Details
| Original language | English |
|---|---|
| Pages (from-to) | 998-1013 |
| Number of pages | 16 |
| Journal | Molecular Plant-Microbe Interactions |
| Volume | 19 |
| Issue number | 9 |
| Publication status | Published - 1 Sept 2006 |
| Externally published | Yes |
Abstract
An effective symbiosis between Sinorhizobium meliloti and its host plant Medicago sativa is dependent on a balanced physiological interaction enabling the microsymbiont to fix atmospheric nitrogen. Maintenance of the symbiotic interaction is regelated by still poorly understood control mechanisms. A first step toward a better understanding of nodule metabolism was the determination of characteristic metabolites for alfalfa root nodules. Furthermore, nodules arrested at different developmental stages were analyzed in order to address metabolic changes induced during the progression of nodule formation. Metabolite profiles of bacteroid-free pseudonodule extracts indicated that early nodule developmental processes are accompanied by photosynthate translocation but no massive organic acid formation. To determine metabolic adaptations induced by the presence of nonfixing bacteroids, nodules induced by mutant S. meliloti strains lacking the nitrogenase protein were analyzed. The bacteroids are unable to provide ammonium to the host plant, which is metabolically reflected by reduced levels of characteristic amino acids involved in ammonium fixation. Elevated levels of starch and sugars in Fix- nodules provide strong evidence that plant sanctions preventing a transformation from a symbiotic to a potentially parasitic interaction are not strictly realized via photosynthate supply. Instead, metabolic and gene expression data indicate that alfalfa plants react to nitrogen-fixation-deficient bacteroids with a decreased organic acid synthesis and an early induction of senescence. Noneffective symbiotic interactions resulting from plants nodulated by mutant rhizobia also are reflected in characteristic metabolic changes in leaves. These are typical for nitrogen deficiency, but also highlight metabolites potentially involved in sensing the N status.
Keywords
- GC-MS, Gene expression profiles, Metabolite profiling
ASJC Scopus subject areas
- Biochemistry, Genetics and Molecular Biology(all)
- Physiology
- Agricultural and Biological Sciences(all)
- Agronomy and Crop Science
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In: Molecular Plant-Microbe Interactions, Vol. 19, No. 9, 01.09.2006, p. 998-1013.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Metabolite profiles of nodulated alfalfa plants indicate that distinct stages of nodule organogenesis are accompanied by global physiological adaptations
AU - Barsch, Aiko
AU - Tellström, Verena
AU - Patschkowski, Thomas
AU - Küster, Helge
AU - Niehaus, Karsten
PY - 2006/9/1
Y1 - 2006/9/1
N2 - An effective symbiosis between Sinorhizobium meliloti and its host plant Medicago sativa is dependent on a balanced physiological interaction enabling the microsymbiont to fix atmospheric nitrogen. Maintenance of the symbiotic interaction is regelated by still poorly understood control mechanisms. A first step toward a better understanding of nodule metabolism was the determination of characteristic metabolites for alfalfa root nodules. Furthermore, nodules arrested at different developmental stages were analyzed in order to address metabolic changes induced during the progression of nodule formation. Metabolite profiles of bacteroid-free pseudonodule extracts indicated that early nodule developmental processes are accompanied by photosynthate translocation but no massive organic acid formation. To determine metabolic adaptations induced by the presence of nonfixing bacteroids, nodules induced by mutant S. meliloti strains lacking the nitrogenase protein were analyzed. The bacteroids are unable to provide ammonium to the host plant, which is metabolically reflected by reduced levels of characteristic amino acids involved in ammonium fixation. Elevated levels of starch and sugars in Fix- nodules provide strong evidence that plant sanctions preventing a transformation from a symbiotic to a potentially parasitic interaction are not strictly realized via photosynthate supply. Instead, metabolic and gene expression data indicate that alfalfa plants react to nitrogen-fixation-deficient bacteroids with a decreased organic acid synthesis and an early induction of senescence. Noneffective symbiotic interactions resulting from plants nodulated by mutant rhizobia also are reflected in characteristic metabolic changes in leaves. These are typical for nitrogen deficiency, but also highlight metabolites potentially involved in sensing the N status.
AB - An effective symbiosis between Sinorhizobium meliloti and its host plant Medicago sativa is dependent on a balanced physiological interaction enabling the microsymbiont to fix atmospheric nitrogen. Maintenance of the symbiotic interaction is regelated by still poorly understood control mechanisms. A first step toward a better understanding of nodule metabolism was the determination of characteristic metabolites for alfalfa root nodules. Furthermore, nodules arrested at different developmental stages were analyzed in order to address metabolic changes induced during the progression of nodule formation. Metabolite profiles of bacteroid-free pseudonodule extracts indicated that early nodule developmental processes are accompanied by photosynthate translocation but no massive organic acid formation. To determine metabolic adaptations induced by the presence of nonfixing bacteroids, nodules induced by mutant S. meliloti strains lacking the nitrogenase protein were analyzed. The bacteroids are unable to provide ammonium to the host plant, which is metabolically reflected by reduced levels of characteristic amino acids involved in ammonium fixation. Elevated levels of starch and sugars in Fix- nodules provide strong evidence that plant sanctions preventing a transformation from a symbiotic to a potentially parasitic interaction are not strictly realized via photosynthate supply. Instead, metabolic and gene expression data indicate that alfalfa plants react to nitrogen-fixation-deficient bacteroids with a decreased organic acid synthesis and an early induction of senescence. Noneffective symbiotic interactions resulting from plants nodulated by mutant rhizobia also are reflected in characteristic metabolic changes in leaves. These are typical for nitrogen deficiency, but also highlight metabolites potentially involved in sensing the N status.
KW - GC-MS
KW - Gene expression profiles
KW - Metabolite profiling
UR - http://www.scopus.com/inward/record.url?scp=33747463644&partnerID=8YFLogxK
U2 - 10.1094/MPMI-19-0998
DO - 10.1094/MPMI-19-0998
M3 - Article
C2 - 16941904
AN - SCOPUS:33747463644
VL - 19
SP - 998
EP - 1013
JO - Molecular Plant-Microbe Interactions
JF - Molecular Plant-Microbe Interactions
SN - 0894-0282
IS - 9
ER -