The IbmiRn01-IbSEN1-Ibcirc560 module regulates chilling tolerance in sweetpotato

Chilling stress is a major constraint on sweetpotato growth and yield. Understanding how sweetpotato perceives cold signals is therefore crucial for understanding the mechanisms underlying its ability to avoid chilling and maintain productivity under low-temperature conditions. In this study, we identified a novel chilling-induced microRNA, IbmiRn01, which enhances chilling tolerance by targeting and cleaving the transcript of IbSEN1, a member of the RNA helicase family. We found that IbSEN1 acts as a negative regulator of chilling tolerance. Transgenic plants overexpressing IbmiRn01, as well as those with RNA interference (RNAi) knockdown of IbSEN1, exhibited enhanced chilling tolerance, accompanied by the modulation of the expression of cold signaling-related genes, and increased antioxidant enzyme activities. In contrast, plants with a short tandem target mimic (STTM) of IbmiRn01 or overexpressing IbSEN1 displayed chilling-sensitive phenotypes. Further analysis revealed that IbSEN1 promotes the transcription of IbACD5 (accelerated cell death 5) and interacts with IbHSP90 (heat shock protein 90) to regulate chilling tolerance. Notably, IbSEN1 also significantly represses the expression of a circular RNA, Ibcirc560. Ibcirc560 overexpression increases sensitivity to chilling stress, likely through the upregulation of IbACD5 and IbHSP90 expression. Together, our results reveal a previously unrecognized regulatory module - the IbmiRn01-IbSEN1-Ibcirc560 network - that fine-tunes chilling tolerance in sweetpotato. These findings provide valuable genetic targets for molecular breeding aimed at improving chilling stress tolerance in sweetpotato varieties.