101
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Lee HA, Yeom SI. Plant NB-LRR proteins: tightly regulated sensors in a complex manner. Brief Funct Genomics 2015; 14:233-42. [DOI: 10.1093/bfgp/elv012] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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102
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Wang GF, Ji J, EI-Kasmi F, Dangl JL, Johal G, Balint-Kurti PJ. Molecular and functional analyses of a maize autoactive NB-LRR protein identify precise structural requirements for activity. PLoS Pathog 2015; 11:e1004674. [PMID: 25719542 PMCID: PMC4342346 DOI: 10.1371/journal.ppat.1004674] [Citation(s) in RCA: 89] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Accepted: 01/09/2015] [Indexed: 12/22/2022] Open
Abstract
Plant disease resistance is often mediated by nucleotide binding-leucine rich repeat (NLR) proteins which remain auto-inhibited until recognition of specific pathogen-derived molecules causes their activation, triggering a rapid, localized cell death called a hypersensitive response (HR). Three domains are recognized in one of the major classes of NLR proteins: a coiled-coil (CC), a nucleotide binding (NB-ARC) and a leucine rich repeat (LRR) domains. The maize NLR gene Rp1-D21 derives from an intergenic recombination event between two NLR genes, Rp1-D and Rp1-dp2 and confers an autoactive HR. We report systematic structural and functional analyses of Rp1 proteins in maize and N. benthamiana to characterize the molecular mechanism of NLR activation/auto-inhibition. We derive a model comprising the following three main features: Rp1 proteins appear to self-associate to become competent for activity. The CC domain is signaling-competent and is sufficient to induce HR. This can be suppressed by the NB-ARC domain through direct interaction. In autoactive proteins, the interaction of the LRR domain with the NB-ARC domain causes de-repression and thus disrupts the inhibition of HR. Further, we identify specific amino acids and combinations thereof that are important for the auto-inhibition/activity of Rp1 proteins. We also provide evidence for the function of MHD2, a previously uncharacterized, though widely conserved NLR motif. This work reports several novel insights into the precise structural requirement for NLR function and informs efforts towards utilizing these proteins for engineering disease resistance.
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Affiliation(s)
- Guan-Feng Wang
- Department of Plant Pathology, North Carolina State University, Raleigh, North Carolina, United States of America
- * E-mail: (GFW); (PJBK)
| | - Jiabing Ji
- Botany and Plant Pathology, Purdue University, West Lafayette, Indiana, United States of America
| | - Farid EI-Kasmi
- Department of Biology, University of North Carolina, Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Jeffery L. Dangl
- Department of Biology and Howard Hughes Medical Institute, Curriculum in Genetics and Molecular Biology, Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Guri Johal
- Botany and Plant Pathology, Purdue University, West Lafayette, Indiana, United States of America
| | - Peter J. Balint-Kurti
- Department of Plant Pathology, North Carolina State University, Raleigh, North Carolina, United States of America
- USDA-ARS Plant Science Research Unit, Raleigh, North Carolina, United States of America
- * E-mail: (GFW); (PJBK)
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103
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Munch D, Teh OK, Malinovsky FG, Liu Q, Vetukuri RR, El Kasmi F, Brodersen P, Hara-Nishimura I, Dangl JL, Petersen M, Mundy J, Hofius D. Retromer contributes to immunity-associated cell death in Arabidopsis. THE PLANT CELL 2015; 27:463-79. [PMID: 25681156 PMCID: PMC4456924 DOI: 10.1105/tpc.114.132043] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Membrane trafficking is required during plant immune responses, but its contribution to the hypersensitive response (HR), a form of programmed cell death (PCD) associated with effector-triggered immunity, is not well understood. HR is induced by nucleotide binding-leucine-rich repeat (NB-LRR) immune receptors and can involve vacuole-mediated processes, including autophagy. We previously isolated lazarus (laz) suppressors of autoimmunity-triggered PCD in the Arabidopsis thaliana mutant accelerated cell death11 (acd11) and demonstrated that the cell death phenotype is due to ectopic activation of the LAZ5 NB-LRR. We report here that laz4 is mutated in one of three VACUOLAR PROTEIN SORTING35 (VPS35) genes. We verify that LAZ4/VPS35B is part of the retromer complex, which functions in endosomal protein sorting and vacuolar trafficking. We show that VPS35B acts in an endosomal trafficking pathway and plays a role in LAZ5-dependent acd11 cell death. Furthermore, we find that VPS35 homologs contribute to certain forms of NB-LRR protein-mediated autoimmunity as well as pathogen-triggered HR. Finally, we demonstrate that retromer deficiency causes defects in late endocytic/lytic compartments and impairs autophagy-associated vacuolar processes. Our findings indicate important roles of retromer-mediated trafficking during the HR; these may include endosomal sorting of immune components and targeting of vacuolar cargo.
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Affiliation(s)
- David Munch
- Department of Biology, Copenhagen University, Copenhagen 2200, Denmark
| | - Ooi-Kock Teh
- Department of Plant Biology, Uppsala BioCenter, Swedish University of Agricultural Sciences and Linnean Center of Plant Biology, SE-75007 Uppsala, Sweden
| | | | - Qinsong Liu
- Department of Plant Biology, Uppsala BioCenter, Swedish University of Agricultural Sciences and Linnean Center of Plant Biology, SE-75007 Uppsala, Sweden
| | - Ramesh R Vetukuri
- Department of Plant Biology, Uppsala BioCenter, Swedish University of Agricultural Sciences and Linnean Center of Plant Biology, SE-75007 Uppsala, Sweden
| | - Farid El Kasmi
- Howard Hughes Medical Institute, Department of Biology, and Carolina Center for Genome Sciences, University of North Carolina, Chapel Hill, North Carolina 27599-3280
| | - Peter Brodersen
- Department of Biology, Copenhagen University, Copenhagen 2200, Denmark
| | - Ikuko Hara-Nishimura
- Department of Botany, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | - Jeffery L Dangl
- Howard Hughes Medical Institute, Department of Biology, and Carolina Center for Genome Sciences, University of North Carolina, Chapel Hill, North Carolina 27599-3280
| | - Morten Petersen
- Department of Biology, Copenhagen University, Copenhagen 2200, Denmark
| | - John Mundy
- Department of Biology, Copenhagen University, Copenhagen 2200, Denmark
| | - Daniel Hofius
- Department of Biology, Copenhagen University, Copenhagen 2200, Denmark Department of Plant Biology, Uppsala BioCenter, Swedish University of Agricultural Sciences and Linnean Center of Plant Biology, SE-75007 Uppsala, Sweden
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104
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Cui H, Tsuda K, Parker JE. Effector-triggered immunity: from pathogen perception to robust defense. ANNUAL REVIEW OF PLANT BIOLOGY 2015; 66:487-511. [PMID: 25494461 DOI: 10.1146/annurev-arplant-050213-040012] [Citation(s) in RCA: 757] [Impact Index Per Article: 84.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
In plant innate immunity, individual cells have the capacity to sense and respond to pathogen attack. Intracellular recognition mechanisms have evolved to intercept perturbations by pathogen virulence factors (effectors) early in host infection and convert it to rapid defense. One key to resistance success is a polymorphic family of intracellular nucleotide-binding/leucine-rich-repeat (NLR) receptors that detect effector interference in different parts of the cell. Effector-activated NLRs connect, in various ways, to a conserved basal resistance network in order to transcriptionally boost defense programs. Effector-triggered immunity displays remarkable robustness against pathogen disturbance, in part by employing compensatory mechanisms within the defense network. Also, the mobility of some NLRs and coordination of resistance pathways across cell compartments provides flexibility to fine-tune immune outputs. Furthermore, a number of NLRs function close to the nuclear chromatin by balancing actions of defense-repressing and defense-activating transcription factors to program cells dynamically for effective disease resistance.
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Affiliation(s)
- Haitao Cui
- Department of Plant-Microbe Interactions, Max Planck Institute for Plant Breeding Research, 50829 Cologne, Germany; , ,
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105
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Choi DS, Kim NH, Hwang BK. Pepper mitochondrial FORMATE DEHYDROGENASE1 regulates cell death and defense responses against bacterial pathogens. PLANT PHYSIOLOGY 2014; 166:1298-311. [PMID: 25237129 PMCID: PMC4226358 DOI: 10.1104/pp.114.246736] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Formate dehydrogenase (FDH; EC 1.2.1.2) is an NAD-dependent enzyme that catalyzes the oxidation of formate to carbon dioxide. Here, we report the identification and characterization of pepper (Capsicum annuum) mitochondrial FDH1 as a positive regulator of cell death and defense responses. Transient expression of FDH1 caused hypersensitive response (HR)-like cell death in pepper and Nicotiana benthamiana leaves. The D-isomer -: specific 2-hydroxyacid dehydrogenase signatures of FDH1 were required for the induction of HR-like cell death and FDH activity. FDH1 contained a mitochondrial targeting sequence at the N-terminal region; however, mitochondrial localization of FDH1 was not essential for the induction of HR-like cell death and FDH activity. FDH1 silencing in pepper significantly attenuated the cell death response and salicylic acid levels but stimulated growth of Xanthomonas campestris pv vesicatoria. By contrast, transgenic Arabidopsis (Arabidopsis thaliana) overexpressing FDH1 exhibited greater resistance to Pseudomonas syringae pv tomato in a salicylic acid-dependent manner. Arabidopsis transfer DNA insertion mutant analysis indicated that AtFDH1 expression is required for basal defense and resistance gene-mediated resistance to P. syringae pv tomato infection. Taken together, these data suggest that FDH1 has an important role in HR-like cell death and defense responses to bacterial pathogens.
