Investigating the roles of peroxiredoxins and ascorbate on the development and germination of Arabdopsis thaliana seeds

Abstract

At low levels, ROS and especially H2O2 can trigger thiol-based signaling pathways that underlie important physiological processes. In plants, the 1-Cys PRX (PER1) is an enzyme that is highly efficient in H2O2 reduction that is mainly present in the nucleus of cells that take part of seeds. PER1 expression spatially and temporally follows events associated with seed germination. Recently, it was described that PER1 from A. thaliana regulates primary seed dormancy and reduces seed germination by suppressing the abscisic acid (ABA) catabolism and gibberellin (GA) biosynthesis in plant seeds (Chen et al., 2019). The mechanisms by which PER1 regulate seed germination are elusive and probably involve controlling H2O2 levels and the activation of a thiol-based redox machineries that takes place at the first hour of seed imbibition (Nietzel et al., 2020). At this early stage of seed development, hormonal signaling is still not operating (Nietzel et al., 2020). We hypothesize that ascorbate might also be involved in seed development, as it is the only reductant described for PER1 so far (Monteiro et al., 2007; anschau et al., 2020).Therefore, the main goal of the project is to investigate the physiological roles of ascorbate and PER1 in seed development of A. thaliana. Furthermore, our aims are: (i) the identification the PER1 biological reductant(s); (ii) identification of possible PER1 partners;(iii) analysis of the PER1 oxidative state and expression levels during the different stages of seed development and germination and (iv) analyses of landscape of operational cysteinyl thiol redox switches of the nuclear/cytosol by redox proteomic in knockout mutant PER1 and WT. We also intend to perform similar analysis employing a mutant deficient in vitamins C biosynthesis. We planned this BEPE internship in the Dr Markus Schwärzlander´s Laboratory (University of Münster - Germany), as he is an expert in the study of intact seeds employing genetically enconded/fluorescent protein-based in vivo biosensing. In this way, cellular compartmentalization is preserved. Furthermore, we also intend to perform quantitative iodoacetyl tandem mass tag (iodoTMT)-based thiol redox proteomics comparing the mutant PER1 and WT strains, with the advice of Dr. Iris Finkemeiera (University of Münster- Germany), a collaborator of Dr. Schwärzlander. (AU)