Regulation of shoot meristem integrity during Arabidopsis vegetative development.

Shoot growth and development is mediated by the activity of the shoot meristem, which initiates leaves and axillary meristems. Meristem maintenance is achieved by a poorly understood process that functions to sustain the balance of stem cell perpetuation in the central zone (CZ) and organogenesis in the peripheral zone (PZ). A recent study showed that two related homeodomain transcription factors, pennywise (PNY) and pound-foolish (PNF), regulate meristem maintenance by controlling the integrity of the CZ. The non-flower producing phenotype displayed by pny pnf plants can be rescued by genetically increasing the size of the shoot meristem. In this addendum, we show that augmenting the size of the central region of pny pnf shoot meristems partially rescues the meristem termination phenotype that occurs during early stages of vegetative development. Thus, regulation of CZ integrity by PNY and PNF is crucial for vegetative and reproductive development.