title: The exoribonuclease XRN4 is a component of the ethylene response pathway in Arabidopsis.
abstract: EXORIBONUCLEASE4 (XRN4), the Arabidopsis thaliana homolog of yeast XRN1, is involved in the degradation of several unstable mRNAs. Although a role for XRN4 in RNA silencing of certain transgenes has been reported, xrn4 mutant plants were found to lack any apparent visible phenotype. Here, we show that XRN4 is allelic to the unidentified components of the ethylene response pathway ETHYLENE-INSENSITIVE5/ACC-INSENSITIVE1 (EIN5/AIN1) and EIN7. xrn4 mutant seedlings are ethylene-insensitive as a consequence of the upregulation of EIN3 BINDING F-BOX PROTEIN1 (EBF1) and EBF2 mRNA levels, which encode related F-box proteins involved in the turnover of EIN3 protein, a crucial transcriptional regulator of the ethylene response pathway. Epistasis analysis placed XRN4/EIN5/AIN1 downstream of CTR1 and upstream of EBF1/2. XRN4 does not appear to regulate ethylene signaling via an RNA-INDUCED SILENCING COMPLEX-based RNA silencing mechanism but acts by independent means. The identification of XRN4 as an integral new component in ethylene signaling adds RNA degradation as another posttranscriptional process that modulates the perception of this plant hormone.
authors.affiliation: Institut de Biologie Moléculaire des Plantes, Laboratoire Propre du Centre National de la Recherche Scientifique, Unité Propre de Recherche 2357, Conventioné avec l'Université Louis Pasteur, 67084 Strasbourg, France.
authors.forename: Thomas
authors.initials: T
authors.lastname: Potuschak
authors.forename: Amérin
authors.initials: A
authors.lastname: Vansiri
authors.forename: Brad M
authors.initials: BM
authors.lastname: Binder
authors.forename: Esther
authors.initials: E
authors.lastname: Lechner
authors.forename: Richard D
authors.initials: RD
authors.lastname: Vierstra
authors.forename: Pascal
authors.initials: P
authors.lastname: Genschik
mesh_terms: D000483:Alleles; D017360:Arabidopsis / Q000187:drug effects / Q000201:enzymology* / Q000254:growth & development; D029681:Arabidopsis Proteins / Q000378:metabolism; D005030:Ethylenes / Q000378:metabolism* / Q000494:pharmacology; D005095:Exoribonucleases / Q000235:genetics / Q000378:metabolism*; D044783:F-Box Proteins / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D018546:Hypocotyl / Q000187:drug effects / Q000201:enzymology / Q000254:growth & development; D007700:Kinetics; D035683:MicroRNAs / Q000378:metabolism; D008954:Models, Biological; D009154:Mutation / Q000235:genetics; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism; D015854:Up-Regulation / Q000187:drug effects
chemical_list: D029681:Arabidopsis Proteins; C481044:EBF1 protein, Arabidopsis; C481045:EBF2 protein, Arabidopsis; C494589:EIL1 protein, Arabidopsis; D005030:Ethylenes; D044783:F-Box Proteins; D035683:MicroRNAs; D010940:Plant Proteins; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D014157:Transcription Factors; C418137:Xrn1 protein, plant; C036216:ethylene; D005095:Exoribonucleases