title: Cytokinin signaling regulates pavement cell morphogenesis in Arabidopsis.
abstract: The puzzle piece-shaped Arabidopsis leaf pavement cells (PCs) with interdigitated lobes and indents is a good model system to investigate the mechanisms that coordinate cell polarity and shape formation within a tissue. Auxin has been shown to coordinate the interdigitation by activating ROP GTPase-dependent signaling pathways. To identify additional components or mechanisms, we screened for mutants with abnormal PC morphogenesis and found that cytokinin signaling regulates the PC interdigitation pattern. Reduction in cytokinin accumulation and defects in cytokinin signaling (such as in ARR7-over-expressing lines, the ahk3cre1 cytokinin receptor mutant, and the ahp12345 cytokinin signaling mutant) enhanced PC interdigitation, whereas over-production of cytokinin and over-activation of cytokinin signaling in an ARR20 over-expression line delayed or abolished PC interdigitation throughout the cotyledon. Genetic and biochemical analyses suggest that cytokinin signaling acts upstream of ROPs to suppress the formation of interdigitated pattern. Our results provide novel mechanistic understanding of the pathways controlling PC shape and uncover a new role for cytokinin signaling in cell morphogenesis.
authors.affiliation: Center for Plant Cell Biology, Department of Botany and Plant Sciences, University of California, Riverside, CA 92521, USA.
authors.forename: Hongjiang
authors.initials: H
authors.lastname: Li
authors.forename: Tongda
authors.initials: T
authors.lastname: Xu
authors.forename: Deshu
authors.initials: D
authors.lastname: Lin
authors.forename: Mingzhang
authors.initials: M
authors.lastname: Wen
authors.forename: Mingtang
authors.initials: M
authors.lastname: Xie
authors.forename: Jérôme
authors.initials: J
authors.lastname: Duclercq
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Bielach
authors.forename: Jungmook
authors.initials: J
authors.lastname: Kim
authors.forename: G Venugopala
authors.initials: GV
authors.lastname: Reddy
authors.forename: Jianru
authors.initials: J
authors.lastname: Zuo
authors.forename: Eva
authors.initials: E
authors.lastname: Benková
authors.forename: Jiří
authors.initials: J
authors.lastname: Friml
authors.forename: Hongwei
authors.initials: H
authors.lastname: Guo
authors.forename: Zhenbiao
authors.initials: Z
authors.lastname: Yang
mesh_terms: D017360:Arabidopsis / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D003583:Cytokinins / Q000235:genetics / Q000378:metabolism*; D019204:GTP-Binding Proteins / Q000378:metabolism; D007210:Indoleacetic Acids / Q000494:pharmacology; D009024:Morphogenesis / Q000187:drug effects; D018515:Plant Leaves / Q000166:cytology* / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000378:metabolism; D011494:Protein Kinases / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000378:metabolism; D015398:Signal Transduction; D014157:Transcription Factors / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D003583:Cytokinins; D007210:Indoleacetic Acids; D011956:Receptors, Cell Surface; D014157:Transcription Factors; D011494:Protein Kinases; C421783:WOL protein, Arabidopsis; D019204:GTP-Binding Proteins