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1.
Nature ; 610(7932): 532-539, 2022 10.
Artigo em Inglês | MEDLINE | ID: mdl-36163289

RESUMO

Plant intracellular nucleotide-binding leucine-rich repeat receptors (NLRs) detect pathogen effectors to trigger immune responses1. Indirect recognition of a pathogen effector by the dicotyledonous Arabidopsis thaliana coiled-coil domain containing NLR (CNL) ZAR1 induces the formation of a large hetero-oligomeric protein complex, termed the ZAR1 resistosome, which functions as a calcium channel required for ZAR1-mediated immunity2-4. Whether the resistosome and channel activities are conserved among plant CNLs remains unknown. Here we report the cryo-electron microscopy structure of the wheat CNL Sr355 in complex with the effector AvrSr356 of the wheat stem rust pathogen. Direct effector binding to the leucine-rich repeats of Sr35 results in the formation of a pentameric Sr35-AvrSr35 complex, which we term the Sr35 resistosome. Wheat Sr35 and Arabidopsis ZAR1 resistosomes bear striking structural similarities, including an arginine cluster in the leucine-rich repeats domain not previously recognized as conserved, which co-occurs and forms intramolecular interactions with the 'EDVID' motif in the coiled-coil domain. Electrophysiological measurements show that the Sr35 resistosome exhibits non-selective cation channel activity. These structural insights allowed us to generate new variants of closely related wheat and barley orphan NLRs that recognize AvrSr35. Our data support the evolutionary conservation of CNL resistosomes in plants and demonstrate proof of principle for structure-based engineering of NLRs for crop improvement.


Assuntos
Canais de Cálcio , Microscopia Crioeletrônica , Proteínas NLR , Proteínas de Plantas , Receptores Imunológicos , Triticum , Arabidopsis/imunologia , Arabidopsis/metabolismo , Arginina , Canais de Cálcio/química , Canais de Cálcio/imunologia , Canais de Cálcio/metabolismo , Cátions/metabolismo , Leucina , Proteínas NLR/química , Proteínas NLR/imunologia , Proteínas NLR/metabolismo , Doenças das Plantas/imunologia , Doenças das Plantas/microbiologia , Imunidade Vegetal , Proteínas de Plantas/química , Proteínas de Plantas/imunologia , Proteínas de Plantas/metabolismo , Receptores Imunológicos/química , Receptores Imunológicos/imunologia , Receptores Imunológicos/metabolismo , Triticum/imunologia , Triticum/metabolismo , Motivos de Aminoácidos , Sequência Conservada , Eletrofisiologia
2.
Science ; 377(6605): eabq8180, 2022 07 29.
Artigo em Inglês | MEDLINE | ID: mdl-35857644

RESUMO

Plant pathogen-activated immune signaling by nucleotide-binding leucine-rich repeat (NLR) receptors with an N-terminal Toll/interleukin-1 receptor (TIR) domain converges on Enhanced Disease Susceptibility 1 (EDS1) and its direct partners, Phytoalexin Deficient 4 (PAD4) or Senescence-Associated Gene 101 (SAG101). TIR-encoded nicotinamide adenine dinucleotide hydrolase (NADase) produces signaling molecules to promote exclusive EDS1-PAD4 and EDS1-SAG101 interactions with helper NLR subclasses. In this work, we show that TIR-containing proteins catalyze adenosine diphosphate (ADP)-ribosylation of adenosine triphosphate (ATP) and ADP ribose (ADPR) through ADPR polymerase-like and NADase activity, forming ADP-ribosylated ATP (ADPr-ATP) and ADPr-ADPR (di-ADPR), respectively. Specific binding of ADPr-ATP or di-ADPR allosterically promotes EDS1-SAG101 interaction with helper NLR N requirement gene 1A (NRG1A) in vitro and in planta. Our data reveal an enzymatic activity of TIRs that enables specific activation of the EDS1-SAG101-NRG1 immunity branch.


Assuntos
ADP-Ribosilação , Difosfato de Adenosina , Proteínas de Arabidopsis , Arabidopsis , Hidrolases de Éster Carboxílico , Proteínas de Ligação a DNA , Peptídeos e Proteínas de Sinalização Intracelular , Imunidade Vegetal , Difosfato de Adenosina/metabolismo , Trifosfato de Adenosina/metabolismo , Arabidopsis/enzimologia , Arabidopsis/imunologia , Proteínas de Arabidopsis/metabolismo , Hidrolases de Éster Carboxílico/química , Hidrolases de Éster Carboxílico/genética , Hidrolases de Éster Carboxílico/metabolismo , Proteínas de Ligação a DNA/metabolismo , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , NAD+ Nucleosidase/metabolismo
3.
Science ; 377(6605): eabq3297, 2022 07 29.
Artigo em Inglês | MEDLINE | ID: mdl-35857645

