SDSU undergraduate earns plant science fellowship for soybean research

Farm Forum

BROOKINGS, S.D. — Investigating the role that micro-RNA 160 plays in the development of soybean nodules sounds like graduate research, but South Dakota State University undergraduate Spencer Schreier has undertaken the task through a fellowship from the American Society of Plant Biologists.

The Belle Fourche native is the first SDSU student to receive this award.

“I didn’t realize how accessible research was here for an undergraduate student,” said Schreier, who had already completed his honors project before getting the fellowship. The biology major will graduate in 2015.

The fellowship provides Schreier a $4,000 stipend, $700 for lab supplies, and travel and registration to present his work at the annual society meeting in Portland, Ore., in July.

Breeding soybeans that capture more nitrogen can reduce the amount of fertilizer needed and lead to more sustainable farming practices, explained Schreier. “Nodules are very important in relieving our reliance on nitrogen fertilizers.”

He began his research work last summer under the supervision of plant scientist and assistant professor Senthil Subramanian, whose specialty is plant genomics.

The soybean genome sequence was completed in 2010 and scientists have since been unraveling the genes. Subramanian’s research focuses on the soybean root structure and nodule formation.

Importance of micro-RNA

Micro-RNAs regulate the expression of specific genes, explained Schreier, who works in Subramanian’s lab where graduate students are identifying those that play a role in the development of nodules, which house bacteria that fix nitrogen in the soybean plant.

Subramanian compared micro-RNAs to the brakes of a car.

“Micro-RNA regulates the levels of the target gene’s activity,” Subramanian explained. This means keeping its activity under a particular threshold, confining the activity to specific cell types and properly timing the increase and decrease of the activity levels. These interactions affect the plant’s nodule development and its subsequent ability to fix nitrogen.

Micro-RNA 160 is one of a multitude of micro-RNAs that affect plant development, Schreier noted. His research examines “at what stage in nodule development this micro-RNA is being expressed and what hormone is being accumulated at each stage.” The hormone auxin prevents nodule formation, while another hormone cytokinin triggers growth.

Schreier used a fluorescent protein sensor that can be regulated by micro-RNA 160 to see which root and nodule cell types are affected using an optical imaging microscope, he explained. “When the green fluorescent protein is gone, the micro-RNA is being expressed.”

Spencer’s work complements a U.S. Department of Agriculture project aimed at identifying the precise function of micro-RNA 160 in root nodule development. Postdoctoral researchers Marie Turner and Narasimha Rao Nizampatnam first activated the micro-RNA 160 and then removed it and compared the results.

Schreier’s results agreed with those of the postdoctoral researchers, Subramanian noted. “Micro-RNA 160 levels must be low in developing nodules, but high in mature nitrogen-fixing nodules.”

It’s all a matter of timing, Schreier added, “making the correct proteins at the correct time.”

The work has fueled his desire to study molecular biology in graduate school. “I didn’t anticipate the work being as enjoyable as it is. I learned how great it can be to work on a team.”