Molecular Cloning And Expression Analysis Of A New Superoxide Dismutase Gene In Malus Xiaojinensis

The study isolated successfully a whole length superoxide dismutase gene by RT-PCR and screening the cDNA library from Malus xiaojinensis Cheng et Jiang. We named it MxSodl. Then we conformed an expression of MxSodl gene in E.coli, and analyzed expression pattern of the gene. The main results as follows:A superoxide dismutase gene cDNA sequence of Malus xiaojinensis Cheng et Jiang was isolated. The sequence is 826bp in length, and the deduced protein consists of 152 amino acids. The access number in Genbank is AY646367.Expression of MxSodl gene in E.coli was experimented. The structure of the recombinant expression plasmid had not base mutant and drift. SDS-PAGE of pET-MxSodl proteins showed that there was a strengthened protein band in expectant 20kDa protein Marker.A Southern blot experiment was performed and indicated that MxSodl has only a single copy in the genome of Malus xiaojinensis. But there are several same family genes of MxSodl in the genome of Malus xiaojinensis.A group of Northern blot experiment analyzed the expression patterns of MxSodl in Malus xiaojinensis. The MxSodl gene transcripts in almost all tissues but the transcription level has difference. The gene transcription level increases with leafage adding.Another group of Northern blot experiment analyzed the induced expression patterns of MxSodl under drought and salt stress. The results indicated that MxSodl expressed strongly in root and leaf under drought stress, however expressed in stem and leaf under salt stress. In three Genus Malus plants with different adversity-fastness, there were all two peaks of MxSodl gene transcript during the salt stress process. But they became at different time and with different length. This difference is exactly the exhibition of adversity-fastness.