EAGER: Uncovering Mechanistic Link Between Autophagy and Circadian Clock in Arabidopsis

University Of California-Davis, Davis CA

Investigators

Abstract

During the daytime plants use carbohydrate generated through photosynthesis to support their growth and development. To avoid starving in the night when photosynthesis is not possible, plants store some of the carbohydrate produced in the day as starch reserve for nighttime use. In Arabidopsis plants, 95% of the stored starch is consumed by dawn. Interestingly, the 24-hour circadian clock controls the rate of starch degradation so that the appropriate amount of starch is used by dawn irrespective of the length of the night. The precise molecular processes involved in clock-controlled nighttime starch usage are not understood. Recently, the autophagy (self-eating) process has been implicated in nighttime starch degradation. This project will investigate the inter-relationship between the clock and autophagy using the Arabidopsis plant as the model system. Results from these studies should provide strategies to improve plant productivity by maintaining the appropriate day-night energy balance especially during changes in environmental conditions. Through its broader impacts, project will train a research scientist, a post-doctoral fellow, and an undergraduate student from Biology Undergraduate Scholars Program (BUSP). Autophagy is a dynamic process during which double membrane-bound vesicles called autophagosomes enclose cytoplasmic materials and target them to the vacuole/lysosome for degradation or recycling. Autophagy (Atg) core proteins are conserved among eukaryotes including Arabidopsis model plant. The ubiquitin-like modifier Atg8 plays a key role in autophagosome biogenesis, cargo recruitment, and autophagosme delivery to the vacuole/lysosome. Arabidopsis Atg8 interaction studies uncovered an intriguing module consisting of Arabidopsis circadian clock components. This project will investigate the possible molecular link between Arabidopsis autophagy and the circadian clock. The project will specifically investigate whether circadian clock regulates autophagy and whether autophagy in turn regulates clock function in Arabidopsis. Understanding the mechanistic link between autophagy and circadian system should provide insights on carbon assimilation and energy homeostasis in plants.