecting plant immunity indicate that chemical genetics is a powerful tool to study whole-organism plant defense pathways.
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Affiliation(s)
- Shuai Huang
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC V6T 1Z4, Canada; Department of Botany, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - Aruna Balgi
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Yaping Pan
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Meng Li
- Department of Botany, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - Xiaoran Zhang
- National Institute of Biological Sciences, Beijing 102206, China
| | - Lilin Du
- National Institute of Biological Sciences, Beijing 102206, China
| | - Ming Zhou
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Michel Roberge
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Xin Li
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC V6T 1Z4, Canada; Department of Botany, University of British Columbia, Vancouver, BC V6T 1Z4, Canada.
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35
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Huang S, Chen X, Zhong X, Li M, Ao K, Huang J, Li X. Plant TRAF Proteins Regulate NLR Immune Receptor Turnover. Cell Host Microbe 2016; 19:204-15. [PMID: 26867179 DOI: 10.1016/j.chom.2016.01.005] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Revised: 12/03/2015] [Accepted: 01/20/2016] [Indexed: 11/18/2022]
Abstract
In animals, Tumor necrosis factor receptor-associated factor (TRAF) proteins are molecular adaptors that regulate innate and adaptive immunity, development, and abiotic stress responses. Although gene families encoding TRAF domain-containing proteins exhibit enriched diversity in higher plants, their biological roles are poorly defined. Here, we report the identification of two redundant TRAF proteins, Mutant, snc1-enhancing 13 (MUSE13) and MUSE14, that contribute to the turnover of nucleotide-binding domain and leucine-rich repeat-containing (NLR) immune receptors SNC1 and RPS2. Loss of both MUSE13 and MUSE14 leads to enhanced pathogen resistance, NLR accumulation, and autoimmunity, while MUSE13 overexpression results in reduced NLR levels and activity. In planta, MUSE13 associates with SNC1, RPS2, and the E3 ubiquitin ligase SCF(CPR1). Taken together, we speculate that MUSE13 and MUSE14 associate with the SCF E3 ligase complex to form a plant-type TRAFasome, which modulates ubiquitination and subsequent degradation of NLR immune sensors to maintain their homeostasis.
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Affiliation(s)
- Shuai Huang
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC V6T 1Z4, Canada; Department of Botany, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - Xuejin Chen
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC V6T 1Z4, Canada; College of Horticulture, Northwest A&F University, Yangling 712100, Shaanxi, China
| | - Xionghui Zhong
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC V6T 1Z4, Canada; Department of Botany, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - Meng Li
- Department of Botany, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - Kevin Ao
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC V6T 1Z4, Canada; Department of Botany, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - Jianhua Huang
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC V6T 1Z4, Canada; Department of Botany, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - Xin Li
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC V6T 1Z4, Canada; Department of Botany, University of British Columbia, Vancouver, BC V6T 1Z4, Canada.
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Duxbury Z, Ma Y, Furzer OJ, Huh SU, Cevik V, Jones JDG, Sarris PF. Pathogen perception by NLRs in plants and animals: Parallel worlds. Bioessays 2016; 38:769-81. [PMID: 27339076 DOI: 10.1002/bies.201600046] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Intracellular NLR (Nucleotide-binding domain and Leucine-rich Repeat-containing) receptors are sensitive monitors that detect pathogen invasion of both plant and animal cells. NLRs confer recognition of diverse molecules associated with pathogen invasion. NLRs must exhibit strict intramolecular controls to avoid harmful ectopic activation in the absence of pathogens. Recent discoveries have elucidated the assembly and structure of oligomeric NLR signalling complexes in animals, and provided insights into how these complexes act as scaffolds for signal transduction. In plants, recent advances have provided novel insights into signalling-competent NLRs, and into the myriad strategies that diverse plant NLRs use to recognise pathogens. Here, we review recent insights into the NLR biology of both animals and plants. By assessing commonalities and differences between kingdoms, we are able to develop a more complete understanding of NLR function.
