Induction of cinnamate 4-hydroxylase and phenylpropanoids in virus-infected cucumber and melon plants

[EN] In the present work, we have looked for the nature of the phenylpropanoids biosynthesized during the plant-pathogen reaction of two systems, Cucumis sativus and Cucumis melo infected with either prunus necrotic ringspot virus (PNRSV) or melon necrotic spot virus (MNSV), respectively. An accumulation of p-coumaric, caffeic and/or ferulic acids was observed in infected plant extracts hydrolysed with P-glucosidase or esterase. Analysis of undigested samples by HPLC/ESI revealed that these compounds are mainly forming esters with glucose: 1-O-coumaroyl-beta-glucose, 1-O-caffeoyl-beta-glucose, and 1-O-fer-uloyl-beta-glucose. Cinnamic acid 4-hydroxylase (C4H, EC 1.14.13.11), the second enzyme of the plant phenylpropanoid pathway, plays a pivotal role in the synthesis of these hydroxycinnamic acids. Thus, we have isolated and characterised a cDNA clone encoding this enzyme from PNRSV-infected cucumber, and a partial cDNA from MNSV-infected melon leaves. The deduced amino acid sequence revealed a notable degree of identity with homologous C4H enzymes from other plant species. In agreement with the induction of the phenylpropanoids presently described, it is reported that in cucumber and melon leaves, both viral infections studied induced C4H mRNA expression. A similar induction was observed for the first pherylpropanoid biosynthetic enzyme, phyenylalanine ammonia-lyase (PAL, EC 4.3.1.5), and for chitinase and peroxidase defence-related genes.We gratefully acknowledge Dr. Lynne Yenush for critical reading of the manuscript and helpful discussions, and L. Latorre, and L. Coracha´n for the technical support in the greenhouse. The authors want to acknowledge the detailed suggestions of the referees. This work was supported by Grant BMC2000-1136 from Comisio´n Interministerial de Ciencia y Tecnologı´a, Spanish Ministry of Science and TechnologyS52453317

Induction of gentisic acid 5-O-beta-xylopyranoside in tomato and cucumber plants infected by different pathogens

[EN] Tomato plants infected with the citrus exocortis viroid exhibited strongly elevated levels of a compound identified as 2,5-dihydroxy-benzoic acid (gentisic acid, GA) 5-O-beta-D-xylopyranoside. The compound accumulated early in leaves expressing mild symptoms from both citrus exocortis viroid-infected tomato, and prunus necrotic ringspot virus-infected cucumber plants, and progressively accumulated concomitant with symptom development. The work presented here demonstrates that GA, mainly associated with systemic infections in compatible plant-pathogen interactions (Belles, J.M., Garro, R., Fayos, J., Navarro, P., Primo, J., Conejero, V., 1999. Gentisic acid as a pathogen-inducible signal, additional to salicylic acid for activation of plant defenses in tomato. Mol. Plant-Microbe Interact. 12, 2272351, is conjugated to xylose. Notably, this result contrasts with those previously found in other plant-pathogen interactions in which phenolics analogues of GA as benzoic or salicylic acids, are conjugated to glucose. (c) 2005 Elsevier Ltd. All rights reserved.This work has been supported by Grant #BMC2000-1136 from Comisión Interministerial de Ciencia y Tecnología, Spanish Ministry of Science and Technology.Fayos Febrer, J.; Belles Albert, JM.; López-Gresa, MP.; Primo Millo, J.; Conejero Tomás, V. (2006). Induction of gentisic acid 5-O-beta-xylopyranoside in tomato and cucumber plants infected by different pathogens. Phytochemistry. 67(2):142-148. doi:10.1016/j.phytochem.2005.10.014S14214867

Salicylic Acid Is Involved in the Basal Resistance of Tomato Plants to Citrus Exocortis Viroid and Tomato Spotted Wilt Virus

