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Reza Sohrabi

Reza Sohrabi in Latham plant lab

Reza Sohrabi, a Ph.D. student in biological sciences, in Latham Hall plant lab.

Stealing the playbook: a Ph.D. student researches the complex plant defense system

 

When a plant is attacked by a pathogen or pest, it doesn't just sit meekly by. The plant defense system launches into a red alert mode, producing chemicals to ward off the attacker directly, and even indirectly, by producing chemicals that attract natural predators to the given pest. An example of this is when a grape plant prduces antifungal plant phenolics in response to attack by gray mould fungi, or when tobacco and chili pepper plants produce capcidol in response to attack from an oomycete water-mold.

Reza Sohrabi, a Ph.D. student in biological sciences, has been enamored with the complexity of the plant defense system for many years. He is working with Dorothea Tholl, associate professor of biological sciences and an affiliated faculty member with the Fralin Life Science Institute, to examine the role of terpenoids-- organic compounds produced by plants in response to pest and pathogen attack.

"We want to find out how terpenoids are made, and can defend plants," Sohrabi said.

Terpenoids, also called terpenes, are the main ingredients in the essential oils of many types of plants and flowers, and have a strong fragrance. A class of terpenes, known as 'homoterpenes,' are produced and emitted in response to pest attack by a variety of plants, including important crop species such as corn, lima bean, and cotton. Homoterpenes are thought to be involved in the attraction of herbivore's natural enemies, and thereby defend plants indirectly against attacking pests.

While it was long thought that homoterpenes are produced in leaves only, the Tholl research team discovered that they are also produced in roots, Sohrabi said. Furthermore, using the Arabidopsis plant model, the research team found that the compounds are produced by different pathways above ground (leaves) and below ground (roots). A manuscript summarizing this work is under preparation for publication.

"In the below ground system, the same compound is made from a novel pathway and provides a potential direct defensive function against pathogens," Sohrabi said. "Using quantitative trait loci (QTL) analysis, we were able to narrow down candidate genes loci for terpene production. We also used publicly available microarray data sets, in combination with QTL analysis, to make a short list of gene candidates involved in terpene production."

Sohrabi became hooked on plants as an undergraduate student at the University of Tehran, when working on a project that involved screening transgenic sugar beets resistant to viral infections. During his Ph.D. research at Virginia Tech, he became interested in understanding molecular mechanisms of plant defense against microbes via defensive chemicals.

"This line of research is important because studying the mechanisms of how plants defend themselves against pathogens provides a platform for developing cultivars that are more resistant to pathogens," he said.

 

Q&A: Meet Reza

Hometown: Gachsaran, Iran
Major: Biological Sciences
Fralin Advisor: Dr. Dorothea Tholl
Other Degrees: BSc and MSc in Cell and Molecular Biology, University of Tehran
 

What attracted you to your particular field of science?

As a biologist I have been always fascinated with the beauty of plants and enjoyed spending time outdoors. Besides that, plants are major sources of foods for humans and livestock which make them very important for human life. The fact that the current amount of food production in the world probably would not be sufficient to feed the rising world population in the next 50-60 years worried me. So I believe that we have to start now to develop sustainable agricultural resources to save the world in the next 50 years or so. One approach for establishing sustainable agricultural resources is to enhance crop yield by developing crop varieties that are more resistant to existing pest and pathogens. Therefore we would have less crop loss due to pest and pathogen damage. That is why I want to become a plant biologist.

What are your ultimate career goals?

I am interested in developing a research program to study plant interactions with organismal communities in the rhizosphere (the thin layer of soil surrounding the roots) and to understand how these interactions effect plant growth and development. My ultimate career goals are to work as a researcher in academia and to use my knowledge and skills to solve important problems in plant science and agriculture toward enhancing food security.

Which quality of the following do you feel is the most important for a scientist to possess—open-mindedness, precision, time management skills, optimism, cynicism, integrity, a good sense of humor? Why?

I would choose open-mindedness. The reason is that in science major discoveries are made by those people who were open to new ideas and applied new approaches and technologies to tackle scientific problems. Scientists should not be confined by current understanding of scientific phenomena and embrace hypotheses that are novel and even radical to facilitate new discoveries.

Be a geek: what’s your favorite piece of equipment to use in the lab?  Why?

The Gas chromatography and Mass spectrometry (GC-MS) instrument is my favorite instrument. Because it is a very powerful instrument for detecting very small amounts of chemicals.

Which type of science, other than what you study, interests you most?

Immunology, because I am really amazed how our immune system recognizes self from non-self and how the vast varieties of antibodies are made against foreign agents for mediating the immune responses.

A quote or story that’s recently inspired you?

Yes, a quote by Thomas Jefferson: “I'm a great believer in luck and I find the harder I work, the more I have of it.”

Favorite hobby outside of school?

Playing volleyball with my friends.