Gibberellins (GAs) are the plant hormones controlling many aspects of plant growth and development in both vegetative and reproductive phases,e.g.germination,stem elongation,leaf expansion,flower initiation and fruit development.Various genes encoding the enzymes of the GA biosynthetic and metabolic pathway have already been isolated,and several studies have been reported on the control of plant growth and development by engineering this pathway.The GA 2-oxidase (GA 2ox) 2β-hydroxylate bioactive GAs or their immediate precursors to inactive forms or to products that cannot be converted to bioactive GAs,and therefore plays a direct role in determining the levels of bioactive GAs in plants.