Secretory trafficking maintains the organelle band for spindle separation during Arabidopsis meiosis

Ploidy reduction is a critical aspect of meiosis, essential for the successful development of haploid germline cells. Notably, cellular processes during male meiosis vary between the major groups of flowering plants, with eudicots exhibiting simultaneous cytokinesis without an interkinesis phase, unlike monocots. Recent studies on the Arabidopsis jason (jas) mutant revealed that an organelle band plays a key role in spindle separation during simultaneous cytokinesis, though the mechanism is not fully understood. Here we identify a novel jas suppressor mutant, peleus (pele), which restores haploid pollen production in the jas background. PELE encodes a vacuole-localized protein that contributes to spindle separation by balancing the vacuolar pathway and secretory trafficking to the organelle band. JAS, PELE, and the ubiquitin-like protein UBQL coordinate the delivery of proteins and membrane components to the organelle band. Specifically, PELE and UBQL antagonistically fine-tune trafficking to the vacuole, while JAS adjusts the flow of secretory trafficking towards the organelle band. Our findings underscore the critical role of secretory trafficking in maintaining organelle band integrity and in ensuring precise spindle positioning during meiosis II. Our work provides novel insights into the regulation of the organelle band and spindle separation, enhancing our understanding of polyploidy generation in plants.