Researchers at Japan's Tohoku University have discovered that plants activate autophagy in their leaf cells to derive amino acids that are used for survival under energy-starved "hunger" conditions. Autophagy is a process where plants "self-eat" the portion of intracellular proteins in their cells.
Drs. Masanori Izumi and Hiroyuki Ishida from Tohoku University had previously demonstrated that plant chloroplasts are actively digested through autophagy during energy starvation. The researchers focused on the precise role of chloroplast-targeted autophagy in the plant survival strategy under low-energy stress. "We hypothesized that chloroplast-associated autophagy is closely linked to the amino acid metabolism in energy-starved plants", said Izumi.
The study reports that when Arabidopsis thaliana is exposed to hunger stress as plants are transferred into complete darkness they can continue to grow for several days; autophagic digestion of chloroplast proteins is rapidly activated and amino acid levels increase. They found that this response during the early stage of hunger stress is suppressed in the mutant plants lacking autophagy machinery.

[www.tohoku.ac.jp]