Browsing by Author "Serrano Canales, Alejandra Rita de Lourdes"

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    An update on sugar transport and signalling in grapevine
    (2014) Lecourieux, F.; Serrano Canales, Alejandra Rita de Lourdes; Arce Johnson, Jorge Patricio
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    Participación de glucosa en el proceso de maduración del fruto de vitis vinifera, a través de la regulación de la biosíntesis de antocianinas y el transporte polar de auxina.
    (2014) Serrano Canales, Alejandra Rita de Lourdes; Arce Johnson, Jorge Patricio; Pontificia Universidad Católica de Chile. Facultad de Ciencias Biológicas
    El desarrollo del fruto de vid, baya carnosa derivada del ovario de la flor, puede dividirse en tres etapas, dentro de las cuales ocurre una serie de cambios fisiológicos y bioquímicos que permiten al fruto acumular diferentes solutos y diferenciarse en distintos tejidos tales como piel, pulpa y semilla. La etapa I es un periodo de formación y se caracteriza por tener una elevada tasa de expansión y división celular que permite el aumento exponencial del tamaño del fruto y también establecer el número total de células que formarán parte de él. En la etapa II no hay incremento del tamaño, sin embargo hacia el final de esta ocurre un aumento exponencial de glucosa y fructosa, principales azúcares que forman parte del fruto. Coincidentemente, en este mismo periodo del desarrollo en el cual comienza la acumulación de estas hexosas, se inicia la síntesis de antocianinas, metabolitos secundarios pertenecientes al grupo de los flavonoides, que otorgan coloración a las bayas de variedades tinta. Este momento se conoce como pinta y marca el inicio de la etapa III o maduración.
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    Regulation of polar auxin transport in grapevine fruitlets (Vitis vinifera L.) and the proposed role of auxin homeostasis during fruit abscission
    (2016) Kühn Weber, Nathalie Alexandra; Serrano Canales, Alejandra Rita de Lourdes; Abello, Carlos; Arce Medina, Aníbal Andrés; Espinoza Cancino, Carmen Gloria; Gouthu, Satyanarayana; Deluc, Laurent; Arce Johnson, Jorge Patricio
    Background Indole-3-acetic acid (IAA), the most abundant auxin, is a growth promoter hormone involved in several developmental processes. Auxin homeostasis is very important to its function and this is achieved through the regulation of IAA biosynthesis, conjugation, degradation and transport. In grapevine, IAA plays an essential role during initial stages of berry development, since it delays fruitlet abscission by reducing the ethylene sensitivity in the abscission zone. For this reason, Continuous polar IAA transport to the pedicel is required. This kind of transport is controlled by IAA, which regulates its own movement by modifying the expression and localization of PIN-FORMED (PIN) auxin efflux facilitators that localize asymmetrically within the cell. On the other hand, the hormone gibberellin (GA) also activates the polar auxin transport by increasing PIN stability. In Vitis vinifera, fruitlet abscission occurs during the first two to three weeks after flowering. During this time, IAA and GA are present, however the role of these hormones in the control of polar auxin transport is unknown. Results In this work, the use of radiolabeled IAA showed that auxin is basipetally transported during grapevine fruitlet abscission. This observation was further supported by immunolocalization of putative VvPIN proteins that display a basipetal distribution in pericarp cells. Polar auxin transport and transcripts of four putative VvPIN genes decreased in conjunction with increased abscission, and the inhibition of polar auxin transport resulted in fruit drop. GA3 and IAA treatments reduced polar auxin transport, but only GA3 treatment decreased VvPIN transcript abundance. When GA biosynthesis was blocked, IAA was capable to increase polar auxin transport, suggesting that its effect depends on GA content. Finally, we observed significant changes in the content of several IAA-related compounds during the abscission period. Conclusions These results provide evidence that auxin homeostasis plays a central role during grapevine initial fruit development and that GA and IAA controls auxin homeostasis by reducing polar auxin transport.