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"Genetic variation is limited in the
commercial soybean varieties now being grown in Illinois, with only
three ancestors providing more than 50 percent of all the genes,"
said Brian Diers, soybean breeder in the Department of Crop Sciences
at the U of I. "This has the potential to hold back continued
improvements in yield and may increase the vulnerability of the U.S.
soybean crop to diseases."
The primary source of new genetic
material available to researchers is the USDA Soybean Germplasm
Collection at the U of I., which contains nearly 17,000 soybean
introductions from around the world.
"Significant effort is under way to use
this diverse germplasm collection to identify accessions that have
novel genes that improve yield and are resistant to different
yield-reducing diseases," Diers said. "As part of an integrated,
statewide breeding program, we plan to move useful genes from the
plant introductions into elite varieties that can be released
directly to growers or can be utilized as parents in other breeding
programs."
Diers notes that this work is being
carried out in close collaboration with Randy Nelson, curator of the
USDA Soybean Germplasm Collection. Primary funding for the effort is
provided by the Illinois Soybean Checkoff Board.
According to Diers, several populations
of breeding lines have already been developed by crossing elite
lines or cultivars with plant introductions or lines recently
developed from plant introductions.
"These exotic parents have been shown
to be genetically diverse and are likely good sources of useful
genetic variability," Diers said. "Work is also under way to confirm
previously identified genes that increase yield. This effort will be
done by developing and testing new populations that have the
identified yield genes segregating in them."
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In addition, Nelson's program has
developed backcross lines that out-yield their commercial parents,
despite sharing more than 90 percent of their genes.
"These backcross line will be useful in
the search for genes controlling the fundamental processes of
yield," Diers said. "They also will be helpful in identifying
genetic diversity that can improve the yield of our current soybean
varieties."
The genetic mapping of yield genes will
continue by testing lines from the populations at multiple field
locations for yield and other agronomic traits and with genetic
markers in the laboratory. Once useful genes are mapped, they will
be bred into elite germplasm and released as varieties or germplasm
for future research.
"This effort has already resulted in
the release of a high-yielding germplasm line for further research,"
Diers said. "This new line has the highest two-year yield average
among the Maturity Group IV lines in the USDA Uniform Test. Because
of its lack of resistance to soybean cyst nematode, we released it
as a germplasm line instead of as a commercial variety."
Diers notes, however, that the
development of new soybean varieties can be a long process that is
especially well-suited to the type of research under way at public
universities.
"The
maintenance of long-term public breeding programs engaged in the
development of highly diverse genetic populations is vital to the
U.S. soybean industry," Diers said. "This represents the way to
ensure that we are prepared to respond to new disease problems as
they arise and to the evolving needs and changes of the soybean
marketplace."
[University
of Illinois news release]
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