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Aqbal Singh - One of the best experts on this subject based on the ideXlab platform.
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Characterization of an rpoN mutant of Mesorhizobium Ciceri
Journal of Applied Microbiology, 2007Co-Authors: U.s. Gautam, Aqbal Singh, A. Jajoo, P. K. ChakrabarttyAbstract:Aims: To study the genetic basis of C4-dicarboxylate transport (Dct) in relation to symbiotic nitrogen fixation in Mesorhizobium Ciceri. Methods and Results: A Tn5-induced mutant strain (TL16) of M. Ciceri, unable to grow on C4-dicarboxylates, was isolated from the wild-type strain TAL 620. The mutant lacked activities of the enzymes, which use C4-dicarboxylates as substrate. The sequencing of the 3·2kb EcoRI fragment, which was the site of Tn5 insertion, revealed three complete and two partial open reading frames. In the mutant, Tn5 interrupted the rpoN gene, of which only one copy was there. Complementation and biochemical studies suggest that the M. Ciceri rpoN activity is required for C4-Dct, maturation of bacteroids and symbiotic nitrogen fixation. The fine structure of the ineffective nodules produced by TL16 on Cicer arietinum L changed in comparison with those produced by the wild type. Conclusions: The mutant strain TL16 suffered a disruption in the rpoN gene. Only one copy of rpoN gene is present in M. Ciceri. The mutation abolishes Dct activity. It additionally abolishes the symbiotic nitrogen fixation activity of the bacteroids in the nodules. Significance and Impact of the Study: This first document in M. Ciceri shows that a functional rpoN gene is essential for the transport of dicarboxylic acids and symbiotic nitrogen fixation.
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Characterization of a symbiotically defective serine auxotroph of Mesorhizobium Ciceri.
Fems Microbiology Letters, 2006Co-Authors: U.s. Gautam, P. K. Chakrabartty, Aqbal SinghAbstract:A Tn5-induced mutant strain (TL68) of Mesorhizobium Ciceri unable to grow with ammonium as the sole nitrogen source was isolated and characterized. Unlike its wild-type parent (strain TAL620), the mutant had an absolute dependence on serine to grow. Cloning of the DNA region containing Tn5 and sequence analysis showed that Tn5 was inserted into the gene coding for 3-phosphoglycerate dehydrogenase, which catalyses the first step in the serine biosynthetic pathway. The role of serine biosynthesis of M. Ciceri in the establishment of nitrogen-fixing symbiosis with chickpea ( Cicer arietinum L) was investigated using the mutant TL68. The serA − mutant (TL68) was unable to elicit the development of efficient nodules on the roots of Cicer arietinum L. The addition of serine to the plant-growth medium restored the ability of the mutant to nodulate Cicer arietinum , and the nodules were able to fix nitrogen.
U.s. Gautam - One of the best experts on this subject based on the ideXlab platform.
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Characterization of an rpoN mutant of Mesorhizobium Ciceri
Journal of Applied Microbiology, 2007Co-Authors: U.s. Gautam, Aqbal Singh, A. Jajoo, P. K. ChakrabarttyAbstract:Aims: To study the genetic basis of C4-dicarboxylate transport (Dct) in relation to symbiotic nitrogen fixation in Mesorhizobium Ciceri. Methods and Results: A Tn5-induced mutant strain (TL16) of M. Ciceri, unable to grow on C4-dicarboxylates, was isolated from the wild-type strain TAL 620. The mutant lacked activities of the enzymes, which use C4-dicarboxylates as substrate. The sequencing of the 3·2kb EcoRI fragment, which was the site of Tn5 insertion, revealed three complete and two partial open reading frames. In the mutant, Tn5 interrupted the rpoN gene, of which only one copy was there. Complementation and biochemical studies suggest that the M. Ciceri rpoN activity is required for C4-Dct, maturation of bacteroids and symbiotic nitrogen fixation. The fine structure of the ineffective nodules produced by TL16 on Cicer arietinum L changed in comparison with those produced by the wild type. Conclusions: The mutant strain TL16 suffered a disruption in the rpoN gene. Only one copy of rpoN gene is present in M. Ciceri. The mutation abolishes Dct activity. It additionally abolishes the symbiotic nitrogen fixation activity of the bacteroids in the nodules. Significance and Impact of the Study: This first document in M. Ciceri shows that a functional rpoN gene is essential for the transport of dicarboxylic acids and symbiotic nitrogen fixation.
