Promoter study of OnTI1. Plasmids harboring various lengths of OnTI1 promoter fused with GUS were delivered to the lips and leaves of Oncidium Gower Ramsey. (A) The transformed tissues are stained to demonstrate GUS activity. The number on at the top is the length of the promoter. (B) Quantitative analysis of GUS activity. Orange boxes, the conserved regions II, III and IV of the OnTI promoter region. Oncidium alcohol acyl-transferase 500 bp promoter-GUS was used as the positive control, with the negative control being just the vector.