Unlocking the Key to Healthier Crispy Lettuce

Unlocking the Key to Healthier Crispy Lettuce
Professor David Still waters young lettuce plants in a Cal Poly Pomona greenhouse.
Eiji Hayashi, a postdoc, operates a robotic pipetting machine.
Research Assistant Ryan Mudry examines lettuce seeds under special green lighting in Still's lab.

Americans love their lettuce. Second only to potatoes, lettuce is consumed more than any other fresh vegetable in the country. The leafy green also produces a lot of green – nearly $1.7 billion a year in California alone, according to California Department of Food and Agriculture data.

Iceberg lettuce, which has little nutritional value, unfortunately remains the most consumed variety. The crispy lettuce goes well with hamburgers, another American favorite, but it basically does not do the body good.

It is a well-known fact that darker-leafed lettuce packs in more nutrition. Though the healthier varieties are being tossed in salads more often than in years past, they just dont deliver the crunch of iceberg and remain less desirable to the masses. A Cal Poly Pomona professor and a cadre of research assistants are developing a solution by blending the crispy qualities of iceberg with butter lettuce, a nutritional powerhouse in comparison.

“Even though consumption is increasing for healthier types of lettuce, it's plain to see people still like their iceberg lettuce,” says Professor David Still, who specializes in biotechnology. “Our laboratory is working on improving traits in lettuce so that it is easier to grow, lasts longer once harvested and will have better nutritional value for the consumer.”

For about seven years, this College of Agriculture's plant science professor has worked with lettuce in many ways. Still's research has ranged from developing improved seed germination under environmental stress, such as heat and salinity, to massive data gathering involved with genetic mapping and phenotypic characterization. Not to mention he actually grows his lettuce in a greenhouse on campus.

Still's Seed Lab, as some people refer to it, is a nondescript building that was once called the Honey House, where the old apiculture (beekeeping) unit was kept. It's likely most people who drive by the modest building in Cal Poly Pomona's Ag Valley have little idea that advanced DNA research is taking place inside.

“Some of what we do is fairly routine and labor-intensive, but a lot of it uses absolutely cutting-edge technology, like genomics and gene expression,” he says.  

Still wants to discover what traits in iceberg lettuce create the crunch and long shelf life and what qualities of butter lettuce produce vitamins A, C, E, K, folate and antioxidants. Using sophisticated equipment obtained through grants and partnerships spearheaded by Still, work is ongoing to this end.

In a greenhouse, there are rows and rows of lettuce that each come from hand-pollinated seed selections made from crosses of the lettuce types, which are germinated in the lab. Hundreds of genetic varieties have been grown to develop the ideal lettuce.

Still's research is largely made possible by matching funds from the Agricultural Research Initiative, which is the California State University's consortium of applied agricultural and environmental sciences research. The consortium includes other CSU campuses with agriculture colleges, including Cal Poly San Luis Obispo, Chico State and Fresno State.

In order to qualify for the ARI's matching funds, Still has received grants from public agencies including the U.S. Department of Agriculture, the National Science Foundation and the National Institutes of Health.  He has collaborative research projects with colleagues at UCLA, UC Davis and UC Berkeley among others. Industry partners have included ReadyPac, which sells prepackaged lettuce at grocery stores, and alumnus Don Huntley of Huntley-Moore Farms. Still has also partnered with seed companies such as Seminis Vegetable Seeds.

Through these partnerships and grants, Still has raised a substantial amount to fund his research over the years. This funding pays for all of his equipment and salaries for research assistants, some of whom have gone on to careers with biotechnology or biomedical firms.

“Doing research at a CSU is challenging because it is not a research-driven institution and does not receive state support for research. So we have to put a lot of time into acquiring these resources. Without partnerships like these, it would be impossible for me to conduct this level of research.”

Still is doing all he can to master seed germination and pack in more nutrition to crispy lettuce.

However, one question remains: Can he get Americans to stop using ranch dressing?