Nitrogen is an essential nutrient. As N2 gas it is a major constituent of the atmosphere, but N2 is chemically inert and therefore unavailable as a source of nitrogen for use by most living organisms. However, some bacteria have the ability to reduce N2 and thereby “fix” atmospheric nitrogen using the enzyme nitrogenase. Many leguminous plants have capitalised on this special bacterial asset by going into partnership with nitrogen-fixing bacteria called rhizobia. In return for supplying nutrients to the bacteria, the plants receive a supply of reduced nitrogen. In essence, the legumes create a highly specialised environment within which the bacteria fix nitrogen. These specialised plant structures are called nodules; usually they are found on roots, but they also occur on the stems of some legumes.
KeywordsNitrogen Fixation Root Hair Nodule Development Infection Thread Legume Root
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- 1.Bergersen FJ (1982) Root nodules of legumes: structure and functions. Research Studies Press, John Wiley and Sons, Chichester.Google Scholar
- Dart PJ (1977) Infection and development of leguminous root nodules. In: Hardy RWF, Silver WS (eds) A treatise on dinitrogen fixation, III, Biology. Wiley, New Nork, pp 367–472.Google Scholar
- 5.Carroll BJ, Mathews A (1990) Nitrate inhibition of nodulation in legumes. In: Gresshoff PM (ed) Molecular biology of symbiotic nitrogen fixation. CRC Press, Boca Raton, pp 159–180.Google Scholar
- Weeden NF, Kneen BE, LaRue TA (1990) Genetic analysis of sym genes and other related genes in Pisum sativum. In: Gresshoff PM, Roth J, Stacey G, Newton W (eds) Nitrogen fixation: achievements and objectives. Chapman and Hall, New York, pp 323–330.Google Scholar
- 8.Robertson JG, Wells B, Brewin NJ, Wood EA, Knight CD, Downie JA (1985) The legume-Rhizobium symbiosis: a cell surface interaction. J Cell Sci (Suppl) 2:317–331.Google Scholar
- 10.Verma DPS, Delauney AJ (1988) Root nodule symbiosis: Nodulins and nodulin genes. In: Verma DPS, Goldberg RB (eds) Plant gene research. Springer, Berlin Heidelberg New York, pp 169–199.Google Scholar
- Forde BG, Cullimore JV (1989) The molecular biology of glutamine synthetase in higher plants. Oxford Surv Plant Mol Cell Biol 6:247–296.Google Scholar
- Verma DPS, Long S (1983) The molecular biology of the Rhizobium-legume symbiosis. In: Jeon K (ed) International review of cytology. Academic Press, New Nork, pp 211–245 (Suppl 14).Google Scholar