Browsing by Author "Olmedo, Patricio"

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    Deciphering the behind blackspot exocarp disorder in avocado cv. Hass through a hormonal, transcriptional and metabolic integration approach
    (2024) Nunez-Lillo, Gerardo; Hernandez, Ignacia; Olmedo, Patricio; Ponce, Excequel; Arancibia-Guerra, Camila; Sepulveda, Laura; Carrasco-Pancorbo, Alegria; Beiro-Valenzuela, Maria Gemma; Carrera, Esther; Banos, Jorge; Campos, David; Meneses, Claudio; Pedreschi, Romina
    Avocado cv. Hass is an important sub-tropical crop with an increasing global demand. However, the avocado supply chain experiences significant fruit losses, particularly during the postharvest stage due to diseases and disorders that manifest after prolonged cold storage or the ready-to-eat stage. The blackspot exocarp disorder, which appears as brown or black blotches only after extended cold storage conditions, leads to substantial commercial losses for exported avocados. This research aimed to identify transcriptomic, metabolomic, and hormonal changes in avocado fruits affected by blackspot disorder, differentiating between the green and black exocarp tissues directly impacted by this physiological disorder. The results showed a correlation between the black-colored exocarp of blackspot affected fruits with high levels of gibberellins, cytokinins, jasmonic acid and salicylic acid hormones. Metabolically, these changes were accompanied by a high fatty acid content of oleate, palmitate and linoleate. Using a metabolic pathway reconstruction analysis, we integrated hormonal and metabolic data with transcriptomic information. This approach identified several genes involved in central carbon metabolism, long-chain fatty acid elongation, and jasmonate/salicylate biosynthesis pathways, as well as a possible accumulation of lignins due to a high expression of genes associated with the phenylpropanoid pathway in the black exocarp of blackspot-affected fruits. These findings suggest that blackspot disorder results from a combination of plant defense mechanisms triggered to strengthen the fruit exocarp tissue.
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    Metabolite Profiling Reveals the Effect of Cold Storage on Primary Metabolism in Nectarine Varieties with Contrasting Mealiness
    (2023) Olmedo, Patricio; Zepeda, Baltasar; Delgado-Rioseco, Joaquin; Leiva, Carol; Moreno, Adrian A.; Sagredo, Karen; Blanco-Herrera, Francisca; Pedreschi, Romina; Infante, Rodrigo; Meneses, Claudio; Campos-Vargas, Reinaldo
    Chilling injury is a physiological disorder caused by cold storage in peaches and nectarines. The main symptom of chilling injury is mealiness/wooliness, described as a lack of juice in fruit flesh. In this work, we studied two nectarine varieties (Andes Nec-2 and Andes Nec-3) with contrasting susceptibility to mealiness after cold storage. A non-targeted metabolomic analysis was conducted by GC-MS to understand if changes in metabolite abundance are associated with nectarine mealiness induced by cold storage. Multivariate analyses indicated that in unripe nectarines, cold storage promoted a higher accumulation of amino acids in both varieties. Interestingly, for ripe nectarines, cold storage induced an accumulation of fewer amino acids in both varieties and showed an increased abundance of sugars and organic acids. A pathway reconstruction of primary metabolism revealed that in ripe nectarines, cold storage disrupted metabolite abundance in sugar metabolism and the TCA cycle, leading to a differential accumulation of amino acids, organic acids, and sugars in mealy and juicy nectarines.
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    Metabolomic and biochemical analysis of mesocarp tissues from table grape berries with contrasting firmness reveals cell wall modifications associated to harvest and cold storage
    (2022) Balic, Ivan; Olmedo, Patricio; Zepeda, Baltasar; Rojas, Barbara; Ejsmentewicz, Troy; Barros, Miriam; Aguayo, Daniel; Moreno, Adrian A.; Pedreschi, Romina; Meneses, Claudio; Campos-Vargas, Reinaldo
    Tissue texture influences the grape berry consumers acceptance. We studied the biological differences between the inner and outer mesocarp tissues in hard and soft berries of table grapes cv NN107. Texture analysis revealed lower levels of firmness in the inner mesocarp as compared with the outer tissue. HPAEC-PAD analysis showed an increased abundance of cell wall monosaccharides in the inner mesocarp of harder berries at harvest. Immunohistochemical analysis displayed differences in homogalacturonan methylesterification and cell wall calcium between soft and hard berries. This last finding correlated with a differential abundance of calcium measured in the alcohol-insoluble residues (AIR) of the inner tissue of the hard berries. Analysis of abundance of polar metabolites suggested changes in cell wall carbon supply precursors, providing new clues in the identification of the biochemical factors that define the texture of the mesocarp of grape berries.
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    Proteomic and Low-Polar Metabolite Profiling Reveal Unique Dynamics in Fatty Acid Metabolism during Flower and Berry Development of Table Grapes
    (2023) Olmedo, Patricio; Vidal, Juan; Ponce, Excequel; Defilippi, Bruno G.; Perez-Donoso, Alonso G.; Meneses, Claudio; Carpentier, Sebastien; Pedreschi, Romina; Campos-Vargas, Reinaldo
    Grapevine development and ripening are complex processes that involve several biochemical pathways, including fatty acid and lipid metabolism. Fatty acids are essential components of lipids, which play crucial roles in fruit maturation and flavor development. However, the dynamics of fatty acid metabolism in grape flowers and berries are poorly understood. In this study, we present those dynamics and investigate the mechanisms of fatty acid homeostasis on 'Thompson Seedless' berries using metabolomic and proteomic analyses. Low-polar metabolite profiling indicated a higher abundance of fatty acids at the pre-flowering and pre-veraison stages. Proteomic analyses revealed that grape flowers and berries display unique profiles of proteins involved in fatty acid biosynthesis, triacylglycerol assembly, fatty acid beta-oxidation, and lipid signaling. These findings show, for the first time, that fatty acid metabolism also plays an important role in the development of non-oil-rich tissues, opening new perspectives about lipid function and its relation to berry quality.
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    Proteomic and metabolomic integration reveals the effects of pre-flowering cytokinin applications on central carbon metabolism in table grape berries
    (2023) Olmedo, Patricio; Nunez-Lillo, Gerardo; Vidal, Juan; Leiva, Carol; Rojas, Barbara; Sagredo, Karen; Arriagada, Cesar; Defilippi, Bruno G.; Perez-Donoso, Alonso G.; Meneses, Claudio; Carpentier, Sebastien; Pedreschi, Romina; Campos-Vargas, Reinaldo
    Consumers around the world prefer high quality table grapes. To achieve higher quality traits at ripening, grapevine producers apply different plant growth regulators. The synthetic cytokinin forchlorfenuron N- (2-chloro-4-pyridinyl)-N '-phenylurea (CPPU) is widely used, its effect on grape quality is poorly understood. We hypothesized that the use of CPPU in pre-flowering can lead to changes in the metabolism that affects grape quality at harvest. Therefore, we investigated the role of CPPU applications on the quality of grapes by inte-grating proteomics and metabolomics. CPPU-treated grapevines showed a significant increase in berry size and firmness. Proteomic analyses indicated that CPPU-treated berries accumulated enzymes associated with carbo-hydrate metabolism, glycolysis, and tricarboxylic acid (TCA) cycle at harvest. Metabolomic analyses showed shifts in the abundance of compounds associated with carbohydrate metabolism and TCA cycle in CPPU-treated grapes. These findings suggest that CPPU applications modulate central carbon metabolism, improving grape berry quality.