RESUMEN

MAIN CONCLUSION: A survey of developed fruit gene-specific datasets and the implementation of a novel cis-element analysis tool indicate specific transcription factors as novel regulatory actors under HT response and CI protection. Heat treatment (HT) prior to cold storage (CS) has been successfully applied to ameliorate fruit chilling injury (CI) disorders. Molecular studies have identified several HT-driven benefits and putative CI-protective molecules and mechanisms. However, bioinformatic tools and analyses able to integrate fruit-specific information are necessary to begin functional studies and breeding projects. In this work, a HT-responsive gene dataset (HTds) and four fruit expression datasets (FEds), containing gene-specific information from several species and postharvest conditions, were developed and characterized. FEds provided information about HT-responsive genes, not only validating their sensitivity to HT in different systems but also revealing most of them as CS-responsive. A special focus was given to peach heat treatment-sensitive transcriptional regulation by the development of a novel Perl motif analysis software (cisAnalyzer) and a curated plant cis-elements dataset (PASPds). cisAnalyzer is able to assess sequence motifs presence, localization, enrichment and discovery on biological sequences. Its implementation for the enrichment analysis of PASPds motifs on the promoters of HTds genes rendered particular cis-elements that indicate certain transcription factor (TF) families as responsible of fruit HT-sensitive transcription regulation. Phylogenetic and postharvest expression data of these TFs showed a functional diversity of TF families, with members able to fulfil roles under HT, CS and/or both treatments. All integrated datasets and cisAnalyzer tool were deposited in FruitGeneDB (https://www.cefobi-conicet.gov.ar/FruitGeneDB/search1.php), a new available database with a great potential for fruit gene functional studies, including the markers of HT and CS responses whose study will contribute to unravel HT-driven CI-protection and select tolerant cultivars.

Asunto(s)

Frío , Bases de Datos Genéticas , Frutas/crecimiento & desarrollo , Frutas/genética , Calor , Motivos de Nucleótidos/genética , Preservación Biológica , Prunus persica/genética , Secuencia de Bases , Sitios de Unión , Regulación de la Expresión Génica de las Plantas , Genes de Plantas , Modelos Biológicos , Filogenia , Reguladores del Crecimiento de las Plantas/metabolismo , Regiones Promotoras Genéticas/genética , Prunus persica/crecimiento & desarrollo , Transducción de Señal , Programas Informáticos , Estrés Fisiológico/genética , Factores de Transcripción/metabolismo , Transcripción Genética

RESUMEN

Peach (Prunus persica) is an important economically temperate fruit. The development follows double sigmoid curve with four phases (S1-S4). We centered our work in the early development. In addition to S1, we studied the very early stage (E) characterized by the lag zone of the exponential growing phase S1, and the second stage (S2) when the pit starts hardening. "Dixiland" peach fruit were collected at 9 (E), 29 (S1), and 53 (S2) days after flowering (DAF) and endocarp and mesocarp were separated. There was a pronounced decrease in total protein content along development in both tissues. Quantitative proteomic allowed the identification of changes in protein profiles across development and revealed the main biochemical pathways sustaining tissue differentiation. Protein metabolism was the category most represented among differentially proteins in all tissues and stages. The decrease in protein synthesis machinery observed during development would be responsible of the protein fall, rather than a proteolytic process; and reduced protein synthesis during early development would reroute cell resources to lignin biosynthesis. These changes were accompanied by net decrease in total amino acids in E1-S1 and increase in S1-S2 transitions. Amino acid profiling, showed Asn parallels this trend. Concerted changes in Asn and in enzymes involved in its metabolism reveal that increased synthesis and decreased catabolism of Asn may conduct to an Asn increase during very early development and that the ß-Cyano-Alanine synthase/ß-Cyano-Alanine hydratase could be the pathway for Asn synthesis in "Dixiland" peach fruit. Additionally, photosynthetic machinery decays during early development in mesocarp and endocarp. Proteins related to photosynthesis are found to a higher extent in mesocarp than in endocarp. We conclude mesocarpic photosynthesis is possible to occur early on the development, first providing both carbon and reductive power and latter only reductive power. Together with proteomic, histological tests and anatomical analysis help to provide information about changes and differences in cells and cell-walls in both tissues. Collectively, this work represents the first approach in building protein databases during peach fruit development focusing on endocarp and mesocarp tissues and provides novel insights into the biology of peach fruit development preceding pit hardening.