RESUMO

Plant nucleotide-binding leucine-rich repeat-containing (NLR) receptors with an N-terminal Toll/interleukin-1 receptor (TIR) domain sense pathogen effectors to enable TIR-encoded nicotinamide adenine dinucleotide hydrolase (NADase) activity for immune signaling. TIR-NLR signaling requires the helper NLRs N requirement gene 1 (NRG1), Activated Disease Resistance 1 (ADR1), and Enhanced Disease Susceptibility 1 (EDS1), which forms a heterodimer with each of its paralogs Phytoalexin Deficient 4 (PAD4) and Senescence-Associated Gene 101 (SAG101). Here, we show that TIR-containing proteins catalyze the production of 2'-(5''-phosphoribosyl)-5'-adenosine monophosphate (pRib-AMP) and diphosphate (pRib-ADP) in vitro and in planta. Biochemical and structural data demonstrate that EDS1-PAD4 is a receptor complex for pRib-AMP and pRib-ADP, which allosterically promote EDS1-PAD4 interaction with ADR1-L1 but not NRG1A. Our study identifies TIR-catalyzed pRib-AMP and pRib-ADP as a missing link in TIR signaling through EDS1-PAD4 and as likely second messengers for plant immunity.


Assuntos
Difosfato de Adenosina , Monofosfato de Adenosina , Proteínas de Arabidopsis , Arabidopsis , Hidrolases de Éster Carboxílico , Proteínas de Ligação a DNA , Imunidade Vegetal , Difosfato de Adenosina/metabolismo , Monofosfato de Adenosina/metabolismo , Arabidopsis/enzimologia , Arabidopsis/imunologia , Proteínas de Arabidopsis/química , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Hidrolases de Éster Carboxílico/química , Hidrolases de Éster Carboxílico/genética , Hidrolases de Éster Carboxílico/metabolismo , Catálise , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Imunidade Vegetal/genética
4.
Nature ; 607(7918): 339-344, 2022 07.
Artigo em Inglês | MEDLINE | ID: mdl-35768511

RESUMO

Extreme weather conditions associated with climate change affect many aspects of plant and animal life, including the response to infectious diseases. Production of salicylic acid (SA), a central plant defence hormone1-3, is particularly vulnerable to suppression by short periods of hot weather above the normal plant growth temperature range via an unknown mechanism4-7. Here we show that suppression of SA production in Arabidopsis thaliana at 28 °C is independent of PHYTOCHROME B8,9 (phyB) and EARLY FLOWERING 310 (ELF3), which regulate thermo-responsive plant growth and development. Instead, we found that formation of GUANYLATE BINDING PROTEIN-LIKE 3 (GBPL3) defence-activated biomolecular condensates11 (GDACs) was reduced at the higher growth temperature. The altered GDAC formation in vivo is linked to impaired recruitment of GBPL3 and SA-associated Mediator subunits to the promoters of CBP60g and SARD1, which encode master immune transcription factors. Unlike many other SA signalling components, including the SA receptor and biosynthetic genes, optimized CBP60g expression was sufficient to broadly restore SA production, basal immunity and effector-triggered immunity at the elevated growth temperature without significant growth trade-offs. CBP60g family transcription factors are widely conserved in plants12. These results have implications for safeguarding the plant immune system as well as understanding the concept of the plant-pathogen-environment disease triangle and the emergence of new disease epidemics in a warming climate.


Assuntos
Aclimatação , Proteínas de Arabidopsis , Arabidopsis , Meio Ambiente , Aquecimento Global , Imunidade Vegetal , Temperatura , Arabidopsis/crescimento & desenvolvimento , Arabidopsis/imunologia , Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Proteínas de Ligação a Calmodulina/genética , Regulação da Expressão Gênica de Plantas , Aquecimento Global/estatística & dados numéricos , Interações Hospedeiro-Patógeno , Fitocromo B , Doenças das Plantas/genética , Imunidade Vegetal/genética , Ácido Salicílico/metabolismo , Fatores de Transcrição
5.
Science ; 376(6595): 857-860, 2022 05 20.
Artigo em Inglês | MEDLINE | ID: mdl-35587979

RESUMO

In plants, many invading microbial pathogens are recognized by cell-surface pattern recognition receptors, which induce defense responses. Here, we show that the ceramide Phytophthora infestans-ceramide D (Pi-Cer D) from the plant pathogenic oomycete P. infestans triggers defense responses in Arabidopsis. Pi-Cer D is cleaved by an Arabidopsis apoplastic ceramidase, NEUTRAL CERAMIDASE 2 (NCER2), and the resulting 9-methyl-branched sphingoid base is recognized by a plasma membrane lectin receptor-like kinase, RESISTANT TO DFPM-INHIBITION OF ABSCISIC ACID SIGNALING 2 (RDA2). 9-Methyl-branched sphingoid base is specific to microbes and induces plant immune responses by physically interacting with RDA2. Loss of RDA2 or NCER2 function compromised Arabidopsis resistance against an oomycete pathogen. Thus, we elucidated the recognition mechanisms of pathogen-derived lipid molecules in plants.


