Supermarket Produce Tracks Time

Cabbage, spinach, sweet potatoes, carrots, and other types of produce can respond to the rise and fall of the sun for up to a week after harvest. The ability to track time through cellular circadian clocks has profound implications for the nutritional value of produce and its ability to withstand herbivores, notes a team of plant biochemists led by Janet Braam of Rice University (Curr. Biol. 2013, DOI: 10.1016/j.cub.2013.05.034). The change in light that occurs at sunrise cues plant cells to produce useful phytochemicals. These compounds, including 4-methylsulfinylbutyl glucosinolate, are produced at dawn to deter foraging by insect herbivores that normally feed at that time. Produce stored or transported in constant dark or light conditions may not generate enough of the protective compounds, making “the crop more susceptible to herbivory,” the team notes. Furthermore, continued production of 4-methylsulfinylbutyl glucosinolate is desirable because the compound has anticancer properties. The produce industry may want to synchronize light levels with the sun’s 24-hour cycle to improve the lifetime and nutritional value of produce, the researchers suggest.