title: Shoot apical meristem function in Arabidopsis requires the combined activities of three BEL1-like homeodomain proteins.
abstract: In plants, most of the above-ground body is formed post-embryonically by the continuous organogenic potential of the shoot apical meristem (SAM). Proper function of the SAM requires maintenance of a delicate balance between the depletion of stem cell daughters into developing primordia and proliferation of the central stem cell population. Here we show that initiation and maintenance of the Arabidopsis SAM, including that of floral meristems, requires the combinatorial action of three members of the BELL-family of TALE homeodomain proteins, ARABIDOPSIS THALIANA HOMEOBOX 1 (ATH1), PENNYWISE (PNY) and POUND-FOOLISH (PNF). All three proteins interact with the KNOX TALE homeodomain protein STM, and combined lesions in ATH1, PNY and PNF result in a phenocopy of stm mutations. Therefore, we propose that ath1 pny pnf meristem defects result from loss of combinatorial BELL-STM control. Further, we demonstrate that heterodimerization-controlled cellular localization of BELL and KNOX proteins involves a CRM1/exportin-1-mediated nuclear exclusion mechanism that is probably generic to control the activity of BELL and KNOX combinations. We conclude that in animals and plants corresponding mechanisms regulate the activity of TALE homeodomain proteins through controlled nuclear-cytosolic distribution of these proteins.
authors.affiliation: Department of Biology, Utrecht University, The Netherlands.
authors.forename: Bas
authors.initials: B
authors.lastname: Rutjens
authors.forename: Dongping
authors.initials: D
authors.lastname: Bao
authors.forename: Evelien
authors.initials: E
authors.lastname: van Eck-Stouten
authors.forename: Marco
authors.initials: M
authors.lastname: Brand
authors.forename: Sjef
authors.initials: S
authors.lastname: Smeekens
authors.forename: Marcel
authors.initials: M
authors.lastname: Proveniers
mesh_terms: D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism*; D018519:Meristem / Q000502:physiology*; D055503:Protein Multimerization; D012097:Repressor Proteins; D014157:Transcription Factors
chemical_list: D029681:Arabidopsis Proteins; D018398:Homeodomain Proteins; D012097:Repressor Proteins; D014157:Transcription Factors; C487569:RPL protein, Arabidopsis; C092852:KNAT5 protein, Arabidopsis