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the international nature of
underlying the performance of elite crop varieties is an international network matching
plant genetic traits to the challenges of farming in dry, hot, frosty, salty or other
problematic growing conditions. Through this network, which includes a range of gene
banks, opportunities to improve crops flow to researchers and breeders around the world.
ACIAR works to facilitate the flow of material, which is especially important to Australia,
where cropping industries are unusually dependent on exotic, imported species.
by dr GIo brAIdottI
n 1999 wheat crops in Uganda failed when
a devastating disease long considered
under control—stem rust—re-emerged in
a more virulent form, which was to become
known as Ug99. The breakdown of wheat’s
immunity alarmed the world as the fungal
disease inevitably spread along well-worn
routes—to Kenya, Ethiopia, Sudan and Yemen.
The cause was the breakdown of the
genetically based resistance built into
wheat varieties in the 1950s—traits that
were a cornerstone of the Green Revolution,
protecting 90% of the world’s wheat varieties
and 20% of the world’s total calorie intake.
But in Uganda the stem rust fungus
re-jigged its DNA, trying out new genetic
possibilities, and found a way to break down
wheat’s in-built resistance. The resistance
breakdown occurred at a time of declining
interest and investment in agricultural science
in the developed world.
It was Nobel laureate Norman Borlaug,
nearing the end of his life, who raised the alarm
and philanthropist Bill Gates who provided the
funds to launch a response in the form of the
Borlaug Global Rust Initiative (BGRI).
The BGRI is a research network that makes
the best use of existing resources, funding
researchers with specialist rust expertise
wherever they exist. It developed facilities
to screen the susceptibility of the world’s
wheat varieties and to screen for resistant
germplasm in Kenya, where Ug99 is prevalent.
Breeders at the International Maize and Wheat
Improvement Center (CIMMY T) then played
a pivotal role, releasing Ug99-resistant wheat
cultivars to affected nations funded by donors
that included ACIAR.
However, breeders know that inevitably
the stem rust fungus will evolve. The genetic
recoding will continue to erode away any
new sources of resistance in wheat as part
of a perpetual ‘arms race’ between fungi
virulence and the immunity that breeders build
Throughout the Ug99 response, Australia was
the global ‘black sheep’. First, Australia’s problems
with rust disease are so pervasive and potentially
devastating that rust has long been a research
priority and it received additional funding from
ACIAR and the Grains Research and Development
Corporation (GRDC) to deal with Ug99.
Second, the stem rust resistance built into
Australian varieties often differed from the rest
of the world (due to considerations for grain
quality), with breeders preferring resistance
traits (such as Sr2) that retained wheat’s
effectiveness against Ug99.
Third, rust researchers at the University of
Sydney Plant Breeding Institute (PBI) in Cobbity
and CSIRO Plant Industry are looking for a way
off the rust merry-go-round by taking rust
resistance to a new, more durable level.
A crucial stepping stone towards this
important objective involves isolating rust
resistance genes and decoding the mechanism
of action at the molecular level.
That goal was achieved in 2013 when a
team led by Dr Evans Lagudah at CSIRO Plant
Industry announced the isolation of Sr33—a
stem rust resistance gene targeted because of
its unusual ability to defend against all stem
rust races tested, including Ug99. Sr33 can
interact synergistically with other resistance
genes (such as Sr2) to further raise the overall
level of protection available to a wheat crop.
The importance of biodiversity
like many plant genes of agronomic
importance, Sr33 does not originate from
the genome of domesticated plants. Rather
it comes from a wild relative of wheat—a
line of goatgrass (Aegilops tauschii) collected
in Iran. It is a classic example that highlights
the importance of collecting, conserving,
sharing and exploiting the world’s crop
genetic resources and of organisations, such
as ACIAR, that promote these ideals.
Dr Tony gregson, an Australian farmer
and former chairman of Bioversity
International, says ACIAR’s influence played
an important role in developments such as
the establishment of the Svalbard global
Seed Vault and the International Treaty
on Plant genetic Resources for Food and
Agriculture. The treaty, which was ratified by
Australia, implemented a multilateral system
of access and benefit-sharing of genetic
resources for 64 of the most important food
and forage crops.
Important techniques to exploit these
resources have also been developed
with ACIAR assistance. This includes FIgS
(Focused Identification of germplasm
Strategy), a technique that exploits
information about the seasonal agro-
climatic conditions where seed is collected
to better select material likely to contain
important traits. This includes the frost
tolerance recently identified in field peas by
Australian breeders from material collected
in China by Dr Bob Redden while on an
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