RESUMEN

Severe droughts are predicted for the twenty-first century, which contrast with the increased demand for plant materials. Thus, to sustain future generations, a great challenge is to improve crop yield and water use efficiency (WUE), which is the carbon gained per water lost. Here, expression of maize NADP-malic enzyme (NADP-ME) in the guard and vascular companion cells of Nicotiana tabacum results in enhanced WUE, earlier flowering and shorter life cycle. Transgenic lines exhibit reduced stomatal aperture than wild-type (WT). Nevertheless, an increased net CO2 fixation rate is observed, which results in less water consumption and more biomass production per water used. Transgenic lines export sugars to the phloem at higher rate than WT, which leads to higher sugars levels in phloem exudates and veins. Leaf quantitative proteomic profiling revealed drastic differences in proteins related to cell cycle, flowering, hormone signaling and carbon metabolism between transgenic lines and WT. We propose that the increased sugar export from leaves in the transgenic lines alleviates sugar negative feedback on photosynthesis and thus, stomatal closure takes place without a penalty in CO2 assimilation rate. This results in improved WUE and accelerated overall life cycle, key traits for plant productivity in the near future world.

Asunto(s)

Deshidratación/prevención & control , Malato Deshidrogenasa/metabolismo , Nicotiana/fisiología , Plantas Modificadas Genéticamente/metabolismo , Dióxido de Carbono/metabolismo , Sequías , Estadios del Ciclo de Vida , Hojas de la Planta/metabolismo , Estomas de Plantas , Proteómica/métodos , Nicotiana/citología

RESUMEN

Peaches ripen and deteriorate rapidly at room temperature. Therefore, refrigeration is used to slow these processes and to extend fruit market life; however, many fruits develop chilling injury (CI) during storage at low temperature. Given that cell membranes are likely sites of the primary effects of chilling, the lipidome of six peach varieties with different susceptibility to CI was analyzed under different postharvest conditions. By using liquid chromatography coupled to mass spectrometry (LC-MS), 59 lipid species were detected, including diacyl- and triacylglycerides. The decreases in fruit firmness during postharvest ripening were accompanied by changes in the relative amount of several plastidic glycerolipid and triacylglyceride species, which may indicate their use as fuels prior to fruit senescence. In addition, levels of galactolipids were also modified in fruits stored at 0°C for short and long periods, reflecting the stabilization of plastidic membranes at low temperature. When comparing susceptible and resistant varieties, the relative abundance of certain species of the lipid classes phosphatidylethanolamine, phosphatidylcholine and digalactosyldiacylglycerol correlated with the tolerance to CI, reflecting the importance of the plasma membrane in the development of CI symptoms and allowing the identification of possible lipid markers for chilling resistance. Finally, transcriptional analysis of genes involved in galactolipid metabolism revealed candidate genes responsible for the observed changes after cold exposure. When taken together, our results highlight the importance of plastids in the postharvest physiology of fruits and provide evidence that lipid composition and metabolism have a profound influence on the cold response.

Asunto(s)

Frutas/fisiología , Lípidos/análisis , Prunus persica/fisiología , Cromatografía Liquida , Frío , Almacenamiento de Alimentos , Plastidios , Espectrometría de Masas en Tándem

RESUMEN

The worldwide-distributed leaf peach curl disease is caused by the biotroph Taphrina deformans. To characterize the plant-fungus interaction, resistant and susceptible Prunus persica genotypes grown in the orchard were studied. Asymptomatic leaves were tested for fungal presence. In all resistant leaves analyzed the fungus was not detected. Conversely, leaves from the susceptible genotype were categorized according to the presence or absence of the pathogen. Comparative metabolomic analysis disclosed the metabolite composition associated with resistant and susceptible interactions, and of compounds involved in fungal growth inhibition such as chlorogenic acid, whose in vitro antifungal activity was verified in this work. Differential proteome studies revealed that chloroplasts are important site of plant defense responses against T. deformans. Members of the Bet-v1-like family protein differentially responded to the pathogen. Extracellular pathogenesis-related proteins, evaluated by qRT-PCR, and an enone oxidoreductase are constitutively present in leaves of resistant trees and could be related to fungal resistance. This study is a global view of the changes in the metabolome, proteome and transcripts related to plant defense in naturally infected leaves of susceptible plants during the asymptomatic stage. Additionally, it provides clues to the successful molecular mechanisms operating in resistant plants, which neither develop the disease nor harbor the pathogen.

