The cytoskeleton is an early attribute of cellular life and its main components are composed of conserved proteins (Fletcher and Mullins, 2010). The actin cytoskeleton has a direct impact on cell size control in animal cells (Fletcher and Mullins, 2010; Faix et al., 1996), but its mechanistic contribution to cellular growth in plants remains largely elusive. Here, we reveal a role of actin in cell size regulation in plants. The actin cytoskeleton shows proximity to vacuoles, and the phytohormone auxin not only controls the organisation of actin filaments, but also impacts on vacuolar morphogenesis in an actin-dependent manner. Pharmacological and genetic interference with the actin-myosin system abolishes the auxin effect on vacuoles and thus disrupts its negative influence on cellular growth. SEM-based 3D nanometre resolution imaging of the vacuoles revealed that auxin controls the constriction and luminal size of the vacuole. We show that this actin-dependent mechanism controls the relative cellular occupancy of the vacuole, thus proposing an unanticipated mechanism for cytosol homeostasis during cellular growth.
Scheuring, DLofke, CKruger, FKittelman, M Eisa, AHughes, LSmith, RHawes, C Schumacher, KKleine-Vehn, J
Faculty of Health and Life Sciences\Department of Biological and Medical Sciences
Year of publication: 2015Date of RADAR deposit: 2016-02-09
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