Detection of loci in the leu region of Rhizobium meliloti chromosome

A multi-marked strain of Rhizobium meliloti was developed by the co-mutation method and employed to contribute to the genetic map of R. meliloti chromosome. Seven loci were placed at 5 sites in theleu region in the orderman-aba, fix, leu-cro-azt, ost-thi

Tn5 induced mutants of iron assimilation pathway in <i>Cicer Rhizobium </i>strain, COBE13

691-695Siderophore mutants provide an understanding of the iron assimilation pathway under iron limiting conditions. Random Tn5 insertion mutants with varying phenotypes were isolated in Cicer-Rhizobium strain COBE 13. Analysis on siderophore crossfeeding plate identified these mutants as defective in siderophore synthesis, uptake and utilization deficient in siderophore-Fe (III) complex and in regulation

Interaction of a mutator with a mutationally stable genetic system in Escherichia coli

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Characterization of intrinsic variability of <i style="">Mesorhizobium ciceri</i> isolates of cultivated fields

671-674A large number of putative rhizobial isolates were obtained from the root nodules of various chickpea cultivars growing in agricultural research fields. Of these, thirty were selected and characterized for traits, such as, generation time, intrinsic azide resistance and several symbiotic characters

Phenotypic and molecular characterization of indigenous rhizobia nodulating chickpea in India

340-350In a combined approach of phenotypic and genotypic characterization, 28 indigenous rhizobial isolates obtained from different chickpea growing regions in peninsular and northern India were analyzed for diversity. The field isolates were compared to two reference strains TAL620 and UPM-Ca142 representing M. ciceri and M. mediterraneum respectively. Phenotypic markers such as resistance to antibiotics, tolerance to salinity, temperature, pH, phosphate solubilization ability, growth rate and also symbiotic efficiency showed considerable diversity among rhizobial isolates. Their phenotypic patterns showed adaptations of rhizobial isolates to abiotic stresses such as heat and salinity. Two salt tolerant strains (1.5% NaCl by T1 and T4) with relatively high symbiotic efficiency and two P-solubilising strains (66.7 and 71 mg/ml by T2 and T5) were identified as potential bioinoculants. Molecular profiling by 16S ribosomal DNA Restriction Fragment Length Polymorphism (RFLP) revealed three clusters at 67% similarity level. Further, the isolates were differentiated at intraspecific level by 16S rRNA gene phylogeny. Results assigned all the chickpea rhizobial field isolates to belong to three different species of Mesorhizobium genus. 46% of the isolates grouped with Mesorhizobium loti and the rest were identified as M. ciceri and M. mediterraneum, the two species which have been formerly described as specific chickpea symbionts. This is the first report on characterization of chickpea nodulating rhizobia covering soils of both northern and peninsular India. The collection of isolates, diverse in terms of species and symbiotic effectiveness holds a vast pool of genetic material which can be effectively used to yield superior inoculant strains