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The oxidative modifications in the macromolecules of sunflower seed during germination

Abstract : Our work focused on the relationship of cell wall properties and protein oxidation state on dormancy alleviation and germination process. Different dormancy alleviation treatments have been used: afterripening, reactive oxygen species (ROS) and hormone (ethylene). Thus, the study of the change in resistance of the cell wall has shown a decrease in rigidity in treated seeds, able to germinate, compared to dormant ones. Quantification of the identified cell wall monosaccharides did not show any significant difference suggesting the absence of phenomena related to the metabolism of polysaccharides at this stage of germination sensu stricto. Only dormant seeds treated with ROS showed a significant decrease in pectin methylesterase activity, a cell wall enzyme known for its role in elongation and growth. An immunocytological analysis has described a more esterified cell wall in dormant seeds. Thus, the ROS could have a non-enzymatic action while ethylene could act in synergy with the ROS to fulfil the needed relaxation of the cell wall for growth. In addition, a proteomic analysis combining the diagonal chromatography technique with an LC-MS / MS analysis was used on dormant and non-dormant sunflower seeds at different imbibition times in order to identify proteins containing methionine sulfoxyde, a type of reversible protein oxidation. Preliminary analyzes suggest a higher level of protein oxidation in non-dormant seeds. Interestingly, many proteins affected by the oxidation of methionine are related to different biological processes (translation, protein metabolism, energy and metabolism, oxidation-reduction processes) known to be involved in germination, thereby suggesting the importance of methionine oxidation in the regulation of different cellular pathways involved in dormancy emergence and germination.
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Elissa Naim. The oxidative modifications in the macromolecules of sunflower seed during germination. Genomics [q-bio.GN]. Sorbonne Université, 2018. English. ⟨NNT : 2018SORUS536⟩. ⟨tel-02888900⟩

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