Aggressiveness and Deoxynivalenol production of Fusarium graminearum isolates from different inoculum sources

CECILIA A. MOURELOS; ISMAEL MALBRÁN; PEDRO A. BALATTI; QUIRICO MIGHELI; GLADYS A. LORI

Bordeaux

Seminario; 12th European Fusarium Seminar; 2013

Institut national de la recherche agronomique

Fusarium head blight (FHB), caused by Fusarium graminearum Schwabe, is one of the most important fungal diseases affecting wheat. In addition to the severe yield and quality losses the disease causes, trichothecene contamination of infected grains poses a serious threat to human and animal health. In Argentina more than three quarters of the total arable land is cultivated under no-tillage. Large quantities of crop residues remain on the soil surface, representing the principal reservoir of F. graminearum. Furthermore, in the southern hemisphere the presence of weeds in the field throughout the entire year has proven to be of epidemiological importance as an inoculum source for FHB development. The aim of this work was to analyze aggressiveness towards wheat of F. graminearum isolates from different sources. Thirty-three isolates obtained from crop residues and symptomless inflorescences of gramineous (GW) and non-gramineous weeds (N-GW) were identified as F. graminearum based on their morphological and cultural characteristics, and confirmed by species-specific PCR. Aggressiveness of the isolates and FHB effect on thousand kernel weight (TKW) were tested by point inoculation (PI) of field grown wheat spikes. Inoculated spikes were hand threshed, grains were ground and DON was quantified by means of the RIDASCREEN® FAST DON ELISA kit (R-Biopharm). All isolates induced FHB symptoms on the spikes and accumulated DON in the grains. The isolates obtained from GW differed significantly in aggressiveness from those from N-GW (F=4.78, p