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Affiliation(s)
- Du Seok Choi
- Laboratory of Molecular Plant Pathology, College of Life Sciences and Biotechnology, Korea University, Seoul 136-713, Republic of Korea
| | - Nak Hyun Kim
- Laboratory of Molecular Plant Pathology, College of Life Sciences and Biotechnology, Korea University, Seoul 136-713, Republic of Korea
| | - Byung Kook Hwang
- Laboratory of Molecular Plant Pathology, College of Life Sciences and Biotechnology, Korea University, Seoul 136-713, Republic of Korea
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106
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Kessens R, Ashfield T, Kim SH, Innes RW. Determining the GmRIN4 requirements of the soybean disease resistance proteins Rpg1b and Rpg1r using a nicotiana glutinosa-based agroinfiltration system. PLoS One 2014; 9:e108159. [PMID: 25244054 PMCID: PMC4171518 DOI: 10.1371/journal.pone.0108159] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2014] [Accepted: 08/25/2014] [Indexed: 12/13/2022] Open
Abstract
Rpg1b and Rpg1r are soybean disease resistance (R) genes responsible for conferring resistance to Pseudomonas syringae strains expressing the effectors AvrB and AvrRpm1, respectively. The study of these cloned genes would be greatly facilitated by the availability of a suitable transient expression system. The commonly used Niciotiana benthamiana-based system is not suitable for studying Rpg1b and Rpg1r function, however, because expression of AvrB or AvrRpm1 alone induces a hypersensitive response (HR), indicating that N. benthamiana contains endogenous R genes that recognize these effectors. To identify a suitable alternative host for transient expression assays, we screened 13 species of Nicotiana along with 11 accessions of N. tabacum for lack of response to transient expression of AvrB and AvrRpm1. We found that N. glutinosa did not respond to either effector and was readily transformable as determined by transient expression of β-glucuronidase. Using this system, we determined that Rpg1b-mediated HR in N. glutinosa required co-expression of avrB and a soybean ortholog of the Arabidopsis RIN4 gene. All four soybean RIN4 orthologs tested worked in the assay. In contrast, Rpg1r did not require co-expression of a soybean RIN4 ortholog to recognize AvrRpm1, but recognition was suppressed by co-expression with AvrRpt2. These observations suggest that an endogenous RIN4 gene in N. glutinosa can substitute for the soybean RIN4 ortholog in the recognition of AvrRpm1 by Rpg1r.
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Affiliation(s)
- Ryan Kessens
- Department of Biology, Indiana University, Bloomington, Indiana, United States of America
| | - Tom Ashfield
- Department of Biology, Indiana University, Bloomington, Indiana, United States of America
| | - Sang Hee Kim
- Department of Biology, Indiana University, Bloomington, Indiana, United States of America
| | - Roger W. Innes
- Department of Biology, Indiana University, Bloomington, Indiana, United States of America
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107
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Césari S, Kanzaki H, Fujiwara T, Bernoux M, Chalvon V, Kawano Y, Shimamoto K, Dodds P, Terauchi R, Kroj T. The NB-LRR proteins RGA4 and RGA5 interact functionally and physically to confer disease resistance. EMBO J 2014; 33:1941-59. [PMID: 25024433 PMCID: PMC4195788 DOI: 10.15252/embj.201487923] [Citation(s) in RCA: 234] [Impact Index Per Article: 23.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2014] [Revised: 05/20/2014] [Accepted: 06/05/2014] [Indexed: 12/27/2022] Open
Abstract
Plant resistance proteins of the class of nucleotide-binding and leucine-rich repeat domain proteins (NB-LRRs) are immune sensors which recognize pathogen-derived molecules termed avirulence (AVR) proteins. We show that RGA4 and RGA5, two NB-LRRs from rice, interact functionally and physically to mediate resistance to the fungal pathogen Magnaporthe oryzae and accomplish different functions in AVR recognition. RGA4 triggers an AVR-independent cell death that is repressed in the presence of RGA5 in both rice protoplasts and Nicotiana benthamiana. Upon recognition of the pathogen effector AVR-Pia by direct binding to RGA5, repression is relieved and cell death occurs. RGA4 and RGA5 form homo- and hetero-complexes and interact through their coiled-coil domains. Localization studies in rice protoplast suggest that RGA4 and RGA5 localize to the cytosol. Upon recognition of AVR-Pia, neither RGA4 nor RGA5 is re-localized to the nucleus. These results establish a model for the interaction of hetero-pairs of NB-LRRs in plants: RGA4 mediates cell death activation, while RGA5 acts as a repressor of RGA4 and as an AVR receptor.
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Affiliation(s)
- Stella Césari
- INRA UMR BGPI, Montpellier, France CIRAD UMR BGPI, Montpellier, France CSIRO Plant Industry, Canberra, ACT, Australia
| | | | - Tadashi Fujiwara
- Laboratory of Plant Molecular Genetics, Nara Institute of Science and Technology, Takayama Ikoma, Japan
| | | | - Véronique Chalvon
- INRA UMR BGPI, Montpellier, France CIRAD UMR BGPI, Montpellier, France
| | - Yoji Kawano
- Laboratory of Plant Molecular Genetics, Nara Institute of Science and Technology, Takayama Ikoma, Japan
| | - Ko Shimamoto
- Laboratory of Plant Molecular Genetics, Nara Institute of Science and Technology, Takayama Ikoma, Japan
| | - Peter Dodds
- CSIRO Plant Industry, Canberra, ACT, Australia
| | | | - Thomas Kroj
- INRA UMR BGPI, Montpellier, France CIRAD UMR BGPI, Montpellier, France
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108
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Buscaill P, Rivas S. Transcriptional control of plant defence responses. CURRENT OPINION IN PLANT BIOLOGY 2014; 20:35-46. [PMID: 24840291 DOI: 10.1016/j.pbi.2014.04.004] [Citation(s) in RCA: 140] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2014] [Revised: 04/17/2014] [Accepted: 04/24/2014] [Indexed: 05/22/2023]
Abstract
Mounting of efficient plant defence responses depends on the ability to trigger a rapid defence reaction after recognition of the invading microbe. Activation of plant resistance is achieved by modulation of the activity of multiple transcriptional regulators, both DNA-binding transcription factors and their regulatory proteins, that are able to reprogram transcription in the plant cell towards the activation of defence signalling. Here we provide an overview of recent developments on the transcriptional control of plant defence responses and discuss defence-related hormone signalling, the role of WRKY transcription factors during the regulation of plant responses to pathogens, nuclear functions of plant immune receptor proteins, as well as varied ways by which microbial effectors subvert plant transcriptional reprogramming to promote disease.
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Affiliation(s)
- Pierre Buscaill
- INRA, Laboratoire des Interactions Plantes-Microorganismes (LIPM), UMR441, F-31326 Castanet-Tolosan, France
| | - Susana Rivas
- CNRS, Laboratoire des Interactions Plantes-Microorganismes (LIPM), UMR2594, F-31326 Castanet-Tolosan, France.
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109
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Zhai C, Zhang Y, Yao N, Lin F, Liu Z, Dong Z, Wang L, Pan Q. Function and interaction of the coupled genes responsible for Pik-h encoded rice blast resistance. PLoS One 2014; 9:e98067. [PMID: 24896089 PMCID: PMC4045721 DOI: 10.1371/journal.pone.0098067] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2014] [Accepted: 04/25/2014] [Indexed: 12/20/2022] Open
Abstract
Pik-h, an allele of Pik, confers resistance against the rice blast pathogen Magnaporthe oryzae. Its positional cloning has shown that it comprises a pair of NBS-LRR genes, Pikh-1 and Pikh-2. While Pikh-1 appears to be constitutively transcribed, the transcript abundance of Pikh-2 responds to pathogen challenge. The Pikh-1 CC (coiled coil) domain interacts directly with both AvrPik-h and Pikh-2. Transient expression assays demonstrated that Pikh-2 mediates the initiation of the host defence response. Nucleocytoplasmic partitioning of both Pikh-1 and Pikh-2 is required for their functionalities. In a proposed mechanistic model of Pik-h resistance, it is suggested that Pikh-1 acts as an adaptor between AvrPik-h and Pikh-2, while Pikh-2 transduces the signal to trigger Pik-h-specific resistance.
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Affiliation(s)
- Chun Zhai
- National Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, South China Agricultural University, Guangzhou, China
- Guangdong Provincial Key Laboratory for Microbe Signals and Crop Disease Control, South China Agricultural University, Guangzhou, China
| | - Yu Zhang
- National Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, South China Agricultural University, Guangzhou, China
- Guangdong Provincial Key Laboratory for Microbe Signals and Crop Disease Control, South China Agricultural University, Guangzhou, China
| | - Nan Yao
- National Key Laboratory of Biocontrol, College of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Fei Lin
- National Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, South China Agricultural University, Guangzhou, China
- Guangdong Provincial Key Laboratory for Microbe Signals and Crop Disease Control, South China Agricultural University, Guangzhou, China
| | - Zhe Liu
- National Key Laboratory of Biocontrol, College of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Zhongqiu Dong
- National Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, South China Agricultural University, Guangzhou, China
- Guangdong Provincial Key Laboratory for Microbe Signals and Crop Disease Control, South China Agricultural University, Guangzhou, China
| | - Ling Wang
- National Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, South China Agricultural University, Guangzhou, China
- Guangdong Provincial Key Laboratory for Microbe Signals and Crop Disease Control, South China Agricultural University, Guangzhou, China
| | - Qinghua Pan
- National Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, South China Agricultural University, Guangzhou, China
- Guangdong Provincial Key Laboratory for Microbe Signals and Crop Disease Control, South China Agricultural University, Guangzhou, China
- * E-mail:
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110
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Kawano Y, Fujiwara T, Yao A, Housen Y, Hayashi K, Shimamoto K. Palmitoylation-dependent membrane localization of the rice resistance protein pit is critical for the activation of the small GTPase OsRac1. J Biol Chem 2014; 289:19079-88. [PMID: 24841201 DOI: 10.1074/jbc.m114.569756] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Nucleotide binding domain and leucine-rich repeat (NLR)-containing family proteins function as intracellular immune sensors in both plants and animals. In plants, the downstream components activated by NLR family proteins and the immune response mechanisms induced by these downstream molecules are largely unknown. We have previously found that the small GTPase OsRac1, which acts as a molecular switch in rice immunity, is activated by Pit, an NLR-type resistance (R) protein to rice blast fungus, and this activation plays critical roles in Pit-mediated immunity. However, the sites and mechanisms of activation of Pit in vivo remain unknown. To clarify the mechanisms involved in the localization of Pit, we searched for consensus sequences in Pit that specify membrane localization and found a pair of potential palmitoylation sites in the N-terminal coiled-coil region. Although wild-type Pit was localized mainly to the plasma membrane, this membrane localization was compromised in a palmitoylation-deficient mutant of Pit. The palmitoylation-deficient Pit displayed significantly lower affinity for OsRac1 on the plasma membrane, thereby resulting in failures of the Pit-mediated cell death, the production of reactive oxygen species, and disease resistance to rice blast fungus. These results indicate that palmitoylation-dependent membrane localization of Pit is required for the interaction with and the activation of OsRac1 and that OsRac1 activation by Pit is vital for Pit-mediated disease resistance to rice blast fungus.
