Wheat Journal

January 31, 2009 11:30 AM

Winter Hardy Varieties

Pass the bread. Growers have an all-new hard white winter wheat cultivar to consider for planting next fall.

Anton is the product of 15 years of selective breeding and evaluation by scientists with the USDA–Agricultural Research Service's Grain, Forage and Bioenergy Research Unit and the University of Nebraska's Agricultural Experiment Station (NAES), both in Lincoln, Neb. The variety is suited for production in the Northern Plains region as a source of high-quality flour for bread, noodles and other baked goods.

Anton is a wheat cultivar with reduced levels of the enzyme polyphenol oxidase, which leads to biochemical reactions that cause browning. Noodles made from white wheat flour sustain fewer color and brightness changes. White wheat flour also has a milder flavor than red wheat flour for use in whole-grain breads.

Anton grows about 31" tall and is somewhat resistant to stem and leaf rust diseases. It's moderately susceptible to stripe rust and tolerates wheat soilborne mosaic virus. In 2007 trials conducted by NAES, Anton averaged 50 bu. per acre, compared with 54 bu. to 57 bu. per acre for Nebraska's top three winter wheats. University of Nebraska Foundation Seed Division is handling requests for seeds.

Viral Victory

Wheat streak mosaic virus has a weak spot. A tiny gene has been found hiding in all members of a major family of plant viruses. Without this gene, the virus is rendered harmless.
The work is a collaboration between the Department of Plant Sciences at Iowa State University and the lab of John Atkins of University College Cork, in Cork, Ireland. The discovery was made while crunching through the genome sequences of the largest and most devastating family of plant viruses, called potyviruses.

The research is critical to agriculture because 30% of all plant viruses are in the potyvirus family—including the potato virus Y, a new strain tormenting potato growers in Europe and North America. Soybean mosaic virus is another potyvirus. Major fruits, such as plums, and vegetables, such as lettuce and pepper, are often devastated by potyviruses.

Researchers are now working to figure out how the gene—called the pipo protein—is expressed from the viral genome and what it actually does during virus infection. Stay tuned…


Avoid Head Blight Headaches

Heads up: Wheat scab will pick on fields where corn was planted the previous year. Fusarium head blight—also known as scab—is caused by the same form of fungus that causes Gibberella stalk and ear rot of corn.

"With the increased number of corn acres, there's a chance for more wheat to be seeded into corn stubble,” says Carl Bradley, University of Illinois plant pathologist. "Last fall's wet weather and late harvest resulted in stalk and ear rot of corn that can survive in corn stubble. Wheat planted into that stubble is at higher risk of being affected by scab.”

Bradley adds that spring weather determines whether scab rears its ugly head. The greatest risk for scab occurs when weather conditions prior to flowering are conducive for repro-duction of the fungus and when weather conditions during the early stages of kernel development favor infection. Three or more days with frequent rainfall and moderate temperatures (65°F to 80°F) during kernel development typically increases the risk of head scab.

Many varieties of wheat are susceptible to head scab, but varieties do differ in resistance levels. University of Illinois wheat breeder Fred Kolb evaluates varieties each year in his scab nursery. Results from those trials are available at the University of Illinois Variety Testing program Web site (http://vt.cropsci.uiuc.edu/wheat.html).

Symptoms of scab on wheat appear as white heads or heads that are half-white and half-green. Scab can reduce both yield and quality of winter wheat. Infected wheat kernels are usually lightweight, shriveled and chalky in appearance. The fungus is also able to produce deoxynivalenol, or vomitoxin, which can contaminate the grain.

Bradley says the best Fusarium head blight management plan uses inte-grated strategies which include crop rotation, planting partially resistant (or tolerant) varieties and spraying a fungicide, if warranted.

The best defense is a calculated offense. The Fusarium Head Blight Risk Assessment Tool uses weather data to estimate the risk of scab development (visit www.wheatscab.psu.edu). "The models used to develop the risk assessment have been shown to have nearly 80% accuracy,” Bradley says.

