In vivo quantification of peroxisome tethering to chloroplasts in tobacco epidermal cells using optical tweezers

Abstract

Peroxisomes are highly motile organelles that display a range of motions within a short time frame. In static snapshots they can be juxtaposed to chloroplasts which has led to the hypothesis that they are physically interacting. Here, using optical tweezers we have tested the dynamic physical interaction in vivo. Using near-infrared optical tweezers, combined with TIRF microscopy, we were able to trap peroxisomes and approximate the forces involved in chloroplast association in vivo, and observed weaker tethering to additional unknown structures within the cell. We show that chloroplasts and peroxisomes are physically tethered through peroxules, a poorly described structure in plant cells. We suggest peroxules have a novel role in maintaining peroxisome-organelle interactions in the dynamic environment. This could be important for fatty acid mobilisation and photorespiration through interaction with oil bodies and chloroplasts, highlighting a fundamentally important role for organelle interactions for essential biochemistry and physiological processes.