Betalains are made by cactus fruit, flowers such as bougainvillea and certain edible plants – most notably, beets. They are relatively rare in nature, compared to the two other major groups of plant pigments, and until recently, their synthesis in plants was poorly understood.
Now, Weizmann Institute’s Prof. Asaph Aharoni and Dr. Guy Polturak have used two betalain-producing plants – red beet and four o’clock flowers – to identify a previously unknown gene involved in betalain synthesis and reveal which biochemical reactions plants use to produce betalains.
Colors can be altered on demand
To test their findings, the researchers genetically engineered yeast to produce betalains. They then tackled the ultimate challenge: reproducing betalain synthesis in edible plants that do not normally make these pigments.
The researchers produced red-violet potatoes, tomatoes and eggplants. They also managed to control the exact location of betalain production by, for example, causing the pigment to be made only in the fruit of the tomato plant but not in the leaves or stem.
Using the same approach, the scientists caused white petunias to produce pale violet flowers, and tobacco plants to flower in hues varying from yellow to orange pink. They were able to achieve the desired hue by causing the relevant genes to be expressed in different combinations during the course of betalain synthesis.
Their findings, which were recently published in the scientific journal Proceedings of the National Academy of Sciences, may also be used to create ornamental plants with colors that can be altered on demand.
Healthy antioxidant activity was 60 percent higher
But the change in color was not the only outcome. Healthy antioxidant activity was 60 percent higher in betalain-producing tomatoes than in average ones. “Our findings may in the future be used to fortify a wide variety of crops with betalains in order to increase their nutritional value,” Aharoni said in a statement.
Aharoni and his team also discovered that betalains protect plants against gray mold, Botrytis cinerea, which annually causes losses of agricultural crops worth billions of dollars. The study showed that resistance to gray mold rose by a whopping 90 percent in plants engineered to make betalains.
The scientists produced versions of betalain that do not exist in nature. “Some of these new pigments may potentially prove more stable than the naturally occurring betalains,” Polturak said. “This can be of major significance in the food industry, which makes extensive use of betalains as natural food dyes, for example, in strawberry yogurts.”
Furthermore, the findings of the study may be used by the pharmaceutical industry. According to the researchers, the chemical process by which plants produce betalains could serve as a starting material in the manufacturing of drugs, particularly opiates such as morphine.
source: No Camel
Images: Courtesy of the Weizmann Institute