Critical role of actin bundling in plant cell morphogenesis.

Actin microfilaments form highly-organized structures, such as arrays, meshwork and bundles, and are involved in cell division, organelle motility and intracellular transport in plants. Such organization is indicative of their vital role in directing plant cell morphogenesis. However, the physiological impact of changes in actin bundling level has been unclear until recently, despite progress in our understanding of their roles following actin microfilament disruption. Recent advances have shown that actin bundling levels can be modified through expression of actin binding proteins, or by using auxin transport inhibitors or auxin itself. The technical aspects of these findings have underscored the importance of actin bundling levels in plant cell morphogenesis, including cell division, cell elongation/expansion and stomatal movements. Based on such progress, we discuss the possible mechanisms that connect the actin microfilaments status with cellular dynamics.