Nodulation of legumes

Bacteroid- Altered form of cells of certain bacteria. Refers particularly to the swollen, irregular vacuolated cells of rhizobia in nodules of legumes. 

J. L. Henriques-Saba, A. Squartini, and M. P. Nuti, Nodulation of legumes under alkaline conditions. The case of Hedysarum coronarium. 8" International Congress on Molecular Plant Microbe Interactions, Knoxville, TN, July 14-19, 1996. 

Aliphatic acids such as butyric acid have been previously implicated as being allelopathic compounds (46, 47, 23). Chou and Patrick (23) isolated butyric acid from soil amended with rye and showed that it was phytotoxic. Hydroxy acids have also been shown to possess phytotoxic properties (48) but have not been implicated in any allelopathic associations. Since SHBA is a stereo isomer, and the enantiomer was not identified because of impurity, all bioassays were run using a racemic mixture. The D-(-) stereo isomer of SHBA has been isolated from both microorganisms and root nodules of legumes and is suspected to be a metabolic intermediate in these systems (49). It is likely that only one enantiomer was present in the extract therefore, the true phytotoxic potential of this compound awaits clarification of the phytotoxicity of the individual enantiomers. 

Apart from minor sources such as thunderstorms (Section 9.2), atmospheric nitrogen is fixed in Nature by certain soil bacteria, blue-green algae, and microorganisms in the root nodules of legumes. This is accomplished either by oxidation to nitrate... 

The only reactions of molecular nitrogen at ambient temperature are the formation of lithium nitride Li3N, reactions with certain transition metal complexes, and nitrogen fixation with nitrogenase in the bacteria of the root nodules of legumes and in blue algae (Sections 14.1.1 and 14.1.2). Above 500 °C nitrogen reacts with some elements, especially with metals (nitride formation). 

Hemoglobins are the most evolutionarily diverse family of dioxygen carriers. They are found in some plants (e.g., leghemoglobin in the nitrogen-fixing nodules of legumes), many invertebrates (including some insect larvae), crustaceans, molluscs (especially bivalves and snails), almost all annelid worms, and in all vertebrates with one possible exception, the Antarctic fish Cyclostomata. 

Although many microorganisms are apparently capable of denitrification, only a few specialized species, including the free-living Azotobacter, blue-green algae, some anaerobic bacteria, and Rhizobium bacteria in root nodules of legumes, are ca-... 

Bergersen, F. J. Root Nodules of Legumes Structure and Functions Research Studies Press, John Wiley and Sons Ltd. London, 1982. 

Sutherland J M, Sprent J I 1984 Calcium-oxalate crystals and crystal cells in determinate root nodules of legumes. Planta 161 193-200... 

J. S. Pate, C. A. Atkins, and R. M. Rumbird, Theoretical and experimental costing of nitrogen fixation and related processes in nodules of legumes, in Current Perspectives in Nitrogen Fixation (A. H. Gibson and W. E. Newton, eds.), Australian Academy of Sciences, Canberra (1981). 

Pueppke, J.L., The genetics and biochemical basis for nodulation of legumes by rhyzobia, Crit. Rev. Biotechnol., 16, 1-51, 1996. 

Bacteria found in the root nodules of legumes also fix N2. An important area of current research is the search for catalysts that can mimic bacteria and fix nitrogen at ordinary temperatures. 

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