Fig. 2

Transcriptome analysis of differentially expressed genes (DEGs) during the drought stress in the roots of S. psammophila. a Harvest regime designed for a treatment-versus-control experiment with four time points (0, 6, 24 and 96 h) after 22% (w/v) polyethylene glycol 6000 (PEG 6000)-simulated drought stress. All treatments were started at different calculated times prior to the harvest day, and all root samples were designed to be harvested at the same time. b Principal component analysis (PCA) showing the uniformity between biological replicates and the relationships of samples at four stages. The PC1 and PC2 explaining 46.1 and 43.8% of the total variance, respectively. c Hierarchical cluster analysis of total DEGs. Columns and rows in the heat maps represent samples and genes, respectively. d The number of up- and down-regulated genes during drought stress with respect to the control or the preceding time point. e Venn diagram of DEGs showing common or uniquely regulated genes at different time points during drought stress