Peroxisomes and ROS Under Stress Conditions

Abstract

Peroxisomes are small, single-membrane confined organelle, appearing ubiquitously in eukaryotic organisms. Despite being simple in structure, it is a highly dynamic organelle, which caters multiple metabolic functions, essentially needed for expansion and development of plant. The metabolic pathways occurring in peroxisomes, in particular, photorespiration, catabolism of fatty acid via β-oxidation, activity of peroxisomal enzymes, dismutation of superoxide radical (O2•−), and breakdown of polyamines, generate reactive oxygen species (ROS). The genesis of ROS, particularly, hydrogen peroxide (H2O2) elevates under biotic and abiotic stress conditions, which act either as an inducer of oxidative stress or signal transducing molecules. The action of ROS is a characteristic function of their accumulated concentration in peroxisomes. The presence of ROS in excess induces post-translational modification of biomolecules which damage their structure and alter the function. The cell however is equipped with antioxidants, which include an array of enzymes and non-enzymatic molecules, quenching excess ROS, which aid in maintaining cellular redox homeostasis. Catalase is the prime enzymatic antioxidant present in peroxisomes, which scavenges excess H2O2, attenuating their accumulation in the organelle. The low concentration of ROS, specifically, H2O2 mediates retrograde signaling under stress conditions. The H2O2 diffuses out into the cytosol and alters expression of various nuclear gene, eventually leading to stress tolerance. A clear understanding of mechanisms occurring within plant cells is essential to improve crop production under stress. We summarize the knowledge pertaining to ROS metabolism in plant peroxisomes under unfavorable conditions to improve the understanding. A better insight into the ROS metabolism in peroxisomes provides avenues for future research to safeguard crop production under changing climatic conditions.