RESUMO
Extracellular ATP (eATP) is a key signaling molecule that plays a pivotal role in plant growth and defense responses. The receptor P2K1 is responsible for perceiving eATP and initiating its signaling cascade. However, the signal transduction mechanisms downstream of P2K1 activation remain incompletely understood. We conducted a comprehensive analysis of the P2K1 interactome using co-immunoprecipitation-coupled tandem mass spectrometry, leading to the identification of 121 candidate proteins interacting with P2K1. In silico analysis narrowed down the candidates to 47 proteins, including Ca2+-binding proteins, ion transport-related proteins, and receptor kinases. To investigate their involvement in eATP signaling, we employed a screening strategy based on changes in gene expression in response to eATP in mutants of the identified interactors. This screening revealed several Ca2+-dependent protein kinases (CPKs) that significantly affected the expression of eATP-responsive genes, suggesting their potential roles in eATP signaling. Notably, CPK28 and CPK6 showed physical interactions with P2K1 both in yeast and plant systems. Calcium influx and gene expression studies demonstrated that CPK28 perturbed eATP-induced Ca2+ mobilization and some early transcriptional responses. Overexpression of CPK28 resulted in an antagonistic physiological response to P2K1-mediated eATP signaling during both plant growth and defense responses to the necrotrophic pathogen Botrytis cinerea. Our findings highlight CPK28, among other CPKs, as a modulator of P2K1-mediated eATP signaling, providing valuable insights into the coordination of eATP signaling in plant growth and immunity.
Assuntos
Proteínas de Arabidopsis , Arabidopsis , Regulação da Expressão Gênica de Plantas , Proteínas Quinases , Transdução de Sinais , Trifosfato de Adenosina/metabolismo , Arabidopsis/genética , Arabidopsis/metabolismo , Arabidopsis/crescimento & desenvolvimento , Arabidopsis/microbiologia , Arabidopsis/fisiologia , Proteínas de Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Botrytis/fisiologia , Doenças das Plantas/microbiologia , Doenças das Plantas/imunologia , Doenças das Plantas/genética , Proteínas Quinases/metabolismo , Proteínas Quinases/genéticaRESUMO
Powdery scab disease, caused by the soilborne protist Spongospora subterranea f. sp. subterranea, poses a major constraint to potato production worldwide. Disease symptoms include damage to the tuber skin and the formation of root galls. This study aimed to investigate the potential mechanism behind the formation of sporosori, which are aggregates of resting spores, within root galls. Scanning electron microscopy analysis revealed that the early stage of gall formation, characterized by a white color, involved the accumulation of starch grains, which later disappeared as the gall matured and turned brown. The mature brown galls were found to contain fully formed sporosori. Light microscopy examination of ultramicrotome sections of the root galls showed that the high-amylopectin starches were surrounded by a plasmodium, a precursor to sporosorus. These findings suggest that starch grains contribute to the formation of a sponge-like structure within the sporosori. A significant reduction in total starch levels in both the root galls and their associated roots was observed compared with healthy roots. These findings indicate starch consumption by sporosori during the maturation of root galls. Interestingly, analysis of the transcript levels of starch-related genes showed downregulation of genes encoding starch degrading enzymes and an amylopectin-debranching enzyme, whereas genes encoding a starch synthase and a protein facilitating starch synthesis were upregulated in the infected roots. Overall, our results demonstrate that starch is consumed during sporosorus formation, and the pathogen likely manipulates starch homeostasis to its advantage for sporosorus development within the root galls.
Assuntos
Doenças das Plantas , Plasmodioforídeos , Amido , Amilopectina , Metabolismo dos Carboidratos , Plasmodioforídeos/genéticaRESUMO
Powdery scab is an important potato disease caused by the soilborne pathogen Spongospora subterranea f. sp. subterranea. Currently, reliable chemical control and resistant cultivars for powdery scab are unavailable. As an alternative control strategy, we propose a novel approach involving the effective delivery of a phytocytokine to plant roots by the rhizobacterium Bacillus subtilis. The modified strain is designed to secrete the plant elicitor peptide StPep1. In our experiments employing a hairy root system, we observed a significant reduction in powdery scab pathogen infection when directly applying the StPep1 peptide. Furthermore, our pot assay, which involved pretreating potato roots with StPep1-secreting B. subtilis, demonstrated a substantial decrease in disease symptoms, including reduced root galling and fewer tuber skin scabs. These findings underscore the potential of engineered bacteria as a promising strategy for safeguarding plants against powdery scab.
