Metabolitos secundarios de naturaleza fenólica: papel en la respuesta defensiva de plantas de tomate

El ácido salicílico (SA) juega un papel fundamental en la respuesta defensiva de las plantas. Este compuesto se acumula en las mismas como consecuencia de infecciones patogénicas de tipo incompatible, y su aplicación exógena induce resistencia. Asimismo, plantas transgénicas incapaces de acumularlo presentan una mayor susceptibilidad a patógenos de distinta naturaleza. Por otra parte, el ácido gentísico (GA, ácido 2,5-dihidroxibenzoico) se acumula en plantas en infecciones compatibles no necrotizantes. La aplicación exógena de GA induce un conjunto de proteínas de defensa PR (Pathogenesis related) distintas a las que induce el SA, por lo que podría tener un papel complementario en la señalización frente a patógenos en plantas. Ambos compuestos se acumulan en plantas en forma de glicósidos, es decir, conjugados a una o más moléculas de azúcar. Estas reacciones de conjugación son catalizadas por proteínas denominadas glicosiltransferasas. En plantas de tomate el SA se acumula como SA 2-O-ß-glucósido, unido a una molécula de glucosa, mientras el GA lo hace en forma de GA 5-O-ß-xilósido, unido a xilosa. GAGT (Gentisic Acid Glycosyl Transferase) ha sido descrita como la proteína que conjuga GA en tomate. Dado que la glicosilación de metabolitos es una forma rápida de inactivarlos, la existencia de esta proteína con actividad conjugadora de GA refuerza la idea del ácido gentísico (GA) como molécula señal complementaria al SA en la interacción planta-patógeno. Por otra parte, la proteína Twi1 (Tomato wound inducible), descrita en tomate como una posible glicosiltransferasa debido a sus características comunes con este grupo de proteínas, presenta inducción por SA y otros compuestos de naturaleza fenólica, además de herida e interacciones de tipo incompatible. Trabajos en los que se ha llevado a cabo la sobreexpresión o el silenciamiento de una GT han puesto de manifiesto cómo ello conlleva la aparición de resistencia o susceptibilidad frente a una infección patogénica. Por tanto, las GTs tienen un papel fundamental en la respuesta defensiva de la planta, modulando los niveles de moléculas que intervienen en dicha respuesta. Por otra parte, se han realizado estudios dirigidos a elucidar la implicación de compuestos del metabolismo secundario en la interacción de plantas de tomate con distintos patógenos. Ello ha permitido detectar cambios concretos de los niveles de un número determinado de metabolitos a lo largo de las infecciones, como son cuatro amidas derivadas del ácido hidroxicinámico (HCAAs) que se acumulan en plantas de tomate infectadas con la bacteria Pseudomonas syringae pv. tomato. Las HCAAs son un conjunto de metabolitos, pertenecientes al grupo de los fenilpropanoides, de bajo peso molecular y que se caracterizan por la presencia de nitrógeno en su estructura. En su ruta de biosíntesis participan diversos enzimas tales como la fenilalanina amonio liasa (PAL), la tirosina descarboxilasa (TYDC) o la tiramina hidroxicinamoil transferasa (THT). La acumulación en tomate de las cuatro amidas como consecuencia de la infección bacteriana va acompañada de la inducción del isoenzima THT1-3. La obtención de plantas transgénicas que sobreexpresen o silencien las proteínas GAGT, Twi1 y THT1-3 permitirá llevar a cabo ensayos de resistencia frente a infecciones patogénicas que contribuyan al conocimiento del sistema defensivo de las plantas, tanto en sus aspectos de señalización como en los referidos a componentes de la respuesta final de la planta. Al mismo tiempo, esta estrategia puede constituir, en sí misma, un medio de obtención de plantas más resistentes frente a ataques patogénicos de diversa naturaleza.Campos Beneyto, L. (2014). Metabolitos secundarios de naturaleza fenólica: papel en la respuesta defensiva de plantas de tomate [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/44236TESI

