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1.
Proc Natl Acad Sci U S A ; 118(10)2021 03 09.
Artículo en Inglés | MEDLINE | ID: mdl-33649235

RESUMEN

The versatility of mitogen-activated protein kinases (MAPKs) in translating exogenous and endogenous stimuli into appropriate cellular responses depends on its substrate specificity. In animals, several mechanisms have been proposed about how MAPKs maintain specificity to regulate distinct functional pathways. However, little is known of mechanisms that enable substrate selectivity in plant MAPKs. Small ubiquitin-like modifier (SUMO), a posttranslational modification system, plays an important role in plant development and defense by rapid reprogramming of cellular events. In this study we identified a functional SUMO interaction motif (SIM) in Arabidopsis MPK3 and MPK6 that reveals a mechanism for selective interaction of MPK3/6 with SUMO-conjugated WRKY33, during defense. We show that WRKY33 is rapidly SUMOylated in response to Botrytis cinerea infection and flg22 elicitor treatment. SUMOylation mediates WRKY33 phosphorylation by MPKs and consequent transcription factor activity. Disruption of either WRKY33 SUMO or MPK3/6 SIM sites attenuates their interaction and inactivates WRKY33-mediated defense. However, MPK3/6 SIM mutants show normal interaction with a non-SUMOylated form of another transcription factor, SPEECHLESS, unraveling a role for SUMOylation in differential substrate selectivity by MPKs. We reveal that the SUMO proteases, SUMO PROTEASE RELATED TO FERTILITY1 (SPF1) and SPF2 control WRKY33 SUMOylation and demonstrate a role for these SUMO proteases in defense. Our data reveal a mechanism by which MPK3/6 prioritize molecular pathways by differentially selecting substrates using the SUMO-SIM module during defense responses.


Asunto(s)
Proteínas de Arabidopsis , Arabidopsis , Botrytis/inmunología , Quinasas de Proteína Quinasa Activadas por Mitógenos , Proteínas Quinasas Activadas por Mitógenos , Enfermedades de las Plantas , Ubiquitinas , Arabidopsis/genética , Arabidopsis/inmunología , Arabidopsis/microbiología , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/inmunología , Quinasas de Proteína Quinasa Activadas por Mitógenos/genética , Quinasas de Proteína Quinasa Activadas por Mitógenos/inmunología , Proteínas Quinasas Activadas por Mitógenos/genética , Proteínas Quinasas Activadas por Mitógenos/inmunología , Enfermedades de las Plantas/genética , Enfermedades de las Plantas/inmunología , Ubiquitinas/genética , Ubiquitinas/inmunología
2.
Plant Physiol ; 182(2): 1161-1181, 2020 02.
Artículo en Inglés | MEDLINE | ID: mdl-31659127

RESUMEN

Plants optimize their growth and survival through highly integrated regulatory networks that coordinate defensive measures and developmental transitions in response to environmental cues. Protein phosphatase 2A (PP2A) is a key signaling component that controls stress reactions and growth at different stages of plant development, and the PP2A regulatory subunit PP2A-B'γ is required for negative regulation of pathogenesis responses and for maintenance of cell homeostasis in short-day conditions. Here, we report molecular mechanisms by which PP2A-B'γ regulates Botrytis cinerea resistance and leaf senescence in Arabidopsis (Arabidopsis thaliana). We extend the molecular functionality of PP2A-B'γ to a protein kinase-phosphatase interaction with the defense-associated calcium-dependent protein kinase CPK1 and present indications this interaction may function to control CPK1 activity. In presenescent leaf tissues, PP2A-B'γ is also required to negatively control the expression of salicylic acid-related defense genes, which have recently proven vital in plant resistance to necrotrophic fungal pathogens. In addition, we find the premature leaf yellowing of pp2a-b'γ depends on salicylic acid biosynthesis via SALICYLIC ACID INDUCTION DEFICIENT2 and bears the hallmarks of developmental leaf senescence. We propose PP2A-B'γ age-dependently controls salicylic acid-related signaling in plant immunity and developmental leaf senescence.


Asunto(s)
Proteínas de Arabidopsis/metabolismo , Arabidopsis/enzimología , Botrytis/inmunología , Senescencia Celular/genética , Resistencia a la Enfermedad/genética , Enfermedades de las Plantas/inmunología , Hojas de la Planta/metabolismo , Proteína Fosfatasa 2/metabolismo , Arabidopsis/genética , Arabidopsis/crecimiento & desarrollo , Arabidopsis/microbiología , Proteínas de Arabidopsis/genética , Calcio/metabolismo , Senescencia Celular/fisiología , Cisteína Endopeptidasas/genética , Cisteína Endopeptidasas/metabolismo , Resistencia a la Enfermedad/inmunología , Regulación del Desarrollo de la Expresión Génica/genética , Regulación de la Expresión Génica de las Plantas/genética , Genotipo , Transferasas Intramoleculares/genética , Transferasas Intramoleculares/metabolismo , Mutación , Fenotipo , Enfermedades de las Plantas/genética , Enfermedades de las Plantas/microbiología , Inmunidad de la Planta/genética , Hojas de la Planta/genética , Hojas de la Planta/crecimiento & desarrollo , Unión Proteica , Proteínas Quinasas/genética , Proteínas Quinasas/metabolismo , Proteína Fosfatasa 2/genética , Ácido Salicílico/metabolismo , Transducción de Señal/genética , Factores de Transcripción/genética , Factores de Transcripción/metabolismo , Transcriptoma/genética
3.
Molecules ; 25(14)2020 Jul 08.
Artículo en Inglés | MEDLINE | ID: mdl-32650401

RESUMEN

Natural rhamnolipids are potential biocontrol agents for plant protection against bacterial and fungal diseases. In this work, we synthetized new synthetic mono-rhamnolipids (smRLs) consisting in a rhamnose connected to a simple acyl chain and differing by the nature of the link and the length of the lipid tail. We then investigated the effects of these ether, ester, carbamate or succinate smRL derivatives on Botrytis cinerea development, symptoms spreading on tomato leaves and immune responses in tomato plants. Our results demonstrate that synthetic smRLs are able to trigger early and late immunity-related plant defense responses in tomato and increase plant resistance against B. cinerea in controlled conditions. Structure-function analysis showed that chain length of the lipidic part and type of acyl chain were critical to smRLs immune activity and to the extent of symptoms caused by the fungus on tomato leaves.


