Overexpression of PavbHLH28 from Prunus avium enhances tolerance to cold stress in transgenic Arabidopsis

Background: The basic helix-loop-helix (bHLH) gene family is one of the largest transcription factor families in plants. It plays an important role in the regulation of plant growth and abiotic stress response. Results In this study, we determined that PavbHLH28 gene participated in cold resistance. The PavbHLH28 gene was located in the nucleus and could be induced by low temperature. Under the treatment of ABA, PEG, and GA 3 , the transcript level of PavbHLH28 was affected. At low temperature, overexpression of the PavbHLH28 gene enhanced the cold resistance of plants with higher proline content, lower electrolyte leakage (EL) and malondialdehyde (MDA) content. Compared with the WT plants, the transgenic plants accumulate less reactive oxygen species (ROS), and the activity and expression levels of antioxidant enzymes were significantly increased. The expression of proline synthesis enzyme genes was up-regulated, and the transcripts levels of degradation genes were significantly down-regulated. The transcripts abundance of the cold stressed-related genes in the C-repeat binding factor (CBF) pathway were not significantly different between WT plants and transgenic plants after cold stress. Moreover, the PavbHLH28 can directly bind to the POD2 gene promoter and promote its gene expression. Conclusions Overall, PavbHLH28 enhanced cold resistance of transgenic plants through a CBF-independent pathway, which may be partly related to ROS scavenging.