ABSTRACT
The biochemical environment of a rhizosphere system is composed of root exudations, and secretions from rhizobacteria, fungi and other soil organisms, arising from the dynamic interactions among plant roots, microbial organisms and other microfauna. These compounds directly or indirectly in§uence the microbial growth in the rhizosphere. In turn, the rhizosphere microbes serve as
CONTENTS
8.1 Introduction .......................................................................................................................... 173 8.2 Rhizosphere .......................................................................................................................... 174
8.2.1 Composition and Biochemistry of the Rhizosphere ................................................. 174 8.2.1.1 Root Exudates ............................................................................................ 174 8.2.1.2 Rhizobacteria ............................................................................................. 175 8.2.1.3 Soil Fungi ................................................................................................... 175 8.2.1.4 Soil Nematodes .......................................................................................... 175
8.2.2 Aquatic versus Soil Rhizosphere .............................................................................. 175 8.3 Rhizosphere Metabolomics .................................................................................................. 176
8.3.1 Analytical Techniques for Rhizosphere Metabolomics ............................................ 176 8.3.1.1 Chromatography Techniques ..................................................................... 176 8.3.1.2 MS Techniques........................................................................................... 177 8.3.1.3 Spectroscopy Techniques ........................................................................... 179
8.3.2 Metabolomics Data Handling and Analysis ............................................................. 180 8.4 Applications of Rhizosphere Metabolomics ......................................................................... 183
8.4.1 Rhizoremediation ..................................................................................................... 183 8.4.2 Sustainable Agriculture ............................................................................................ 183
8.5 Conclusion ............................................................................................................................ 184 Acknowledgements ........................................................................................................................ 184 References ...................................................................................................................................... 184
plant growth promoters or acts as pathogens inhibiting plant growth. Microbial degradation of natural or synthetic compounds (pesticides or plastics), nitrication by autotrophic bacteria or reactions of nitrate and sulphate also take place in the rhizosphere system. The rhizosphere metabolism is thus the result of complex interactions between micro§ora and microfauna yielding exudations, lysates, chelators, antibiotics, phytostimulators and extracellular enzymes, making it distinctive from the rest of the plant system. Hence, a systemic understanding of the rhizosphere biochemical environment is necessary to implement suitable biotechnological methods for sustainable agriculture.
