In pre-mitotic plant cells, the division plane is established by the preprophase band (PPB), a cortical ring of microtubules and F-actin that disassembles before metaphase. In maize, PPB formation requires discordia1 (dcd1) and alternative discordia1 (add1). The phragmoplast (the plant cytokinetic machinery) then assembles as the spindle disappears and grows towards the cortical site previously marked by the PPB, organizing the cell plate to complete cytokinesis. In this study (Uyehara et al., 2024), Uyehara, Rasmussen and colleagues examine the division site-localized protein TANGLED1 (TAN1) in wild-type cells, and in dcd1 mutant cells and dcd1 add1 double mutant cells, which have partially defective or completely absent PPBs, respectively. The authors show that the disruption of PPB formation in dcd1 mutants leads to division plane positioning defects and to aberrant accumulation of TAN1 at new cell plate insertion sites. Furthermore, TAN1 is absent from the cortex in preprophase to anaphase dcd1 add1 cells, suggesting that it can be recruited later independently of PPB. In addition, in an opaque1 mutant, which lacks myosin XI, and in dcd1 cells treated with the actin polymerization inhibitor latrunculin B, TAN1 levels are reduced, indicating a role for myosin XI and actin filaments in TAN1 recruitment during telophase. Together, this work provides insights into the recruitment of TAN1 during cell divisions and suggests that TAN1 accumulation might reflect the assembly of ‘division-site modules’ with unknown roles in cytokinesis.
