PCP Award
A PROTEINASE-STORING BODY THAT PREPARES FOR CELL DEATH OR STRESSES IN THE EPIDERMAL CELLS OF ARABIDOPSIS

Abstract

A novel compartment with a characteristic structure of ~0.5 m diameter x ~10 m long that accumulated stress-inducible proteinases was found in Arabidopsis thaliana. They are surrounded with ribosomes and are directly derived from the endoplasmic reticulum. Therefore, we propose to call them the ER bodies. Fluorescent ER bodies were observed in transgenic plants of Arabidopsis thaliana expressing GFP fused with an ER retention signal. ER bodies were widely distributed in the epidermal cells of whole seedlings. In contrast, rosette leaves had no ER bodies. We found that wound stress induced the formation of many ER bodies in rosette leaves. ER bodies were also induced by treatment with methyl jasmonate, a plant hormone involved in the defense against wounding and chewing by insects. The induction of ER bodies is a novel endomembrane system in the response of plant cells to environmental stresses.