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Research Highlights

Research Highlights
Kachroo continues nitrogen research

By Amie Buckman, Kentucky Soybean Intern

Many farmers would say it would be a wish come true to plant a soybean seed that would take maximum advan­tage of nutrients found in the soil – nutrients they don’t have to add. University of Kentucky scientist Aardra Kachroo is leading the way in research for the development of the ultimate nutrient-utilizing soybean plant.

When her previous research indicated that certain strains of bacteria could be beneficial to soybeans, Kachroo expanded the scope of her project and began to work more extensively with those strains to improve soybean productivity. The long-term goal of Kachroo’s latest project is to increase the efficiency of nodu­lation and develop soybean lines with improved nitrogen fixation and increased yields.

Each year, most farmers find themselves with higher fertilizer expenses for grain crops. The bulk of this fertilizer is comprised of nitrogen, one of the six macronutrients needed by the soybean plant. 

Nitrogen is an essential component of the basic building blocks of life. In order to be utilized by living organisms, including plants, nitrogen gas in the Earth’s atmosphere must be fixed into usable forms. The process of biological nitrogen fixation is catalyzed by the Rhizobium species of bacteria. Many plants of the legume family, of which soybeans are a part, form symbiotic relationships with such bacteria. This relationship involves the formation of the root nodule, a specialized plant organ containing the ideal environment for Rhizobacteria to convert nitrogen into ammonia. In turn, the ammonia is released into the soil to be used by the plant.

Often times, farmers will rotate their crops so that plants that do not have nitrogen-fixing nodules can use the remainder of the nitrogen not used by the previous crop.

Through a genetic analysis of naturally occurring variations of soybean rhizobacteria, several dominant genes that restrict nodulation by specific rhizobial strains have been identified. Kachroo’s research has focused on silencing the genes that cause restriction to improve nodulation, which in turn results in an increase of ni-trogen produced by the soybean plant. Once the restricting genes are silenced, the plants with the target gene sequence will be grown in vermiculite and introduced to the appropriate amount of rhizobacterial strain to measure nodulation and nitrogen fixation.

Kachroo’s goal is to begin field trials in 2014. “If everything goes as planned, I hope to have seedlings planted next summer,” she said. Currently her research is conducted in her lab and green-houses located at the University of Kentucky.

Aardra Kachroo began working with the University of Kentucky in 2006. Recognizing that soybeans are a very important crop for the state of Kentucky, she hopes that her research is beneficial to soy-bean farmers. The Kentucky Soy-bean Promotion Board has fund-ed several of Kachroo’s research projects over the past few years. “These days research funds are really low. We could not do this without the support of the Board. It’s been a huge help,” she said.

To find research related to this Research Highlight, please visit the National Soybean Checkoff Research Database.