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Vol. 9, No. 3, October 2002
In This Issue
Project Aims to Maintain Disease
Resistance in Illinois Soybeans
One of the most troublesome plant diseases in many Illinois fields
is Phytophthora rot, which can infect and kill soybean plants anytime
from planting to harvest. This disease has been largely controlled
by planting soybean varieties with Rps resistance genes.
 But, recently the Rps genes have been losing some of their efficiency in several
states across the Midwest, creating the potential for renewed outbreaks of
the
disease in soybean fields.
To counter this problem, researchers from University of Illinois Extension
recently launched a project aimed at determining if the strains of Phytophthora
in Illinois
are developing the ability to kill soybean plants with the available Rps resistance
genes. Funding for this project has been provided by the Illinois Soybean Checkoff
Board.
“With help from seed company representatives and regional Extension educators,
we have collected and tested more than 200 soil samples from soybean fields with
a history of Phytophthora or similar seedling health problems,” says Dean
Malvick, plant pathologist with U of I Extension. “Those samples came from
more than 20 counties across the state.”
The researchers have obtained isolates of the disease-causing pathogen from
many of those samples and have tested them against commercial soybean varieties
with
the three types of Rps resistance genes.
“As expected, we found that many of the isolates from Illinois can defeat
the first of those resistance genes and that a smaller number can defeat the
second type,” Malvick says. “Unfortunately, we have found in our
preliminary work that a few aggressive isolates can defeat all three of the resistance
genes commonly found in commercial soybean varieties sold in the state. Although
these aggressive isolates exist in Illinois, we still do not know for sure how
much damage they may be causing.”
He notes, however, that the aggressive isolates do not appear to be widespread
in the state and that two of the three resistance genes are still effective in
most cases.
“We plan to continue our research to identify the various races of Phytophthora
in Illinois,” Malvick says. “Those results will help with selection
of soybean varieties with appropriate types of resistance and will be of real
value for breeders developing soybean varieties with Phytophthora resistance
best suited for the state.”
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| Glenn Hartman, USDA plant pathologist at
the U of I, examines soybean plants fro any signs of the fungal
disease soybean rust. The recent discovery of this disease in
South America for the first time has led scientists to begin
a comprehensive research program aimed at meeting the potential
threat if it reaches the U.S. in the next few years. |
Although considerable research money has been spent to combat a
wide range of soybean diseases, there has not been any systematic
effort over the years to preserve and collect samples of the various
pathogens that cause those diseases. As researchers retire or move
on to other projects, there is a real danger of losing isolates of
the pathogens that could be used to help control major soybean diseases
ranging from cyst nematode to sudden death syndrome.
“Assembling an extensive and genetically diverse collection of
soybean pathogens in one location would provide an invaluable resource
for identifying new genes for resistance in soybeans and understanding
the genetics of the pathogens that cause major soybean diseases,” says
Glen Hartman, USDA plant pathologist in the Department of Crop Sciences
at the University of Illinois. “In recent years, it has become
abundantly clear that such a collection is essential if we are to protect
the long-term productivity of the soybean in the U.S.”
To meet this need, Hartman and other collaborators across the country
have recently
begun assembling just such a collection at the U of I’s National Soybean
Research Laboratory. The National Soybean Pathogen Center will focus on collecting,
maintaining, and studying a wide range of bacterial, fungal, nematode, and viral
pathogens.
Initial support for the project came from the United Soybean Board,
the American Seed Trade Association, and the USDA Agricultural Research
Service. Recent funding
includes a grant from the USDA-IFASF Program.
“The main function of the center is to provide soybean pathogens to researchers
who are working on host resistance as a means of reducing yield losses caused
by disease,” Hartman says. “The center also will widely disseminate
information about the accessions in the collection and present workshops so that
researchers can work more efficiently with the pathogens.”
The Center is committed to maintaining the soybean pathogens in a viable
and stable state, while maintaining all original properties. The collection
will
serve as a reference collection for researchers in both the public and private
sectors.
“We will describe and document the variations in the soybean pathogens
from our collection,” Hartman says. “All that information will be
made readily available to other interested researchers. We also will assist other
scientists in identifying soybean pathogens and studying variations among the
samples in the collection as they relate to understanding pathogen biology and
the interactions with the hosts.”
Hartman notes that the collection will include living pathogens, representing
the range of genetic diversity within bacteria, fungi, nematodes, and viruses
that are considered important for improving soybean germplasm. Other programs
at the center will focus on training in germplasm screening and developing research
strategies for better understanding pathogen diversity.
