RESUMEN
This experiment was based on a full-length SAMDC sequence from the drought stress induced cDNA library of Cleistogenes songorica.Two methods,absolute quantification and relative quantification,were used to analyze the gene expression under different tissue and drought stress treatment by real-time quantitaive PCR experiments and were compared each other,while CsSAMDC gene was used as a case.Leaves and roots tissue were sampled from the plants at 0,4,6,8,and 10 d of drought stress and 1 and 4 d after rewatering.The 2-CT method was used to analyze the relative changes in gene expression from quantitative real-time PCR experiments.A standard curve was generated by the purified plasmid DNA.The primer concentration in the realtime PCR was optimized.All absolute quatification data were normalized by the normalization factor from the most stable house-keeping genes in C.songorica.Relative quantification results using 2-CT method showed that CsSAMDC transcripts increased 5.93?0.71 fold in roots,down regulated 0.62?0.13 fold in leaves,under drought stress.Absolute quantification results showed that CsSAMDC transcripts up-regulated in roots significantly under drought stress as 1ong as 8 to 1 0 days after drought stress,while down-regulated in both roots and leaves after drought stress within 6 days and 1 to 4 days after rewatering,compared with control.CsSAMDC transcipt showed similar tendency of gene expression compared by using relative and absolute quantification methods.