Figure 7.

HY5 Is Responsible for NAC019 Transcription in FR.

(A) The induction of NAC019 transcription is attenuated only in the hy5 mutant upon FR. Four-day-old etiolated seedlings of the indicated genotypes were left in the dark (D) or exposed to FR for 3 h (FR3h), followed by qRT-PCR. The values of the NAC019 transcript were normalized to that of Actin. NS, not significant. Error bars represent sd (n = 3) of three biological replicates.

(B) Yeast one-hybrid assay showing that HY5, but not other tested transcription factors, binds to the G1 and G3 motifs on the NAC019 promoter. At top are diagrams of the wild-type and mutant NAC019 promoter fragments used to drive the expression of the LacZ reporter gene in yeast. Wild-type ACE and G-boxes are shown in red. Nucleotide substitutions for ACE (mACE) and three G-boxes (mG1, mG2, and mG3) are in lowercase. At bottom, mutation of the G1 and G3 motifs abolished the HY5 binding in the A and C regions, respectively, of the NAC019 promoter. The LacZ reporter driven by the PIL1 promoter was used as a positive control for transcription factors PIF1 and PIF3 in the yeast one-hybrid assay. AD, activation domain; FL, full length.