Fig. 3

DREB1A binds to AtTPPF promoter and acts as a transcriptional activator. a Transcript levels of AtTPPF in wild-type (WT) plants under drought conditions. b Transcript levels of DREB1A in WT plants under drought conditions. c Schematic diagrams of AtTPPF promoter and effector and reporter constructs used for yeast one-hybrid (Y1H) assays. Black circle indicates DRE/CRT “ACCGAC” cis-acting element in promoter. P1 indicates partial promoter fragment used to construct bait plasmid. d Results of Y1H assays and growth of yeast cells. Positive control: AtTPPF-P, full-length promoter (P) of AtTPPF, cotransformed with pJG4–5 empty vector; negative control: bait/pJG4–5, prey+bait, cotransformed with prey and bait on selective medium supplemented with X-Gal. e Schematic diagrams of effector and reporter constructs used in transactivational analyses. Promoter fragment P1 was inserted into reporter vector pGreen II 0800-LUC, and Renilla luciferase (REN) was used as control for activity normalization. DREB1A was inserted into pGreen II 62-SK expression vector. f Transient expression analysis of DREB1A. Transient expression assay in tobacco (Nicotiana benthamiana) to examine interaction between DREB1A and AtTPPF promoter. Promoter activities, (LUC:REN ratio) in tobacco leaf discs cotransformed with effector and reporter constructs. Control, LUC:REN ratio in leaf discs transformed with an empty vector (pGreen II 62-SK/pGreen II 0800-LUC). Statistically significant differences were determined by Student’s t test (p < 0.05)