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Affiliation(s)
- Zane Duxbury
- The Sainsbury Laboratory, Norwich Research Park, Norwich, UK
| | - Yan Ma
- The Sainsbury Laboratory, Norwich Research Park, Norwich, UK
| | - Oliver J Furzer
- The Sainsbury Laboratory, Norwich Research Park, Norwich, UK
| | - Sung Un Huh
- The Sainsbury Laboratory, Norwich Research Park, Norwich, UK
| | - Volkan Cevik
- The Sainsbury Laboratory, Norwich Research Park, Norwich, UK
| | | | - Panagiotis F Sarris
- Division of Plant and Microbial Sciences, School of Biosciences, University of Exeter, Exeter, UK
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Dong OX, Tong M, Bonardi V, El Kasmi F, Woloshen V, Wünsch LK, Dangl JL, Li X. TNL-mediated immunity in Arabidopsis requires complex regulation of the redundant ADR1 gene family. THE NEW PHYTOLOGIST 2016; 210:960-973. [PMID: 27074399 DOI: 10.1111/nph.13821] [Citation(s) in RCA: 66] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2015] [Accepted: 11/24/2015] [Indexed: 06/05/2023]
Abstract
Nucleotide-binding leucine-rich repeat proteins (NLRs) serve as intracellular immune receptors in animals and plants. Sensor NLRs perceive pathogen-derived effector molecules and trigger robust host defense. Recent studies revealed the role of three coiled-coil-type NLRs (CNLs) of the ADR1 family - ADR1, ADR1-L1 and ADR1-L2 - as redundant helper NLRs, whose function is required for defense mediated by multiple sensor NLRs. From a mutant snc1-enhancing (MUSE) forward genetic screen in Arabidopsis targeted to identify negative regulators of snc1 that encodes a TIR-type NLR (TNL), we isolated two alleles of muse15, both carrying mutations in ADR1-L1. Interestingly, loss of ADR1-L1 also enhances immunity-related phenotypes in other autoimmune mutants including cpr1, bal and lsd1. This immunity-enhancing effect is not mediated by increased SNC1 protein stability, nor is it fully dependent on the accumulation of the defense hormone salicylic acid (SA). Transcriptional analysis revealed an upregulation of ADR1 and ADR1-L2 in the adr1-L1 background, which may overcompensate the loss of ADR1-L1, resulting in enhanced immunity. Interestingly, autoimmunity of snc1 and chs2, which encode typical TNLs, is fully suppressed by the adr1 triple mutant, suggesting that the ADRs are required for TNL downstream signaling. This study extends our knowledge on the interplay among ADRs and reveals their complexity in defense regulation.
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Affiliation(s)
- Oliver Xiaoou Dong
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
- Department of Botany, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
| | - Meixuezi Tong
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
- Department of Botany, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
| | - Vera Bonardi
- Department of Biology, University of North Carolina, Chapel Hill, NC, 27599-3280, USA
| | - Farid El Kasmi
- Department of Biology, University of North Carolina, Chapel Hill, NC, 27599-3280, USA
| | - Virginia Woloshen
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
- Department of Botany, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
| | - Lisa K Wünsch
- Department of Biology, University of North Carolina, Chapel Hill, NC, 27599-3280, USA
| | - Jeffery L Dangl
- Department of Biology, University of North Carolina, Chapel Hill, NC, 27599-3280, USA
- Howard Hughes Medical Institute, University of North Carolina, Chapel Hill, NC, 27599-3280, USA
| | - Xin Li
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
- Department of Botany, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
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Abstract
Intracellular immune receptors with nucleotide-binding, leucine-rich domains (NLRs) are found in both plants and animals. Compared to animals, NLR-encoding gene families are expanded, more prevalent and have enriched diversity in higher plants. Strong host defense triggered by the recognition of specific pathogen effectors constitutes a major part of the plant immune response that has long been exploited to breed crops for enhanced resistance. Although the first plant NLR genes were cloned about 20 years ago, their signaling mechanisms remain obscure. Here we review recent progress in plant NLR studies, focusing on their pathogen recognition, homeostasis control and potential signaling activation mechanisms.
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