The formation of the lobes at the Arabidopsis leaf margin are due to differences in local auxin accumulation, coordinated by auxin efflux carrier (PIN1) and transcriptional regulator (CUC2), but the molecular mechanisms acting upstream are not yet understood. Among viable leaf shape mutants, Wilson-Sanchez and colleagues identified that mutation of VASCULATURE COMPLEXITY AND CONNECTIVITY (VCC), also known as desigual1-1 (deal1-1), results in loss of bilateral symmetry, due to uncoordinated cell division at the leaf margins. The expression pattern of VCC coincides with basipetally regressing cell division. Spatial segregation between auxin maxima and CUC2 expression was disturbed in vcc mutants, suggesting that VCC is necessary for communication between growth promoting and repressing signals. Whether genes from the VCC family are guarding bilateral symmetry of other organs remains to be unveiled. (Summary by Magdalena Julkowska) New Phytol.
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