Caracterización funcional dela enzima de la pared celular xiloglucano endotransglucosilasa.
The main object of this Thesis doctoral work was based in the physiological, biochemical and molecular characterization of the xyloglucan endotransglucosilase / hidrolase enzime. To achieve this, we have worked with tomato plants (Solanum lycopersicum L.) as a model system of Money Maker and Canario variety and transgenics plants, which have over-expression and repression level of expression of SlXTH1.
On the one hand, our purpose was the study of the participation of XET in the plants growing, elongation and cellular expansion. After that, the second partial objective, was based on clarifying the implication of XET in fruits growing and softening. Moreover, it was to assess the paper of enzimes implicated in the cell wall metabolism of fruits during infection by fungus pathogen and in particulary, the implication of XET. Finally, we had studied the possible regulation of XTHs by ethylene.
The most relevant conclusions were the following items:
1. This is the first time that transgenics plants which have increased the levels of expression of XTH gene and show an increase in the enzimatic XET activity have been described.
2. In seedling, the sobre-expression of SlXTH1 gene, mainly increases the XET soluble activity, which implies irreversible and permanent changes in the links of xyloglucan with the rest of components, facts that were responsible of an increase of extensibility in epycotils. These results suggest that XET is implicated in growing.
3. In plants that have a decrease on the expression of SlXTH1 gene, changes in the fenotype it were found (plant slimmer and lighter), although these plants reached the same height. These results suggest that SlXTH1 gene would be implicated in vascular veins differentiation.
4. The fruits of plants that have sobre-expression SlXTH1 gene were harder and had higher molecular mass that wild fruits, due to changes in xyloglucan structure caused by XET activity. This suggests that XET is implicated in supporting the structure of cell wall.
5. The genetic expression of SlXTHs and activity XET decreased in fruits which suffer from biotic stress (fungus infection). In this case, we suggest the possibility of a fungus molecular regulation in SlXTHs genes.
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Advisor:Pérez Lorences, Ester
School:Universitat de València
Source Type:Master's Thesis
Date of Publication:07/20/2007