Contamination and translocation of deoxynivalenol and its derivatives associated with Fusarium crown rot of wheat in Northern China

Fusarium crown rot (FCR) is one of the most important wheat diseases in Northern China. The main causal agent of FCR, Fusarium pseudograminearum, can produce mycotoxins such as type B trichothecenes. Therefore, FCR could be an additional source of mycotoxin contamination during wheat production. Field inoculation experiments demonstrated that FCR disease severity strongly impacts the distribution pattern of trichothecenes in different wheat tissues. Mycotoxins were mainly observed in lower internodes and a low amount was detected in the upper parts above the 4th internode. However, high levels of trichothecene accumulation were detected in the upper segments of wheat plants under field conditions, which would threaten the feed production. The variation of mycotoxin content among sampling sites indicated that besides disease severity, other factors like climate, irrigation, and fungicide application may influence the mycotoxin accumulation in wheat. A comprehensive survey of DON and its derivatives in wheat heads with FCR symptoms in natural fields was conducted in 80 sites of seven provinces in Northern China. Much higher levels of mycotoxin were observed than those in inoculation experiments. The mycotoxin content varied greatly among sampling sites, but no significant differences were observed if compared at province level, which indicated that the variation is mainly due to local conditions. Trace amounts of mycotoxin appeared to be translocated to grains, indicating that FCR infection in natural fields poses a relatively small threat to contamination of grains, but a larger amount to plant parts that may be used as animal feed. To our knowledge, this is the first report of trichothecene accumulation in wheat stems, heads, and grains following FCR infection in natural field condition. These investigations provide novel insights into food and feed safety risk caused by FCR in Northern China.