Assuntos
Proteínas de Arabidopsis , Arabidopsis , Ceramidas , Interações Hospedeiro-Patógeno , Ceramidase Neutra , Phytophthora infestans , Doenças das Plantas , Arabidopsis/genética , Arabidopsis/imunologia , Arabidopsis/microbiologia , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Ceramidas/metabolismo , Ceramidase Neutra/genética , Ceramidase Neutra/metabolismo , Phytophthora infestans/patogenicidade , Doenças das Plantas/imunologia , Doenças das Plantas/microbiologia , Proteínas Serina-Treonina Quinases/genética , Proteínas Serina-Treonina Quinases/metabolismo , Receptores Mitogênicos/genética , Receptores Mitogênicos/metabolismo
6.
Int J Mol Sci ; 23(4)2022 Feb 16.
Artigo em Inglês | MEDLINE | ID: mdl-35216293

RESUMO

Changing temperatures are known to affect plant-microbe interactions; however, the molecular mechanism involved in plant disease resistance is not well understood. Here, we report the effects of a moderate change in temperature on plant immune response through Ca2+/calmodulin-mediated signaling. At 30 °C, Pst DC3000 triggered significantly weak and relatively slow Ca2+ influx in plant cells, as compared to that at 18 °C. Increased temperature contributed to an enhanced disease susceptibility in plants; the enhanced disease susceptibility is the result of the compromised stomatal closure induced by pathogens at high temperature. A Ca2+ receptor, AtSR1, contributes to the decreased plant immunity at high temperatures and the calmodulin-binding domain (CaMBD) is required for its function. Furthermore, both salicylic acid biosynthesis (ICS) and salicylic acid receptor (NPR1) are involved in this process. In addition to stomatal control, AtSR1 is involved in high temperature-compromised apoplastic immune response through the salicylic acid signaling pathway. The qRT-PCR data revealed that AtSR1 contributed to increased temperatures-mediated susceptible immune response by regulating SA-related genes in atsr1, such as PR1, ICS1, NPR1, as well as EDS1. Our results indicate that Ca2+ signaling has broad effects on the molecular interplay between changing temperatures as well as plant defense during plant-pathogen interactions.


Assuntos
Proteínas de Arabidopsis , Arabidopsis , Sinalização do Cálcio , Fatores de Transcrição , Arabidopsis/imunologia , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Calmodulina/metabolismo , Suscetibilidade a Doenças , Regulação da Expressão Gênica de Plantas , Doenças das Plantas/genética , Imunidade Vegetal , Ácido Salicílico/metabolismo , Temperatura , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo
7.
Plant Cell Environ ; 45(6): 1843-1861, 2022 06.
Artigo em Inglês | MEDLINE | ID: mdl-35199374

RESUMO

Stomatal movement participates in plant immunity by directly affecting the invasion of bacteria, but the genes that regulate stomatal immunity have not been well identified. Here, we characterised the function of the bZIP59 transcription factor from Arabidopsis thaliana, which is constitutively expressed in guard cells. The bzip59 mutant is partially impaired in stomatal closure induced by Pseudomonas syringae pv. tomato strain (Pst) DC3000 and is more susceptible to Pst DC3000 infection. By contrast, the line overexpressing bZIP59 enhances resistance to Pst DC3000 infection. Furthermore, the bzip59 mutant is also partially impaired in stomatal closure induced by flagellin flg22 derived from Pst DC3000, and epistasis analysis revealed that bZIP59 acts upstream of reactive oxygen species (ROS) and nitric oxide (NO) and downstream of salicylic acid signalling in flg22-induced stomatal closure. In addition, the bzip59 mutant showed resistance and sensitivity to Sclerotinia sclerotiorum and Tobacco mosaic virus that do not invade through stomata, respectively. Collectively, our results demonstrate that bZIP59 plays an important role in the stomatal immunity and reveal that the same transcription factor can positively and negatively regulate disease resistance against different pathogens.


