Onion AcCDF4 ectopia overexpression regulates flowering and abiotic stress response in Arabidopsis

Cycling Dof factors (CDFs) belong to DNA-binding with one finger (DOF) transcription factors family involved in multiple aspects of plant development and abiotic stress tolerance. In this study, an onion (Allium cepa L.) DOF gene was identified and named AcCDF4. The cDNA of AcCDF4 was 852 bp, encoding a 283 amino acid protein. AcCDF4 exhibited the highest expression in onion leaf before bolting and upregulated under cold and drought treatments. Here, we analysed the function of AcCDF4 in flowering regulation and abiotic stress response. Constitutively overexpressed AcCDF4 delayed the flowering time of cdf1 and cdf5 mutants in Arabidopsis by decreasing AtCO and AtFT expression. AcCDF4 delayed flowering when overexpressed in the Arabidopsis gi mutant. AcCDF4 transgenic lines showed better adaptability to cold stress with a higher survival rate, more fresh weight, and increasing AtCBF1 transcripts. Ectopically expressed AcCDF4 also promoted the drought tolerance of Arabidopsis with the reduction of electrolyte leakage and upregulation of AtGols2 expression. Overall, the results indicated that AcCDF4 might play a multifaceted role in flowering and abiotic stress tolerance.