The risk assessment tool was developed through research funded by the U.S. Wheat and Barley Scab Initiative, a federally funded program that assists plant pathologists and wheat breeders who work on scab.

Down With Diseases

Wheat diseases won't get away with a single thing if USDA–Agricultural Research Service (ARS) scientists in Pullman, Wash., have their way. They've found a method to detect "genetic fingerprints” of fungi.

Although still being explored for commercial use, the real-time quantitative polymerase chain reaction (PCR) assays set the stage for building a comprehensive risk-management database to help farmers decide the best way to defend against the fungi, based on how much is present in the soil, as well as prevailing weather conditions and other variables.

Patricia Okubara, Timothy Paulitz and Kurtis Schroeder of the USDA–ARS Root Disease and Biological Control Research Unit in Pullman developed the assays, which detect 10 Pythium and seven Rhizoctonia species in a mere day. Past methods required scientists to culture the fungi and conduct greenhouse trials—a process that involved weeks of discovery.

In the Pacific Northwest, fungal diseases of seedlings and roots in spring and winter wheat cost growers from $50 million to $70 million annually in yield losses. Okubara says that in Washington State, Rhizoctonia root rot is so severe that some wheat growers have abandoned the practice of direct-seeding, a practice that conserves water and topsoil.

Go Go Genome

A three-year $6.8 million grant from the National Science Foundation (NSF) has University of California, Davis (UC Davis), researchers working on a plant genome project that aims to speed up the development of improved wheat varieties. Improved grain quality and nutrition, higher yield, resistance to pests and diseases and tolerance to adverse climate conditions are goals for the project.

Led by geneticist Jan Dvorak of the UC Davis Department of Plant Sciences, the project received the largest award from the NSF Plant Genome Research Program in 2008. It seeks to construct a physical map of one of the three genomes making up the chromosome complement of wheat.

Dvorak says the task is far tougher than mapping the human genome because higher plants differ in size. "Each of the three wheat genomes, for example, is an order of magnitude larger than the genome of rice. We have never had the technology to physically map and sequence huge genomes such as those of wheat,” he says.

A physical map is a representation of the order of genes and other landmarks along a chromosome. To construct a physical map, genomic DNA is fragmented and the fragments are cloned and "fingerprinted.” Overlaps between fingerprints are used to identify neighboring DNA fragments and to arrange them into a contiguous sequence corresponding to the DNA sequence in the chromosome. Scientists can then determine the location of genes and other markers in these fragments and sequence them.

While it will take years and further studies before the full wheat genomic sequence will be available to the agricultural research community, NSF sees the project as a vital first step.

"The knowledge from this project will be helpful in all aspects of wheat breeding and biotechnology because it will accelerate the discovery and isolation of economically important genes,” Dvorak says. "The project will also advance understanding of the evolution and the global organization of large plant genomes.”

The NSF began making annual grants through its Plant Genome Research Program in 1998.

Biotech Wheat Vote

In January, wheat growers around the country had a chance to weigh in on whether the industry should deploy biotech trait commercialization in wheat. The results of the survey will be released in the form of a petition at Commodity Classic 2009, Feb. 26 to 28 in Grapevine, Texas.

"The petition is designed to document the depth and breadth of support for biotechnology among wheat producers,” explains Daren Coppock, CEO of the National Association of Wheat Growers (NAWG). "Anecdotally, we're convinced the support is there—this petition will either confirm or confront that belief.”

Wheat acreage in the U.S. has been on a steady decline for the past 30 years as other crops with access to biotech traits have competed for producer interest and delivered greater
returns, says William Wilson, North Dakota State University ag economist.

Companies interested in commercializing a biotech trait for wheat are facing multimillion-dollar investments to develop, deregulate and launch the trait. NAWG hopes the petition will convince them to undertake this commitment. For more information, visit www.wheatworld.org.


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