title: Auxin response cell-autonomously controls ground tissue initiation in the earlyArabidopsisembryo.
abstract: Plant organs are typically organized into three main tissue layers. The middle ground tissue layer comprises the majority of the plant body and serves a wide range of functions, including photosynthesis, selective nutrient uptake and storage, and gravity sensing. Ground tissue patterning and maintenance inArabidopsisare controlled by a well-established gene network revolving around the key regulatorSHORT-ROOT(SHR). In contrast, it is completely unknown how ground tissue identity is first specified from totipotent precursor cells in the embryo. The plant signaling molecule auxin, acting through AUXIN RESPONSE FACTOR (ARF) transcription factors, is critical for embryo patterning. The auxin effector ARF5/MONOPTEROS (MP) acts both cell-autonomously and noncell-autonomously to control embryonic vascular tissue formation and root initiation, respectively. Here we show that auxin response and ARF activity cell-autonomously control the asymmetric division of the first ground tissue cells. By identifying embryonic target genes, we show that MP transcriptionally initiates the ground tissue lineage and acts upstream of the regulatory network that controls ground tissue patterning and maintenance. Strikingly, whereas the SHR network depends on MP, this MP function is, at least in part, SHR independent. Our study therefore identifies auxin response as a regulator of ground tissue specification in the embryonic root, and reveals that ground tissue initiation and maintenance use different regulators and mechanisms. Moreover, our data provide a framework for the simultaneous formation of multiple cell types by the same transcriptional regulator.
authors.affiliation: Laboratory of Biochemistry, Wageningen University, Stippeneng 4, 6708 WE Wageningen, The Netherlands.
authors.forename: Barbara K
authors.initials: BK
authors.lastname: Möller
authors.affiliation: Laboratory of Biochemistry, Wageningen University, Stippeneng 4, 6708 WE Wageningen, The Netherlands.
authors.forename: Colette A
authors.initials: CA
authors.lastname: Ten Hove
authors.affiliation: National Research Council, Saskatoon, SK S7N 0W9, Canada.
authors.forename: Daoquan
authors.initials: D
authors.lastname: Xiang
authors.affiliation: Laboratory of Biochemistry, Wageningen University, Stippeneng 4, 6708 WE Wageningen, The Netherlands.
authors.forename: Nerys
authors.initials: N
authors.lastname: Williams
authors.affiliation: Laboratory of Biochemistry, Wageningen University, Stippeneng 4, 6708 WE Wageningen, The Netherlands.
authors.forename: Lorena González
authors.initials: LG
authors.lastname: López
authors.affiliation: Laboratory of Biochemistry, Wageningen University, Stippeneng 4, 6708 WE Wageningen, The Netherlands.
authors.forename: Saiko
authors.initials: S
authors.lastname: Yoshida
authors.affiliation: Laboratory of Biochemistry, Wageningen University, Stippeneng 4, 6708 WE Wageningen, The Netherlands.
authors.forename: Margot
authors.initials: M
authors.lastname: Smit
authors.affiliation: National Research Council, Saskatoon, SK S7N 0W9, Canada.
authors.forename: Raju
authors.initials: R
authors.lastname: Datla
authors.affiliation: Laboratory of Biochemistry, Wageningen University, Stippeneng 4, 6708 WE Wageningen, The Netherlands; dolf.weijers@wur.nl.
authors.forename: Dolf
authors.initials: D
authors.lastname: Weijers
mesh_terms: D017360:Arabidopsis / Q000196:embryology* / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D019521:Body Patterning; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D007210:Indoleacetic Acids / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D004268:DNA-Binding Proteins; D007210:Indoleacetic Acids; C111371:MONOPTEROS protein, Arabidopsis; C410510:SHORT ROOT protein, Arabidopsis; D014157:Transcription Factors
keywords: auxin; embryogenesis; ground tissue; pattern formation; plant development