title: miR393 and secondary siRNAs regulate expression of the TIR1/AFB2 auxin receptor clade and auxin-related development of Arabidopsis leaves.
abstract: The phytohormone auxin is a key regulator of plant growth and development that exerts its functions through F-box receptors. Arabidopsis (Arabidopsis thaliana) has four partially redundant of these receptors that comprise the TRANSPORT INHIBITOR RESPONSE1/AUXIN SIGNALING F-BOX1 auxin receptor (TAAR) clade. Recent studies have shown that the microRNA miR393 regulates the expression of different sets of TAAR genes following pathogen infection or nitrate treatment. Here we report that miR393 helps regulate auxin-related development of leaves. We found that AtMIR393B is the predominant source for miR393 in all aerial organs and that miR393 down-regulates all four TAAR genes by guiding the cleavage of their mRNAs. A mutant unable to produce miR393 shows developmental abnormalities of leaves and cotyledons reminiscent of enhanced auxin perception by TAARs. Interestingly, miR393 initiates the biogenesis of secondary siRNAs from the transcripts of at least two of the four TAAR genes. Our results indicate that these siRNAs, which we call siTAARs, help regulate the expression of TAAR genes as well as several unrelated genes by guiding the cleavage of their mRNAs. Thus, miR393 and possibly siTAARs regulate auxin perception and certain auxin-related aspects of leaf development.
authors.affiliation: Friedrich Miescher Institute for Biomedical Research, Novartis Research Foundation, 4058 Basel, Switzerland.
authors.forename: Azeddine
authors.initials: A
authors.lastname: Si-Ammour
authors.forename: David
authors.initials: D
authors.lastname: Windels
authors.forename: Estelle
authors.initials: E
authors.lastname: Arn-Bouldoires
authors.forename: Claudia
authors.initials: C
authors.lastname: Kutter
authors.forename: Jérôme
authors.initials: J
authors.lastname: Ailhas
authors.forename: Frederick
authors.initials: F
authors.lastname: Meins
authors.forename: Franck
authors.initials: F
authors.lastname: Vazquez
mesh_terms: D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D018548:Cotyledon / Q000235:genetics / Q000254:growth & development; D015536:Down-Regulation; D044783:F-Box Proteins / Q000235:genetics* / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D007210:Indoleacetic Acids / Q000378:metabolism; D035683:MicroRNAs; D009154:Mutation; D035261:Plant Components, Aerial / Q000235:genetics / Q000378:metabolism; D018515:Plant Leaves / Q000235:genetics* / Q000254:growth & development*; D034741:RNA, Small Interfering; D011956:Receptors, Cell Surface / Q000235:genetics* / Q000378:metabolism
chemical_list: C559638:AFB4 protein, Arabidopsis; D029681:Arabidopsis Proteins; D044783:F-Box Proteins; D007210:Indoleacetic Acids; C559857:MIRN393 microRNA, Arabidopsis; D035683:MicroRNAs; D034741:RNA, Small Interfering; D011956:Receptors, Cell Surface; C501405:TIR1 protein, Arabidopsis