Search for: All records

Abstract Cell polarity is a fundamental feature underlying cell morphogenesis and organismal development. In theArabidopsisstomatal lineage, the polarity protein BASL controls stomatal asymmetric cell division. However, the cellular machinery by which this intrinsic polarity site is established remains unknown. Here, we identify the PRAF/RLD proteins as BASL physical partners and mutating fourPRAFmembers leads to defects in BASL polarization. Members of PRAF proteins are polarized in stomatal lineage cells in a BASL-dependent manner. Developmental defects of theprafmutants phenocopy those of thegnommutants. GNOM is an activator of the conserved Arf GTPases and plays important roles in membrane trafficking. We further find PRAF physically interacts with GNOM in vitro and in vivo. Thus, we propose that the positive feedback of BASL and PRAF at the plasma membrane and the connected function of PRAF and GNOM in endosomal trafficking establish intrinsic cell polarity in theArabidopsisstomatal lineage. 

Summary Quantitative information on the spatiotemporal distribution of polarised proteins is central for understanding cell‐fate determination, yet collecting sufficient data for statistical analysis is difficult to accomplish with manual measurements.Here we present Polarity Measurement (Pome), a semi‐automated pipeline for the quantification of cell polarity and demonstrate its application to a variety of developmental contexts.Pomeanalysis reveals that, during asymmetric cell divisions in theArabidopsis thalianastomatal lineage, polarity proteins BASL and BRXL2 are more asynchronous and less mutually dependent than previously thought. A similar analysis of the linearly arrayed stomatal lineage ofBrachypodium distachyonrevealed that the MAPKKK BdYDA1 is segregated and polarised following asymmetrical divisions.Our results demonstrate that Pomeis a versatile tool, which by itself or combined with tissue‐level studies and advanced microscopy techniques can help to uncover new mechanisms of cell polarity. 

With growing populations and pressing environmental problems, future economies will be increasingly plant-based. Now is the time to reimagine plant science as a critical component of fundamental science, agriculture, environmental stewardship, energy, technology and healthcare. This effort requires a conceptual and technological framework to identify and map all cell types, and to comprehensively annotate the localization and organization of molecules at cellular and tissue levels. This framework, called the Plant Cell Atlas (PCA), will be critical for understanding and engineering plant development, physiology and environmental responses. A workshop was convened to discuss the purpose and utility of such an initiative, resulting in a roadmap that acknowledges the current knowledge gaps and technical challenges, and underscores how the PCA initiative can help to overcome them.