Estudio de la actividad in vivo de la gentisato-glicosiltransferasa GAGT y la posible glicosiltransferasa Twi1 de tomate mediante expresión transitoria en Nicotiana benthamiana

El ácido salicílico (SA) juega un papel fundamental en la respuesta defensiva de las plantas. Este compuesto se acumula en las mismas como consecuencia de interacciones patogénicas incompatibles y su aplicación exógena induce resistencia. Por otra parte, en nuestro laboratorio se identificó el ácido gentísico (GA, ácido 2,5-dihidroxibenzoico), un derivado del SA, como un compuesto fenólico que se acumula en infecciones compatibles no necrotizantes. Su aplicación exógena induce un conjunto de proteínas PR (Pathogenesis-Related) distintas a las que induce el SA, por lo que podría tener un papel complementario en la señalización frente a patógenos en plantas. Tanto SA como GA se acumulan en forma de glicósidos. Las reacciones de conjugación consisten en la unión de una o varias moléculas de azúcar al metabolito en cuestión y son catalizadas por glicosiltransferasas. En publicaciones previas, hemos descrito GAGT (Gentisic Acid Glycosyl Transferase) como la proteína que conjuga GA en tomate. Por otra parte, la proteína de tomate Twi1, que se induce en respuesta a herida, interacciones de tipo incompatible y compuestos fenólicos tales como el ácido salicílico (SA), fue identificada como posible glicosiltransferasa, aunque no ha sido caracterizada hasta el momento. En el presente trabajo se ha llevado a cabo la sobreexpresión de GAGT y Twi1 mediante experimentos de expresión transitoria. Para ello, los cDNAs de GAGT y Twi1 han sido clonados en los plásmidos binarios pGWB8 y pGWB9 (tecnología Gateway), respectivamente. Ambos poseen el promotor constitutivo 35S de CaMV y una cola de histidinas en su extremo C-t o N-t. Posteriormente, se ha realizado la agroinfiltración de dichas construcciones, así como de sus correspondientes controles, en hojas de N. benthamiana. La presencia de los transcritos se ha confirmado por RT-PCR. Para el estudio de la actividad in vivo, las plantas agroinoculadas han sido embebidas en soluciones de GA o SA, y posteriormente se han analizado los niveles libres y conjugados de dichos fenólicos mediante HPLC.Campos Beneyto, L. (2011). Estudio de la actividad in vivo de la gentisato-glicosiltransferasa GAGT y la posible glicosiltransferasa Twi1 de tomate mediante expresión transitoria en Nicotiana benthamiana. http://hdl.handle.net/10251/15604Archivo delegad

Tomato glycosyltransferase Twi1 plays a role in flavonoid glycosylation and defence against virus

[EN] Background: Secondary metabolites play an important role in the plant defensive response. They are produced as a defence mechanism against biotic stress by providing plants with antimicrobial and antioxidant weapons. In higher plants, the majority of secondary metabolites accumulate as glycoconjugates. Glycosylation is one of the commonest modifications of secondary metabolites, and is carried out by enzymes called glycosyltransferases. Results: Here we provide evidence that the previously described tomato wound and pathogen-induced glycosyltransferase Twi1 displays in vitro activity toward the coumarins scopoletin, umbelliferone and esculetin, and the flavonoids quercetin and kaempferol, by uncovering a new role of this gene in plant glycosylation. To test its activity in vivo, Twi1-silenced transgenic tomato plants were generated and infected with Tomato spotted wilt virus. The Twi1- silenced plants showed a differential accumulation of Twi1 substrates and enhanced susceptibility to the virus. Conclusions: Biochemical in vitro assays and transgenic plants generation proved to be useful strategies to assign a role of tomato Twi1 in the plant defence response. Twi1 glycosyltransferase showed to regulate quercetin and kaempferol levels in tomato plants, affecting plant resistance to viral infection.This work was supported by grant BIO2012-33419 from the Direccion General de Programas y Transferencia de Conocimiento, Spanish Ministry of Science and Innovation, and grant AICO/2017/048 from the Valencian Local Government (Generalitat Valenciana, Spain). LC was supported by a predoctoral fellowship (ACIF/2010/231) from the Valencian Local Government (Generalitat Valenciana, Spain). 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Transgenic tomato plants overexpressing tyramine N-hydroxycinnamoyltransferase exhibit elevated hydroxycinnamic acid amide levels and enhanced resistance to Pseudomonas syringae. Mol Plant-Microbe Interact. 2014;27(10):1159–69.Conejero V, Semancik J. Analysis of the proteins in crude plant extracts by polyacrylamide gel electrophoresis. Phytopathology. 1977;67:1424–6.Yalpani N, Leon J, Lawton

