Genetic resources for improving nitrogen fixation in legume-rhizobia symbiosis

Provorov, N.A. and Tikhonovich, I.A. (2003) Genetic resources for improving nitrogen fixation in legume-rhizobia symbiosis. Genetic Resources and Crop Evolution, 50 (1). pp. 89-99.

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Leguminous crops are genetically polymorphous for the balance between symbiotrophic and combined types of nitrogen nutrition. In pea, polebean, alfalfa and fenugreek the wild-growing populations and local varieties exceed the agronomically advanced cultivars in the activity of N2 fixation that occurs in symbiosis with nodule bacteria (rhizobia). Combined nitrogen nutrition ensures higher productivity than symbiotrophic one in the “old” leguminous crops (pea, alfalfa, common vetch, polebean, soybean), while the symbiotrophic type dominates in some “young” crops (hairy vetch, kura clover, goat's rue). An importance is emphasized of using the symbiotically active wild-growing genotypes as the initial material for breeding the legume cultivars. The data on high heritability (broad sense, narrow sense, realized) of the legume symbiotic activity demonstrate that the plant selection for this activity may be highly effective. A range of methods to select the legumes for an improved symbiotic activity is available including plant growth in N-depleted substrates, analysis of nodulation scores, direct (“isotopic”) and indirect (acetylene reduction) estimation of nitrogenase activity. Analysis of the specificity of interactions between different plant genotypes and bacterial strains (via two-factor analysis of variance) demonstrates the strain-specific plant polygenes are of a special importance in controlling the intensity of nitrogen fixation. Therefore, a coordinated plant-bacteria breeding is required to create the optimal combinations of partners' genotypes. Selection and genetic construction of the commercially attractive rhizobia strains should involve improvement of nitrogen fixing, nodulation and competitive abilities expressed in combination with the symbiotically active plant genotypes, Breeding of the leguminous crops for the preferential nodulation by highly active rhizobia strains, for the ability to support N2 fixation under moderate N fertilization levels and to ensure a sufficient energy supply of symbiotrophic nitrogen nutrition is required

Item Type: Article
Additional Information: The research described in this publication was made possible in part by Award No. ST-012-0 of the U. S. Civilian Research & Development Foundation for the Independent States of the Former Soviet Union (CRDF).
Uncontrolled Keywords: Genetic resources, Leguminous crops, Nitrogen fixation, Nodulation, Plant breeding, Symbiosis
Author Affiliation: All-Russia Research Institute for Agricultural Microbiology, Russia
Subjects: Crop Improvement
Divisions: General
Depositing User: Mr Arbind Seth
Date Deposited: 19 Feb 2013 14:39
Last Modified: 19 Feb 2013 14:39
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