Peroxisome dynamics and regulation by ROS and pexophagy in response to Cd stress

Peroxisomes, which are highly dynamic and metabolically active organelles, play an important role in cellular functions, including reactive oxygen species (ROS) metabolism. In this study, we show that treatment of Arabidopsis plants with cadmium (Cd) produces peroxisomal extensions called peroxules and further proliferation of peroxisomes, which return to normal numbers after 24 h of treatment. Peroxule formation is mainly regulated by RBOH-dependent ROS production. To determine whether peroxisome abundance is regulated by selective autophagy (pexophagy), we performed a time course analysis of autophagy-related ATG8 proteins and genes and simultaneously imaged peroxisomes and autophagosomes in Arabidopsis plants expressing CFP-SKL and ATG8-GFP. We studied if pexophagy is regulated by ROS by analyzing carbonyl groups and peroxisomal redox state, using the specific biosensor HyperAs, as well as Arabidopsis lines with disturbances in ROS production associated with peroxisomal glycolate oxidase and RBOHs. Our results suggest that peroxules participate in stress perception and that pexophagy is significantly involved in cell responses to environmental cues regulating peroxisomal populations.