Abstract
Gibberellins (GA), plant hormone are large family of tetracyclic diterpenoids that are biosynthsized from ent-kaurene, the key intermediate of GA biosynthetic pathway. Recent studies proposed that GA act as plant hormone from the land plant lineage after the bryophyte divergence. The fern biosynthesize GA and has functional components of GID-DELLA gibberellin signaling. On the other hands, any GAs and functional GID and DELLA orthologues were not found in the moss P. patens. However, if physiologically active GA differs among the moss and higher plants, it would be possible that alternative GA-related diterpenes might work as active growth regulators of the moss. To assess the biological role of GA-related hormones in the moss Physcomitrella patens, the disruption of ent-kaurene biosynthesis in P. patens would be a straightforward approach. We performed the insertion knock-out of ent-kaurene synthase gene, PpCPS/KS in P. patens. The phenotype analysis demonstrate that Ppcps/ks Knock-Out plant has defect in the protonema development. This defects was recovered by an exogenous ent-kaurene and ent-kaurenoic acid application. Our results demonstrate that P. patens utilize diterpene metabolites synthesized from ent-kaurene as endogenous growth regulator.
