| Abstract Detail
Conference Wide Ratzka, Antje [1], Usadel, Björn [1], Pauly, Markus [1]. Exploration of the nucleotide sugar conversion pathway in tomato fruits and its influence on the cell wall polysaccharides. HIGHER plant cells are encased in walls which contribute not only to their structural integrity but whose metabolism plays also a major role in growth, differentiation, transport, senescence and intercellular communication. The walls of tomato fruits consist mainly of pectins which are characterized by a high content of galacturonate and responsible for the texture. Changes in pectin structure occur during fruit ripening and result in softening, which is important for processing to juice and paste. Despite the detailed knowledge about the pectin structure, far less is known about its biosynthesis. Previous work indicated that one of the activated precursors necessary for the synthesis of pectins is UDP-D-galacturonate, which is synthesized from UDP-D glucuronate by a UDP-D-glucuronate 4-epimerase (GAE). A blast search using GAE sequences identified in the Arabidopsis thaliana genome indicated that Solanum lycopersicum contains at least four GAE family members (GAE 1-4). The expression pattern of the GAE isoforms in different plant organs and fruit ripening stages was verified by qRT-PCR. In an attempt to modify the galacturonic acid content of tomato fruits, an RNAi construct consisting of fragments of all four endogenous tomato GAE genes under the control of a fruit specific promoter was transformed into tomato plants to analyse the effect of silencing of this gene family on wall composition. As an alternative strategy one of the A. thaliana genes (GAE 6) was overexpressed in tomato plants facilitating the 35S promoter. Several overexpressing lines were identified via Northern blot. Fruits of different ripening stages as well as leaves were analysed for changes in wall composition. Additionally pectin specific antibody labelling of petiole and fruit pericarp sections revealed a tissue specific localisation. These experiments should not only yield tomato fruits with altered pectin content but also give insights about the function of pectin during fruit development and ripening.
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1 - MPI of Molecular Plant Physiology, Am Mühlenberg 1, Golm, 14476, germany
Keywords:
cell wall
nucleotide sugar conversion pathway
tomato fruit
pectin
UDP-D-glucuronate 4-epimerase.
Session: Poster-83
Location: Ballroom CD/Monona Terrace
Date: Tuesday, July 25th, 2006
Time: 8:00 AM
Abstract ID:65 |
