Cell wall disintegration alters starch and sucrose metabolism

GRISOLÍA, M; PERALTA, DA; DIEGO FABIAN GOMEZ CASATI; BUSI, M. V.

Potrero de los Funes

Congreso; XLVII Reunion SAIB; 2011

SAIB

CBM (carbohydratebindingmodules)are structures associated to catalytic domains which have the ability tobind to different polysaccharides. Among these,those with a strong affinity for starch (SBD) have an evolutionary advantage due to thepresence of two substrate binding sites. We have fused the SSIII (AT1G11720) SBD to the signal peptide of EXPA8 (AT2G40610), and targeted to the cell wall of Arabidopsis plants. Transgenic plants showed an altered cell wall structure and composition. Interestingly, we observed an increase of transient starch levels from leaves collected at the end of the day.In addition, we found a modified amylose:amylopectinratio.  We also performed transcriptomicstudies in order to analyze the expression of several genes that encode enzymes involved in starch and sucrose metabolism. We found evidence suggesting that the increase in starch content in the transgenic plants could be explained by a decrease inits degradation; while the alteration in the compositionof this polysaccharide could be due to changes in the catalytic activity of other enzymes involved in the biosynthetic pathway. Finally, we have been detected a decrease in the levels of transcripts coding for key enzymes involved in the degradation of sucrose and therefore associated with decreased production of UDPGlc and fructose, two precursors of cell wall polysaccharides