Assuntos
Proteínas de Arabidopsis , Arabidopsis , Fatores de Transcrição de Zíper de Leucina Básica , Arabidopsis/genética , Arabidopsis/imunologia , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/imunologia , Fatores de Transcrição de Zíper de Leucina Básica/genética , Fatores de Transcrição de Zíper de Leucina Básica/imunologia , Doenças das Plantas/genética , Doenças das Plantas/imunologia , Doenças das Plantas/microbiologia , Imunidade Vegetal , Estômatos de Plantas/genética , Estômatos de Plantas/imunologia , Pseudomonas syringae/fisiologia , Fatores de Transcrição/genética
8.
Plant Cell ; 34(1): 679-697, 2022 01 20.
Artigo em Inglês | MEDLINE | ID: mdl-34599338

RESUMO

Immune responses are triggered when pattern recognition receptors recognize microbial molecular patterns. The Arabidopsis (Arabidopsis thaliana) receptor-like cytoplasmic kinase BOTRYTIS-INDUCED KINASE1 (BIK1) acts as a signaling hub of plant immunity. BIK1 homeostasis is maintained by a regulatory module in which CALCIUM-DEPENDENT PROTEIN KINASE28 (CPK28) regulates BIK1 turnover via the activities of two E3 ligases. Immune-induced alternative splicing of CPK28 attenuates CPK28 function. However, it remained unknown whether CPK28 is under proteasomal control. Here, we demonstrate that CPK28 undergoes ubiquitination and 26S proteasome-mediated degradation, which is enhanced by flagellin treatment. Two closely related ubiquitin ligases, ARABIDOPSIS TÓXICOS EN LEVADURA31 (ATL31) and ATL6, specifically interact with CPK28 at the plasma membrane; this association is enhanced by flagellin elicitation. ATL31/6 directly ubiquitinate CPK28, resulting in its proteasomal degradation. Furthermore, ATL31/6 promotes the stability of BIK1 by mediating CPK28 degradation. Consequently, ATL31/6 positively regulate BIK1-mediated immunity. Our findings reveal another mechanism for attenuating CPK28 function to maintain BIK1 homeostasis and enhance immune responses.


Assuntos
Proteínas de Arabidopsis/genética , Arabidopsis/genética , Imunidade Vegetal/genética , Complexo de Endopeptidases do Proteassoma/metabolismo , Proteínas Quinases/genética , Ubiquitina-Proteína Ligases/genética , Arabidopsis/imunologia , Proteínas de Arabidopsis/metabolismo , Proteínas Quinases/metabolismo , Transdução de Sinais , Ubiquitina-Proteína Ligases/metabolismo
9.
Plant Physiol ; 188(1): 70-80, 2022 01 20.
Artigo em Inglês | MEDLINE | ID: mdl-34633454

RESUMO

Nicotiana benthamiana has emerged as a complementary experimental system to Arabidopsis thaliana. It enables fast-forward in vivo analyses primarily through transient gene expression and is particularly popular in the study of plant immunity. Recently, our understanding of nucleotide-binding leucine-rich repeat (NLR) plant immune receptors has greatly advanced following the discovery of the Arabidopsis HOPZ-ACTIVATED RESISTANCE1 (ZAR1) resistosome. Here, we describe a vector system of 72 plasmids that enables functional studies of the ZAR1 resistosome in N. benthamiana. We showed that ZAR1 stands out among the coiled coil class of NLRs (CC-NLRs) for being highly conserved across distantly related dicot plant species and confirmed NbZAR1 as the N. benthamiana ortholog of Arabidopsis ZAR1. Effector-activated and autoactive NbZAR1 triggers the cell death response in N. benthamiana and this activity is dependent on a functional N-terminal α1 helix. C-terminally tagged NbZAR1 remains functional in N. benthamiana, thus enabling cell biology and biochemical studies in this plant system. We conclude that the NbZAR1 open source pZA plasmid collection forms an additional experimental system to Arabidopsis for in planta resistosome studies.


Assuntos
Arabidopsis/genética , Arabidopsis/imunologia , Resistência à Doença/genética , Doenças das Plantas/genética , Doenças das Plantas/imunologia , Tabaco/genética , Tabaco/imunologia , Arabidopsis/microbiologia , Regulação da Expressão Gênica de Plantas , Genes de Plantas , Tabaco/microbiologia
10.
Plant Cell ; 34(1): 374-394, 2022 01 20.
Artigo em Inglês | MEDLINE | ID: mdl-34726756

RESUMO

The assembly of macromolecules on the plasma membrane concentrates cell surface biomolecules into nanometer- to micrometer-scale clusters (nano- or microdomains) that help the cell initiate or respond to signals. In plant-microbe interactions, the actin cytoskeleton undergoes rapid remodeling during pathogen-associated molecular pattern-triggered immunity (PTI). The nanoclustering of formin-actin nucleator proteins at the cell surface has been identified as underlying actin nucleation during plant innate immune responses. Here, we show that the condensation of nanodomain constituents and the self-assembly of remorin proteins enables this mechanism of controlling formin condensation and activity during innate immunity in Arabidopsis thaliana. Through intrinsically disordered region-mediated remorin oligomerization and formin interaction, remorin gradually recruits and condenses formins upon PTI activation in lipid bilayers, consequently increasing actin nucleation in a time-dependent manner postinfection. Such nanodomain- and remorin-mediated regulation of plant surface biomolecules is expected to be a general feature of plant innate immune responses that creates spatially separated biochemical compartments and fine tunes membrane physicochemical properties for transduction of immune signals in the host.


