Alcohol Dehydrogenase Gene ADH - Alcohol dehydrogenase gene expresses under anaerobic conditions leading to oxygen deprivation. Using transgenic plants, it could be shown that regulatory sequences upstream to ADH gene from maize lead to suppression (down regulation) of gene activity under aerobic conditions, this activity being normal and uninducible under anaerobic conditions.

The inability of the ADH upstream regulatory sequences to induce (these sequences only suppress) gene expression became evident when these sequences failed to induce chloramphenicol acetyl transferase (CAT) expression under aerobic as well as anaerobic conditions in transgenic tobacco plants.