Molecular responses of legumes to abiotic stress: protein post-translational modifications and redox signaling
Abstract Legumes include several major crops that are able to fix atmospheric nitrogen in symbiotic root nodules, thus reducing the demand for nitrogen fertilizers and contributing to sustainable agriculture. Global change models predict increases in temperature and more extreme weather conditions. This scenario might increase plant exposure to abiotic stresses and negatively affect crop production. Regulation of whole-plant physiology and nitrogen fixation in legumes during abiotic stress is complex and only a few mechanisms have been elucidated. Reactive oxygen (ROS), nitrogen (RNS), and sulfur (RSS) species are key players in the acclimation and stress tolerance of plants. However, the specific redox-dependent signaling pathways are far from understood. One mechanism by which ROS, RNS, and RSS fulfil their signaling role is the post-translational modification (PTM) of proteins. Redox-based PTMs mostly occur in the cysteine thiol group (oxidation, S-nitrosylation, S-glutathionylation, persulfidation), but also in methionine (oxidation), tyrosine (nitration), and lysine and arginine (carbonylation/glycation) residues. Unraveling PTM patterns under different types of stress and establishing the functional implications may reveal so far unknown underlying mechanisms of the plant and nodule responses to adverse conditions. Here we review the current knowledge on redox PTMs in legumes and their possible consequences in plant and nodule biology.