Evolution of Gibberellin Biosynthesis: Insights from Bryophytes to Flowering Plants

Gibberellins (GAs) are a class of diterpenoid compounds that were originally identified as the causal toxins of rice seedling disease. GAs are phytohormones produced universally by plants, and more than 130 GAs have been isolated to date. Studies using rice and Arabidopsis have revealed the biosynthesis and inactivation pathways of GAs as well as their signaling mechanisms. However, as genome sequencing progressed, it was found that mosses, liverworts, and hornworts lacked certain genes encoding GA biosynthetic enzymes. Recent studies have revealed that partial GA biosynthetic pathways function in planta to biosynthesize bioactive substances that can be regarded as ancestral GA substances and to regulate their own growth. This review summarizes the current knowledge regarding the biosynthetic pathways of GA and ancestral GA substances.