Harvested Cabbages Still Try to Maintain Circadian Rhythm
FLATOW: So our veggies are sitting there in the supermarket, and they’re doing what?
BRAAM: Well, they are still alive. They are still responding to external stimuli. What we’ve shown is perhaps surprisingly, they can respond to light-dark cycles and really change their metabolite accumulation to different times of day.
FLATOW: They change their metabolism as the sort of a circadian rhythm for my cabbage?
BRAAM: Right, right. So when the crops are growing in the field, they respond to the light-dark cycles, and they – all plants have a circadian rhythm, so they have patterns of behavior that they control or they – that are under the influence of their circadian clock. And when you harvest vegetables and fruits, these vegetables and fruits really stay very much alive even though they’ve been removed from the whole plant. But then when we store them under constant conditions like in constant light in the grocery store, their circadian rhythms begin to dampen. And so then they lose the ability to show these rhythmic behaviors.
FLATOW: And when they’re doing the rhythmic behaviors, there’s got to be a good reason why they’re in a behavior; they’re doing something.
BRAAM: Right. We know from basic plant biology research that plants have these circadian clocks, and we know that they use them in part to respond or to prepare for seasonal changes. But in addition, we recently found that these circadian clocks are also very important for plant defense against insect attack. So plants are able to turn on their defenses at a time when insects are most likely to seed. So in that way, they can prepare for attack before it actually happens. And this is clearly advantageous. Plants are much more resistant to insects if their clocks are functioning properly.