Asunto(s)
Antifúngicos , Botrytis/inmunología , Glucolípidos , Enfermedades de las Plantas , Inmunidad de la Planta/efectos de los fármacos , Ramnosa/análogos & derivados , Solanum lycopersicum , Antifúngicos/síntesis química , Antifúngicos/química , Antifúngicos/farmacología , Glucolípidos/síntesis química , Glucolípidos/química , Glucolípidos/farmacología , Solanum lycopersicum/inmunología , Solanum lycopersicum/microbiología , Enfermedades de las Plantas/inmunología , Enfermedades de las Plantas/microbiología
4.
J Exp Bot ; 70(20): 5971-5984, 2019 10 24.
Artículo en Inglés | MEDLINE | ID: mdl-31328223

RESUMEN

Prevailing evidence indicates that abscisic acid (ABA) negatively influences immunity to the fungal pathogen Botrytis cinerea in most but not all cases. ABA is required for cuticle biosynthesis, and cuticle permeability enhances immunity to Botrytis via unknown mechanisms. This complex web of responses obscures the role of ABA in Botrytis immunity. Here, we addressed the relationships between ABA sensitivity, cuticle permeability, and Botrytis immunity in the Arabidopsis thaliana ABA-hypersensitive mutants protein phosphatase2c quadruple mutant (pp2c-q) and enhanced response to aba1 (era1-2). Neither pp2c-q nor era1-2 exhibited phenotypes predicted by the known roles of ABA; conversely, era1-2 had a permeable cuticle and was Botrytis resistant. We employed RNA-seq analysis in cuticle-permeable mutants of differing ABA sensitivities and identified a core set of constitutively activated genes involved in Botrytis immunity and susceptibility to biotrophs, independent of ABA signaling. Furthermore, botrytis susceptible1 (bos1), a mutant with deregulated cell death and enhanced ABA sensitivity, suppressed the Botrytis immunity of cuticle permeable mutants, and this effect was linearly correlated with the extent of spread of wound-induced cell death in bos1. Overall, our data demonstrate that Botrytis immunity conferred by cuticle permeability can be genetically uncoupled from PP2C-regulated ABA sensitivity, but requires negative regulation of a parallel ABA-dependent cell-death pathway.


Asunto(s)
Ácido Abscísico/metabolismo , Arabidopsis/metabolismo , Arabidopsis/microbiología , Botrytis/inmunología , Botrytis/patogenicidad , Arabidopsis/inmunología , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Regulación de la Expresión Génica de las Plantas , Enfermedades de las Plantas/microbiología , Transducción de Señal/fisiología
5.
Plant Cell ; 28(6): 1328-42, 2016 06.
Artículo en Inglés | MEDLINE | ID: mdl-27268428

RESUMEN

MAP kinase (MPK) cascades in Arabidopsis thaliana and other vascular plants are activated by developmental cues, abiotic stress, and pathogen infection. Much less is known of MPK functions in nonvascular land plants such as the moss Physcomitrella patens Here, we provide evidence for a signaling pathway in P. patens required for immunity triggered by pathogen associated molecular patterns (PAMPs). This pathway induces rapid growth inhibition, a novel fluorescence burst, cell wall depositions, and accumulation of defense-related transcripts. Two P. patens MPKs (MPK4a and MPK4b) are phosphorylated and activated in response to PAMPs. This activation in response to the fungal PAMP chitin requires a chitin receptor and one or more MAP kinase kinase kinases and MAP kinase kinases. Knockout lines of MPK4a appear wild type but have increased susceptibility to the pathogenic fungi Botrytis cinerea and Alternaria brassisicola Both PAMPs and osmotic stress activate some of the same MPKs in Arabidopsis. In contrast, abscisic acid treatment or osmotic stress of P. patens does not activate MPK4a or any other MPK, but activates at least one SnRK2 kinase. Signaling via MPK4a may therefore be specific to immunity, and the moss relies on other pathways to respond to osmotic stress.


Asunto(s)
Bryopsida/inmunología , Bryopsida/metabolismo , Regulación de la Expresión Génica de las Plantas/fisiología , Inmunidad Innata/fisiología , Alternaria/inmunología , Alternaria/patogenicidad , Arabidopsis/efectos de los fármacos , Arabidopsis/inmunología , Arabidopsis/metabolismo , Arabidopsis/microbiología , Botrytis/inmunología , Botrytis/patogenicidad , Bryopsida/efectos de los fármacos , Bryopsida/microbiología , Regulación de la Expresión Génica de las Plantas/efectos de los fármacos , Regulación de la Expresión Génica de las Plantas/genética , Inmunidad Innata/genética , Presión Osmótica/efectos de los fármacos , Moléculas de Patrón Molecular Asociado a Patógenos/farmacología , Fosforilación/efectos de los fármacos , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo
6.
PLoS Pathog ; 12(3): e1005518, 2016 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-27007252

RESUMEN

Damage-associated molecular pattern molecules (DAMPs) signal the presence of tissue damage to induce immune responses in plants and animals. Here, we report that High Mobility Group Box 3 (HMGB3) is a novel plant DAMP. Extracellular HMGB3, through receptor-like kinases BAK1 and BKK1, induced hallmark innate immune responses, including i) MAPK activation, ii) defense-related gene expression, iii) callose deposition, and iv) enhanced resistance to Botrytis cinerea. Infection by necrotrophic B. cinerea released HMGB3 into the extracellular space (apoplast). Silencing HMGBs enhanced susceptibility to B. cinerea, while HMGB3 injection into apoplast restored resistance. Like its human counterpart, HMGB3 binds salicylic acid (SA), which results in inhibition of its DAMP activity. An SA-binding site mutant of HMGB3 retained its DAMP activity, which was no longer inhibited by SA, consistent with its reduced SA-binding activity. These results provide cross-kingdom evidence that HMGB proteins function as DAMPs and that SA is their conserved inhibitor.


