Plasmodesmata dynamics are coordinated by intracellular signaling pathways

• Many proteins important for plasmodesmal transport do not localize to plasmodesmata.
• Signals from chloroplasts regulate plasmodesmata function and formation.
• Changes in plasmodesmal transport disrupt chloroplast function.
• Hundreds of plant transcription factors likely move cell-to-cell via plasmodesmata.
• Plasmodesmata play a prominent role in plant development and defense.

Membrane-lined channels called plasmodesmata (PD) connect the cytoplasts of adjacent plant cells across the cell wall, permitting intercellular movement of small molecules, proteins, and RNA. Recent genetic screens for mutants with altered PD transport identified genes suggesting that chloroplasts play crucial roles in coordinating PD transport. Complementing this discovery, studies manipulating expression of PD-localized proteins imply that changes in PD transport strongly impact chloroplast biology. Ongoing efforts to find genes that control root and stomatal development reveal the critical role of PD in enforcing tissue patterning, and newly discovered PD-localized proteins show that PD influence development, intracellular signaling, and defense against pathogens. Together, these studies demonstrate that PD function and formation are tightly integrated with plant physiology.