Assessment of Fusarium infection in wheat heads using a quantitative polymerase chain reaction (qPCR)assay.

The accuracy of a quantitative polymerase chain reaction assay in quantifying the DNA of trichothecene-producing F. culmorum and F. graminearum within harvested wheat grains and head tissue was evaluated in comparison with incidences of infected kernels and deoxynivalenol levels. In a first experiment, six durum and bread wheat varieties were grown in randomized plots for a 2-year period, and inoculated with Fusarium macroconidia at six growth stages between heading and dough ripening, to obtain a wide range of Fusarium head blight incidences. There was a close relationship between fungal DNA and the amount of deoxynivalenol, and this relationship was consistent over Fusarium species, wheat species and varieties, and over a wide range of Fusarium head blight infection. In a second experiment potted wheat plants were grown under environmentally controlled conditions and inoculated with the two Fusarium species at full flowering; head samples were collected before inoculation and after 6 h to 12 days, and processed by the quantitative polymerase chain reaction assay. This assay made it possible to detect the dynamic of fungal invasion in planta after infection ..........