Cloning And Functional Analysis Of Antifreeze Gene PicW From Picea Wilsonii

In this study, a cold-induced gene PicW was cloned from Picea wilsonii. The gene was669bp in length and without introns, the encoded protein contained222amino acids which were rich in alanine, threonine, glutamine, lysine and glutamic acid, but devoid of cysteine and tryptophan. The protein contained five repeated motifs homologous to the core K-segment in dehydrin. Protein secondary structure prediction showed that it comprised different amount of a-helix, mostly in the K-homologous segments, and random coils. The results above revealed the protein belongs to dehydrin family. PicW was sub-cloned into the plant expression vector PEZR(K)-LC and then transformed into tobacco. After treatment at-5℃for3h, all of the tobacco plants were wilting. However, the transgenic plants showed better growth turgor than wild-type plants. Further tests of physiological indices including relative electrolyte leakage, malondialdehyde content, proline and soluble sugar content also revealed significant differences between the wild-type and transgenic tobacco plants. It was concluded that the PicW has significant antifreezing function and the gene could be an important gene resource for freezing-tolerant plant breeding.