A Non-targeted Metabolomics Approach Unravels the VOCs Associated with the Tomato Immune Response against Pseudomonas syringae

[EN] Volatile organic compounds (VOCs) emitted by plants are secondary metabolites that mediate the plant interaction with pathogens and herbivores. These compounds may perform direct defensive functions, i. e., acting as antioxidant, antibacterial, or antifungal agents, or indirectly by signaling the activation of the plant's defensive responses. Using a non-targeted GC-MS metabolomics approach, we identified the profile of the VOCs associated with the differential immune response of the Rio Grande tomato leaves infected with either virulent or avirulent strains of Pseudomonas syringae DC3000 pv. tomato. The VOC profile of the tomato leaves infected with avirulent bacteria is characterized by esters of (Z)-3-hexenol with acetic, propionic, isobutyric or butyric acids, and several hydroxylated monoterpenes, e. g., linalool, a -terpineol, and 4-terpineol, which defines the profile of an immunized plant response. In contrast, the same tomato cultivar infected with the virulent bacteria strain produced a VOC profile characterized by monoterpenes and SA derivatives. Interestingly, the differential VOCs emission correlated statistically with the induction of the genes involved in their biosynthetic pathway. Our results extend plant defense system knowledge and suggest the possibility for generating plants engineered to over-produce these VOCs as a complementary strategy for resistance.This work was funded by Grant BIO2012-33419 from the Spanish Ministry of Economy and Competitiveness.López-Gresa, MP.; Lisón, P.; Campos Beneyto, L.; Rodrigo Bravo, I.; Rambla Nebot, JL.; Granell Richart, A.; Conejero Tomás, V.... (2017). A Non-targeted Metabolomics Approach Unravels the VOCs Associated with the Tomato Immune Response against Pseudomonas syringae. Frontiers in Plant Science. 8. doi:10.3389/fpls.2017.01188S

Salicylic acid and gentisic acid induce RNA silencing-related genes and plant resistance to RNA pathogens

