Title: Genetic Basis for the 3-ADON and 15-ADON Trichothecene Chemotypes in Fusarium graminearum Authors
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: April 1, 2010
Publication Date: April 1, 2010
Citation: Alexander, N.J., Mccormick, S.P., Waalwijk, C., Proctor, R. 2010. Genetic Basis for the 3-ADON and 15-ADON Trichothecene Chemotypes in Fusarium graminearum [abstract]. 10th European Congress on Fungal Genetics. Technical Abstract: In some regions of the world, most strains of the wheat head blight pathogen Fusarium graminearum have one of two trichothecene mycotoxin production profiles (chemotypes), which are designated as 3-ADON and 15-ADON. In a defined medium, strains with the 3-ADON chemotype produce a trichothecene (3-acetyldeoxynivalenol) with an acetate at carbon atom 3 (C3) but not at C15, whereas 15-ADON strains produce a trichothecene (15-acetyldeoxynivalenol) with an acetate at C15 but not at C3. Despite this, strains with both chemotypes possess enzymatic activities necessary for production of trichothecenes with acetates at both C3 and C15, e.g. 3,15-diacetyldeoxynivalenol (3,15-diADON), suggesting the chemical modification responsible for the two chemotypes occurs near the end of the trichothecene biosynthetic pathway. Polymorphisms in the trichothecene biosynthetic genes TRI3, which encodes a C15 acetyltransferase, and TRI12, which encodes a transport protein, are used as genetic markers to distinguish between strains with 3-ADON and 15-ADON chemotypes. However, a causal relationship between TRI3/TRI12 and the chemotypes has not been demonstrated. Sequence analysis has revealed marked differences in the coding sequence of the esterase gene TRI8 in 3-ADON versus 15-ADON strains. To determine whether these differences can affect trichothecene chemotype, we examined the activity of TRI8 as well as TRI3. The data indicate that differences in activity of the TRI8 esterase, rather than the TRI3 acetyltransferase, are the basis of 3-ADON and 15-ADON chemotypes in F. graminearum.