In situ metabolic profiling of symbiotic soybean-rhizobia interactions by laser ablation -electrospray ionization mass spectrometry (LAESI-MS)
B. AGTUCA (1), S. Stopka (2), C. Anderton (3), D. Koppenaal (3), L. Pasa-Tolic (3), A. Vertes (2), G. Stacey (1) (1) Divisions of Plant Sciences and Biochemistry, C. S. Bond Life Sciences Center, University of Missouri, U.S.A.; (2) Department of Chemistry, W. M. Keck Institute for Proteomics Technology and Applications, The George Washington University, U.S.A.; (3) Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, U.S.A.

Plants synthesize specific compounds (e.g., metabolites) that are essential for biochemical processes, such as growth, development, and responses to perturbations. Recent advancements in metabolomics have expanded and clarified plant biochemistry, genetics, and physiology under varying conditions. However, the spatiotemporal information about metabolite production, storage, and transport remains largely elusive. In recent years, laser ablation electrospray ionization mass spectrometry (LAESI-MS) has demonstrated success in metabolomic studies of a wide range of samples from microalgae to plant tissues. This ambient analysis method requires minimal sample preparation, while preserving the spatial information of biomolecules from samples in their native state. Here, we used LAESI-MS to investigate the metabolites in nitrogen-fixing soybean nodules resulting from root infection by Bradyrhizobium japonicum. Whole root nodules were subjected to nanosecond mid-IR laser pulses in order to obtain metabolic profiles throughout the different nodule cellular layers. B. japonicum wildtype and fix-mutant (nifH) strains were used as inoculants in order to spatially and chemically define unique biomarkers associated with nitrogen fixation. For LAESI-MS data processing, statistical and hierarchical clustering analyses were performed to compare the semi-quantification of metabolites between the host roots and the bacteroids within the nodule. Preliminary results showed specific metabolites that were involved in nitrogen fixation. The data demonstrate that the LAESI-MS method, especially coupled with new, ultra-high mass resolution and mass accuracy MS, holds tremendous potential for use in further studies of plant-microbe interactions, as well as other plant processes.

Abstract Number: C13-4, P19-707
Session Type: Concurrent