Plants keep one foot on the brakes

We studied the mechanisms controlling the plant production of starch, which is the most common carbohydrate in the human diet and present in large amounts in such staple crops as rice, potatoes and maize.

We have discovered the "off" switch for starch production.

Working with a mustard-like plant called Arabidopsis, we 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.