Asunto(s)

Ascomicetos , Resistencia a la Enfermedad/genética , Genotipo , Metaboloma/genética , Proteoma , Prunus persica , Proteoma/genética , Proteoma/metabolismo , Proteómica , Prunus persica/genética , Prunus persica/metabolismo , Prunus persica/microbiología

RESUMEN

Leaf peach curl is a devastating disease affecting leaves, flowers and fruits, caused by the dimorphic fungus Taphrina deformans. To gain insight into the mechanisms of fungus pathogenesis and plant responses, leaves of a resistant and two susceptible Prunus persica genotypes were inoculated with blastospores (yeast), and the infection was monitored during 120 h post inoculation (h.p.i.). Fungal dimorphism to the filamentous form and induction of reactive oxygen species (ROS), callose synthesis, cell death and defence compound production were observed independently of the genotype. Fungal load significantly decreased after 120 h.p.i. in the resistant genotype, while the pathogen tended to grow in the susceptible genotypes. Metabolic profiling revealed a biphasic re-programming of plant tissue in susceptible genotypes, with an initial stage co-incident with the yeast form of the fungus and a second when the hypha is developed. Transcriptional analysis of PRs and plant hormone-related genes indicated that pathogenesis-related (PR) proteins are involved in P. persica defence responses against T. deformans and that salicylic acid is induced in the resistant genotype. Conducted experiments allowed the elucidation of common and differential responses in susceptible versus resistant genotypes and thus allow us to construct a picture of early events during T. deformans infection.

Asunto(s)

Ascomicetos/fisiología , Resistencia a la Enfermedad/genética , Interacciones Huésped-Patógeno , Enfermedades de las Plantas/microbiología , Prunus persica/genética , Prunus persica/microbiología , Susceptibilidad a Enfermedades , Regulación de la Expresión Génica de las Plantas , Genotipo , Metaboloma , Metabolómica , Modelos Biológicos , Pigmentos Biológicos/metabolismo , Hojas de la Planta/metabolismo , Hojas de la Planta/microbiología , Análisis de Componente Principal , Prunus persica/inmunología , ARN Mensajero/genética , ARN Mensajero/metabolismo

RESUMEN

Reconfiguration of the metabolome is a key component involved in the acclimation to cold in plants; however, few studies have been devoted to the analysis of the overall metabolite changes after cold storage of fruits prior to consumption. Here, metabolite profiling of six peach varieties with differential susceptibility to develop mealiness, a chilling-injury (CI) symptom, was performed. According to metabolic content at harvest; after cold treatment; and after ripening, either following cold treatment or not; peach fruits clustered in distinct groups, depending on harvest-time, cold treatment, and ripening state. Both common and distinct metabolic responses among the six varieties were found; common changes including dramatic galactinol and raffinose rise; GABA, Asp, and Phe increase; and 2-oxo-glutarate and succinate decrease. Raffinose content after long cold treatment quantitatively correlated to the degree of mealiness resistance of the different peach varieties; and thus, raffinose emerges as a candidate biomarker of this CI disorder. Xylose increase after cold treatment was found only in the susceptible genotypes, indicating a particular cell wall reconfiguration of these varieties while being cold-stored. Overall, results indicate that peach fruit differential metabolic rearrangements due to cold treatment, rather than differential metabolic priming before cold, are better related with CI resistance. The plasticity of peach fruit metabolism renders it possible to induce a diverse metabolite array after cold, which is successful, in some genotypes, to avoid CI.

