Fig. 1.

ZmbHLH128 and ZmbHLH129 homeologs bind the ZmC₄-NADP-ME promoter. (A) Schematic representation of the ZmC₄-NADP-ME promoter, divided into fragments used as baits in Y1H screenings, and the ZmbHLH TFs identified. ATG and TAG are the translational start codon and the stop codon of the ZmC₄-NADP-ME ORF, respectively. ZmbHLH position on the scheme indicates that they bind between the base pairs −389 and −154 in relation to the ATG. (B) Analysis of ZmbHLH-pZmC₄-NADP-ME binding specificity. Each of the six yeast bait strains was transformed with both ZmbHLHs (pAD-GAL4-2.1::TF vectors) and positive interactions selected on CM -HIS -LEU + 3-AT [yeast Complete Minimal medium lacking histidine and leucine amino acids, and supplemented with 3-amino-1, 2, 4-triazole (3-AT), a competitive inhibitor of the HIS3 gene product]. (C) Schematic representation of bHLH and ZIP protein domains, and respective position in protein sequences. (D) Schematic representation of ZmbHLH128 and ZmbHLH129 (black) and four additional maize homeolog gene pairs located in syntenic regions of chromosomes 4 and 5. Homeolog genes are indicated by colour. Arrows indicate direction of transcription of each gene. Genomic coordinates provided from the B73 RefGen_v3 assembly version.