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SESSION 3: PATHOGENESIS – EPIDEMIOLOGY AND POPULATION
GENETICS
P52 - Aggressiveness and deoxinivalenol production
of Fusarium graminearum isolates from different
inoculum sources
C. A. Mourelos 1 , I. Malbrán 1 , P. A. Balatti 1 , Q. Migheli 2 , G. A. Lori 1
1 Centro de Investigaciones de Fitopatología, Facultad de Ciencias Agrarias y Forestales, Universidad
Nacional de La Plata, 60 y 119, CC 31, (1900) La Plata, Buenos Aires, Argentina; 2 Dipartimento di
Agraria - Plant Pathology and Entomology Unit, Università degli Studi di Sassari, Via E. De Nicola 9, I
- 07100 Sassari, Italy.
E-mail: mouceci@yahoo.com.ar
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