Norwich, United Kingdom
February 19, 2009
A new gene that provides
resistance to a fungal disease responsible for millions of
hectares of lost wheat yield has been discovered by scientists
from the US and Israel.
“This is the first step to achieving more durable resistance to
a devastating disease in wheat,” said Dr Cristobal Uauy,
co-author of the report, recently appointed to the
John Innes Centre in
Norwich.
Resistance to stripe rust has previously been achieved using
genes that are specific to single races of the disease.
Unfortunately, each of these genes has had limited durability in
the field because the pathogen has mutated to overcome them.
In the paper to be published in Science Express tomorrow, the
international team of scientists report finding a novel type of
gene in wild wheat that is absent in modern pasta and bread
wheat varieties.
“This gene makes wheat more resistant to all stripe rust fungus
races tested so far,” said Dr Uauy.
The gene confers resistance at relatively high temperatures, and
a focus of Dr Cristobal Uauy’s research at JIC will be to test
how effective it is in UK-adapted varieties.
Bread wheat provides about 20 per cent of the calories eaten by
humankind and is the UK’s biggest crop export.
Dr Uauy has recently been appointed at JIC. He will lead a
research collaboration with the National Institute of
Agricultural Botany (NIAB) designed to deliver practical
benefits to agriculture. Research results will be made available
to breeders, so they can be deployed into modern varieties for
farmers.
Dr Uauy will use the latest genomic techniques to find genes in
wheat that directly affect yield and nutritional content.
Yield is a complex trait influenced by many environmental and
genetic factors. It was thought that the genetic component
determining yield was made up of many different genes each
exerting a small influence, but recent work led by the John
Innes Centre has challenged this view. Several stretches of the
genome, known as quantitative trail loci (QTLs) have been
identified that exert large effects on yield, in different
environments. Dr Uauy will lead the effort to find the precise
genetic basis for their effect on yield.
The John Innes Centre is an institute of the BBSRC.
Full bibliographic information:
‘A novel kinase-START gene confers temperature-dependent
resistance to wheat stripe rust’
Science Express
http://www.sciencemag.org/sciencexpress/recent.dtl
Wheat gene
thwarts stripe rust disease
Source:
University of California, Davis
An international team of
researchers, led by a University of California, Davis, plant
scientist, has identified a gene that should protect
commercially important wheat varieties from stripe rust, a
disease that causes severe crop losses in the United States and
other wheat-growing regions.
The research findings have significant implications for
consumers around the world, who rely on wheat for about 20
percent of their calories. Findings of the study are reported in
the Feb. 19 issue of
Science Express, the online version of the journal Science.
"We anticipate that introduction of the Yr36 gene into wheat
varieties used for making pasta and bread will have broad impact
on improving resistance to the fungus that causes stripe rust,"
said Professor Jorge Dubcovsky, a wheat breeder and geneticist
at UC Davis.
Stripe rust, which affects millions of acres of wheat, is caused
by the Puccinia striiformis fungus. Virulent forms of the fungus
have appeared in the past decade, overcoming known
disease-resistance genes in wheat and causing large yield
losses.
The fungus and resulting stripe rust are spread by the wind and
are most damaging to crops grown in areas with mild winters and
wet falls and springs. The disease first appears as rows of
yellow-orange spore clusters on wheat leaves.
The newly identified Yr36 resistance gene was first discovered
in wild emmer wheat, a low-yielding wheat that grows wild in
Israel. The gene is absent from modern wheat varieties used for
making bread and pasta.
The researchers identified Yr36 using positional cloning, a
technique which enabled them to pinpoint the gene's location on
the chromosome and identify its DNA sequence and predicted
protein. Publication of the gene sequence will give breeders the
ability to use sequence-based DNA markers to incorporate Yr36
into new wheat varieties.
The gene, which has been transferred into a handful of
domesticated pasta and bread wheat varieties, provides only
partial resistance to stripe rust. However, when combined with
other partial resistance genes, such as the Yr18 gene, it
provides adequate levels of protection.
"Historically, broad-resistance genes have been more durable
than those that confer more complete resistance, but to a much
smaller subgroup of races of disease-causing pathogens,"
Dubcovsky said. "In addition, the Yr36 gene protects wheat
against all known strains of stripe rust, making it an effective
tool for wheat breeders and growers.
Dubcovsky noted that wheat plants carrying the Yr36 gene in
California field trials, initiated in 2003, continue to
demonstrate resistance to the many types of stripe rust found in
the state. The plants produce significant yield increases when
the disease is present.
This research was funded by the U.S. Department of Agriculture's
Cooperative State Research, Education and Extension Service, and
the U.S.-Israel Binational Agricultural Research and Development
Fund.
Other UC Davis researchers working on the study were Lynn
Epstein; Daolin Fu; Assaf Distelfeld; and Cristobal Uauy, now at
Norwich BioScience Institutes, England. Other members of the
research team were Hanan Sela of the University of Haifa,
Israel; Ann Blechl of the U.S. Department of Agriculture's
Agricultural Research Service in Albany, Calif; and Xianming
Chen of the USDA Agricultural Research Service at Washington
State University.
For 100 years, UC Davis has engaged in teaching, research and
public service that matter to California and transform the
world. Located close to the state capital, UC Davis has 31,000
students, an annual research budget that exceeds $500 million, a
comprehensive health system and 13 specialized research centers.
The university offers interdisciplinary graduate study and more
than 100 undergraduate majors in four colleges -- Agricultural
and Environmental Sciences, Biological Sciences, Engineering,
and Letters and Science -- and advanced degrees from five
professional schools: Education, Law, Management, Medicine, and
Veterinary Medicine. The UC Davis School of Medicine and UC
Davis Medical Center are located on the Sacramento campus near
downtown.
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