Asunto(s)
Botrytis/inmunología , Regulación de la Expresión Génica de las Plantas , Oxilipinas/metabolismo , Enfermedades de las Plantas/parasitología , Plantas/inmunología , Ácido Salicílico/metabolismo , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Botrytis/metabolismo , Ciclopentanos/metabolismo , Resistencia a la Enfermedad , Etilenos/metabolismo , Hojas de la Planta/genética , Pseudomonas syringae/metabolismo , Transducción de Señal/efectos de los fármacos
7.
Proc Natl Acad Sci U S A ; 112(17): 5533-8, 2015 Apr 28.
Artículo en Inglés | MEDLINE | ID: mdl-25870275

RESUMEN

Oligogalacturonides (OGs) are fragments of pectin that activate plant innate immunity by functioning as damage-associated molecular patterns (DAMPs). We set out to test the hypothesis that OGs are generated in planta by partial inhibition of pathogen-encoded polygalacturonases (PGs). A gene encoding a fungal PG was fused with a gene encoding a plant polygalacturonase-inhibiting protein (PGIP) and expressed in transgenic Arabidopsis plants. We show that expression of the PGIP-PG chimera results in the in vivo production of OGs that can be detected by mass spectrometric analysis. Transgenic plants expressing the chimera under control of a pathogen-inducible promoter are more resistant to the phytopathogens Botrytis cinerea, Pectobacterium carotovorum, and Pseudomonas syringae. These data provide strong evidence for the hypothesis that OGs released in vivo act as a DAMP signal to trigger plant immunity and suggest that controlled release of these molecules upon infection may be a valuable tool to protect plants against infectious diseases. On the other hand, elevated levels of expression of the chimera cause the accumulation of salicylic acid, reduced growth, and eventually lead to plant death, consistent with the current notion that trade-off occurs between growth and defense.


Asunto(s)
Proteínas de Arabidopsis/biosíntesis , Arabidopsis/metabolismo , Proteínas Fúngicas/biosíntesis , Ácidos Hexurónicos/metabolismo , Enfermedades de las Plantas/inmunología , Inmunidad de la Planta , Proteínas de Plantas/biosíntesis , Poligalacturonasa/biosíntesis , Animales , Arabidopsis/genética , Arabidopsis/inmunología , Arabidopsis/microbiología , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/inmunología , Botrytis/crecimiento & desarrollo , Botrytis/inmunología , Proteínas Fúngicas/genética , Proteínas Fúngicas/inmunología , Ácidos Hexurónicos/inmunología , Ratones Transgénicos , Pectobacterium carotovorum/crecimiento & desarrollo , Pectobacterium carotovorum/inmunología , Enfermedades de las Plantas/genética , Enfermedades de las Plantas/microbiología , Proteínas de Plantas/genética , Proteínas de Plantas/inmunología , Poligalacturonasa/genética , Poligalacturonasa/inmunología , Pseudomonas syringae/crecimiento & desarrollo , Pseudomonas syringae/inmunología , Proteínas Recombinantes de Fusión/biosíntesis , Proteínas Recombinantes de Fusión/genética , Proteínas Recombinantes de Fusión/inmunología
8.
Plant Physiol ; 172(2): 1293-1305, 2016 10.
Artículo en Inglés | MEDLINE | ID: mdl-27591188

RESUMEN

Pathogen-responsive mitogen-activated protein kinase (MAPK or MPK) cascades relay signals from activated immune receptors across the nuclear envelope to intranuclear targets. However, in plants, little is known about the spatial control of MAPK signaling. Here, we report that the Arabidopsis (Arabidopsis thaliana) nuclear pore complex protein Nup88/MOS7 is essential for immunity to the necrotrophic fungus Botrytis cinerea The mos7-1 mutation, causing a four-amino acid deletion, compromises B. cinerea-induced activation of the key immunoregulatory MAPKs MPK3/MPK6 and reduces MPK3 protein levels posttranscriptionally. Furthermore, MOS7 contributes to retaining a sufficient MPK3 abundance in the nucleus, which is required for full immunity to B. cinerea Finally, we present a structural model of MOS7 and show that the mos7-1 mutation compromises interactions with Nup98a/b, two phenylalanine-glycine repeat nucleoporins implicated in maintaining the selective nuclear pore complex permeability barrier. Together, our analysis uncovered MOS7 and Nup98 as novel components of plant immunity toward a necrotrophic pathogen and provides mechanistic insights into how these nucleoporins coordinate nucleocytoplasmic transport to mount a robust immune response.


Asunto(s)
Arabidopsis/genética , Sistema de Señalización de MAP Quinasas/genética , Proteínas de Complejo Poro Nuclear/genética , Enfermedades de las Plantas/genética , Transporte Activo de Núcleo Celular/genética , Arabidopsis/microbiología , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Botrytis/inmunología , Botrytis/fisiología , Resistencia a la Enfermedad/genética , Resistencia a la Enfermedad/inmunología , Regulación de la Expresión Génica de las Plantas , Interacciones Huésped-Patógeno/inmunología , Immunoblotting , Microscopía Confocal , Quinasas de Proteína Quinasa Activadas por Mitógenos/genética , Quinasas de Proteína Quinasa Activadas por Mitógenos/metabolismo , Proteínas Quinasas Activadas por Mitógenos/genética , Proteínas Quinasas Activadas por Mitógenos/metabolismo , Proteínas de Complejo Poro Nuclear/metabolismo , Enfermedades de las Plantas/microbiología , Inmunidad de la Planta/genética , Plantas Modificadas Genéticamente , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa
9.
Plant Cell ; 26(8): 3449-67, 2014 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-25149397

