The OsSRO1c-OsDREB2B complex undergoes protein phase transition to enhance cold tolerance in rice.

ABSTRACT

Cold stress is one of the major abiotic stress factors affecting rice growth and development, leading to significant yield loss in the context of global climate change. Exploring natural variants that confer cold resistance and the underlying molecular mechanism responsible for this is the major strategy to breed cold tolerant rice varieties. Here, we show that the natural variations of a SIMILAR to RCD ONE (SRO) gene, OsSRO1c, confer cold tolerance in rice at both seedling and booting stages. OsSRO1c possesses intrinsic liquid-liquid phase separation ability in vivo and in vitro and recruits an AP2/ERF transcription factor and positive cold stress regulator, OsDREB2B, into its biomolecular condensates in the nucleus, resulting in elevated transcriptional activity of OsDREB2B. The OsSRO1c-OsDREB2B complex directly responds to low temperature through dynamic phase transitions and regulates key cold response genes, including COLD1. Furthermore, introgression of an elite haplotype of OsSRO1c into a cold susceptible indica rice significantly increases its cold resistance. Collectively, our work reveals a novel cold tolerance regulatory module in rice and provides promising genetic targets for molecular breeding of cold-tolerant rice varieties.