“An accession number will be allocated to each incoming strain,” he
says. “Those that are further purified or selected will be assigned a new
accession number. A top priority will be to maintain the identity and viability
of the strains in the collection. Some pathogens will be maintained as frozen
stock, while others may be kept on living plant material.”
Accessions in the collection will be distributed through an online catalogue
without any charge. The collection will be housed at the National Soybean Research
Center (NSRC) on the U of I. campus. Other cooperators on the project will maintain
duplicate collections at several different locations.
He further points out that the location of the center at the NSRC provides ready
access to the USDA Soybean Germplasm Collection at the U of I.
“This unique collection contains more than 16,000 soybean accessions and
more than 1,000 accessions of the progenitor of the soybean,” Hartman says. “The
germplasm collection also has about 1,000 accessions of the wild perennial Glycine
species. We expect to have strong collaboration between the curator of the germplasm
collection and the scientists working with the pathogen collection, all of which
should prove of great benefit for soybean producers as new resistant soybean
varieties are developed and released.”
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The soybeans grown today in Illinois are descended from Chinese
varieties which were introduced into the United States between 1910
and 1930. Eight of those varieties contribute 75 percent of the genes
in the current varieties grown here.
And, according to Randy Nelson, curator of the USDA Soybean Germplasm
Collection at the University of Illinois, that narrow genetic base
could well limit future
progress to increase yields.
“In recent years, we have seen new diseases develop, such as sudden death
syndrome and white mold,” he says. “We also have found changes in
the pathogen populations of other diseases, such as Phytophthora rot and soybean
cyst nematode. Finding new genes for resistance to those diseases is critically
important for the health of soybean production in Illinois.”
He notes that the maximum genetic diversity for any trait is most
likely to occur in varieties from China because the soybean originated
there.
“During the time that the soybean became a major crop in Illinois, we had
no opportunity to exchange germplasm with China,” Nelson says. “In
1992, the Illinois Soybean Checkoff Board, the Illinois Agricultural Experiment
Station, and the USDA’s Agricultural Research Service finally established
a major germplasm exchange with the Chinese Ministry of Agriculture. Over the
following eight years, this collaboration increased the number of Chinese varieties
in our collection from 2,900 to nearly 6,100.”
Those new additions came from 27 different provinces in China, representing
all the soybean growing areas in the country. Prior to 1992, nearly 80 percent
of
the Chinese varieties in the collection came from only three provinces in northeast
China, and many provinces were not represented at all.
“Extensive research supported by the United Soybean Board has now demonstrated
the genetic uniqueness of those exotic Chinese varieties and the value of that
diversity,” Nelson says. “Improved resistance has been found for
nearly all the diseases that have been evaluated.”
For example, the highest known level of resistance to sudden death syndrome was
found among those varieties, as well as new sources of resistance to soybean
cyst nematode, white mold, brown stem rot, Phytophthora rot, and leaf-feeding
insects. Preliminary data also indicates that tolerance to drought may exist
in varieties from the area adjacent to the Gobi Desert.
“Ongoing genetic research is aimed at determining how those new genes can
be incorporated into the commercial varieties grown in Illinois and across the
country,” he says. “This exotic germplasm clearly has the potential
to improve the yield of the varieties that growers in our state will use in the
future.”
During the last six years, 14 experimental lines have been released for use
by
universities and private companies to develop improved varieties.
“By making comparisons at the DNA level, we can estimate how closely soybean
lines are related, even when we have no pedigree information,” Nelson says. “Based
on DNA similarities, the major ancestral lines of the U.S. varieties have been
placed into six genetic groups. The new exotic parents represent nine genetic
groups that are distinct from those contained in the major U.S. ancestral lines.”
Nelson points out that the most recent releases from this research were evaluated
at nine regional locations in 2001.
“One line derived from 25 percent exotic germplasm exceeded the yield of
the best commercial variety by nearly 12 percent and was the highest yielding
entry in the test,” he says. “Another experimental line derived solely
from the exotic Chinese lines equaled the yield of the best commercial variety
we tested. Those results indicate that the use of this exotic germplasm from
China has the potential to enhance disease resistance, increase yield, and improve
seed composition in the future.”
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The Council for Agricultural Science and Technology (CAST), a non-profit
consortium of scientists, released a comprehensive report on June
25, 2002 detailing the environmental safety and environmental benefits
of commercial biotechnology-derived crops, including soybeans.
"In the past, isolated studies regarding the environmental impact of biotechnology-derived
crops appeared to present conflicting results," says Teresa Gruber, the
executive vice president of CAST. "Teams of researchers assembled by CAST
have reviewed and analyzed the published studies in the context of current farming
practices, and the results clearly show that soil, air and water quality are
enhanced through the responsible use of current biotechnology-derived soybean,
corn and cotton crops."
