Researchers Identify Gene with Resistance to Soybean Aphids
Rob Wynstra (217)333-9446, firstname.lastname@example.org,
Source: Glen Hartman (217)244-3258
Farmers across the Midwest could soon have high-yielding commercial
varieties with effective resistance to soybean aphids as the result
of a major breakthrough at the University of Illinois. After nearly
three years of effort, a team of researchers at the U of I has
identified a single-gene source of aphid resistance that can be
easily crossed into elite commercial varieties.
The lead scientists in this effort are Glen Hartman, plant pathologist
with the USDA's Agricultural Research Service at the U of I, Senior
Research Associate Curtis Hill, and soybean breeder Brian Diers
from the U of I's Department of Crops Sciences. Funding for this
research has been provided by the Illinois Soybean Checkoff Board.
"This gene has been tested in both the greenhouse and the
field and has consistently prevented colonization by soybean aphids,"
Hartman said. "Because it is a single dominant gene with
identified DNA markers, it can be readily introduced into susceptible
commercial soybean varieties by backcrossing using marker-assisted
The methods for breeding plants with the aphid-resistance gene
will be licensed for use in both public and private breeding programs.
"Growers could have resistant varieties fairly quickly, especially
if industry adopts this technology," Hartman said. "I
think three to four years would be a reasonable time frame for
that to happen."
The aphids were first discovered in large numbers in fields near
the end of the 2000 growing season. After careful scientific investigation,
they were identified as Aphis glycines, which had previously been
reported only in Asia, Australia, and some Pacific islands. By
2003, this pest had emerged as a major problem for growers throughout
the Midwest. "When the aphids infest a field, the most common
means of control is to spray the field with an insecticide that
can cost as much as 20 to 25 dollars per acre," Hartman said.
"In 2003 alone, more than one million acres were sprayed
in Illinois and more than three million acres in both Iowa and
Minnesota. Once resistant commercial varieties are available,
the savings to growers will be substantial."
As part of their initial screening process, the team evaluated
the various commercial soybean varieties that had been submitted
to the yield trials at U of I for resistance to the aphids. "After
screening more than 700 varieties, we found that all of them were
basically susceptible to this pest," Hartman said. "We
also determined that there had not been any reported resistance
from the germplasm screened in the part of the world where the
aphids originated, which is China."
In the next step, they began screening about 100 cultivars that
had been identified as the major genetic contributors to modern
soybean varieties. Those ancestral lines account for more than
90 percent of the genetic variation in our current soybeans. "Luckily
we found resistance in two different cultivars," Hill said."
One is called Jackson, which is an old southern cultivar. Another
was Dowling, which also is an old variety grown in the south."
As part of the experimental design, the resistant cultivars were
tested in a specially designed field cage with several commercial
varieties and were treated with an insecticide or left untreated.
"Even with a large number of aphids present, we found virtually
no difference in yield and agronomic traits whether these resistant
lines were treated with an insecticide or not," Hartman said.
"At the same time, the commercial varieties were severely
damaged when they were not treated with an insecticide, with many
of the plants actually dying."
The researchers followed that up with a series of laboratory
and fields studies that identified the single dominant gene that
carried resistance to the aphids. They also developed methods
for identifying and breeding resistant plants using marker-assisted
selection. "We were able to identify the specific region
of the chromosome where the gene is located using genetic markers,"
Diers said. "Our team also confirmed that the resistance
is conferred by a single major gene. We are now using that marker
information to breed the resistance gene into adapted soybean
varieties and testing whether there is any associated yield or
agronomic drag associated with the gene. We hope to have resistant
varieties available to farmers by 2008."
With assistance from the Office of Technology Management at the
U of I, they have also applied for a patent and will soon be licensing
this new technology to both university and industry breeders.
"The idea of licensing is to make it a fair playing field
for everyone," Hartman said. "Otherwise an individual
company could take this research and patent the gene for itself.
