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Submitted to: Journal of the American Society for Horticultural Science
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 4/6/2005 Publication Date: 11/1/2005 Citation: Mou, B. 2005. Genetic Variation of Beta-carotene and Lutein Contents in Lettuce. Journal of American Society for Horticultural Science. 130(6):870-876. Interpretive Summary: There is increasing medical evidence for the health benefits derived from dietary intake of carotenoid antioxidants, such as ß-carotene and lutein. Enhancing the nutritional levels of vegetables would improve the nutrient intake without requiring an increase in consumption. A breeding program to improve the nutritional quality of lettuce must start with an assessment of the existing genetic variation. We analyzed the carotenoid content of 52 lettuce varieties grown in the field in summer and fall of 2003. Wild lettuce accessions had higher carotenoid content than cultivated lettuces. Among major types of lettuces, carotenoid content followed the order of: green leaf or romaine > red leaf > butterhead > crisphead. Crisphead lettuce accumulated more lutein than ß-carotene, while other lettuce types had more ß-carotene than lutein. Carotenoid content was higher in summer than in the fall. The results suggest that enhancement of carotenoid levels in lettuce through breeding is feasible. Technical Abstract: There is increasing medical evidence for the health benefits derived from dietary intake of carotenoid antioxidants, such as ß-carotene and lutein. Enhancing the nutritional levels of vegetables would improve the nutrient intake without requiring an increase in consumption. A breeding program to improve the nutritional quality of lettuce (Lactuca sativa L.) must start with an assessment of the existing genetic variation. To assess the genetic variability in carotenoid content, fifty-two lettuce genotypes including crisphead, leaf, romaine, butterhead, wild species, primitive, Latin, and stem lettuces were planted in the field in Salinas, California in the summer and fall of 2003 with four replications. Duplicate samples from each plot were analyzed for chlorophyll (a and b), ß-carotene, and lutein contents by high performance liquid chromatography (HPLC). Primitive, L. serriola, L. saligna, and L. virosa accessions had higher ß-carotene and lutein contents than cultivated lettuces, mainly due to their lower moisture content. Among major types of cultivated lettuce, carotenoid content followed the order of: green leaf or romaine > red leaf > butterhead > crisphead. Crisphead lettuce accumulated more lutein than ß-carotene, while other lettuce types had more ß-carotene than lutein. There was significant genetic variation in carotenoid content within crisphead, butterhead, green leaf, red leaf and romaine types of lettuce. Carotenoid content was higher in summer than in the fall, but was not affected by the position of the plant on the raised bed. ß-Carotene and lutein contents were highly correlated, suggesting that their levels could be enhanced simultaneously. ß-Carotene and lutein contents were both highly correlated with chlorophyll a, chlorophyll b, and total chlorophyll contents, suggesting that carotenoid content could be selected indirectly through chlorophyll or color measurement. These results suggest that genetic improvement of carotenoid levels in lettuce is feasible. |
