This study detected the upstream and downstream key genes of glycolysis in Dunaliella Salina by using Real-time FluorescenceQuantitative PCR assays and measurement of enzyme activity. The results were as follows: the levels of transcription, enzyme activity, and protein of D. salina PFK were up-regulated under hyperosmotic stress while D. salina ENO were down-regulated. At the same time we monitored the change of intracellular degradation of starch, the synthesis of glycerol and PEP concentration in Dunaliella Salina under hyperosmotic stress. We found that lower expression of DsENO reduced the concentration of intracellular PEP which promoted the degradation of starch, and decreased the flow of carbon into the tricarboxylic acid cycle which would favor the synthesis of glycerol.

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The full-length cDNA of a Na(+) -dependent Pi transport gene (DsSPT1) in Dunaliella salina was cloned by 3' and 5' Rapid Amplification of cDNA Ends (RACE), with an open reading frame (ORF) encoding 716 predicted amino acids, which exhibited 60.5% identity to that of Na(+) -dependent Pi transport 1 (DvSPT1) from Dunaliella viridis. Hydrophobicity and secondary structure prediction revealed 11 conserved transmembrane domains similar to those found in DvSPT1 from D. viridis and PHO89 from Saccharomyces cerevisiae. The result of real-time quantitative PCR showed that expression level of DsSPT1 was enhanced at first and reached its peak at 90 min after salt stress; however, D. salina cells rapidly absorbed extracellular inorganic phosphorus which was determined by Inductively Coupled Plasma Mass Spectrometry (ICP-MS) during the first 5 min under salt stress. It suggested that D. salina on the absorption of inorganic phosphorus was regulated at DsSPTI posttranslational level.

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