The constitutive expression of Chrysanthemum dichrum ICE1 in Chrysanthemum grandiflorum improves the level of low temperature, salinity and drought tolerance

The quality and productivity of chrysanthemum are severely compromised by various abiotic stresses. Here, we describe the isolation of CdICE1 from Chrysanthemum dichrum using RACE PCR, which shared identical nucleotide of ICE1 ORF from Chrysanthemum grandiflorum variety 'Jinba'. CdICE1 contains a conserved bHLH domain, a nuclear localization domain, a S-rich motif and a ACT domain. The constitutive expression of CdICE1 in C. grandiflorum improved the tolerance of C. grandiflorum to low temperature/freezing, drought and salinity. When the transgene was inserted in the antisense direction, the expression of the endogenous ICE1 gene was down-regulated, and the level of the plant's sensitivity to abiotic stress increased. The level of expression of CgDREBa and CgDREBb, activities of superoxide dismutase and peroxidase and the proline content were enhanced in the sense transgenic lines, and lowered in the antisense ones under stresses. In conclusion, CdICE1 represents a promising candidate for a biotechnological approach to improve the level of crop abiotic stress tolerance. Key message Overexpression of CdICE1 in C. grandiflorum confers the stress tolerance via its regulation of CgDREB involved in the oxidative and osmotic homeostasis pathways.