title: Nitrogen-Fixing Nodules Are an Important Source of Reduced Sulfur, Which Triggers Global Changes in Sulfur Metabolism in Lotus japonicus.
abstract: We combined transcriptomic and biochemical approaches to study rhizobial and plant sulfur (S) metabolism in nitrogen (N) fixing nodules (Fix(+)) of Lotus japonicus, as well as the link of S-metabolism to symbiotic nitrogen fixation and the effect of nodules on whole-plant S-partitioning and metabolism. Our data reveal that N-fixing nodules are thiol-rich organs. Their high adenosine 5'-phosphosulfate reductase activity and strong (35)S-flux into cysteine and its metabolites, in combination with the transcriptional upregulation of several rhizobial and plant genes involved in S-assimilation, highlight the function of nodules as an important site of S-assimilation. The higher thiol content observed in nonsymbiotic organs of N-fixing plants in comparison to uninoculated plants could not be attributed to local biosynthesis, indicating that nodules are an important source of reduced S for the plant, which triggers whole-plant reprogramming of S-metabolism. Enhanced thiol biosynthesis in nodules and their impact on the whole-plant S-economy are dampened in plants nodulated by Fix(-) mutant rhizobia, which in most respects metabolically resemble uninoculated plants, indicating a strong interdependency between N-fixation and S-assimilation.
authors: Department of Biotechnology, Agricultural University of Athens, 11855 Athens, Greece.
authors: Chrysanthi
authors: C
authors: Kalloniati
authors: Department of Biotechnology, Agricultural University of Athens, 11855 Athens, Greece.
authors: Panagiotis
authors: P
authors: Krompas
authors: Department of Biotechnology, Agricultural University of Athens, 11855 Athens, Greece.
authors: Georgios
authors: http://orcid.org/0000-0003-4846-6435
authors: G
authors: Karalias
authors: Plant Biology Division, The Samuel Roberts Noble Foundation, Ardmore, Oklahoma 73401.
authors: Michael K
authors: MK
authors: Udvardi
authors: Institute of Forest Sciences, Chair of Tree Physiology, Faculty of Environment and Natural Resources, Albert-Ludwigs-University Freiburg, 79110 Freiburg, Germany College of Science, King Saud University, Riyadh 11451, Saudi Arabia.
authors: Heinz
authors: http://orcid.org/0000-0001-6224-2927
authors: H
authors: Rennenberg
authors: Institute of Forest Sciences, Chair of Tree Physiology, Faculty of Environment and Natural Resources, Albert-Ludwigs-University Freiburg, 79110 Freiburg, Germany.
authors: Cornelia
authors: http://orcid.org/0000-0003-1930-4576
authors: C
authors: Herschbach
authors: Department of Biotechnology, Agricultural University of Athens, 11855 Athens, Greece mflem@aua.gr.
authors: Emmanouil
authors: E
authors: Flemetakis
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D000070116:Lotus / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D059128:Mesorhizobium / Q000235:genetics / Q000502:physiology; D009586:Nitrogen Fixation; D010088:Oxidoreductases / Q000235:genetics / Q000378:metabolism; D050862:Oxidoreductases Acting on Sulfur Group Donors / Q000378:metabolism; D010940:Plant Proteins / Q000378:metabolism; D053204:Root Nodules, Plant / Q000378:metabolism* / Q000382:microbiology*; D013438:Sulfhydryl Compounds / Q000378:metabolism; D013455:Sulfur / Q000378:metabolism*; D013462:Sulfur Radioisotopes / Q000378:metabolism / Q000493:pharmacokinetics; D013559:Symbiosis; D014018:Tissue Distribution; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; C061338:NifA protein, Bacteria; D010940:Plant Proteins; D013438:Sulfhydryl Compounds; D013462:Sulfur Radioisotopes; D014157:Transcription Factors; D013455:Sulfur; D010088:Oxidoreductases; C029130:nitrogenase reductase; D050862:Oxidoreductases Acting on Sulfur Group Donors; C019618:adenylylsulfate reductase