Assuntos
Citoesqueleto de Actina/metabolismo , Proteínas de Arabidopsis/metabolismo , Arabidopsis/imunologia , Forminas/metabolismo , Imunidade Vegetal/genética , Actinas/metabolismo , Arabidopsis/genética , Imunidade Inata/genética
11.
Plant Cell ; 34(1): 395-417, 2022 01 20.
Artigo em Inglês | MEDLINE | ID: mdl-34791473

RESUMO

Outer membrane vesicles (OMVs) are released from the outer membranes of Gram-negative bacteria during infection and modulate host immunity during host-pathogen interactions. The mechanisms by which OMVs are perceived by plants and affect host immunity are unclear. Here, we used the pathogen Xanthomonas campestris pv. campestris to demonstrate that OMV-plant interactions at the Arabidopsis thaliana plasma membrane (PM) modulate various host processes, including endocytosis, innate immune responses, and suppression of pathogenesis by phytobacteria. The lipid phase of OMVs is highly ordered and OMVs directly insert into the Arabidopsis PM, thereby enhancing the plant PM's lipid order; this also resulted in strengthened plant defenses. Strikingly, the integration of OMVs into the plant PM is host nanodomain- and remorin-dependent. Using coarse-grained simulations of molecular dynamics, we demonstrated that OMV integration into the plant PM depends on the membrane lipid order. Our computational simulations further showed that the saturation level of the OMV lipids could fine-tune the enhancement of host lipid order. Our work unraveled the mechanisms underlying the ability of OMVs produced by a plant pathogen to insert into the host PM, alter host membrane properties, and modulate plant immune responses.


Assuntos
Arabidopsis/imunologia , Membrana Externa Bacteriana/imunologia , Interações Hospedeiro-Patógeno , Imunidade Vegetal , Xanthomonas campestris/fisiologia
12.
New Phytol ; 233(5): 2249-2265, 2022 03.
Artigo em Inglês | MEDLINE | ID: mdl-34918346

RESUMO

Plants use pattern recognition receptors (PRRs) to detect pathogen-associated molecular patterns (PAMPs) and activate pattern-triggered immunity (PTI). Precise regulation of information from PRRs to downstream signaling components is vital to mounting an appropriate immune response and requires dynamic interactions of these PTI components. We used transcriptome profiling, phenotypic analysis, molecular genetics, and protein-protein interaction analysis to understand the roles of the Arabidopsis plant U-box (PUB) proteins PUB2 and PUB4 in disease resistance and PTI signaling. Loss of function of both PUB2 and PUB4 diminishes the PAMP-triggered oxidative bursts and dampens mitogen-activated protein kinase signaling, resulting in a severe compromise in resistance to not only pathogenic but also nonpathogenic strains of Pseudomonas syringae. Within PUB4, the E3 ligase activity is dispensable, but the armadillo repeat region is essential and sufficient for its function in immunity. PUB2 and PUB4 interact with PTI signaling components, including FLS2, BIK1, PBL27, and RbohD, and enhance FLS2-BIK1 and BIK1-RbohD interactions. Our study reveals that PUB2 and PUB4 are critical components of plant immunity and connect PTI components to positively regulate defense responses.


Assuntos
Proteínas de Arabidopsis , Arabidopsis , Doenças das Plantas , Ubiquitina-Proteína Ligases , Arabidopsis/imunologia , Proteínas de Arabidopsis/imunologia , Doenças das Plantas/imunologia , Doenças das Plantas/microbiologia , Imunidade Vegetal , Pseudomonas syringae/fisiologia , Ubiquitina-Proteína Ligases/imunologia
13.
Carbohydr Polym ; 277: 118839, 2022 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-34893256

RESUMO

Lipopolysaccharides, the major outer membrane components of Gram-negative bacteria, are crucial actors of the host-microbial dialogue. They can contribute to the establishment of either symbiosis or bacterial virulence, depending on the bacterial lifestyle. Plant microbiota shows great complexity, promotes plant health and growth and assures protection from pathogens. How plants perceive LPS from plant-associated bacteria and discriminate between beneficial and pathogenic microbes is an open and urgent question. Here, we report on the structure, conformation, membrane properties and immune recognition of LPS isolated from the Arabidopsis thaliana root microbiota member Herbaspirillum sp. Root189. The LPS consists of an O-methylated and variously acetylated D-rhamnose containing polysaccharide with a rather hydrophobic surface. Plant immunology studies in A. thaliana demonstrate that the native acetylated O-antigen shields the LPS from immune recognition whereas the O-deacylated one does not. These findings highlight the role of Herbaspirillum LPS within plant-microbial crosstalk, and how O-antigen modifications influence membrane properties and modulate LPS host recognition.


