Transient restriction of intercellular communication is required for root tip regeneration

Cells of multicellular organisms rely on mobile signals to determine their identity. During organ regeneration, cells can undergo identity transitions to replace damaged tissues despite exposure to existing signals. To investigate how regeneration occurs within a patterned organ, we studied intercellular communication during the regeneration of the Arabidopsis root tip. We show that the movement of cell-to-cell signals is temporarily restricted near the injury site and that regeneration-induced lateral organ boundary domain (LBD) genes were required for this restriction. Mobile signals' distribution and de novo pattern acquisition were disrupted in high-order lbd mutants. However, regeneration capacity was restored by transient localized closure of plasmodesmata, the cytoplasmic channels connecting adjacent cells. Induced expression of LATERAL ORGAN BOUNDARY DOMAIN genes restricted cell-to-cell movement in uncut meristems and promoted callose deposition in multiple contexts, suggesting a broad capacity for regulating intercellular communication. We conclude that localized restriction of intercellular cytoplasmatic connectivity is essential for root tip repatterning during regeneration.