Agnet Dec. 2/03 -- II
Consumers
Association of Canada to release results of genetically modified food labelling
poll
First
"Notice of Submission" as part of a biotechnology pilot project
UK
field-scale evaluations answer wrong questions
Transformation
by the floral dip method
Tampering
with nature or tinkering with the truth?
Triticale
gets the best of both worlds - Wheat and rye
Map-based
isolation of the leaf rust disease resistance gene Lr10 from the hexaploid wheat
(Triticum aestivum L.) genome
how to subscribe
Consumers
Association of Canada to release results of genetically modified food labelling
poll
December 2, 2003
from a press release
OTTAWA - Media representatives are advised that the President of the Consumers
Association of Canada, Mr. Bruce Cran, and the Vice President of Issues and
Policy, Ms. Peggy Kirkeby, will be releasing the results of the Association's
just completed national poll on Labelling of Genetically Modified Foods.
Event: Press Conference, Calgary, Alberta
Date: Wednesday, December 3rd, 2003
Time: 11 AM Calgary time
Location: Sheraton Suites Calgary Eau Claire, 255 Barclay Parade, Calgary
First
"Notice of Submission" as part of a biotechnology pilot project
December 1, 2003
Canadian Food Inspection Agency
http://www.inspection.gc.ca/english/corpaffr/newcom/2003/20031201e.shtml
OTTAWA - The Canadian Food Inspection Agency (CFIA) and Health Canada announce
the first "notice of submission" to be posted to the CFIA’s web site
as part of the biotechnology pilot project to make information public on the
Internet about biotechnology-derived crops, livestock feeds, and foods submitted
for regulatory review.
The submission, submitted by Dow AgroSciences Canada Inc., is the first actual
posting since the pilot project’s launch on October 21, 2003. Dow AgroSciences
Canada Inc. is seeking approval for environmental release and livestock feed and
food use for corn designated as Event TC6275, which has been genetically
engineered for insect resistance (see the submission at www.inspection.gc.ca/english/plaveg/bio/subs/subliste.shtml).
Also participating voluntarily in this pilot project are other member companies
of CropLife Canada, the trade association representing developers of
biotechnology-derived plant products for use in agriculture. Member companies
have volunteered to provide the information for Canadians in the form of a
"notice of submission" for posting on the CFIA Web site.
The goal of the pilot project is to increase transparency in the regulation of
novel crops, feed, and foods. The public can make comments on products being
assessed to either regulatory body (the CFIA or Health Canada) through the CFIA
Web site.
The CFIA and Health Canada post lists of all approved plants with novel traits,
novel feeds and foods derived from biotechnology on their respective Web sites (www.inspection.gc.ca
and www.hc-sc.gc.ca), along with their accompanying decision documents and
regulatory directives.
UK
field-scale evaluations answer wrong questions
December 2003
Nature Biotechnology Vol 21, No 12, pp 1429 - 1430
www.nature.com
Bruce Chassy, Catherine Carter, Martina McGloughlin, Alan McHughen, Wayne
Parrott, Christopher Preston, Richard Roush, Anthony Shelton & Steven H
Strauss
Via AgBioView at www.agbioworld.org
The authors write in this letter to the editor that on October 16, 2003 the UK
Royal Society published a special volume of Philosophical Transactions that
reported the results of extensive field-scale evaluations (FSEs) of
herbicide-tolerant GM crops in the UK 1. On the basis of extrapolations from
this information, certain media and various environmental groups are citing the
FSEs as proof that genetically modified (GM) crops are environmentally damaging
and bad for biodiversity.
The authors say that such a conclusion is not justified by the published
findings. In the introduction to the papers, the study authors forewarn us that
"the FSEs address one particular environmental risk of one particular trait
in one particular agro-ecosystem, and the results should not be extrapolated to
other socio-environmental systems." 2The studies show that for two
herbicide-resistant GM crops--oilseed rape (canola) and beet—fewer weeds and
fewer insects from species that live in or on weeds were observed. Highly
effective weed control practices such as those the study chose to use with these
GM crops lead to low numbers of weed seeds and insects. In turn, fewer insects
and decreased weed seed might reduce the numbers of birds that feed on these
insects and seeds. In a conclusion that seems dire for crops that in any given
year cover less than 15% of the farmed area in the United Kingdom 3, the media
announced that GM crops will hurt bird populations, and therefore are bad for
biodiversity and should not be planted ( e.g. , see ref. 4).
