Abstract
Autophagy is an intracellular process for vacuolar degradation of cytoplasmic components. In yeast, we previously found that the C-terminus of Atg8 protein is modified with a lipid molecule by ubiquitination-like reaction after cleavage of its C-terminus by Atg4 protease. These Atg8 lipidation reactions are essential for yeast autophagy. Arabidopsis homologues of ATG8 and ATG4 (AtATG8s, AtATG4s) are supposed to function in a similar way in plant autophagy. Yeast Atg8 is known to be delivered to the vacuole as a consequence of autophagic process. This time, transgenic Arabidopsis expressing GFP-AtATG8 were observed by fluorescence microscopy. In wild-type plants, GFP-AtATG8s, which are localized on some ring structures in the cytoplasm, were delivered to the lumens of vacuole under nitrogen-starvation condition. However, in T-DNA insertion double mutant of AtATG4, GFP-AtATG8s were not delivered to the vacuole under nitrogen-starvation condition. This will provide a monitoring system assessing autophagic process in a whole plant.
