Braam’s team at Rice has found that the circadian rhythm in certain plants also determines when they launch chemical defenses against predators. A 2012 study on Arabidopsis, a highly studied flowering plant related to cabbage, found that the plant’s circadian cycle helps ward off cabbage looper caterpillars. A set of plants kept on a normal day/night cycle anticipated the time the caterpillars typically eat and gave off a pungent chemical to discourage feeding. Plants forced on a light cycle 12 hours out of phase didn’t do this and were thus chewed up.
And in a study from last June, the researchers showed that cabbage retains its circadian rhythm after harvest, including the cyclical production of a chemical called 4MSO, which may have anti-cancer properties.