Fusarium graminearum sensu stricto chemotype distribution in the Argentinean wheat cropping area

ALVAREZ, CORA LILIA, FERNÁNDEZ PINTO VIRGINIA

Wheat Genetics, Crops and Food Production

Nova Science Publishers, Inc.

Lugar: Hauppauge, NY; Año: 2010;

Fusarium species are worldwide causal agents of Fusarium Head Blight (FHB) in cereals. Head Blight can not only reduce yield but also produce fungal toxins that seriously damage grain quality for human and animal consumption. Several studies have shown that F. graminerarum sensu stricto and deoxynivalenol (DON) are the main contaminants detected in wheat in Argentina. Chemotype characterization has been extensively used to characterize F. graminearum for its toxigenic potential. Many reports have shown differences over space and time of its chemotype distribution, suggesting that this approach is valuable to map a population and identify population changes in the field. The analysis of the trichothecene chemotype distribution of the F. graminearum sensu stricto strains across the Argentinean wheat cropping area has revealed that the 3-DON chemotype is always present. Differences in chemotype distribution may result in the shift in toxin accumulation in grains. However, no definitive proof on the correlation between chemotype detection and grain contamination has been found to date. This is mainly due to the variability of toxin production found among strains and to the fact that the samples analyzed have been taken from different origins and environmental conditions. Thus, the combination of genetic chemotyping with chemical analysis of toxin production is desirable. Many authors who have studied this important pathogen on wheat suggest the presence of only one population with high genetic variation in Argentina. Whether or not this variation implies differences in chemotype is an issue that needs further studies.  Another point of remarkable interest is the increase in the presence of other casual agents of FHB, such as F.  poae, a relatively weak pathogen compared with F. graminearum, but capable of producing a large number of mycotoxins, including type A and type B trichothecenes, beauvericin and enniatins. All these aspects show the need for a better knowledge of the population dynamics and distribution of the pathogens associated to wheat in the large production area of Argentina.