Assuntos
Arabidopsis/química , Herbaspirillum/imunologia , Lipopolissacarídeos/imunologia , Antígenos O/imunologia , Raízes de Plantas/química , Arabidopsis/imunologia , Arabidopsis/microbiologia , Lipopolissacarídeos/química , Lipopolissacarídeos/isolamento & purificação , Antígenos O/química , Antígenos O/isolamento & purificação , Raízes de Plantas/imunologia , Raízes de Plantas/microbiologia
14.
Nature ; 598(7881): 500-503, 2021 10.
Artigo em Inglês | MEDLINE | ID: mdl-34544113

RESUMO

Plant immune responses are mainly activated by two types of receptor. Pattern recognition receptors localized on the plasma membrane perceive extracellular microbial features, and nucleotide-binding leucine-rich repeat receptors (NLRs) recognize intracellular effector proteins from pathogens1. NLRs possessing amino-terminal Toll/interleukin-1 receptor (TIR) domains activate defence responses via the NADase activity of the TIR domain2,3. Here we report that activation of TIR signalling has a key role in pattern-triggered immunity (PTI) mediated by pattern recognition receptors. TIR signalling mutants exhibit attenuated PTI responses and decreased resistance against pathogens. Consistently, PTI is compromised in plants with reduced NLR levels. Treatment with the PTI elicitor flg22 or nlp20 rapidly induces many genes encoding TIR-domain-containing proteins, which is likely to be responsible for activating TIR signalling during PTI. Overall, our study reveals that activation of TIR signalling is an important mechanism for boosting plant defence during PTI.


Assuntos
Arabidopsis/imunologia , Imunidade Vegetal , Domínios Proteicos , Receptores de Interleucina-1/química , Receptores de Reconhecimento de Padrão/imunologia , Transdução de Sinais , Receptores Toll-Like/química , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Hidrolases de Éster Carboxílico/genética , Proteínas de Ligação a DNA/genética , Proteínas Quinases/metabolismo , Proteínas Serina-Treonina Quinases/genética , Proteínas Serina-Treonina Quinases/metabolismo , Pseudomonas syringae/imunologia , Pseudomonas syringae/fisiologia , Receptores de Superfície Celular/metabolismo , Tabaco/genética , Ubiquitina-Proteína Ligases
15.
Proc Natl Acad Sci U S A ; 118(50)2021 12 14.
Artigo em Inglês | MEDLINE | ID: mdl-34880132

RESUMO

Plants use intracellular nucleotide-binding domain (NBD) and leucine-rich repeat (LRR)-containing immune receptors (NLRs) to detect pathogen-derived effector proteins. The Arabidopsis NLR pair RRS1-R/RPS4 confers disease resistance to different bacterial pathogens by perceiving the structurally distinct effectors AvrRps4 from Pseudomonas syringae pv. pisi and PopP2 from Ralstonia solanacearum via an integrated WRKY domain in RRS1-R. How the WRKY domain of RRS1 (RRS1WRKY) perceives distinct classes of effector to initiate an immune response is unknown. Here, we report the crystal structure of the in planta processed C-terminal domain of AvrRps4 (AvrRps4C) in complex with RRS1WRKY Perception of AvrRps4C by RRS1WRKY is mediated by the ß2-ß3 segment of RRS1WRKY that binds an electronegative patch on the surface of AvrRps4C Structure-based mutations that disrupt AvrRps4C-RRS1WRKY interactions in vitro compromise RRS1/RPS4-dependent immune responses. We also show that AvrRps4C can associate with the WRKY domain of the related but distinct RRS1B/RPS4B NLR pair, and the DNA-binding domain of AtWRKY41, with similar binding affinities and how effector binding interferes with WRKY-W-box DNA interactions. This work demonstrates how integrated domains in plant NLRs can directly bind structurally distinct effectors to initiate immunity.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/microbiologia , Proteínas de Bactérias/metabolismo , Proteínas de Plantas/metabolismo , Pseudomonas syringae/metabolismo , Arabidopsis/imunologia , Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Proteínas de Bactérias/genética , Morte Celular , Clonagem Molecular , DNA de Plantas , Regulação da Expressão Gênica de Plantas/imunologia , Modelos Moleculares , Mutação , Proteínas de Plantas/genética , Conformação Proteica , Pseudomonas syringae/imunologia , Tabaco
16.
Cell Rep ; 37(11): 110125, 2021 12 14.
Artigo em Inglês | MEDLINE | ID: mdl-34910911

