Isolation and functional characterisation of CDPKs gene from Arachis hypogaea under salt stress

One of salt-induced calcium-dependent protein kinases (CDPKs) gene was isolated from Arachis hypogeae L. by RACE method. The cDNA full length was 2241 bp deposited in GenBank (number KF437909), designated as AhCDPK. The coding region sequence of AhCDPK was 1629 bp and encoded a protein of 542 amino acids. The molecular weight and the theoretical isoelectric point of AhCDPK was 60.96 kDa and 5.61 respectively. Amino acid sequence analysis indicated that AhCDPK has highest similarity and homology with Glycine max L. In addition, the AhCDPK amino acids were predicted to encode a hydrophilic protein which localised in the endoplasmic reticulum. AhCDPK seemed to transcript in all peanut organs, and had the highest expression in seeds. The expression of AhCDPK could be strongly induced by both Ca2+ and NaCl. When exposed to salt stress, overexpressing AhCDPK in tobacco could alleviate PSII photoinhibition by improving physiological states, such as reducing the accumulation of reactive oxygen species (ROS), improving the activity of antioxidant defence system enzymes and improving the accumulation of osmotic regulation substance. These results showed that AhCDPK has the same functions as that of G. max, and it could play an important role for peanut to resist salt stress.