RESUMEN

KEY MESSAGE: The results obtained indicate that a ß-xylosidase gene may act as good indicator of chilling tolerance and provide new insights into the complex issue of peach fruit woolliness. The storage of peaches at low temperatures for prolonged periods can induce a form of chilling injury (CI) called woolliness, characterized by a lack of juiciness and a mealy texture. As this disorder has been associated with abnormal cell wall dismantling, the levels of 12 transcripts encoding proteins involved in cell wall metabolism were analysed in cultivars with contrasting susceptibility to this disorder selected from five melting flesh peach cultivars. The resistant ('Springlady') and susceptible ('Flordaking') cultivars displayed differences in the level of expression of some of the selected genes during fruit softening and in woolly versus non-woolly fruits. From these genes, the level of expression of PpXyl, which encodes for a putative ß-xylosidase, was the one that presented the highest correlation (negative) with the susceptibility to woolliness. PpXyl expression was also analysed in a cultivar ('Rojo 2') with intermediate susceptibility to woolliness, reinforcing the conclusion about the correlation of PpXyl expression to the presence of woolliness symptom. Moreover, the level of expression of PpXyl correlated to protein level detected by Western blot. Analyses of the promoter region of the PpXyl gene (1637 bp) isolated from the three cultivars showed no differences suggesting that cis-elements from other regions of the genome and/or trans elements could be responsible of the differential PpXyl expression patterns. Overall, the results obtained indicate that PpXyl may act as a good indicator of woolliness tolerance and that the regulation of expression of this gene in different cultivars does not depend on sequences upstream the coding sequence.

Asunto(s)

Pared Celular/genética , Frutas/genética , Prunus persica/genética , Frío , Electroforesis en Gel de Poliacrilamida , Almacenamiento de Alimentos , Frutas/fisiología , Prunus persica/fisiología , Carácter Cuantitativo Heredable , Reacción en Cadena en Tiempo Real de la Polimerasa

RESUMEN

Peach (Prunus persica) fruits from different varieties display differential organoleptic and nutritional properties, characteristics related to their chemical composition. Here, chemical biodiversity of peach fruits from fifteen varieties, at harvest and after post-harvest ripening, was explored by gas chromatography-mass spectrometry. Metabolic profiling revealed that metabolites involved in organoleptic properties (sugars, organic and amino acids), stress tolerance (raffinose, galactinol, maltitol), and with nutritional properties (amino, caffeoylquinic and dehydroascorbic acids) displayed variety-dependent levels. Peach varieties clustered into four groups: two groups of early-harvest varieties with higher amino acid levels; two groups of mid- and late-harvest varieties with higher maltose levels. Further separation was mostly dependent on organic acids/raffinose levels. Variety-dependent and independent metabolic changes associated with ripening were detected; which contribute to chemical diversity or can be used as ripening markers, respectively. The great variety-dependent diversity in the content of metabolites that define fruit quality reinforces metabolomics usage as a tool to assist fruit quality improvement in peach.

Asunto(s)

Frutas/química , Prunus persica/química , Cromatografía de Gases y Espectrometría de Masas , Metabolómica

RESUMEN

Peaches are highly perishable and deteriorate quickly at ambient temperature. Cold storage is commonly used to prevent fruit decay; however, it affects fruit quality causing physiological disorders collectively termed 'chilling injury' (CI). To prevent or ameliorate CI, heat treatment is often applied prior to cold storage. In the present work, metabolic profiling was performed to determine the metabolic dynamics associated with the induction of acquired CI tolerance in response to heat shock. 'Dixiland' peach fruits exposed to 39 °C, cold stored, or after a combined treatment of heat and cold, were compared with fruits ripening at 20 °C. Dramatic changes in the levels of compatible solutes such as galactinol and raffinose were observed, while amino acid precursors of the phenylpropanoid pathway were also modified due to the stress treatments, as was the polyamine putrescine. The observed responses towards temperature stress in peaches are composed of both common and specific response mechanisms to heat and cold, but also of more general adaptive responses that confer strategic advantages in adverse conditions such as biotic stresses. The identification of such key metabolites, which prime the fruit to cope with different stress situations, will likely greatly accelerate the design and the improvement of plant breeding programs.

