Plant peroxisomes at the crossroad of NO and H2O2 metabolism

Plant peroxisomes are subcellular compartments involved in many biochemical pathways during the life cycle of a plant but also in the mechanism of response against adverse environmental conditions. These organelles have an active nitro‐oxidative metabolism under physiological conditions but this could be exacerbated under stress situations. Furthermore, peroxisomes have the capacity to proliferate and also undergo biochemical adaptations depending on the surrounding cellular status. An important characteristic of peroxisomes is that they have a dynamic metabolism of reactive nitrogen and oxygen species (RNS and ROS) which generates two key molecules, nitric oxide (NO) and hydrogen peroxide (H2O2). These molecules can exert signaling functions by means of post‐translational modifications that affect the functionality of target molecules like proteins, peptides or fatty acids. This review provides an overview of the endogenous metabolism of ROS and RNS in peroxisomes with special emphasis on polyamine and uric acid metabolism as well as the possibility that these organelles could be a source of signal molecules involved in the functional interconnection with other subcellular compartments. Peroxisomes are key organelles involved in all physiological stages of plants. They have an active metabolism in reactive species including H2O2 and NO. Images show the detection by confocal laser scanning microscope of peroxisomes (red) and NO (green) (left and right panels, respectively) in guard cells of Arabidopsis seedlings expressing CFP‐PTS1.