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Affiliation(s)
- Yoji Kawano
- From the Laboratory of Plant Molecular Genetics, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara 630-0101, Japan and
| | - Tadashi Fujiwara
- From the Laboratory of Plant Molecular Genetics, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara 630-0101, Japan and
| | - Ai Yao
- From the Laboratory of Plant Molecular Genetics, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara 630-0101, Japan and
| | - Yusuke Housen
- From the Laboratory of Plant Molecular Genetics, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara 630-0101, Japan and
| | - Keiko Hayashi
- National Agricultural Research Center, National Agriculture and Food Research Organization, 3-1-1 Kannondai, Tsukuba, Ibaraki 305-8666, Japan
| | - Ko Shimamoto
- From the Laboratory of Plant Molecular Genetics, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara 630-0101, Japan and
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111
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Cheng C, Gao X, Feng B, Sheen J, Shan L, He P. Plant immune response to pathogens differs with changing temperatures. Nat Commun 2014; 4:2530. [PMID: 24067909 DOI: 10.1038/ncomms3530] [Citation(s) in RCA: 127] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2013] [Accepted: 09/02/2013] [Indexed: 01/19/2023] Open
Abstract
Temperature fluctuation is a key determinant for microbial invasion and host evasion. In contrast to mammals that maintain constant body temperature, plant temperature oscillates on a daily basis. It remains elusive how plants operate inducible defenses in response to temperature fluctuation. Here we report that ambient temperature changes lead to pronounced shifts of the following two distinct plant immune responses: pattern-triggered immunity (PTI) and effector-triggered immunity (ETI). Plants preferentially activate ETI signaling at relatively low temperatures (10-23 °C), whereas they switch to PTI signaling at moderately elevated temperatures (23-32 °C). The Arabidopsis arp6 and hta9hta11 mutants, phenocopying plants grown at elevated temperatures, exhibit enhanced PTI and yet reduced ETI responses. As the secretion of bacterial effectors favours low temperatures, whereas bacteria multiply vigorously at elevated temperatures accompanied with increased microbe-associated molecular pattern production, our findings suggest that temperature oscillation might have driven dynamic co-evolution of distinct plant immune signaling responding to pathogen physiological changes.
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Affiliation(s)
- Cheng Cheng
- 1] Department of Biochemistry and Biophysics, Institute for Plant Genomics and Biotechnology, Texas A&M University, College Station, Texas 77843, USA [2]
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112
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Gao X, Cox KL, He P. Functions of Calcium-Dependent Protein Kinases in Plant Innate Immunity. PLANTS 2014; 3:160-76. [PMID: 27135498 PMCID: PMC4844305 DOI: 10.3390/plants3010160] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/03/2013] [Revised: 01/20/2014] [Accepted: 02/06/2014] [Indexed: 01/27/2023]
Abstract
An increase of cytosolic Ca2+ is generated by diverse physiological stimuli and stresses, including pathogen attack. Plants have evolved two branches of the immune system to defend against pathogen infections. The primary innate immune response is triggered by the detection of evolutionarily conserved pathogen-associated molecular pattern (PAMP), which is called PAMP-triggered immunity (PTI). The second branch of plant innate immunity is triggered by the recognition of specific pathogen effector proteins and known as effector-triggered immunity (ETI). Calcium (Ca2+) signaling is essential in both plant PTI and ETI responses. Calcium-dependent protein kinases (CDPKs) have emerged as important Ca2+ sensor proteins in transducing differential Ca2+ signatures, triggered by PAMPs or effectors and activating complex downstream responses. CDPKs directly transmit calcium signals by calcium binding to the elongation factor (EF)-hand domain at the C-terminus and substrate phosphorylation by the catalytic kinase domain at the N-terminus. Emerging evidence suggests that specific and overlapping CDPKs phosphorylate distinct substrates in PTI and ETI to regulate diverse plant immune responses, including production of reactive oxygen species, transcriptional reprogramming of immune genes, and the hypersensitive response.
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Affiliation(s)
- Xiquan Gao
- State Key Laboratory of Crop Genetics and Germplasm Enhancement, College of Agriculture, Nanjing Agricultural University, Nanjing 210095, China.
| | - Kevin L Cox
- Department of Plant Pathology and Microbiology, Institute for Plant Genomics and Biotechnology, Texas A&M University, College Station, TX 77843, USA
| | - Ping He
- Department of Biochemistry and Biophysics, Institute for Plant Genomics and Biotechnology, Texas A&M University, College Station, TX 77843, USA.
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113
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Stirnweis D, Milani SD, Jordan T, Keller B, Brunner S. Substitutions of two amino acids in the nucleotide-binding site domain of a resistance protein enhance the hypersensitive response and enlarge the PM3F resistance spectrum in wheat. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2014; 27:265-76. [PMID: 24329172 DOI: 10.1094/mpmi-10-13-0297-fi] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Proteins with nucleotide-binding site (NBS) and leucine-rich repeat (LRR) domains are major components of the plant immune system. They usually mediate resistance against a subgroup of races of a specific pathogen. For the allelic series of the wheat powdery mildew resistance gene Pm3, alleles with a broad and a narrow resistance spectrum have been described. Here, we show that a broad Pm3 spectrum range correlates with a fast and intense hypersensitive response (HR) in a Nicotiana transient-expression system and this activity can be attributed to two particular amino acids in the ARC2 subdomain of the NBS. The combined substitution of these amino acids in narrow-spectrum PM3 proteins enhances their capacity to induce an HR in Nicotiana benthamiana, and we demonstrate that these substitutions also enlarge the resistance spectrum of the Pm3f allele in wheat. Finally, using Bph14, we show that the region carrying the relevant amino acids also plays a role in the HR regulation of another coiled-coil NBS-LRR resistance protein. These results highlight the importance of an optimized NBS-'molecular switch' for the conversion of initial pathogen perception by the LRR into resistance-protein activation, and we describe a possible approach to extend the effectiveness of resistance genes via minimal targeted modifications in the NBS domain.
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114
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Teh OK, Hofius D. Membrane trafficking and autophagy in pathogen-triggered cell death and immunity. JOURNAL OF EXPERIMENTAL BOTANY 2014; 65:1297-312. [PMID: 24420567 DOI: 10.1093/jxb/ert441] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Plants respond to pathogen attack with dynamic rearrangements of the endomembrane system and rapid redirection of membrane traffic to facilitate effective host defence. Mounting evidence indicates the involvement of endocytic, secretory, and vacuolar trafficking pathways in immune receptor activation, signal transduction, and execution of multiple defence responses including programmed cell death (PCD). Autophagy is a conserved intracellular trafficking and degradation process and has been implicated in basal immunity as well as in some forms of immune receptor-mediated vacuolar cell death. However, the regulatory interplay of autophagy and other membrane trafficking pathways in PCD and defence responses remains obscure. This review therefore highlights recent advances in the understanding of autophagic and membrane trafficking during plant immunity, and discusses emerging molecular links and functional interconnections.
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Affiliation(s)
- Ooi-Kock Teh
- Department of Plant Biology and Forest Genetics, Uppsala BioCenter, Swedish University of Agricultural Sciences (SLU) and Linnean Center of Plant Biology, SE-75007 Uppsala, Sweden
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115
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Huang YY, Shi Y, Lei Y, Li Y, Fan J, Xu YJ, Ma XF, Zhao JQ, Xiao S, Wang WM. Functional identification of multiple nucleocytoplasmic trafficking signals in the broad-spectrum resistance protein RPW8.2. PLANTA 2014; 239:455-68. [PMID: 24218059 DOI: 10.1007/s00425-013-1994-x] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2013] [Accepted: 10/30/2013] [Indexed: 06/02/2023]
Abstract
Nuclear localization signals (NLSs) and nuclear export signals (NESs) are important intramolecular regulatory elements for protein nucleocytoplasmic trafficking. This regulation confers spatial specificity to signal initiation and transduction in eukaryotic cells and thus is fundamental to the viability of all eukaryotic organisms. Here, we developed a simple and rapid method in which activity of putative NLSs or NESs was reported by subcellular localization of two tandem fluorescent proteins in fusion with the respective NLSs or NESs after agroinfiltration-mediated transient expression in leaves of Nicotiana benthamiana (Nb). We further demonstrated that the predicted NES from amino acid residue (aa) 9 to 22 and the NLS from aa91 to 101 in the broad-spectrum disease resistance protein RPW8.2 possess nuclear export and import activity, respectively. Additionally, by testing overlapping fragments covering the full length of RPW8.2, we identified another NLS from aa65 to 74 with strong nuclear import activity and two tandem non-canonical NESs in the C-terminus with strong nuclear export activity. Taken together, our results demonstrated the utility of a simple method to evaluate potential NLSs and NESs in plant cells and suggested that RPW8.2 may be subject to opposing nucleocytoplasmic trafficking forces for its subcellular localization and functional execution.