Asunto(s)

Frío , Frutas/metabolismo , Frutas/fisiología , Calor , Redes y Vías Metabólicas , Prunus/metabolismo , Prunus/fisiología , Frutas/genética , Cromatografía de Gases y Espectrometría de Masas , Regulación de la Expresión Génica de las Plantas , Redes y Vías Metabólicas/genética , Metaboloma/genética , Metabolómica , Nitrógeno/metabolismo , Análisis de Componente Principal , Prunus/genética , Carácter Cuantitativo Heredable , ARN Mensajero/genética , ARN Mensajero/metabolismo , Rafinosa/metabolismo

RESUMEN

Cold storage is extensively used to slow the rapid deterioration of peach (Prunus persica L. Batsch) fruit after harvest. However, peach fruit subjected to long periods of cold storage develop chilling injury (CI) symptoms. Post-harvest heat treatment (HT) of peach fruit prior to cold storage is effective in reducing some CI symptoms, maintaining fruit quality, preventing softening and controlling post-harvest diseases. To identify the molecular changes induced by HT, which may be associated to CI protection, the differential transcriptome of peach fruit subjected to HT was characterized by the differential display technique. A total of 127 differentially expressed unigenes (DEUs), with a presence-absence pattern, were identified comparing peach fruit ripening at 20°C with those exposed to a 39°C-HT for 3 days. The 127 DEUs were divided into four expression profile clusters, among which the heat-induced (47%) and heat-repressed (36%) groups resulted the most represented, including genes with unknown function, or involved in protein modification, transcription or RNA metabolism. Considering the CI-protection induced by HT, 23-heat-responsive genes were selected and analyzed during and after short-term cold storage of peach fruit. More than 90% of the genes selected resulted modified by cold, from which nearly 60% followed the same and nearly 40% opposite response to heat and cold. Moreover, by using available Arabidopsis microarray data, it was found that nearly 70% of the peach-heat responsive genes also respond to cold in Arabidopsis, either following the same trend or showing an opposite response. Overall, the high number of common responsive genes to heat and cold identified in the present work indicates that HT of peach fruit after harvest induces a cold response involving complex cellular processes; identifying genes that are involved in the better preparation of peach fruit for cold-storage and unraveling the basis for the CI protection induced by HT.

Asunto(s)

Frutas/genética , Regulación de la Expresión Génica de las Plantas , Prunus/genética , Transcriptoma , Frío , Frutas/metabolismo , Perfilación de la Expresión Génica , Calor , Prunus/metabolismo

RESUMEN

Ripening of peach (Prunus persica L. Batsch) fruit is accompanied by dramatic cell wall changes that lead to softening. Post-harvest heat treatment is effective in delaying softening and preventing some chilling injury symptoms that this fruit exhibits after storage at low temperatures. In the present work, the levels of twelve transcripts encoding proteins involved in cell wall metabolism, as well as the differential extracellular proteome, were examined after a post-harvest heat treatment (HT; 39 °C for 3 days) of "Dixiland" peach fruit. A typical softening behaviour, in correlation with an increase in 1-aminocyclopropane-1-carboxylic acid oxidase-1 (PpACO1), was observed for peach maintained at 20 °C for 3 days (R3). Six transcripts encoding proteins involved in cell wall metabolism significantly increased in R3 with respect to peach at harvest, while six showed no modification or even decreased. In contrast, after HT, fruit maintained their firmness, exhibiting low PpACO1 level and significant lower levels of the twelve cell wall-modifying genes than in R3. Differential proteomic analysis of apoplastic proteins during softening and after HT revealed a significant decrease of DUF642 proteins after HT; as well as an increase of glyceraldehyde-3-phosphate dehydrogenase (GAPC) after softening. The presence of GAPC in the peach extracellular matrix was further confirmed by in situ immunolocalization and transient expression in tomato fruit. Though further studies are required to establish the function of DUF642 and GAPC in the apoplast, this study contributes to a deeper understanding of the events during peach softening and after HT with a focus on this key compartment.

Asunto(s)

Espacio Extracelular/metabolismo , Frutas/metabolismo , Proteínas de Plantas/metabolismo , Proteoma , Prunus/metabolismo , Aminoácido Oxidorreductasas/genética , Aminoácido Oxidorreductasas/metabolismo , Pared Celular/metabolismo , Regulación hacia Abajo , Electroforesis en Gel Bidimensional , Frutas/citología , Frutas/enzimología , Frutas/genética , Expresión Génica , Regulación de la Expresión Génica de las Plantas , Gliceraldehído-3-Fosfato Deshidrogenasas/genética , Gliceraldehído-3-Fosfato Deshidrogenasas/metabolismo , Calor , Solanum lycopersicum/citología , Solanum lycopersicum/enzimología , Solanum lycopersicum/genética , Solanum lycopersicum/metabolismo , Fenotipo , Proteínas de Plantas/genética , Proteómica , Prunus/citología , Prunus/enzimología , Prunus/genética , ARN Mensajero/genética , ARN de Planta/genética , Espectrometría de Masas en Tándem , Regulación hacia Arriba

