| The special nutritional qualities of plants are closely related to diet supplement for human health. Vegetables are good sources of special nutritients for human diets, such as vitamins and phytochemicals. Epidemiological studies have shown that regular consumption of vegetables is associated with reduced risk of chronic diseases, such as cardiscular disease, cancer, diabetes, and age-related functional decline. Therefore, the development of functional food with high special nutritional and healthy values has the potential application market and become the hot spot in the fields of plant genetics and food science.Bean sprouts and lettuce were selected to evaluat the nutritional qualities. The objectives were to determine the effects of germination on phytochemical profiles and antioxidant activity of mung bean sprouts, and to compare the phytochemical profiles and antioxidant activity of six beans and their sprouts. Combined with chemical analysis methods and mammal cell model, the evaluation systems of special nutritional qualities in crops were established to analyze the relationship between special nutrients and health diet. Then four varieties of lettuce (including romaine lettuce, boston lettuce, red-leaf lettuce and green-leaf lettuce) were selected as the representations of green leafy vegetables for analysis the relationship between special nutritional qualities and plant growth. The special nutritional qualities and healthy values were analyzed with the evaluation systems in six varieties of common lettuce, including romaine lettuce, iceberg lettuce, boston lettuce, radicchio lettuce, red-leaf lettuce and green-leaf lettuce. Based on the nutritional and healthy evalution, the selected variety of romaine lettuce was used to bio-fortify the special nutritional qualities by genetic modification methods. Three key enzyme genes of vitamin C biosynthesis pathway were used to transform lettuce by Agrobacterium mediated leaf-disc method, the contributions for vitamin C accumulation among these three genes were evaluated by single gene transformation and combination collocation co-transformation method with double T-DNA vector system. The nutritional qualities were assessed in the high vitamin C content lettuce, the metabolism regulation network were also studied for the impacts of metabolic engineering operation on other secondary metabolism. In view of the special nutrition proportion in romaine lettuce, the optimized metabolic regulation strategy was used to increase the content of vitamin C, folate, carotenoids and human lactoferrin, the marker-free and high multi-nutrients lettuce was obtained. 1) The nutrient contents and biological activity of mung bean sprouts were significantly improved with the extension of germination time before day6. The sprouts were grown up to seedlings followed by the extended stems and stretched euphyllas, even the nutrient content was increased, while ediblility value gradually declined. The best time of germination treatment for mung bean sprouts was6days.2) Based on the nutrient evaluation of time kinetics of mung bean sprouts, the special nutritional qualities of six beans and their sprouts, including mung beans, soybeans, black beans, broad beans, peas and garbanzos, were compared with germination treatment using the evaluation system of "special nutrients analysis→total antioxidant activity→cellular antioxidant activity→biological titer→antiproliferation→cytotoxity". After germination treatment, antioxidant activity and antiproliferation activity were obviously increased following the increased special nutrients in mung bean sprouts, followed by black beans and soybeans. There were no significant changes of antioxidant activity and antiproliferation activity in broad beans before and after germination treatment. Even though the antioxidant activity and antiproferation activity were significantly increased in peas and garbanzos after germination, they were still very low compared with other four legumes. The evaluation system of special nutritional qualities for vegetables were set up and tested by six different legumes.3) The evaluation system of special nutritional qualities were used to evaluate the special nutritional qualities of four varieties of lettuce in three growth stages, such as romaine lettuce, boston lettuce, red-leaf lettuce and green-leaf lettuce. The results showed that vitamin C and phenolic contents were declined with growth up in romaine lettuce, red-leaf lettuce and green-leaf lettuce, while the flavonoid contents were opposite. The special nutrient contents gradually increased in boston lettuce. The total antioxidant activities were obviously related to vitamin C, phenolics and flavonoids with the extended growth stages.4) The evaluation system of special nutritional qualities were used to evaluate among six varieties of lettuce on the shelves, including romaine lettuce, boston lettuce, red-leaf lettuce, green-leaf lettuce, iceberg lettuce and radicchio lettuce. The results showed that vitamin C content was stable, while phenolics and flavonoids were obvious changes in six varieties of lettuce, and the total antioxidant activities were significantly related to phenolics and flavonoids, cellular antioxidant activities were significantly affected by biological values of phytochemicals, there was not a linear correlation between antiproliferation and antioxidant activities.5) Romaine lettuce was chosen for genetic modified object, three key enzyme genes (AtVTC2, AtGLDH, AtDHAR) of vitamin C biosynthesis pathway were single and combined transformated to evaluate the contribution for vitamin C accumulation in lettuce. The chemical assays and cellular model were used to analyze the effects of improved special nutritional qualities in lettuce on antioxidant activity, cytotoxity and cellular availability, transgenic food safety was also analyzed in this evaluation system. The results showed that AtVTC2gene obviously regulated vitamin C metabolism while not affected to other non-target metabolic pathways. Biofortification of vitamin C by genetic engineering can significantly enhance the total antioxidant activity, cellular antioxidant activity and bioavailability.6) Lettuce with biofortified multi-nutrients of vitamin C, folate, carotenoids and human lactoferrin were cultivated by genetic engineering. One marker-free transgenic lettuce were selected from progenies, and vitamin C, folate and carotenoid content in line LsPVFH3were32.6mg/100g FW,207.3μg/100g FW and13.3mg/100g FW, were3,1.9and2.4fold high as wild type; human lactoferrin content was up to396.5μg/100g FW, accounting for3.3%of total protein content, which can provide balanced nutrients for human dietary health and can meet the needs of different levels of consumers.It was the first study to combine food science and plant genetics for improving the special nutritional qualities in crops. The new evaluation systems were established in this study to analyze the special nutritional qualities in crops:special nutrients analysis→total antioxidant activity→cellular antioxidant activity→antiproliferation activity→biology value■> cytotoxity, the evaluation systems can provide the direction for crop nutritional qualities improvement. In accordance with the special nutritional qualities features of romaine lettuce, the optimized metabolic regulation strategy and double Ti-DNA vector were used to obtain the biofortification multi-nutrients and marker-free transgenic lettuce, the nutritional qualities were analyzed for the genetic modified lettuce with the nutritional qualities evaluation system in this study. These results provide theoretical and technical supports for crop nutritional qualities improvement. |
