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Defensive soybean genes aim at these diseases and maladies

pathogens build up quickly in a tight rotation like corn and soybeans. That’s
led seed companies like Pioneer Hi-Bred to incorporate a wide array of
defensive traits.

bean will be in the market seven to eight years,” says Paul Stephens, Pioneer
senior research director for soybean product development. “You have to have a
product that will cover different

in different years. One year, it might be white mold, the next year, it might
be a different disease.”

Sudden Death Syndrome

2010 in Iowa, that “different disease” was Sudden Death Syndrome (SDS).

is a difficult disease for which to develop resistant varieties, since multiple
genes are involved. Diseases like Brown Stem Rot, in which a single gene
conferred resistance, was not as difficult to breed into a single line, he

have grown in our ability to prevent SDS,” says Stephens. He says 80% of
Pioneer soybean varieties for 2011 have a ranking of 6 (1 on this scale is
highly susceptible, 9 is highly resistant). In states like Illinois, a Pioneer
sales representative will not typically position a product in a field unless it
has a 6 SDS rating or above, he says. 

Phytophthora root rot

that resist phytophthora root rot are getting tired.

“The old phytophthora genes not as good as
they used to be,” says Stephens. The corn-soybean monoculture and pathogen race
shifting are breaking down the resistance, says Stephens. To boost resistance, Pioneer
breeders are improving resistance by grouping phytophthora-resistant genes
together to develop multiple-gene resistance.

White mold

Researchers are also researching new ways for
soybeans to resist white mold. “We are developing better tolerance that slows
the rate of the (white mold) fungus going on the stem,” says Stephens. “We also
want to improve canopy architecture. We want to create a more open canopy.”

varieties with a narrow canopy create an environment conducive for white mold
under high humidity. A wider canopy would help deter white mold by circulating
more air within the canopy.

Soybean cyst nematode

is developing a transgenic solution to protect against all soybean cyst
nematode (SCN) races.

big part of our system is so much corn and soybeans, corn and soybeans,” says
Stephens. “In these areas, we see a buildup of the soybean cyst nematode

good news regarding SCN is there is no longer yield drag in resistant varieties
as there was in the 1990s.

our new enhanced breeding systems, we got away from the (yield drag) baggage
associated with those (SCN-resistant) genes,” says Stephens.

Soybean aphids

soybean aphid-resistant varieties are coming from Pioneer for use in the 2013
growing season. One drawback with single-gene resistance is soybean aphids can
quickly overcome the resistance. Thus, Pioneer continues to search for new and
effective aphid-resistance genes

Optimum GAT for soybeans

plans to bring Optimum GAT soybeans to market as soon as regulatory approval
occurs. If this occurs, Pioneer plans to market it for 2013. Optimum GAT is a
new herbicide-tolerant trait that confers tolerance to glyphosate and ALS

the corn side, Pioneer is continuing to evaluate Optimum GAT and is targeting
commercialization for mid-decade. 

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