May 25, 2012
Plant pathologists and chemists from The University of Western Australia, in collaboration with the CSIRO Plant Industry in Brisbane and the Department of Agriculture and Food Western Australia, have identified the mycotoxin profile associated with an isolated outbreak of Fusarium head blight (FHB) in south-western Australia in 2003. The findings highlight the ongoing potential threat to WA crops.
Up until now, outbreaks of FHB in WA have been infrequent and sporadic, in contrast with major outbreaks of FHB centered on eastern Australia, including in wheat crops in SE Queensland and northern New South Wales during the 2010-11 season.
Using fungal isolates obtained from the 2003 isolated outbreak of FHB in wheat in south-western Australia, UWA researchers have now published the first mycotoxin profile study from that outbreak in the paper “Mycotoxins produced by Fusarium spp. associated with Fusarium head blight of wheat in Western Australia”.
The study reveals the identity of the Fusarium spp. collected from this region during the FHB outbreak, confirming the associated pathogens to be F. graminearum in particular, and also F. acuminatum or F. tricinctum. The toxicity of their crude extracts from millet seed cultures to brine shrimp (Artemia franciscana) was associated with high mortality levels.
The main mycotoxins detected were type B trichothecenes (deoxynivalenol and 3-acetyldeoxynivalenol), enniatins, chlamydosporol and zearalenone, and this is the first time mycotoxin profiles for WA have been defined.
While such outbreaks of FHB reduce yield, most concern relates to greatly reduced marketability of grain with mycotoxin contamination. The milling, malting and brewing industries set very strict tolerances for Fusarium toxins in wheat and barley. Oats, triticale and rye are also susceptible to FHB.
Researchers warn that the situation in WA regarding FHB remains poorly defined in terms of distribution and toxigenicity of contributing Fusarium species. Links between outbreaks and weather variables are unexplored and no attempts have been made to develop or apply risk management tools needed by farmers, advisers, and grain exporters to manage FHB under current or future WA climate scenarios.
The researchers conclude that there is an urgent need for monitoring not just for the presence of the specific Fusarium spp. in any affected grain but also for their potential mycotoxin and other toxic secondary metabolites.
“In today’s competitive export markets, the cereal export industries in WA can ill-afford to continue to leave such issues unaddressed,” co-author from UWA School of Plant Biology and The UWA Institute of Agriculture Professor Martin Barbetti said.
This understanding of the range and types of myocotoxins produced from WA’s 2003 outbreak may also be relevant to regions with similar Mediterranean-type climatic conditions and cropping practices, such as South Africa, and other regions that may experience similar conditions to WA in future as a consequence of climate change.