For example, a study by used LC-MS to investigate the metabolic changes in the roots of the model legume Medicago truncatula during its symbiosis with the nitrogen-fixing bacterium Sinorhizobium meliloti . The authors identified several metabolites, including flavonoids and triterpene saponins, that were differentially accumulated in the roots during the symbiotic interaction and played important roles in the nodulation process. Similarly, a study by used GC-MS to compare the metabolic profiles of wheat roots colonized by the arbuscular mycorrhizal fungus Funneliformis mosseae and non-colonized roots . The authors identified several metabolites, such as amino acids and organic acids, that were more abundant in the colonized roots and could potentially contribute to the improved nutrient uptake and stress tolerance of mycorrhizal plants.