WITHDRAWN: Reversible phosphorylation of WOX5 protein controls the homeostasis of QC

Abstract

Fundamental questions of structural and functional homeostasis of QC in root stem cell niche of Arabidopsis remain elusive. As a QC marker, how the homeostasis of WOX5 protein regulated by post-translational modification remains unknown. Here, we characterize the role of a PEST domain in WOX5 protein, which stabilizes WOX5 protein by phosphorylated of GSK3 Motifs (GMs). Next, we demonstrate that the subfamily II of Arabidopsis SHAGGY-like Kinases (AtSKs) stabilizes WOX5 protein by phosphorylating the GMs in the PEST domain and the subfamily II of the catalytic subunit of Arabidopsis PP2A (AtPP2A-Cs) holoenzymes destabilizes WOX5 protein by dephosphorylating the GMs. Moreover, we found that in situ overexpressed and phosphate-mimicked WOX5 protein both produce more quiescent cells by reducing the proliferative activity of the original stele initials (SI) and its daughter cells (SID). Taken together, the homeostasis of WOX5 protein modulated by reversible phosphorylation functionally controls the homeostasis of low proliferative activity of QC, and the subfamily II of AtPP2A-Cs structurally controls the homeostasis of one-layer QC cells by down-regulating WOX5 expression and destabilizing WOX5 protein in the SI and SID.