A Plausible Microtubule-Based Mechanism for Cell Division Orientation in Plant Embryogenesis

Oriented cell divisions are significant in plant morphogenesis because plant cells are embedded in cell walls and cannot relocate. Cell divisions follow various regular orientations, but the underlying mechanisms have not been clarified. We show that cell-shape dependent self organisation of cortical microtubule arrays is crucial for determining planes of early tissue-
generating divisions and forms the basis forrobust control of cell division orientation
in the embryo. To achieve this, we simulate microtubules on actual cell surface shapes from which we derive a minimal set of three rules for proper array
orientation. The first rule captures the effects of cell shape alone on microtubule organisation
, the second rule describes the regulation of microtubule stability at cell edges
and the third rule includes the differential effect of auxin on local microtubule stability. These rules explain early embryonic division plane orientations
and offer a framework for understanding patterned cell divisions in plant
morphogenesis.