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Characterization of a symbiotically defective serine auxotroph of Mesorhizobium Ciceri.
Fems Microbiology Letters, 2006Co-Authors: U.s. Gautam, P. K. Chakrabartty, Aqbal SinghAbstract:A Tn5-induced mutant strain (TL68) of Mesorhizobium Ciceri unable to grow with ammonium as the sole nitrogen source was isolated and characterized. Unlike its wild-type parent (strain TAL620), the mutant had an absolute dependence on serine to grow. Cloning of the DNA region containing Tn5 and sequence analysis showed that Tn5 was inserted into the gene coding for 3-phosphoglycerate dehydrogenase, which catalyses the first step in the serine biosynthetic pathway. The role of serine biosynthesis of M. Ciceri in the establishment of nitrogen-fixing symbiosis with chickpea ( Cicer arietinum L) was investigated using the mutant TL68. The serA − mutant (TL68) was unable to elicit the development of efficient nodules on the roots of Cicer arietinum L. The addition of serine to the plant-growth medium restored the ability of the mutant to nodulate Cicer arietinum , and the nodules were able to fix nitrogen.
P. K. Chakrabartty - One of the best experts on this subject based on the ideXlab platform.
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Characterization of an rpoN mutant of Mesorhizobium Ciceri
Journal of Applied Microbiology, 2007Co-Authors: U.s. Gautam, Aqbal Singh, A. Jajoo, P. K. ChakrabarttyAbstract:Aims: To study the genetic basis of C4-dicarboxylate transport (Dct) in relation to symbiotic nitrogen fixation in Mesorhizobium Ciceri. Methods and Results: A Tn5-induced mutant strain (TL16) of M. Ciceri, unable to grow on C4-dicarboxylates, was isolated from the wild-type strain TAL 620. The mutant lacked activities of the enzymes, which use C4-dicarboxylates as substrate. The sequencing of the 3·2kb EcoRI fragment, which was the site of Tn5 insertion, revealed three complete and two partial open reading frames. In the mutant, Tn5 interrupted the rpoN gene, of which only one copy was there. Complementation and biochemical studies suggest that the M. Ciceri rpoN activity is required for C4-Dct, maturation of bacteroids and symbiotic nitrogen fixation. The fine structure of the ineffective nodules produced by TL16 on Cicer arietinum L changed in comparison with those produced by the wild type. Conclusions: The mutant strain TL16 suffered a disruption in the rpoN gene. Only one copy of rpoN gene is present in M. Ciceri. The mutation abolishes Dct activity. It additionally abolishes the symbiotic nitrogen fixation activity of the bacteroids in the nodules. Significance and Impact of the Study: This first document in M. Ciceri shows that a functional rpoN gene is essential for the transport of dicarboxylic acids and symbiotic nitrogen fixation.
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Characterization of a symbiotically defective serine auxotroph of Mesorhizobium Ciceri.
Fems Microbiology Letters, 2006Co-Authors: U.s. Gautam, P. K. Chakrabartty, Aqbal SinghAbstract:A Tn5-induced mutant strain (TL68) of Mesorhizobium Ciceri unable to grow with ammonium as the sole nitrogen source was isolated and characterized. Unlike its wild-type parent (strain TAL620), the mutant had an absolute dependence on serine to grow. Cloning of the DNA region containing Tn5 and sequence analysis showed that Tn5 was inserted into the gene coding for 3-phosphoglycerate dehydrogenase, which catalyses the first step in the serine biosynthetic pathway. The role of serine biosynthesis of M. Ciceri in the establishment of nitrogen-fixing symbiosis with chickpea ( Cicer arietinum L) was investigated using the mutant TL68. The serA − mutant (TL68) was unable to elicit the development of efficient nodules on the roots of Cicer arietinum L. The addition of serine to the plant-growth medium restored the ability of the mutant to nodulate Cicer arietinum , and the nodules were able to fix nitrogen.
Fred J. Muehlbauer - One of the best experts on this subject based on the ideXlab platform.
