A proteomic approach to understand the impact of nodulation on salinity stress response in alfalfa (Medicago sativa L.)

Abstract Background Symbiotic nitrogen fixation in legumes is an important source of nitrogen supply in sustainable agriculture. Salinity is a key abiotic stress that negatively affects host plant growth, rhizobium-legume symbiosis and nitrogen fixation.Results To explore how the symbiotic relation impacts plant response to salinity, we assayed the proteome profile of alfalfa plants with active nodules (NA), inactive nodules (NI) or without nodules (NN) when plants were subjected to salinity stress. Our data suggested that NA plants respond to salinity stress through some unique signaling regulations. NA plants showed an upregulation of proteins related to cell wall remodeling and reactive oxygen species (ROS) scavenging and a down-regulation of proteins involved in protein synthesis and degradation. The data also showed that NA plants, together with NI plants, upregulated proteins in photosynthesis, carbon fixation and respiration, anion transport, and plant defense to pathogens.Conclusions The data suggest that the symbiotic relations conferred the host plant a better capacity to adjust the key processes, probably to more efficiently use energy and resources, deal with oxidative stress, and maintain ion homeostasis and healthy status during salinity stress.