WEST LAFAYETTE, Ind. — Researchers from Purdue University
and the University of Nebraska-Lincoln have discovered a soybean gene whose
mutation affects plant stem growth, a finding that could lead to the development
of improved soybean cultivars for the northern U.S.
Purdue agronomy professor Jianxin Ma and collaborators
identified a gene known as Dt2 that causes semideterminacy in soybean plants.
Semideterminate soybean plants — midsize plants that
continue vegetative growth even after flowering — can produce as many or more
pods than current northern cultivars but do not grow as tall. Their reduced
height makes them more resistant to lodging, a bending or breaking of the main
“This gene could help us improve the yield potential and
adaptability of soybeans for specific growing areas,” Ma said. “We can now focus
on developing a variety of elite semideterminate soybean cultivars, which could
perform very well in high-yielding, irrigated environments such as Nebraska and
Soybean cultivars often are divided into two groups:
indeterminate, tall plants whose main stem continues to grow after flowering,
and determinate, shorter, bushier plants whose main stem halts growth when
blossoms begin to form.
Determinate soybean plants thrive in the longer growing
season of the south while indeterminate plants’ overlapping vegetative and
reproductive stages make them better suited to the north. But the height of
indeterminate cultivars renders them prone to lodging.
For northern soybean producers, semideterminate soybean
plants could represent a “Goldilocks” cultivar, a “just right” alternative
between the two.
Semideterminate soybeans are easy to manage, have similar or
better yields than indeterminate plants and can handle a short growing season,
Only one semideterminate soybean cultivar, NE3001, is common
in the U.S. Having pinpointed Dt2 will enable Ma and his researchers to use
natural plant breeding methods to develop a variety of semi-determinate
“The potential for soybean yield productivity in the U.S.
has not been fully explored, in part because of the lack of semideterminate
cultivars,” he said. “We’re now working on converting high-yielding
indeterminate cultivars to semideterminate types to test their yield
Ma — who had previously identified Dt1, the gene that causes
indeterminancy in soybeans — used an integrated genetic approach to isolate and
After identifying the gene, he inserted it into
indeterminate cultivars to confirm that it caused the plants to become
semideterminate. Dt2 suppresses the expression level of Dt1, causing soybean
plants to grow shorter.
Ma said this type of mutation appears to be unique to
soybeans as semideterminancy in other plants such as tomatoes and chickpeas is
caused by a different genetic mechanism.
Study co-author James Specht, a professor of agronomy and
horticulture at the University of Nebraska-Lincoln, said the identification of
Dt2 gives soybean breeders a powerful tool for breeding new cultivars.
“This provides breeders with a perfect genetic marker for
identifying semideterminancy in soybean seeds and seedlings,” he said.
The paper was published in The Plant Cell.
Other collaborators on the study are Thomas Clemente at the
University of Nebraska-Lincoln, Randall Nelson at the U.S. Department of
Agriculture and the University of Illinois and Lijuan Qiu at the Chinese Academy
of Agricultural Sciences.
Funding for the research was provided mainly by the United
Soybean Board and partially by the Partnership for Research and Education in
Plant Breeding and Genetics program of the USDA’s National Institute of Food and
Agriculture, Ag Alumni Seed, AgReliant Genetics, Beck’s Hybrids, ConAgra Foods,
Dow AgroSciences, Indiana Crop Improvement Association and Pioneer Hi-Bred