Drought stress provokes the down‐regulation of methionine and ethylene biosynthesis pathways in Medicago truncatula roots and nodules

• DOI: 10.1111/pce.12285
• Publication Date: 2014-01-29T08:19:28Z
• Authors: ESTÍBALIZ LARRAINZAR; JOHANNA A. MOLENAAR; STEFANIE WIENKOOP; ERENA GIL‐QUINTANA; BÉNÉDICTE ALIBERT; ANIS M. LIMAMI; CESAR ARRESE‐IGOR; ESTHER M. GONZÁLEZ
• Keywords: 0301 basic medicine; acetylene-reduction assay; Proteome; proteome; [SDV]Life Sciences [q-bio]; Down-Regulation; nitrogen-fixation; soybean nodules; arabidopsis-thaliana; Antioxidants; n-2 fixation; Sulfur metabolism.; 03 medical and health sciences; Methionine; 106023 Molekularbiologie; Gene Expression Regulation, Plant; Stress, Physiological; Nitrogen Fixation; Medicago truncatula; Photosynthesis; Symbiosis; water-deficit; sucrose synthase; 2. Zero hunger; 580; atp sulfurylase; signal-transduction pathway; Sulfur metabolism; Sulfates; Water; Methionine Adenosyltransferase; 15. Life on land; 106023 Molecular biology; Ethylenes; Glutathione; 6. Clean water; symbiosis; Biosynthetic Pathways; Droughts; Molecular Weight; 106030 Pflanzenökologie; sulfur metabolism; cystathionine gamma-synthase; 106030 Plant ecology; Amino Acid Oxidoreductases; Root Nodules, Plant; Sulfur

AbstractSymbiotic nitrogen fixation is one of the first physiological processes inhibited in legume plants under water‐deficit conditions. Despite the progress made in the last decades, the molecular mechanisms behind this regulation are not fully understood yet. Recent proteomic work carried out in the model legume Medicago truncatula provided the first indications of a possible involvement of nodule methionine (Met) biosynthesis and related pathways in response to water‐deficit conditions. To better understand this involvement, the drought‐induced changes in expression and content of enzymes involved in the biosynthesis of Met, S‐adenosyl‐L‐methionine (SAM) and ethylene in M. truncatula root and nodules were analyzed using targeted approaches. Nitrogen‐fixing plants were subjected to a progressive water deficit and a subsequent recovery period. Besides the physiological characterization of the plants, the content of total sulphur, sulphate and main S‐containing metabolites was measured. Results presented here show that S availability is not a limiting factor in the drought‐induced decline of nitrogen fixation rates in M. truncatula plants and provide evidences for a down‐regulation of the Met and ethylene biosynthesis pathways in roots and nodules in response to water‐deficit conditions.