Complete issue - IMA Fungus

NEWS
World distribution of Puccinia graminis race Ug99 on wheat (November 2011). Courtesy Borlaug Global Rust
Initiative.
2. Australia:
• Oct-­‐Nov 2010: Consistent air-­flows
from South Africa
• Confirmed Ug99 (race PTKST:
Sr31+Sr24 vir.) at source
• Abnormal rainfall in Australia
• SuscepMble hosts in Australia
Emerging Concerns
and identified varieties of wheat that show
Ug99 resistance in efforts to prepare for the
possibility of a Ug99 outbreak in the USA.
The Durable Rust Resistance in Wheat
(DRRW) project, funded by the Bill &
Melinda Gates Foundation and the UK
Department for International Development,
and administered at Cornell University,
has been established with the mission to
mitigate this threat to the world’s wheat
crop and avoid catastrophic losses. Two
important DRRW objectives are pathogen
surveillance and breeding wheat varieties
that are resistant to the family of stem rust
that includes Ug99, as well as stripe rust
Jan-­‐Mar 2011
Oct-­‐Nov 2010
1. South Asia:
• Jan-­‐Mar 2011: Consistent air-­flows
from Yemen + Eritrea
• Stem rust (Ug99?) at source in
Yemen, Feb 2011
• High severity of stem rust
Eritrea, Oct. 2010
• Highly suscepMble hosts in
South Asia (PBW343: 6M ha;
Inqualab-­‐91: 4M ha)
Possible spread of Puccinia graminis race Ug99 on wheat. Prepared by David Hodson (CIMMYT).
(P. striiformis, syn. P. glumarum). New
cultivated varieties must also improve
farmers’ yields to keep pace with a growing
world population.
Ug99 is highly mobile, carried by wind
or accidental human transmission. Because
it does not recognize political boundaries,
a surveillance system that is global in
scope is necessary. The Global Cereal Rust
Monitoring system is a coordinated network
of national surveillance teams who collect
standardized data from wheat fields in 20
countries in Africa and Asia. The surveyors
note any instance of rust, collect a sample
of the rust for genetic testing, and record
GPS data and other factors. These data are
incorporated into a centralized database
which allows researchers a bird’s eye view
of the track of the pathogen, which helps in
predicting where it might go next.
Since its discovery in Uganda, Ug99
has spread north-easterly through Kenya,
Ethiopia, crossed the Red Sea into Yemen
and Iran, and is now currently threatening
Pakistan (where 24 M tons of wheat were
produced in 2009) and India (over 80 M
tons). Both countries have large plantings
of wheat that are known to be susceptible.
Historical evidence of the movements of
rust pathogens indicates that Pakistan and
India are at-risk. Ug99 has also traveled
south, down the eastern coast of Africa to
South Africa. There is a chance it could
travel via wind currents over the Indian
Ocean into Australia.
Screening nurseries in Kenya and
Ethiopia are key to the resistance breeding
efforts. The nurseries are administered
by CIMMYT (International Maize and
Wheat Improvement Center), KARI
(Kenya Agricultural Research Institute), and
EIAR (Ethiopian Institute of Agricultural
Research). Because Ug99 is present in east
Africa, breeders from countries where Ug99
is not present send promising new wheat
varieties to these nurseries for field testing.
Wheat breeders at the nurseries plant the
seeds, expose them to Ug99, and collect
screening data based on the incidence and
severity of infection. If a variety is not
resistant to Ug99 it soon becomes apparent.
Thirty countries have sent germplasm for
screening to KARI and EIAR, and 225
000 lines of wheat have been screened since
2006.
Based on this screening process, 14
varieties of wheat that are resistant to Ug99
have been identified and are in testing with
various national governments and seed
programmes – and Ug99 resistant varieties
have now been released in Ethiopia. Under
an USAID (United States Agency for
International Development) project, Ug99
resistant seed has been distributed to six
countries. A total of 12 000 ha of resistant
varieties of wheat have been sown in Nepal,
Bangladesh, Afghanistan, Egypt, Ethiopia,
and Pakistan.
Scientists on the DRRW project want to
ensure that any new varieties released are not
based on single gene resistance. Ug99, like
any rust pathogen, has a great capability to
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