The OsSRO1c-OsDREB2B complex senses low temperatures to confer cold tolerance via direct regulation of COLD1 in rice

Cold stress is one of the major abiotic stress factors affecting rice growth and development, leading to great yield loss in the context of global climate change. Exploring superior natural variants that confer cold resistance and the underlying molecular mechanism is the major strategy to breed cold tolerant rice varieties. Here, we identified natural variations of a SIMILAR to RCD ONE (SRO) gene OsSRO1c that confers cold tolerance in rice at both seedling and booting stages. OsSRO1c interacts with transcription factor OsDREB2B and promotes its transcriptional activity by concentrating OsDREB2B into biomolecular condensates in the nucleus. The OsSRO1c-OsDREB2B complex directly sense cold stress through dynamic phase transitions in vivo and in vitro and regulate key cold response gene COLD1. Introgression of an elite haplotype of OsSRO1c into a cold susceptible indica rice can significantly increase its cold resistance ability. Thus, our work revealed a novel cold stress sensing module and provided a promising gene resource for breeding cold tolerant rice varieties. To search for downstream target genes of OsSRO1c-OsDREB2B complex under cold stress, we performed RNA-Seq analysis using ossro1c mutants, osdreb2b mutants and wild type ZH11 plants. Those genes down-regulated in both ossro1c mutants and osdreb2b mutants are candidates for OsSRO1c-OsDREB2B complex regulation under cold stress.