Production of 3-acetylnivalenol by transgenic Fusarium graminearum expressing Tri13 of type A trichothecene-producer: participation of the encoded cytochrome P450 monooxygenase in type B trichothecene biosynthesis

Tri13 encodes a cytochrome P450 monooxygenase that catalyzes C-4 hydroxylation of some interme- diates in the biosynthesis of type A and type B trichothecenes. This work demonstrated that Tri13 (FsTri13 ) of Fusarium sporotrichioides, a typical type A trichothecene producer, can participate in the biosynthesis of type B trichothecenes. When FsTri13 was expressed in Fusarium graminearum that produces 3-acetylde- oxynivalenol (3-ADON) as an end product, 3-acetylnivalenol (3-ANIV) was newly detected in the liquid medium. Although 3-ANIV can easily be prepared enzymatically from nivalenol (NIV) by using recombinant trichothecene 3-O-acetyltransferase (TRI 101 ), there has been no conclusive report on the production of 3-ANIV in cultures of Fusarium strains. Possible biosynthetic pathway for production of 3-ANIV was suggested with regard to the function of Tri 8 , which is responsible for deacetylation of the side-chain O-acetyls in 3-ADON biosynthesis.