The Actomyosin System in Plant Cell Division: Lessons Learned from Microscopy and Pharmacology

Abstract

Actin and myosin (i.e., the actomyosin system) play pivotal roles in plants, including organelle movement, cytoplasmic streaming, cell expansion, responses to microbes, cell signaling, and cell division. Among the plant biological processes attributed to actin and myosin function, understanding their precise role in cell division has been one of the more challenging problems to address. The difficulties in linking actomyosin function to cell division come in large part from inconsistent actin labeling in the cell division apparatus to the mild cell division phenotypes of actomyosin mutants. While the latter can be explained by functional redundancy, the presence of actin and myosin in the mitotic spindle has been somewhat controversial. Nonetheless, genetically encoded live actin and myosin probes have confirmed some classic microscopy results reported decades ago while also uncovering unique structures associated with the plant cell division machinery. In this chapter, we discuss how early microscopic work and recent live cell imaging data are beginning to provide a more unified view on how the actomyosin system facilitates cell division in plants.