The effects of 2,4-dichlorophenoxyacetic acid (2,4-D), gibberellic acid (GA), and abscisic acid (ABA) on the morphogenesis of gametophytes of Lygodium japonicum growing as longer-than-broad biplanar plates in red light and as broader-than-long biplanar plates in blue light were studied. Addition of 2,4-D or GA to the medium induced a change in the form of gametophytes from biplanar to filamentous in red light. Gametophytes growing in a medium containing 2,4-D in blue light were longer than broad, very much like gametophytes growing in the basal medium in red light. Although ABA generally retarded the growth of gametophytes in both light regimes, its presence in a medium containing 2,4-D nullified the effect of the latter, causing gametophytes to become plate-like in red light and short and stunted in blue light. Changes in the morphology of gametophytes induced by growth hormones were accompanied by corresponding changes in their length:width ratio and cell number.
Brassinosteroids repress the seed maturation program during the seed-to-seedling transition