RESUMO

Plants tailor immune responses to defend against pathogens with different lifestyles. In this process, antagonism between the immune hormones salicylic acid (SA) and jasmonic acid (JA) optimizes transcriptional signatures specifically to the attacker encountered. Antagonism is controlled by the transcription cofactor NPR1. The indispensable role of NPR1 in activating SA-responsive genes is well understood, but how it functions as a repressor of JA-responsive genes remains unclear. Here, we demonstrate that SA-induced NPR1 is recruited to JA-responsive promoter regions that are co-occupied by a JA-induced transcription complex consisting of the MYC2 activator and MED25 Mediator subunit. In the presence of SA, NPR1 physically associates with JA-induced MYC2 and inhibits transcriptional activation by disrupting its interaction with MED25. Importantly, NPR1-mediated inhibition of MYC2 is a major immune mechanism for suppressing pathogen virulence. Thus, NPR1 orchestrates the immune transcriptome not only by activating SA-responsive genes but also by acting as a corepressor of JA-responsive MYC2.


Assuntos
Aminoácidos/toxicidade , Proteínas de Arabidopsis/metabolismo , Arabidopsis/imunologia , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Indenos/toxicidade , Doenças das Plantas/imunologia , Imunidade Vegetal , Proteínas Proto-Oncogênicas c-myc/antagonistas & inibidores , Anti-Infecciosos , Arabidopsis/efeitos dos fármacos , Arabidopsis/crescimento & desenvolvimento , Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Proteínas Correpressoras , Ciclopentanos/farmacologia , Oxilipinas/farmacologia , Doenças das Plantas/microbiologia , Reguladores de Crescimento de Plantas/farmacologia , Pseudomonas syringae/química , Ácido Salicílico/farmacologia , Transdução de Sinais
17.
Plant Physiol ; 187(4): 2763-2784, 2021 12 04.
Artigo em Inglês | MEDLINE | ID: mdl-34890461

RESUMO

Jasmonic acid (JA) and ethylene (ET) signaling modulate plant defense against necrotrophic pathogens in a synergistic and interdependent manner, while JA and ET also have independent roles in certain processes, e.g. in responses to wounding and flooding, respectively. These hormone pathways lead to transcriptional reprogramming, which is a major part of plant immunity and requires the roles of transcription factors. ET response factors are responsible for the transcriptional regulation of JA/ET-responsive defense genes, of which ORA59 functions as a key regulator of this process and has been implicated in the JA-ET crosstalk. We previously demonstrated that Arabidopsis (Arabidopsis thaliana) GDSL LIPASE 1 (GLIP1) depends on ET for gene expression and pathogen resistance. Here, promoter analysis of GLIP1 revealed ERELEE4 as the critical cis-element for ET-responsive GLIP1 expression. In a yeast one-hybrid screening, ORA59 was isolated as a specific transcription factor that binds to the ERELEE4 element, in addition to the well-characterized GCC box. We found that ORA59 regulates JA/ET-responsive genes through direct binding to these elements in gene promoters. Notably, ORA59 exhibited a differential preference for GCC box and ERELEE4, depending on whether ORA59 activation is achieved by JA and ET, respectively. JA and ET induced ORA59 phosphorylation, which was required for both activity and specificity of ORA59. Furthermore, RNA-seq and virus-induced gene silencing analyses led to the identification of ORA59 target genes of distinct functional categories in JA and ET pathways. Our results provide insights into how ORA59 can generate specific patterns of gene expression dynamics through JA and ET hormone pathways.


Assuntos
Proteínas de Arabidopsis/genética , Arabidopsis/genética , Ciclopentanos/metabolismo , Etilenos/metabolismo , Oxilipinas/metabolismo , Imunidade Vegetal/genética , Fatores de Transcrição/genética , Arabidopsis/imunologia , Proteínas de Arabidopsis/metabolismo , DNA de Plantas/metabolismo , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Fatores de Transcrição/metabolismo
18.
Plant Commun ; 2(6): 100213, 2021 11 08.
Artigo em Inglês | MEDLINE | ID: mdl-34778745

RESUMO

Arabidopsis SYSTEMIC ACQUIRED RESISTANCE DEFICIENT 1 (SARD1) and CALMODULIN-BINDING PROTEIN 60g (CBP60g) are two master transcription factors that regulate many defense-related genes in plant immunity. They are required for immunity downstream of the receptor-like protein SUPPRESSOR OF NPR1-1, CONSTITUTIVE 2 (SNC2). Constitutive defense responses in the gain-of-function autoimmune snc2-1D mutant are modestly affected in either sard1 or cbp60g single mutants but completely suppressed in the sard1 cbp60g double mutant. Here we report that CBP60b, another member of the CBP60 family, also functions as a positive regulator of SNC2-mediated immunity. Loss-of-function mutations of CBP60b suppress the constitutive expression of SARD1 and enhanced disease resistance in cbp60g-1 snc2-1D, whereas overexpression of CBP60b leads to elevated SARD1 expression and constitutive defense responses. In addition, transient expression of CBP60b in Nicotiana benthamiana activates the expression of the pSARD1::luciferase reporter gene. Chromatin immunoprecipitation assays further showed that CBP60b is recruited to the promoter region of SARD1, suggesting that it directly regulates SARD1 expression. Interestingly, knocking out CBP60b in the wild-type background leads to ENHANCED DISEASE SUSCEPTIBILITY 1 (EDS1)-dependent autoimmunity, suggesting that CBP60b is required for the expression of a guardee/decoy or a negative regulator of immunity mediated by receptors carrying an N-terminal Toll-interleukin-1 receptor-like domain.