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Chickpea Hybridization Using In Vitro Techniques
Methods in molecular biology (Clifton N.J.), 2010Co-Authors: Nalini Mallikarjuna, Fred J. MuehlbauerAbstract:Tissue culture techniques play an important role in the utilization of wild Cicer species for the improvement of cultivated chickpea. Utilization of wild Cicer species has become essential as a series of evolutionary bottlenecks have narrowed the genetic base of chickpea, thus making it susceptible to a range of diseases and pests. Crosses with wild Cicer can broaden its genetic base and introduce useful traits. Except for two wild species, none of the other Cicer species are cross-compatible. To use a range of Cicer species for the improvement of chickpea, embryo rescue and tissue culture techniques are necessary. The success of the cross with incompatible species depended on a range of techniques including the application of growth regulators to pollinated pistils and saving aborting embryos in vitro. Further, the chances of successful transfer of hybrid shoots to soil are greater if the hybrid shoots are grafted to chickpea stocks
C.shekhar Nautiyal - One of the best experts on this subject based on the ideXlab platform.
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Rhizosphere competence of Pseudomonas sp. NBRI9926 and Rhizobium sp. NBRI9513 involved in the suppression of chickpea (Cicer arietinum L.) pathogenic fungi
FEMS Microbiology Ecology, 2006Co-Authors: C.shekhar NautiyalAbstract:In order to obtain chickpea (Cicer arietinum L.) rhizosphere-competent bacteria, 256 bacterial strains, representing different morphological types, were screened for their biocontrol activity against Fusarium oxysporum f.sp. Ciceri, Rhizoctonia bataticola and Pythium sp. under in vitro conditions. Pseudomonas sp. NBRI9926 and Rhizobium sp. NBRI9513 were selected for further work because of their unique ability to inhibit all three fungi. Spontaneous rifampicin-resistant (Rifr) derivatives of Pseudomonas sp. NBRI9926 and Rhizobium sp. NBRI9513 showing a growth rate and membrane protein composition comparable to the wild-type were selected to elucidate their rhizosphere competence on chickpea. Both strains showed no difference to their corresponding wild-type strains in terms of chickpea rhizosphere competence. However, when Pseudomonas sp. NBRI9926P3 was mixed in an equal or lower ratio with Rhizobium sp. NBRI9513R7, both in sterile soil and non-sterile soil assays, Rhizobium sp. NBRI9513R7 consistently failed to achieve titres similar to Pseudomonas sp. NBRI9926P3. These results suggest that antibiotic resistance-marked strains should be compared with wild-type parents before being used as monitors of parental strain survival. Pseudomonas sp. NBRI9926P3 was a better chickpea rhizosphere coloniser compared to Rhizobium sp. NBRI9513R7. Greenhouse results demonstrated a superior biocontrol potential of Pseudomonas sp. NBRI9926P3 to control F.oxysporum f.sp. Ciceri, R.bataticola and Pythium sp. compared to Rhizobium sp. NBRI9513R7. The screening method should prove useful in identifying rhizosphere bacteria with the greatest potential for controlling diseases caused by phytopathogenic fungi.
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Survival of the rhizosphere-competent biocontrol strain Pseudomonas fluorescens NBRI2650 in the soil and phytosphere.
Canadian journal of microbiology, 2002Co-Authors: C.shekhar Nautiyal, Jayandra Kumar Johri, H B SinghAbstract:Pseudomonas fluorescens NBRI2650 was isolated after screening 360 bacterial strains from the rhizosphere of chickpea (Cicer arietinum L.) grown in fungal-disease-suppressive field soil. The strain was selected because of its high rhizosphere competence and ability to inhibit the growth of Fusarium oxysporum f.sp. Ciceri, Rhizoctonia bataticola, and Pythium sp. under in vitro conditions. Survival and colonization of NBRI2650 in the phytosphere of chickpea, cotton (Gossypium hirsutum L.), cucumber (Cucumis sativus L.), and tomato (Lycopersicon seculentum Mill.) were monitored using a chromosomally located rifampicin-marked mutant P. fluorescens NBRI2650R. The strain showed variable ability to invade and survive in the phytosphere of different plants. Chickpea was used as a tester plant for further work, as it was not invaded by NBRI2650R. The interaction between NBRI2650R and F. oxysporum f.sp. Ciceri was studied by both light microscopy and scanning electron microscopy. The lysis of the fungal cell wall by...
