Accurate chromosome segregation is more dependent on kinetochore-bound Stu2 in meiosis than mitosis

Accurate chromosome segregation requires bipolar kinetochore-microtubule attachments. Error correction mechanisms promote cycles of kinetochore-microtubule release and reattachment until bipolar attachments are established. Although conserved error correction pathways operate in mitosis and meiosis, whether they have distinct requirements during meiosis remains unclear. Here, we investigate the role of Stu2/XMAP215/chTOG in kinetochore-microtubule error correction and compare its function with that of Ipl1/Aurora B during budding yeast mitosis and meiosis. Reducing kinetochore-bound Stu2 causes substantially more chromosome missegregation during meiosis than mitosis, revealing a heightened requirement for Stu2-mediated error correction. Whereas Ipl1-depleted cells fail to release initial improper kinetochore-microtubule attachments, kinetochore-defective stu2 mutants undergo repeated error correction attempts yet missegregate chromosomes. Our findings reveal distinct but complementary functions for Ipl1 and Stu2. Ipl1 releases initial improper attachments, while kinetochore-bound Stu2 promotes the formation and stabilization of productive attachments and enables error correction attempts to establish biorientation. We propose that features of meiotic chromosome segregation increase the requirement for multiple error correction pathways.