RESUMEN

Fruit from rosaceous species collectively display a great variety of flavors and textures as well as a generally high content of nutritionally beneficial metabolites. However, relatively little analysis of metabolic networks in rosaceous fruit has been reported. Among rosaceous species, peach (Prunus persica) has stone fruits composed of a juicy mesocarp and lignified endocarp. Here, peach mesocarp metabolic networks were studied across development using metabolomics and analysis of key regulatory enzymes. Principal component analysis of peach metabolic composition revealed clear metabolic shifts from early through late development stages and subsequently during postharvest ripening. Early developmental stages were characterized by a substantial decrease in protein abundance and high levels of bioactive polyphenols and amino acids, which are substrates for the phenylpropanoid and lignin pathways during stone hardening. Sucrose levels showed a large increase during development, reflecting translocation from the leaf, while the importance of galactinol and raffinose is also inferred. Our study further suggests that posttranscriptional mechanisms are key for metabolic regulation at early stages. In contrast to early developmental stages, a decrease in amino acid levels is coupled to an induction of transcripts encoding amino acid and organic acid catabolic enzymes during ripening. These data are consistent with the mobilization of amino acids to support respiration. In addition, sucrose cycling, suggested by the parallel increase of transcripts encoding sucrose degradative and synthetic enzymes, appears to operate during postharvest ripening. When taken together, these data highlight singular metabolic programs for peach development and may allow the identification of key factors related to agronomic traits of this important crop species.

Asunto(s)

Frutas/crecimiento & desarrollo , Regulación de la Expresión Génica de las Plantas/fisiología , Metaboloma , Proteínas de Plantas/metabolismo , Prunus/crecimiento & desarrollo , Prunus/metabolismo , Aminoácidos/análisis , Aminoácidos/metabolismo , Transporte Biológico , Ácidos Carboxílicos/análisis , Ácidos Carboxílicos/metabolismo , Disacáridos/análisis , Disacáridos/metabolismo , Enzimas/genética , Enzimas/metabolismo , Frutas/enzimología , Frutas/genética , Frutas/metabolismo , Cromatografía de Gases y Espectrometría de Masas , Regulación Enzimológica de la Expresión Génica/fisiología , Redes y Vías Metabólicas , Hojas de la Planta/enzimología , Hojas de la Planta/genética , Hojas de la Planta/crecimiento & desarrollo , Hojas de la Planta/metabolismo , Proteínas de Plantas/genética , Polifenoles/análisis , Polifenoles/metabolismo , Análisis de Componente Principal , Prunus/enzimología , Prunus/genética , Rafinosa/análisis , Rafinosa/metabolismo , Sacarosa/análisis , Sacarosa/metabolismo , Alcoholes del Azúcar/análisis , Alcoholes del Azúcar/metabolismo

RESUMEN

The use of modified atmospheres has been successfully applied in different fruits to delay the ripening process and to prevent physiological disorders. In addition, during normal ripening, hypoxic areas are generated inside the fruit; moreover, anaerobic conditions may also arise during fruit post-harvest storage and handling. In consequence, the fruit is an interesting model to analyze the metabolic modifications due to changes in oxygen levels. In this work, a 72 h anoxic treatment by using an N(2) storage atmosphere was applied to peaches (Prunus persica L. Batsch) after harvest. Ripening was effectively delayed in treated fruits, preventing fruit softening, color changes and ethylene production. Metabolic changes induced by anoxia included induction of fermentative pathways, glycolysis and enzymes involved in both sucrose synthesis and degradation. Sucrose, fructose and glucose contents remained unchanged in treated fruit, probably due to sucrose cycling. Sorbitol was not consumed and citrate was increased, correlating with citric acid cycle impairment due to O(2) deprivation. Malate content was not affected, indicating compensation in the reactions producing and consuming malate. Changes in malic enzymes and pyruvate orthophosphate dikinase may provide pyruvate for fermentation or even act to regenerate NADP. After fruit transfer to aerobic conditions, no signs of post-anoxia injury were observed and metabolic changes were reversed, with the exception of acetaldehyde levels. The results obtained indicate that peach fruit is an organ with a high capacity for anoxic tolerance, which is in accord with the presence of hypoxic areas inside fruits and the fact that hypoxic pre-treatment improves tolerance to subsequent anoxia.

