Stem cell maintenance in shoot apical meristems

Stem cell homeostasis in shoot apical meristems of higher plants is regulated through a dynamic balance between spatial regulation of gene expression, cell growth patterns and patterns of differentiation. Cell–cell communication mediated by both the local factors and long-range signals have been implicated in stem cell homeostasis. Here we have reviewed recent developments on spatio-temporal regulation of cell–cell communication processes with an emphasis on how ubiquitously utilized signals such as plant hormones function with local factors in mediating stem cell homeostasis. We also provide a brief overview of how the activity of ubiquitously utilized epigenetic regulators are modulated locally to orchestrate gene expression.

► CLV3 mediates internalization of CLV1 receptor and trafficking of CLV1 to lytic vacuoles leading to its degradation independently of CLV2, and CLV3 diffusion in SAMs may be widespread in SAMs.
► WUS acts as a hub in integrating cytokinin and auxin action to partition the SAM into distinct functional domains.
► WUS mediates transcriptional regulation through cis-element code involving two distinct binding sites.
► WUS coordinates both short-range stem cell specification event, and long-range cell division and differentiation events.