Arabidopsis DEFECTIVE KERNEL1 regulates cell wall composition and axial growth in the inflorescence stem

Plants can reach impressive heights, thanks to the mechanical stability provided by the cell walls. The required strength is ensured by coordination of cell wall deposition and cell expansion. Plant-specific calpain (DEK1) regulates axial stem growth, as lines overexpressing the calpain domain develop shorter stems than wild-type plants, while the opposite was observed for amiRNA lines targeting DEK1. The change in stem thickness was related to the cell number, shape and size, mainly in the cortical, interfascicular fiber region and pith layer cells. The deposition of pectin, cellulose and secondary cell wall components was affected in the mutant lines. The authors propose that altered cell wall composition impacts coordination of growth within and between cell layers. Whether increased cell wall thickness is a consequence or the cause for reduced elongation remains to be investigated in the future studies. (Summary by Magdalena Julkowska) Plant Direct 10.1002/pld3.27