Overexpression of a Multiprotein Bridging Factor 1 Gene DgMBF1 Improves the Salinity Tolerance of Chrysanthemum

Soil salinity represents a major constraint in the growth of chrysanthemum. Therefore, improving salinity tolerance of chrysanthemum has become an important research direction in tolerance breeding. Multiprotein bridging factor 1 (MBF1) is an evolutionarily highly conserved transcriptional co-activator in archaea and eukaryotes and has been reported to play important roles to respond to abiotic stresses. Here, a MBF1 gene induced by salt stress was isolated and functionally characterized from Dendranthema grandiflorum and name as DgMBF1. Overexpression of DgMBF1 in chrysanthemum increased the tolerance of plants to high salt stress compared to wild type (WT). It also showed fewer accumulations of hydrogen peroxide (H₂O₂), superoxide anion (O₂^-), higher activities of antioxidant enzymes, more content of proline and soluble sugar (SS) and more favorable K⁺/Na⁺ ratio than those of WT under salt stress. In addition, the expression level of genes related to antioxidant biosynthesis, proline biosynthesis, glyco-metabolism and K⁺/Na⁺ homeostasis was statistically significant higher in the DgMBF1-overexpressed lines than that in WT. These results demonstrated that DgMBF1 is a positive regulator in response to salt stress and could serve as a new candidate gene for salt-tolerant plant breeding.