It is important to note that birds were never counted nor was biodiversity
measured in these studies. The media discussion assumes two important points:
first, that availability of weeds and weed-associated insects are the dominant
factors determining bird populations—which is clearly not proven; and second,
that biodiversity can be equated with insects and weeds in crop fields. The
studies in question measured numbers of a few kinds of organisms in a several
small, selected habitats. They tell little about how these individuals interact
as populations and communities in these habitats and they tell nothing about the
biodiversity of the larger surrounding ecosystem.
Furthermore, such conclusions ignore the fact that weed populations are a result
of the management strategy, not the GM status of a crop. For example, an organic
farmer who thoroughly hoes a field would be equally effective at destroying
potential bird feed and habitat. A farmer who uses conventional herbicides
effectively along with mechanical tillage might do likewise. Thus, if leaving
more weeds in the fields really were deemed an appropriate public policy for UK
farmers' fields, farmers would simply need be mandated to use less herbicide,
rather than having their right to use GM crops curtailed. Indeed, the studies
demonstrated that weeds and some insects were more common in oilseed rape crops,
GM or conventional, than in beet or maize crops. Therefore, a more effective
method of increasing the numbers of arable weeds and insects in crops would be
to legislate crop choice.
Although the study designers acknowledge that it is unlikely to be the case, the
FSEs assumed current crop management systems would not change with the advent of
herbicide-tolerant crops 3. In actual practice, during seven years of planting
GM crops in the United States, agricultural practices have changed in a manner
that can broadly be described as beneficial for the environment and
biodiversity. A rapid adoption of no-till practices has accompanied the adoption
of herbicide-resistant crops 5. A move toward no-till agriculture leads to
decreased energy inputs, lower soil erosion and soils that are much healthier
with respect to structure 6-8 , microbes 9, invertebrate species 10 and organic
matter content 5. As a consequence of these changes, concluded Fawcett and
Towery, "the habitat for birds and mammals improves" 5.
Crop management strategies also influence aspects of environmental impact beyond
numbers of weeds and insects in the field. For example, the FSE studies totally
ignore the effect of pesticide residues on and off the farm field. The impact
could easily be evaluated and compared--for example, by using Cornell
University's (New York, NY, USA) Environmental Impact Quotient ( http://www.nysipm.cornell.edu/publications/EIQ.html
).
To truly test the impact of the GM nature of crops for their effect on
biodiversity--rather than the effect of a cropping system--the UK trials could
have focused on comparison of a single crop with a carefully matched
conventional counterpart. For example, FSEs could have grown replicated,
randomized plots of sulfonylurea-tolerant GM oilseed rape and conventional
sulfonylurea tolerant-oilseed rape, with and without sulfonylurea treatment.
This matched crop design would have tested the inherent safety and impact of the
GM nature of the crop. In all likelihood, the studies would have found little
difference in biodiversity between the planting of GM and conventional
sulfonylurea-tolerant cultivars. They would have found the highest numbers of
putatively 'bird-beneficial' organisms in the untreated plots, regardless of
cultivar, and the least weed seeds and weed-associated insects in the treated
plots, again regardless of the GM nature of the cultivar. Put another way, these
studies were not even about GM crops!
The ultimate question that should be asked is which agricultural technologies
will maximize production while minimizing environmental impact in the broad
sense. Herbicide-tolerant technology--notice that we do not say GM, because we
do not believe that it makes a difference what process was used to develop the
herbicide tolerance--may be one of those rare technologies that improves both
yield and product quality while reducing the environmental footprint of
agriculture. Besides contributing to the efficiencies of current European farm
systems in small spaces, judicious use of herbicides on both conventional and GM
crops could go the next step of maximizing food production on existing farmland.
