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Increasing evidences highlight the importance of DEAD‐box RNA helicases in plant development and stress responses. In a previous study, we characterized the tomato res mutant (restored cell structure by salinity), showing chlorosis and development alterations that reverted under salt‐stress conditions. Map‐based cloning demonstrates that RES gene encodes SlDEAD39, a chloroplast‐targeted DEAD‐box RNA helicase. Constitutive expression of SlDEAD39 complements the res mutation, while the silencing lines had a similar phenotype than res mutant, which is also reverted under salinity. Functional analysis of res mutant proved SlDEAD39 is involved in the in vivo processing of the chloroplast, 23S rRNA, at the hidden break‐B site, a feature also supported by in vitro binding experiments of the protein. In addition, our results show that other genes coding for chloroplast‐targeted DEAD‐box proteins are induced by salt‐stress, which might explain the rescue of the res mutant phenotype. Interestingly, salinity restored the phenotype of res adult plants by increasing their sugar content and fruit yield. Together, these results propose an unprecedented role of a DEAD‐box RNA helicase in regulating plant development and stress response through the proper ribosome and chloroplast functioning, which, in turn, represents a potential target to improve salt tolerance in tomato crops., The role in plant development and fruit yield of a chloroplast‐targeted tomato (Solanum lycopersicum) DEAD‐box RNA helicase, SlDEAD39, is described. We propose that other DEAD‐box RHs might be partially redundant to SlDEAD39, mediating their specific functions in salt stress response.

Figure S3. Mapman stress diagrams. Differentially-expressed genes (DEGs) between res and WT in control and salt-stressed roots and leaves (200 mM NaCl for 5 days) involved in stress responses. Positive fold change values (red) indicate up-regulation (minimum fold-chang of 2.0) in res mutant compared to WT in each condition, whereas negative fold change values (blue) indicate down-regulation (minimum fold-change of − 2.0). Each coloured square represents an individual DEG. (PPTX 1566 kb)

Tomato CALCINEURIN B-LIKE PROTEIN 10 (SlCBL10) ensures plant growth by regulating proper distribution of Na+ and Ca2+ in the shoot apical meristem and developing organs under salt stress.

Resumen del trabajo presentado a la 4th International Conference on Analytical proteomics, celebrada en Caparica (Portugal) del 7 al 9 de septiembre de 2015., [Purpose]: Chilling injury (CI) constitute a set of physiological disorders causing detrimental effects on quality of fruits when stored after harvest at low temperatures to retard postharvest ripening and to extend their shelf-life. We have applied proteomics analysis to identify potential protein markers of CI and cold stress, and to detect biological processes affected by CI or involved in the plant organ response to deal with the cold stress. [Experimental description]: Fruits (bell peppers and tomatoes) were subjected to postharvest storage and posterior reconditioning at room temperature (20ºC). Storage was performed at a low temperature causing CI (1 and 2ºC respectively) for one batch of fruits and at a higher non-chilling temperature (10 and 12ºC respectively) for another batch used as control. Physiological parameters were determined, such as electrolyte leakage, ethylene production by GC-FID, respiration rate by GC-TCD, lipid peroxidation by MDA production, and sugars, organic acids and ascorbic acid by HPLC-RID/UV. Transmission electron microscopy studies were performed in bell pepper fruit sections. After extraction proteins were separated by two-dimensional differential in-gel electrophoresis (2D-DIGE) and proteins spots were identified after trypsin digestion with matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS). The search for peptides was fulfilled in batch mode using GPS Explorer v3.5 software with a licensed version of MASCOT, using viridiplantae and SGN databases. [Results and Conclusions]: A comparative proteomics analysis between fruits stored at chilling and non-chilling temperatures with posterior reconditioning was carried out. In tomato fruits storage at low temperature was ended just before visible CI symptoms appeared, but in bell pepper fruits this storage was extended until development of these symptoms. The proteomic study has allowed for the identification of processes occurring in fruit biology that are critically affected by chilling injury such as the activation of stress defense mechanisms starred by stressresponsive proteins (LEAs, HSPs and PRs), and alterations in carbohydrate/energy metabolism, particularly in enzymes from glycolysis, TCA and Calvin cycle, but also involved in stress signaling such as GAPDH, OGDH, INV and aldose-1-epimerase, this last one a potential new protein marker in cold stress. In tomato a remarkable down-regulation of a chloroplastic ATP synthase occurred, which may lead to depletion of intracellular ATP. In bell pepper fruits where CI progress was more advanced the proteomics analysis revealed alterations in redox homeostasis, protein abundance in the ascorbate-glutathione cycle is altered and CAT down-regulated., This work was supported by Fundación Séneca (1897/JLI/13).

