16.3.5—Gibberellin and gene activation

Gibberellin binds a receptor and initiates signalling that removes repression of target genes. In barley, this can activate amylase production; in stems, it can activate proteins associated with elongation.

The hormone changes gene expression rather than acting as a structural component of the growing tissue. Different targets and tissues explain why one hormone can produce distinct responses.

Adding gibberellin to an aleurone layer can increase amylase mRNA and enzyme activity, releasing soluble sugars from endosperm starch.

Gibberellin does not directly convert DNA into enzyme. It changes regulatory protein activity, which changes transcription of target genes.