By licensing the technology to a large number of companies and
public breeders, we can ensure that the benefits will reach growers
across the Midwest as quickly and cheaply as possible." For
more information check the website: http://www.otm.uiuc.edu/techs/techdetail.asp?id=267
Pasture Grass Fights Wheat Fungus Danger to Plants, Animals,
Susan A. Steeves, (765) 496-7481, email@example.com
,Source: Herbert Ohm, (765) 494-8072, firstname.lastname@example.org
Resistance genes in the grass that replaced genes in wheat increased
protection against Fusarium head blight, or wheat scab, the scientists
said. In the December issue of the journal Theoretical
and Applied Genetics the researchers also report
that they located and mapped the small bits of DNA, or markers,
associated with the resistance gene in the grass, called tall
"In the past 10 or 15 years, the fungus Fusarium graminearum
has emerged as one of the diseases of primary concern in wheat,"
said Herb Ohm, Purdue agronomy professor. "This is because the
widespread practice of reduced tillage in fields provides a perfect
environment for growth of the fungus."
Reduced tillage, meaning the soil is not plowed for planting,
cuts farmers' costs and helps prevent erosion, he said. In the
eastern United States, the upper Midwest and other places where
large amounts of corn and wheat are both grown, Fusarium is a
major problem, especially when the weather is warm and humid or
rainy. Corn stalks left as natural mulch after harvest also foster
The fungus causes head blight that leads to major wheat crop
losses. In 1996, crop losses due to Fusarium totaled at least
$38 million just in Indiana, according to the U.S. Department
"The disease has occurred most years since the early 1990s,"
Ohm said. "Its increase in frequency and severity coincide with
reduced soil tillage, along with favorable weather – warm, humid
conditions – for several weeks prior to and during wheat flowering
in mid- to late-May." The fungus also produces a mycotoxin that
sickens animals and people. Pigs, cattle, horses, poultry and
people can develop vomiting, loss of appetite, diarrhea, staggering,
skin irritation and immunosuppression when they eat grain or hay
infected by Fusarium. The most severe cases can be fatal. Research
has found evidence that these toxins may be cancer-causing. People
usually ingest the fungus when they eat contaminated grains and
cereals. According to the United Nations' Food and Agriculture
Organization, people in developing countries face the greatest
risk from Fusarium mycotoxins.
"Fusarium production of mycotoxins is a more serious problem
than wheat production loss," Ohm said. "The toxin results in complete
loss because you can't use the grain to make food for people or
The fungus can infect most cereal grains, including corn, wheat,
barley and some oats. Replacement of the wheat gene was done with
conventional crossbreeding and selection and didn't involve any
genetic engineering. Because the two plants are closely related,
the wheat is not altered, except for the added protection against
The newly identified resistance gene in the wheat grass is on
a different chromosome in the genome than other known resistance
genes used in wheat. This will enable researchers to combine the
newly discovered effective resistance gene from wheatgrass with
other genes that protect wheat against Fusarium. This breeding
of a plant with more than one resistance gene is called gene pyramiding.
Now that Ohm and his team of researchers know they can combine
the tall wheatgrass resistance gene with other resistance genes,
they will try to produce a line of wheat with several genes resistant
to Fusarium. The seed will then be available through the U.S.
Department of Agriculture-Agricultural Research Service laboratory
in Aberdeen, Idaho, that is a seed repository for wheat lines
from around the world. The Ag Alumni Seed Improvement Association
and Purdue Agricultural Research Programs provided funding for
Varying Soil Conditions Can Impact Nutrient Levels
By Candace Pollock, (614) 292-3799, email@example.com,
Source: Maurice Watson,
(330) 263-3755, firstname.lastname@example.org,
News and Media Relations, College of Food, Agricultural, and Environmental
Sciences, The Ohio State University, Columbus: (614) 292-2011, Wooster:
(330) 263-3775, http://ohioline.osu.edu/news/
This growing season's topsy-turvy weather may have impacted more
than crop performance and subsequent yields. Maurice Watson, an
Ohio State University Extension soil specialist with the Ohio
Agricultural Research and Development Center (OARDC), said that
the wet spring followed by a summer drought may have also affected
soil nutrient concentrations.
