The Circadian Clock Coordinates the Tradeoff between Adaptation to Abiotic Stresses and Yield in Crops

SIMPLE SUMMARY: The circadian clock plays a crucial role in helping plants to effectively acclimate to ever-changing environmental conditions. The proper functioning of the circadian clock is integral to the growth and development of plants. In crops, the circadian clock system exerts a multifaceted influence on yield and the response to abiotic stress. This review provides a comprehensive overview of the mechanisms through which the components of a crop’s circadian clock impact its response to abiotic stress and yield. We propose that the circadian clock may orchestrate the balance between abiotic stresses and yield in crops, which is useful for the future molecular design of crop breeding. ABSTRACT: Plants have evolved a circadian clock to adapt to ever-changing diel and seasonal environmental conditions. The circadian clock is generally considered an internal system that has evolved to adapt to cyclic environmental cues, especially diel light and temperature changes, which is essential for higher plants as they are sessile organisms. This system receives environmental signals as input pathways which are integrated by circadian core oscillators to synchronize numerous output pathways, such as photosynthesis, the abiotic stress response, metabolism, and development. Extreme temperatures, salinity, and drought stresses cause huge crop losses worldwide, imposing severe pressure on areas of agricultural land. In crop production, the circadian system plays a significant role in determining flowering time and responding to external abiotic stresses. Extensive studies over the last two decades have revealed that the circadian clock can help balance the tradeoff between crop yield-related agronomic traits and adaptation to stress. Herein, we focus on summarizing how the circadian clock coordinates abiotic stress responses and crop yield. We also propose that there might be an urgent need to better utilize circadian biology in the future design of crop breeding to achieve high yields under stress conditions.