RESUMEN

Arabidopsis thaliana plants that lack ceramide kinase, encoded by ACCELERATED CELL DEATH5 (ACD5), display spontaneous programmed cell death late in development and accumulate substrates of ACD5. Here, we compared ceramide accumulation kinetics, defense responses, ultrastructural features, and sites of reactive oxygen species (ROS) production in wild-type and acd5 plants during development and/or Botrytis cinerea infection. Quantitative sphingolipid profiling indicated that ceramide accumulation in acd5 paralleled the appearance of spontaneous cell death, and it was accompanied by autophagy and mitochondrial ROS accumulation. Plants lacking ACD5 differed significantly from the wild type in their responses to B. cinerea, showing earlier and higher increases in ceramides, greater disease, smaller cell wall appositions (papillae), reduced callose deposition and apoplastic ROS, and increased mitochondrial ROS. Together, these data show that ceramide kinase greatly affects sphingolipid metabolism and the site of ROS accumulation during development and infection, which likely explains the developmental and infection-related cell death phenotypes. The acd5 plants also showed an early defect in restricting B. cinerea germination and growth, which occurred prior to the onset of cell death. This early defect in B. cinerea restriction in acd5 points to a role for ceramide phosphate and/or the balance of ceramides in mediating early antifungal responses that are independent of cell death.


Asunto(s)
Proteínas de Arabidopsis/fisiología , Arabidopsis/metabolismo , Ceramidas/biosíntesis , Peróxido de Hidrógeno/metabolismo , Mitocondrias/metabolismo , Fosfotransferasas (Aceptor de Grupo Alcohol)/fisiología , Apoptosis/genética , Arabidopsis/genética , Arabidopsis/inmunología , Arabidopsis/microbiología , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Autofagia , Botrytis/inmunología , Botrytis/fisiología , Cinética , Fosfotransferasas (Aceptor de Grupo Alcohol)/genética , Fosfotransferasas (Aceptor de Grupo Alcohol)/metabolismo , Especies Reactivas de Oxígeno/metabolismo
10.
Plant Cell ; 26(10): 4149-70, 2014 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-25281690

RESUMEN

CYCLIN-DEPENDENT KINASE8 (CDK8) is a widely studied component of eukaryotic Mediator complexes. However, the biological and molecular functions of plant CDK8 are not well understood. Here, we provide evidence for regulatory functions of Arabidopsis thaliana CDK8 in defense and demonstrate its functional and molecular interactions with other Mediator and non-Mediator subunits. The cdk8 mutant exhibits enhanced resistance to Botrytis cinerea but susceptibility to Alternaria brassicicola. The contributions of CDK8 to the transcriptional activation of defensin gene PDF1.2 and its interaction with MEDIATOR COMPLEX SUBUNIT25 (MED25) implicate CDK8 in jasmonate-mediated defense. Moreover, CDK8 associates with the promoter of AGMATINE COUMAROYLTRANSFERASE to promote its transcription and regulate the biosynthesis of the defense-active secondary metabolites hydroxycinnamic acid amides. CDK8 also interacts with the transcription factor WAX INDUCER1, implying its additional role in cuticle development. In addition, overlapping functions of CDK8 with MED12 and MED13 and interactions between CDK8 and C-type cyclins suggest the conserved configuration of the plant Mediator kinase module. In summary, while CDK8's positive transcriptional regulation of target genes and its phosphorylation activities underpin its defense functions, the impaired defense responses in the mutant are masked by its altered cuticle, resulting in specific resistance to B. cinerea.


Asunto(s)
Proteínas de Arabidopsis/genética , Arabidopsis/genética , Quinasa 8 Dependiente de Ciclina/genética , Enfermedades de las Plantas/genética , Inmunidad de la Planta/genética , Aciltransferasas/genética , Aciltransferasas/metabolismo , Alternaria/inmunología , Alternaria/fisiología , Amidas/metabolismo , Secuencia de Aminoácidos , Arabidopsis/enzimología , Arabidopsis/microbiología , Proteínas de Arabidopsis/metabolismo , Botrytis/inmunología , Botrytis/fisiología , Ácidos Cumáricos/metabolismo , Ciclina C/genética , Ciclina C/metabolismo , Quinasa 8 Dependiente de Ciclina/metabolismo , Proteínas de Unión al ADN , Perfilación de la Expresión Génica , Interacciones Huésped-Patógeno , Datos de Secuencia Molecular , Mutación , Proteínas Nucleares/genética , Proteínas Nucleares/metabolismo , Enfermedades de las Plantas/microbiología , Inmunidad de la Planta/inmunología , Plantas Modificadas Genéticamente , Regiones Promotoras Genéticas/genética , Unión Proteica , Proteínas Represoras/genética , Proteínas Represoras/metabolismo , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Homología de Secuencia de Aminoácido , Activación Transcripcional
11.
Biotechnol Lett ; 39(7): 1049-1058, 2017 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-28365881

RESUMEN

OBJECTIVES: To engineer broad spectrum resistance in potato using different expression strategies. RESULTS: The previously identified Ribosome-Inactivating Protein from Phytolacca heterotepala was expressed in potato under a constitutive or a wound-inducible promoter. Leaves and tubers of the plants constitutively expressing the transgene were resistant to Botrytis cinerea and Rhizoctonia solani, respectively. The wound-inducible promoter was useful in driving the expression upon wounding and fungal damage, and conferred resistance to B. cinerea. The observed differences between the expression strategies are discussed considering the benefits and features offered by the two systems. CONCLUSIONS: Evidence is provided of the possible impact of promoter sequences to engineer BSR in plants, highlighting that the selection of a suitable expression strategy has to balance specific needs and target species.


