Title: Integrated analysis of zone-specific protein and metabolite profiles within nitrogen-fixing Medicago truncatula-Sinorhizobium medicae nodules

Abstract

Symbiotic nitrogen fixation (SNF) between rhizobia and legumes requires metabolic coordination within specialized root organs called nodules. Nodules formed in the symbiosis between S. medicae and barrel medic (M. truncatula) are indeterminate, cylindrical, and contain spatially distinct developmental zones. Bacteria in the infection zone II (ZII), interzone II-III (IZ), and nitrogen fixation zone III (ZIII) represent different stages in the metabolic progression from free-living bacteria into nitrogen fixing bacteroids. To better understand the coordination of plant and bacterial metabolism within the nodule, we used liquid and gas chromatography coupled to tandem mass spectrometry (MS) to observe protein and metabolite profiles representative of ZII, IZ, ZIII, whole-nodule, and primary root. Our MS-based approach confidently identified 361 S. medicae proteins and 888 M. truncatula proteins, as well as 160 metabolites from each tissue. The data are consistent with several organ- and zone-specific protein and metabolite localization patterns characterized previously. Here, we used our comprehensive dataset to demonstrate how multiple branches of primary metabolism are coordinated between symbionts and zones, including central carbon, fatty acid, and amino acid metabolism. For example, M. truncatula glycolysis enzymes accumulate from zone I to zone III within the nodule, while equivalent S. medicae enzymes decrease in abundance.more » We also show the localization of S. medicae's transition to dicarboxylic acid-dependent carbon metabolism within the IZ. The spatial abundance patterns of S. medicae fatty acid (FA) biosynthesis enzymes indicate an increased demand for FA production in the IZ and ZIII as compared to ZI. Our observations provide a resource for those seeking to understand coordinated physiological changes during the development of SNF.« less

Authors:

Ogden, Aaron J. ;

• Search DOE PAGES for author "Ogden, Aaron J."
• Search DOE PAGES for ORCID "0000-0002-2041-1072"

Gargouri, Mahmoud; Park, JeongJin; Gang, David R.; Kahn, Michael L.; Mergaert, ed., Peter

Publication Date:

Mon Jul 10 00:00:00 EDT 2017

Research Org.:

Washington State Univ., Pullman, WA (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES)

OSTI Identifier:

1372597

Alternate Identifier(s):

OSTI ID: 1392986

Grant/Contract Number:  

FG03-96ER20225

Resource Type:

Published Article

Journal Name:

PLoS ONE

Additional Journal Information:

Journal Name: PLoS ONE Journal Volume: 12 Journal Issue: 7; Journal ID: ISSN 1932-6203

Publisher:

Public Library of Science (PLoS)

Country of Publication:

United States

Language:

English

Subject:

59 BASIC BIOLOGICAL SCIENCES