RESUMO
Potato mop-top virus (PMTV) is an emerging viral pathogen that causes tuber necrosis in potatoes. PMTV is composed of three single-stranded RNA segments: RNA1 encodes RNA-dependent RNA polymerase, RNA2 contains the coat protein (CP), and RNA3 harbors a triple gene block (TGB 1, TGB2, and TGB3). CP plays a role in viral transmission, while TGB is known to facilitate cell-to-cell and long-distance systemic movement. The role of CP in symptom development, specifically in the presence of TGB genes, was investigated using potato virus X (PVX) as a delivery vehicle to express PMTV genes in the model plant Nicotiana benthamiana. Plants expressing individual genes showed mild symptoms that included leaf curling and crumpling. Interestingly, symptom severity varied among plants infected with three different combinations: CP with TGB1, CP with TGB2, and CP with TGB3. Notably, the combination of CP and TGB3 induced a hypersensitive response, accompanied by stunted growth and downward curling and crumpling. These results suggest the potential role of TGB co-expressed with CP in symptom development during PMTV infection. Additionally, this study demonstrates the use of the PVX-based expression system as a valuable platform for assessing the role of unknown genes in viral pathogenicity.
Assuntos
Proteínas do Capsídeo , Nicotiana , Doenças das Plantas , Potexvirus , Solanum tuberosum , Proteínas do Capsídeo/genética , Proteínas do Capsídeo/metabolismo , Nicotiana/genética , Nicotiana/virologia , Nicotiana/metabolismo , Potexvirus/genética , Potexvirus/patogenicidade , Doenças das Plantas/virologia , Doenças das Plantas/genética , Solanum tuberosum/virologia , Solanum tuberosum/genética , Solanum tuberosum/metabolismo , Proteínas Virais/genética , Proteínas Virais/metabolismoRESUMO
Early detection of causal pathogens is important to prevent crop loss from diseases. However, some diseases, such as soilborne diseases, are difficult to diagnose due to the absence of visible or characteristic symptoms. In the present study, the use of the Oxford Nanopore MinION sequencer as a molecular diagnostic tool was assessed due to its long-read sequencing capabilities and portability. Nucleotide samples (DNA or RNA) from potato field soils were sequenced and analyzed using a locally curated pathogen database, followed by identification via sequence mapping. We performed computational speed tests of three commonly used mapping/annotation tools (BLAST, BWA-BLAST, and BWA-GraphMap) and found BWA-GraphMap to be the fastest tool for local searching against our curated pathogen database. The data collected demonstrate the high potential of Nanopore sequencing as a minimally biased diagnostic tool for comprehensive pathogen detection in soil from potato fields. Our GraphMap-based MinION sequencing method could be useful as a predictive approach for disease management by identifying pathogens present in field soil prior to planting. Although this method still needs further experimentation with a larger sample size for practical use, the data analysis pipeline presented can be applied to other cropping systems and diagnostics for detecting multiple pathogens.
Assuntos
Sequenciamento por Nanoporos , Solanum tuberosum , Solo , Sequenciamento por Nanoporos/métodosRESUMO
Calcium (Ca2+ ) signalling regulates salicylic acid (SA)-mediated immune response through calmodulin-meditated transcriptional activators, AtSRs/CAMTAs, but its mechanism is not fully understood. Here, we report an AtSR1/CAMTA3-mediated regulatory mechanism involving the expression of the SA receptor, NPR1. Results indicate that the transcriptional expression of NPR1 was regulated by AtSR1 binding to a CGCG box in the NPR1 promotor. The atsr1 mutant exhibited resistance to the virulent strain of Pseudomonas syringae pv. tomato (Pst), however, was susceptible to an avirulent Pst strain carrying avrRpt2, due to the failure of the induction of hypersensitive responses. These resistant/susceptible phenotypes in the atsr1 mutant were reversed in the npr1 mutant background, suggesting that AtSR1 regulates NPR1 as a downstream target during plant immune response. The virulent Pst strain triggered a transient elevation in intracellular Ca2+ concentration, whereas the avirulent Pst strain triggered a prolonged change. The distinct Ca2+ signatures were decoded into the regulation of NPR1 expression through AtSR1's IQ motif binding with Ca2+ -free-CaM2, while AtSR1's calmodulin-binding domain with Ca2+ -bound-CaM2. These observations reveal a role for AtSR1 as a Ca2+ -mediated transcription regulator in controlling the NPR1-mediated plant immune response.
Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/imunologia , Doenças das Plantas/imunologia , Fatores de Transcrição/metabolismo , Arabidopsis/metabolismo , Resistência à Doença , Ensaio de Desvio de Mobilidade Eletroforética , Regulação da Expressão Gênica de Plantas , Doenças das Plantas/microbiologia , Reguladores de Crescimento de Plantas/metabolismo , Pseudomonas syringae , Reação em Cadeia da Polimerase em Tempo Real , Salicilatos/metabolismoRESUMO
The role of small secreted peptides in plant defense responses to viruses has seldom been investigated. Here, we report a role for potato (Solanum tuberosum) PIP1, a gene predicted to encode a member of the pathogen-associated molecular pattern (PAMP)-induced peptide (PIP) family, in the response of potato to Potato virus Y (PVY) infection. We show that exogenous application of synthetic StPIP1 to potato leaves and nodes increased the production of reactive oxygen species and the expression of plant defense-related genes, revealing that StPIP1 triggers early defense responses. In support of this hypothesis, transgenic potato plants that constitutively overexpress StPIP1 had higher levels of leaf callose deposition and, based on measurements of viral RNA titers, were less susceptible to infection by a compatible PVY strain. Interestingly, systemic infection of StPIP1-overexpressing lines with PVY resulted in clear rugose mosaic symptoms that were absent or very mild in infected non-transgenic plants. A transcriptomics analysis revealed that marker genes associated with both pattern-triggered immunity and effector-triggered immunity were induced in infected StPIP1 overexpressors but not in non-transgenic plants. Together, our results reveal a role for StPIP1 in eliciting plant defense responses and in regulating plant antiviral immunity.
Assuntos
Potyvirus , Solanum tuberosum , Moléculas com Motivos Associados a Patógenos , Peptídeos , Doenças das Plantas , Solanum tuberosum/genéticaRESUMO
The first layer of plant immunity is deployed by recognition of pathogen-associated molecule patterns (PAMPs) and induction of early stress responses. Flagellin is the major protein component of the flagellum. Flagellin-derived peptide fragments such as Flg22, a short active peptide derived from the highly conserved part of the N-terminal region, are recognized as PAMPs by a specific perception system present in most higher plants. Some bacteria evade the plant recognition system by altering the Flg22 region in the flagellin. Instead, a small subset of plants (i.e., solanaceous plants) can sense these bacteria by recognizing a second region, termed FlgII-28. The function of FlgII-28 has been well-documented in tomato but not in potato plants. Here, we investigated the effect of FlgII-28 on several defense responses in potato. Cytosolic calcium (Ca2+) elevation is an early defense response upon pathogenic infection. We generated transgenic potato plants expressing aequorin, a nontoxic Ca2+-activated photoprotein. The results showed that FlgII-28 induced strong cytosolic Ca2+ elevation in a dose-dependent manner, whereas the response was attenuated when a Ca2+ channel blocker was added. In addition, the FlgII-28-triggered cytosolic Ca2+ elevation was shown to subsequently promote extracellular alkalinization, reactive oxygen species production, mitogen-activated protein kinase phosphorylation, and transcriptional reprogramming of defense-related genes in potato. Interestingly, all tested defense responses caused by FlgII-28 were significantly stronger than those caused by Flg22, suggesting that FlgII-28 acts as a primary flagellar PAMP to elicit multiple defense responses in potato.
