Diversity, regulation, and evolution of the gibberellin biosynthetic pathway in fungi compared to plants and bacteria

Bioactive gibberellins (GAs) are diterpene plant hormones that are biosynthesized through complex pathways and control diverse aspects of growth and development. GAs were first isolated as metabolites of a fungal rice pathogen, Gibberella fujikuroi, since renamed Fusarium fujikuroi. Although higher plants and the fungus produce structurally identical GAs, significant differences in their CA pathways, enzymes involved and gene regulation became apparent with the identification of CA biosynthetic genes in Arabidopsis thaliana and F. fujikuroi. Recent identifications of CA biosynthetic gene clusters in two other fungi, Phaeosphaeria spp. and Sphaceloma manihoticola, and the high conservation of CA cluster organization in these distantly related fungal species indicate that fungi evolved CA and other diterpene biosynthetic pathways independently from plants. Furthermore, the occurrence of GAs and recent identification of the first CA biosynthetic genes in the bacterium Bradyrhizobium japonicum make it possible to study evolution of CA pathways in general. In this review, we summarize our current understanding of the CA biosynthesis pathway, specifically the genes and enzymes involved as well as gene regulation and localization in the genomes of different fungi and compare it with that in higher and lower plants and bacteria. (C) 2009 Elsevier Ltd. All rights reserved.