Cell Polarity Signaling in Arabidopsis

Abstract

Cell polarization is intimately linked to plant development, growth, and responses to the environment. Major advances have been made in our understanding of the signaling pathways and networks that regulate cell polarity in plants owing to recent studies on several model systems, e.g., tip growth in pollen tubes, cell morphogenesis in the leaf epidermis, and polar localization of PINs. From these studies we have learned that plant cells use conserved mechanisms such as Rho family GTPases to integrate both plant-specific and conserved polarity cues and to coordinate the cytoskeketon dynamics/reorganization and vesicular trafficking required for polarity establishment and maintenance. This review focuses upon signaling mechanisms for cell polarity formation in Arabidopsis, with an emphasis on Rho GTPase signaling in polarized cell growth and how these mechanisms compare with those for cell polarity signaling in yeast and animal systems.

Rho of Plant GTPase Signaling Regulates the Behavior of Arabidopsis Kinesin-13A to Establish Secondary Cell Wall Patterns

“…Cortical microtubules are sparse in the lobes of leaf epidermal cells (Fu et al, 2005) and are absent in the apex of growing pollen tubes (Yang, 2008) and root hairs (Van Bruaene et al, 2004). At the pollen tube apex, ROP GTPases are activated, and ROP INTERACTIVE PARTNER1 (RIP1)/INTERACTOR OF CONSTITUTIVE ACTIVE ROPS1 (ICR1), which belongs to the same family as MIDD1, is also localized (Li et al, 2008).…”

Patterning of plant cell wall deposition by cortical microtubules

“…To answer this question, the upstream proteins that control the activity of MIDD1/AtKinesin13A based microtubule depletion needs to be taken into account. GTPases are suitable candidates known to be involved in plant cell polarity regulation and their ability to interact with the cytoskeleton 121 . Local self-sustaining feedback loops between GTPases and the cytoskeleton regulate cell polarity and determine vesicular trafficking enabling cell morphogenesis 121 .…”

“…GTPases are suitable candidates known to be involved in plant cell polarity regulation and their ability to interact with the cytoskeleton 121 . Local self-sustaining feedback loops between GTPases and the cytoskeleton regulate cell polarity and determine vesicular trafficking enabling cell morphogenesis 121 . This mechanism is elegantly demonstrated in the morphogenesis of pavement cells in plants with a jigsaw-puzzle like appearance.…”

Cytokinin signaling regulates pavement cell morphogenesis in Arabidopsis

“…Arabidopsis leaf pavement cells (PCs) form an interdigitated pattern with complementary lobes and indentations through the development of interdigitated multipolarity and subsequent local expansion at each polar site [25]. Thus, the generation of interdigitated lobes and indentations in the two-dimensional plane of the leaf epidermis provides a nice model system to investigate the planar coordination of cell polarity and morphogenesis among cells within a tissue [25][26][27][28][29][30][31].…”

“…Thus, the generation of interdigitated lobes and indentations in the two-dimensional plane of the leaf epidermis provides a nice model system to investigate the planar coordination of cell polarity and morphogenesis among cells within a tissue [25][26][27][28][29][30][31]. Our recent studies suggest that auxin locally coordinates lobe formation with indentation by activating two counteracting Rho GTPase-based signaling pathways: the lobe-promoting ROP2 pathway localized to the lobe-forming region, and the lobe-restricting (indentation-promoting) ROP6 pathway localized to the indenting region of the plasma membrane (PM) [28][29][30].…”