title: ARF7 and ARF19 regulate lateral root formation via direct activation of LBD/ASL genes in Arabidopsis.
abstract: Lateral root formation in Arabidopsis thaliana is regulated by two related AUXIN RESPONSE FACTORs, ARF7 and ARF19, which are transcriptional activators of early auxin response genes. The arf7 arf19 double knockout mutant is severely impaired in lateral root formation. Target-gene analysis in arf7 arf19 transgenic plants harboring inducible forms of ARF7 and ARF19 revealed that ARF7 and ARF19 directly regulate the auxin-mediated transcription of LATERAL ORGAN BOUNDARIES-DOMAIN16/ASYMMETRIC LEAVES2-LIKE18 (LBD16/ASL18) and/or LBD29/ASL16 in roots. Overexpression of LBD16/ASL18 and LBD29/ASL16 induces lateral root formation in the absence of ARF7 and ARF19. These LBD/ASL proteins are localized in the nucleus, and dominant repression of LBD16/ASL18 activity inhibits lateral root formation and auxin-mediated gene expression, strongly suggesting that these LBD/ASLs function downstream of ARF7- and ARF19-dependent auxin signaling in lateral root formation. Our results reveal that ARFs regulate lateral root formation via direct activation of LBD/ASLs in Arabidopsis.
authors.affiliation: Nara Institute of Science and Technology, Graduate School of Biological Sciences, Takayama 8916-5, Ikoma, Nara 630-0101, Japan.
authors.forename: Yoko
authors.initials: Y
authors.lastname: Okushima
authors.forename: Hidehiro
authors.initials: H
authors.lastname: Fukaki
authors.forename: Makoto
authors.initials: M
authors.lastname: Onoda
authors.forename: Athanasios
authors.initials: A
authors.lastname: Theologis
authors.forename: Masao
authors.initials: M
authors.lastname: Tasaka
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D018506:Gene Expression Regulation, Plant; D007210:Indoleacetic Acids / Q000378:metabolism; D005810:Multigene Family; D009154:Mutation; D010802:Phylogeny; D018517:Plant Roots / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D015398:Signal Transduction; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism / Q000502:physiology*
chemical_list: C503426:ARF19 protein, Arabidopsis; C503425:ARF7 protein, Arabidopsis; D029681:Arabidopsis Proteins; D007210:Indoleacetic Acids; C571893:LBD16 protein, Arabidopsis; D015534:Trans-Activators; D014157:Transcription Factors