[EN] We have observed that treatments with salicylic acid (SA) or gentisic acid (GA) induced resistance to RNA pathogens such as ToMV and CEVd in tomato and Gynura auriantiaca, respectively. Accumulation of SA and GA has been found to occur in plants infected by these pathogens, thus pointing out a possible defence role of both molecules. To study the molecular basis of the observed induced resistance to RNA pathogens the induction of silencing-related genes by SA and GA was considered. For that purpose, we searched for tomato genes which were orthologous to those described in Arabidopsis thaliana, such as AtDCL1, AtDCL2, AtDCL4, AtRDR1, AtRDR2 and AtRDR6, and we tracked their induction in tomato along virus and viroid infections. We observed that CEVd significantly induced all these genes in tomato, with the exception of ToRDR6, being the induction of ToDCL4 the most outstanding. Regarding the ToMV asymptomatic infection, with the exception of ToRDR2, we observed a significant induction of all the indicated silencing-related genes, being ToDCL2 the most induced gene. Subsequently, we analyzed their transcriptional activation by SA and at the time when ToMV was inoculated on plants. ToDCL2, ToRDR1 and ToRDR2 were significantly induced by both SA and GA, whereas ToDCL1 was only induced by SA. Such an induction resulted more effective by SA treatment, which is in agreement with the stronger SAinduced resistance observed. Our results suggest that the observed delay in the RNA pathogen accumulation could be due to the pre-induction of RNA silencing-related genes by SA or GA. 2014 Elsevier Masson SAS. All rights reservedThe authors are grateful to Cristina Torres and Asuncion Sauri for technical support. This work was supported by Grant BFU2009-11958 from Direccion General de Programas y Transferencia de Conocimiento, from Spanish Ministry of Science and Innovation, and Grants PAID-06-08-3295 and SP20120576 from Universitat Politecnica de Valencia (UPV). Laura Campos was the recipient of a predoctoral fellowship ACIF/2010/231 from Generalitat Valenciana (Spain). Ma Pilar Lopez Gresa held a postdoctoral fellowship JAE-Doc_08_00402 from the Consejo Superior de Investigaciones Cientificas (Spain).Campos Beneyto, L.; Granell Albert, P.; Tarraga Herrero, S.; López Gresa, MP.; Conejero Tomás, V.; Belles Albert, JM.; Rodrigo Bravo, I.... (2014). Salicylic acid and gentisic acid induce RNA silencing-related genes and plant resistance to RNA pathogens. Plant Physiology and Biochemistry. 77:35-43. https://doi.org/10.1016/j.plaphy.2014.01.016S35437

Post–COVID-19 Conditions Among Children 90 Days After SARS-CoV-2 Infection

IMPORTANCE Little is known about the risk factors for, and the risk of, developing post-COVID-19 conditions (PCCs) among children. OBJECTIVES To estimate the proportion of SARS-CoV-2-positive children with PCCs 90 days after a positive test result, to compare this proportion with SARS-CoV-2-negative children, and to assess factors associated with PCCs. DESIGN, SETTING, AND PARTICIPANTS This prospective cohort study, conducted in 36 emergency departments (EDs) in 8 countries between March 7, 2020, and January 20, 2021, included 1884 SARS-CoV-2-positive children who completed 90-day follow-up; 1686 of these children were frequency matched by hospitalization status, country, and recruitment date with 1701 SARS-CoV-2-negative controls. EXPOSURE SARS-CoV-2 detected via nucleic acid testing. MAIN OUTCOMES AND MEASURES Post-COVID-19 conditions, defined as any persistent, new, or recurrent health problems reported in the 90-day follow-up survey. RESULTS Of 8642 enrolled children, 2368 (27.4%) were SARS-CoV-2 positive, among whom 2365 (99.9%) had index ED visit disposition data available; among the 1884 children (79.7%) who completed follow-up, the median age was 3 years (IQR, 0-10 years) and 994 (52.8%) were boys. A total of 110 SARS-CoV-2-positive children (5.8%; 95% CI, 4.8%-7.0%) reported PCCs, including 44 of 447 children (9.8%; 95% CI, 7.4%-13.0%) hospitalized during the acute illness and 66 of 1437 children (4.6%; 95% CI, 3.6%-5.8%) not hospitalized during the acute illness (difference. 5.3%; 95% CI, 2.5%-8.5%). Among SARS-CoV-2-positive children, the most common symptom was fatigue or weakness (21 [1.1%]). Characteristics associated with reporting at least 1 PCC at 90 days included being hospitalized 48 hours or more compared with no hospitalization (adjusted odds ratio [aOR], 2.67 [95% CI, 1.63-4.38]); having 4 or more symptoms reported at the index ED visit compared with 1 to 3 symptoms (4-6 symptoms: aOR, 2.35 [95% CI, 1.28-4.31]; >= 7 symptoms: aOR, 4.59 [95% CI, 2.50 8.44]); and being 14 years of age or older compared with younger than 1 year (aOR, 2.67 [95% CI, 1.43-4.99]). SARS-CoV-2-positive children were more likely to report PCCs at 90 days compared with those who tested negative, both among those who were not hospitalized (55 of 1295 [4.2%; 95% CI, 3.2%-5.5%] vs 35 of 1321[2.7%; 95% CI, 1.9%-3.7%]; difference, 1.6% [95% CI, 0.2%-3.0%]) and those who were hospitalized (40 of 391[10.2%; 95% CI, 7.4%-13.7%] vs 19 of 380 [5.0%; 95% CI, 3.0%-7.7%]; difference, 5.2% [95% CI, 1.5%-9.1%]). In addition, SARS-CoV-2 positivity was associated with reporting PCCs 90 days after the index ED visit (aOR, 1.63 [95% CI, 1.14-2.35]), specifically systemic health problems (eg, fatigue, weakness, fever; aOR, 2.44 [95% CI, 1.19-5.00]). CONCLUSIONS AND RELEVANCE In this cohort study, SARS-CoV-2 infection was associated with reporting PCCs at 90 days in children. Guidance and follow-up are particularly necessary for hospitalized children who have numerous acute symptoms and are older.This studywas supported by grants from the Canadian Institutes of Health Research (operating grant: COVID-19-clinical management); the Alberta Health Services-University of Calgary-Clinical Research Fund; the Alberta Children's Hospital Research Institute; the COVID-19 Research Accelerator Funding Track (CRAFT) Program at the University of California, Davis; and the Cincinnati Children's Hospital Medical Center Division of Emergency Medicine Small Grants Program. Dr Funk is supported by the University of Calgary Eyes-High PostDoctoral Research Fund. Dr Freedman is supported by the Alberta Children's Hospital Foundation Professorship in Child Health andWellness

