Source: USDA ARS
Agricultural Research Service (ARS) scientists are practicing "tough love" when it comes to preparing wheat for the climate challenges ahead.In
growth-chamber experiments in Peoria, Illinois, they're subjecting more than a
dozen varieties of this important staple cereal crop to a one-two punch of
stressors. The first comes from exposure to carbon dioxide (CO2) levels of up to 1,000 parts per million—an atmospheric concentration of the greenhouse gas that's projected for the turn of the century absent mitigation measures. The other stressor is infection by an insidious fungus known as Fusarium
graminearum. The
fungus, which thrives under warm, wet conditions, causes Fusarium head blight,
a costly disease of wheat, barley and oat crops worldwide that can damage the
grain and contaminate it with mycotoxins, rendering the grain unsafe for food
or feed use. Martha Vaughan, a
supervisory molecular biologist, and William Hay, a plant
physiologist, at the ARS Mycotoxin Prevention and
Applied Microbiology Research Unit in Peoria, are leading the
experiments to evaluate the resilience of different wheat varieties to these
stressors. Their
aim is to preempt a worrisome metabolic response of Fusarium head blight
resistant wheat plants to high CO2 levels: namely, a build-up of starch and other carbohydrates that corresponds to a drop in grain protein and mineral levels—especially phosphorus, calcium, zinc, iron and copper, which are important to human health and wellbeing. Results from the experiments also suggest that the loss of these nutrients can raise the risk of mycotoxin contamination and threaten grain end-use quality, potentially delivering an economic hit to both wheat growers and millers. Initially,
the scientists compared Alsen, a hard red spring wheat that carries two
commonly used genetic sources of blight resistance, to Norm, a popular high-yielding
but susceptible wheat variety. Alsen suffered a greater loss in grain
nutritional content than Norm, resulting in increased mycotoxin production by
certain Fusarium strains. In subsequent experiments, the researchers observed
similar responses in an additional nine resistant and six susceptible
varieties. For
the researchers, such results underscore a need for action on two key fronts. One is to systematically evaluate the high CO2 responses of U.S. wheat varieties that share the same genetic sources of resistance to blight—outbreaks of which are expected to worsen as global climate change conditions become more pronounced. The second course of action is to scrutinize existing collections of wheat germplasm or wild relatives of the cereal crop for traits that could be passed into affected varieties to bolster their climate-resiliency, preserving desired grain nutrient levels and blight
resistance. The
team also is studying how the fungus itself behaves in wheat plants exposed to
high CO2 levels, observing that:
- The severity of blight and production of
mycotoxins like deoxynivalenol depends on the fungal strain and wheat
variety attacked.
- Besides protein and minerals, Alsen plants
suffered a drop in oleic and linoleic fatty acids, which normally contribute
to resistance to blight and other fungal diseases.
Ultimately,
the team's findings will inform breeding efforts to shore up wheat's climate
resiliency and help guide growers to adopt crop management strategies that
could offset wheat's metabolic responses to high CO2 levels and, in turn, the
likelihood of mycotoxin contamination. "We
are currently working with a number of university wheat breeders to identify
climate-resilient, Fusarium head blight-resistant lines in order to address
this food safety and security issue," said Hay, whose ARS collaborators
include Vaughan, Susan McCormick, Milagros Hojilla-Evangelisa, Michael Bowman, Bob Dunn, Jennifer Teresi and Mark Berhow. The
team published its findings today in the journal Scientific Reports and
is preparing a second paper on the work. The Agricultural Research Service is
the U.S. Department of Agriculture's chief scientific in-house research agency.
Daily, ARS focuses on solutions to agricultural problems affecting America.
Each dollar invested in agricultural research results in $17 of economic
impact.
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