Abstract
Growth of the aerial part of the plant is dependent upon the maintenance of the shoot apical meristem (SAM). A balance between the self-renewing stem cells in the central zone (CZ) and organogenesis in the peripheral zone (PZ) is essential for the integrity, function, and maintenance of the SAM. Understanding how the SAM maintains a balance between stem cell perpetuation and organogenesis is a central question in plant biology. Two related BELL1-like homeodomain proteins, PENNYWISE (PNY) and POUND-FOOLISH (PNF), act to specify floral meristems during reproductive development. However, genetic studies also show that PNY and PNF regulate the maintenance of the SAM. To understand the role of PNY and PNF in meristem maintenance, the expression patterns for genes that specifically localize to the peripheral and central regions of the SAM were examined in Arabidopsis (Arabidopsis thaliana). Results from these experiments indicate that the integrity of the CZ is impaired in pny pnf plants, which alters the balance of stem cell renewal and organogenesis. As a result, pools of CZ cells may be allocated into initiating leaf primordia. Consistent with these results, the integrity of the central region of pny pnf SAMs can be partially restored by increasing the size of the CZ. Interestingly, flower specification is also reestablished by augmenting the size of the SAM in pny pnf plants. Taken together, we propose that PNY and PNF act to restrict organogenesis to the PZ by maintaining a boundary between the CZ and PZ.
Highlights
Growth of the aerial part of the plant is dependent upon the maintenance of the shoot apical meristem (SAM)
We propose a model in which PNY and PNF regulate the integrity of the central region of the SAM by maintaining a boundary between the central zone (CZ) and peripheral zone (PZ), which restricts the allocation of cells into leaf primordial to the PZ
The frequency of meristem termination decreases as the shoots grow and mature, presumably due to an increase in meristem size, which may render the SAM to be less susceptible to termination
Summary
Growth of the aerial part of the plant is dependent upon the maintenance of the shoot apical meristem (SAM). To understand the role of PNY and PNF in meristem maintenance, the expression patterns for genes that localize to the peripheral and central regions of the SAM were examined in Arabidopsis (Arabidopsis thaliana). Results from these experiments indicate that the integrity of the CZ is impaired in pny pnf plants, which alters the balance of stem cell renewal and organogenesis. Results from this study indicate that STM and CLV proteins act in an opposite manner to regulate meristem maintenance and cell proliferation (Clark et al, 1996).
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
