Dynamic Changes in Vitamin E Biosynthesis during Germination in Brown Rice (Oryza sativa L.)

The present study investigated the dynamic changes in vitamin E and gene expression within its biosynthetic pathway during three germination periods of four brown rice cultivars with different seed coat colors. The results reveal that the vitamin E content increased during the germination process of all brown rice cultivars. Moreover, the content of α-tocopherol, α-tocotrienol, and β-tocopherol significantly increased at the later stage of germination. The expression levels of DXS1 and γ-TMT genes in all cultivars were significantly increased, whilst the HGGT gene expression levels of G6 and XY cultivars increased significantly at the later stage of brown rice germination. In addition, the expression levels of MPBQ/MT2 in G1 and G6 cultivars, and TC expression levels in G2 and G6 cultivars were substantially increased at the later stage of germination. Overall, the up-regulation of MPBQ/MT2, γ-TMT, and TC genes doubled the content of α-tocopherol, α-tocotrienol, and β-tocopherol, and the total vitamin E content of brown rice was at its highest at 96HAT. The utilization of the germination period can effectively improve the nutritional value of brown rice, which can be used for the development and utilization of brown rice for healthy rice products.