Genetic variation and relationship among content of vitamins, pigments, and sugars in baby leaf lettuce

Authors: Simko, Ivan

Submitted to: Food Science and Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/12/2019
Publication Date: 10/22/2019
Citation: Simko, I. 2019. Genetic variation and relationship among content of vitamins, pigments, and sugars in baby leaf lettuce. Food Science and Nutrition. 7(10):3317–3326. https://doi.org/10.1002/fsn3.1196.
DOI: https://doi.org/10.1002/fsn3.1196

Interpretive Summary: Lettuce is the most popular, commercially grown leafy vegetable in many countries around the world. Lettuce leaves, which are mainly consumed raw, contain dietary fiber, several important dietary minerals, vitamins (e.g., vitamin B9 and vitamin C), and bioactive compounds (e.g., carotenoids and phenolic compounds) that contribute to human nutritional benefits. Baby leaf lettuce is the primary component of spring mix salads that are popular type in packaged salads. Lettuce for baby leaf production is harvested when the first four true leaves reach the length of ca. 5 - 13 cm, approximately 30-days after planting. Significant differences among 42 tested accessions were found for content of vitamin C, ß-carotene, anthocyanins, chlorophylls, glucose, fructose, sucrose, sucrose sweetness equivalency (SSE), and average vitamin load (AVLAC). Cultivar (cv.) Floricos was highest in sugars content and SSE; cv. Taiwan was highest for AVLAC, and cultivars Annapolis and Darkland were highest for anthocyanins and chlorophyll contents, respectively. There were very strong, positive correlations among contents of the three sugars, and between ß-carotene and vitamin C, and ß-carotene and anthocyanins. Phenotypic profiles of accessions presented in this study, together with identified associations between compounds can be used by breeders, growers, and producers to select lettuces with desirable combinations of sugars, pigments, and vitamins. This information can help in development of new cultivars and breeding lines with desirable combination of traits, pleasing taste and higher vitamin content.

Technical Abstract: Baby leaf lettuce harvested approximately 30-days after planting is the primary component of spring mix salads, a popular type of packaged salads. Most previous studies related to contents of vitamins, pigments, and sugars in lettuce were performed on plants harvested at marketable maturity (ca. 60-90 days after planting); relatively little is known about the contents of these compounds in baby leaf lettuce. Young lettuce plants were, therefore, analyzed for the contents of vitamin C, ß-carotene, anthocyanins, chlorophylls, glucose, fructose, and sucrose in 42 lettuce accessions. Significant differences among accessions were found in the contents of all seven compounds, sucrose sweetness equivalency (SSE) and average vitamin load (AVLAC). Highest content of sugars and SSE was detected in cv. Floricos; while the highest AVLAC was found in cv. Taiwan. Cultivars Annapolis and Darkland had the highest content of anthocyanins and chlorophylls, respectively. There were very strong, positive correlations among the contents of the three sugars, between ß-carotene and vitamin C, and ß-carotene and anthocyanins. Phenotypic profiles of accessions presented in this study, together with identified associations between compounds can be used by breeders, growers, and producers to select lettuces with desirable combinations of sugars, pigments, and vitamins. The results may help in developing new cultivars and breeding lines with desirable combination of traits, pleasing taste and higher vitamin content.