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Tocopherol, Tocotrienol, Vitamin E, Tomato Fruit, Solanum lycopersicum
Abstract:
Summary Tocochromanols constitute the different forms of vitamin E (VTE), essential for the human diet and display a high membrane protectant activity. By combining interval mapping and genome-wide association studies (GWAS) we unveiled the genetic determinants of tocochromanol accumulation in tomato fruits. To enhance the nutritional value of this highly consumed vegetable, we dissected the natural intraspecific variability of tocochromanols in tomato fruits and genetically engineered their biosynthetic pathway. These analyses allowed the identification of a total of 25 QTL interspersed across the genome pinpointing the chorismate-tyrosine pathway as a regulatory hub controlling the supply of the aromatic head group for tocochromanol biosynthesis. To validate the link between the chorismate-tyrosine pathway and VTE, we engineered tomato plants to bypass the pathway at the arogenate branchpoint. Transgenic tomatoes showed moderate increments in tocopherols (up to ~ 20%) and a massive accumulation of tocotrienols (up to ~ 3,400%). Gene expression analyses of these plants reveal a trade-off between VTE and natural variation in chorismate metabolism explained by transcriptional reprogramming of specific structural genes of the pathway. By restoring the accumulation of α-t3 (alfa tocotrienols) in fruits, the plants produced here are of high pharmacological and nutritional interest.