With the resulting increased food production, society could dedicate the land
thus conserved as natural reserves, where many species could truly flourish,
providing even greater biodiversity--after all, farmland has never been intended
to be a natural habitat for any form of life except crops and farmers.
The publication of the FSEs demonstrated, as the investigators themselves
foretold, that GM critics will seize any opportunity to continue their anti-GM
campaign. News coverage of the FSE results also confirms that certain parts of
the media may be more interested in sensationalism than in getting the story
right. On a scientific basis, the most damming result from the FSEs is that GM
crops can make it too easy to control weeds! Perhaps most disappointing to us as
food and agricultural scientists is that the FSEs have created an unwarranted
negative impression of GM technology while answering all the wrong questions.
References
The UK Royal Society. The Farm-Scale Evaluations of Spring-Sown Genetically
Modified Crops. Philosophical Transactions of the Royal Society of London.
Biological Sciences, Series B vol 358 , issue 1439 (The Royal Society, London,
2003).
Firbank, L.G. Phil. Trans. R. Soc. Lond. B 358 , 1777–1778 (2003).
Squire, G.R. et al .Phil. Trans. R. Soc. Lond B 358 , 1779–1799 (2003).
http://www.guardian.co.uk/gmdebate/Story/0,2763,1053917,00.html
Fawcett, R. & Towery, D. Conservation Tillage and Plant Biotechnology: How
New Technologies Can Improve the Environment by Reducing the Need to Plow
(Conservation Tillage Information Center, West Lafayette, Indiana, USA, 2002).
VandenBygaart, A.J., Protz, R. & Tomlin, A.D. Can. J. Soil Sci. 79 ,
149–160 (1999).
Bruce, R.R., Langdale, G.W., West, L.T. & Miller,W.P. Soil Sci. Soc. Am.
J. 59 , 654–660 (1995).
Lindstrom, M.J., Schumacher, T.E., Cogo, N.P. & Blecha, M.L. J. Soil Water
Conserv. 53 , 59–63 (1998).
Angers, D.A., Bissonnette, N., Legere, A. & Samson, N. Can J. Soil Sci. 73 ,
39–50 (1993).
House, G.J. & Parmelee, R.W. Soil Tillage Res. 5, 351–360 (1985).
Transformation
by the floral dip method
December 2003
ISB News Report
Tawanda Zidenga
http://www.isb.vt.edu/news/2003/news03.dec.html#dec0304
The production and commercialization of transgenic plants has brought about a
revolution in agriculture. Plants have been engineered to resist insect pests,
tolerate herbicides, and grow under stress, among other traits. The production
of such transgenic plants requires three important procedures. First, a DNA
delivery system is needed to transfer the gene of interest into the plant cells.
Secondly, a selection system is required for separating transformed from
non-transformed cells. Lastly, we need a reproducible regeneration protocol.
This last step is often the rate limiting step, requiring specialized facilities
and often resulting in tissue culture-induced variation (somaclonal variation).
Current studies in plant molecular biology are focusing on the development of
transformation methods that avoid the tissue culture phase. A wide range of
these in planta transformation procedures is being explored. Injecting plasmid
DNA or Agrobacterium into meristems or developing floral organs has led to the
recovery of transgenic plants in Arabidopsis. Seeds can also be imbibed in DNA
and grown to maturity. Selection systems can then be used to isolate transformed
plants in the second generation. Vacuum infiltration is another approach in
which plants at an early stage are uprooted and placed into a bell jar in a
solution of Agrobacterium. A vacuum is applied and then released, causing air
trapped within the plant to bubble off and be replaced with the Agrobacterium
solution. The length of time a plant will be exposed to the vacuum is critical.
After transfer to soil, the next generation of transformed plants is selected
using antibiotic selection systems.
A modification of the vacuum infiltration technique is the floral dip method,
which currently is the most reliable in vivo transformation method. This method
relies on infiltration and transformation of Arabidopsis inflorescence by
Agrobacterium in the presence of a surfactant. However, this method has been
applied successfully only in Arabidopsis and the legume Medicago truncatula.
