Harvested vegetables are capable of the same daily cycles as the plants they come from.

Credit: D. GOODSPEED ET AL.

Janet Braam at Rice University in Houston, Texas, and her colleagues set the biological clock of shop-bought cabbages (Brassica oleracea) by exposing them to daily light-dark cycles. The researchers found that the cabbage tissue accumulated chemical defences against herbivores during the light cycle. Intact Arabidopsis plants use the same cycle to guard against pests. When the daily rhythm of the cabbages was synced with that of the plant-munching larvae of the moth Trichoplusia ni (pictured), the vegetables were nibbled less than those whose rhythm was out of sync.

The protective cycling was reproduced in other harvested crops, including blueberries, sweet potatoes and carrots, suggesting that it could be a way to protect fruit and vegetables from pests. The researchers speculate that daily rhythms in harvested produce might also affect its nutrient value.

Curr. Biol. http://dx.doi.org/10.1016/j.cub.2013.05.034 (2013)