Cell axiality and polarity in plants--adding pieces to the puzzle

Plant cell polarity is important for cellular function and multicellular development. Classical physiological and cell biological analyses identified cues that orient cell polarity and suggested molecules that translate a cue into intracellular asymmetry. A range of proteins that either mark or are involved in the establishment of a (polar) axis are now available, as are many relevant mutants. These tools are likely to facilitate a dissection of the molecular mechanisms behind cell and organ polarity in the near future.