www.checkbiotech.org ; www.raupp.info ; www.czu.cz

Worrying about whether or not the forecast calls for rain may be a thing of
the past when the next generation of drought-tolerant corn hits the market,
September 2006 by Wayne Wenzel.

We?re not talking about breeding better plants with deeper roots or traits
that prevent insect feeding. Now, genetic engineering and high-speed gene
shuffling let breeders and engineers pinpoint the plant genes that affect
crop yield under moisture stress.

After a decades-long marathon, today?s big three seed firms?Monsanto
Company, Pioneer Hi-Bred International Inc. and Syngenta?are in a sprint for
the finish line. Finally, it appears technology has advanced far enough for
one or all of these companies to soon make a serious run at high-yielding,
drought-tolerant hybrids.

For farmers, the timing could be perfect. As energy prices skyrocket and
drought patterns shift, it can cost up to $100 to irrigate an acre of corn.
Some aquifers are depleting at an alarming rate, and competition for limited
water supplies is fierce. Meanwhile, corn production is under increasing
demands to fuel ethanol plants, feed livestock and satisfy exports. With
these forces at work, marginal acres, including those more prone to drought
stress, could soon be growing corn.

While the market opportunity and technology for better drought hybrids
exist, a cautious optimism pervades seed companies? claims about drought
programs. Their caution, however, is tempered by the need to compete.

Monsanto/DeKalb

Perhaps sensing the finish line, Monsanto recently broke from the pack,
making bold statements about its drought research. The company?s CEO, Hugh
Grant, announced this past spring that Monsanto will start commercial sales
of drought-tolerant corn after the turn of the decade.

Grant also said the company has completed 53 large-scale field trials during
the past two years and is now identifying the highest-yielding seeds. While
Monsanto now pulls genetics from 36 germplasm pools around the world, much
of Monsanto?s drought success traces back to its acquisition of DeKalb. One
hybrid in particular, DKC63-78, has shown success against drought in
Illinois, Indiana and Iowa. Its drought tolerance comes from a specific
Mexican inbred line.

Along with specific drought-tolerant germplasm, Monsanto also acquired
DeKalb?s drought discovery and development work in Mystic, Conn. DeKalb?s
long-time molecular research and breeding hub continues to be the center of
Monsanto?s drought research.

John Headrick, chief of development for drought-tolerant corn at Monsanto,
is optimistic that his company will be the first to come to market with
yield-competitive hybrids engineered specifically to tolerate drought. But,
he refuses to reveal too many details about the exact methods Monsanto is
using to attain its goal. Concern about protecting intellectual property is
high.

There are clues, however. Monsanto has released promotional photos and video
of drought-tolerant hybrids not rolling their leaves under drought stress,
so it would seem one key is the corn?s ability to maintain leaf surface area
under drought conditions.

Despite the promotional teaser, Headrick is quick to point out that reduced
leaf rolling is only one possible route to drought resistance. ?Reducing
plant water loss, or evapotranspiration, is one thing we look at in drought
tolerance,? he says, ?but we consider the whole plant from the roots up. It?
s not absolutely necessary that leaves don?t roll at all; in fact, leaf
rolling itself is a defense mechanism. The leaves on a drought-tolerant
plant may still roll some and help preserve moisture. We?re looking at a
number of leads and characterizing them in early stage field tests.?

Headrick also reveals that while Monsanto?s most recent tests in corn have
been a success, earlier research that led to key pathways in drought
tolerance was done in a plant called Arabidopsis. This small relative of the
mustard family has been called the lab rat of plant genetics because it
grows quickly and is relatively easy to work with genetically.

A quick search of the scientific literature shows that Michael Thomashow of
Michigan State University was one of the first researchers to use
Arabidopsis to discover a genetic mechanism that protects cell walls and
membranes during periods of drought and cold. Some rights to his research
were licensed to a company called Mendel Biotechnology, which began
promoting the technology as Weathergard.

Today, Monsanto prominently stands out among companies that have research
exchange agreements with Mendel Biotechnology. Monsanto and Mendel recently
renewed their agreement.

So, is Weathergard the key to Monsanto?s program? Headrick will only say
that the company is looking at many sources for drought tolerance, including
simple microbes, native corn traits and other plant sources.

DuPont/Pioneer

Jeff Schussler, a research scientist with Pioneer?s drought program,
remembers an old joke from his days as a scientist with USDA. ?If you want
it to rain, establish a drought study.?

While Schussler admits the joke isn?t that funny, he says it demonstrates a
frustration shared by corn drought researchers and farmers. In the Corn
Belt, drought is common but unpredictable as to where it will strike.

Based on 50 years of data collected by USDA and Pioneer, Schussler estimates
that in any given year, one-third of U.S. corn acres experience
yield-reducing drought stress.

?Weeds and insects used to be the primary yield robbers, but now drought is
No. 1,? Schussler says.

