SCIENTISTS DISCOVER HOW NEMATODES ATTACK

Plant pathologists Thomas Baum (right) and Tarek Hewezi, developed a new approach to studying microRNAs, powerful regulators of gene activity, to better understand how nematodes change gene activities in plants.

By Ed Adcock

Soybean cyst nematodes have been found in fields in every Iowa county. The plant-parasitic microscopic roundworms cause an estimated loss of $1 billion dollars annually to U.S. soybean producers.

The pests get their name from the shell-like cysts, each containing hundreds of eggs, that persist in the soil until a susceptible plant is within reach.

Iowa State plant pathologists have made a breakthrough in the understanding of how cyst nematodes attack plants at the genetic level, providing the possibility of giving soybeans a way to fend off the pest.

Rosetta Green, an agricultural biotechnology company, licensed the technology last summer with the goal of developing nematode-resistant plants. The company’s agreement with the Iowa State University Research Foundation is based on research deciphering how cyst nematodes infect plants.

The research is led by plant pathologists Thomas Baum, professor and chair of plant pathology and microbiology, and Tarek Hewezi, an associate scientist.

Cyst nematodes are damaging pathogens of plants worldwide. The pests feed on plant fluids by attaching to the host plant’s roots.

Scientists previously discovered that nematodes hijack plant development by injecting cells with chemical signals that cause hundreds of cells to fuse into a feeding site.

Baum and Hewezi sought to understand how the nematode changes the plant’s gene activities for the purpose of turning it into a food source. The researchers’ new approach was studying microRNAs, which are powerful regulators of gene activity.

“These worms learned to communicate with these plants’ cells in a very subtle way,” Baum says.

The researchers used the plant Arabidopsis as the model because it has a relatively small genome, and studied how sugar beet cyst nematodes attacked it. They discovered a relationship one microRNA had with two genes that are associated with growth regulation.

Hewezi and Baum used molecular biology techniques to generate experimental plants in which the microRNA levels are elevated in roots attacked by cyst nematodes and they found these plants were not as susceptible to the nematode. And when they adapted the target genes to be unaffected by the microRNA, they found these plants were less susceptible as well.

“Our results indicate that the microRNA, together with its target genes, has a real function in the interaction and it’s required to a certain degree for the pest to attach to plant roots,” Baum says.

The Iowa Soybean Association funded research that led to the discovery, and the National Science Foundation recently funded a three-year study for $607,875 to continue work with Arabidopsis micro-RNAs during cyst nematode parasitism.

FINDING A FUTURE IN ECOLOGICAL RESTORATION

Andrew Paxson grew up enjoying the outdoors in the in Fox River Valley area northwest of Chicago. As president of the student Soil Water and Conservation Club he builds ground water flow models.

By Barbara McBreen

Andrew Paxson spent his summer biking, canoeing, mussel hunting, weeding and educating others about the importance of ecological preservation. It was an intern- ship that fit him perfectly.

“We covered ecology, history, philosophy, economics, botany and geology all in nine weeks,” Paxson says. “The internship helped me understand that I’d like to pursue a career in ecological restoration.”

Paxson, a senior in environmental science, spent last summer as an intern with the McHenry County Conservation District at Glacial Park. It’s an area north-west of Chicago and north of Algonquin, Ill. The 3,500-acre park is located one hour north of where Paxson grew up hiking and enjoying water sports.

“I like to challenge interns with basic questions,” says Tom Simpson, field station ecologist with the McHenry County Conser- vation District. “This summer we had many involved discussions about how and why we do conservation. Andrew was always engaged in the discussion, which helped everyone else participate.”

This summer brought hot, dry weather to most of the Midwest, which made it challenging to work outside Paxson says. At times he was worried about starting fires with vehicles used in the park. As streambeds began to dry up, he also participated in a mussel rescue and survey.

“We were on our hands and knees in the river trying to find these mussels in the mud, it was like finding gold,” Paxson says.

When he returned to Iowa State this fall, he found the drought also dried up his water-sampling job. For the past three years Paxson has taken water and sediment samples from Squaw Creek to measure E. coli. The water sampling not only provided a job, but a basis for his research.

“The data is interesting because we have samples from flood years and from last spring when the creek began drying up,” Paxson says.

Michelle Soupir, professor of agricultural and biosystems engineering, says Paxson’s help with data collection will provide the basis for stream modeling. The project not only measured E. coli in the water, but also in the streambed.

“He went out weekly and collected water and sediment samples,” Soupir says. “We found that bacteria concentrations in the bottom sediment was higher than the overlying waters.”

Paxon’s research focused on plotting
E. coli concentrations in watersheds using geographic information systems technology. The results will be included in a modeling project used to predict E. coli concentrations in streams. He presented his research in poster sessions through the Science With Practice program and at the Research at the Capitol event in Des Moines. Both programs give undergraduate students research experience with mentors and faculty.

Paxson served as president of the Soil and Water Conservation Club Student Chapter from 2009 to 2012, which builds water flow models for educational groups. He also was a member of the Skunk River Navy, a student group that cleans trash out of the river. He also gained practical experience serving on Iowa State University’s Storm water committee.

