Improving the Nutritional Content of Lettuce: The Second Most Consumed Vegetable in the US

Diets rich in fruits and vegetables are linked to a reduced risk of many cancers, cardiovascular, mental and other chronic diseases.  Epidemiological studies have failed to identify individual fruits, vegetables, or specific phytochemical components that are responsible for lowering these risk factors.   Consequently, current recommendations support the intake of whole fruits and vegetables, especially those that are nutritionally dense.   Because an individual’s dietary habits are difficult to change, a logical strategy is to improve the nutritional content of fruits and vegetables that are already consumed in high amounts.   Lettuce is consumed in large amounts across much of North America, Europe and parts of Asia.   Depending on lettuce type, the amounts of certain, but not all, essential nutrients, vitamins and potentially healthful phytochemicals compare favorably to other vegetables typically consumed at much lower levels.   The ultimate goal of our research is to release genetic lines with greatly increased content and a better balance of specific essential nutrients, vitamins and phytochemicals.  To that end we have employed next-generation sequencing, population-level transcriptional profiling, and multiple years of field testing to identify genetic and environmental factors which regulate these nutritional components.   Our research indicates large variation in the lettuce gene pool and a significant environmental component in modulating nutritional components.  The overall nutritional profile of lettuce can be improved through traditional breeding but much bigger gains are possible using transgenic approaches.