Transgenic tomato plants overexpressing tyramine N-hydroxycinnamoyltransferase exhibit elevated hydroxycinnamic acid amide levels and enhanced resistance to Pseudomonas syringae

This paper has not yet been peer reviewed, copyedited or proofread. The final published version may differ. The final version of the article is available at: http://dx.doi.org/10.1094/MPMI-04-14-0104-R © 2014 The American Phytopathological Society[EN] Hydroxycinnamic acid amides (HCAA) are secondary metabolites involved in plant development and defense that have been widely reported throughout the plant kingdom. These phenolics show antioxidant, antiviral, antibacterial, and antifungal activities. Hydroxycinnamoyl-CoA: tyramine N-hydroxycinnamoyl transferase (THT) is the key enzyme in HCAA synthesis and is induced in response to pathogen infection, wounding, or elicitor treatments, preceding HCAA accumulation. We have engineered transgenic tomato plants overexpressing tomato THT. These plants displayed an enhanced THT gene expression in leaves as compared with wild type (WT) plants. Consequently, leaves of THT-over-expressing plants showed a higher constitutive accumulation of the amide coumaroyltyramine (CT). Similar results were found in flowers and fruits. Moreover, feruloyltyramine (FT) also accumulated in these tissues, being present at higher levels in transgenic plants. Accumulation of CT, FT and octopamine, and noradrenaline HCAA in response to Pseudomonas syringae pv. tomato infection was higher in transgenic plants than in the WT plants. Transgenic plants showed an enhanced resistance to the bacterial infection. In addition, this HCAA accumulation was accompanied by an increase in salicylic acid levels and pathogenesis-related gene induction. Taken together, these results suggest that HCAA may play an important role in the defense of tomato plants against P. syringae infection.The authors are grateful to C. Torres, A. Sauri, and T. Caballero for technical support. We also thank C. Gomez-Mena for her assistance in tomato flower sampling. This work was supported by Grant BIO2012-33419 from the Direccion General de Programas y Transferencia de Conocimiento, from the Spanish Ministry of Science and Innovation. L. Campos was the recipient of a predoctoral fellowship ACIF/2010/231 from Generalitat Valenciana (Spain). The work presented here was carried out in collaboration between all authors. J. M. Belles defined the research theme. L. Campos, L. Zacares and M. P. Lopez-Gresa carried out the laboratory experiments. P. Lison and I. Rodrigo contributed to the experimental design and the interpretation of the data. L. Campos drafted the article. M. P. Lopez-Gresa, P. Lison and I. Rodrigo participated in revising it critically for important intellectual content. J. M. Belles and V. Conejero gave the final approval of the version to be published. Each author has participated sufficiently in the work to take public responsibility for the content.Campos Beneyto, L.; Lisón Párraga, MP.; López Gresa, MP.; Rodrigo Bravo, I.; Zacarés Sanmartín, L.; Conejero Tomás, V.; Belles Albert, JM. (2014). Transgenic tomato plants overexpressing tyramine N-hydroxycinnamoyltransferase exhibit elevated hydroxycinnamic acid amide levels and enhanced resistance to Pseudomonas syringae. Molecular Plant-Microbe Interactions. 27(10):1159-1169. doi:10.1094/MPMI-04-14-0104-RS11591169271

