Overexpression of RmICE1, a bHLH transcription factor from Rosa multiflora, enhances cold tolerance via modulating ROS levels and activating the expression of stress-responsive genes

Abstract

ICE1 (Inducer of CBF Expression 1), a MYC-like basic helix-loop-helix (bHLH) element for the transcribing process, is critical to plant cold response. However, the physiological function and regulatory mechanism of the ICE1 in woody flower plants remain unclear. In the present study, the functional characterization of RmICE1 from wild rose (Rosa multiflora Thunb.) was elucidated. The transcription levels of RmICE1 were affected by dehydration, salt and cold treatments. RmICE1 exhibited transcriptional activity, and the N-terminal was critical to its activity. RmICE1 over-expressed in tobacco improved the cold tolerance by higher proline content, lower electrolyte leakages (EL) and malondialdehyde (MDA) in contrast to wild-type (WT) plants at cold temperatures. Meantime, transgenic tobacco accumulated a significantly smaller amount of reactive oxygen species (ROS), complying with enhanced activity and expression levels of antioxidant enzymes after cold treatment in contrast to the WT. Besides, six genes stress-responsive genes in the transgenic lines exhibited higher expression levels of than the WT before and after cold stress. On the whole, as revealed from the mentioned data, RmICE1 could promote cold tolerance, probably, at least partially, because of the modulating process of ROS scavenging and the up-regulating process of stress-responsive genes.