There is no doubt that continued research could lead to the adoption of this
method in other crop species. The remaining limitations on the full potential of
in vivo transformation are the current procedures for selection, identification,
and genetic analysis of the transgenic seeds.
In a recent study published in the July 2003 issue of the journal Plant
Biotechnology, Stuitje and colleagues assessed the use of fluorescent protein
genes as visual selection markers to facilitate the identification and
processing of transgenic Arabidopsis seeds. Seed specific promoters of the napin
gene or cruciferin gene were used to drive the expression of DsRed (Red
fluorescent protein from Discosoma sp), EGFP (enhanced green fluorescent
protein), EYFP (enhanced yellow fluorescent protein) or ECFP (enhanced cyan
fluorescent protein) genes. These seed specific marker genes allowed rapid
identification, selection, and genetic analysis of Arabidopsis transformants.
The researchers used the napin gene (nap A) to express the four fluorescent
protein genes (named above). A pBAR 100 plasmid, containing a seed specific EGFP
construct, was used. Agrobacterium-mediated transformation of Arabidopsis with
the gene construct was achieved using the floral dip method. Ripe seeds were
harvested three weeks after dipping and examined by fluorescent microscopy. From
the examination it emerged that EGFP remains active, even after seed
desiccation, and that the Arabidopsis seed coat effectively does not obstruct
excitation or emission, allowing its use as a visual (fluorescence) marker. This
was unlike the seed coats of Brassica napus and Petunia hybrida, which
interfered with the fluorescence imaging of the embryo, therefore preventing
application of this technology.
Furthermore, no significant difference was observed in germination competence
between fluorescent seeds and non-fluorescent seeds from the same batch,
indicating that the visualization of transformation by fluorescence provides a
clear advantage compared to the use of current positive (antibiotic resistance)
selection procedures. Developing intact siliques were also examined by
fluorescence microscopy. The transformed seeds become visible about 1.5 to 2
weeks after the transformation, suggesting there is a narrow window of time in
Arabidopsis flower development in which transformation by Agrobacterium is
successful. Co-transformation and genetic segregation analysis was also carried
out. Here, the researchers replaced the EGFP gene with its spectral variants (ECFP
and EYFP) and the unrelated DsRed. Transformation frequencies of up to 25% were
observed at a high infection density, while distribution of the transformed
seeds was apparently random. However, segregation analysis of the fluorescence
in the seeds of self-fertilized primary transformants showed that the T-DNA
insert behaved as a single genetic insertion in about 50% of the transformants.
Few co-suppression effects were observed, which, when coupled with the high
frequency of linkage, renders this technology ideally suited for introducing
multiple genes of interest for metabolic pathway studies in Arabidopsis.
Additional advantages of using fluorescent proteins as markers compared to
conventional positive markers were also explored. The effect of changing oil
quality on seed development and germination was studied. A construct, pBAR 111,
providing seed specific expression of the Cuphea palustris fatB2 gene, was
introduced into Arabidopsis. The gene in the construct encodes a thioesterase
with an activity specific for 14:0/16:0 fatty acid-acyl carrier protein
substrates. About 70% of the fluorescent seeds obtained from this transformation
showed a shrunken phenotype caused by the presence of the fatB2 gene. The
shrunken seeds contained levels of myristic (14:0) and palmitic (16:0) acids
often exceeding 50% of the total fatty acid content. Since none of these
shrunken seeds germinated, it was inferred that high levels of myristic and
palmitic acid could interfere with seed viability. Using conventional positive
selection markers such as antibiotic resistance, these detrimental effects on
seed development would have remained unnoticed. Thus, as the researchers put it,
the advantage of using fluorescence markers over positive selection markers also
includes a rapid perception of the effect of T-DNA insertion on embryo
development or seed morphology.
