This book is the self-contained final volume of a comprehensive seven-volume series covering the basic and applied science relating to nitrogen fixation. It addresses the most important nitrogen-fixing symbiosis of all - that between legumes and their root-nodule bacteria - and therefore deals with the properties and behaviour of both macro- and micro-symbiont. The coverage is comprehensive, beginning with the extent of the symbiosis and how it may have arisen in the geological past. It considers how legumes select the root-nodule bacteria they allow to form nodules on their roots and the intricate series of signals to be exchanged between legume and bacteria for infection to occur. The immense progress in understanding the genetic systems in the bacteria necessary for nodulation is now being replicated in a rapidly increasing understanding of the required systems in the legumes. The cell biology of the processes of both infection and nodule development is analysed and leads to a parallel assessment of the biochemical processes in carbon and nitrogen metabolism required for successful nitroogen fixation by the symbiotic bacteroid. Attention is given to the ways in which the nodule has solved the conundrum of providing enough O2 for energy generation to drive nitrogen fixation without either inactivating the O2-sensitive nitrogenase or creating damaging reactive oxygen species. This volume also covers the basic physiology of the variety of root-nodule bacteria infecting legumes, as well as looking at the renewed controversy about the chemical form(s) of nitrogen exported to the legume. Successful exploitation of the legume symbiosis in agriculture, horticulture, and forestry demands an understanding of the ecology of the root-nodule bacteria - particularly what makes for a successful inoculant strain for legume introduction to agricultural systems. Then, there is a requirement for inoculation technology to both successfully deliverviable bacteria to the root surface and facilitate nodulation. These practical aspects are thoroughly covered in this volume, with a final chapter assessing how the massive amount of recent information can be exploited in matching host and microsymbiont for the wide variety of environments in which they are needed in our production systems.

Klappentext

This book is the self-contained final volume of a comprehensive seven-volume series covering the basic and applied science relating to nitrogen fixation. It addresses the most important nitrogen-fixing symbiosis of all that between legumes and their root-nodule bacteria and therefore deals with the properties and behaviour of both macro- and micro-symbiont. The coverage is comprehensive, beginning with the extent of the symbiosis and how it may have arisen in the geological past. It considers how legumes select the root-nodule bacteria they allow to form nodules on their roots and the intricate series of signals to be exchanged between legume and bacteria for infection to occur. The immense progress in understanding the genetic systems in the bacteria necessary for nodulation is now being replicated in a rapidly increasing understanding of the required systems in the legumes. The cell biology of the processes of both infection and nodule development is analysed and leads to a parallel assessment of the biochemical processes in carbon and nitrogen metabolism required for successful nitroogen fixation by the symbiotic bacteroid. Attention is given to the ways in which the nodule has solved the conundrum of providing enough O2 for energy generation to drive nitrogen fixation without either inactivating the O2-sensitive nitrogenase or creating damaging reactive oxygen species. This volume also covers the basic physiology of the variety of root-nodule bacteria infecting legumes, as well as looking at the renewed controversy about the chemical form(s) of nitrogen exported to the legume. Successful exploitation of the legume symbiosis in agriculture, horticulture, and forestry demands an understanding of the ecology of the root-nodule bacteria particularly what makes for a successful inoculant strain for legume introduction to agricultural systems. Then, there is a requirement for inoculation technology to both successfully deliverviable bacteria to the root surface and facilitate nodulation. These practical aspects are thoroughly covered in this volume, with a final chapter assessing how the massive amount of recent information can be exploited in matching host and microsymbiont for the wide variety of environments in which they are needed in our production systems.

Zusammenfassung

Nodules produced on legume roots by root-nodule bacteria provide the major nitrogenous input into natural and agricultural systems worldwide. This book provides an in-depth and up-to-the minute analysis of what is known about this symbiosis, its origins, the process of nodule formation and development, and the biochemistry and genetics of nodular nitrogen fixation. It also reviews the physiology of the root-nodule bacteria themselves, their ecology in both natural and agricultural systems, and how we go about introducing new legumes and the bactria they require. How all the knowledge gained about this system can be applied in the future for better legume-rhizobia functioning in difficult environments is its logical culmination.

Inhalt

Preface to the Series, Preface, List of Contributors, Dedication

1. Evolution and Diversity of Legume Symbiosis: J. I. Sprent
1. Introduction

2. The Diversity of Legume Nodules
3. The First 700 Million Years
4. The Last 60 Million Years
5. The Present

6. Conclusions
   References

   2. Ecology of Root-nodule Bacteria of Legumes:
   P. H. Graham

7. Introduction
8. Taxonomy of Root-nodule Bacteria
9. Population Structure of Rhizobia in Soil and Rhizosphere
10. Above and Below Ground Diversity and Symbiotic Function
11. Strain Competitiveness, Rhizosphere Colonization, and Persistence
12. Edaphic Factors Affecting Rhizobia

13. Future Dimensions of Rhizobial Ecology
    References

    3. Maintaining Cooperation in the Legume-Rhizobia Symbiosis: Identifying Selection Pressures and Mechanisms:
    E. T. Kiers, S. A. West and R. F. Denison

14. Introduction
15. Explaining Cooperation: The Problem
16. Explaining Cooperation: The Hypothesis
17. Cheating and Mixed Nodules
18. Future Directions

19. Conclusions
    Acknowledgements
    References

    4. Inoculation Technology for Legumes:
    D. F. Herridge

20. Introduction
21. The Need to Inoculate
22. Selection of Rhizobial Strains for Use in Inoculants
23. Inoculants in the Market Place
24. Pre-inoculated and Custom-inoculated Seed
25. Co-inoculation of Legumes with Rhizobia and Other Beneficial Microorganisms
26. Quality Control of Legume Inoculants
27. Constraints to Inoculant Use and Future Prospects

28. Concluding Statements
    References

    5. Fine-tuning of Symbiotic Genes in Rhizobia: Flavonoid Signal Transduction Cascade:
    H. Kobayashi and W. J. Broughton

29. Introduction
30. NODD and NOD-boxes: Central Elements in Transduction of Flanovoid Signals
31. Functions of Genes Controlled by NOD-boxes4. Fine-tuning Expression of Symbiotic Genes in Restricted Host-Range Rhizobia
32. Post-genomic Studies: Do Flavonoids Regulate Other Genes?

33. Conclusion and Perspectives: Roles of Flavonoid-inducible Regulons in Symbiosis, Signaling, and Adaptation
    References

    6. Cell Biology of Nodule Infection and Development:
    N. Maunoury, A. Kondorosi, E. Kondorosi and P. Mergaert
    1. Introduction

34. Nod-factor Signalling
35. Cortical-cell Activation Leading to Primordium Formation and Infection
36. Secondary Signals for Nod Factor-induced Cell Activation
37. Differentiation of N2-fixing Cells: The Role of Endoreduplication
38. Bacteroid Differentiation
39. Nitrogen Fixation

40. Senescence of Nodules
    References

    **7. Gene…