Gibberellin biosynthesis: its regulation by endogenous and environmental signals.

The hormone gibberellin (GA) plays an essential role in many aspects of plant growth and development, such as seed germination, stem elongation and flower development. In recent years, exciting progress has been made in understanding how the biosynthesis of this hormone is regulated by endogenous and environmental factors. This has resulted from isolation of genes encoding enzymes involved in GA biosynthesis and metabolism, which also enabled us to manipulate the pathway by modifying the expression of these genes in transgenic plants. In addition, new GA response mutants provided information about how signaling components are involved in feedback regulation of the GA biosynthetic pathway.