This work improves the understanding of in planta transformation, while
providing a method of tagging and identifying transformed seeds that could have
potential applications in plant biotechnology. More research on other plants may
help to assess the usefulness of this technology in plant biotechnology. A
limitation is that it cannot be used in some seeds like Petunia hybrida and
Brassica napus where the seeds coats interfere with the fluorescence imaging of
the embryo.
References
1. Stuitje AR et al. (2003) Seed-expressed fluorescent proteins as versatile
tools for easy (co)transformation and high-throughput functional genomics in
Arabidopsis. Plant Biotechnology 1: (4)301-309.
2. Bent AF. (2000) Arabidopsis in planta transformation. Uses, mechanisms, and
prospects for transformation of other species. Plant Physiology 124: 1540-1547.
3. Bechtold N and Pelletier G. (1998) In planta Agrobacterium mediated
transformation of adult Arabidopsis thaliana plants by vacuum infiltration.
Methods Mol. Biol. 82: 259-266.
Tawanda Zidenga
Plant Biotechnology Center
Ohio State University
zidenga.1@osu.edu
Tampering
with nature or tinkering with the truth?
December 1, 2003
Letter sent to the Editor of Bangkok Post
C. S. Prakash
Via AgBioView at www.agbioworld.org
Dear Editor, I was dismayed to learn that anti-technology groups continue to
stand in the way of progress in Thailand by creating promoting misinformation
about the safety and benefits of biotech or GMO crops, as evidenced in the
recent opinion piece by Greenpeace published in your newspaper ("Tampering
with Nature" 28 November).
Scientific and regulatory authorities across Asia and all over the world have
endorsed the extensive and growing base of published scientific information that
upholds the safety and benefits of biotech crops and foods. Spreading false and
misleading information in an effort to polarize opinion is irresponsible and
does not serve the public good.
The reality is that crops developed through plant biotechnology are among the
most well-tested, well-characterized and well-regulated food and fiber products
ever developed. This is the overwhelming consensus of the international
scientific community, including the British Royal Society, the U. S. National
Academy of Sciences, the World Health Organization, the Food and Agriculture
Organization of the United Nations, the European Commission, the French Academy
of Medicine and the American Medical Association.
Your readers have a right to know that biotech crops and foods:
- have been thoroughly assessed for food, feed and environmental safety and
found to be wholesome, nutritious and as safe as conventional crops and foods by
scientific and regulatory authorities throughout the world (examples include
insect-tolerant corn and cotton and herbicide-tolerant soybean); and - have
economic and environmental benefits that are significant and have met the
expectations of small and large farmers in both industrialized and developing
countries.
A study conducted by the National Center for Food and Agricultural Policy in
Washington found that biotechnology-derived soybeans, corn, cotton, papaya,
squash and canola increased the U.S. food production by 4 billion pounds, saved
$1.2 billion in production costs and decreased the usage of pesticide by an
impressive 46 million pounds in the year 2001 alone. Biotech crops are now grown
on 58 million hectares in 16 countries, and more than three-quarters of the 5.5
million growers who benefited from these crops were resource-poor farmers in the
developing world. For instance, South African, Mexican and Chinese farmers have
been growing transgenic insect-resistant cotton for several years, and the
Indian government approved it for commercial cultivation in spring 2002. In
SEAsia, Filipino farmers are celebrating the first anniversary of approval for
growing transgenic pest-resistant maize.
Thus, Contrary to the pseudo-scientific claims recently cited, GM technology has
actually decreased the usage of pesticide by an impressive 46 million pounds in
the year 2001 alone.
Despite these facts, misguided activists from around the world continue to
travel to places like Thailand to promulgate fear based on unsubstantiated and
misleading information. The reality is that none of these groups has actually
provided any credible scientific evidence that would call into question the
safety of foods derived from biotech crops on the market or the demonstrated
benefits to the environment.
Happily there are signs recently that decision-makers and the public are
resisting the temptation to be distracted by the emotional rhetoric of
anti-technology groups, and instead focus on the real work that's needed in
order to take advantage of the benefits of agricultural technology.