As a result, growers should test their soil for nutrient availability
following harvest to determine whether or not fertilizer is required
before spring planting.
"Most growers test their fields to determine nutrient concentrations.
We recommend testing every three years, so that growers over time
get a feel for the natural variation of nutrient levels in the
soil," said Watson. "This year is just more of a concern because
of the extreme wet and dry conditions we encountered." Watson
said that varying soil conditions affect a plant's ability to
uptake nutrients effectively. Under extreme wet conditions, the
oxygen supply to the roots is limited, affecting the uptake of
nutrients, even though the nutrients are present in sufficient
concentrations. Under drought conditions, plants are unable to
take up nutrients because of the lack of water flow to the roots
and the lack of growth or slow growth of the plant.
"Because of this year's drought, it is possible not as much fertilizer
will be needed by next year's crop on a field that was sufficiently
fertilized this year. In addition, it is possible that not enough
fertilizer was applied this year because of the very wet spring,"
Watson said. "Despite either condition, a soil test will determine
whether or not nutrients are at their optimum levels."
Watson said growers should mainly test for phosphorus and potassium,
the two main elements that can impact a plant's performance if
they are in deficient levels.
"In a nutrient-deficient situation, the biochemical reactions
are not going to be what they should be under normal conditions.
You may get a reduction in protein formation, which is the main
building blocks of the plant," said Watson. "A plant will tend
to take some nutrient elements from the older leaf tissue and
put it toward the younger leaves to compensate, particularly in
the case of nitrogen or potassium deficiencies. As a result, you
don't get the normal development of the plant and yield is then
Plants may also run into a nutrient imbalance if nutrient levels
are too high in the soil. Nutrient levels are also impacted by
soil type (sandy soils have less of a reservoir for nutrients
than clay or silt loam soils), as well as the type of crop being
planted. For example, corn silage and alfalfa remove more potassium
from the soil than grain crops.
New Soybean Line Offers Strong Resistance to Nematodes
By Jim Core, United States Department of Agriculture
A new soybean line from the Agricultural Research Service and
the University of Missouri delivers a rare combination of resistance
to two leading nematode pests. The release is good news for consumers
of edible natto soybeans. The germplasm line, designated S99-3181,
was initially bred for resistance to both soybean cyst nematode
(SCN) and southern root-knot nematode by Grover Shannon, a soybean
breeder at the University of Missouri's Delta Research Center
in Portageville, Mo. Prakash R. Arelli, a geneticist at the ARS
Nematology Research Unit in Jackson, Tenn., identified S99-3181
for its resistance to SCN.
Natto soybeans get their name from a Japanese fermented soybean
dish most commonly eaten at breakfast on top of rice, but it is
also used in other dishes and during other meals. Very few soybean
lines, especially natto type, have this combination of broad nematode
resistance and high yield potential, according to Arelli. In fact,
during field trails, its yield was found to be equal to, or higher
than, yields of Hutcheson, a popular cultivar. Additionally, the
line also has shatter resistance, which means it will hold its
seed after maturing.
The new line has broad resistance to SCN, the most destructive
soybean pest in the United States, causing annual losses as high
as $438 million. The cyst nematodes attack the roots of developing
plants. Root-knot nematodes are the second most destructive soybean
pest in the southern United States.
The line is expected to be used as a parent in breeding programs
to develop new varieties that reduce soybean yield loss and reduce
the need for pesticides. But growers might want to plant S99-3181
seeds directly, according to Arelli. The new line is a cross between
S93-1344 and Camp. Arelli uses traditional breeding and marker-assisted
selection to find new resistant genes in soybeans.