Assuntos
Flagelina , Imunidade Vegetal , Solanum tuberosum , Cálcio/metabolismo , Citosol/química , Citosol/imunologia , Flagelina/genética , Flagelina/imunologia , Regulação da Expressão Gênica de Plantas , Imunidade Vegetal/genética , Solanum tuberosum/genética , Solanum tuberosum/imunologiaRESUMO
ATP is not only an essential metabolite of cellular biochemistry but also acts as a signal in the extracellular milieu. In plants, extracellular ATP is monitored by the purinergic receptor P2K1. Recent studies have revealed that extracellular ATP acts as a damage-associated molecular pattern in plants, and its signaling through P2K1 is important for mounting an effective defense response against various pathogenic microorganisms. Biotrophic and necrotrophic pathogens attack plants using different strategies, to which plants respond accordingly with salicylate-based or jasmonate/ethylene-based defensive signaling, respectively. Interestingly, defense mediated by P2K1 is effective against pathogens of both lifestyles, raising the question of the level of interplay between extracellular ATP signaling and that of jasmonate, ethylene, and salicylate. To address this issue, we analyzed ATP-induced transcriptomes in wild-type Arabidopsis (Arabidopsis thaliana) seedlings and mutant seedlings defective in essential components in the signaling pathways of jasmonate, ethylene, and salicylate (classic defense hormones) as well as a mutant and an overexpression line of the P2K1 receptor. We found that P2K1 function is crucial for faithful ATP-induced transcriptional changes and that a subset of genes is more responsive in the P2K1 overexpression line. We also found that more than half of the ATP-responsive genes required signaling by one or more of the pathways for the classical defense hormones, with the jasmonate-based signaling being more critical than others. By contrast, the other ATP-responsive genes were unaffected by deficiencies in signaling for any of the classical defense hormones. These ATP-responsive genes were highly enriched for defense-related Gene Ontology terms. We further tested the ATP-induced genes in knockout mutants of transcription factors, demonstrating that MYCs acting downstream of the jasmonate receptor complex and calmodulin-binding transcription activators are nuclear transducers of P2K1-mediated extracellular ATP signaling.
Assuntos
Trifosfato de Adenosina/metabolismo , Arabidopsis/metabolismo , Transcriptoma , Arabidopsis/genética , Ciclopentanos/metabolismo , Etilenos/metabolismo , Regulação da Expressão Gênica de Plantas , Oxilipinas/metabolismo , Reguladores de Crescimento de Plantas/metabolismo , Salicilatos/metabolismo , Plântula/genética , Plântula/metabolismo , Transdução de Sinais/genéticaRESUMO
Plants encrypt the perception of different pathogenic stimuli into specific intracellular calcium (Ca2+) signatures and subsequently decrypt the signatures into appropriate downstream responses through various Ca2+ sensors. Two microbe-associated molecular patterns (MAMPs), bacterial flg22 and fungal chitin, and one damage-associated molecular pattern (DAMP), AtPep1, were used to study the differential Ca2+ signatures in Arabidopsis leaves. The results revealed that flg22, chitin, and AtPep1 induced distinct changes in Ca2+ dynamics in both the cytosol and nucleus. In addition, Flg22 and chitin upregulated the expression of salicylic acid-related genes, ICS1 and EDS1, whereas AtPep1 upregulated the expression of jasmonic acid-related genes, JAZ1 and PDF1.2, in addition to ICS1 and EDS1. These data demonstrated that distinct Ca2+ signatures caused by different molecular patterns in leaf cells lead to specific downstream events. Furthermore, these changes in the expression of defense-related genes were disrupted in a knockout mutant of the AtSR1/CAMTA3 gene, encoding a calmodulin-binding transcription factor, in which a calmodulin-binding domain on AtSR1 was required for deciphering the Ca2+ signatures into downstream transcription events. These observations extend our knowledge regarding unique and intrinsic roles for Ca2+ signaling in launching and fine-tuning plant immune response, which are mediated by the AtSR1/CAMTA3 transcription factor.
Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Sinalização do Cálcio , Regulação da Expressão Gênica de Plantas , Moléculas com Motivos Associados a Patógenos/metabolismo , Fatores de Transcrição/metabolismo , Arabidopsis/genética , Arabidopsis/crescimento & desenvolvimento , Proteínas de Arabidopsis/genética , Doenças das Plantas/imunologia , Fatores de Transcrição/genéticaRESUMO
Damaged cells send various signals to stimulate defense responses. Recent identification and genetic studies of the plant purinoceptor, P2K1 (also known as DORN1), have demonstrated that extracellular ATP is a signal involved in plant stress responses, including wounding, perhaps to evoke plant defense. However, it remains largely unknown how extracellular ATP induces plant defense responses. Here, we demonstrate that extracellular ATP induces plant defense mediated through activation of the intracellular signaling of jasmonate (JA), a well-characterized defense hormone. In Arabidopsis (Arabidopsis thaliana) leaves, ATP pretreatment induced resistance against the necrotrophic fungus, Botrytis cinerea The induced resistance was enhanced in the P2K1 receptor overexpression line, but reduced in the receptor mutant, dorn1-3 Mining the transcriptome data revealed that ATP induces a set of JA-induced genes. In addition, the P2K1-associated coexpression network contains defense-related genes, including those encoding jasmonate ZIM-domain (JAZ) proteins, which play key roles as repressors of JA signaling. We examined whether extracellular ATP impacts the stability of JAZ1 in Arabidopsis. The results showed that the JAZ1 stability decreased in response to ATP addition in a proteasome-dependent manner. This reduction required intracellular signaling via second messengers-cytosolic calcium, reactive oxygen species, and nitric oxide. Interestingly, the ATP-induced JAZ1 degradation was attenuated in the JA receptor mutant, coi1, but not in the JA biosynthesis mutant, aos, or upon addition of JA biosynthesis inhibitors. Immunoprecipitation analysis demonstrated that ATP increases the interaction between COI1 and JAZ1, suggesting direct cross talk between extracellular ATP and JA in intracellular signaling events. Taken together, these results suggest that extracellular ATP signaling directly impacts the JA signaling pathway to maximize plant defense responses.
Assuntos
Trifosfato de Adenosina/farmacologia , Arabidopsis/imunologia , Ciclopentanos/metabolismo , Espaço Extracelular/metabolismo , Oxilipinas/metabolismo , Transdução de Sinais/efeitos dos fármacos , Arabidopsis/efeitos dos fármacos , Arabidopsis/genética , Arabidopsis/microbiologia , Proteínas de Arabidopsis/metabolismo , Botrytis/fisiologia , Cálcio/metabolismo , Resistência à Doença/efeitos dos fármacos , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Genes de Plantas , Óxido Nítrico/metabolismo , Complexo de Endopeptidases do Proteassoma/metabolismo , Estabilidade Proteica/efeitos dos fármacos , Proteólise/efeitos dos fármacos , Espécies Reativas de Oxigênio/metabolismo , Proteínas Repressoras/metabolismo , Regulação para Cima/efeitos dos fármacos , Regulação para Cima/genéticaRESUMO
Abdominal ultrasonography revealed a low echoic mass in the upper abdomen of a 65-year-old man. He was referred to our department, where abdominal CT revealed a tumor with a 30-mm contrast effect on the distal side of the inferior part of the duodenum. Endoscopy revealed a submucosal tumor in the same region, and ultrasonic endoscopy showed a low echoic mass with a clear boundary derived from the muscle layer. The duodenum was partially resected based on a diagnosis of suspected gastrointestinal stromal tumors (GIST), and the skin tumor was simultaneously resected. An elastic, soft, 30-mm tumor mass was found in the upper duodenum during surgery, and small nodules of 3-5mm were identified throughout the 110-cm length of the jejunum at intervals of 20-30cm. The histopathological diagnosis was GIST and immunostaining showed the mass to be c-kit and CD34 positive. We diagnosed the skin tumor as a neurofibroma (von Recklinghausen disease). Mutational analysis of c-kit in the resected specimen showed no mutation, therefore suggesting that imatinib would not be effective. Since the nodules remaining in the small intestine might also be GIST, we established a policy of regular imaging assessments.
