ApGA20ox1, a key gibberellin biosynthesis gene, regulates somatic embryogenesis and plant height in Agapanthus praecox

•The main bioactive gibberellin controlling scape height in Agapanthus praecox is GA4.•ApGA20ox1 controls the biosynthesis of GA4 in Agapanthus praecox.•Suppression of ApGA20ox1 resulted in poor somatic embryogenesis potential in Agapanthus praecox.•ApGA20ox1 contributed to leaf elongation and plant height by affecting longitudinal cell length in Agapanthus praecox.•Suppression of ApGA20ox1 resulted in poor stress resistance traits in plant development of Agapanthus praecox.