Figure 9.

Participation of O1 in late-stage phragmoplast guidance. The cortical division site is initially marked by the PPB and later by division site markers such as TAN1 and POK proteins (which are also present in the phragmoplast). In wild-type cells, the phragmoplast is guided to the division site by actin filaments and myosin VIII (Wu and Bezanilla 2014). After meeting the cortex, the phragmoplast continues to expand and interactions are stabilized by microtubules (Bellinger et al. 2021). In wild type, the phragmoplast fuses with the existing cell wall along the established division site, which is mediated by POK, TAN, and O1. In o1 mutants, after initial contact the phragmoplast becomes misguided, resulting in abnormal division planes.