Chemotypes, vegetative and mycelial compatibility and toxigenic capacity of Fusarium graminearum isolates of wheat from different areas of Buenos Aires province

ALVAREZ, C.; L. TERMINIELLO; D. CABRAL; V. FERNÁNDEZ PINTO

Mar del Plata, Argentina

Conferencia; 7th International Wheat Conference; 2005

Secretaría de Agricultura, ganadería, Pesca y Alimentación (SAGPyA) y el Instituto Nacional de Tecnología Agrícola (INTA)

Fusarium Head Blight (FHB), caused by Fusarium graminerum Schwabe (teleomorph Gibberella zeae), is one of the most important diseases affecting wheat cultivation. Not only result in severe yield losses but also causes reduction in quality and contamination of the grains by micotoxins. The introduction of new chemotypes of this pathogen through global commerce could increasing the problem all around the world and particularly in Argentina because of the large wheat cultivation area. The genetic variability in F graminerum has been scarcely studied and it is very important in order to look for isolates that could be used in Biological Control of FHB. Our objectives were to determine groups of vegetative Compatibility (VG) by nitrate non-utilizing mutants (Nit) and Mycelial Compatibility (MC) to establish the genetic variability present in the population and to correlate these groups with toxin production profile (chemotypes) and geographical origin of the strains. We analize 34 isolates from 16 places that were cultivated on SNA and PDA to  morphological characterization. The Nit mutants were obtained in Czapex-Dox medium amended with 3% KClO3 and the mycelial compatibility were evaluated in V-8 medium. The isolates were cultivated on rice to determine toxin production, extracted with acetonitrile-ethyl acetate –water (50:41:9) and detected by Gass Chromatography. All the strains presented the same morphology and growth capacities were different; the strains were gathered in 28 groups of VC. Usin MC, faster and easier to evaluate, 23 groups were obtained. These two results indicate great variability in the population. About the toxin production, 5 isolates produced only Deoxynivalenol (DON chemotype) and their acetyl derives; 7 produced DON, Nivalenol (NIV) and their acetyl derivates (DON-NIV chemotype): and two of them did not produce toxins. Until now, there were no correlation among chemotypes, CGs and geographical localization of the strains.