Project description:12plex_medicago_2014_02 - nar nodule vs root transcriptome - which are the genes differentially expressed in alfalfa spontaneous (non rhizobium-infected) nodules vs. control roots? - biological material: aeroponically grown cuttings of a Medicago sativa (alfalfa) accession that produces empty nodules when nitrogen-starved. Samples for transcriptome comparison: isolated NAR nodules (10 days post N-starvation) vs. roots of the same plants (pools of 3 roots).
Project description: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.
Project description: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 M-BM-5m 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.
Project description:To understand the role of Medicago truncatula NODULE INCEPTION (MtNIN) in nodule development, we analyzed the transcriptome of roots ectopically overexpressing NIN, nodules of weak mutant allele nin-16, and nodules of dnf1-2 mutant.
Project description:Nitrogen assimilation in plants is a tightly regulated process that integrates developmental and environmental signals. The legume-rhizobial symbiosis results in the formation of a specialized organ called root nodule, where the rhizobia fixes atmospheric nitrogen into ammonia. Ammonia is assimilated by the plant enzyme glutamine synthetase, which is specifically inhibited by PPT. The expression of key genes related to the regulation of root nodule metabolism will likely be affected by glutamine synthetase inhibition. We used microarrays to detail the global programme of gene expression in response to Glutamine synthetase inhibition in root nodules and identified genes differentially expressed over a time course. Medicago truncatula nodulated plants (20 days post inoculation) were treated with 0.25 mM of PPT. Root nodules were harvested at 4, 8 and 24 hours after PPT application. As a control, root nodules collected just before PPT application were used (PPT 0h). Three biological replicates consisting of pools of root nodules harvested from five distinct plants were used for RNA extraction and hybridization on Affymetrix GeneChips.
Project description:Root nodule microbial communities from Medicago polymorpha collected in Santa Monica, California, United States - pink nodules metagenome
Project description:Root nodule microbial communities from Medicago polymorpha collected in Santa Monica, California, United States - brown nodules metagenome
Project description:The bacterium, Sinorhizobium meliloti, interacts symbiotically with leguminous plants such as Medicago truncatula to form nitrogen-fixing root nodules. During symbiosis, plant and bacterial cells differentiate in a coordinated manner, resulting in specialized plant cells that contain nitrogen-fixing bacteroids. Medicago nodules are organized in structurally distinct tissue zones, representing different stages of bacterial and plant differentiation. We used laser-capture microdissection (LCM) to analyze bacterial and plant gene expression in four root nodule regions. In parallel, we analyzed gene expression in nodules formed by wild type bacteria on six plant mutants with nitrogen fixation deficiencies (dnf). We found that bacteroid metabolism is drastically remodeled during bacteroid differentiation. Many processes required for bacterial growth are down-regulated in the nitrogen fixation zone. The overall transcriptional changes are similar to those occurring during nutrient limitation by the stringent response. We also observed differential expression of bacterial genes involved in nitrogen fixation, cell envelope homeostasis, cell division, stress response and polyamine biosynthesis at distinct stages of nodule development. In M. truncatula we observed the differential regulation of several host processes that may trigger bacteroid differentiation and control bacterial infection. We analyzed plant and bacterial gene expression simultaneously, which allowed us to correlate processes in both organisms.