Three independent teams of CAST researchers reviewed the available
scientific literature to compare the environmental impacts of biotechnology-derived
and traditional crops. The researchers are affiliated with Washington
State University, the University of Illinois, Clemson University, and
the National Center for Food and Agricultural Policy.
"The study was based on nine criteria including changes in pesticide use
patterns, impacts on beneficial insects, pest resistance, soil management, land
use efficiency, impacts on biodiversity and, of course, human exposure," says
Allan Felsot, Washington State University professor.
Specific findings for one of the most widely planted biotech-derived crops, herbicide-tolerant
soybeans, include the following:
- Soil Quality – No-till soybean acreage in the United
States has increased significantly since the introduction of herbicide-tolerant
soybeans.
No-till often results in less soil erosion, dust and pesticide runoff as well
as increased soil moisture retention.
- Water Quality – Use of biotechnology-derived soybeans
enable farmers to use a more benign herbicide that rapidly dissipates
in the soil and water.
- Air Quality – Greenhouse gas emissions from some
farm operations decreased by an estimated 88 percent as a result
of biotech soybeans planted
in a no-tillage system, which may help slow global warming.
- Biodiversity – The no-till practices commonly associated
with biotech soybeans provide a more favorable habitat for birds
and other wildlife. No-tillage
systems provide food and shelter for wildlife such as pheasants and ducks.
- Land Use Efficiency – Biotechnology-derived soybeans
may lead to increased yields through improved weed control and the
adoption of narrow-row
spacing.
The study found similar benefits for corn and cotton crops derived
through biotechnology. David Onstad from the Department of Natural
Resources and Environmental Sciences
at the U of I was one of two scientists who prepared the corn portion of the
report.
"We literally reviewed hundreds of scientific documents and we concluded
that biotechnology-derived corn has had a positive effect on the environment," Onstad
says.
Corn was a more complicated crop to review because there is Bt corn to control
insects, there are herbicide-resistant hydrids, and there are hybrids used for
animal feed as well as human food.
"Definitely, Bt corn has reduced pesticide use," Onsatd says "And
there was no evidence that non-target species are affected, in a negative way,
by biotechnology-derived hybrids. There was no evidence that these hybrids have
or will become off-site weeds either. Also, we expect that human exposure to
toxins has been reduced by the use of biotechnology-derived corn hybrids – both
toxins from chemical pesticides as well as naturally occurring toxins such as
aflatoxin.”
He points out that, although we have had positive environmental impacts
from biotechnology-derived soybeans, corn, and cotton, we need
to continue to monitor
present and future biotechnology-derived crops and conduct public-based research
to measure their efficacy.
Onstad further notes that the report contains ten recommendations about the
research needed to effectively monitor emerging biotech crops and technologies.
The report
was commissioned by the United Soybean Board, a non-profit organization representing
soybean farmers in United States.
Founded in 1972, CAST is a non-profit organization composed of scientific
societies and many individual, student, company, non-profit and
associate society members.
CAST assembles, interprets and communicates science-based information regionally,
nationally and internationally on food, fiber, agricultural, natural resource
and related societal and environmental issues to our stakeholders ‚ legislators,
regulators, policy makers, the media, the private sector and the public.
Read
the full report.
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Researchers Focus on Role of SCN
In Promoting Other Soybean Diseases
Although soybean cyst nematode (SCN) ranks as the top cause for
yield losses in Illinois soybean fields, recent research indicates
that it also plays a role in the development and spread of other
major diseases such as sudden death syndrome (SDS) and possibly brown
stem rot (BSR).
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| Terry Niblack, nematologist at the U of
I, collects samples of soybean cyst nematode for testing in the
laboratory. The recent acquisition of a computerized, high-speed
microscope for counting SCN eggs will drastically decrease the
time it takes to conduct tests on soybean varieties for resistance
to nematodes. |
“That’s bad news for Illinois farmers, considering that SCN occurs
in more than 80 percent of the soybean fields in the state,” says Terry
Niblack, nematologist in the Department of Crops Sciences at the University of
Illinois. “While SDS is fully capable of acting on its own, it now appears
that SCN hastens the development of symptoms from that disease and increases
the severity, leading to even greater yield losses.”
She notes that BSR also has become more widespread and severe in
Illinois than in the past. Once again, it appears likely that SCN
has played a role in those
changes.
Such an interaction between the fungus that causes BSR and SCN
was not considered likely until recently, when researchers at
Iowa State University found that SCN
can actually break resistance to BSR.
