Abstract 
We identified the rice member of MTOPVIB/TOPOVIBL protein family and designated OsMTOPVIB. In the OsmtopVIB mutant, neither γH2AX nor OsDMC1 is properly loaded. Nevertheless, DSB repair defects in Osrad51c and Oshus1 are abolished in the OsmtopVIB background. These results reveal that OsMTOPVIB is required for DSB formation in rice meiosis. OsMTOPVIB interacts with OsSPO11-1 and OsSPO11-2, indicating that meiotic DSB is generated by a heterodimer as archaeal TopVIA/TopVIB.