Assuntos
Tumores do Estroma Gastrointestinal/diagnóstico , Intestino Delgado/patologia , Neurofibromatose 1/diagnóstico , Idoso , Tumores do Estroma Gastrointestinal/tratamento farmacológico , Tumores do Estroma Gastrointestinal/cirurgia , Humanos , Mesilato de Imatinib , Masculino , Neurofibromatose 1/tratamento farmacológico , Neurofibromatose 1/cirurgia , Proteínas Proto-Oncogênicas c-kitRESUMO
Fungi that cause cereal rust diseases (genus Puccinia) are important pathogens of wheat globally. Upon infection, the fungus secretes a number of effector proteins. Although a large repository of putative effectors has been predicted using bioinformatic pipelines, the lack of available high-throughput effector screening systems has limited functional studies on these proteins. In this study, we mined the available transcriptomes of Puccinia graminis and P. striiformis to look for potential effectors that suppress host hypersensitive response (HR). Twenty small (<300 amino acids), secreted proteins, with no predicted functions were selected for the HR suppression assay using Nicotiana benthamiana, in which each of the proteins were transiently expressed and evaluated for their ability to suppress HR caused by four cytotoxic effector-R gene combinations (Cp/Rx, ATR13/RPP13, Rpt2/RPS-2, and GPA/RBP-1) and one mutated R gene-Pto(Y207D). Nine out of twenty proteins, designated Shr1 to Shr9 (suppressors of hypersensitive response), were found to suppress HR in N. benthamiana. These effectors varied in the effector-R gene defenses they suppressed, indicating these pathogens can interfere with a variety of host defense pathways. In addition to HR suppression, effector Shr7 also suppressed PAMP-triggered immune response triggered by flg22. Finally, delivery of Shr7 through Pseudomonas fluorescens EtHAn suppressed nonspecific HR induced by Pseudomonas syringae DC3000 in wheat, confirming its activity in a homologous system. Overall, this study provides the first evidence for the presence of effectors in Puccinia species suppressing multiple plant defense responses.
Assuntos
Proteínas de Bactérias/metabolismo , Basidiomycota/genética , Interações Hospedeiro-Patógeno , Doenças das Plantas/imunologia , Imunidade Vegetal , Triticum/imunologia , Proteínas de Bactérias/genética , Basidiomycota/fisiologia , Morte Celular , Expressão Gênica , Regulação da Expressão Gênica de Plantas , Genes Supressores , Hipersensibilidade , Doenças das Plantas/microbiologia , Folhas de Planta/genética , Folhas de Planta/imunologia , Folhas de Planta/microbiologia , Plantas Geneticamente Modificadas , Pseudomonas fluorescens/genética , Pseudomonas fluorescens/fisiologia , Espécies Reativas de Oxigênio/metabolismo , Nicotiana/genética , Nicotiana/imunologia , Nicotiana/microbiologia , Transcriptoma , Triticum/genética , Triticum/microbiologiaRESUMO
BACKGROUND: Although antithrombotic agents are widely used for cardiac and cerebrovascular disease prevention, they increase the risk of gastrointestinal (GI) bleeding. OBJECTIVE: To examine GI bleeding risk in association with an esophagogastroduodenoscopy (EGD) biopsy performed in patients without cessation of antithrombotic therapy. METHODS: This study was prospectively conducted at 14 centers. EGD biopsies were performed in patients receiving antithrombotic agents without cessation, as well as age- and sex-matched controls not receiving antithrombotic therapy. Patients treated with warfarin before the biopsy had a prothrombin time-international normalized ratio level <3.0. The proportion of GI bleeding events was compared between the groups. RESULTS: The patient group (n = 277) underwent a total of 560 biopsies while continuing antithrombotic therapy, of whom 24 were receiving multiple antiplatelet drugs, and 9 were receiving both antiplatelet and anticoagulant agents. The control patients (n = 263) underwent 557 biopsies. The upper-GI bleeding rate within 30 days after the EGD biopsy did not increase in patients without cessation of antithrombotic treatment, regardless of receiving single or multiple antithrombotic agents. CONCLUSIONS: We found no significant increase in upper-GI bleeding risk following an EGD biopsy in patients taking antithrombotic agents, suggesting its safety without the need for antithrombotic treatment interruption.
