Fusarium toxins in Uruguayan wheat
1997
Pineiro, M. (Mycotoxin Dept. Montevideo (Uruguay). Technological Laboratory of Uruguay (LATU))
In Uruguay, Fusarium spp. (mainly F. graminearum) invade grain both in the field and in storage, and produce mycotoxins of which deoxynivalenol (DON) is the most prevalent. Under temperate and humid conditions, F. graminearum causes fusarium head blight (FHB, scab), adversely affecting crop development and grain quality. A three-year study was conducted in order to determine the natural occurrence of Fusarium toxins [trichothecenes (DON, Ac DON, NIV, FX, and T-2) and zearalone (ZEA)] in wheat and other priority grains in Uruguay. DON was the most abundant of the toxins detected with significant values in 47.7 percent of samples, and 15 Ac DON was the predominant isomer. ZEA was detected in 17.7 percent of samples. DON concentrations in wheat samples ranged from 80 to 1000 ppb. As 1994 was a prominent year for FHB of wheat in Uruguay, CIMMYT advanced breeding lines were evaluated for FHB susceptibility and mycotoxin content. The trichothecene with the highest incidence was DON, with levels of 80-2235 ppb. A direct relationship between disease severity and toxin concentration was not found based on the association of Fusarium field infection and DON content; however, high levels of DON were found only in heavily infected plants, and low toxin levels correlated with a lack of disease incidence in the field. The majority of the Chinese-origin lines showed high levels of FHB resistance combined with low trichothecene concentrations. These could be selected as scab resistant lines for future use in wheat improvement programs.
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