Fig. 2

3D-MALDI-FTICR-MSI of soybean root nodule metabolism. a Scheme illustrating the construction of the tomography image from 2D images. Resulting 3D localization of (b) three microscopic anatomical regions imaged by characteristic compounds, where UDP-N-acetyl hexosamine is co-localized with the infection zone, flavonoid glycoside is co-localized with the inner cortex, and soyasaponin is located within the outer cortex of the soybean nodule. The 3D distribution of (c) SAM and d heme B within the soybean root nodule. Mapping the 3D distribution within soybean nodules of the two metabolic pathways involving SAM during BNF: e Polyamine biosynthesis and (f) Phosphatidylcholine biosynthesis. For (f), we mapped the PC (34:1) as an example because we observed the highest number of phospholipid classes with this fatty acid composition. For both (e, f), pathway steps known to occur only in bacterium are annotated