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Affiliation(s)
- Yan-Yan Huang
- Rice Research Institute, Sichuan Agricultural University, Chengdu, 611130, China
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116
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Qi D, Innes RW. Recent Advances in Plant NLR Structure, Function, Localization, and Signaling. Front Immunol 2013; 4:348. [PMID: 24155748 PMCID: PMC3801107 DOI: 10.3389/fimmu.2013.00348] [Citation(s) in RCA: 107] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2013] [Accepted: 10/09/2013] [Indexed: 12/14/2022] Open
Abstract
Nucleotide-binding domain leucine-rich repeat (NLR) proteins play a central role in the innate immune systems of plants and vertebrates. In plants, NLR proteins function as intracellular receptors that detect pathogen effector proteins directly, or indirectly by recognizing effector-induced modifications to other host proteins. NLR activation triggers a suite of defense responses associated with programed cell death (PCD). The molecular mechanisms underlying NLR activation, and how activation is translated into defense responses, have been particularly challenging to elucidate in plants. Recent reports, however, are beginning to shed some light. It is becoming clear that plant NLR proteins are targeted to diverse sub-cellular locations, likely depending on the locations where the effectors are detected. These reports also indicate that some NLRs re-localize following effector detection, while others do not, and such relocalization may reflect differences in signaling pathways. There have also been recent advances in understanding the structure of plant NLR proteins, with crystal structures now available for the N-terminal domains of two well-studied NLRs, a coiled-coil (CC) domain and a Toll-interleukin Receptor (TIR). Significant improvements in molecular modeling have enabled more informed structure-function studies, illuminating roles of intra- and inter-molecular interactions in NLR activation regulation. Several independent studies also suggest that intracellular trafficking is involved in NLR-mediated resistance. Lastly, progress is being made on identifying transcriptional regulatory complexes activated by NLRs. Current models for how plant NLR proteins are activated and how they induce defenses are discussed, with an emphasis on what remains to be determined.
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Affiliation(s)
- Dong Qi
- Department of Biology, Indiana University , Bloomington, IN , USA
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117
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Abstract
Over the past decade, considerable advances have been made in understanding the molecular mechanisms that underpin the arms race between plant pathogens and their hosts. Alongside genomic, bioinformatic, proteomic, biochemical and cell biological analyses of plant-pathogen interactions, three-dimensional structural studies of virulence proteins deployed by pathogens to promote infection, in some cases complexed with their plant cell targets, have uncovered key insights into the functions of these molecules. Structural information on plant immune receptors, which regulate the response to pathogen attack, is also starting to emerge. Structural studies of bacterial plant pathogen-host systems have been leading the way, but studies of filamentous plant pathogens are gathering pace. In this Review, we summarize the key developments in the structural biology of plant pathogen-host interactions.
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118
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Jacob F, Vernaldi S, Maekawa T. Evolution and Conservation of Plant NLR Functions. Front Immunol 2013; 4:297. [PMID: 24093022 PMCID: PMC3782705 DOI: 10.3389/fimmu.2013.00297] [Citation(s) in RCA: 182] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2013] [Accepted: 09/09/2013] [Indexed: 12/21/2022] Open
Abstract
In plants and animals, nucleotide-binding domain and leucine-rich repeats (NLR)-containing proteins play pivotal roles in innate immunity. Despite their similar biological functions and protein architecture, comparative genome-wide analyses of NLRs and genes encoding NLR-like proteins suggest that plant and animal NLRs have independently arisen in evolution. Furthermore, the demonstration of interfamily transfer of plant NLR functions from their original species to phylogenetically distant species implies evolutionary conservation of the underlying immune principle across plant taxonomy. In this review we discuss plant NLR evolution and summarize recent insights into plant NLR-signaling mechanisms, which might constitute evolutionarily conserved NLR-mediated immune mechanisms.
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Affiliation(s)
- Florence Jacob
- Department of Plant-Microbe Interactions, Max Planck Institute for Plant Breeding Research , Cologne , Germany ; Unité de Recherche en Génomique Végétale, Institut National de la Recherche Agronomique, Centre National de la Recherche Scientifique, Université Evry Val d'Essone , Evry , France
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119
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Bhattacharjee S, Garner CM, Gassmann W. New clues in the nucleus: transcriptional reprogramming in effector-triggered immunity. FRONTIERS IN PLANT SCIENCE 2013; 4:364. [PMID: 24062762 PMCID: PMC3772313 DOI: 10.3389/fpls.2013.00364] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2013] [Accepted: 08/27/2013] [Indexed: 05/05/2023]
Abstract
The robustness of plant effector-triggered immunity is correlated with massive alterations of the host transcriptome. Yet the molecular mechanisms that cause and underlie this reprogramming remain obscure. Here we will review recent advances in deciphering nuclear functions of plant immune receptors and of associated proteins. Important open questions remain, such as the identities of the primary transcription factors involved in control of effector-triggered immune responses, and indeed whether this can be generalized or whether particular effector-resistance protein interactions impinge on distinct sectors in the transcriptional response web. Multiple lines of evidence have implicated WRKY transcription factors at the core of responses to microbe-associated molecular patterns and in intersections with effector-triggered immunity. Recent findings from yeast two-hybrid studies suggest that members of the TCP transcription factor family are targets of several effectors from diverse pathogens. Additional transcription factor families that are directly or indirectly involved in effector-triggered immunity are likely to be identified.
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Affiliation(s)
- Saikat Bhattacharjee
- Division of Plant Sciences, University of MissouriColumbia, MO, USA
- Christopher S. Bond Life Sciences Center and Interdisciplinary Plant Group, University of MissouriColumbia, MO, USA
- *Correspondence: Saikat Bhattacharjee, Division of Plant Sciences, University of Missouri, 314, Christopher S. Bond Life Sciences Center, Columbia, MO 65211, USA e-mail:
| | - Christopher M. Garner
- Christopher S. Bond Life Sciences Center and Interdisciplinary Plant Group, University of MissouriColumbia, MO, USA
- Division of Biological Sciences, University of MissouriColumbia, MO, USA
| | - Walter Gassmann
- Division of Plant Sciences, University of MissouriColumbia, MO, USA
- Christopher S. Bond Life Sciences Center and Interdisciplinary Plant Group, University of MissouriColumbia, MO, USA
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120
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Henry E, Yadeta KA, Coaker G. Recognition of bacterial plant pathogens: local, systemic and transgenerational immunity. THE NEW PHYTOLOGIST 2013; 199:908-15. [PMID: 23909802 PMCID: PMC3740753 DOI: 10.1111/nph.12214] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2012] [Accepted: 02/05/2013] [Indexed: 05/19/2023]
Abstract
Bacterial pathogens can cause multiple plant diseases and plants rely on their innate immune system to recognize and actively respond to these microbes. The plant innate immune system comprises extracellular pattern recognition receptors that recognize conserved microbial patterns and intracellular nucleotide binding leucine-rich repeat (NLR) proteins that recognize specific bacterial effectors delivered into host cells. Plants lack the adaptive immune branch present in animals, but still afford flexibility to pathogen attack through systemic and transgenerational resistance. Here, we focus on current research in plant immune responses against bacterial pathogens. Recent studies shed light onto the activation and inactivation of pattern recognition receptors and systemic acquired resistance. New research has also uncovered additional layers of complexity surrounding NLR immune receptor activation, cooperation and sub-cellular localizations. Taken together, these recent advances bring us closer to understanding the web of molecular interactions responsible for coordinating defense responses and ultimately resistance.
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Affiliation(s)
- Elizabeth Henry
- Department of Plant Pathology, University of California at Davis, Davis, CA, USA
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121
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Afzal AJ, Kim JH, Mackey D. The role of NOI-domain containing proteins in plant immune signaling. BMC Genomics 2013; 14:327. [PMID: 23672422 PMCID: PMC3661340 DOI: 10.1186/1471-2164-14-327] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2012] [Accepted: 03/26/2013] [Indexed: 02/04/2023] Open
Abstract
Here we present an overview of our existing knowledge on the function of RIN4 as a regulator of plant defense and as a guardee of multiple plant R-proteins. Domain analysis of RIN4 reveals two NOI domains. The NOI domain was originally identified in a screen for nitrate induced genes. The domain is comprised of approximately 30 amino acids and contains 2 conserved motifs (PXFGXW and Y/FTXXF). The NOI gene family contains members exclusively from the plant lineage as far back as moss. In addition to the conserved NOI domain, members within the family also contain conserved C-terminal cysteine residue(s) which are sites for acylation and membrane tethering. Other than these two characteristic features, the sequence of the family of NOI-containing proteins is diverse and, with the exception of RIN4, their functions are not known. Recently published interactome data showing interactions between RIN4 and components of the exocyst complex prompt us to raise the hypothesis that RIN4 might be involved in defense associated vesicle trafficking.
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Affiliation(s)
- Ahmed J Afzal
- Department of Horticulture and Crop Science, The Ohio State University, Columbus, OH, USA.
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122
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Roberts M, Tang S, Stallmann A, Dangl JL, Bonardi V. Genetic requirements for signaling from an autoactive plant NB-LRR intracellular innate immune receptor. PLoS Genet 2013; 9:e1003465. [PMID: 23633962 PMCID: PMC3636237 DOI: 10.1371/journal.pgen.1003465] [Citation(s) in RCA: 83] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2012] [Accepted: 03/05/2013] [Indexed: 12/27/2022] Open
Abstract
Plants react to pathogen attack via recognition of, and response to, pathogen-specific molecules at the cell surface and inside the cell. Pathogen effectors (virulence factors) are monitored by intracellular nucleotide-binding leucine-rich repeat (NB-LRR) sensor proteins in plants and mammals. Here, we study the genetic requirements for defense responses of an autoactive mutant of ADR1-L2, an Arabidopsis coiled-coil (CC)-NB-LRR protein. ADR1-L2 functions upstream of salicylic acid (SA) accumulation in several defense contexts, and it can act in this context as a “helper” to transduce specific microbial activation signals from “sensor” NB-LRRs. This helper activity does not require an intact P-loop. ADR1-L2 and another of two closely related members of this small NB-LRR family are also required for propagation of unregulated runaway cell death (rcd) in an lsd1 mutant. We demonstrate here that, in this particular context, ADR1-L2 function is P-loop dependent. We generated an autoactive missense mutation, ADR1-L2D484V, in a small homology motif termed MHD. Expression of ADR1-L2D848V leads to dwarfed plants that exhibit increased disease resistance and constitutively high SA levels. The morphological phenotype also requires an intact P-loop, suggesting that these ADR1-L2D484V phenotypes reflect canonical activation of this NB-LRR protein. We used ADR1-L2D484V to define genetic requirements for signaling. Signaling from ADR1-L2D484V does not require NADPH oxidase and is negatively regulated by EDS1 and AtMC1. Transcriptional regulation of ADR1-L2D484V is correlated with its phenotypic outputs; these outputs are both SA–dependent and –independent. The genetic requirements for ADR1-L2D484V activity resemble those that regulate an SA–gradient-dependent signal amplification of defense and cell death signaling initially observed in the absence of LSD1. Importantly, ADR1-L2D484V autoactivation signaling is controlled by both EDS1 and SA in separable, but linked pathways. These data allows us to propose a genetic model that provides insight into an SA–dependent feedback regulation loop, which, surprisingly, includes ADR1-L2. Plants possess an active, inducible disease resistance system, and induction of these responses depends in part on plant resistance proteins. Present understanding of these resistance proteins likens them to molecular switches that bind nucleotides to activate disease resistance responses. Previously it was shown that Activated Disease Resistance 1-like 2 (ADR1-L2), a plant disease resistance protein, is important in the immune response, but can function in the contexts analysed independently of what is currently considered the canonical nucleotide switch activation. Here, we show that, in addition to these previously reported functions, ADR1-L2 also works as a typical, activated disease resistance protein. We use an autoactive mutant form of the protein and show that it promotes disease resistance. We find that ADR1-L2 works in an EDS1-dependent feedback loop with salicylic acid, a hormone known to be essential for plant disease resistance. This work allows us to broaden the understanding of how plant disease resistance proteins function to generate defense against pathogens.
