WSU’s On Solid Ground – Antibacterial Microbes, Legume Flour – Feb. 27, 2013

Natural Soil Antibiotics Offer Potential Alternative to Farm Chemicals

Linda Thomashow, a U.S. Department of Agriculture - Agricultural Research Service geneticist and adjunct professor in plant pathology at WSU.
Linda Thomashow

Research at WSU shows that several naturally-occurring antibiotics can control root disease and promote crop health, setting the stage for more economical and environmentally-sensitive options that farmers can use compared to the standard chemical fare.

“All you have to do is make your microbial community happy,” said Linda Thomashow, a USDA Agricultural Research Service geneticist and adjunct professor in plant pathology at WSU, during a recent presentation at the American Association for the Advancement of Science annual meeting in Boston. Thomashow said the door is open for scientists, farmers, and industry to develop commercial applications of root bacteria that can protect the rest of the plant.

Typically, science has concentrated on treating the above-ground parts of a plant, Thomashow said. “So much less is understood about the plant mechanics for defenses that are available underground.”

Certain bacteria produce antibiotics that protect crop plants.
Certain bacteria produce antibiotics that protect crop plants.

However, the tools of molecular biology have helped scientists understand the microbial and molecular workings of bacteria in the rhizosphere, the layer of soil next to roots, including how antibiotics there can suppress plant diseases. Thomashow calls these “a first line of defense.”

One particularly ominous-sounding disease, take-all, causes more than $1 billion per year in losses by rotting roots and depriving plants of water and nutrients. It’s often found in soils that are continuously replanted in wheat, whose money-making potential discourages farmers from planting alternative crops that might break disease cycles.

In some areas of eastern Washington, farms have seen several decades of continuous wheat. Those same soils have in turn seen high densities of the bacterium Pseudomonas fluorescens producing a compound called DAPG that can suppress the take-all fungus. Such beneficial bacteria create “suppressive soils” that help control soilborne pathogens with minimal use of commercial fungicides and other chemicals. It should be possible to get similar results with a commercially-available soil amendment if scientists, industry members, and farmers rise to the challenge and expense of bringing a living thing to market, said Thomashow. “If you balance that against the expense of developing a new chemical, it really doesn’t cost any more, and it’s a sustainable alternative to the use of chemicals.”

Learn more about take-all at http://bit.ly/15qn2CW. Learn more about how plant pathologists are discovering alternatives to chemical pest and disease control by visiting the WSU Department of Plant Pathology website at http://plantpath.wsu.edu/.

–Eric Sorensen

Adding Legume Flour to Wheat Bread Could Expand Markets

Roasting legumes before grinding for flour makes for better dough.
Roasting legumes before grinding for flour makes for better dough.

Legume flour can increase the amount of protein, fiber, minerals, the essential amino acid lysine, and disease-fighting phytochemicals in wheat bread. However, fortifying bread with legume flour can make the dough more difficult to process and result in low loaf volume. A recent article in Cereal Chemistry detailing a study led by Byung-Kee Baik, then of the WSU Department of Crop and Soil Sciences, revealed that the best way to counteract these problems is to roast the legumes before grinding into flour. By determining the best way to prepare legume flour for bread, the study could lead to more nutritious baked goods on supermarket shelves.

Baik suggests that flour made from roasted legumes, when incorporated into bread recipes, has more desirable characteristics compared to flour from raw, cooked, or fermented legumes. Roasted legume flour bread had higher loaf volume and a more appealing aroma than bread using cooked legume flour. In addition, bread dough made from roasted vs. raw or fermented legume flour was less sticky, and therefore easier to handle.

Beyond the health-promoting qualities that legumes can add to bread, they also help meet the goals of sustainable agriculture when used as rotation crops because they help to fix nitrogen, improve soil physical structure, and control pests and weeds. Baik’s study could therefore encourage more production of chickpeas, lentils, peas, and soybeans, as well as help growers find new markets for their harvest. To view the article, see http://bit.ly/TKNcwo.

To find out more about research in WSU’s Department of Crop and Soil Science, see http://bit.ly/wsucss.

-Bob Hoffmann

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