Gibberella fujikuroi biosynthetic pathways

Figure 2. The GA biosynthetic pathway from, MVA to GAlsraldehyde. This pathway is found in the fungus Gibberella fujikuroi and higher plants...

The kaurenolides and fujenal that are formed by Gibberella fujikuroi are side products from the major biosynthetic pathway. Ent-kaurenoic acid is dehydrogenated to form ent-kaur-6,16-dienoic acid. Epoxidation on the p-face and hydrolysis afforded 7-hydroxykaurenolide (5.117), which was then hydroxylated at C-3 or C-18 to form the dihydroxykaurenolides. The unusual aldehyde anhydride fujenal (5.119) was formed via the 6p,7p-diol. Amongst the metabolites of Gibberella fujikuroi there are several compounds in which the 16-ene is hydrated to give a 16p-tertiary alcohol. These compounds are not metabolized further and represent a dumping mechanism . 

A simple method of screening for presumptive mutants of Gibberella fujikuroi is described. The use of one mutant (Bl-41a) in the elucidation of the gibberellin biosynthetic pathway from ent-kaurenoic acid and in the metabolism of substrate analogues is briefly reviewed. Some preliminary results are described on the investigation of the inhibition of individual biosynthetic steps by nitrogen in the medium. 

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