Functional framework of the kinetochore and spindle assembly checkpoint in Arabidopsis

The kinetochore, critical for accurate chromosome segregation and genome stability in eukaryotes, comprises the Constitutive Centromere Associated Network (CCAN) and the KMN network. In animals, the CCAN associates with centromeric nucleosomes throughout the cell cycle, while the KMN network assembles at kinetochores during M phase, binding spindle microtubules and serving as a platform for the spindle assembly checkpoint (SAC) complex. Despite conserved functions, kinetochore components vary across organisms. In this study, we investigated the subcellular localization and interaction maps of core kinetochore components in Arabidopsis (Arabidopsis thaliana). Of the four conserved CCAN components, we found that only Centromere protein C (CENP-C) localizes to kinetochores, while all KMN components consistently localize to the kinetochore throughout the cell cycle. Immunoprecipitation assays revealed interactions between core kinetochore proteins and regulators involved in DNA replication, histone modification, and chromatin remodeling, suggesting that the kinetochore may also function outside of M phase. Examining interactions between kinetochore and SAC components allowed us to elucidate plant-specific SAC localization mechanisms, providing a functional framework for understanding plant kinetochores and offering insights into SAC regulation in plants.