Cell- and tissue-specific transcriptome analyses of Medicago truncatula root nodules

We used laser-capture microdissection (LCM) to isolate specific cells from the Medicago truncatula nodule meristem (M), the distal infection (DIZ), the proximal infection zone (PIZ), infected cells (IC) and uninfected cells (UIC) from the fixation zone. Based on Medicago GeneChips, we identified the cell- and tissue-specific programm of gene expression in Medicago truncatula root nodules. Nodules were harvested three weeks after inoculation of Medicago truncatula (genotype Jemalong A17) plants with Sinorhizobium meliloti strain 2011. Nodules were fixed in Farmer's fixative and subsequently embedded in paraffin. 8 µm de-paraffined sections were used to capture cells from the nodule meristem, distal infection zone, proximal infection zone, infected cells and uninfected cells from the fixation zone, using an Arcturus Pixcell II laser capture microscope. 3 biological replicates were used for each cell-/tissue type. After RNA extraction, the RNA was amplified and used for Medicago Gene Chip hybridization.