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Affiliation(s)
- Melinda Roberts
- Department of Biology, University of North Carolina, Chapel Hill, North Carolina, United States of America
| | - Saijun Tang
- College of Biological Sciences, China Agricultural University, Beijing, China
| | - Anna Stallmann
- Department of Biology, University of North Carolina, Chapel Hill, North Carolina, United States of America
| | - Jeffery L. Dangl
- Department of Biology, University of North Carolina, Chapel Hill, North Carolina, United States of America
- Howard Hughes Medical Institute, University of North Carolina, Chapel Hill, North Carolina, United States of America
- Curriculum in Genetics and Molecular Biology, University of North Carolina, Chapel Hill, North Carolina, United States of America
- Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, North Carolina, United States of America
- Carolina Center for Genome Sciences, University of North Carolina, Chapel Hill, North Carolina, United States of America
- * E-mail:
| | - Vera Bonardi
- Department of Biology, University of North Carolina, Chapel Hill, North Carolina, United States of America
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123
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Marone D, Russo MA, Laidò G, De Leonardis AM, Mastrangelo AM. Plant nucleotide binding site-leucine-rich repeat (NBS-LRR) genes: active guardians in host defense responses. Int J Mol Sci 2013; 14:7302-26. [PMID: 23549266 PMCID: PMC3645687 DOI: 10.3390/ijms14047302] [Citation(s) in RCA: 173] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2013] [Revised: 03/21/2013] [Accepted: 03/26/2013] [Indexed: 11/16/2022] Open
Abstract
The most represented group of resistance genes are those of the nucleotide binding site-leucine-rich repeat (NBS-LRR) class. These genes are very numerous in the plant genome, and they often occur in clusters at specific loci following gene duplication and amplification events. To date, hundreds of resistance genes and relatively few quantitative trait loci for plant resistance to pathogens have been mapped in different species, with some also cloned. When these NBS-LRR genes have been physically or genetically mapped, many cases have shown co-localization between resistance loci and NBS-LRR genes. This has allowed the identification of candidate genes for resistance, and the development of molecular markers linked to R genes. This review is focused on recent genomics studies that have described the abundance, distribution and evolution of NBS-LRR genes in plant genomes. Furthermore, in terms of their expression, NBS-LRR genes are under fine regulation by cis- and trans-acting elements. Recent findings have provided insights into the roles of alternative splicing, the ubiquitin/ proteasome system, and miRNAs and secondary siRNAs in the regulation of NBS-LRR gene expression at the post-transcriptional, post-translational and epigenetic levels. The possibility to use this knowledge for genetic improvement of plant resistance to pathogens is discussed.
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Affiliation(s)
- Daniela Marone
- Consiglio per la Ricerca e la Sperimentazione in Agricoltura, Agricultural Research Council-Cereal Research Centre (CRA-CER), SS 16 km 675, 71122 Foggia, Italy.
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124
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Gao X, He P. Nuclear dynamics of Arabidopsis calcium-dependent protein kinases in effector-triggered immunity. PLANT SIGNALING & BEHAVIOR 2013; 8:e23868. [PMID: 23425856 PMCID: PMC3956488 DOI: 10.4161/psb.23868] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2013] [Accepted: 02/02/2013] [Indexed: 05/22/2023]
Abstract
Plants have evolved sophisticated innate immune systems to protect themselves from potential microbial invasions. Recognition of pathogen-derived virulence effector proteins is mediated by plant resistance (R) proteins and elicits potent defense responses, collectively termed as effector-triggered immunity (ETI). It has long been known that ETI is often accompanied with the increase of cytosolic Ca(2+) levels. We recently identified six closely related calcium-dependent protein kinases (CPKs) in Arabidopsis that orchestrate bifurcate ETI signaling via distinct substrate specificity and subcellular dynamics. In particular, the activation of CPK4, 5, 6 and 11 phosphorylates a specific subgroup of WRKY transcription factors to regulate transcriptional reprogramming crucial for restriction of pathogen growth. Upon ETI activation, a significant portion of CPK5 re-localizes to nucleus where it interacts and phosphorylates WRKY8, 28 and 48. Mass spectrometry analysis identified several conserved residues, including T247/T248 in WRKY48 and T199 in WRKY28 as the phosphorylation sites by CPKs. Here we reported that mutation of T198/T199 into alanine (TT198AA) in WRKY28 completely abolished its phosphorylation by CPK4 and 11. The importance of nuclear localization of CPK5 was further demonstrated by that CPK5 fused with nuclear export signal abolished its synergistic effect with WRKY8, 28 and 48 on the activation of defense gene. In contrast, effector AvrRpt2 likely functions in the cytoplasm to activate the transcriptional reprogramming of defense genes, consistent with the plasma membrane localization of its RPS2 receptor. Our data established WRKYs as bona fide substrates of CPKs and provided a framework for the study of CPK-WRKY cascade in diverse biological processes. Our results also demonstrated that the nuclear localization and subcellular dynamics of CPKs are essential to relay distinct ETI signaling events.
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125
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Bifurcation of Arabidopsis NLR immune signaling via Ca²⁺-dependent protein kinases. PLoS Pathog 2013; 9:e1003127. [PMID: 23382673 PMCID: PMC3561149 DOI: 10.1371/journal.ppat.1003127] [Citation(s) in RCA: 212] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2012] [Accepted: 11/28/2012] [Indexed: 11/30/2022] Open
Abstract
Nucleotide-binding domain leucine-rich repeat (NLR) protein complexes sense infections and trigger robust immune responses in plants and humans. Activation of plant NLR resistance (R) proteins by pathogen effectors launches convergent immune responses, including programmed cell death (PCD), reactive oxygen species (ROS) production and transcriptional reprogramming with elusive mechanisms. Functional genomic and biochemical genetic screens identified six closely related Arabidopsis Ca2+-dependent protein kinases (CPKs) in mediating bifurcate immune responses activated by NLR proteins, RPS2 and RPM1. The dynamics of differential CPK1/2 activation by pathogen effectors controls the onset of cell death. Sustained CPK4/5/6/11 activation directly phosphorylates a specific subgroup of WRKY transcription factors, WRKY8/28/48, to synergistically regulate transcriptional reprogramming crucial for NLR-dependent restriction of pathogen growth, whereas CPK1/2/4/11 phosphorylate plasma membrane-resident NADPH oxidases for ROS production. Our studies delineate bifurcation of complex signaling mechanisms downstream of NLR immune sensors mediated by the myriad action of CPKs with distinct substrate specificity and subcellular dynamics. Distinguishing self from non-self is the fundamental principle of immunity. Nucleotide-binding leucine-rich repeat (NLR) proteins were first identified in plants as disease resistance proteins and were recently found to play essential roles in mammalian innate immunity and inflammation. NLR protein complexes sense intracellular pathogenic effectors in plants and microbial patterns and danger signals in humans, but the signaling mechanisms upon NLR activation remain elusive. Using the Arabidopsis-Pseudomonas interaction as a model system, we discovered the molecular link between NLR immune sensors and the convergent immune responses triggered by distinct pathogen effectors. Integrated functional genomic and biochemical genetic screens identified six closely related Ca2+-dependent protein kinases (CPKs) that orchestrate bifurcate NLR immune signaling via distinct substrate specificity and subcellular dynamics. The CPK1/2 regulate the onset of programmed cell death; CPK4/5/6/11 phosphorylate specific WRKY transcription factors to regulate immune gene expression crucial for NLR-dependent restriction of pathogen growth, whereas CPK1/2/4/11 phosphorylate NADPH oxidases for the production of reactive oxygen species. Our studies decode the complex signaling mechanisms via the myriad action of CPKs downstream of NLR immune sensors.
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126
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Ma L, Cornelissen BJC, Takken FLW. A nuclear localization for Avr2 from Fusarium oxysporum is required to activate the tomato resistance protein I-2. FRONTIERS IN PLANT SCIENCE 2013; 4:94. [PMID: 23596453 PMCID: PMC3622885 DOI: 10.3389/fpls.2013.00094] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2013] [Accepted: 03/27/2013] [Indexed: 05/19/2023]
Abstract
Plant pathogens secrete effector proteins to promote host colonization. During infection of tomato xylem vessels, Fusarium oxysporum f. sp. lycopersici (Fol) secretes the Avr2 effector protein. Besides being a virulence factor, Avr2 is recognized intracellularly by the tomato I-2 resistance protein, resulting in the induction of host defenses. Here, we show that AVR2 is highly expressed in root- and xylem-colonizing hyphae three days post inoculation of roots. Co-expression of I-2 with AVR2 deletion constructs using agroinfiltration in Nicotiana benthamiana leaves revealed that, except for the N-terminal 17 amino acids, the entire AVR2 protein is required to trigger I-2-mediated cell death. The truncated Avr2 variants are still able to form homo-dimers, showing that the central region of Avr2 is required for dimerization. Simultaneous production of I-2 and Avr2 chimeras carrying various subcellular localization signals in N. benthamiana leaves revealed that a nuclear localization of Avr2 is required to trigger I-2-dependent cell death. Nuclear exclusion of Avr2 prevented its activation of I-2, suggesting that Avr2 is recognized by I-2 in the nucleus.