[EN] Tomato plants expressing the NahG transgene, which prevents accumulation of endogenous salicylic acid (SA), were used to study the importance of the SA signalling pathway in basal defence against Citrus Exocortis Viroid (CEVd) or Tomato Spotted Wilt Virus (TSWV). The lack of SA accumulation in the CEVd- or TSWV-infected NahG tomato plants led to an early and dramatic disease phenotype, as compared to that observed in the corresponding parental Money Maker. Addition of acibenzolar-S-methyl, a benzothiadiazole (BTH), which activates the systemic acquired resistance pathway downstream of SA signalling, improves resistance of NahG tomato plants to CEVd and TSWV. CEVd and TSWV inoculation induced the accumulation of the hydroxycinnamic amides p-coumaroyltyramine, feruloyltyramine, caffeoylputrescine, and feruloylputrescine, and the defence related proteins PR1 and P23 in NahG plants earlier and with more intensity than in Money Maker plants, indicating that SA is not essential for the induction of these plant defence metabolites and proteins. In addition, NahG plants produced very high levels of ethylene upon CEVd or TSWV infection when compared with infected Money Maker plants, indicating that the absence of SA produced additional effects on other metabolic pathways. This is the first report to show that SA is an important component of basal resistance of tomato plants to both CEVd and TSWV, indicating that SA-dependent defence mechanisms play a key role in limiting the severity of symptoms in CEVd- and TSWV-infected NahG tomato plants.This work was supported by grant BIO2012-33419 from the Spanish Ministry of Economy and Competitiveness received by JMB. The funder had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.López-Gresa, MP.; Lisón, P.; Yenush, L.; Conejero Tomás, V.; Rodrigo Bravo, I.; Belles Albert, JM. (2016). Salicylic Acid Is Involved in the Basal Resistance of Tomato Plants to Citrus Exocortis Viroid and Tomato Spotted Wilt Virus. PLoS ONE. 11(11). https://doi.org/10.1371/journal.pone.0166938S111

Induction of p-coumaroyidopamine and feruloyidopamine, two novel metabolites, in tomato by the bacterial pathogen Pseudomonas syringae

[EN] Inoculation of tomato plants (Solanum lycopersicum cv. Rutgers) with Pseudomonas syringae pv. tomato led to the production of a hypersensitive-like response in this pathovar of tomato. Accumulation of hydroxycinnamic acid amides (HCAA) of tyramine (p-coumaroyltyramine and feruloyltyramine) and dopamine (p-coumaroyldopamine and feruloyldopamine) was detected after bacterial infection. Two of them, p-coumaroyldopamine and feruloyldopamine, are described for the first time. The accumulation of HCAA was preceded by an increment of hydroxycinnamoyl-CoA:tyramine N-hydroxycinnamoyl transferase (THT) gene expression. HCAA also accumulated in transgenic NahG tomato plants overexpressing a bacterial salicylic hydroxylase. However, treatment of plants with the ethylene biosynthesis inhibitor, aminoethoxyvinilglycine, led to a reduction in the accumulation of THT transcripts and HCAA. Together, the results suggest that pathogen-induced induction of ethylene is essential for HCAA synthesis, whereas salicylic acid is not required for this response. In addition, notable antibacterial and antioxidant activities were found for the new HCAA, thus indicating that they could play a role in the defense of tomato plants against bacterial infection.This work was supported by Grant BMC2000-1136 from Comisión Interministerial de Ciencia y Tecnología, Spanish Ministry of Science and Technology. L. Zacarés was supported by a fellowship CTBPRB/2003/112 from Generalitat Valenciana, Conselleria de Empresa, Universidad y Ciencia, Spain. We gratefully acknowledge J. D. G. Jones (John Innes Centre, Norwich, U.K.) for the gift of seed of the transgenic NahG tomato plants and L. Yenush for critical reading of the manuscript and helpful discussions. I. Rodrigo is acknowledged for his continuous support during the course of this project.Zacarés Sanmartín, L.; López-Gresa, MP.; Fayos Febrer, J.; Primo Millo, J.; Belles Albert, JM.; Conejero Tomás, V. (2007). Induction of p-coumaroyidopamine and feruloyidopamine, two novel metabolites, in tomato by the bacterial pathogen Pseudomonas syringae. Molecular Plant-Microbe Interactions. 20(11):1439-1448. doi:10.1094 / MPMI -20-11-1439S14391448201

Bacillus subtilis IAB/BS03 as a potential biological control agent

[EN] We describe the efficacy of Bacillus subtilis strain IAB/BS03 in reducing disease incidence of B. subtilis IAB/BS03 as a foliar treatment against Botrytis cinerea and Pseudomonas syringae on greenhouse-grown tomato (Solanum lycopersicon) plants. We also tested the effect of foliar treatments on lettuce (Lactuca sativa) against lettuce downy mildew caused by Bremia lactucae in multiple trials under different field conditions. All the assays indicated that B. subtilis IAB/BS03 reduced disease. To ascertain the mechanism of action, the induction of pathogenesis-related (PR) proteins, the accumulation of salicylic acid and the activation of peroxidase caused by foliar or root treatments with B. subtilis IAB/BS03 were studied in tomato. A salicylic acid-independent induction of the antifungal protein PR1 was observed after treatment with B. subtilis IAB/BS03, with the strongest induction due to root treatment compared with foliar application. A metabolic analysis of B. subtilis IAB/BS03 culture broth using Ultra Performance Liquid Chromatography coupled with ultraviolet and mass spectrometric detection determined surfactin and iturin A isomers. These compounds have been described as antifungal and antibiotic lipopeptides. The results indicated that B. subtilis IAB/BS03 could be effectively used as a biocontrol agent.This work was funded by IAB S. L. (Investigaciones y Aplicaciones Biotecnologicas, S. L.), and by grant BIO2012-33419 from the Spanish Ministry of Economy and Competitiveness. Mayte Castellano was the recipient of a research grant also funded by IAB S. L. The authors would like to thank Cristina Torres (IBMCP, UPV-CSIC) for her excellent technical assistance.Hinarejos, E.; Castellano Pérez, M.; Rodrigo Bravo, I.; Belles Albert, JM.; Conejero Tomás, V.; López-Gresa, MP.; Lisón, P. (2016). Bacillus subtilis IAB/BS03 as a potential biological control agent. 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Sesión Necrológica en Homenaje al Excmo. Sr. Don Eduardo Primo Yúfera

