Expression of Carotenoid Biosynthetic Genes and Carotenoid Biosynthesis during Seedling Development of Momordica charantia

Carotenoids belong to a large group of secondary metabolites, and have pivotal roles in plants, including photosynthesis and phytohormone synthesis, pigmentation, and membrane stabilization. Additionally, carotenoids are potent antioxidants, and their health benefits are becoming increasingly prominent. In recent years, carotenoids have been studied in many plants. Furthermore, gene expression, as well as carotenoid accumulation in different parts of the bitter melon, has been investigated; however, it has not been studied in bitter melon seedlings. In this study, carotenoid accumulation and transcript levels of McGGPPS1, McGGPPS2, McPSY, McPDS, McZDS, McLCYB, McLCYE1, McLCYE2, McCXHB, and McZEP, involved in carotenoid biosynthesis, were analyzed during seedling development using HPLC and qRT-PCR. The major carotenoids that accumulated in the bitter melon seedlings were lutein and E-β-carotene. The expression of most carotenoid biosynthetic genes increased during seedling development, consistent with the accumulation of violaxanthin, lutein, zeaxanthin, β-cryptoxanthin, 13Z-β-carotene, E-β-carotene, and 9Z-β-carotene in bitter melon seedlings. The results of this study provide a firm basis for comprehending the link between gene expression and carotenoid concentration in bitter melon seedlings.