Multifaceted Investigation of Metabolites During Nitrogen Fixation in the Medicago truncatula-Sinorhizobium meliloti Symbiosis via MALDI-MS Imaging and High-Resolution ESI-MS

摘要

Legumes are extrernely important to the sustainability of agricultural systems because of their ability to fix nitrogen through a symbiotic association with soil bacteria known as rhizobia. Efficient biological nitrogen fixation (BNF) depends on metabolites produced by and exchanged between both partners. This work presents a multifaceted mass spectrornetric approach to detect and identify key metabolites that are present during BNF using the Medicago truncatual-Sinorhizobium meliloti association as the model system. The combination of wild type (wt) plants and wt rhizobia produce functional nodules, capable of nitrogen fixation. Well-characterized mutants of Medicago (dnf1) and rhizobia (fixJ) produce nodules that are incapable of nitrogen fixation. Combinations of Medicago-rhizobia (wt-wt. wt-fixJ, dnf1-wt, dnf1-fixJ) were compared to determined metabolites that play a significant role in BNF. High resolution MALDI-Orbitrap and ESI-Q-Exactive mass spectrometers were used to generate complementary data for a through investigation of the metabolites involved in the BNF process.