Symbiosis between the root-nodule bacterium Sinorhizobium meliloti and alfalfa (Medicago sativa) under salinization conditions

Ibragimova, M. V.; Rumyantseva, M. L.; Онищук, О. П.; Belova, V. S.; Курчак, О. Н.; Andronov, E. E.; Dzyubenko, N. I.; Симаров, Б. В.

doi:10.1134/s0026261706010140

Cited by 27 publications

(19 citation statements)

References 9 publications

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“…In the last two decades, extensive research has been conducted to understand the biochemistry and genetics of nitrogenfixing bacteria and their symbiosis with leguminous plants, given the importance of this process for sustainable agriculture (Cowie et al, 2006;Galibert et al, 2001;MacLean et al, 2007;Weidner et al, 2003). Soil bacteria encounter numerous adverse conditions in the environment, including increased soil salinity, acidic pH conditions and limited inorganic phosphate (P i ) (Cheng et al, 2005;Garau et al, 2005;Ibragimova et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

Cyclopropane fatty acyl synthase in Sinorhizobium meliloti

et al. 2009

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Cyclopropane fatty acyl synthases (CFA synthases) are enzymes that catalyse the addition of a methylene group across cis double bonds of monounsaturated fatty acyl chains in lipids. We have investigated the function of two putative genes, cfa1 and cfa2, proposed to code for CFA synthases in Sinorhizobium meliloti. Total fatty acid composition and fatty acid distributions within lipid classes for wild-type and cfa1 and cfa2 mutant strains grown under P i starvation and in acidic culture conditions were obtained by GC/MS and by infusion ESI/MS/MS, respectively. For wildtype cells and the cfa1 mutant, total cyclopropane fatty acids (CFAs) increased by 10 % and 15 % under P i starvation and acidic conditions, respectively; whereas in the cfa2 mutant, CFAs were less than 0.1 % of wild-type under both growth conditions. Reporter gene fusion experiments revealed that cfa1 and cfa2 were expressed at similar levels in free-living cells. Thus under the conditions we examined, cfa2 was required for the cyclopropanation of lipids in S. meliloti whereas the role of cfa1 remains to be determined. Analysis of intact lipids revealed that cyclopropanation occurred on cis-11-octadecenoic acid located in either the sn-1 or the sn-2 position in phospholipids and that cyclopropanation in the sn-2 position occurred to a greater extent in phosphatidylcholines and sulfoquinovosyldiacylglycerols under acidic conditions than under P i starvation. The cfa2 gene was also required for cyclopropanation of non-phosphoruscontaining lipids. Principal components analysis revealed no differences in the cyclopropanation of four lipid classes. We concluded that cyclopropanation occurred independently of the polar head group. Neither cfa1 nor cfa2 was required for symbiotic nitrogen fixation.

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Section: Introductionmentioning

confidence: 99%

Cyclopropane fatty acyl synthase in Sinorhizobium meliloti

et al. 2009

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“…The sequence of the S. meliloti AK21 genome has not yet been published, albeit Eckhardt lysis analysis revealed the presence of four replicons, three large ones probably corresponding to the chromosome, pSymA and pSymB, and a 120 kb-length plasmid (Ibragimova et al 2006; M. Bazzicalupo personal communication). It is known that other sequenced strains of S. meliloti present a genomic organization similar to Rm1021 (Galardini et al 2011) which was annotated with 6,292 genes distributed in the three replicons: 3,429 genes in the chromosome; 1,293 genes in pSymA; and 1,570 genes in pSymB (Galibert et al 2001).…”

Section: Resultsmentioning

confidence: 99%

“…However, the production and application of fertilizers are costly practices, both economically and ecologically. This led to efforts to isolate salt-tolerant plants and rhizobial strains mediating efficient nodulation in saline conditions, which have met with limited success (Ibragimova et al 2006; Moawad and Beck 1991; Craig et al 1991; Mohammad et al 1991; Chien et al 1992; Zou et al 1995; El-Sheikh and Wood 1995; Lal and Khanna 1995; Mashhady et al 1998; Hashem et al 1998; Ohwada et al 1998). In recent years, the emphasis has shifted to the description of genes conferring salt tolerance in free-living rhizobia and in rhizobia living in symbiosis with plants (Nogales et al 2002; Kanesaki et al 2002; Wei et al 2004; Han et al 2005; Domínguez-Ferreras et al 2006, 2009).…”