Trabajo presentado al congreso "III Jornadas Bienales de jóvenes investigadores en proteómica" celebrado en Santiago de Compostela del 9 al 10 de febrero de 2012., Tomate (Solanum lycopersicum) y pimiento (Capsicum annuum), son dos especies hortofrutícolas pertenecientes a la familia Solanaceae susceptibles a sufrir daños por frío cuando se almacenan a bajas temperaturas, lo que afecta seriamente a la calidad de los frutos, siendo causa de importantes pérdidas económicas en el sector agro-alimentario. Una de las principales respuestas celulares al estrés por bajas temperaturas consiste en el mantenimiento de la homeostasis osmótica por la acumulación de osmolitos compatibles, para lo que tiene lugar la reprogramación de metabolismos energéticos como la glicólisis, el ciclo de Calvin y el ciclo de Krebs. Se ha abordado este estudio desde una perspectiva proteómica, comparando el proteoma de tomate y de pimiento sometidos a daños por frío para investigar las diferentes respuestas del metabolismo energético a las bajas temperaturas en frutos de estas dos especies. El análisis proteómico se ha realizado mediante electroforesis 2D-DIGE seguida de la identificación de las proteínas diferencialmente expresadas por MALDI-TOF-MS. Previamente a comparar los perfiles proteómicos de ambas especies, dentro de cada una de ellas se ha realizado una comparativa del perfil de frutos conservados a temperatura que inducen daños por frío y de frutos conservados a temperatura que no inducen dichos daños, con el fin de identificar las proteínas diferencialmente expresadas debido a la fisiopatía. Se han observado alteraciones en la fermentación y en el ciclo de Calvin en pimiento y cambios en el metabolismo de carbohidratos compuestos sacarosa), metabolismo de monosacáridos (glucosa) y cadena de transporte de electrones en tomate. En ambos frutos se han detectado modificaciones en la expresión de enzimas de la glicolisis y del ciclo de Krebs por efecto de la conservación refrigerada, hecho que pone de manifiesto la importancia que estos dos metabolismos parecen tener en la respuesta a los daños por frío., Este trabajo de investigación ha sido financiado por el Ministerio de Ciencia e Innovación (MICINN) (proyecto PIE2009-40I080), y por la Agencia de Ciencia y Tecnología de la Región de Murcia (Fundación SENECA) (proyecto 04553/GERM/06). PSB y ISE están contratadas en el marco del programa JAE-DOC del CSIC.

Comunicaciones a congresos

Trabajo presentado a la conferencia "Molecular Basis of Plant Stress" celebrado en Bulgaria del 21 al 23 de septiembre de 2011.-- FP7 REGPOT Project "BioSupport"., Tomato (Solanum lycopersicum L.) is the second most cultivated horticultural crop in the world in terms of harvested area and production, after the potato (FAOSTAT 2011, data from 2009). A main problem regarding its postharvest life is its sensitivity to low temperature stress during refrigerated storage, which constitutes a main obstacle for its long-term commercialization. This sensitivity is reflected in the physiopathy of chilling injury (CI), which negatively affects the final fruit quality. The main symptoms of CI-affected fruits are skin depressions, tissue decomposition and impaired ripening, which results in deficient flavour and aroma. Physiological and biochemical events involved in CI progress have been extensively described, but the precise molecular mechanisms that ultimately regulate the plant response to cold stress remain unclear. In order to investigate this response at molecular level in tomato fruit a proteomics strategy has undertaken. The proteome analysis provides a direct insight on the changes undergone by proteins, which are the major functional determinants of the cell machinery, in a certain biological situation such as low temperature stress. The protein expression profile of chilled tomato fruits has been compared with fruits stored at nonchilling temperature (control). The protein analysis has been performed by two-dimensional differential-in-gel-electrophoresis (2D-DIGE), and mass spectrometry of protein spots was applied to identify proteins differentially expressed. Comparative analysis revealed significant changes in abundance of 31 identified proteins between the proteomes of chilled and control fruits. Major modifications in the expression profile are related to those proteins specifically involved in stress (chaperonins and heat-shock proteins); cell wall biochemistry (hydrolytic enzymes), and carbohydrate metabolism (enzymes involved in glycolisis, tricarboxylic acids cycle, photosynthesis and sucrose biosynthesis)., This work was supported by the Spanish Ministry of Science and Innovation (MICINN) through grant and PIE2009-40I080, and by the Council of Science and Technology from the Spanish Region of Murcia (Fundación SENECA) through grant no. 04553/GERM/06.