BRINGING SCIENCE TO LIFE IN THE CLASSROOM

 Nancy Boury, a senior lecturer in animal science, incorporates real- life scenarios to engage students in microbiology, biology and genetics.

By Barbara McBreen

Microbes rule the world. That’s a fact that Nancy Boury shares with students in her Microbial World class.

“There are more microbes in one person’s gut than there are people who have ever lived on earth,” says Boury, a senior lecturer in animal science (’97 PhD molecular, cellular and developmental biology).

To make introductory micro- biology, biology and genetics interesting, Boury incorporates real-life scenarios into her classes. In one class she asked students to bring evidence both for and against the idea that microbes can influence weight gain. She also asked students to analyze the source of the research they used as evidence.

“I want students to think and not just memorize,” Boury says. “Information literacy is important because students need to understand the source of information they use to make decisions.”

Making students comfortable in the classroom is a priority for Boury. She does that by trying to memorize everyone’s first name, which isn’t an easy task when you have more than 250 students. She also asks them to submit a question on the first day of class. Every fall she spends two weeks responding to each question.

“It would be easier to teach these classes if I didn’t care, but I care,” Boury says. “I went to a small, private, liberal arts school and I try to take the advantages of that setting and bring them to the class.”

If you sit in on one of her classes it’s obvious the students enjoy her and are involved in the learning process.  Her goal is to encourage students to reach their full potential, provide an active learning experience and bring science to life.

Boury advises first and second year microbiology students and is the Microbiology Learning Community coordinator. One former student and advisee, Janae Hohbein (’09 microbi- ology) who is attending the Des Moines University College of Osteopathic Medicine, says she still uses the study techniques she learned from Boury.

“I can honestly say that without her mentoring, I would not be flourishing in medical school,” Hohbein says. “Many professors can boast about the grades their students get and the things their students achieve, but only a few can boast about who their students become as people.”

Ed Braun, professor of plant pathology and microbiology, team-teaches the microbiology class with Boury. Braun focuses on the plant aspect and Boury’s focus is more on the animal and human health areas. He says Boury has a great rapport with students.

“It’s fantastic to watch the level of inter- action she has with the class,” Braun says. “She’s serious, but leavens it with humor.”

That humor is important to Boury. She asks students to bring in cartoons or other microbial humor she can share with her classes and says student compete to be featured.

VIROLOGIST VIES TO ADVANCE YIELDS AND HUMAN HEALTH

W. Allen Miller, professor of plant pathology and microbiology, has become one of the world’s leading authorities in research of viruses.

By Ann Marie Edwards

W. Allen Miller is using his understanding of viruses to aid both plant and human health.

In one such project Miller, professor
of plant pathology and microbiology, is working to introduce a gene into soybeans harmless to mammals, but toxic to aphids that feed on soybean plants. He collabo- rates with entomology professor Bryony Bonning (see page 6) on the project.

Miller wasn’t always interested in the survival of soybeans.

“I became fascinated by molecular biology when I was a college student. When I went to graduate school I decided I wanted to help feed the world rather than do medical research. I would study agricultural research or biotechnology even though I had no background in plants or farming,” says Miller.

He started to focus on viruses while earning his Ph.D. degree at the University of Wisconsin. Miller is now recognized
as one of the world’s leading authorities on mechanisms of barley yellow dwarf virus molecular biology.

Since joining the ISU faculty in 1988, his research has made important contri- butions to several disciplines including RNA structure and function of viruses (referring to the type of nucleic acid they use to store genetic information).

By publishing and sharing his findings, Miller has made the molecular biology world more aware of plant viruses as fascinating model systems. His work has been funded from many sources including the National Institutes of Health.

Today, Miller and his colleagues study molecular biology of plant RNA viruses from several perspectives including RNA virus replication from plants to humans.

“We employ plant viruses as easy-to-use model systems to provide basic understanding of how viruses express genes and replicate,” Miller says. “This knowledge may be relevant to major human viruses such as hepatitis A and C viruses, West Nile and more.”

While running his research lab Miller works to create a stimulating environment for students and postdocs.

“The lab is almost like a family,” Miller says. “Some of my proudest achievements beyond scientific discovery are the number of scientists who I have trained. Many of my students have gone on to very successful careers as scientists.”

Miller’s former student Elizabeth Pettit Kneller (PhD ’05 plant pathology), agrees.

“Dr. Miller is really enthusiastic about science and instills an excitement about virology in his students. He gives students opportunities to be involved with grant applications and presenting at conferences,” says Pettit, a scientist at KeraNetics, an advanced biomaterials company in Winston-Salem, N.C.

Miller recently began a faculty profes- sional development assignment at the Institute for Plant Molecular Biology in France. While on the 10-month assign- ment with the French governmental research organization, he will continue to study translation mechanisms, but with a different set of plant viruses than he studies at Iowa State. The new lineup includes viruses important to sugarbeet and potato production. He will use this new experience to build his research program at Iowa State.