The Sorghum circadian system and its role in resilience to environmental stresses

Endogenous circadian time-keeping systems enable plants to anticipate and adapt to changes in their environment. Amongst numerous biological processes regulated by the circadian oscillator in plants are defence responses, photosynthetic capacity, stress-related genes and the control of development. Circadian rhythmic traits (such as period, phase, and amplitude) vary between and within species. Studies have suggested that having a robust circadian system that is correctly synced to the plant’s environment confers a significant advantage for growth and vitality. In crops, the circadian system affects every developmental stage from germination to flowering time and harvest and heavily influences production, biomass and yield.

Sorghum (Sorghum bicolor) is widely grown in developing countries. Although sorghum is more resistant to heat and drought than other cereals, extreme and frequent weather events are making the need to develop more stress-resistant varieties urgent. We predict that the sorghum circadian system may be exploited to optimize growth and resilience to cope with environmental stress. However, the circadian system of this orphan crop is poorly understood. Our main objective is to understand the sorghum circadian system and its role in resilience to environmental stresses. We are making use of a panel of sorghum accessions that originate in diverse habitats across Africa and for which we have extensive eco-geographic data about their sites of origin. Using chlorophyll fluorescence imaging and multi-modelling we are investigating interactions between circadian traits and environmental characteristics in stress and non-stress conditions to identify accessions with circadian rhythm traits that sustainably enhance resilience.