Nucleotide sequence alignment of the proximal regions of ppcA promoters from F. trinervia (C4, ppcA-Ft), F. bidentis (C4, ppcA-Fb), F. vaginata (C4-like, ppcA-Fv), F. brownii (C4-like, ppcA-Fbr), F. pubescens (C3–C4, ppcA-Fpub), F. cronquistii (C3, ppcA-Fc) and F. pringlei (C3, ppcA-Fp). Identical positions in all ppcA sequences are marked by an asterisk. The intron sequences in the 5' untranslated leader regions are marked by grey nucleotides. The start site of the F. trinervia ppcA transcript is indicated by an arrow, the TATA-box by a yellow box, the putative MYB-binding site by a blue box, and the CCAAT-sequences by a green box. Fragments of the F. trinervia ppcA1 promoter that interact with the FtHB proteins in the yeast one-hybrid system [14, 15] are marked by red bars. The translational ATG start codon is indicated by green nucleotides.