Studying the Role Of Autophagy Under Excess Carbon Conditions

Autophagy, self-eating, plays an important role in eukaryotic intracellular recycling. the targets of autophagy range from a single protein to an entire organelle. The component is engulfed by the forming vesicle, autophagosome, which is then fused to the lytic organelle (lysosome/vacuole) for degradation. The degradation products are exported to the cytosol for re-use. Starvation and stress conditions upregulate autophagy.

Sugars in plants play a vital role not only in energy homeostasis but also as regulators of developmental processes. High sugar levels cause stress which can lead to growth arrest during germination/post-germination growth. Autophagy mutant plants are known to be hypersensitive to carbon starvation and display altered carbon metabolism. Yet, not much is known about the effect of sugar excess on the autophagy mechanism.

In our research, we grew autophagy mutant and WT Arabidopsis thaliana plants on plates containing sucrose concentrations from 0%-4%. One prominent phenotype was the root length. Between 0-1% sucrose, there was no significant difference between the lines. when Exposed to 2-4%, the roots were shortened but the mutants showed longer roots relative to WT. Similar results were achieved by equivalent molar ratio of glucose. When adding fructose, no significant change occurred.

Photosynthetic activity assay revealed no significant difference in photosynthesis efficiency between the lines when using 0-4% sucrose mediums. Future metabolomic analysis would give further understanding regarding molecular differences under high carbon stress. Overall, Understanding the role of autophagy in mediating carbon response under high sugar levels would help us understand its role in carbon homeostasis.