An Interview with Plant Geneticist John Stommel

Megan Sullivan

Bonus Points Education: B.S., Biology; Ph.D., Plant Breeding and Plant Genetics On the web: USDA Agricultural Research Service (www.ars.usda.gov) Related careers: geneticist, agricultural engineer, nutritionist, food technologist, botanist, horticulturist, plant buyer

Gregor Mendel’s work with pea plants in the 1800s established theories of heredity and long-standing genetic principles. Scientists have come a long way in understanding the inheritance of traits at the molecular level, gene interaction, and environmental influences. As technology advances, so does the ability to better appreciate genetic diversity. Plant geneticists, such as John Stommel, use traditional research and biotechnology-based approaches to develop plants with improved quality, nutritive value, consumer appeal, disease resistance, stress tolerance, and productivity.

What does a plant geneticist do?

Most people are aware of the work that scientists around the world are doing to sequence the human genome and its impact on research in the medical community. Similar efforts are underway in major crop plants, enabling us to identify and better use the genes that account for diversity in plant communities.

At the U.S. Department of Agriculture’s Vegetable Laboratory, we conduct basic research to help us understand the genetic and physiological basis for a particular trait—such as nutritive value, culinary quality, or disease resistance—and use that knowledge in applied research to develop an improved cultivated plant (cultivar) that benefits farmers and consumers. Basic research may involve using classical genetics and molecular biology. In applied research, we use traditional plant breeding, genetics, and biotechnology-based approaches.

Describe current projects.

My research program focuses on genetic improvement—primarily in fruit quality and nutritive value—of the tomato, pepper, and eggplant. All three species have many wild relatives, which in turn have a variety of attributes such as fruit color, vitamin content, flavor components, and processing quality. The genetic diversity of the wild relatives presents opportunities not only to improve conventional forms of the species, but also to develop novel forms not available in the market.

For example, the red and orange colors in tomatoes are attributed to the presence of carotenoid pigments that include lycopene and beta-carotene (compounds with well-known health benefits). We explore wild tomato relatives and natural tomato mutants to identify genes that may enhance levels of these compounds in the cultivated tomato. Similarly, in pepper, we are looking at a different class of pigments with potential human health benefits. In eggplant, we are evaluating phenolic acids, which are potent antioxidants and thus beneficial in the diet.

Using classical genetics, we characterize the inheritance of these traits to better predict the behavior of the gene(s) that influence expression of the trait. Using molecular biology tools, we may identify genetic markers to track these genes in studies and to introduce the genes into adapted cultivars. Likewise, molecular genetic tools are used to characterize the expression of influential genes—that is whether genes are turned on or off in different plants, how the action of one gene may affect the action of others, and how genes from exotic plant sources may function in cultivars.

The work spans research in the laboratory, greenhouse, and field environment. The interdisciplinary nature of the research often requires collaboration with other scientists who are experts in specialized areas of plant physiology, plant pathology, postharvest biology, and human nutrition.

Advice for students?

Today’s plant geneticist requires a strong background in plant sciences, genetics, and molecular biology. A familiarity with the developing field of bioinformatics is helpful as well.
Colleges, universities, and state and federal labs commonly support internship programs for aspiring students interested in scientific careers. Internships provide valuable opportunities for high school students to assist with research projects and conduct projects of their own in a laboratory. For students, one-on-one training and interaction with scientists provides new and unique insights into the scientific process.

—By Megan Sullivan

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