To dissect the molecular mechanisms underlying drought tolerance (DT) in rice, transcriptome differences of a DT introgression line H471, the DT donor P28 and the drought sensitive recurrent parent HHZ under drought stress were investigated using deep transcriptome sequencing. Results revealed a differential constitutive gene expression prior to stress and distinct global transcriptome reprogramming among three genotypes under time-series drought stress, consistent with their differential genotypes and DT phenotypes. Overall design: DT introgression line H471, the DT donor P28 and the drought sensitive recurrent parent HHZ under drought stress were investigated using deep transcriptome sequencing.The drought stress treatment was started by withholding water at the tillering stage. The days were counted after the AWC in the soil reached 20% to allow drought measurements at precisely determined intervals, and the soil water content reached 15%, 10% and 7.5% after 1d, 3d and 4d drought treatment, respectively.Three top leaves for each sample were harvested for each genotype under 1d and 3d drought stress and control conditions. All samples were immediately frozen in liquid nitrogen and stored at -80Â°C and then for transcriptome sequencing.