INSTITUTO DE FISIOLOGIA VEGETAL
Unidad Ejecutora - UE
congresos y reuniones científicas
Influence of the carbohydrate-binding module of strawberry Expansin-2 on Arabidopsis thaliana cell wall.
NARDI, C; VILLARREAL NM; MARTÍNEZ GA; CIVELLO, PM
Congreso; 47° Reunión Anual SAIB.; 2011
Expansins are proteins involved in plant cell wall modifications. Ithas been described three domains in expansins, a signal peptidewhich directs the protein to the secretory pathway, a central glycosylhydrolase domain, and a C-terminal domain considered as acarbohydrate-binding module (CBM). The CBM would beanchoring the expansin to the cellulose surface, and the centraldomain would interact with hemicelluloses. In the present study, wehave targeted the expression of the strawberry expansin2 CBM(CBM-FAEXP2) to A. thaliana cell walls, to test the hypothesis thatthe over-expression of a expansin CBM would bind cell wall sitesand then interfere with cell wall degrading enzymes. A. thalianaplants were transformed and three homozygous lines were selected.An increase in the total amount of cell wall was observed, mainlydue to an increase of pectin fraction, while cellulose andhemicelluloses fractions were not affected. Regarding the enzymeactivities, there was a significant decrease in polygalacturonase, ßgalactosidaseand xylosidase activities in transgenic lines. A tensileanalysis of the shoot showed that transgenic lines were moreextensible than wild type. Our results support the hypothesis thatCBM-FAEXP2 over-expression would block the action ofhydrolytic enzymes, leading to lower pectin degradation and thenproducing a more extensible cell wall.