title: Trans-acting siRNA-mediated repression of ETTIN and ARF4 regulates heteroblasty in Arabidopsis.
abstract: Mutations in the ARGONAUTE gene ZIPPY(ZIP)/AGO7 in Arabidopsis accelerate the juvenile-to-adult transition. A screen for mutations that suppress this precocious phenotype yielded alleles of two auxin-related transcription factors known to be upregulated in zip: ETTIN (ETT)/ARF3 and ARF4. Mutations in ETT/ARF3 and ARF4 delay the expression of adult traits, demonstrating that these genes have non-redundant roles in shoot maturation. ZIP is not generally required for the production of trans-acting (ta) siRNAs, but is required for the production and/or stability of tasiR-ARF, a ta-siRNA that targets both ETT/ARF3 and ARF4. tasiR-ARF is absent in zip-2, and overexpression of a tasiR-ARF-insensitive form of ETT mimics the zip phenotype. We conclude that the precocious phenotype of zip is attributable to the absence of tasiR-ARF-mediated repression of ETT and ARF4. The abundance of tasiR-ARF, ETT/ARF3 and ARF4 RNA does not change during vegetative development. This result suggests that tasiR-ARF regulation establishes the threshold at which leaves respond to a temporal signal, rather than being a component of this signal.
authors.affiliation: Department of Biology, University of Pennsylvania, Philadelphia, PA 19104-6018, USA.
authors.forename: Christine
authors.initials: C
authors.lastname: Hunter
authors.forename: Matthew R
authors.initials: MR
authors.lastname: Willmann
authors.forename: Gang
authors.initials: G
authors.lastname: Wu
authors.forename: Manabu
authors.initials: M
authors.lastname: Yoshikawa
authors.forename: María
authors.initials: M
authors.lastname: de la Luz Gutiérrez-Nava
authors.forename: Scott R
authors.initials: SR
authors.lastname: Poethig
mesh_terms: D017360:Arabidopsis / Q000235:genetics*; D029681:Arabidopsis Proteins / Q000235:genetics*; D001483:Base Sequence; D004268:DNA-Binding Proteins / Q000235:genetics*; D035264:Flowers / Q000235:genetics; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics*; D010641:Phenotype; D018515:Plant Leaves / Q000235:genetics; D018749:RNA, Plant / Q000235:genetics; D034741:RNA, Small Interfering / Q000235:genetics*; D012098:Reproduction; D014157:Transcription Factors / Q000235:genetics*
chemical_list: C511457:ARF4 protein, Arabidopsis; D029681:Arabidopsis Proteins; D004268:DNA-Binding Proteins; C109765:ETT protein, Arabidopsis; D009687:Nuclear Proteins; D018749:RNA, Plant; D034741:RNA, Small Interfering; D014157:Transcription Factors