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Affiliation(s)
| | | | - Frank L. W. Takken
- *Correspondence: Frank L. W. Takken, Molecular Plant Pathology, Swammerdam Institute for Life Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, Netherlands. e-mail:
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Engelhardt S, Boevink PC, Armstrong MR, Ramos MB, Hein I, Birch PR. Relocalization of late blight resistance protein R3a to endosomal compartments is associated with effector recognition and required for the immune response. THE PLANT CELL 2012; 24:5142-58. [PMID: 23243124 PMCID: PMC3556980 DOI: 10.1105/tpc.112.104992] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2012] [Revised: 10/26/2012] [Accepted: 11/10/2012] [Indexed: 05/18/2023]
Abstract
An important objective of plant-pathogen interactions research is to determine where resistance proteins detect pathogen effectors to mount an immune response. Many nucleotide binding-Leucine-rich repeat (NB-LRR) resistance proteins accumulate in the plant nucleus following effector recognition, where they initiate the hypersensitive response (HR). Here, we show that potato (Solanum tuberosum) resistance protein R3a relocates from the cytoplasm to endosomal compartments only when coexpressed with recognized Phytophthora infestans effector form AVR3a(KI) and not unrecognized form AVR3a(EM). Moreover, AVR3a(KI), but not AVR3a(EM), is also relocalized to endosomes in the presence of R3a. Both R3a and AVR3a(KI) colocalized in close physical proximity at endosomes in planta. Treatment with brefeldin A (BFA) or wortmannin, inhibitors of the endocytic cycle, attenuated both the relocalization of R3a to endosomes and the R3a-mediated HR. No such effect of these inhibitors was observed on HRs triggered by the gene-for-gene pairs Rx1/PVX-CP and Sto1/IpiO1. An R3a(D501V) autoactive MHD mutant, which triggered HR in the absence of AVR3a(KI), failed to localize to endosomes. Moreover, BFA and wortmannin did not alter cell death triggered by this mutant. We conclude that effector recognition and consequent HR signaling by NB-LRR resistance protein R3a require its relocalization to vesicles in the endocytic pathway.
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Affiliation(s)
- Stefan Engelhardt
- Division of Plant Sciences, University of Dundee, Dundee DD2 5DA, United Kingdom
- Dundee Effector Consortium, James Hutton Institute, Invergowrie, Dundee DD2 5DA, United Kingdom
| | - Petra C. Boevink
- Dundee Effector Consortium, James Hutton Institute, Invergowrie, Dundee DD2 5DA, United Kingdom
- Cell and Molecular Sciences, James Hutton Institute, Invergowrie, Dundee DD2 5DA, United Kingdom
| | - Miles R. Armstrong
- Division of Plant Sciences, University of Dundee, Dundee DD2 5DA, United Kingdom
- Dundee Effector Consortium, James Hutton Institute, Invergowrie, Dundee DD2 5DA, United Kingdom
| | - Maria Brisa Ramos
- Division of Plant Sciences, University of Dundee, Dundee DD2 5DA, United Kingdom
- Cell and Molecular Sciences, James Hutton Institute, Invergowrie, Dundee DD2 5DA, United Kingdom
| | - Ingo Hein
- Dundee Effector Consortium, James Hutton Institute, Invergowrie, Dundee DD2 5DA, United Kingdom
- Cell and Molecular Sciences, James Hutton Institute, Invergowrie, Dundee DD2 5DA, United Kingdom
| | - Paul R.J. Birch
- Division of Plant Sciences, University of Dundee, Dundee DD2 5DA, United Kingdom
- Dundee Effector Consortium, James Hutton Institute, Invergowrie, Dundee DD2 5DA, United Kingdom
- Cell and Molecular Sciences, James Hutton Institute, Invergowrie, Dundee DD2 5DA, United Kingdom
- Address correspondence to
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128
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Lee DH, Kim DS, Hwang BK. The pepper RNA-binding protein CaRBP1 functions in hypersensitive cell death and defense signaling in the cytoplasm. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2012; 72:235-248. [PMID: 22640562 DOI: 10.1111/j.1365-313x.2012.05063.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The regulation of gene expression via post-transcriptional modification by RNA-binding proteins is crucial for plant disease and innate immunity. Here, we report the identification of the pepper (Capsicum annuum) RNA-binding protein1 gene (CaRBP1) as essential for hypersensitive cell death and defense signaling in the cytoplasm. CaRBP1 contains an RNA recognition motif and is rapidly and strongly induced in pepper by avirulent Xanthomonas campestris pv. vesicatoria (Xcv) infection. CaRBP1 displays in vitro RNA- and DNA-binding activity and in planta nucleocytoplasmic localization. Transient expression of CaRBP1 in pepper leaves triggers cell-death and defense responses. Notably, cytoplasmic localization of CaRBP1, mediated by the N-terminal region of CaRBP1, is essential for the hypersensitive cell-death response. Silencing of CaRBP1 in pepper plants significantly enhances susceptibility to avirulent Xcv infection. This is accompanied by compromised hypersensitive cell death, production of reactive oxygen species in oxidative bursts, expression of defense marker genes and accumulation of endogenous salicylic acid and jasmonic acid. Over-expression of CaRBP1 in Arabidopsis confers reduced susceptibility to infection by the biotrophic oomycete Hyaloperonospora arabidopsidis. Together, these results suggest that cytoplasmic localization of CaRBP1 is required for plant signaling of hypersensitive cell-death and defense responses.
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Affiliation(s)
- Dong Hyuk Lee
- Laboratory of Molecular Plant Pathology, School of Life Sciences and Biotechnology, Korea University, Anam-dong, Sungbuk-ku, Seoul 136-713, Korea
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129
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Takahashi H, Shoji H, Ando S, Kanayama Y, Kusano T, Takeshita M, Suzuki M, Masuta C. RCY1-mediated resistance to Cucumber mosaic virus is regulated by LRR domain-mediated interaction with CMV(Y) following degradation of RCY1. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2012; 25:1171-85. [PMID: 22852808 DOI: 10.1094/mpmi-04-12-0076-r] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
RCY1, which encodes a coiled coil nucleotide-binding site leucine-rich repeat (LRR) class R protein, confers the hypersensitive response (HR) to a yellow strain of Cucumber mosaic virus (CMV[Y]) in Arabidopsis thaliana. Nicotiana benthamiana transformed with hemagglutinin (HA) epitope-tagged RCY1 (RCY1-HA) also exhibited a defense response accompanied by HR cell death and induction of defense-related gene expression in response to CMV(Y). Following transient expression of RCY1-HA by agroinfiltration, the defense reaction was induced in N. benthamiana leaves infected with CMV(Y) but not in virulent CMV(B2)-infected N. benthamiana leaves transiently expressing RCY1-HA or CMV(Y)-infected N. benthamiana leaves transiently expressing HA-tagged RPP8 (RPP8-HA), which is allelic to RCY1. This result suggests that Arabidopsis RCY1-conferred resistance to CMV(Y) could be reproduced in N. benthamiana leaves in a gene-for-gene manner. Expression of a series of chimeric constructs between RCY1-HA and RPP8-HA in CMV(Y)-infected N. benthamiana indicated that induction of defense responses to CMV(Y) is regulated by the LRR domain of RCY1. Interestingly, in CMV(Y)-infected N. benthamiana manifesting the defense response, the levels of both RCY1 and chimeric proteins harboring the RCY1 LRR domain were significantly reduced. Taken together, these data indicate that the RCY1-conferred resistance response to CMV(Y) is regulated by an LRR domain-mediated interaction with CMV(Y) and seems to be tightly associated with the degradation of RCY1 in response to CMV(Y).
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130
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Du X, Miao M, Ma X, Liu Y, Kuhl JC, Martin GB, Xiao F. Plant programmed cell death caused by an autoactive form of Prf is suppressed by co-expression of the Prf LRR domain. MOLECULAR PLANT 2012; 5:1058-67. [PMID: 22451646 DOI: 10.1093/mp/sss014] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
In tomato, the NBARC-LRR resistance (R) protein Prf acts in concert with the Pto or Fen kinase to determine immunity against Pseudomonas syringae pv. tomato (Pst). Prf-mediated defense signaling is initiated by the recognition of two sequence-unrelated Pst-secreted effector proteins, AvrPto and AvrPtoB, by tomato Pto or Fen. Prf detects these interactions and activates signaling leading to host defense responses including localized programmed cell death (PCD) that is associated with the arrest of Pst growth. We found that Prf variants with single amino acid substitutions at D1416 in the IHD motif (isoleucine-histidine-aspartic acid) in the NBARC domain cause effector-independent PCD when transiently expressed in leaves of Nicotiana benthamiana, suggesting D1416 plays an important role in activation of Prf. The N-terminal region of Prf (NPrf) and the LRR domain are required for this autoactive Prf cell death signaling but dispensable for accumulation of the Prf(D1416V) protein. Significantly, co-expression of the Prf LRR but not NPrf, with Prf(D1416V), AvrPto/Pto, AvrPtoB/Pto, an autoactive form of Pto (Pto(Y207D)), or Fen completely suppresses PCD. However, the Prf LRR does not interfere with PCD caused by Rpi-blb1(D475V), a distinct R protein-mediated PCD signaling event, or that caused by overexpression of MAPKKKα, a protein acting downstream of Prf. Furthermore, we found the Prf(D1416V) protein is unable to accumulate in plant cells when co-expressed with the Prf LRR domain, likely explaining the cell death suppression. The mechanism for the LRR-induced degradation of Prf(D1416V) is unknown but may involve interference in the intramolecular interactions of Prf or to binding of the unattached LRR to other host proteins that are needed for Prf stability.
