A New CIPK Gene CmCIPK8 Enhances Salt Tolerance in Transgenic Chrysanthemum

Calcineurin B-like protein-interacting protein kinases (CIPKs) are a key protein family in plant to withstand stress and promote growth. In this study, we cloned a novel CIPK gene CmCIPK8 from chrysanthemum, which is localized to the cytoplasm. CmCIPK8 is a protein containing a highly conserved S_TKc domain and a NAF domain. The expression of CmCIPK8 was highly induced by salt stress. Under salt stress, the chlorophyll content and relative water content of transgenic chrysanthemum were markedly higher than WT. Meanwhile, the transgenic chrysanthemum also has a lower content of reactive oxygen species, stronger antioxidant enzymes activity, and lower peroxidation degree of membrane lipid, accompanied by more soluble sugar, soluble protein and proline content. In addition, transgenic chrysanthemum also has a lower relative electrical conductivity, higher K+/Na+ and Ca2+/Na+ ratios, stronger photosynthetic capacity and root activity. Further studies showed that CmCIPK8 might enhance the expression of ion transport-related genes. Taken together, these results suggest that CmCIPK8 may promote tolerance to salt stress.