Importance of Daily Rhythms on Brassicaceae Phytochemicals

The circadian clock serves to coordinate metabolism and physiology with the diurnal cycles derived from the daily rotation of the earth. In Brassicaceae, circadian rhythms contribute to the temporal daily variation in diverse phytochemicals and, hence, to both resistance to biotic stress and edible crop health value. Understanding the temporal variation in the specialized metabolites present in Brassica crops can improve selection and future breeding strategies. In this review, we focus on the importance of daily rhythms in the phytochemical biochemistry of the main bioactive compounds present in Brassicaceae plants. We provide a general overview of the mechanisms that can drive the daily variation in phytochemical levels and then provide specific examples of compounds that show daily variation. Finally, we discuss how these rhythmic patterns in plant phytochemicals may impact plant protection against biotic stress, the content of nutraceuticals, and the longevity of post-harvest crops.