For example, in the Philippines, where anti-technology activists staged a hunger
strike, yet failed in their attempt to force the government to back away from
their approval of Bt corn. President Arroyo and Agriculture Secretary Lorenzo
remained firm in their commitment to the science-based safety assessments that
followed several years of rigorous research and testing of biotechnology under
Filipino conditions. Now thousands of farmers are beginning to reap the benefits
in terms of greater yields and less pesticide applications, improving the
Philippines ability to domestically produce grain for its poultry industry.
Forty other countries around the world are already so convinced of the safety
and benefits of biotechnology that they have approved field testing, import or
commercial production of crops.
In spite of the claim from Greenpeace that negative impacts of GMO crops on the
environment and farmers are still being discovered, many scientific studies
definitively show that GM crops are no more likely than their non-GM
counterparts to become agricultural 'weeds', and are no more likely to affect
biodiversity than any other change in agriculture.
On only one point do I agree with the Greenpeace opinion: the safety and
benefits of agricultural biotechnology in the Thai environment and for Thai
farmers needs to be demonstrated. And the only way to do this is for the
government to allow, closely monitor and thoroughly evaluate limited field
trials in government stations under the current strict regulations. To suggest
that this technology can be properly assessed without seeing it on the ground in
Thailand is tampering with common sense.
In Thailand there are many scientific experts with direct experience in applying
science and technology to food agriculture. I urge you in the media and other
decision-makers to rely on their experience, as well as the wealth of
international data that is available, as Thailand moves forward on its own terms
toward agricultural modernization - beginning with field testing all the way
through the product development chain.
Listen to sound science - not opinion -- on agricultural technology.
on the ecological risks and economic impact of GMO crops is still being
collected, assessed and understood, and the long term health impact of GMOs
remains unknown, the ban on GMO field trials must be treated as a necessary
measure to protect the rights and interests of Thai farmers, consumers and the
environment.
Varoonvarn Svangsopakul is a genetic engineering campaigner with Greenpeace
Southeast Asia.
Triticale
gets the best of both worlds - Wheat and rye
November 26, 2003
From a press release
Via AgBioView at www.agbioworld.org
Triticale is a hardy and new winter cereal crop created in a laboratory
environment by crossing wheat with rye. After years of effort over a 30-year
period, plant breeders, in particular those at INRA (France's National Institute
for Agronomic Research), have succeeded in making this species very attractive
to farmers.
Indeed, Triticale is today producing yields equivalent to, or better than, those
for wheat. Annaig Bouguennec, INRA s researcher in charge of the triticale
programme, explains: "Triticale currently represents a good compromise
between the hardiness of rye and the yield potential and nutritional qualities
of wheat."
Triticale is derived from crossing two other cereals widely cultivated in
Europe: wheat and rye. Its name is a combination of the Latin names Triticum for
wheat and Secale for rye. It was developed by scientists and is one of the rare
artificial species produced by interspecies crossing, which today are the
subject large-scale development in agriculture.
However, it took great perseverance by researchers to obtain such results
(see box).
A century of research
Along a historical timeline, triticale is a very recent species, but its
development has nevertheless taken almost 100 years to complete. The first cross
of rye and wheat dates back to 1876, when Scottish botanist Alexander Stephen
Wilson succeeded, for the first time, in pollinating soft wheat plants with rye
pollen in his greenhouse. However, this biological curiosity had no interest for
growers at the time since the seeds resulting from the cross were sterile, and
therefore could not reproduce.
In 1891, German botanist Wilhelm Rimpau discovered by chance a natural cross of
wheat and rye whose offspring was partially fertile. In the period 1920-1930,
Russian and Swedish researchers again tried to obtain fertile triticale seeds,
but without success. The discovery of colchicine, in 1937, was decisive in the
process that led to the creation of triticale. This natural substance, extracted
from crocuses, makes it possible to double the number of chromosomes in plant
cells.
