Zoysia japonica MYC type transcription factor ZjICE1 regulates cold tolerance in transgenic Arabidopsis

Abstract ICE1 (Inducer of CBF Expression 1) is a regulator of cold-induced transcriptome, which plays an important role in plant cold response pathway. To enhance the cold tolerance of Zoysia japonica, one of the warm-season turfgrasses, it is helpful to understand the cold response mechanism in Zoysia japonica. We identified stress-responsive ZjICE1 from Zoysia japonica and characterized its function in cold resistance. Our results showed that ZjICE1 shared the typical feature of ICE homolog proteins belonging to a nucleic protein. Transactivation activity assay revealed that ZjICE1 binds to the MYC cis-element in the ZjDREB1’s promotor. The ZjICE1 overexpressed transgenic Arabidopsis showed enhanced tolerance to cold stress with an increase in SOD, POD, and free proline content and reduction in MDA content, and inducing the transcripts abundance of cold-responsive genes (CBF1, CBF2, CBF3, COR47A, KIN1, and RD29A). These results suggest that ZjICE1 is a positive regulator in Zoysia japonica plant during cold stress and can be a useful gene for the molecular breeding program to develop the cold tolerant zoysiagrass. Furthermore, the ZjICE1 also conferred resistance to salt and drought stresses, providing the better understanding of the basic helix-loop-helix (bHLH) gene family in abiotic stress responses.