Daily light-dark cycles regulate the circadian clock, a biological clock which induces 24-hours oscillations in physiological functions such as the secretion of metabolites or hormones.

Danielle Goodspeed, Rice University, Huston, USA, and colleagues discovered that the chemistry of cabbages is deeply influenced by the circadian clock. The researchers measured the production of 4-methylsulfinylbutyl (4MSO), an antitumoral and antimicrobial metabolite. They demonstrated that 4MSO levels fluctuate over time in cabbages exposed to light-dark cycles. As a consequence, 4MSO reach maximal concentrations only at certain hours of the day. While the oscillations in 4MSO production occurred even when light-dark cycles were applied to post-harvest cabbages, they were lost when cabbages were maintained under constant light or darkness.

Thus, in order to enhance the healthy value of cabbages, it might be important to timely harvest them and to store them under light-dark cycles.

• Postharvest Circadian Entrainment Enhances Crop Pest Resistance and Phytochemical Cycling,
  Danielle Goodspeed, John D. Liu, E. Wassim Chehab, Zhengji Sheng, Marta Francisco, Daniel J. Kliebenstein, Janet Braam,
  Current Biology 2013.
  DOI: 10.1016/j.cub.2013.05.034