INMIBO ( EX - PROPLAME)   14614
INSTITUTO DE MICOLOGIA Y BOTANICA
Unidad Ejecutora - UE
artículos
Título:
Aggressiveness of Fusarium graminearum sensu stricto isolates in wheat kernels in Argentina.
Autor/es:
ALVAREZ, CL, SOMMA, S, MORETTI, A, FERNÁNDEZ PINTO,V.
Revista:
JOURNAL OF PHYTOPATHOLOGY-PHYTOPATHOLOGISCHE ZEITSCHRIFT
Editorial:
Blackwell Verlag
Referencias:
Año: 2009
ISSN:
0931-1785
Resumen:
ABSTRACT This study was designed to investigate the degree of aggressiveness of Fusarium graminearum sensu stricto isolates from Agentina and its relationship with trichothecene production. In order to charaterize Fusarium strains aggressiveness, disease severity was visually assessed as the percentage of spikelets bleached per ear. The severity ranged from a minimum of 27.19% seven days after inoculation to a maximum of 84.73% at 21 days of incubation  At maturity the ears were harvested and threshed for grain weight determination. All treatments showed significant differences in kernel weight respect to the control plants, with a yield reduction from 35% to 85% Grains infected by F. graminearum may contain significant levels of mycotoxins like trichothecenes. No correlation was found between aggressiveness and the toxins in the kernels at maturity, taking into consideration not only the quantity but also the type of toxin (nivalenol, deoxynivalenol or their acetylderivatives). Kernel weight reduction was a better estimator of the presence of Deoxynivalenol in the kernels than the Area Under the Disease Progress Curve (AUDPC) calculated with severity ratings. The Amplified Fragment Length Polymorphism (AFLP) technique was used to establish genetic relationships between 18 Argentinean isolates and 8 reference strains belonging to the Fusarium graminearum complex. The 18 F. graminearum isolates from Argentina grouped with the two F. graminearum s. str. reference isolates, with a similarity greater than 75%. The other reference strains belonging to the F. graminearum complex were clearly separated, with similarities ranging between 55 and 73%. The AFLP groups had no relationship with toxin accumulation on kernels or with the geographical origin of the isolates. Great heterogeneity was found in the AUDPC, yield reduction and toxin accumulation values across the regions.