CaracterizaciĆ³n de los componentes de la pared celular de uva de mesa "Thompson Seedless" en estadios tempranos de desarrollo y su relaciĆ³n con la firmeza en cosecha y postcosecha
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2019
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es
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Universidad AndrƩs Bello
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Resumen
Vitis vinifera es una de las especies de plantas frutales mƔs importantes en el
mundo. La uva de mesa es la fruta fresca mƔs exportada en Chile, siendo la variedad
Thompson Seedless una de las mĆ”s relevantes dentro de los mĆŗltiples cultivares
producidos en nuestro paĆs. La exportaciĆ³n de este producto a los mercados
extranjeros conlleva grandes desafĆos debido a las distancias y por consecuencia, al
tiempo de transporte involucrado, el cual afecta directamente su calidad debido a los
distintos procesos metabĆ³licos que permanecen activos, aĆŗn incluso durante su
almacenamiento en frĆo. Uno de los atributos mĆ”s afectado corresponde a la firmeza de
la baya, el cual es uno de los parƔmetros mƔs apreciados por el consumidor, no
obstante, la variedad Thompson Seedless presenta problemas para mantener estas
caracterĆsticas durante postcosecha. Esta disminuciĆ³n en la firmeza se ha asociado al
desensamble de la pared celular en diversos tipos de berries, sin embargo, los
antecedentes disponibles no consideran las modificaciones que presenta esta
estructura durante los puntos previos a pinta. En el presente estudio se sugiere que los
distintos componentes de la pared celular se encuentran asociados a la firmeza del
fruto y deben ser analizados en su conjunto debido a las grandes variaciones
fenotĆpicas y moleculares que presenta la uva de mesa durante todo su desarrollo.
Nuestros resultados sugieren que la disminuciĆ³n de textura en las bayas se encuentra
directamente asociada al aumento del epĆtopo disponible, correspondiente a las
ramificaciones del ramnogalacturonano I y a la configuraciĆ³n XXXG presente en las
cadenas de hemicelulosa, observado mediante un anƔlisis inmunologico in muro. Los
anƔlisis enzimƔticos en la totalidad del fruto muestran una elevada actividad de las
enzimas (3-Galactosidasa y Poligalacturonasa encargadas del remodelamiento de la
pared, principalmente en los estadios tempranos del desarrollo; observando una
correlaciĆ³n entre esta actividad y la expresiĆ³n de los genes correspondientes a estas
enzimas durante las primeras semanas post-antesis del fruto. Nuestros resultados
sugieren que el ablandamiento se debe a la degradaciĆ³n de los distintos componentes
de la pared celular, donde el aumento de pectinas y hemicelulosas en las fases solubles
del fraccionamiento de la pared presenta la mayor correlaciĆ³n con el parĆ”metro de
firmeza durante la cosecha del fruto.
Vitis vinifera is one of the most important fruit species in the world. The table grape is the most exported fresh fruit in Chile, being the Thompson Seedless variety quite relevant among the multiple cultivars produced in our country. The export of table grapes to foreign markets entails great challenges due to the distances and consequently, the transport time involved, which directly affects its quality due to the different metabolic processes in action, even during cold storage. One of the most affected attributes corresponds to the firmness of the berry, which is one of the parameters most highlighted by the consumer. However, the Thompson Seedless variety presents problems to maintain these characteristics during postharvest. This decrease in firmness has been associated with the disassembly of the cell wall in different types of berries, however, the available information does not consider the modifications that this structure presents during the points prior to veraison. It is for this reason that in the present study different physiological, biochemical and molecular factors were analyzed. It was suggested that the different components of the cell wall are associated to the firmness of the fruit and must be analyzed as a whole due to the great phenotypic and molecular variations that the table grape presents during all its development, mainly in its early stages. Our results suggest that the decrease of texture in the berries is directly associated with the increase of the available epitope, corresponding to the ramifications of rhamnogalacturonan I and to the XXXG configuration in the chains of hemicellulose in the cell wall, observed by means of an immunohistochemical analysis. Enzymatic studies in the whole fruit show a high activity of the enzymes (3-Galactosidase and polygalacturonase in charge of wall remodeling, mainly in the early stages of development; observing a correlation between this activity and the expression of the genes corresponding to these enzymes during the first weeks post-anthesis of the fruit. In addition, there is an increase in the soluble elements of the wall correlated with a decrease in the firmness of the fruit after veraison. Therefore, our results suggest that the softening is due to the degradation of the different components of the cell wall, where the increase of pectins and hemicellulose in the first phases of wall fractionation presents the highest correlation with the firmness parameter.
Vitis vinifera is one of the most important fruit species in the world. The table grape is the most exported fresh fruit in Chile, being the Thompson Seedless variety quite relevant among the multiple cultivars produced in our country. The export of table grapes to foreign markets entails great challenges due to the distances and consequently, the transport time involved, which directly affects its quality due to the different metabolic processes in action, even during cold storage. One of the most affected attributes corresponds to the firmness of the berry, which is one of the parameters most highlighted by the consumer. However, the Thompson Seedless variety presents problems to maintain these characteristics during postharvest. This decrease in firmness has been associated with the disassembly of the cell wall in different types of berries, however, the available information does not consider the modifications that this structure presents during the points prior to veraison. It is for this reason that in the present study different physiological, biochemical and molecular factors were analyzed. It was suggested that the different components of the cell wall are associated to the firmness of the fruit and must be analyzed as a whole due to the great phenotypic and molecular variations that the table grape presents during all its development, mainly in its early stages. Our results suggest that the decrease of texture in the berries is directly associated with the increase of the available epitope, corresponding to the ramifications of rhamnogalacturonan I and to the XXXG configuration in the chains of hemicellulose in the cell wall, observed by means of an immunohistochemical analysis. Enzymatic studies in the whole fruit show a high activity of the enzymes (3-Galactosidase and polygalacturonase in charge of wall remodeling, mainly in the early stages of development; observing a correlation between this activity and the expression of the genes corresponding to these enzymes during the first weeks post-anthesis of the fruit. In addition, there is an increase in the soluble elements of the wall correlated with a decrease in the firmness of the fruit after veraison. Therefore, our results suggest that the softening is due to the degradation of the different components of the cell wall, where the increase of pectins and hemicellulose in the first phases of wall fractionation presents the highest correlation with the firmness parameter.
Notas
Tesis (MagĆster en BiotecnologĆa)
Esta tesis se realizĆ³ en el Laboratorio de Postcosecha de la Facultad de Ciencias BiolĆ³gicas de la Universidad AndrĆ©s Bello y fue financiada por el proyecto FONDECYT NĀ°1150492 "Discovery of biomarker candidates linked to table grape berry firmness based on transcriptomic and metabolomic analyses".
Esta tesis se realizĆ³ en el Laboratorio de Postcosecha de la Facultad de Ciencias BiolĆ³gicas de la Universidad AndrĆ©s Bello y fue financiada por el proyecto FONDECYT NĀ°1150492 "Discovery of biomarker candidates linked to table grape berry firmness based on transcriptomic and metabolomic analyses".
Palabras clave
Uva de Mesa, Calidad, GenƩtica