The genetic analysis of Rhizobium in relation to symbiotic nitrogen fixation

Beringer, J. E.; Brewin, N. J.; Johnston, Andrew

doi:10.1038/hdy.1980.59

Cited by 76 publications

(38 citation statements)

References 105 publications

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“…(Vigna) 63 but it was very ineffi cient in Rhizobium leguminosarum bv. viciae 43 and R. leguminosarum bv. trifolii 21 .…”

Section: Isolation and Identifi Cation Of Auxotrophic Mutantsmentioning

confidence: 99%

Auxotrophy in rhizobia revisited

Yadav

2007

Indian J Microbiol

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Among the various types of mutations studied in rhizobia, the auxotrophic mutations (which confer on the mutants the inability to synthesize certain essential substances such as amino acids, vitamins and nucleic acids), are the most favoured ones as these can be used as suitable markers for genetic analysis. An important property of rhizobia is their effectiveness i.e. their ability to fi x atmospheric nitrogen into ammonia within the nodule. Special interest in this category of mutations by rhizobial geneticists is due to the fact that there is a strong correlation between the metabolic defects and the ineffectiveness (Nod -and/or Fix -) of the rhizobial strains. Auxotrophic mutants of various species of rhizobia with defects in the synthesis of nucleic bases, vitamins and amino acids have been obtained by mutagenising with physical, chemical and Tn5 mutagens. These mutants have been used in mapping studies as well as in establishing a correlation between its metabolic requirement and symbiotic relationship with the host plant. The present review deals with the isolation of auxotrophs, and their genetic, biochemical and symbiotic characterization. The review also encompasses the studies on the elucidation of biosynthetic pathways of nutritional substances in rhizobia.

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“…(Vigna) 63 but it was very ineffi cient in Rhizobium leguminosarum bv. viciae 43 and R. leguminosarum bv. trifolii 21 .…”

Section: Isolation and Identifi Cation Of Auxotrophic Mutantsmentioning

confidence: 99%

Auxotrophy in rhizobia revisited

Yadav

2007

Indian J Microbiol

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“…In some legume-Rhizobium associations, the host plant can supply the auxotrophic symbiont with the required nutrient(s) (Djordjevic et al, 1988). However, the success of this physiological complementation will depend on the host plant, the rhizobial strain, and the nature of the auxotrophy (Beringer et al, 1980). One intriguing type of finding is that in some biosynthetic pathways, intermediates, rather than endproducts, may be required for the bacteria to elicit nodule development or infection.…”

Section: Introductionmentioning

confidence: 99%

A purL mutant of Sinorhizobium fredii HH103 is symbiotically defective and altered in its lipopolysaccharide

et al. 2003

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The pleiotropic phenotype of an auxotrophic purL mutant (SVQ295) of Sinorhizobium fredii HH103 has been investigated. SVQ295 forms colonies that are translucent, produce more slime and absorb less Congo red than those of wild-type strain HH103. SVQ295 did not grow in minimal medium unless the culture was supplemented with thiamin and adenine or with thiamin and AICA-riboside (5-aminoimidazole-4-carboxamide 1-b-D-ribofuranoside), an intermediate of purine biosynthesis. Bacterial cultures supplemented with AICA-riboside or adenine reached the same culture density, although the doubling time of SVQ295 cultures containing AICA-riboside was clearly longer. S. fredii SVQ295 induced pseudonodules on Glycine max and failed to nodulate six different legumes. On Glycyrrhiza uralensis, however, nodules showing nitrogenase activity and containing infected plant cells were formed. SVQ295 showed auto-agglutination when grown in liquid TY medium and its lipopolysaccharide (LPS) electrophoretic profile differed from that of its parental strain HH103-1. In addition, four monoclonal antibodies that recognize the LPS of S. fredii HH103 failed to recognize the LPS produced by SVQ295. In contrast, 1 H-NMR spectra of K-antigen capsular polysaccharides (KPS) produced by SVQ295 and the wild-type strain HH103 were similar. Co-inoculation of soybean plants with SVQ295 and SVQ116 (a nodA mutant derivative of HH103) produced nitrogen-fixing nodules that were only occupied by SVQ116.

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“…with leguminous plants results in the formation of a highly specialized organ, the root nodule, which provides the appropriate biochemical environment for the reduction of dinitrogen. The formation and maintenance of the functional nodules depend on a coordinated expression of both plant and bacterial genes (for reviews, see Beringer et al, 1980;Verma and Long, 1983). Both genetic and biochemical evidence (Caldwell and Vest, 1977;Verma and Nadler, 1984) indicates that the host plant plays an important role in the nodulation process.…”

Section: Introductionmentioning

confidence: 99%