A Molecular Framework for the Embryonic Initiation of Shoot Meristem Stem Cells.
The establishment of pluripotent stem cells is a key event during plant and animal embryogenesis, but the underlying mechanisms remain enigmatic. We show that in the flowering plant Arabidopsis thaliana, expression of the shoot meristem stem cell marker CLV3 becomes detectable in transition stage embryos. Surprisingly, the key regulator of stem cell homeostasis WUSCHEL (WUS) is expressed but dispensable for stem cell initiation. Rather, the WUS paralog WOX2, a regulator of embryo patterning initiated in the zygote, functions in this process by shielding stem cell progenitors from differentiation. WOX2 upregulates HD-ZIP III transcription factors required for shoot identity and balances cytokinin versus auxin hormone pathways, revealing that classical plantlet regeneration procedures recapitulate the natural induction mechanism. Our findings link transcriptional regulation of early embryo patterning to hormonal control of stem cell initiation and suggest that similar strategies have evolved in plant and animal stem cell formation.
BIOSS Centre for Biological Signalling Studies, Faculty of Biology, University of Freiburg, Schänzlestrasse 1, 79104 Freiburg, Germany.
Zhongjuan
Z
Zhang
BIOSS Centre for Biological Signalling Studies, Faculty of Biology, University of Freiburg, Schänzlestrasse 1, 79104 Freiburg, Germany.
Elise
E
Tucker
BIOSS Centre for Biological Signalling Studies, Faculty of Biology, University of Freiburg, Schänzlestrasse 1, 79104 Freiburg, Germany.
Marita
M
Hermann
BIOSS Centre for Biological Signalling Studies, Faculty of Biology, University of Freiburg, Schänzlestrasse 1, 79104 Freiburg, Germany. Electronic address: laux@biologie.uni-freiburg.de.
Thomas
T
Laux
D017360:Arabidopsis / Q000166:cytology* / Q000187:drug effects / Q000196:embryology* / Q000235:genetics; D029681:Arabidopsis Proteins / Q000378:metabolism; D019521:Body Patterning / Q000187:drug effects / Q000235:genetics; D002454:Cell Differentiation / Q000187:drug effects / Q000235:genetics; D003583:Cytokinins / Q000494:pharmacology; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D017343:Genes, Plant; D007210:Indoleacetic Acids / Q000494:pharmacology; D018519:Meristem / Q000166:cytology* / Q000187:drug effects / Q000196:embryology* / Q000235:genetics; D012639:Seeds / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics*; D013234:Stem Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism; D014158:Transcription, Genetic / Q000187:drug effects
C118167:AT2G27250 protein, Arabidopsis; D029681:Arabidopsis Proteins; D003583:Cytokinins; D007210:Indoleacetic Acids; D014157:Transcription Factors; C525391:WOX2 protein, Arabidopsis
WUS-related homeobox transcription factor; auxin; cytokinin; embryogenesis; homeodomain-leucine zipper class III genes; shoot meristem stem cell