Applying colchicine treatment to a hybrid of rye and wheat enabled researchers
to artificially double the number of chromosomes in seeds, thus making them
fertile. This is when triticale really saw the light of day. The first work
started in Canada and Sweden, followed by various other European countries
(Spain, Germany, Poland and Hungary). Triticale, however, had a number of
disadvantages, including limited grain yield, tall plants susceptible to
lodging, difficulty in threshing, a susceptibility for grain sprouting, late
maturity, etc. These drawbacks were too significant so that farmers showed no
interest in the new plant. In spite of these difficulties, plant breeders
remained hopeful and continued their work, which eventually led to the first
acceptable results by the end of the 1970s. Although the first varieties of
triticale arose from crossing rye and soft wheat, later researchers also crossed
rye with hard wheat, which allowed them to broaden the basis for selection.
From Prakash:
If 'Triticale-like wheat' were to be produced today using biotechnology to
infuse cold hardiness genes from rye to wheat, it would be treated with disdain
in France and other EU countries. Yet, Triticale is a synthetic crop that does
not exist in nature, and was developed artificially many decades ago by forced
mating of wheat and rye, and employed a highly carcinogenic chemical -
colchicine.
One can use all the contrived fears on food safety and environment being hurled
at GM crops, and can quickly come up with simple reasons to ban Triticale.
Yet, Triticale, now grown over six million acres around the world, proves that
there was never any harm from this 'genetically modified' crop and only much
good that came out of this bold experiment.
If 40,000 genes from rye does no damage in wheat, how can a couple of genes in
GM wheat pose any risk?
See also
http://www.worldbank.org/html/cgiar/newsletter/april97/8tritic.html
Map-based
isolation of the leaf rust disease resistance gene Lr10 from the hexaploid wheat
(Triticum aestivum L.) genome
November 25, 2003
Proc. Natl. Acad. Sci. USA, 10.1073/pnas.2435133100
Catherine Feuillet, Silvia Travella, Nils Stein *, Laurence Albar , Aurélie
Nublat , and Beat Keller
Institute of Plant Biology, University of Zürich, Zollikerstrasse 107, CH-8008
Zürich, Switzerland
Edited by Robert Haselkorn, University of Chicago, Chicago, IL, and approved
October 7, 2003 (received for review August 4, 2003)
http://www.pnas.org/cgi/content/abstract/2435133100v1
More than 50 leaf rust resistance (Lr) genes against the fungal pathogen
Puccinia triticina have been identified in the wheat gene pool, and a large
number of them have been extensively used in breeding. Of the 50 Lr genes, all
are known only from their phenotype and/or map position except for Lr21, which
was cloned recently. For many years, the problems of molecular work in the large
(1.6 x 1010 bp), highly repetitive (80%), and hexaploid bread wheat (Triticum
aestivum L.) genome have hampered map-based cloning. Here, we report the
isolation of the Lr gene Lr10 from hexaploid wheat by using a combination of
subgenome map-based cloning and haplotype studies in the genus Triticum. Lr10 is
a single-copy gene on chromosome 1AS. It encodes a CC-NBS-LRR type of protein
with an N-terminal domain, which is under diversifying selection. When
overexpressed in transgenic wheat plants, Lr10 confers enhanced resistance to
leaf rust. Lr10 has similarities to RPM1 in Arabidopsis thaliana and to
resistance gene analogs in rice and barley, but is not closely related to other
wheat Lr genes based on Southern analysis. We conclude that map-based cloning of
genes of agronomic importance in hexaploid wheat is now feasible, opening
perspectives for molecular bread wheat improvement trough transgenic strategies
and diagnostic allele detection.
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For more information about the Agnet research program, please contact:
Dr. Douglas Powell
Associate Professor
dept. of plant agriculture
University of Guelph
Guelph, Ont.
N1G 2W1
tel: 519-824-4120 x54280
cell: 519-835-3015
fax: 519-763-8933
dpowell@uoguelph.ca
http://www.foodsafety.ksu.edu
The Food Safety Network's bilingual toll-free line for obtaining food safety
information: 1-866-50-FSNET (1-866-503-7638)
archived at "http://131.104.74.73:96/agnet-archives.htm