title: Pavement cells: a model system for non-transcriptional auxin signalling and crosstalks.
abstract: Auxin (indole acetic acid) is a multifunctional phytohormone controlling various developmental patterns, morphogenetic processes, and growth behaviours in plants. The transcription-based pathway activated by the nuclear TRANSPORT INHIBITOR RESISTANT 1/auxin-related F-box auxin receptors is well established, but the long-sought molecular mechanisms of non-transcriptional auxin signalling remained enigmatic until very recently. Along with the establishment of the Arabidopsis leaf epidermal pavement cell (PC) as an exciting and amenable model system in the past decade, we began to gain insight into non-transcriptional auxin signalling. The puzzle-piece shape of PCs forms from intercalated or interdigitated cell growth, requiring local intra- and inter-cellular coordination of lobe and indent formation. Precise coordination of this interdigitated pattern requires auxin and an extracellular auxin sensing system that activates plasma membrane-associated Rho GTPases from plants and subsequent downstream events regulating cytoskeletal reorganization and PIN polarization. Apart from auxin, mechanical stress and cytokinin have been shown to affect PC interdigitation, possibly by interacting with auxin signals. This review focuses upon signalling mechanisms for cell polarity formation in PCs, with an emphasis on non-transcriptional auxin signalling in polarized cell expansion and pattern formation and how different auxin pathways interplay with each other and with other signals.
authors.affiliation: Horticultural Plant Biology and Metabolomics Center, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
authors.forename: Jisheng
authors.initials: J
authors.lastname: Chen
authors.affiliation: Center for Plant Cell Biology, Department of Botany and Plant Sciences, University of California, Riverside, CA 92521, USA.
authors.forename: Fei
authors.initials: F
authors.lastname: Wang
authors.affiliation: Horticultural Plant Biology and Metabolomics Center, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
authors.forename: Shiqin
authors.initials: S
authors.lastname: Zheng
authors.affiliation: Center for Plant Stress Biology, Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 201602, China.
authors.forename: Tongda
authors.initials: T
authors.lastname: Xu
authors.affiliation: Center for Plant Cell Biology, Department of Botany and Plant Sciences, University of California, Riverside, CA 92521, USA zhenbiao.yang@ucr.edu.
authors.forename: Zhenbiao
authors.initials: Z
authors.lastname: Yang
mesh_terms: D016764:Cell Polarity; D007210:Indoleacetic Acids / Q000378:metabolism*; D063245:Plant Development; D019441:Plant Epidermis / Q000166:cytology / Q000378:metabolism*; D010937:Plant Growth Regulators / Q000378:metabolism*; D015398:Signal Transduction
chemical_list: D007210:Indoleacetic Acids; D010937:Plant Growth Regulators
keywords: ABP1; ROP GTPase; TIR1/AFB auxin receptor.; auxin; cytokinin; pavement cell