A Molecular Framework for the Embryonic Initiation of Shoot Meristem Stem Cells

Publication date: 6 February 2017
Source:Developmental Cell, Volume 40, Issue 3
Author(s): Zhongjuan Zhang, Elise Tucker, Marita Hermann, Thomas Laux
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.

Graphical abstract

Teaser

Forming stem cells is a central task of embryogenesis. Zhang et al. demonstrate that WOX2 functions in initiating shoot meristem stem cells. WOX2 shields stem cell progenitors from differentiation by promoting the expression of HD-ZIP III transcription factors and ensuring the appropriate ratio of the phytohormones cytokinin and auxin.


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