Structural alteration of plant cell wall in transgenic Arabidopsis thaliana

BUSI, M. V.; PERALTA, DA; GRISOLIA, M.; VALDEZ, H.; DIEGO FABIAN GOMEZ CASATI

}puerto Madryn

Congreso; XLVI Reunion SAIB; 2010

Carbohydrate-binding modules (CBM) are non-catalytic domains, clasified in 59 families, which are found being part of non-catalytic proteins, transport proteins and enzymes involved in polysaccharide metabolism (i.e. the dynamic plant cell wall metabolism). The SBD123 (Starch Binding Domain) from the N-term region of starch synthase III from A. thaliana was classified into the CBM53 family and this was the first CBM described in a biosynthetic enzyme. In vitro adsorption assays show that SBD123 has a promiscuous binding to starch and to other plant cell wall polysaccharides such as xylane, pectin and cellulose.  Considering the evolutionary advantage of SBDs to posses two binding sites in regard to the rest of the CBMs, we decided to evaluate this behavior in vivo. Thus, we carried out the expression of de SBD123 protein targeted to the plant cell wall by the transformation of A. thaliana plants with a chimeric construct of the signal peptide of Expansin 8 from A. thaliana fused to SBD123. Transgenic plants phenotype was evaluated by transcriptomic, metabolomic and fluorescence confocal microscopy. We found a decrease of  cell wall polysaccharide content with alterations in cell wall integrity, decrease of xylose and galactose (hemicellulose compounds) and increased mRNA levels for CESA 4, 7, 8 (involved in secondary cell wall synthesis) compared to wild type plants.