Organic Nutrition and Gene Expression in Different Tissues of Chinese Cabbage

To evaluate the nutritional value of Chinese cabbage, carbohydrate, vitamin C, carotenoid and free amino acid levels were measured in six different tissues (leaf and midrib of outer leaves, leaf and midrib of middle leaves, and leaf and midrib of inner leaves) of fully-headed Chinese cabbage. Gene expression associated with the biosynthesis of these compounds was also examined. High levels of starch and vitamin C were detected in the leaves while midrib parts contained low levels. The outer leaf parts contain the lowest level of glucose and sucrose, in contrast to high levels observed in inner parts. However, the outer leaves contained the highest content of carotenoids. While Chinese cabbage contains high levels of Glu, Ala, Asp, and Arg, the levels of most essential amino acids are very low. Transcript levels tested in this study did not correspond to nutrient levels, implying biosynthesis of organic nutrients lacks regulation at the transcriptional level. These results collectively show that although the outer leaves of Chinese cabbage contain more health compounds such as vitamins and carotenoid, the inner leaves are more nutritious.