Here, we cloned CRITICAL STERILITY-INDUCING TEMPERATURE 1 (CSIT1) that encodes an E3 ubiquitin ligase, and found that CSIT1 modulates the CSIT of thermo-sensitive genic male sterility 5 (tms5)-based TGMS lines through ribosome-associated quality control (RQC). CSIT1 binds to the 80S ribosomes and ubiquitinates abnormal nascent polypeptides for degradation in the RQC process.

 

Loss of function of CSIT1 inhibits the possible damage of tms5 to the ubiquitination system and protein translation and enhances accumulation of anther-related proteins such as catalase and suppresses abnormal accumulation of reactive oxygen species (ROS) and premature programmed cell death (PCD) in the tapetum, leading to a much higher CSIT in the tms5-based TGMS lines. Our findings thus reveal a mechanism regulating CSIT, providing insight into RQC and allowing better use of two-line hybrid breeding.