Stress-responsive gene RsICE1 from Raphanus sativus increases cold tolerance in rice.
The ICE1 transcription factor plays a critical role in plant cold tolerance via triggering CBF/DREB1 cold-regulated signal networks. In this work, a novel MYC-type ICE1-like gene, RsICE1, was isolated from radish (Raphanus sativus L.), and its function in cold tolerance was characterized in rice. The RsICE1 gene was expressed constitutively with higher transcriptional levels in the roots and stems of radish seedlings. The NaCl, cold, and ABA treatments could significantly upregulate RsICE1 expression levels, but dehydration stress had a weak effect on its expression. Ectopic expression of the RsICE1 gene in rice conferred enhanced tolerance to low-temperature stress grounded on a higher survival rate, higher accumulation of soluble sugars and free proline content, a decline in electrolyte leakage and MDA levels, and higher chlorophyll levels relative to control plants. OsDREBL and OsTPP1, downstream cold-regulated genes, were remarkably upregulated at transcription levels in rice overexpressing RsICE1 under low-temperature stress, which indicated that RsICE1 was involved in CBF/DREB1 cold-regulated signal networks. Overall, the above data showed that RsICE1 played an active role in improving rice cold tolerance, most likely resulting from the upregulation of OsDREBL and OsTPP1 expression levels by interacting with the RsICE1 gene under low-temperature stress.