Asunto(s)
Resistencia a la Enfermedad , Expresión Génica , Organismos Modificados Genéticamente/inmunología , Enfermedades de las Plantas/prevención & control , Proteínas Recombinantes/metabolismo , Proteínas Inactivadoras de Ribosomas/metabolismo , Solanum tuberosum/inmunología , Botrytis/inmunología , Botrytis/patogenicidad , Regulación de la Expresión Génica de las Plantas , Organismos Modificados Genéticamente/genética , Phytolacca/enzimología , Phytolacca/genética , Enfermedades de las Plantas/microbiología , Proteínas Recombinantes/genética , Rhizoctonia/inmunología , Rhizoctonia/patogenicidad , Proteínas Inactivadoras de Ribosomas/genética , Solanum tuberosum/genética
12.
PLoS Genet ; 8(6): e1002767, 2012 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-22761583

RESUMEN

Plants under pathogen attack produce high levels of ethylene, which plays important roles in plant immunity. Previously, we reported the involvement of ACS2 and ACS6, two Type I ACS isoforms, in Botrytis cinerea-induced ethylene biosynthesis and their regulation at the protein stability level by MPK3 and MPK6, two Arabidopsis pathogen-responsive mitogen-activated protein kinases (MAPKs). The residual ethylene induction in the acs2/acs6 double mutant suggests the involvement of additional ACS isoforms. It is also known that a subset of ACS genes, including ACS6, is transcriptionally induced in plants under stress or pathogen attack. However, the importance of ACS gene activation and the regulatory mechanism(s) are not clear. In this report, we demonstrate using genetic analysis that ACS7 and ACS11, two Type III ACS isoforms, and ACS8, a Type II ACS isoform, also contribute to the B. cinerea-induced ethylene production. In addition to post-translational regulation, transcriptional activation of the ACS genes also plays a critical role in sustaining high levels of ethylene induction. Interestingly, MPK3 and MPK6 not only control the stability of ACS2 and ACS6 proteins via direct protein phosphorylation but also regulate the expression of ACS2 and ACS6 genes. WRKY33, another MPK3/MPK6 substrate, is involved in the MPK3/MPK6-induced ACS2/ACS6 gene expression based on genetic analyses. Furthermore, chromatin-immunoprecipitation assay reveals the direct binding of WRKY33 to the W-boxes in the promoters of ACS2 and ACS6 genes in vivo, suggesting that WRKY33 is directly involved in the activation of ACS2 and ACS6 expression downstream of MPK3/MPK6 cascade in response to pathogen invasion. Regulation of ACS activity by MPK3/MPK6 at both transcriptional and protein stability levels plays a key role in determining the kinetics and magnitude of ethylene induction.


Asunto(s)
Proteínas de Arabidopsis , Arabidopsis , Liasas , Quinasas de Proteína Quinasa Activadas por Mitógenos , Proteínas Quinasas Activadas por Mitógenos , Factores de Transcripción , Arabidopsis/genética , Arabidopsis/metabolismo , Arabidopsis/fisiología , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Botrytis/inmunología , Botrytis/patogenicidad , Etilenos/biosíntesis , Etilenos/metabolismo , Regulación de la Expresión Génica de las Plantas , Interacciones Huésped-Patógeno/genética , Interacciones Huésped-Patógeno/inmunología , Liasas/genética , Liasas/metabolismo , Quinasas de Proteína Quinasa Activadas por Mitógenos/genética , Quinasas de Proteína Quinasa Activadas por Mitógenos/metabolismo , Proteínas Quinasas Activadas por Mitógenos/genética , Proteínas Quinasas Activadas por Mitógenos/metabolismo , Mutación , Inmunidad de la Planta/genética , Plantas Modificadas Genéticamente , Isoformas de Proteínas , Transducción de Señal , Factores de Transcripción/genética , Factores de Transcripción/metabolismo
13.
Plant J ; 74(3): 498-510, 2013 May.
Artículo en Inglés | MEDLINE | ID: mdl-23398119

RESUMEN

Programmed cell death (PCD) in plants plays a key role in defense response and is promoted by the release of compartmentalized proteases to the cytoplasm. Yet the exact identity and control of these proteases is poorly understood. Serpins are an important group of proteins that uniquely curb the activity of proteases by irreversible inhibition; however, their role in plants remains obscure. Here we show that during cell death the Arabidopsis serpin protease inhibitor, AtSerpin1, exhibits a pro-survival function by inhibiting its target pro-death protease, RD21. AtSerpin1 accumulates in the cytoplasm and RD21 accumulates in the vacuole and in endoplasmic reticulum bodies. Elicitors of cell death, including the salicylic acid agonist benzothiadiazole and the fungal toxin oxalic acid, stimulated changes in vacuole permeability as measured by the changes in the distribution of marker dye. Concomitantly, a covalent AtSerpin1-RD21 complex was detected indicative of a change in protease compartmentalization. Furthermore, mutant plants lacking RD21 or plants with AtSerpin1 over-expression exhibited significantly less elicitor-stimulated PCD than plants lacking AtSerpin1. The necrotrophic fungi Botrytis cinerea and Sclerotina sclerotiorum secrete oxalic acid as a toxin that stimulates cell death. Consistent with a pro-death function for RD21 protease, the growth of these necrotrophs was compromised in plants lacking RD21 but accelerated in plants lacking AtSerpin1. The results indicate that AtSerpin1 controls the pro-death function of compartmentalized protease RD21 by determining a set-point for its activity and limiting the damage induced during cell death.


Asunto(s)
Proteínas de Arabidopsis/metabolismo , Arabidopsis/enzimología , Proteasas de Cisteína/metabolismo , Serpinas/metabolismo , Arabidopsis/efectos de los fármacos , Arabidopsis/genética , Arabidopsis/microbiología , Proteínas de Arabidopsis/genética , Botrytis/inmunología , Botrytis/patogenicidad , Muerte Celular , Membrana Celular/enzimología , Membrana Celular/genética , Proteasas de Cisteína/genética , Retículo Endoplásmico/metabolismo , Activación Enzimática , Interacciones Huésped-Patógeno , Complejos Multiproteicos/metabolismo , Ácido Oxálico/metabolismo , Ácido Oxálico/farmacología , Enfermedades de las Plantas/microbiología , Inmunidad de la Planta , Hojas de la Planta/efectos de los fármacos , Hojas de la Planta/microbiología , Serpinas/genética , Tiadiazoles/farmacología , Vacuolas/metabolismo
14.
Mol Plant Microbe Interact ; 27(7): 688-99, 2014 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-24678833

