"Off" Switch for Starch Production in Plants Discovered

A research team from the Weizmann Institute of Science led by Prof. Avihai Danon has discovered the "off" switch for plant starch production. Starch is the most common carbohydrate in the human diet and present in large amounts in staple crops such as rice, potatoes, and maize.

Plants start making starch as soon as the morning light turns on its photosynthesis, and stops when photosynthesis subsides at night. Working with Arabidopsis, the team figured out the chain of biochemical events leading to its shutdown at night. The decrease in light causes a small signaling protein called ACTH4 to lose electrons and become oxidized, which, in turn, quickly prompts it to transmit the "take a break" message to the starch production enzyme.

The team also realized that the mechanism remains active at a low level throughout the day, as if the plant drives its starch production by pressing on the gas pedal and the brakes simultaneously: turning the production on while at the same time keeping it in check. When the scientists genetically engineered the plants to eliminate the "brakes," starch production shot up by nearly 20 percent. This suggests that generally, production efficiency stands at only about 80 percent because the brake pedal is on all the time.

For more details, read the news release from the Weizmann Institute of Science.