Selective Autophagy of Peroxisomes in Plants: From Housekeeping to Development and Stress Responses

Abstract

Peroxisomes are dynamic organelles involved in multiple functions, including oxygen and nitrogen reactive species metabolism. In plants, these organelles have a close relationship with chloroplasts and mitochondria, characterized by intense metabolic activity and signal transduction. Peroxisomes undergo rapid changes in size, morphology, and abundance depending on the plant development stage and environmental conditions. As peroxisomes are essential not only for redox homeostasis but also for sensing stress, signaling transduction, and cell survival, their formation and degradation need to be rigorously regulated. In this review, new insights into the regulation of plant peroxisomes are briefly described, with a particular emphasis on pexophagy components and their regulation.

Keywords: autophogy-related genes; peroxins; pexophagy; plants; reactive oxygen species.

Figure 1

Diagram illustrating the elimination of peroxisomal proteins and obsolete/dysfunctional peroxisomes. 1) Peroxisomal proteins can be eliminated by: (A) endogenous peroxisomal proteases such as LON2 or (B) through proteasome degradation in the cytoplasm following ubiquitination. 2) Peroxisomes can be eliminated by: (C) pexophagy, involving three main steps: I) the formation of phagophores when they begin to surround the recyclable peroxisome; II) autophagosome formation when the peroxisome is completely engulfed in the autophagosome and III) vacuolar recycling when the peroxisome inside the vacuole starts to degrade. ROS produced during developmental processes, starvation and biotic or abiotic stresses induce the elimination of peroxisomal proteins, as well as obsolete and dysfuncional peroxisomes. Pexophagy components followed by a question mark in the diagram, whose precise role in plants remains unclear, require further study.