“In addition, we have found that BSR is now moving farther south in the
state, at the same time that SDS has been moving farther north,” Niblack
says. “Our old rules of thumb–that BSR is only a northern problem
and SDS is only a southern problem–have been showing signs of breaking
down.”
To meet the challenge, collaborative efforts are underway among
researchers from the Department of Crop Sciences and educators from
University
of Illinois Extension
to address the problems posed by those soybean disease interactions. Work in
the laboratory, greenhouse, and the field at a number of locations is focused
on studying the interactions between SCN and the fungi involved in SDS and BSR.
Major collaborators in the project on SDS are plant pathologists
Wayne Pedersen and Glen Hartman. Niblack is also working on BSR
with plant pathologists Dean
Malvick and Darin Eastburn. Soybean breeder Brian Diers is also contributing
resistant lines for the research project. Primary funding is provided by the
Illinois Soybean Checkoff Board.
“In this research, we will be looking at how SCN infection affects the
development of foliar symptoms from SDS and BSR,” Niblack says. “We
especially hope to find out exactly how and why this interaction occurs.”
Another part of the research will focus on determining whether the
interaction depends on the number of nematodes present, the genotype
of the fungus, the pedigree
of the soybean variety in a field, or other factors that have not yet been identified.
“We especially would like to find out how the disease interactions affect
management practices,” Niblack says. “Growers need to understand
whether it is more important to choose a variety with resistance to the nematode
or to the fungus that causes one of the other diseases. Even more problems would
arise if we determine that all three pathogens can interact in the same field.”
Based on the research up this point, Niblack recommends that growers
with SCN and SDS or BSR in the same field should take care of the
SCN problem first by
growing a resistant variety.
“This strategy is based on the simple fact that SCN is always present in
the field reducing yields, regardless of the environment,” she says. “At
the same time, SDS and BSR do not develop every year. As the work on this problem
continues, we should come up with new management practices that will help control
the problem of interaction between SCN and other soybean diseases.”
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 Recently
the University of Illinois had the pleasure of hosting Soy2002, the 9th Biennial
Conference of the Cellular and Molecular Biology of the Soybean. This was an
interesting event, where advances in basic science relating to the soybean
were shared. To provide a differing perspective, I had the good fortune to
provide a presentation on marketing and economic aspects relating to soybeans.
In preparing for that discussion, I had the chance to review data on the
progress that the soybean industry, including the research community, has achieved.
As
we all respond to our day to day pressures and challenges, we often lose sight
of some of these longer run accomplishments. Therefore, I thought that I would
share some of these insights at this time.
We are all aware of the importance of the soybean crop as an agricultural
commodity and the substantial expansion in production that occurred over the
second half
of the last century. By 2001, the world production of soybeans had increased
more than six-fold in the 40 years since 1961.
Intriguingly, the share of the world’s cropland devoted to soybeans
also jumped markedly in that period. The global acreage of alternative major
crops,
such as corn, wheat and rice, were relatively static, increasing only slightly
in this time period. Conversely the acreage devoted to soybeans expanded more
than three-fold from 1961 to today.
Of course, the fundamental reason for this expansion in production was that
the people of the world desired the food products that could be produced
from soybean
meal and oil. Consumption of these commodities increased more than seven-fold.
As the world experienced relatively favorable economic growth, the desire for
animal protein as a means to upgrade the quality of consumer diets also intensified.
For soybean meal, the seven-fold increase in poultry consumption and the more
than three-fold increase in swine production proved particularly important.
Even for those of us with close ties to the soybean industry, numbers about
production and consumption can become fairly drab. However, the ability to
provide enhanced
diet choices to an economically growing world population is a worthwhile goal.
Improving nutrition and contributing to human well-being have been important
accomplishments. As we look to the future, we see a continually growing world
population and hopefully we’ll see continued economic growth across the
globe. Both these forces imply the continued need for expanded sources of protein
and a key role for the soybean complex in responding to those needs.
Steve Sonka
NSRL Director and Soybean Industry Chair in
Agricultural Strategy
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The NSRL Bulletin is published three times a year by the National Soybean
Research Laboratory at the University of Illinois, 170 National Soybean Research
Center, 1101 W. Peabody Drive, Urbana, IL 61801; telephone (217) 244-1706;
e-mail nsrl@uiuc.edu; FAX (217) 244-1707.
Steven T. Sonka, director; Robert J. Wynstra, editor; Debra Levey Larson,
contributing editor, David Riecks,
photographer; Lynn Hawkinson Smith,
graphic designer.
Unless otherwise stated, articles may be reproduced
or quoted if credit is given to the NSRL Bulletin.
The National Soybean Research Laboratory at the University of Illinois is an
affirmative action and equal opportunity institution.
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