Asunto(s)

Frutas/fisiología , Prunus/fisiología , Anaerobiosis , Metabolismo de los Hidratos de Carbono , Hipoxia de la Célula , Etilenos/biosíntesis , Fermentación , Frutas/enzimología , Frutas/genética , Oxígeno/química , Prunus/enzimología , Prunus/genética , ARN de Planta/genética , Sacarosa/metabolismo

RESUMEN

Shipping of peaches to distant markets and storage require low temperature; however, cold storage affects fruit quality causing physiological disorders collectively termed 'chilling injury' (CI). In order to ameliorate CI, different strategies have been applied before cold storage; among them heat treatment (HT) has been widely used. In this work, the effect of HT on peach fruit quality as well as on carbon metabolism was evaluated. When fruit were exposed to 39 degrees C for 3 d, ripening was delayed, with softening inhibition and slowing down of ethylene production. Several differences were observed between fruit ripening at ambient temperature versus fruit that had been heat treated. However, the major effects of HT on carbon metabolism and organoleptic characteristics were reversible, since normal fruit ripening was restored after transferring heated peaches to ambient temperature. Positive quality features such as an increment in the fructose content, largely responsible for the sweetness, and reddish coloration were observed. Nevertheless, high amounts of acetaldehyde and low organic acid content were also detected. The differential proteome of heated fruit was characterized, revealing that heat-induced CI tolerance may be acquired by the activation of different molecular mechanisms. Induction of related stress proteins in the heat-exposed fruits such as heat shock proteins, cysteine proteases, and dehydrin, and repression of a polyphenol oxidase provide molecular evidence of candidate proteins that may prevent some of the CI symptoms. This study contributes to a deeper understanding of the cellular events in peach under HT in view of a possible technological use aimed to improve organoleptic and shelf-life features.

Asunto(s)

Frutas/genética , Proteómica , Prunus/genética , Electroforesis en Gel Bidimensional , Etilenos/metabolismo , Frutas/química , Frutas/metabolismo , Regulación de la Expresión Génica de las Plantas , Calor , Proteínas de Plantas/química , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Prunus/química , Prunus/metabolismo

RESUMEN

Peach (Prunus persica L. Batsch) is a climacteric fruit that ripens after harvest, prior to human consumption. Organic acids and soluble sugars contribute to the overall organoleptic quality of fresh peach; thus, the integrated study of the metabolic pathways controlling the levels of these compounds is of great relevance. Therefore, in this work, several metabolites and enzymes involved in carbon metabolism were analysed during the post-harvest ripening of peach fruit cv 'Dixiland'. Depending on the enzyme studied, activity, protein level by western blot, or transcript level by quantitative real time-PCR were analysed. Even though sorbitol did not accumulate at a high level in relation to sucrose at harvest, it was rapidly consumed once the fruit was separated from the tree. During the ripening process, sucrose degradation was accompanied by an increase of glucose and fructose. Specific transcripts encoding neutral invertases (NIs) were up-regulated or down-regulated, indicating differential functions for each putative NI isoform. Phosphoenolpyruvate carboxylase was markedly induced, and may participate as a glycolytic shunt, since the malate level did not increase during post-harvest ripening. The fermentative pathway was highly induced, with increases in both the acetaldehyde level and the enzymes involved in this process. In addition, proteins differentially expressed during the post-harvest ripening process were also analysed. Overall, the present study identified enzymes and pathways operating during the post-harvest ripening of peach fruit, which may contribute to further identification of varieties with altered levels of enzymes/metabolites or in the evaluation of post-harvest treatments to produce fruit of better organoleptic attributes.

