Biosynthetic studies on plant growth regulators in a moss Physcomitrella patens

Abstract

The moss Physcomitrella patens does not respond to active gibberellins （GAs）, and GAs have not been detected in the moss.　However, P. patens has a partial GA biosynthetic pathway that mediates the biosynthesis of the GA intermediate ent-kaurenoic acid （KA）.　Previous work demonstrated that P. patens KA-deficient mutants have defects in protonemal cell differentiation, which are restored by the application of KA but not by GAs.　Recently, I demonstrated that a KA-derived diterpenoid functions as a potent regulator of protonemal cell differentiation in the moss.　Bioassay-guided exploration with a KA-deficient mutant led to the detection of a bioactive metabolite from KA, and its structure was elucidated as ent-3β-hydroxy-kaurenoic acid.　Transcriptome analysis identified a gene encodes a putative 2-oxoglutarate-dependent dioxygenase involved in the oxidation of KA to ent-2α-hydroxy-kaurenoic acid, an inactive metabolite in protonemal cell differentiation.　My study showed that P. patens converts KA to an active form by 3-oxidation and to an inactive form by 2-oxidation, identifying a potential activation/inactivation system for GA biosynthesis in flowering plants.　Here I summarize the biosynthetic studies on GA-like plant growth regulators in a P. patens.