Mineral nitrogen inhibition and signal production in soybean-B. japonicum symbiosis
In the N2 fixing legume symbiosis, mineral nitrogen (N) not only decreases N2 fixation, but also delays and inhibits the formation and development of nodules. The purposes of this thesis were to elucidate the role of signaling in the mineral N effects on nodulation and nitrogen fixation in soybean [...
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ndltd-LACETR-oai-collectionscanada.gc.ca-QMM.366702014-02-13T03:43:08ZMineral nitrogen inhibition and signal production in soybean-B. japonicum symbiosisIsoflavonoids and nitrogen inhibition in soybean-B. japonicum symbiosisPan, Bo, 1963-Soybean.Rhizobium japonicum.Nitrogen-fixing microorganisms.Plant cellular signal transduction.In the N2 fixing legume symbiosis, mineral nitrogen (N) not only decreases N2 fixation, but also delays and inhibits the formation and development of nodules. The purposes of this thesis were to elucidate the role of signaling in the mineral N effects on nodulation and nitrogen fixation in soybean [Glycine max (L.) Merr.] and to attempt to find ways to overcome this inhibition. The responses of soybean plants, in terms of daidzein and genistein synthesis and exudation, to different mineral N levels were studied. Daidzein and genistein distribution patterns varied with plant organs, mineral N levels, and plant development stages. Mineral N inhibited daidzein and genistein contents and concentrations in soybean root and shoot extracts, but did not affect root daidzein and genistein excretion in the same way. In both synthesis and excretion, daidzein and genistein were not affected equally by mineral N treatments. Variability existed among soybean cultivars in the responses of root daidzein and genistein contents and concentrations to mineral N levels. The amount of daidzein and genistein excreted by soybean roots did not always correspond to the daidzein and genistein contents and concentrations inside the roots. On the Bradyrhizobium japonicum side, nod gene expression was inhibited by mineral nitrogen. Genistein was used to pre-incubate B. japonicum cells or was applied directly into the plant growing medium. The results showed that genistein manipulation increased nodule weight and nodule nitrogen fixation under greenhouse conditions, but interactions existed among soybean cultivars, genistein concentrations and nitrate levels. Similar results were found under field conditions. Soybean yield was increased on sandy-loam soil by preincubation of B. japonicum cells with genistein. Addition of genistein beginning at the onset of nitrogen fixation also improved soybean nodulation and nitrogen fixation. Soybean cultivars had different sensitivities to genistein additiOther studies also show that temperature affected genistein and daidzein content and concentration in soybean roots. The effect of temperature varied among soybean cultivars. Some PGPR strains can mitigate the negative effects of nitrate on soybean nodulation and nitrogen fixation, however, this is influenced by soybean genotype. Applying PGPR together with genistein preincubation of B. japonicum cells improved soybean nodulation and increased yield. The level of improvement varied among soybean cultivars and PGPR strains. Preincubation of B. japonicum cells with genistein improved strain competitiveness under greenhouse, but not field conditions.Overall, these findings suggested that both plant-to-Bradyrhizobium and Bradyrhizobium-to-plant signals play important roles in the effects of mineral N on nodulation and N fixation. Signal manipulation could partially overcome the inhibitory effects of mineral N on soybean- B. japonicum N fixation symbiosis.McGill UniversitySmith, D. L. (advisor)1999Electronic Thesis or Dissertationapplication/pdfenalephsysno: 001746765proquestno: NQ64635Theses scanned by UMI/ProQuest.All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated.Doctor of Philosophy (Department of Plant Science.) http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=36670 |
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Soybean. Rhizobium japonicum. Nitrogen-fixing microorganisms. Plant cellular signal transduction. |
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Soybean. Rhizobium japonicum. Nitrogen-fixing microorganisms. Plant cellular signal transduction. Pan, Bo, 1963- Mineral nitrogen inhibition and signal production in soybean-B. japonicum symbiosis |
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In the N2 fixing legume symbiosis, mineral nitrogen (N) not only decreases N2 fixation, but also delays and inhibits the formation and development of nodules. The purposes of this thesis were to elucidate the role of signaling in the mineral N effects on nodulation and nitrogen fixation in soybean [Glycine max (L.) Merr.] and to attempt to find ways to overcome this inhibition. The responses of soybean plants, in terms of daidzein and genistein synthesis and exudation, to different mineral N levels were studied. Daidzein and genistein distribution patterns varied with plant organs, mineral N levels, and plant development stages. Mineral N inhibited daidzein and genistein contents and concentrations in soybean root and shoot extracts, but did not affect root daidzein and genistein excretion in the same way. In both synthesis and excretion, daidzein and genistein were not affected equally by mineral N treatments. Variability existed among soybean cultivars in the responses of root daidzein and genistein contents and concentrations to mineral N levels. The amount of daidzein and genistein excreted by soybean roots did not always correspond to the daidzein and genistein contents and concentrations inside the roots. On the Bradyrhizobium japonicum side, nod gene expression was inhibited by mineral nitrogen. Genistein was used to pre-incubate B. japonicum cells or was applied directly into the plant growing medium. The results showed that genistein manipulation increased nodule weight and nodule nitrogen fixation under greenhouse conditions, but interactions existed among soybean cultivars, genistein concentrations and nitrate levels. Similar results were found under field conditions. Soybean yield was increased on sandy-loam soil by preincubation of B. japonicum cells with genistein. Addition of genistein beginning at the onset of nitrogen fixation also improved soybean nodulation and nitrogen fixation. Soybean cultivars had different sensitivities to genistein additi === Other studies also show that temperature affected genistein and daidzein content and concentration in soybean roots. The effect of temperature varied among soybean cultivars. Some PGPR strains can mitigate the negative effects of nitrate on soybean nodulation and nitrogen fixation, however, this is influenced by soybean genotype. Applying PGPR together with genistein preincubation of B. japonicum cells improved soybean nodulation and increased yield. The level of improvement varied among soybean cultivars and PGPR strains. Preincubation of B. japonicum cells with genistein improved strain competitiveness under greenhouse, but not field conditions. === Overall, these findings suggested that both plant-to-Bradyrhizobium and Bradyrhizobium-to-plant signals play important roles in the effects of mineral N on nodulation and N fixation. Signal manipulation could partially overcome the inhibitory effects of mineral N on soybean- B. japonicum N fixation symbiosis. |
author2 |
Smith, D. L. (advisor) |
author_facet |
Smith, D. L. (advisor) Pan, Bo, 1963- |
author |
Pan, Bo, 1963- |
author_sort |
Pan, Bo, 1963- |
title |
Mineral nitrogen inhibition and signal production in soybean-B. japonicum symbiosis |
title_short |
Mineral nitrogen inhibition and signal production in soybean-B. japonicum symbiosis |
title_full |
Mineral nitrogen inhibition and signal production in soybean-B. japonicum symbiosis |
title_fullStr |
Mineral nitrogen inhibition and signal production in soybean-B. japonicum symbiosis |
title_full_unstemmed |
Mineral nitrogen inhibition and signal production in soybean-B. japonicum symbiosis |
title_sort |
mineral nitrogen inhibition and signal production in soybean-b. japonicum symbiosis |
publisher |
McGill University |
publishDate |
1999 |
url |
http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=36670 |
work_keys_str_mv |
AT panbo1963 mineralnitrogeninhibitionandsignalproductioninsoybeanbjaponicumsymbiosis AT panbo1963 isoflavonoidsandnitrogeninhibitioninsoybeanbjaponicumsymbiosis |
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1716637659373240320 |