Centromeric repeat diversity in hop

Aberrant meiosis in plants often leads to aneuploidy, genetic instability, and sterility. This can occur due to several factors, including chromosome misalignment, defective synapsis or environmental factors that may result in unusual genetic combinations in offspring. Unusual chromosome behavior during male meiosis in Humulus lupulus is linked to irregular chromosome segregation and genome instability. However, the origin of meiotic instability remains unclear. We analyzed the centromeric landscape of H. lupulus to determine its role in aberrant chromosome segregation. Using a combination of bioinformatic, molecular and cytogenetic approaches, we identified new centromeric repeats and revealed two types of centromeric organization. Cytogenetic localization on metaphase chromosomes confirmed the genomic distribution of major repeats and revealed unique features that contribute to aberrant segregation. Two centromeric types are composed of the major repeats SaazCEN and SaazCRM1 (Ty3/Gypsy) which are further accompanied by chromosome-specific centromeric satellites, Saaz40, Saaz293, Saaz85, and HuluTR120. Chromosome 2 displays unbalanced segregation, implicating an important role for its centromere structure in segregation patterns. Moreover, Saaz293 is a new marker for studying aneuploidy in hops. Our findings provide new insights on chromosome segregation in hops and highlight the diversity and complexity of the centromere organization in H. lupulus.