A schematic overview of the Cross-Species meta-Analysis of progressive Drought stress at the reproductive stage (CSA:Drought) approach. Following selection of relevant microarray drought stress studies, raw data, from each species, was integrated into separate datasets using rank product analysis. This statistical method generated lists of up- and down-regulated genes based on their expression (i.e. rank) across the individual experiments within each species. Significantly differentially expressed genes (DEGs), were used for intra-species analysis to retrieve enriched gene ontology (GO) terms and to classify genes into functional pathways. Next, DEGs within each species were transformed to rice orthologs and the penalized Fisher method was used to combine P-value distributions across species meta-analysis. Finally, the shared drought-adaptive DEGs were characterized and their universal nature was validated in a fifth species that was not included in the meta-analysis.