Stem Cell Quiescence and Dormancy in Plant Meristems.

Plants exhibit opportunistic developmental patterns, alternating between growth and dormancy in response to external cues. Moreover, quiescence plays a critical role in proper plant growth and development, particularly within the root apical meristem (RAM) and the shoot apical meristem (SAM). In these meristematic tissues, cells with relatively slower mitotic activity are present in the quiescent center (QC) and the central zone (CZ), respectively. These centers form long-term reservoirs of stem cells maintaining the meristematic stem cell niche (SCN), and thus sustaining continuous plant development and adaptation to changing environments. This review explores the early observations, structural characteristics, functions, and gene regulatory networks of the RAM and SAM. It also highlights the intricate mechanism of dormancy within the SAM. The aim is to contribute to a holistic understanding of quiescence in plants, which is fundamental for the plant proper growth and environmental response.