[SPA] El melocotón (Prunus persica L.) es un fruto de gran importancia económica en la agricultura del Levante español, pero su reducido periodo de vida poscosecha constituye una seria limitación para su comercialización. Este problema se debe a su rápida senescencia causada por una elevada producción etileno autocatalítico al iniciarse su maduración, rasgo propio de los frutos climatéricos como los de esta especie. Se ha tratado de superar este problema mediante la aplicación de compuestos antagonistas de la acción de esta hormona a los frutos inmediatamente tras su recolección. Uno de los compuestos más novedosos y prometedores de este tipo es el radical libre del oxido nítrico (NO). Se ha realizado un tratamiento de melocotón var. ‘Rojo Rito’ con 5 ppm de NO en una atmósfera anaeróbica confinada durante 4 horas a 20ºC. Posteriormente los frutos se almacenaron en una cámara a 20ºC tomándose muestras a los 3, 6, 10 y 14 días para su análisis. Frutos no tratados y almacenados en idénticas condiciones fueron utilizados como control de la experiencia. Mediante este tratamiento previo se ha podido observar una mejora manifiesta en la conservación de los frutos a temperatura ambiente. La producción de etileno y la tasa respiratoria de los frutos tratados con NO era menor que la de los controles, al igual que el porcentaje de salida de electrolitos, parámetro utilizado para estimar la pérdida de semipermeabilidad de las membranas celulares y por tanto su grado de desintegración, que es un claro síntoma de senescencia. Los frutos tratados también mantenían una firmeza significativamente superior a lo largo de la conservación. Con respecto a otros parámetros de calidad como el parámetro de color ‘H’, la acidez valorable y el contenido en sólidos solubles no presentaron diferencias significativas entre frutos tratados y no tratados. [ENG] Peach (Prunus persica L.) is a fruit of great economical importance in the agricultural sector of South and East areas of Spain. One of the most serious limitations for the commercial potential of this produce is its reduced period of postharvest shelf life. This is due to the rapid onset of senescence, caused by the autocatalytic ethylene production occurring during ripening, a typical characteristic of climacteric fruits such as it is this species. One strategy used to try to overcome this drawback is the application of antagonistic compounds of ethylene action on harvested fruits. One of the most novel and promising compounds of this type is the nitric oxide (NO) free radical. A treatment of 5 ppm NO during 4 hours at 20ºC in a confined anaerobic atmosphere on peach fruit cv. ‘Rojo Rito’ has been carried out. The treated fruits were stored at 20ºC during 3, 6, 10 and 14 days. Non-treated fruits stored in identical conditions were used as controls of the assay. An apparent improvement on the quality and physiology of conservation at room temperature of the NOtreated fruit was observed. Ethylene production and respiratory rate of fruits treated with NO were lower than controls, as well as percentage of ion leakage, a parameter used to estimate cell membrane semipermeability loss and therefore disruption of membrane integrity, which is a typical symptom of senescence. Also treated fruits have got significant higher pulp firmness values along the conservation period. With regard to other quality parameters such as ‘H’ colour parameter, titrable acidity and soluble solids content, they do not show significant differences between both types of samples, NO-treated fruits and untreated ones. Queremos expresar nuestro agradecimiento a la cooperativa agrícola “Finca La Caprichosa” sita en Cieza (Murcia), y al Sr. J. Molina por la provisión de frutos para la realización de esta experiencia. Este trabajo ha sido financiado por el proyecto CICYT (Ref. AGL2003-01457).