Expression of<i>Rhizobium galegae</i>Common<i>nod</i>Clones in Various Backgrounds

La, Räsänen; Heikkilä-Kallio, U; Suominen, Leena; Lipsanen, Päivi; Lindström, Kristina

doi:10.1094/mpmi-4-535

Cited by 24 publications

(12 citation statements)

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“…viciae HAMBI 1594. These strains have previously been shown to induce root nodules on the hosts Medicago sativa ( A. fabrum and S. meliloti ) and Vicia villosa ( R. leguminosarum ) when complemented with a cosmid clone containing common nod genes of N. galegae HAMBI 1174 [58]. It is also not possible to exclude a scenario where donor cells were still present on the selective plate, so that conjugation may have taken place only at the inoculation stage, in the presence of the plant.…”

Section: Discussionmentioning

confidence: 99%

Genome sequencing of two Neorhizobium galegae strains reveals a noeT gene responsible for the unusual acetylation of the nodulation factors

et al. 2014

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BackgroundThe species Neorhizobium galegae comprises two symbiovars that induce nodules on Galega plants. Strains of both symbiovars, orientalis and officinalis, induce nodules on the same plant species, but fix nitrogen only in their own host species. The mechanism behind this strict host specificity is not yet known. In this study, genome sequences of representatives of the two symbiovars were produced, providing new material for studying properties of N. galegae, with a special interest in genomic differences that may play a role in host specificity.ResultsThe genome sequences confirmed that the two representative strains are much alike at a whole-genome level. Analysis of orthologous genes showed that N. galegae has a higher number of orthologs shared with Rhizobium than with Agrobacterium. The symbiosis plasmid of strain HAMBI 1141 was shown to transfer by conjugation under optimal conditions. In addition, both sequenced strains have an acetyltransferase gene which was shown to modify the Nod factor on the residue adjacent to the non-reducing-terminal residue. The working hypothesis that this gene is of major importance in directing host specificity of N. galegae could not, however, be confirmed.ConclusionsStrains of N. galegae have many genes differentiating them from strains of Agrobacterium, Rhizobium and Sinorhizobium. However, the mechanism behind their ecological difference is not evident. Although the final determinant for the strict host specificity of N. galegae remains to be identified, the gene responsible for the species-specific acetylation of the Nod factors was identified in this study. We propose the name noeT for this gene to reflect its role in symbiosis.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2164-15-500) contains supplementary material, which is available to authorized users.

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Section: Discussionmentioning

confidence: 99%

Genome sequencing of two Neorhizobium galegae strains reveals a noeT gene responsible for the unusual acetylation of the nodulation factors

et al. 2014

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“…Host specificity of the symbiotic interaction is manifested at two levels. Galega plant root exudate induces R. galegae strains in a very specific interaction with NodD1 (Räsänen et al 1991, Suominen et al 2003. The Nod factor produced by the bacteria in response to exudate induction carries a unique mixture of molecules with polyunsaturated fatty acyl chains and an acyl group on the penultimate chito-oligosaccharide residue (Yang et al 1999).…”

Section: Host Specificity and Effectivenessmentioning

confidence: 99%

Nitrogen-fixing bacteria associated with leguminous and non-leguminous plants

2008

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Nitrogen is generally considered one of the major limiting nutrients in plant growth. The biological process responsible for reduction of molecular nitrogen into ammonia is referred to as nitrogen fixation. A wide diversity of nitrogen-fixing bacterial species belonging to most phyla of the Bacteria domain have the capacity to colonize the rhizosphere and to interact with plants. Leguminous and actinorhizal plants can obtain their nitrogen by association with rhizobia or Frankia via differentiation on their respective host plants of a specialized organ, the root nodule. Other symbiotic associations involve heterocystous cyanobacteria, while increasing numbers of nitrogen-fixing species have been identified as colonizing the root surface and, in some cases, the root interior of a variety of cereal crops and pasture grasses. Basic and advanced aspects of these associations are covered in this review.

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“…Sinorhizobium cells infected A. senegal roots via infection threads, and thus the infection process resembled that between rhizobia and temperate herbaceous legumes. When comparing the infection process of A. senegal to for example Medicago sativa , Galega orientalis and Vicia villosa [26], the root hairs did not cover A. senegal roots continuously, deformed root hairs were generally short and infection threads occurred mostly in short root hairs. Methylene blue stained the whole root system light blue (Fig.…”

Section: Discussionmentioning

confidence: 98%

“…The plants were harvested after 6 weeks and scored for nodulation. Plant roots from one replicate jar were used for determination of GUS activity in the nodules, and plant roots from the other replicate jar were used for determination of nitrogenase activity by the acetylene reduction method [26]. To test the competitive ability of GUS‐marked isolates, duplicate jars containing three A. senegal seedlings were inoculated with 5 ml of suspension containing the parental strain 1552 and the GUS‐marked isolate in ratio 1:1.…”

Section: Methodsmentioning

confidence: 99%

The effect of heat stress on the symbiotic interaction between Sinorhizobium sp. and Acacia senegal

Rásänen¹,

Lindström²

1999

FEMS Microbiology Ecology

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Sinorhizobium sp. strain HAMBI 2180, marked with the β‐glucuronidase (GUS) encoding gusA gene, was used for studying the effect of heat stress on the symbiotic interaction between Acacia senegal seedlings and Sinorhizobium sp. in growth cabinet conditions. The infection process, observed during 18 days after inoculation, was delayed at a root temperature of 40°C compared to a root temperature of ≤38°C, but nodulation was retarded already at 38°C. At 42°C no nodules were formed. At this root temperature the development of lateral roots and root hairs was one week delayed. Although the roots had normally deformed root hairs in addition to abnormally deformed ones, only disintegrated infection threads were present. However, the ability to form symbiosis was reversible. Nitrogen‐fixing nodules developed on those parts of the roots which were formed after completion of the thermal stress at 42°C. A root temperature of 42°C did not affect the numbers of culturable rhizobia in the A. senegal rhizosphere.

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Expression ofRhizobium galegaeCommonnodClones in Various Backgrounds

Cited by 24 publications

References 0 publications

Genome sequencing of two Neorhizobium galegae strains reveals a noeT gene responsible for the unusual acetylation of the nodulation factors

Genome sequencing of two Neorhizobium galegae strains reveals a noeT gene responsible for the unusual acetylation of the nodulation factors

Nitrogen-fixing bacteria associated with leguminous and non-leguminous plants

The effect of heat stress on the symbiotic interaction between Sinorhizobium sp. and Acacia senegal

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