Rice OsRAD21-2 is expressed in actively dividing tissues and its ectopic expression in yeast results in aberrant cell division and growth

Rad21 and its meiotic counterpart Rec8, the key components of the cohesin complex, are essential for sister chromatid cohesion and chromosome segregation in mitosis and meiosis, respectively. In contrast to yeast and vertebrates, which have only two RAD21/REC8 genes, the rice genome encodes four Rad21/Rec8 proteins. Here, we report on the cloning and characterization of OsRAD21-2 from rice (Oryza sativa L.). Phylogenetic analysis of the full-length amino acids showed that OsRad21-2 was grouped into the plant-specific Rad21 subfamily. Semi-quantitative reverse transcription-polymerase chain reaction revealed OsRAD21-2 preferentially expressed in premeiotic flowers. Further RNA in situ hybridization analysis and promoter::β-glucuronidase staining indicated that OsRAD21-2 was mainly expressed in actively dividing tissues including premeiotic stamen, stem intercalary meristem, leaf meristem, and root pericycle. Ectopic expression of OsRAD21-2 in fission yeast resulted in cell growth delay and morphological abnormality. Flow cytometric analysis revealed that the OsRAD21-2-expressed cells were arrested in G2 phase. Our results suggest that OsRad21-2 functions in regulation of cell division and growth.