title: Regulation of preprocambial cell state acquisition by auxin signaling in Arabidopsis leaves.
abstract: The principles underlying the formation of veins in the leaf have long intrigued developmental biologists. In Arabidopsis leaves, files of anatomically inconspicuous subepidermal cells that will elongate into vein-forming procambial cells selectively activate ATHB8 gene expression. The biological role of ATHB8 in vein formation and the molecular events that culminate in acquisition of the ATHB8 preprocambial cell state are unknown, but intertwined pathways of auxin transport and signal transduction have been implicated in defining paths of vascular strand differentiation. Here we show that ATHB8 is required to stabilize preprocambial cell specification against auxin transport perturbations, to restrict preprocambial cell state acquisition to narrow fields and to coordinate procambium formation within and between veins. We further show that ATHB8 expression at preprocambial stages is directly and positively controlled by the auxin-response transcription factor MONOPTEROS (MP) through an auxin-response element in the ATHB8 promoter. We finally show that the consequences of loss of ATHB8 function for vein formation are masked by MP activity. Our observations define, at the molecular level, patterning inputs of auxin signaling in vein formation.
authors.affiliation: Department of Biological Sciences, University of Alberta, CW-405 Biological Sciences Building, Edmonton AB, T6G 2E9, Canada.
authors.forename: Tyler J
authors.initials: TJ
authors.lastname: Donner
authors.forename: Ira
authors.initials: I
authors.lastname: Sherr
authors.forename: Enrico
authors.initials: E
authors.lastname: Scarpella
mesh_terms: D017360:Arabidopsis / Q000166:cytology / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D001693:Biological Transport, Active; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism; D007210:Indoleacetic Acids / Q000378:metabolism*; D016350:Leucine Zippers / Q000235:genetics; D009154:Mutation; D018515:Plant Leaves / Q000166:cytology / Q000254:growth & development / Q000378:metabolism; D030821:Plants, Genetically Modified; D011401:Promoter Regions, Genetic; D017384:Sequence Deletion; D015398:Signal Transduction
chemical_list: D029681:Arabidopsis Proteins; D018398:Homeodomain Proteins; D007210:Indoleacetic Acids