Cloning And Function Of ZjDREB2.2 Gene Of Zoysia Japonica

Zoysiagrass (ZoysiaWilld.), a type of perennial gramineous grass developing abundant rhizome and stolons, shows great resistance to multiple abiotic streses including drought, high salt and traffic, which endows it a wide usage for turf establishment. The molecular mechanism of stress tolerance in zoysiagrass is worthy of research. DREB type transcription factors in plants have been proved to play a key role during stress response by regulating the expression of multiple genes. In this study, using’Meyer’zoysiagrass as material, we cloned a new DREB2 gene and investigated its expression pattern and function. The main results are as follows:1. ZjDREB2.2 produced two transcripts, named ZjDREB2.2-S and ZjDREB2.2-L respectively. ZjDREB2.2-L contains an insertion of 50 bp that leads to a premature open reading frame (ORF). ZjDREB2.2-S has a complete ORF encoding 338 amino acids. The predicted protein has a molecular mass of 37297.6 and an isoelectric point (pI) of 4.86, and contains a typical AP2 DNA-binding domain from the 89th 10 the 145th in amino acid sequence. Phylogenetic tree analysis indicated that ZjDREB2.2-S was classified into the A-2 subgroup of DREB transcription factor group and was genetically close to homologous genes of sorghum and millet.2. In leaves, both ZjDREB2.2-S and ZjDREB2.2-L were expressed in normal growth conditions, and were up-regulated at a chilling temperature lower that 12℃, but showed no signifficent response to high salt or drought stress. During the 72h of 4℃-cold stress, the expresion of ZjDREB2.2-S was up-regulated moderately in leaves and substantially in stolons and roots. The expression of ZjDREB2.2-Lwas also induced in, but was reduced in roots.3. ZjDREB2.2-S cound bind to DRE elements specilally and activated the expression of the reporter genes of HIS3 and LacZ. When fused to the GAL4 DNA-binding domain, ZjDREB2.2-S could effectively function as a trans-activator in yeast. ZjDREB2.2-L did not show these activities.4. Plant expression vectors harbourning 35S promoter-driven ZjDREB2.2-S and ZjDREB2.2-L respectively, were constructed and used to transformed Arabidopsis plants by Agrobacterium tumefacience. A total of 17 ZjDREB2.2-S-transformed pants and one ZjDREB2.2-L transformed pants were identified by PCR. Phenotypes of dwarf, retardant growth and delayed florescence were observed only in the ZjDREB2.2-S-transformed plant.