Additional file 1: Fig. S1. (A-G) Gene expression associated with the drought tolerance pathway. (H,I) Interactions between IPA1 and the promoter fragments of OsNAC10 and OsNAC52, shown with yeast one-hybrid assays. Data are means ± se (n = 3). Statistical significance was determined by Student’s t-test. *, P < 0.05; **, P < 0.01. Fig. S2. Gene expression analysis of IPA1 in WT and OE lines. Data are means ± se (n = 3). Statistical significance was determined by Student’s t-test. *, P < 0.05; **, P < 0.01. Table S1. Primers used in this study.