The wheat HO1 gene. Alignment of TaHO1 with other plant HO1s. Dark shading with white letters and gray shading with black letters reveal 100% and 75% sequence conservation, respectively. Database accession numbers are ADG56719 for TaHO1 (Triticum aestivum), AB021858 for AtHO1 (Arabidopsis thaliana), GU390397 for BnHO1 (Brassica napus), AF320024 for GmHO1 (Glycine max), AF320028 for LeHO1 (Lycopersicon esculentum), EU781632 for OsHO1 (Oryza sativa), AF276228 for PsHO1 (Pisum sativum), and EU962994 for ZmHO1 (Zea mays), respectively. Solid frame means signature sequence. Also, the arrow identified the predicated cleavage site between the transit peptide and mature protein. The conserved histidine residue involved in heme-iron binding and catalysis was shown by a white diamond. The conserved histidine residue for protein stability was illustrated by a reverse triangle.