Plant responses underlying nonhost resistance of Citrus limon against Xanthomonas campestris pv. campestris

Citrus is an economically important fruit crop that is severely afflicted by citrus canker, a disease caused by Xanthomonas citri ssp. citri (X. citri); thus, new sustainable strategies to manage this disease are needed. Although all Citrus spp. are susceptible to this pathogen, they are resistant to other Xanthomonas species, exhibiting non-host resistance (NHR), for example, to the brassica pathogen X. campestris pv. campestris (Xcc) and a gene-for-gene host defence response (HDR) to the canker-causing X. fuscans ssp. aurantifolii (Xfa) strain C. Here, we examine the plant factors associated with the NHR of C. limon to Xcc. We show that Xcc induced asymptomatic type I NHR, allowing the bacterium to survive in a stationary phase in the non-host tissue. In C. limon, this NHR shared some similarities with HDR; both defence responses interfered with biofilm formation, and were associated with callose deposition, induction of the salicylic acid (SA) signalling pathway and the repression of abscisic acid (ABA) signalling. However, greater stomatal closure was seen during NHR than during HDR, together with different patterns of accumulation of reactive oxygen species and phenolic compounds and the expression of secondary metabolites. Overall, these differences, independent of Xcc type III effector proteins, could contribute to the higher protection elicited against canker development. We propose that Xcc may have the potential to steadily activate inducible defence responses. An understanding of these plant responses (and their triggers) may allow the development of a sustained and sustainable resistance to citrus canker.Fil: Chiesa, Maria Amalia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Investigaciones en Ciencias Agrarias de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Agrarias. Instituto de Investigaciones en Ciencias Agrarias de Rosario; Argentina. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Investigaciones en Ciencias Agrarias de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Agrarias. Instituto de Investigaciones en Ciencias Agrarias de Rosario; ArgentinaFil: Roeschlin, Roxana Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Investigaciones en Ciencias Agrarias de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Agrarias. Instituto de Investigaciones en Ciencias Agrarias de Rosario; Argentina. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas; Argentina. Universidad Católica de Santa Fe; ArgentinaFil: Favaro, María Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; Argentina. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas; Argentina. Universidad Nacional del Litoral; ArgentinaFil: Uviedo, Facundo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; ArgentinaFil: Campos Beneyto, Laura. Universidad Politécnica de Valencia; EspañaFil: D'andrea, Rodrigo Matias. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; Argentina. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas; ArgentinaFil: Gadea, José. Universidad Politécnica de Valencia; EspañaFil: Marano, María Rosa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; Argentina. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas; Argentin

Identification of defence metabolites in tomato plants infected by the bacterial pathogen Pseudomonas syringae

