CRC1 confers heat tolerance by modulating meiotic DSB formation and repair in rice

SUMMARY CENTRAL REGION COMPONENT1 (CRC1), a key element of synaptonemal complex (SC) in rice ( Oryza sativa L.), plays a crucial role in meiotic double‐strand break (DSB) formation and repairing. However, its molecular functions remain incompletely characterized. In the present study, a thermosensitive low‐fertility mutant was identified, and the corresponding gene CRC1 was cloned using a MutMap+‐based approach. The mutant crc1‐t carrying a single‐base substitution in the AAA‐ATPase domain of CRC1 exhibited severely reduced fertility under high temperature, with partial restoration under normal conditions. Consistent with this observation, defects in bivalent formation in crc1‐t were also partially rescued at normal temperatures. Immunofluorescence analysis revealed a notable reduction in the foci of γH2AX, RPAla, DMC1, RAD51, HEI10, and ZEP1 on crc1‐t meiotic chromosomes, particularly under high temperatures, suggesting that normal temperature partially restores the meiotic DSB formation, repairing, and SC assembly in crc1‐t . Yeast two‐hybrid assays demonstrated that the interaction between CRC1‐T and P31 comet , ZEP1 and PAIR1 gradually weakened with rising temperature and were nearly abolished at 36°C, whereas the wild‐type CRC1 maintained stable interactions under the same conditions. These results imply that the non‐frameshift mutation in the AAA‐ATPase domain of CRC1 disrupts its protein partnerships under heat stress, leading to defects in DSB formation and DNA repair, thereby conferring thermosensitivity of crc1‐t . Our findings elucidate a mechanism by which CRC1 responds to temperature stress by modulating DSB dynamics and SC stability during rice meiosis.