RESUMEN

Vitamin B6 (VB6), an essential cofactor for numerous metabolic enzymes, has recently been shown to act as a potent antioxidant and play important roles in developmental processes and stress responses. However, little is known about the possible function of VB6 in plant disease resistance response against pathogen infection. In the present study, we explored the possible involvement of VB6 in defense response against Botrytis cinerea through functional analysis of tomato VB6 biosynthetic genes. Three de novo VB6 biosynthetic genes (SlPDX1.2, SlPDX1.3, and SlPDX2) and one salvage pathway gene (SlSOS4) were identified and the SlPDX1.2, SlPDX1.3, and SlPDX2 genes were shown to encode functional enzymes involved in de novo biosynthesis of VB6, as revealed by complementation of the VB6 prototrophy in yeast snz1 and sno1 mutants. Expression of SlPDX1.2, SlPDX1.3, and SlSOS4 genes was induced by infection with B. cinerea. Virus-induced gene silencing-mediated knockdown of SlPDX1.2 or SlPDX1.3 but not SlPDX2 and SlSOS4 led to increased severity of disease caused by B. cinerea, indicating that the VB6 de novo biosynthetic pathway but not the salvage pathway is involved in tomato defense response against B. cinerea. Furthermore, the SlPDX1.2- and SlPDX1.3-silenced tomato plants exhibited reduced levels of VB6 contents and reactive oxygen species scavenging capability, increased levels of superoxide anion and H2O2 generation, and increased activity of superoxide dismutase after infection by B. cinerea. Our results suggest that VB6 and its de novo biosynthetic pathway play important roles in regulation of defense response against B. cinerea through modulating cellular antioxidant capacity.


Asunto(s)
Botrytis/inmunología , Enfermedades de las Plantas/microbiología , Solanum lycopersicum/metabolismo , Vitamina B 6/biosíntesis , Agrobacterium , Eliminación de Gen , Regulación de la Expresión Génica de las Plantas , Enfermedades de las Plantas/inmunología , Hojas de la Planta , Especies Reactivas de Oxígeno , Simbiosis , Factor de Transferencia
15.
Plant Mol Biol ; 85(4-5): 473-84, 2014 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-24817131

RESUMEN

Botrytis cinerea is the causing agent of the grey mold disease in more than 200 crop species. While signaling pathways leading to the basal resistance against this fungus are well described, the role of the import of sugars into host cells remains to be investigated. In Arabidopsis thaliana, apoplastic hexose retrieval is mediated by the activity of sugar transport proteins (STPs). Expression analysis of the 14 STP genes revealed that only STP13 was induced in leaves challenged with B. cinerea. STP13-modified plants were produced and assayed for their resistance to B. cinerea and glucose transport activity. We report that STP13-deficient plants exhibited an enhanced susceptibility and a reduced rate of glucose uptake. Conversely, plants with a high constitutive level of STP13 protein displayed an improved capacity to absorb glucose and an enhanced resistance phenotype. The correlation between STP13 transcripts, protein accumulation, glucose uptake rate and resistance level indicates that STP13 contributes to the basal resistance to B. cinerea by limiting symptom development and points out the importance of the host intracellular sugar uptake in this process. We postulate that STP13 would participate in the active resorption of hexoses to support the increased energy demand to trigger plant defense reactions and to deprive the fungus by changing sugar fluxes toward host cells.


Asunto(s)
Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Botrytis/fisiología , Regulación de la Expresión Génica de las Plantas/fisiología , Glucosa/metabolismo , Simportadores/metabolismo , Arabidopsis/genética , Arabidopsis/inmunología , Proteínas de Arabidopsis/genética , Transporte Biológico , Botrytis/inmunología , Resistencia a la Enfermedad , Predisposición Genética a la Enfermedad , Mutación , Enfermedades de las Plantas/genética , Simportadores/genética
16.
Plant Cell ; 23(10): 3824-41, 2011 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-21990940

RESUMEN

Necrotrophic pathogens are important plant pathogens that cause many devastating plant diseases. Despite their impact, our understanding of the plant defense response to necrotrophic pathogens is limited. The WRKY33 transcription factor is important for plant resistance to necrotrophic pathogens; therefore, elucidation of its functions will enhance our understanding of plant immunity to necrotrophic pathogens. Here, we report the identification of two WRKY33-interacting proteins, nuclear-encoded SIGMA FACTOR BINDING PROTEIN1 (SIB1) and SIB2, which also interact with plastid-encoded plastid RNA polymerase SIGMA FACTOR1. Both SIB1 and SIB2 contain an N-terminal chloroplast targeting signal and a putative nuclear localization signal, suggesting that they are dual targeted. Bimolecular fluorescence complementation indicates that WRKY33 interacts with SIBs in the nucleus of plant cells. Both SIB1 and SIB2 contain a short VQ motif that is important for interaction with WRKY33. The two VQ motif-containing proteins recognize the C-terminal WRKY domain and stimulate the DNA binding activity of WRKY33. Like WRKY33, both SIB1 and SIB2 are rapidly and strongly induced by the necrotrophic pathogen Botrytis cinerea. Resistance to B. cinerea is compromised in the sib1 and sib2 mutants but enhanced in SIB1-overexpressing transgenic plants. These results suggest that dual-targeted SIB1 and SIB2 function as activators of WRKY33 in plant defense against necrotrophic pathogens.