[EN] In the present work, we aimed to define the chemical nature of the phenylpropanoids induced during the interaction of the tomato plant. cultivar Rutgers, with the bacterial pathogen Pseudomonas syringae pv. tomato. Using LC-MS and NMR spectroscopy, we determined the chemical structures of this class of metabolites, which accumulated in response to exposure to the pathogen. A rapid accumulation of phytoalexin hydroxycinnamic acid amides (HCAA) of noradrenaline (cis/trans N-p-coumaroylnoradrenaline and cis/trans N-feruloylnoradrenline) and octopamine (cis/trans N-p-coumaroyloctopamine and cis/trans N-feruloyloctopamine), chlorogenic acid (CGA), and the flavonoid rutin was detected after bacterial infiltration. Among them, cis N-p-coumaroylnoradrenaline, cis N-p-coumaroyloctopamine, and isomers cis/trans of N-feruloylnoradrenaline have never been described in the literature. Moreover, cis/trans isomers of N-feruloyloctopamine are identified for the first time as being associated with the tomato/P. syringae interaction. Inhibition of the P. syringae-induced ethylene by 2-aminoethoxyvinylglycine, markedly impaired the accumulation of HCAA in inoculated tomato leaves, but it had no effect on CGA or rutin synthesis. On the other hand, the lack of accumulation of SA in NahG transgenic tomato plants, overexpressing a bacterial salicylic hydroxylase, did not prevent the enhancing of HCAA produced by P. syringae infection. Taken together, our results indicate that ethylene, but not SA, is essential for the synthesis of HCAA in response to bacterial infection of tomato leaves. Antibiotic activities of the induced metabolites were also studied. CGA induced a notable expression of the defence-related genes PR1 and P23. Moreover, trans-HCAA of noradrenaline and octopamine showed a potent free radical scavenging competence. In particular, trans N-feruloylnoradrenaline presented a very outstanding antioxidant activity, thus indicating that these compounds may play a role in the defence response of tomato plants against bacterial infection. (C) 2011 Elsevier B.V. All rights reserved.The authors want to thank Dr. Lynne Yenush for critical reading of the manuscript and exciting intellectual discussions. Dominique Melck, Estrella Mateos (ICB and ITQ NMR Service) for recording NMR spectra and Letizia Ciavatta for interpretation of the 600-MHz NMR spectra. This work was supported by Grant BFU2006-11546 from Direccion General de Programas y Transferencia de Conocimiento, from Spanish Ministry of Science and Innovation. M.P.L.G. was the recipient of a postdoctoral fellowship APOSTD/2007/128 from Generalitat Valencia (Spain).López Gresa, MP.; Torres Vidal, C.; Campos Beneyto, L.; Lisón Párraga, MP.; Rodrigo Bravo, I.; Belles Albert, JM.; Conejero Tomás, V. (2011). Identification of defence metabolites in tomato plants infected by the bacterial pathogen Pseudomonas syringae. Environmental and Experimental Botany. 74:216-228. https://doi.org/10.1016/j.envexpbot.2011.06.003S2162287

Effect of oral antiseptics in reducing SARS-CoV-2 infectivity: evidence from a randomized double-blind clinical trial

Background: In vitro studies have shown that several oral antiseptics have virucidal activity against SARS-CoV-2. Thus, mouthwashes have been proposed as an easy to implement strategy to reduce viral transmission. However, there are no data measuring SARS-CoV-2 viability after mouthwashes in vivo. Methods: In this randomized double-blind, five-parallel-group, placebo-controlled clinical trial, SARS-CoV-2 salivary viral load (by quantitative PCR) and its infectious capacity (incubating saliva in cell cultures) have been evaluated before and after four different antiseptic mouthwashes and placebo in 54 COVID-19 patients. Results: Contrary to in vitro evidence, salivary viral load was not affected by any of the four tested mouthwashes. Viral culture indicated that cetylpyridinium chloride (CPC) significantly reduced viral infectivity, but only at 1-hour post-mouthwash. Conclusion: These results indicate that some of the mouthwashes currently used to reduce viral infectivity are not efficient in vivo and, furthermore, that this effect is not immediate, generating a false sense of security.Trial registration: ClinicalTrials.gov identifier: NCT04707742.