The bHLH transcription factor CgbHLH001 is a potential interaction partner of CDPK in halophyte Chenopodium glaucum

Plants have evolved different abilities to adapt to the ever-fluctuating environments for sessility. Calcium-dependent protein kinase (CDPK) is believed to play a pivotal role in abiotic stress signaling. So far, study on the specific substrates that CDPK recognized in response to adversity is limited. In the present study, we revealed a potential interaction between CDPK and a bHLH transcription factor under salt stress in Chenopodium glaucum. First, we identified a CgCDPK, which was up-regulated under salt and drought stress; then by Y2H screening, CgCDPK was detected to be involved in interaction with a bHLH TF (named as CgbHLH001), which also positively respond to salt and drought stress. Further computational prediction and experiments including GST-pulldown and BiFC assays revealed that potential interaction existed between CgCDPK and CgbHLH001, and they might interact on the plasma membrane. In addition, CgCDPK-overexpressed transgenic tobacco line could significantly accumulate transcripts of NtbHLH (a homolog of CgbHLH001 in N. tabacum), which provided another evidence of correlation between CgCDPK and CgbHLH001. Our results suggest that CgbHLH001 can interact with CgCDPK in signal transduction pathway in response to abiotic stress, which should provide new evidence for further understanding of the substrate specificity of plant CDPK signaling pathway.