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Affiliation(s)
- Xinran Du
- Department of Plant, Soil and Entomological Sciences, University of Idaho, Moscow, ID 83844, USA
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131
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Heidrich K, Blanvillain-Baufumé S, Parker JE. Molecular and spatial constraints on NB-LRR receptor signaling. CURRENT OPINION IN PLANT BIOLOGY 2012; 15:385-91. [PMID: 22503757 DOI: 10.1016/j.pbi.2012.03.015] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2012] [Revised: 03/22/2012] [Accepted: 03/22/2012] [Indexed: 05/24/2023]
Abstract
In plants, a large polymorphic family of intracellular NB-LRR receptors lies at the heart of robust resistance to diverse pathogens and mechanisms by which these versatile molecular switches operate in effector-triggered immunity are beginning to emerge. We outline recent advances in our understanding of NB-LRR receptor signaling leading to disease resistance. Themes covered are (i) NB-LRR molecular constraining forces and their intimate relationship with receptor activation in different parts of the cell, (ii) cooperativity between NB-LRR proteins and the formation of higher order NB-LRR signaling complexes, and (iii) the spatial separation of different resistance branches within cells. Finally, we examine evidence for dynamic signaling across cell compartments in coordinating diverse immune outputs.
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Affiliation(s)
- Katharina Heidrich
- Department of Plant-Microbe Interactions, Max Planck Institute for Plant Breeding Research, Carl-von-Linne Weg 10, 50829 Cologne, Germany
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132
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Gassmann W, Bhattacharjee S. Effector-triggered immunity signaling: from gene-for-gene pathways to protein-protein interaction networks. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2012; 25:862-8. [PMID: 22414439 DOI: 10.1094/mpmi-01-12-0024-ia] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
In its simplicity and testability, Flor's gene-for-gene hypothesis has been a powerful driver in plant immunity research for decades. Once the molecular underpinnings of gene-for-gene resistance had come into sharper focus, there was a reassessment of Flor's hypothesis and a name change to effector-triggered immunity. As implied by the name change and exemplified by pioneering studies, plant immunity is increasingly described in terms of protein rather than genetic interactions. This progress leads to a reinterpretation of old concepts of pathogen recognition and resistance signaling and, of course, opens up new questions. Here, we provide a brief historical overview of resistance gene function and how a new focus on protein interactions can lead to a deeper understanding of the logic of plant innate immunity signaling.
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Affiliation(s)
- Walter Gassmann
- Christopher S. Bond Life Sciences Center and Interdisciplinary Plant Group, University of Missouri, Columbia, MO 65211, USA.
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Bai S, Liu J, Chang C, Zhang L, Maekawa T, Wang Q, Xiao W, Liu Y, Chai J, Takken FLW, Schulze-Lefert P, Shen QH. Structure-function analysis of barley NLR immune receptor MLA10 reveals its cell compartment specific activity in cell death and disease resistance. PLoS Pathog 2012; 8:e1002752. [PMID: 22685408 PMCID: PMC3369952 DOI: 10.1371/journal.ppat.1002752] [Citation(s) in RCA: 184] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2011] [Accepted: 04/30/2012] [Indexed: 11/18/2022] Open
Abstract
Plant intracellular immune receptors comprise a large number of multi-domain proteins resembling animal NOD-like receptors (NLRs). Plant NLRs typically recognize isolate-specific pathogen-derived effectors, encoded by avirulence (AVR) genes, and trigger defense responses often associated with localized host cell death. The barley MLA gene is polymorphic in nature and encodes NLRs of the coiled-coil (CC)-NB-LRR type that each detects a cognate isolate-specific effector of the barley powdery mildew fungus. We report the systematic analyses of MLA10 activity in disease resistance and cell death signaling in barley and Nicotiana benthamiana. MLA10 CC domain-triggered cell death is regulated by highly conserved motifs in the CC and the NB-ARC domains and by the C-terminal LRR of the receptor. Enforced MLA10 subcellular localization, by tagging with a nuclear localization sequence (NLS) or a nuclear export sequence (NES), shows that MLA10 activity in cell death signaling is suppressed in the nucleus but enhanced in the cytoplasm. By contrast, nuclear localized MLA10 is sufficient to mediate disease resistance against powdery mildew fungus. MLA10 retention in the cytoplasm was achieved through attachment of a glucocorticoid receptor hormone-binding domain (GR), by which we reinforced the role of cytoplasmic MLA10 in cell death signaling. Together with our data showing an essential and sufficient nuclear MLA10 activity in disease resistance, this suggests a bifurcation of MLA10-triggered cell death and disease resistance signaling in a compartment-dependent manner.
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Affiliation(s)
- Shiwei Bai
- State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
- Graduate University of Chinese Academy of Sciences, Beijing, China
| | - Jie Liu
- State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
- Graduate University of Chinese Academy of Sciences, Beijing, China
| | - Cheng Chang
- State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
- Graduate University of Chinese Academy of Sciences, Beijing, China
| | - Ling Zhang
- State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
| | - Takaki Maekawa
- Department of Plant Microbe Interactions, Max-Planck Institut Pflanzenzüchtungsforschung, Cologne, Germany
| | - Qiuyun Wang
- State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
| | - Wenkai Xiao
- State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
| | - Yule Liu
- School of Life Sciences, Tsinghua University, Beijing, China
| | - Jijie Chai
- School of Life Sciences, Tsinghua University, Beijing, China
| | - Frank L. W. Takken
- Molecular Plant Pathology, Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, The Netherlands
- Centre for BioSystem Genomics, Wageningen, The Netherlands
| | - Paul Schulze-Lefert
- Department of Plant Microbe Interactions, Max-Planck Institut Pflanzenzüchtungsforschung, Cologne, Germany
| | - Qian-Hua Shen
- State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
- * E-mail:
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134
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Qi D, DeYoung BJ, Innes RW. Structure-function analysis of the coiled-coil and leucine-rich repeat domains of the RPS5 disease resistance protein. PLANT PHYSIOLOGY 2012; 158:1819-1832. [PMID: 22331412 DOI: 10.2307/41496322] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The Arabidopsis (Arabidopsis thaliana) RESISTANCE TO PSEUDOMONAS SYRINGAE5 (RPS5) disease resistance protein mediates recognition of the Pseudomonas syringae effector protein AvrPphB. RPS5 belongs to the coiled-coil-nucleotide-binding site-leucine-rich repeat (CC-NBS-LRR) family and is activated by AvrPphB-mediated cleavage of the protein kinase PBS1. Here, we present a structure-function analysis of the CC and LRR domains of RPS5 using transient expression assays in Nicotiana benthamiana. We found that substituting the CC domain of RPS2 for the RPS5 CC domain did not alter RPS5 specificity and only moderately reduced its ability to activate programmed cell death, suggesting that the CC domain does not play a direct role in the recognition of PBS1 cleavage. Analysis of an RPS5-super Yellow Fluorescent Protein fusion revealed that RPS5 localizes to the plasma membrane (PM). Alanine substitutions of predicted myristoylation (glycine-2) and palmitoylation (cysteine-4) residues affected RPS5 PM localization, protein stability, and function in an additive manner, indicating that PM localization is essential to RPS5 function. The first 20 amino acids of RPS5 were sufficient for directing super Yellow Fluorescent Protein to the PM. C-terminal truncations of RPS5 revealed that the first four LRR repeats are sufficient for inhibiting RPS5 autoactivation; however, the complete LRR domain was required for the recognition of PBS1 cleavage. Substitution of the RPS2 LRR domain resulted in the autoactivation of RPS5, indicating that the LRR domain must coevolve with the NBS domain. We conclude that the RPS5 LRR domain functions to suppress RPS5 activation in the absence of PBS1 cleavage and promotes RPS5 activation in its presence.
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Affiliation(s)
- Dong Qi
- Department of Biology, Indiana University, Bloomington, Indiana 47405, USA
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135
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Qi D, DeYoung BJ, Innes RW. Structure-function analysis of the coiled-coil and leucine-rich repeat domains of the RPS5 disease resistance protein. PLANT PHYSIOLOGY 2012; 158:1819-32. [PMID: 22331412 PMCID: PMC3320188 DOI: 10.1104/pp.112.194035] [Citation(s) in RCA: 153] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2012] [Accepted: 02/07/2012] [Indexed: 05/18/2023]
Abstract
The Arabidopsis (Arabidopsis thaliana) RESISTANCE TO PSEUDOMONAS SYRINGAE5 (RPS5) disease resistance protein mediates recognition of the Pseudomonas syringae effector protein AvrPphB. RPS5 belongs to the coiled-coil-nucleotide-binding site-leucine-rich repeat (CC-NBS-LRR) family and is activated by AvrPphB-mediated cleavage of the protein kinase PBS1. Here, we present a structure-function analysis of the CC and LRR domains of RPS5 using transient expression assays in Nicotiana benthamiana. We found that substituting the CC domain of RPS2 for the RPS5 CC domain did not alter RPS5 specificity and only moderately reduced its ability to activate programmed cell death, suggesting that the CC domain does not play a direct role in the recognition of PBS1 cleavage. Analysis of an RPS5-super Yellow Fluorescent Protein fusion revealed that RPS5 localizes to the plasma membrane (PM). Alanine substitutions of predicted myristoylation (glycine-2) and palmitoylation (cysteine-4) residues affected RPS5 PM localization, protein stability, and function in an additive manner, indicating that PM localization is essential to RPS5 function. The first 20 amino acids of RPS5 were sufficient for directing super Yellow Fluorescent Protein to the PM. C-terminal truncations of RPS5 revealed that the first four LRR repeats are sufficient for inhibiting RPS5 autoactivation; however, the complete LRR domain was required for the recognition of PBS1 cleavage. Substitution of the RPS2 LRR domain resulted in the autoactivation of RPS5, indicating that the LRR domain must coevolve with the NBS domain. We conclude that the RPS5 LRR domain functions to suppress RPS5 activation in the absence of PBS1 cleavage and promotes RPS5 activation in its presence.
