Isolating intact chloroplasts from small Arabidopsis samples for proteomic studies

We have established a method for the isolation of chloroplasts from Arabidopsis thaliana that allows proteomic studies in the context of biotic stress with small amounts of starting material. Employing a 50% Percoll layer to separate crude filtrates, the required leaf material was reduced to 2–3 g, yielding more than 300 μg of chloroplast proteins. The quality of this fraction was confirmed by immunological, enzymatic, and gel-based assays. This protocol provides intact chloroplasts from Arabidopsis plants with a high degree of integrity and purity as well as sufficient protein recovery, thereby enabling studies of plant–herbivore or plant–pathogen interactions.