Molecular Cloning And Expression Analysis Of SOD Genes From Two Kinds Of Algaes

Superoxide dismutases (SODs) constitute the first line of cellular defenseagainst oxidative stress in plants. SOD sgenerally occur in three different forms withCu/Zn, Fe, or Mn as prosthetic metals. Laminaria japonica have importanteconomical and ecological values. Laminaria japonica undergoes fierce and rapidchange in physical parameters with the turning tides and alterations caused bydiurnal, seasonal, and meteorological variations.Therefore,it is meaningful to studythe mechanism of Laminaria japonica response to the ecological and environmentalstimulation.In this study, the cDNA of Laminaria japonica manganese superoxide dismutasegene (designated as LJMnSOD) and Haematococcus pluvialis iron superoxidedismutase gene(designated as HPFeSOD) were cloned by the combination ofhomology cloning and rapid amplification of cDNA ends (RACE) approaches. Thefull-length cDNA of LJMnSOD was of1199bp, including an open reading frame(ORF) of696bp encoding a polypeptide of232amino acids with predictedtheoretical isoelectric point of5.08and molecular weight of23.32kDa.The fulllength of HPFeSOD cDNA was isolated by5’RACE and3’RACE. The clone contains1138bp nucleotides with an open reading frame (ORF) of684bp comprising227amino acid residues.Under different stress conditions, messenger RNA(mRNA) expression levels ofHJMnSOD were quantified by quantitative RT-PCR. L. japonica gametophyte kept indifferent temperatures for4h, the expression level of HJMnSOD at30°C was highestand triple higher than that at10°C. L. japonica gametophyte were kept at25°C fordifferent times, after7h the mRNA expression level of HJMnSOD were reached amaximum level and then dropped progressively. The expression level of HJMnSODat0or5‰salt concentration for4h was twofold higher than that at30‰saltconcentration for4h. The results showed that dfferential expressions of HJMnSODunder different abiotic stressors.