Structural and Functional Features of Glutathione Reductase Transcripts from Olive (Olea europaea L.) Seeds

The olive seed is a promising by product generated in the olive oil related industries, with increasing interest because of its nutritional value and potential nutraceutical properties. Knowledge concerning the antioxidant capacity of this new alimentary material is scarce. Moreover, oxidative homeostasis and signaling involved physiological processes such as development, dormancy and germination in the olive seed are also unknown. Glutathione (one of the most abundant antioxidants in plant cells), is crucial for seeds physiology, and for defense and detoxification mechanisms. The availability of glutathione in its reduced (GSH) and oxidized (GSSG) forms, the ratio of both forms (GSH/GSSG), and their concurrence in other numerous metabolic pathways is tightly regulated by numerous enzymes. Prominent among these enzymes is glutathione reductase (GR), which has been considered essential for seedling growth and development. The present work aims to increase the knowledge about the functional insights of GR in olive seeds. Searching in the olive transcriptome, at least 19 GR homologues (10 from seed and 9 from vegetative tissue) were identified and retrieved. An in silico analysis was carried out, which included phylogeny, 3-D modelling of the N-terminus, and the prediction of cellular localization and post-translational modifications (PTM) for these gene products. The high variability of forms detected for this enzyme in olive seeds and their susceptibility to numerous PTMs suggest a relevant role for this enzyme in redox metabolism and signalling events.