Over a decade ago, Pioneer built a greenhouse covering some of the corn
research plots near the company?s Johnston, Iowa, research campus. With a
roof and no sides, the ?drought house? still keeps special drought-tolerant
corn candidates dry in case of rain, testing the corn?s ability to produce a
crop with less water.

Though still in use for early stage projects, Schussler says the drought
house is mostly a relic of Pioneer?s old drought program. Today?s program is
international in scope and includes research stations in arid areas.

Pioneer now dedicates two 200-acre research stations and thousands of test
plots around the world entirely to drought research. One station in
Woodland, Calif., receives less than 1" of rainfall during the growing
season. Corn plots receive their water only through high-precision
irrigation. A second station in a similarly arid region south of Santiago,
Chile, allows for year-round drought research.

?Our drought candidates come from a three-pronged approach that includes
conventional breeding, molecular breeding and transgenic programs that might
move novel genes into corn,? Schussler says. ?Sometimes our own conventional
breeders and genetic engineers find themselves in a race to find the same
solution.?

Thus far, Pioneer?s breeders have had some success. There have been bumps
along the road, though. Pioneer?s early attempts to breed in or insert
drought-resistant genes from sorghum into corn, for example, proved more
difficult than expected. ?We?ve learned that drought tolerance, like yield,
is more likely the result of many genes interacting in the plant. This
favors conventional corn breeding over single novel gene insertion like with
Bt corn,? Schussler says.

But, technology helps a lot. Pioneer has identified promising drought traits
in some inbreds by using marker-assisted breeding and high-speed gene
shuffling technology from Verdia, a company purchased by Pioneer?s parent
company, DuPont.

It also helps that Verdia?s labs in Redwood City, Calif., are just down the
road from Pioneer?s drought station in Woodland. ?The key for us has been to
have all of the breeders, scientists and agronomists working together,
looking at many more hybrids and inbred lines under drought,? Schussler
says. ?We?ve substantially accelerated this effort over the last decade.?

He points out that Pioneer has recently discovered several hybrids with
exceptional drought tolerance and high yield potential. Some of those headed
to market share a parent inbred from the recently successful 108- to 110-day
Pioneer 33D11. The hybrid has shown an ability to throttle back its water
use and maintain green leaves without rolling as much. It also tends to put
out silks more robustly than other hybrids, silking a couple of days earlier
than pollen shed.

?With continued research and breeding, we believe the old idea of having to
select a racehorse hybrid for yield or a workhorse hybrid for drought
response will be a thing of the past,? Schussler predicts.

Syngenta/Greenleaf Genetics

With its acquisitions of Garst and Golden Harvest and an agreement to share
traits and germplasm with Pioneer through its Greenleaf Genetics subsidiary,
Syngenta has an immense pool of corn genetics to sift through. Somewhere in
those millions of DNA combinations lies the secrets to high-yielding,
drought-tolerant corn.

Making sense of data and identifying promising targets require an army of
scientists assisted by high-tech-enabled shotgun screening techniques. The
process uses the latest robotic lab equipment and brute force computing to
winnow down the DNA and its multitude of variations in corn.

Getting to the drought-tolerance finish line, though, also requires vision
and a willingness to act on a hunch.

That?s where Syngenta?s drought project leader Scott Valentine thinks his
company may have an advantage. With a Ph.D. specializing in chemical gene
switches that turn genes on and off, Valentine focuses on finding the switch
that tells corn to redirect energy and nutrients away from the kernel and
into the leaves and stalks during drought stress.

?Corn?s drought response during flowering is key to most of the yield losses
we see from drought, so it makes sense to focus our efforts there,?
Valentine says. ?We want hybrids that can set full ears during drought, but
to do that, we have to understand why corn redirects its energy away from
kernels.?

Valentine suspects that the key lies in a gene-switching mechanism that goes
back to corn?s ancestral relative, teosinte. Rather than one or two big ears
like today?s corn hybrids, teosinte continually produces many small nodal
ears through its growth cycle. Shutting down seed production during a
drought would not jeopardize teosinte?s reproduction because more ears could
grow later. Modern corn only gets one shot at producing seed.

?Today, Syngenta has some corn candidates that appear to keep the yield
effect of modern breeding and also stop the kernel abortion throwback trait
of teosinte,? Valentine says. ?In multi-year field trials, our lead event
has shown consistent yield improvement over control hybrids. The yield
improvement is far better than incremental?more than just 1% or 2%.?

Valentine won?t speculate on when commercial hybrids with Syngenta drought
traits will be available. ?Looking at native trait and biotech trait options
for drought takes time. It?s harder than adding a new Bt protein, for
example, because Bt is a foreign protein that does not interact with plant
function. But, plant interaction is what controlling drought response is
about. When we get it, I think drought resistance will be a broad-acreage
trait that almost everyone will want.?
[www.agweb.com]

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