Abstract
During senescence and times of stress, plants can mobilize needed nitrogen from leaves to other organs. Much of the total leaf nitrogen is allocated to chloroplasts, especially to Rubisco. Despite its important function to allow nutrient recycling, the degradation mechanism of Rubisco is not clearly understood yet. While bulk degradation of the cytosol and organelles in plants occurs by autophagy, its role in the Rubisco degradation is still unclear. A previous study demonstrated Rubisco was released from chloroplasts into specific bodies, named Rubisco-containing bodies (RCBs), in naturally senescent leaves. In this study, we examined the involvement of autophagy on the accumulation and degradation of RCBs using a visualizing method of RCBs in living cells by stroma-targeted fluorescent proteins and autophagy-defective (atg) mutants. We also quantified the RCB number accumulated in different stages of wild-type leaves and the decrease of chloroplast, nitrogen, and Rubisco content in senescent leaves of atg mutants.
