A role for pectin de-methylesterification in a developmentally regulated growth acceleration in dark-grown Arabidopsis hypocotyls
Résumé
We focused on a developmentally regulated growth acceleration in the darkgrown Arabidopsis hypocotyl to study the role of changes in cell wall metabolism in the control of cell elongation. To this end, precise transcriptome analysis on dissected dark-grown hypocotyls, ourier transform infrared (FT-IR) microspectroscopy and kinematic analysis were used. Using a cellulose synthesis inhibitor, we showed that the growth acceleration marks a developmental transition during which growth becomes uncoupled from cellulose synthesis. We next investigated the cellular changes that take place during this transition. FT-IR microspectroscopy revealed significant changes in cell wall composition during, but not after, the growth acceleration. Transcriptome analysis suggested a role for cell wall remodeling, in particular pectin modification, in this growth acceleration. This was confirmed by the overexpression of a pectin methylesterase inhibitor, which caused a delay in the growth acceleration. This study shows that the acceleration of cell elongation marks a developmental transition in dark-grown hypocotyl cells and supports a role for pectin demethylesterification in the timing of this event.
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