Asunto(s)
Proteínas de Arabidopsis/metabolismo , Arabidopsis/genética , Arabidopsis/inmunología , Botrytis/patogenicidad , Enfermedades de las Plantas/inmunología , Secuencia de Aminoácidos , Arabidopsis/fisiología , Proteínas de Arabidopsis/genética , Botrytis/inmunología , Proteínas Portadoras/genética , Proteínas Portadoras/metabolismo , Núcleo Celular/metabolismo , Sistema Enzimático del Citocromo P-450/genética , Sistema Enzimático del Citocromo P-450/metabolismo , ADN de Plantas/genética , Regulación de la Expresión Génica de las Plantas , Silenciador del Gen , Datos de Secuencia Molecular , Mutagénesis Insercional , Enfermedades de las Plantas/microbiología , Plantas Modificadas Genéticamente , Mapeo de Interacción de Proteínas , Estructura Terciaria de Proteína , Proteínas Recombinantes de Fusión , Alineación de Secuencia , Factor sigma/genética , Factor sigma/metabolismo , Factores de Transcripción/genética , Factores de Transcripción/metabolismo
17.
Plant Cell ; 23(8): 2831-49, 2011 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-21862710

RESUMEN

Arabidopsis thaliana BOTRYTIS-INDUCED KINASE1 (BIK1) regulates immune responses to a distinct class of pathogens. Here, mechanisms underlying BIK1 function and its interactions with other immune response regulators were determined. We describe BIK1 function as a component of ethylene (ET) signaling and PAMP-triggered immunity (PTI) to fungal pathogens. BIK1 in vivo kinase activity increases in response to flagellin peptide (flg22) and the ET precursor 1-aminocyclopropane-1-carboxylic acid (ACC) but is blocked by inhibition of ET perception. BIK1 induction by flg22, ACC, and pathogens is strictly dependent on EIN3, and the bik1 mutation results in altered expression of ET-regulated genes. BIK1 site-directed mutants were used to determine residues essential for phosphorylation and biological functions in planta, including PTI, ET signaling, and plant growth. Genetic analysis revealed flg22-induced PTI to Botrytis cinerea requires BIK1, EIN2, and HUB1 but not genes involved in salicylate (SA) functions. BIK1-mediated PTI to Pseudomonas syringae is modulated by SA, ET, and jasmonate signaling. The coi1 mutation suppressed several bik1 phenotypes, suggesting that COI1 may act as a repressor of BIK1 function. Thus, common and distinct mechanisms underlying BIK1 function in mediating responses to distinct pathogens are uncovered. In sum, the critical role of BIK1 in plant immune responses hinges upon phosphorylation, its function in ET signaling, and complex interactions with other immune response regulators.


Asunto(s)
Proteínas de Arabidopsis/metabolismo , Arabidopsis/inmunología , Etilenos/metabolismo , Inmunidad de la Planta , Proteínas Serina-Treonina Quinasas/metabolismo , Transducción de Señal/fisiología , Secuencia de Aminoácidos , Aminoácidos Cíclicos/farmacología , Arabidopsis/enzimología , Arabidopsis/genética , Arabidopsis/microbiología , Proteínas de Arabidopsis/química , Proteínas de Arabidopsis/genética , Botrytis/inmunología , Botrytis/fisiología , Secuencia Conservada , Ciclopentanos/metabolismo , Flagelina/farmacología , Regulación de la Expresión Génica de las Plantas , Hipocótilo/enzimología , Hipocótilo/genética , Hipocótilo/inmunología , Hipocótilo/fisiología , Datos de Secuencia Molecular , Mutación , Oxilipinas/metabolismo , Fenotipo , Fosforilación , Enfermedades de las Plantas/inmunología , Enfermedades de las Plantas/microbiología , Reguladores del Crecimiento de las Plantas/metabolismo , Plantas Modificadas Genéticamente/enzimología , Plantas Modificadas Genéticamente/genética , Plantas Modificadas Genéticamente/inmunología , Plantas Modificadas Genéticamente/fisiología , Proteínas Serina-Treonina Quinasas/química , Proteínas Serina-Treonina Quinasas/genética , Pseudomonas syringae/fisiología , Ácido Salicílico/metabolismo , Plantones/enzimología , Plantones/genética , Plantones/inmunología , Plantones/fisiología
18.
PLoS Pathog ; 7(7): e1002148, 2011 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-21829351

RESUMEN

Wounded leaves of Arabidopsis thaliana show transient immunity to Botrytis cinerea, the causal agent of grey mould. Using a fluorescent probe, histological staining and a luminol assay, we now show that reactive oxygen species (ROS), including H(2)O(2) and O(2) (-), are produced within minutes after wounding. ROS are formed in the absence of the enzymes Atrboh D and F and can be prevented by diphenylene iodonium (DPI) or catalase. H(2)O(2) was shown to protect plants upon exogenous application. ROS accumulation and resistance to B. cinerea were abolished when wounded leaves were incubated under dry conditions, an effect that was found to depend on abscisic acid (ABA). Accordingly, ABA biosynthesis mutants (aba2 and aba3) were still fully resistant under dry conditions even without wounding. Under dry conditions, wounded plants contained higher ABA levels and displayed enhanced expression of ABA-dependent and ABA-reporter genes. Mutants impaired in cutin synthesis such as bdg and lacs2.3 are already known to display a high level of resistance to B. cinerea and were found to produce ROS even when leaves were not wounded. An increased permeability of the cuticle and enhanced ROS production were detected in aba2 and aba3 mutants as described for bdg and lacs2.3. Moreover, leaf surfaces treated with cutinase produced ROS and became more protected to B. cinerea. Thus, increased permeability of the cuticle is strongly linked with ROS formation and resistance to B. cinerea. The amount of oxalic acid, an inhibitor of ROS secreted by B. cinerea could be reduced using plants over expressing a fungal oxalate decarboxylase of Trametes versicolor. Infection of such plants resulted in a faster ROS accumulation and resistance to B. cinerea than that observed in untransformed controls, demonstrating the importance of fungal suppression of ROS formation by oxalic acid. Thus, changes in the diffusive properties of the cuticle are linked with the induction ROS and attending innate defenses.


