Using DNA from Indian mustard (Brassica juncea ), researchers genetically engineered tomatoes to significantly boost their antioxidant properties. Specifically this new variety reportedly has significantly more vitamin E, lycopene, and provitamin A than traditional tomatoes. The research was described in Plant Biotechnology Journal last month.
Boosting the nutritional value of food crops has long been a goal of scientists. In fact, last week, researchers at Ohio State reported the creation of a yellow-orange lab-engineered potato that had elevated levels of vitamins A and E.
The engineered tomato was created by a team from the University of Hong Kong (HKU) and the Institut de Biologie Moléculaire des Plantes (CNRS). They manipulated the tomato plant’s isoprenoid pathway through the utilization of a variant of 3-hydroxy-3-methylglutaryl-coenzyme A synthase (HMGS). The overexpression of HMGS in tomatoes increased not only phytosterols, squalene, provitamin A, and lycopene, but also vitamin E (α-tocopherol) substantially.
Previously this group reported that the recombinant HMGS variant S359A (in which amino acid residue serine at position 359 was switched to alanine) exhibits 10-fold higher enzyme activity.
In the current experiment, the research group introduced the S359A into tomatoes. Although there were no differences in the appearance and size of the transformed tomato fruits, total carotenoids including provitamin A and lycopene increased by 169% and 111%, respectively. Furthermore, these carotenoid extracts exhibited 89.5-96.5% higher antioxidant activity than the control. Besides carotenoids, the transformed tomatoes displayed elevations in vitamin E (α-tocopherol, 494%), squalene (210%), and phytosterols (94%). These observations were attributed to the increased expression of genes in the isoprenoid pathway.
"Increasing health-promoting components in crops is an important research area that aligns with the aspirations of Dr. Wilson and Mrs. Amelia Wong on the use of plant biotechnology for a sustainable future. The accumulation of the healthy components in food crops would provide added-value to fruits and vegetables in the human diet, as well as enrich feed for livestock and aquaculture," professor Chye Mee-len, research leader, explained.
Image: Hong Kong University scientists show tubes containing carotenoid extracts from S359A tomato fruits and the control.