Assuntos
Arabidopsis/genética , Arabidopsis/imunologia , Proteínas de Ligação a Calmodulina/genética , Proteínas de Ligação a Calmodulina/imunologia , Resistência à Doença/genética , Resistência à Doença/imunologia , Doenças das Plantas/imunologia , Regulação da Expressão Gênica de Plantas , Genes de Plantas , Variação Genética , Genótipo , Mutação , Doenças das Plantas/genética , Ácido Salicílico/imunologia , Ácido Salicílico/metabolismo , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo
19.
Plant Commun ; 2(6): 100234, 2021 11 08.
Artigo em Inglês | MEDLINE | ID: mdl-34778748

RESUMO

Arsenic is a metalloid that is toxic to plants. Arsenate (As(V)), the prevalent chemical form of arsenic, is a phosphate (Pi) analog and is incorporated into plant cells via Pi transporters. Here, we found that the MYB40 transcription factor played important roles in the control of Arabidopsis As(V) resistance. The expression of MYB40 was induced by As(V) stress. MYB40-overexpressing lines had an obvious As(V)-resistant phenotype and a reduced As(V)/Pi uptake rate, whereas myb40 mutants were sensitive to As(V) stress. Upon exposure to As(V), MYB40 directly repressed the expression of PHT1;1, which encodes a main Pi transporter. The As(V)-resistant phenotypes of MYB40-overexpressing lines were impaired by overexpression of PHT1;1, demonstrating an epistatic genetic relationship between MYB40 and PHT1;1. Moreover, overexpression of MYB40 enhanced, and disruption of MYB40 reduced, thiol-peptide contents. Upon exposure to As(V), MYB40 positively regulated the expression of PCS1, which encodes a phytochelatin synthase, and ABCC1 and ABCC2, which encode the major vacuolar phytochelatin transporters. Together, our data demonstrate that AtMYB40 acts as a central regulator of As(V) responses, providing a genetic strategy for enhancing plant As(V) tolerance and reducing As(V) uptake to improve food safety.


Assuntos
Arabidopsis/genética , Arabidopsis/imunologia , Arsênio/toxicidade , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Genes de Plantas , Imunidade Vegetal/genética , Fatores de Transcrição/metabolismo , Variação Genética , Genótipo
20.
Int J Mol Sci ; 22(19)2021 Sep 28.
Artigo em Inglês | MEDLINE | ID: mdl-34638807

RESUMO

Calcium signals are crucial for the activation and coordination of signaling cascades leading to the establishment of plant defense mechanisms. Here, we studied the contribution of CML8, an Arabidopsis calmodulin-like protein in response to Ralstonia solanacearum and to pathogens with different lifestyles, such as Xanthomonas campestris pv. campestris and Phytophtora capsici. We used pathogenic infection assays, gene expression, RNA-seq approaches, and comparative analysis of public data on CML8 knockdown and overexpressing Arabidopsis lines to demonstrate that CML8 contributes to defense mechanisms against pathogenic bacteria and oomycetes. CML8 gene expression is finely regulated at the root level and manipulated during infection with Ralstonia, and CML8 overexpression confers better plant tolerance. To understand the processes controlled by CML8, genes differentially expressed at the root level in the first hours of infection have been identified. Overexpression of CML8 also confers better tolerance against Xanthomonas and Phytophtora, and most of the genes differentially expressed in response to Ralstonia are differentially expressed in these different pathosystems. Collectively, CML8 acts as a positive regulator against Ralstonia solanaceraum and against other vascular or root pathogens, suggesting that CML8 is a multifunctional protein that regulates common downstream processes involved in the defense response of plants to several pathogens.


Assuntos
Arabidopsis/metabolismo , Cálcio/metabolismo , Resistência à Doença , Doenças das Plantas , Transdução de Sinais , Arabidopsis/imunologia , Arabidopsis/microbiologia , Arabidopsis/fisiologia , Regulação da Expressão Gênica de Plantas , Phytophthora , Ralstonia solanacearum , Xanthomonas campestris
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