Grain legume crops, e.g. common bean (Phaseolus vulgaris L.), and soyabeans (Glycine max L.) are amongst the main sources of protein in Africa, Asia and Latin America. Their high protein content derive from their ability, in symbiosis with Rhizobium bacteria, to fix atmospheric nitrogen. Incorporating contributions from molecular biologists, microbiologists, plant breeders and soil scientists, this volume reports the results of an FAO/IAEA Co-ordinated Research Programme (1992-1996), whose main objective was to develop molecular biological methods to study rhizobial ecology. Use of better tracking methods will help enhance biological nitrogen fixation and thus grain legume yields, while reducing their reliance on soil- and/or fertilizer-nitrogen. This volume will be invaluable to scientists working on biological nitrogen fixation, soil microbial ecology and legume production.

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*2. rRNA based identification and detection systems for rhizobia and other bacteria.- *3. Rapid identification of Rhizobium strains by targeted PCR fingerprinting.- *4. Use of marker genes in competition studies of Rhizobium.- *5. Isolation of unique nucleic acid sequences from rhizobia by genomic subtraction: Applications in microbial ecology and symbiotic gene analysis.- *6. Potential of Rhizobium and Bradyrhizobium species as plant growth promoting rhizobacteria on non-legumes: Effect on radishes (Raphanus sativus L.).- *7. Competition in Kenyan soils between Rhizobiumleguminosarum biovar phaseoli strain Kim5 and R. tropici strain CIAT899 using the gusA marker gene.- *8. Effects of host plant origin on nodulin activities and nitrogen fixation in Phaseolus vulgaris L..- *9. Symbiotic performance of some modified Rhizobiumetli strains in assays with Phaseolusvulgaris beans that have a high capacity to fix N2.- * 10. Improvement of biological nitrogen fixation in Egyptian winter legumes through better management of Rhizobium.- *11. Analysis of PhaseolusRhizobium interactions in a subsistence farming system.- *12. Contributions and limitations to symbiotic nitrogen fixation in common bean (Phaseolus vulgaris L.) in Romania.- *13. Detection of Bradyrhizobium spp. and B. japonicum in Thailand by primer-based technology and direct DNA extraction.- *14. QTL mapping for nodule number and common bacterial blight in Phaseolusvulgaris L..- *15. Nitrogen fixation and nodule occupancy by native strains of Rhizobium on different cultivars of common bean (Phaseolus vulgaris L.).- 16. Use of rep-PCR to fingerprint the genome of Azospirillum spp..- 17. FAO/IAEA co-ordinated research programme on enhancement of nitrogen fixation in leguminous crops.