Bridging cells and stages: Plasmodesmata for the coordination of plant development

Plants are multicellular organisms in which numerous specialized cell types must communicate to function as a unified system. Plant cells are enclosed by rigid walls, and therefore, intercellular communication requires the presence of plasmodesmata (PD), cytoplasmic channels bridging neighboring cells. These structures are crucial for coordinating developmental stages across tissues. To ensure proper growth and development, the movement of signaling molecules, RNAs, proteins, and nutrients through PD must be tightly controlled, underscoring the importance of regulating their selectivity. Despite their essential role, direct evidence for PD involvement in developmental processes is limited and the mechanisms governing PD regulation remain incompletely understood. Recent studies suggest the existence of diverse regulatory mechanisms beyond the classical callose-based model, revealing a likely complex interplay of several PD regulators across development. In this review, we summarize recent findings on the role of PD in various plant developmental programs, discuss emerging regulatory mechanisms, and highlight how much remains to be discovered.