Hosted by: Dominique Bergmann
Development often relies on extrinsic (non-cell-autonomous) signals as positional cues and determinants of cell fate. During plant development, intercellular communication serves a critical role in the coordination of asymmetric cell divisions and differential cell fate specification that are essential to establish and maintain tissue patterning. While the polar localization of factors involved in root-shoot patterning has received considerable attention, how polarity is involved in tissue patterning in the radial axis remains largely unexplored. Using high-resolution spatial and temporal gene expression data, an in silico screen was conducted for genes predicted to function in radial tissue patterning. One of the genes we identified, POLARLY LOCALIZED KINASE 1 (PLK1), encodes a transmembrane receptor-like kinase (RLK) that is polarly localized to lateral domains in embryonic and root tissues. Unexpectedly, PLK1 polarity varies with cell type and is maintained under a variety of conditions that disrupt the localization of other transmembrane proteins. plk1 mutants exhibit altered cell morphology that appears to arise from abnormal positioning of cell division planes. We propose that directional, extrinsic cues are perceived by laterally polar RLK-mediated signaling domains and that these domains are established by a distinct paradigm in cell polarity.