Examinando por Autor "Ejsmentewicz, Troy"

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    Comparative study of two table grape varieties with contrasting texture during cold storage
    (MDPI AG, 2015-03) Ejsmentewicz, Troy; Balic, Iván; Sanhueza, Dayan; Barria, Romina; Meneses, Claudio; Orellana, Ariel; Prieto, Humberto; Defilippi, Bruno G.; Campos-Vargas, Reinaldo
    Postharvest softening of grape berries is one of the main problems affecting grape quality during export. Cell wall disassembly, especially of pectin polysaccharides, has been commonly related to fruit softening, but its influence has been poorly studied in grapes during postharvest life. In order to better understand this process, the Thompson seedless (TS) variety, which has significantly decreased berry texture after prolonged cold storage, was compared to NN107, a new table grape variety with higher berry firmness. Biochemical analysis revealed a greater amount of calcium in the cell wall of the NN107 variety and less reduction of uronic acids than TS during cold storage. In addition, the activity of polygalacturonase was higher in TS than NN107 berries; meanwhile pectin methylesterase activity was similar in both varieties. Polysaccharide analysis using carbohydrate gel electrophoresis (PACE) suggests a differential pectin metabolism during prolonged cold storage. Results revealed lower pectin fragments in TS after 60 days of cold storage and shelf life (SL) compared to 30 days of cold storage and 30 + SL, while NN107 maintained the same fragment profile across all time points evaluated. Our results suggest that these important differences in cell wall metabolism during cold storage could be related to the differential berry firmness observed between these contrasting table grape varieties. © 2015 by the authors
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    Ítem
    UUAT1 is a golgi-localized UDP-uronic acid transporter that modulates the polysaccharide composition of arabidopsis seed mucilage
    (American Society of Plant Biologists, 2017) Saez-Aguayo, Susana; Rautengarten, Carsten; Temple, Henry; Sanhueza, Dayan; Ejsmentewicz, Troy; Sandoval-Ibañez, Omar; Doñas, Daniela; Parra-Rojas, Juan Pablo; Ebert, Berit; Lehner, Arnaud; Mollet, Jean-Claude; Dupree, Paul; Scheller, Henrik V.; Heazlewood, Joshua L.; Reyes, Francisca C.; Orellana, Ariel
    UDP-glucuronic acid (UDP-GlcA) is the precursor of many plant cell wall polysaccharides and is required for production of seed mucilage. Following synthesis in the cytosol, it is transported into the lumen of the Golgi apparatus, where it is converted to UDP-galacturonic acid (UDP-GalA), UDP-arabinose, and UDP-xylose. To identify the Golgi-localized UDP-GlcA transporter, we screened Arabidopsis thaliana mutants in genes coding for putative nucleotide sugar transporters for altered seed mucilage, a structure rich in the GalA-containing polysaccharide rhamnogalacturonan I. As a result, we identified UUAT1, which encodes a Golgi-localized protein that transports UDP-GlcA and UDP-GalA in vitro. The seed coat of uuat1 mutants had less GalA, rhamnose, and xylose in the soluble mucilage, and the distal cell walls had decreased arabinan content. Cell walls of other organs and cells had lower arabinose levels in roots and pollen tubes, but no differences were observed in GalA or xylose contents. Furthermore, the GlcA content of glucuronoxylan in the stem was not affected in the mutant. Interestingly, the degree of homogalacturonan methylation increased in uuat1. These results suggest that this UDP-GlcA transporter plays a key role defining the seed mucilage sugar composition and that its absence produces pleiotropic effects in this component of the plant extracellular matrix. © 2016 American Society of Plant Biologists.