Trichothecene Chemotypes of Isolates of Gibberella zeae Recovered from Wheat in Argentina

REYNOSO, M.M.; RAMIREZ M.L.; LESLIE J.F.; CHULZE S.N.

Kansas City, Missouri

Conferencia; 2007 National Fusarium Head Blight Forum; 2007

U.S. Wheat and Barley Scabe Initiative

Wheat production in Argentina covers about 6.24 million hectares. Production reached 15 million tons during the 2006 harvest season, ranking Argentina as the fourth largest exporter in the world. The main pathogen associated with Fusarium Head Blight (FHB) in Argentina is Gibberella zeae (Schwein.) Petch (anamorph Fusarium graminearum Schwabe), which reduces both grain quality and yield. Wheat grains infected with G. zeae often are contaminated with a Type B trichothecene, usually deoxynivalenol (DON) or nivalenol (NIV), that is toxic to humans and domesticated animals. Strains of G. zeae usually express one of three sets of trichothecene metabolites (chemotypes): (i) nivalenol and acetylated derivatives (NIV chemotype), (ii) deoxynivalenol and 3-acetyldeoxynivalenol (3-ADON chemotype), and (iii) deoxynivalenol and 15- acetyldeoxynivalenol (15-ADON chemotype). Other Fusarium isolates that can produce both deoxynivalenol and nivalenol (NIV/DON) have been described and can not be assigned to any of these three chemotypes. We used a multiplex PCR assay to identify the trichothecene chemotype of 123 strains of G. zeae lineage 7 (identified by AFLP) isolated from  3 localities (San Antonio de Areco, Alberti and Marcos Juarez) within the main Argentinean wheat production area. Most (> 92%) of the Argentinean isolates of G. zeae had the 15-ADON chemotype, with the remainder having the NIV/DON chemotype. We did not detect the NIV or the 3-ADON chemotypes. Results from the PCR assays were consistent with those obtained by chemical analyses for all strains that produced trichothecenes. Knowledge of the chemotypes present in the G. zeae population is important when conducting mycotoxin surveys, implementing breeding programs, and identifying new and emerging populations of this fungal pathogen.