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Affiliation(s)
| | | | - Roger W. Innes
- Department of Biology, Indiana University, Bloomington, Indiana 47405
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136
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Choi DS, Hwang IS, Hwang BK. Requirement of the cytosolic interaction between PATHOGENESIS-RELATED PROTEIN10 and LEUCINE-RICH REPEAT PROTEIN1 for cell death and defense signaling in pepper. THE PLANT CELL 2012; 24:1675-90. [PMID: 22492811 PMCID: PMC3398571 DOI: 10.1105/tpc.112.095869] [Citation(s) in RCA: 149] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2012] [Revised: 03/16/2012] [Accepted: 03/21/2012] [Indexed: 05/18/2023]
Abstract
Plants recruit innate immune receptors such as leucine-rich repeat (LRR) proteins to recognize pathogen attack and activate defense genes. Here, we identified the pepper (Capsicum annuum) pathogenesis-related protein10 (PR10) as a leucine-rich repeat protein1 (LRR1)-interacting partner. Bimolecular fluorescence complementation and coimmunoprecipitation assays confirmed the specific interaction between LRR1 and PR10 in planta. Avirulent Xanthomonas campestris pv vesicatoria infection induces PR10 expression associated with the hypersensitive cell death response. Transient expression of PR10 triggers hypersensitive cell death in pepper and Nicotiana benthamiana leaves, which is amplified by LRR1 coexpression as a positive regulator. LRR1 promotes the ribonuclease activity and phosphorylation of PR10, leading to enhanced cell death signaling. The LRR1-PR10 complex is formed in the cytoplasm, resulting in its secretion into the apoplastic space. Engineered nuclear confinement of both proteins revealed that the cytoplasmic localization of the PR10-LRR1 complex is essential for cell death-mediated defense signaling. PR10/LRR1 silencing in pepper compromises resistance to avirulent X. campestris pv vesicatoria infection. By contrast, PR10/LRR1 overexpression in Arabidopsis thaliana confers enhanced resistance to Pseudomonas syringae pv tomato and Hyaloperonospora arabidopsidis. Together, these results suggest that the cytosolic LRR-PR10 complex is responsible for cell death-mediated defense signaling.
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Affiliation(s)
- Du Seok Choi
- Laboratory of Molecular Plant Pathology, School of Life Sciences and Biotechnology, Korea University, Seoul 136-713, Republic of Korea
| | | | - Byung Kook Hwang
- Laboratory of Molecular Plant Pathology, School of Life Sciences and Biotechnology, Korea University, Seoul 136-713, Republic of Korea
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137
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Mang HG, Qian W, Zhu Y, Qian J, Kang HG, Klessig DF, Hua J. Abscisic acid deficiency antagonizes high-temperature inhibition of disease resistance through enhancing nuclear accumulation of resistance proteins SNC1 and RPS4 in Arabidopsis. THE PLANT CELL 2012; 24:1271-84. [PMID: 22454454 PMCID: PMC3336126 DOI: 10.1105/tpc.112.096198] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2012] [Revised: 02/28/2012] [Accepted: 03/08/2012] [Indexed: 05/20/2023]
Abstract
Plant defense responses to pathogens are influenced by abiotic factors, including temperature. Elevated temperatures often inhibit the activities of disease resistance proteins and the defense responses they mediate. A mutant screen with an Arabidopsis thaliana temperature-sensitive autoimmune mutant bonzai1 revealed that the abscisic acid (ABA)-deficient mutant aba2 enhances resistance mediated by the resistance (R) gene suppressor of npr1-1 constitutive1 (SNC1) at high temperature. ABA deficiency promoted nuclear accumulation of SNC1, which was essential for it to function at low and high temperatures. Furthermore, the effect of ABA deficiency on SNC1 protein accumulation is independent of salicylic acid, whose effects are often antagonized by ABA. ABA deficiency also promotes the activity and nuclear localization of R protein resistance to Pseudomonas syringae4 at higher temperature, suggesting that the effect of ABA on R protein localization and nuclear activity is rather broad. By contrast, mutations that confer ABA insensitivity did not promote defense responses at high temperature, suggesting either tissue specificity of ABA signaling or a role of ABA in defense regulation independent of the core ABA signaling machinery. Taken together, this study reveals a new intersection between ABA and disease resistance through R protein localization and provides further evidence of antagonism between abiotic and biotic responses.
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Affiliation(s)
- Hyung-Gon Mang
- Department of Plant Biology, Cornell University, Ithaca, New York 14853
| | - Weiqiang Qian
- Department of Plant Biology, Cornell University, Ithaca, New York 14853
| | - Ying Zhu
- Department of Plant Biology, Cornell University, Ithaca, New York 14853
- State Key Laboratory Breeding Base for Zhejiang Sustainable Pest and Disease Control, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China
| | - Jun Qian
- Department of Plant Biology, Cornell University, Ithaca, New York 14853
| | - Hong-Gu Kang
- Boyce Thompson Institute, Ithaca, New York 14853
- Department of Biology, Texas State University, San Marcos, Texas 78666
| | | | - Jian Hua
- Department of Plant Biology, Cornell University, Ithaca, New York 14853
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Bonardi V, Cherkis K, Nishimura MT, Dangl JL. A new eye on NLR proteins: focused on clarity or diffused by complexity? Curr Opin Immunol 2012; 24:41-50. [PMID: 22305607 DOI: 10.1016/j.coi.2011.12.006] [Citation(s) in RCA: 121] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2011] [Accepted: 12/21/2011] [Indexed: 11/26/2022]
Abstract
The nucleotide-binding domain leucine-rich repeat proteins (NLRs) represent the major class of intracellular innate immune receptors in plants and animals. Understanding their functions is a major challenge in immunology. This review highlights recent efforts toward elucidating NLR functions in human and plants. We compare unconventional aspects of NLR proteins across the two kingdoms. We review recent advances describing P-loop independent activation, nuclear-cytoplasmic trafficking, oligomerization and multimerization requirements for signaling, and for expanded functions beyond pathogen recognition by several NLR proteins.
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Affiliation(s)
- Vera Bonardi
- Department of Biology, University of North Carolina, Chapel Hill, NC 27599-3280, USA
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139
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Balazadeh S, Jaspert N, Arif M, Mueller-Roeber B, Maurino VG. Expression of ROS-responsive genes and transcription factors after metabolic formation of H(2)O(2) in chloroplasts. FRONTIERS IN PLANT SCIENCE 2012; 3:234. [PMID: 23125844 PMCID: PMC3485569 DOI: 10.3389/fpls.2012.00234] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2012] [Accepted: 10/01/2012] [Indexed: 05/04/2023]
Abstract
Glycolate oxidase (GO) catalyses the oxidation of glycolate to glyoxylate, thereby consuming O(2) and producing H(2)O(2). In this work, Arabidopsis thaliana plants expressing GO in the chloroplasts (GO plants) were used to assess the expressional behavior of reactive oxygen species (ROS)-responsive genes and transcription factors (TFs) after metabolic induction of H(2)O(2) formation in chloroplasts. In this organelle, GO uses the glycolate derived from the oxygenase activity of RubisCO. Here, to identify genes responding to an abrupt production of H(2)O(2) in chloroplasts we used quantitative real-time PCR (qRT-PCR) to test the expression of 187 ROS-responsive genes and 1880 TFs after transferring GO and wild-type (WT) plants grown at high CO(2) levels to ambient CO(2) concentration. Our data revealed coordinated expression changes of genes of specific functional networks 0.5 h after metabolic induction of H(2)O(2) production in GO plants, including the induction of indole glucosinolate and camalexin biosynthesis genes. Comparative analysis using available microarray data suggests that signals for the induction of these genes through H(2)O(2) may originate in the chloroplast. The TF profiling indicated an up-regulation in GO plants of a group of genes involved in the regulation of proanthocyanidin and anthocyanin biosynthesis. Moreover, the upregulation of expression of TF and TF-interacting proteins affecting development (e.g., cell division, stem branching, flowering time, flower development) would impact growth and reproductive capacity, resulting in altered development under conditions that promote the formation of H(2)O(2).
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Affiliation(s)
- Salma Balazadeh
- Institute of Biochemistry and Biology, University of PotsdamPotsdam, Germany
| | - Nils Jaspert
- Plant Molecular Physiology and Biotechnology, Center of Excellence on Plant Sciences, Heinrich-Heine-UniversityDüsseldorf, Germany
| | - Muhammad Arif
- Institute of Biochemistry and Biology, University of PotsdamPotsdam, Germany
| | | | - Veronica G. Maurino
- Plant Molecular Physiology and Biotechnology, Center of Excellence on Plant Sciences, Heinrich-Heine-UniversityDüsseldorf, Germany
- *Correspondence: Veronica G. Maurino, Entwicklungs- und Molekularbiologie der Pflanzen, Heinrich-Heine-Universität, Universitätsstraße 1, 40225 Düsseldorf, Germany. e-mail:
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140
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Bernoux M, Ellis JG, Dodds PN. New insights in plant immunity signaling activation. CURRENT OPINION IN PLANT BIOLOGY 2011; 14:512-8. [PMID: 21723182 PMCID: PMC3191233 DOI: 10.1016/j.pbi.2011.05.005] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2011] [Revised: 05/17/2011] [Accepted: 05/26/2011] [Indexed: 05/19/2023]
Abstract
Plant disease resistance can be triggered by specific recognition of microbial effectors by plant nucleotide binding-leucine rich repeat (NB-LRR) receptors. Over the last few years, many efforts have greatly improved the understanding of effector and NB-LRR function, but have left a lot of questions as to how effector perception activates NB-LRR induction of defense signaling. This review describes exciting new findings showing similarities and differences in function of diverse plant NB-LRR proteins in terms of pathogen recognition and where and how resistance proteins are activated. Localization studies have shown that some NB-LRRs can activate signaling from the cytosol while others act in the nucleus. Also, the structural determination of two NB-LRR signaling domains demonstrated that receptor oligomerization is fundamental for the activation of resistance signaling.
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Affiliation(s)
- Maud Bernoux
- CSIRO Plant Industry, Canberra, Australian Capital Territory 2601, Australia
| | - Jeffrey G. Ellis
- CSIRO Plant Industry, Canberra, Australian Capital Territory 2601, Australia
| | - Peter N. Dodds
- CSIRO Plant Industry, Canberra, Australian Capital Territory 2601, Australia
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