RESUMO
Although lipo-chitooligosaccharides (LCOs) are important signal molecules for plant-symbiont interactions, a number of reports suggest that LCOs can directly impact plant growth and development, separate from any role in plant symbioses. In order to investigate this more closely, maize and Setaria seedlings were treated with LCO and their growth was evaluated. The data indicate that LCO treatment significantly enhanced root growth. RNA-seq transcriptomic analysis of LCO-treated maize roots identified a number of genes whose expression was significantly affected by the treatment. Among these genes, some LCO-up-regulated genes are likely involved in root growth promotion. Interestingly, some stress-related genes were down-regulated after LCO treatment, which might indicate reallocation of resources from defense responses to plant growth. The promoter activity of several LCO-up-regulated genes using a ß-glucuronidase reporter system was further analysed. The results showed that the promoters were activated by LCO treatment. The data indicate that LCO can directly impact maize root growth and gene expression.
Assuntos
Quitina/análogos & derivados , Poaceae/crescimento & desenvolvimento , Transdução de Sinais , Carbono/química , Quitina/farmacologia , Quitosana , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Lipopolissacarídeos/farmacologia , Oligossacarídeos , Poaceae/química , Poaceae/efeitos dos fármacos , Poaceae/metabolismo , Plântula/química , Plântula/efeitos dos fármacos , Plântula/crescimento & desenvolvimento , Plântula/metabolismo , Análise de Sequência de RNA , Transdução de Sinais/efeitos dos fármacos , Transcriptoma/efeitos dos fármacos , Zea mays/química , Zea mays/efeitos dos fármacos , Zea mays/crescimento & desenvolvimento , Zea mays/metabolismoRESUMO
ATP, the universal energy currency of all organisms, is released into the extracellular matrix and serves as a signal among cells, where it is referred to as an extracellular ATP. Although a signalling role for extracellular ATP has been well studied in mammals over the last 40 years, investigations of such a role in plants are at an early stage. Recently, the first plant receptor for extracellular ATP, DOes not Respond to Nucleotides (DORN1), was identified in Arabidopsis thaliana by mutant screening. DORN1 encodes a legume-type lectin receptor kinase that is structurally distinct from the mammalian extracellular ATP receptors. In the present review, we highlight the genetic and biochemical evidence for the role of DORN1 in extracellular ATP signalling, placing this within the wider context of extracellular ATP signalling during plant stress responses.
Assuntos
Trifosfato de Adenosina/metabolismo , Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Espaço Extracelular/metabolismo , Proteínas Quinases/metabolismo , Arabidopsis/imunologia , Imunidade Vegetal , Lectinas de Plantas/metabolismo , Proteínas Serina-Treonina Quinases/metabolismo , Estrutura Terciária de Proteína , Estresse FisiológicoRESUMO
Legumes (members of family Fabaceae) establish a symbiotic relationship with nitrogen-fixing soil bacteria (rhizobia) to overcome nitrogen source limitation. Single root hair epidermal cells serve as the entry point for bacteria to infect the host root, leading to development of a new organ, the nodule, which the bacteria colonize. In the present study, the putative role of a soybean acyl carrier protein (ACP), GmACP (Glyma18g47950), was examined in nodulation. ACP represent an essential cofactor protein in fatty acid biosynthesis. Phylogenetic analysis of plant ACP protein sequences showed that GmACP was classified in a legume-specific clade. Quantitative reverse-transcription polymerase chain reaction analysis demonstrated that GmACP was expressed in all soybean tissues but showed higher transcript accumulation in nodule tissue. RNA interference-mediated gene silencing of GmACP resulted in a significant reduction in nodule numbers on soybean transgenic roots. Fluorescent protein-labeled GmACP was localized to plastids in planta, the site of de novo fatty acid biosynthesis in plants. Analysis of the fatty acid content of root tissue silenced for GmACP expression, as determined by gas chromatography-mass spectrometry, showed an approximately 22% reduction, specifically in palmitic and stearic acid. Taken together, our data provide evidence that GmACP plays an important role in nodulation.