Section: Introductionmentioning

confidence: 99%

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Genomic characterization of Sinorhizobium meliloti AK21, a wild isolate from the Aral Sea Region

et al. 2015

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The symbiotic, nitrogen-fixing bacterium Sinorhizobium meliloti has been widely studied due to its ability to improve crop yields through direct interactions with leguminous plants. S. meliloti AK21 is a wild type strain that forms nodules on Medicago plants in saline and drought conditions in the Aral Sea Region. The aim of this work was to establish the genetic similarities and differences between S. meliloti AK21 and the reference strain S. meliloti 1021. Comparative genome hybridization with the model reference strain S. meliloti 1021 yielded 365 variable genes, grouped into 11 regions in the three main replicons in S. meliloti AK21. The most extensive regions of variability were found in the symbiotic plasmid pSymA, which also contained the largest number of orthologous and polymorphic sequences identified by suppression subtractive hybridization. This procedure identified a large number of divergent sequences and others without homology in the databases, the further investigation of which could provide new insight into the alternative metabolic pathways present in S. meliloti AK21. We identified a plasmid replication module from the repABC replicon family, together with plasmid mobilization-related genes (traG and a VirB9-like protein), which suggest that this indigenous isolate harbors an accessory plasmid. Furthermore, the transcriptomic profiles reflected differences in gene content and regulation between S. meliloti AK21 and S. meliloti 1021 (ExpR and PhoB regulons), but provided evidence for an as yet unknown, alternative mechanism involving activation of the cbb3 terminal oxidase. Finally, phenotypic microarrays characterization revealed a greater versatility of substrate use and chemical degradation than for S. meliloti 1021.Electronic supplementary materialThe online version of this article (doi:10.1186/s40064-015-1062-z) contains supplementary material, which is available to authorized users.

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“…Therefore, we analyzed the SE of the mutants using other varieties of alfalfa-Salt tolerant and Agnia under standard con ditions and with 0.6% NaCl modeling salt stress for alfalfa rhizobia (Ibragimova et al, 2006). The results of these experiments demonstrated ( Table 2) that for these varieties of alfalfa, the mutants had lower SE val ues than the parent strain under control conditions.…”

Section: Influence Of Host Plant Genotype and Salt Stress On The Se Omentioning

confidence: 99%

Identification of new genes of nodule bacteria Sinorhizobium meliloti involved in the control of efficiency of symbiosis with alfalfa Medicago sativa

Онищук

Chizhevskaya

Курчак

et al. 2015

Russ J Genet Appl Res

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Using a Tn5 mutagenesis in a Sinorhizobium meliloti strain CXM 1 105, we obtained three mutants with increased symbiotic efficiency with alfalfa. Our study demonstrated Tn5 insertions labeled two chromo some genes encoding 5 adenosylhomocysteine methylthioadenosine deaminase (mutant T4) and a protein belonging to the GntR family of transcription regulators (mutant M3) and a thiamine biosynthetic gene thiC, localized at megaplasmide 2 (mutant T795). Mutant T795 along with high symbiotic efficiency exhibited a reduced ability to compete for nodulation with the parent strain CXM1 105.

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Symbiosis between the root-nodule bacterium Sinorhizobium meliloti and alfalfa (Medicago sativa) under salinization conditions

Cited by 27 publications

References 9 publications

Cyclopropane fatty acyl synthase in Sinorhizobium meliloti

Cyclopropane fatty acyl synthase in Sinorhizobium meliloti

Genomic characterization of Sinorhizobium meliloti AK21, a wild isolate from the Aral Sea Region

Identification of new genes of nodule bacteria Sinorhizobium meliloti involved in the control of efficiency of symbiosis with alfalfa Medicago sativa

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