A metabolic entry point into micro-chlorophagy: insights from impaired maltose metabolism.

As the site of photosynthesis and carbohydrate metabolism, chloroplasts are essential for phototrophic plant growth. The selective elimination of damaged chloroplasts by autophagy, a process known as chlorophagy, is crucial for chloroplast quality control. However, the mechanisms that activate chlorophagy and that underline its specificity remain poorly understood. Our recent study identified changes in maltose metabolism as a previously unrecognized trigger of a micro-chlorophagy program that depends on components of the core autophagy machinery. These findings provide a new starting point for uncovering the molecular principles that govern micro-chlorophagy. Here, we discuss emerging evidence showing that metabolic changes induce autophagic chloroplast turnover and outline the key challenges in defining the signals that initiate micro-chlorophagy.