Asunto(s)
Arabidopsis , Botrytis/inmunología , Peróxido de Hidrógeno/inmunología , Enfermedades de las Plantas , Inmunidad de la Planta/fisiología , Hojas de la Planta , Superóxidos/inmunología , Ácido Abscísico/genética , Ácido Abscísico/inmunología , Arabidopsis/inmunología , Arabidopsis/microbiología , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/inmunología , Carboxiliasas/genética , Carboxiliasas/inmunología , Coenzima A Ligasas/genética , Coenzima A Ligasas/inmunología , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Lípidos de la Membrana/genética , Lípidos de la Membrana/inmunología , Mutación/inmunología , Enfermedades de las Plantas/genética , Enfermedades de las Plantas/inmunología , Enfermedades de las Plantas/microbiología , Hojas de la Planta/genética , Hojas de la Planta/inmunología , Hojas de la Planta/microbiología , Plantas Modificadas Genéticamente/genética , Plantas Modificadas Genéticamente/inmunología , Plantas Modificadas Genéticamente/microbiología , Trametes/genética
19.
Plant Physiol ; 159(1): 239-50, 2012 May.
Artículo en Inglés | MEDLINE | ID: mdl-22383540

RESUMEN

The components in plant signal transduction pathways are intertwined and affect each other to coordinate plant growth, development, and defenses to stresses. The role of ubiquitination in connecting these pathways, particularly plant innate immunity and flowering, is largely unknown. Here, we report the dual roles for the Arabidopsis (Arabidopsis thaliana) Plant U-box protein13 (PUB13) in defense and flowering time control. In vitro ubiquitination assays indicated that PUB13 is an active E3 ubiquitin ligase and that the intact U-box domain is required for the E3 ligase activity. Disruption of the PUB13 gene by T-DNA insertion results in spontaneous cell death, the accumulation of hydrogen peroxide and salicylic acid (SA), and elevated resistance to biotrophic pathogens but increased susceptibility to necrotrophic pathogens. The cell death, hydrogen peroxide accumulation, and resistance to necrotrophic pathogens in pub13 are enhanced when plants are pretreated with high humidity. Importantly, pub13 also shows early flowering under middle- and long-day conditions, in which the expression of SUPPRESSOR OF OVEREXPRESSION OF CONSTANS1 and FLOWERING LOCUS T is induced while FLOWERING LOCUS C expression is suppressed. Finally, we found that two components involved in the SA-mediated signaling pathway, SID2 and PAD4, are required for the defense and flowering-time phenotypes caused by the loss of function of PUB13. Taken together, our data demonstrate that PUB13 acts as an important node connecting SA-dependent defense signaling and flowering time regulation in Arabidopsis.


Asunto(s)
Proteínas de Arabidopsis/metabolismo , Arabidopsis/fisiología , Flores/fisiología , Ubiquitina-Proteína Ligasas/metabolismo , Arabidopsis/enzimología , Arabidopsis/genética , Arabidopsis/microbiología , Proteínas de Arabidopsis/genética , Botrytis/inmunología , Botrytis/patogenicidad , Hidrolasas de Éster Carboxílico/genética , Hidrolasas de Éster Carboxílico/metabolismo , Muerte Celular , Clonación Molecular , Activación Enzimática , Pruebas de Enzimas , Flores/metabolismo , Regulación de la Expresión Génica de las Plantas , Genes de Plantas , Humedad , Peróxido de Hidrógeno/metabolismo , Proteínas de Dominio MADS/genética , Proteínas de Dominio MADS/metabolismo , Enfermedades de las Plantas/inmunología , Enfermedades de las Plantas/microbiología , Inmunidad de la Planta , Plantas Modificadas Genéticamente/enzimología , Plantas Modificadas Genéticamente/genética , Plantas Modificadas Genéticamente/microbiología , Plantas Modificadas Genéticamente/fisiología , Estructura Terciaria de Proteína , Pseudomonas/patogenicidad , Salicilatos/metabolismo , Factores de Tiempo , Ubiquitina-Proteína Ligasas/genética , Ubiquitinación
20.
Plant J ; 66(6): 953-68, 2011 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-21395886

RESUMEN

Autophagy is a pathway for degradation of cytoplasmic components. In plants, autophagy plays an important role in nutrient recycling during nitrogen or carbon starvation, and in responses to abiotic stress. Autophagy also regulates age- and immunity-related programmed cell death, which is important in plant defense against biotrophic pathogens. Here we show that autophagy plays a critical role in plant resistance to necrotrophic pathogens. ATG18a, a critical autophagy protein in Arabidopsis, interacts with WRKY33, a transcription factor that is required for resistance to necrotrophic pathogens. Expression of autophagy genes and formation of autophagosomes are induced in Arabidopsis by the necrotrophic fungal pathogen Botrytis cinerea. Induction of ATG18a and autophagy by B. cinerea was compromised in the wrky33 mutant, which is highly susceptible to necrotrophic pathogens. Arabidopsis mutants defective in autophagy exhibit enhanced susceptibility to the necrotrophic fungal pathogens B. cinerea and Alternaria brassicicola based on increased pathogen growth in the mutants. The hypersusceptibility of the autophagy mutants was associated with reduced expression of the jasmonate-regulated PFD1.2 gene, accelerated development of senescence-like chlorotic symptoms, and increased protein degradation in infected plant tissues. These results strongly suggest that autophagy cooperates with jasmonate- and WRKY33-mediated signaling pathways in the regulation of plant defense responses to necrotrophic pathogens.


Asunto(s)
Arabidopsis/microbiología , Autofagia , Inmunidad Innata , Enfermedades de las Plantas/microbiología , Arabidopsis/genética , Arabidopsis/inmunología , Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Proteínas Relacionadas con la Autofagia , Sitios de Unión , Botrytis/inmunología , Botrytis/patogenicidad , Ciclopentanos/metabolismo , Susceptibilidad a Enfermedades/microbiología , Fluorescencia , Perfilación de la Expresión Génica , Regulación de la Expresión Génica de las Plantas , Genes Reporteros , Oxilipinas/metabolismo , Enfermedades de las Plantas/inmunología , Hojas de la Planta/metabolismo , Plantas Modificadas Genéticamente/genética , Plantas Modificadas Genéticamente/inmunología , Plantas Modificadas Genéticamente/metabolismo , Plantas Modificadas Genéticamente/microbiología , Regiones Promotoras Genéticas , Proteínas Recombinantes de Fusión/metabolismo , Transducción de Señal , Factores de Transcripción/genética , Factores de Transcripción/metabolismo , Técnicas del Sistema de Dos Híbridos
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