Asunto(s)

Metabolismo de los Hidratos de Carbono , Compuestos Orgánicos/metabolismo , Proteínas de Plantas/metabolismo , Prunus/enzimología , Frutas/metabolismo , Proteínas de Plantas/genética , Proteoma/genética , Proteoma/metabolismo , Prunus/genética , Prunus/metabolismo

RESUMEN

Different preparations of antibodies against 62 kDa NADP-malic enzyme (NADP-ME) from purified maize leaves cross-react with a 72 kDa protein from diverse tissues in many species. A 72 kDa protein, suggested to be a non-photosynthetic NADP-ME, has been purified from several plant species. However, to date, a cDNA coding for this putative 72 kDa NADP-ME has not been isolated. The screening of maize and tobacco leaf expression libraries using antibodies against purified 62 kDa NADP-ME allowed the identification of a heat shock protein (Hsp70). In addition, tandem mass spectrometry (MS/MS) studies indicate that along with NADP-ME, a 72 kDa protein, identified as an Hsp70 and reacting with the antibodies, is also purified from maize roots. On the other hand, the screening of a maize root cDNA library revealed the existence of a cDNA that encodes a mature 66 kDa NADP-ME. These results suggest that the 72 kDa protein is not actually an NADP-ME but in fact an Hsp70, at least in maize and tobacco. Probably, NADP-ME-Hsp70 association, taking place at least when preparing crude extracts, can lead to a co-purification of the proteins and can thus explain the cross-reaction of the antibodies. In the present work, we analyse and discuss a probable interaction of NADP-ME with Hsp70.

Asunto(s)

Proteínas HSP70 de Choque Térmico/aislamiento & purificación , Malato Deshidrogenasa/aislamiento & purificación , Proteínas de Plantas/aislamiento & purificación , Secuencia de Aminoácidos , Secuencia de Bases , Reacciones Cruzadas , ADN Complementario/genética , ADN de Plantas/genética , Estabilidad de Enzimas , Biblioteca de Genes , Proteínas Fluorescentes Verdes/genética , Proteínas Fluorescentes Verdes/metabolismo , Proteínas HSP70 de Choque Térmico/genética , Proteínas HSP70 de Choque Térmico/inmunología , Proteínas HSP70 de Choque Térmico/metabolismo , Cinética , Malato Deshidrogenasa/genética , Malato Deshidrogenasa/inmunología , Malato Deshidrogenasa/metabolismo , Datos de Secuencia Molecular , Proteínas de Plantas/genética , Proteínas de Plantas/inmunología , Proteínas de Plantas/metabolismo , Plantas Modificadas Genéticamente , Proteínas Recombinantes de Fusión/genética , Proteínas Recombinantes de Fusión/aislamiento & purificación , Proteínas Recombinantes de Fusión/metabolismo , Nicotiana/genética , Nicotiana/metabolismo , Zea mays/genética , Zea mays/metabolismo

RESUMEN

The C(4) succulent plant Portulaca oleracea shifts its photosynthetic metabolism to crassulacean acid metabolism (CAM) after 23 d of withholding water. This is accounted by diurnal acid fluctuation, net nocturnal but not day CO(2) uptake and drastic changes in phosphoenolpyruvate carboxylase (PEPC) kinetic and regulatory properties [Lara et al. (2003) Photosynth: Res. 77: 241]. The goal of the present work was to characterize the CAM activity in leaves of P. oleracea during water stress through the study of enzymes involved in carbon fixation and carbohydrate metabolism. After drought stress, a general decrease in the photosynthetic metabolism, as accounted by the decrease in the net CO(2) fixation and in the activity of enzymes such as ribulose-1,5-bisphosphate carboxylase/oxygenase, PEPC, pyruvate orthophosphate dikinase, phosphoenolpyruvate carboxykinase and NAD-malic enzyme was observed. We also found changes in the day/night activities and level of immunoreactive protein of some of these enzymes which were correlated to night CO(2) fixation, as occurs under CAM metabolism. Based on the results obtained, including those from in situ immunolocalization studies, we propose a scheme for the possible CO(2) fixation pathways used by P. oleracea under conditions of sufficient and limiting water supply.

Asunto(s)

Metabolismo de los Hidratos de Carbono , Carbono/metabolismo , Fotosíntesis/fisiología , Portulaca/enzimología , Ritmo Circadiano/fisiología , Oscuridad , Deshidratación , Desastres , Regulación hacia Abajo/fisiología , Malato Deshidrogenasa/metabolismo , Fosfoenolpiruvato Carboxiquinasa (ATP)/metabolismo , Hojas de la Planta/metabolismo , Proteínas Serina-Treonina Quinasas/metabolismo , Piruvato Ortofosfato Diquinasa/metabolismo , Ribulosa-Bifosfato Carboxilasa/metabolismo