Santuari et al. (The Plant Cell, pages 2937–2951) reveal how the PLT gradient regulates cell state by region-specific induction of cell proliferation genes and repression of differentiation.
The cover image shows how PLT2 expression influences the boundary of meristem target gene expression domains at the root tip. Activation of ProHAN:3xvYFP expression in a transgenic root after 0, 6, and 24 h of DEX induction of PLT2-GR expressed under control of the constitutive 35S promoter. Ectopic induction is obvious at 6 and 24 h of transfer to DEX media from the enhanced expression of fluorescent protein throughout the root outside of the meristematic domain of endogenous PLT2 expression. This image series shows that PLT levels determine the proximal/shootward boundary of the target gene expression domain, consistent with a dose-dependent role in zonation.