The Specification of Geometric Edges by a Plant Rab GTPase Is an Essential Cell-Patterning Principle During Organogenesis in Arabidopsis

Abstract

SummaryPlant organogenesis requires control over division planes and anisotropic cell wall growth, which each require spatial patterning of cells. Polyhedral plant cells can display complex patterning in which individual faces are established as biochemically distinct domains by endomembrane trafficking. We now show that, during organogenesis, the Arabidopsis endomembrane system specifies an important additional cellular spatial domain: the geometric edges. Previously unidentified membrane vesicles lying immediately beneath the plasma membrane at cell edges were revealed through localization of RAB-A5c, a plant GTPase of the Rab family of membrane-trafficking regulators. Specific inhibition of RAB-A5c activity grossly perturbed cell geometry in developing lateral organs by interfering independently with growth anisotropy and cytokinesis without disrupting default membrane trafficking. The initial loss of normal cell geometry can be explained by a failure to maintain wall stiffness specifically at geometric edges. RAB-A5c thus meets a requirement to specify this cellular spatial domain during organogenesis.

Universal Methods for Transgene Induction Using the Dexamethasone‐Inducible Transcription Activation System pOp6/LhGR in Arabidopsis and Other Plant Species

“…These systems are especially required for expression of gene products that interfere with regeneration, growth, or reproduction; for expression at different stages of plant development and for a specific duration; for conditional genetic complementation; and for co‐suppression or overexpression studies. Temporal control can be particularly useful to de‐convolve complex phenotypes related to transgene expression, as it allows monitoring of the progressive development of phenotype and may thus reveal primary effects before homeostatic mechanisms start to counteract them (e.g., Kirchhelle et al., ). Furthermore, use of an appropriate promoter can restrict target transgene expression to specific organs, tissues, or even cell types.…”

Root Cell-Specific Regulators of Phosphate-Dependent Growth

“…Interestingly, key hub genes (kME . 0.9) are associated with Ca 2+ -dependent processes in vesicle trafficking and the ER stress response, such as the ADPribosylation factor encoding ARFB1A and ARFA1F (Memon, 2004), the Rab GTPase RAB-5ac/ARA4 (Kirchhelle et al, 2016), and genes encoding chaperones and foldases such as the protein disulfide isomerases PDI5 and PDI11, chaperone HSP90.7, and calreticulins CRT1a and CRT1b (Gupta and Tuteja, 2011). These ERrelated processes might be linked to the trafficking of PHTs through this cellular compartment (González et al, 2005), although PHF1 expression does not differ across mutants.…”

ENDOSOMAL RAB EFFECTOR WITH PX-DOMAIN, an Interacting Partner of RAB5 GTPases, Regulates Membrane Trafficking to Protein Storage Vacuoles in Arabidopsis

“…The unique organization of endosomal trafficking in plants is also demonstrated by the observation that the trans-Golgi network (TGN) acts as an early endosome in plants (Dettmer et al, 2006;Lam et al, 2007;Viotti et al, 2010), from which multivesicular endosomes are proposed to be directly generated by maturation (Niemes et al, 2010;Scheuring et al, 2011). The RAB11 group (also known as RABA in Arabidopsis), which is localized to TGNrelated secretory compartments and is involved in cell plate formation and tip growth (Preuss et al, 2004;Chow et al, 2008;Szumlanski and Nielsen, 2009;Kang et al, 2011;Feraru et al, 2012;Asaoka et al, 2013;Berson et al, 2014;Kirchhelle et al, 2016), is also implicated in endosomal/vacuolar trafficking (Bottanelli et al, 2011;Choi et al, 2013). These lines of evidence indicate that endosomal trafficking in plant cells operates in a different manner from that in non-plant organisms.…”