Quantification of Cell Division Angles in the Arabidopsis Root

In many plant tissues, division plane orientation within cell files is highly predictable since all cells divide almost perpendicular to the cell file axis. Many mutations can affect division plane orientation, and the quantification of the deviation from the expected transverse orientation in various genetic backgrounds is thus an important issue.While several software tools have been proposed for the quantification of cellular morphology in plant tissues, none of them allowed investigating division plane orientation. We propose here a complete method for measuring orientation of division planes in 2D, using an open-source ImageJ plugin named "Cell File Angles." The method comprises the staining of cell wall within whole mount roots with the calcofluor dye, the acquisition of 3D Z-stacks of the stained roots, and the measurement of cell wall orientation using image processing algorithms and semi-automated analysis.