The Dr. Eduardo Primo Yúfera was born on April 1, 1918 in Mazarrón, Murcia. Took possession as Academician of Honor on December 12, 2002. Died on October 28, 2007. The Necrological Session was celebrated on April 17, 2008, coordinated by the Academic Ana M ª Pascual-Leone Pascual, Vice-president of the Royal National Academy of Pharmacy, with the intervention of the Prof- Jose Pío Beltrán Porter, D. Vicente Conejero Tomás, D. Juan Juliá Igual and the Academic Ana M ª Pascual-Leone Pascual. It was presided by the Academic Maria Teresa Miras Portugal, Chairwoman of the Royal National Academy of Pharmacy.El Excmo. Señor Don Eduardo Primo Yúfera nació el 1 de abril de 1918 en Mazarrón, Murcia. Tomó posesión como Académico de Honor el día 12 de diciembre de 2002. Falleció el día 28 de octubre de 2007. La Sesión Necrológica se celebró el día 17 de abril de 2008, coordinada por la Excma. Sra. Dña. Ana Mª Pascual-Leone Pascual, Vicepresidenta de la Real Academia Nacional de Farmacia, con la intervención de los señores D. José Pío Beltrán Porter, D. Vicente Conejero Tomás, D. Juan Juliá Igual y de la Excma. Sra. Dña. Ana Mª Pascual-Leone Pascual. Fue presidida por la Excma. Señora Doña María Teresa Miras Portugal, Presidenta de la Real Academia Nacional de Farmacia

A new role for green leaf volatile esters in tomato stomatal defense against Pseudomonas syringe pv. tomato

[EN] The volatile esters of (Z)-3-hexenol with acetic, propionic, isobutyric, or butyric acids are synthesized by alcohol acyltransferases (AAT) in plants. These compounds are differentially emitted when tomato plants are efficiently resisting an infection with Pseudomonas syringae pv. tomato. We have studied the defensive role of these green leaf volatile (GLV) esters in the tomato response to bacterial infection, by analyzing the induction of resistance mediated by these GLVs and the phenotype upon bacterial infection of tomato plants impaired in their biosynthesis. We observed that treatments of plants with (Z)-3-hexenyl propionate (HP) and, to a greater extent with (Z)-3-hexenyl butyrate (HB), resulted in stomatal closure, PR gene induction and enhanced resistance to the bacteria. HB-mediated stomatal closure was also effective in several plant species belonging to Nicotiana, Arabidopsis, Medicago, Zea and Citrus genus, and both stomatal closure and resistance were induced in HB-treated NahG tomato plants, which are deficient in salicylic acid (SA) accumulation. Transgenic antisense AAT1 tomato plants, which displayed a reduction of ester emissions upon bacterial infection in leaves, exhibited a lower ratio of stomatal closure and were hyper-susceptible to bacterial infection. Our results confirm the role of GLV esters in plant immunity, uncovering a SA-independent effect of HB in stomatal defense. Moreover, we identified HB as a natural stomatal closure compound with potential agricultural applications.This work was funded by Grant AICO/2017/048 from the Generalitat Valenciana and by Grant INNVAL10/18/005 from the Agencia Valenciana de la Innovacio (Spain). We would like to thank the Metabolomics Service of the IBMCP (Valencia, Spain), especially to Teresa Caballero for her excellent technical support in the VOCs quantification. We also thank Eduardo Moya for technical assistance.López-Gresa, MP.; Payá, C.; Ozáez-Martínez, M.; Rodrigo Bravo, I.; Conejero Tomás, V.; Klee, H.; Belles Albert, JM.... (2018). A new role for green leaf volatile esters in tomato stomatal defense against Pseudomonas syringe pv. tomato. Frontiers in Plant Science. 9:1-12. https://doi.org/10.3389/fpls.2018.01855S112

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