title: The MYB23 gene provides a positive feedback loop for cell fate specification in the Arabidopsis root epidermis.
abstract: The specification of cell fates during development requires precise regulatory mechanisms to ensure robust cell type patterns. Theoretical models of pattern formation suggest that a combination of negative and positive feedback mechanisms are necessary for efficient specification of distinct fates in a field of differentiating cells. Here, we examine the role of the R2R3-MYB transcription factor gene, AtMYB23 (MYB23), in the establishment of the root epidermal cell type pattern in Arabidopsis thaliana. MYB23 is closely related to, and is positively regulated by, the WEREWOLF (WER) MYB gene during root epidermis development. Furthermore, MYB23 is able to substitute for the function of WER and to induce its own expression when controlled by WER regulatory sequences. We also show that the MYB23 protein binds to its own promoter, suggesting a MYB23 positive feedback loop. The localization of MYB23 transcripts and MYB23-green fluorescent protein (GFP) fusion protein, as well as the effect of a chimeric MYB23-SRDX repressor construct, links MYB23 function to the developing non-hair cell type. Using mutational analyses, we find that MYB23 is necessary for precise establishment of the root epidermal pattern, particularly under conditions that compromise the cell specification process. These results suggest that MYB23 participates in a positive feedback loop to reinforce cell fate decisions and ensure robust establishment of the cell type pattern in the Arabidopsis root epidermis.
authors.affiliation: Department of Biology, Yonsei University, 134 Sinchon-dong, Seoul 120-749, Korea.
authors.forename: Yeon Hee
authors.initials: YH
authors.lastname: Kang
authors.forename: Victor
authors.initials: V
authors.lastname: Kirik
authors.forename: Martin
authors.initials: M
authors.lastname: Hulskamp
authors.forename: Kyoung Hee
authors.initials: KH
authors.lastname: Nam
authors.forename: Katherine
authors.initials: K
authors.lastname: Hagely
authors.forename: Myeong Min
authors.initials: MM
authors.lastname: Lee
authors.forename: John
authors.initials: J
authors.lastname: Schiefelbein
mesh_terms: D017360:Arabidopsis / Q000166:cytology / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D002454:Cell Differentiation; D002467:Cell Nucleus / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D025461:Feedback, Physiological; D018506:Gene Expression Regulation, Plant; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism; D018517:Plant Roots / Q000166:cytology / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic; D020598:Proto-Oncogene Proteins c-myb / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D014157:Transcription Factors / Q000032:analysis / Q000235:genetics / Q000378:metabolism / Q000502:physiology*
chemical_list: D029681:Arabidopsis Proteins; C511989:CPC protein, Arabidopsis; D004268:DNA-Binding Proteins; C089991:GL2 protein, Arabidopsis; D018398:Homeodomain Proteins; C543128:MYB23 protein, Arabidopsis; D020598:Proto-Oncogene Proteins c-myb; D012333:RNA, Messenger; D014157:Transcription Factors; C402111:WER protein, Arabidopsis