Assuntos
Proteína de Transporte de Acila/genética , Regulação da Expressão Gênica de Plantas , Glycine max/genética , Rhizobium/fisiologia , Proteína de Transporte de Acila/classificação , Proteína de Transporte de Acila/metabolismo , Sequência de Aminoácidos , Sequência de Bases , Genes Reporter , Dados de Sequência Molecular , Família Multigênica , Fixação de Nitrogênio , Ácido Palmítico/metabolismo , Filogenia , Proteínas de Plantas/classificação , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Nodulação , Raízes de Plantas/citologia , Raízes de Plantas/genética , Raízes de Plantas/microbiologia , Raízes de Plantas/fisiologia , Plantas Geneticamente Modificadas , Alinhamento de Sequência , Análise de Sequência de DNA , Glycine max/citologia , Glycine max/microbiologia , Glycine max/fisiologia , Ácidos Esteáricos/metabolismo , Simbiose , Nicotiana/genética , Nicotiana/metabolismoRESUMO
Chitin is the second most abundant polysaccharide in nature, found in crustacean shells, insect exoskeletons and fungal cell walls. The action of chitin and chitin derivatives on plants has become a very interesting story of late. Chitin is a b1-4-linked polymer of N-acetyl-Dglucosamine(GlcNAc). In this unmodified form, chitooligosaccharides (degree of polymerization(dp) = 68)) are strong inducers of plant innate immunity. By contrast, when these chitooligosaccharides are acylated (so-called lipochitooligosaccharides, LCOs) and further modified, they can act as Nod factors, the key signaling molecules that play an important role in the initiation of the legumerhizobium symbiosis. In a similar form, these molecules can also act as Myc factors, the key signaling molecules involved in the arbuscular mycorrhizal (AM)symbiosis. It has been proposed that Nod factor perception might have evolved from the more ancient AM symbiosis. Increasing evidence now suggests that LCO perception might have evolved from plant innate immunity signaling. In this review, we will discuss the evolutionary origin of symbiotic LCO recognition.
Assuntos
Evolução Molecular , Fabaceae/microbiologia , Lipopolissacarídeos/metabolismo , Micorrizas/fisiologia , Rhizobium/fisiologia , Simbiose , Acilação , Quitina/química , Quitina/metabolismo , Fabaceae/genética , Fabaceae/fisiologia , Interações Hospedeiro-Patógeno , Lipopolissacarídeos/química , Modelos Biológicos , Micorrizas/genética , Peptidoglicano/química , Peptidoglicano/metabolismo , Imunidade Vegetal , Rhizobium/genética , Transdução de SinaisRESUMO
Root hairs are single hair-forming cells on roots that function to increase root surface area, enhancing water and nutrient uptake. In leguminous plants, root hairs also play a critical role as the site of infection by symbiotic nitrogen fixing rhizobia, leading to the formation of a novel organ, the nodule. The initial steps in the rhizobia-root hair infection process are known to involve specific receptor kinases and subsequent kinase cascades. Here, we characterize the phosphoproteome of the root hairs and the corresponding stripped roots (i.e. roots from which root hairs were removed) during rhizobial colonization and infection to gain insight into the molecular mechanism of root hair cell biology. We chose soybean (Glycine max L.), one of the most important crop plants in the legume family, for this study because of its larger root size, which permits isolation of sufficient root hair material for phosphoproteomic analysis. Phosphopeptides derived from root hairs and stripped roots, mock inoculated or inoculated with the soybean-specific rhizobium Bradyrhizobium japonicum, were labeled with the isobaric tag eight-plex iTRAQ, enriched using Ni-NTA magnetic beads and subjected to nanoRPLC-MS/MS1 analysis using HCD and decision tree guided CID/ETD strategy. A total of 1625 unique phosphopeptides, spanning 1659 nonredundant phosphorylation sites, were detected from 1126 soybean phosphoproteins. Among them, 273 phosphopeptides corresponding to 240 phosphoproteins were found to be significantly regulated (>1.5-fold abundance change) in response to inoculation with B. japonicum. The data reveal unique features of the soybean root hair phosphoproteome, including root hair and stripped root-specific phosphorylation suggesting a complex network of kinase-substrate and phosphatase-substrate interactions in response to rhizobial inoculation.