Arabidopsis APx-R is a plastidial ascorbate-independent peroxidase regulated by Photomorphogenesis

• Main Author: Lazzarotto, Fernanda
• Publication Date: 2021
• Other Authors: Wahni, Khadija, Piovesana, Maiara, Maraschin, Felipe dos Santos, Messens, Joris, Margis-Pinheiro, Márcia
• Format: Article
• Language: eng
• Source: Repositório Institucional da UFRGS
• Download full: http://hdl.handle.net/10183/268385
• topic: Ascorbato peroxidases; Fotomorfogênese; Genética vegetal; Ascorbate; Peroxidase; Photomorphogenesis

Peroxidases are enzymes that catalyze the reduction of hydrogen peroxide, thus minimizing cell injury and modulating signaling pathways as response to this reactive oxygen species. Using a phylogenetic approach, we previously identified a new peroxidase family composed of a small subset of ascorbate peroxidase (APx) homologs with distinguished features, which we named ascorbate peroxidase-related (APx-R). In this study, we showed that APx-R is an ascorbate-independent heme peroxidase. Despite being annotated as a cytosolic protein in public databases, transient expression of AtAPx-R-YFP in Arabidopsis thaliana protoplasts and stable overexpression in plants showed that the protein is targeted to plastids. To characterize APx-R participation in the antioxidant metabolism, we analyzed loss-of-function mutants and AtAPx-R overexpressing lines. Molecular analysis showed that glutathione peroxidase 7 (GPx07) is specifically induced to compensate the absence of APx-R. APx-R overexpressing lines display faster germination rates, further confirming the involvement of APx-R in seed germination. The constitutive overexpression of AtAPx-R-YFP unraveled the existence of a post-translational mechanism that eliminates APx-R from most tissues, in a process coordinated with photomorphogenesis. Our results show a direct role of APx-R during germinative and post-germinative development associated with etioplasts differentiation.