Wild cousins may help crops battle climate change

Date:
September 9, 2020
Source:
American Society of Agronomy
Summary:
Wild relatives of our domestic crops already cope with harsh
conditions and resist disease. Can we use them to help our preferred
crops adapt?


FULL STORY ========================================================================== Earth is getting hotter. Huge amounts of greenhouse gases are warming
the planet and altering the climate. Heat waves are harsher. Droughts
are longer.

And some diseases and pests are stronger than ever.


==========================================================================
All of that is bad news for many of Earth's inhabitants. But crops
are especially vulnerable. We've bred them to depend on us, and they
can succumb to many threats that are likely to get worse in the next
century. All as we need more food to feed a growing population.

An international group of researchers set out to test how we can help
our crops adapt in the coming decades. Their idea is to use wild crop relatives.

These cousins of domestic crops look like weeds and you have probably
walked past them when hiking on mountain trails. You may have even seen
them in the cracks of pavement in the cities. They have lived in harsh
climates without any human help since the dawn of time.

Scientists hope that using crop wild relatives in breeding programs can
add resilience to our domestic crops while keeping them delicious.

"Crop wild relatives have been selected by nature over millennia to
withstand the very climatic stresses that we are trying to address,
and hence present a new hope," says Filippo Bassi. Bassi is a scientist
in Morocco at the International Center for Agricultural Research in the
Dry Areas (ICARDA).



==========================================================================
But it can be risky to change how breeders work. "Before making the
final decision to shift investments from normal breeding to the use of
crop wild relatives, it is critical to make sure that there is a real
advantage in doing so," Bassi says.

To test this idea, Bassi's international team of scientists, coming from Africa, Europe, Asia and South America, focused on durum wheat.

The team gathered 60 unique varieties of wheat to expose to a battery
of harsh tests. These included fungal diseases, drought and high
temperatures. One-third of the wheat lines the team used were developed
by combining wild relatives of wheat with strong, commercial varieties.

These wild relative-derived varieties of wheat were robust compared to
more conventional varieties. About a third of wild relative varieties
were resistant to the fungal disease Septoria, compared to just a tenth
of the others. But conventional wheat varieties were more resistant
to other diseases, like leaf rust, that have been the focus of past
breeding programs.

Where the wild relative wheat varieties really shone was under drought
and heat stress. During drought, the wild relative lines had larger
grains, a critical adaptation and market trait for this crop. And,
when the nutrient nitrogen was in short supply, the wild-derived lines
produced a higher yield than the other wheat varieties.



==========================================================================
"In the case of temperature, the crop wild relative presented a clear
advantage with a yield increase of 42 percent under heat stress,"
says Bassi. "Yield losses to heat can be drastic, and the use of crop
wild relatives to breed new varieties appears to be a very strategic
approach to address this climatic challenge." But resilience isn't the
whole story. We depend on crops to make food. And crops are different
from their wild cousins in large part because humans have selected crops
over many centuries to adapt to their needs, including a preference for
making delicious foods.

That is why Bassi's team also looked at the usefulness of the 60 wheat varieties for making pasta. Here, the wild-derived wheat lines were
the least suitable for pasta making. "That's a disappointment," says
Bassi. "But not a deal breaker." "This does not prove that the use of
crop wild relatives will inevitably result in poor industrial quality,"
says Bassi. "But rather that it is important for breeders to be aware
of this risk and develop breeding strategies that address this issue."
Overall, durum wheat's wild relatives appeared useful. When crossed to
elite commercial varieties, they provided increased resistance to heat,
drought and some diseases. These are precisely the threats facing not
just durum wheat, but most major crops in a warming world. That's good
news for plant breeders -- and the public.

"The crop wild relatives showed great promise in terms of climate change adaptation," says Bassi. "I hope the public will be re-assured that
breeders are testing all possible opportunities to prepare agriculture
for climate challenges."

========================================================================== Story Source: Materials provided by American_Society_of_Agronomy. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Noureddine El Haddad, Hafssa Kabbaj, Meryem Zai"m, Khaoula El
Hassouni,
Amadou Tidiane Sall, Mounira Azouz, Rodomiro Ortiz, Michael Baum,
Ahmed Amri, Fernanda Gamba, Filippo Maria Bassi. Crop wild relatives
in durum wheat breeding: Drift or thrift? Crop Science, 2020; DOI:
10.1002/ csc2.20223 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/09/200909085940.htm

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