Nitrogen-fixing nodules induced by Agrobacterium tumefaciens harboring Rhizobium phaseoli plasmids

Martínez, Esperanza; Palacios, Rafael; Sánchez, Federico

doi:10.1128/jb.169.6.2828-2834.1987

Cited by 122 publications

(73 citation statements)

References 31 publications

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“…Nitrogen yield of the plants was also increased up to 67%, when inoculated with the transconjugants rhizobial strains as compared with the un-inoculated controls. These are in agreement with Martinez et al (1987), who found that genetic transfer between Rhizobium species has led to increase nodulation and nodule fresh and dry weight in legumes along with increase the growth and development of host plant. Similarly Truchet et al (1991) illustrated that trans-conjugants resulted from di-parental mating showed significant increase above the mid-parents in nodule number and dry weight of shoot.…”

Section: Discussionsupporting

confidence: 80%

Development of promiscous rhizobia for diverse rabi legumes (Chickpea, Pea and Lentil)

Ikbal

Jangra

Sarim

et al. 2017

JANS

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Conjugation between microsymbiont was used to create genetic variations in rhizobia for diverse rabi legumes (chickpea, pea and lentil) with better characteristics in nodulation and nitrogen fixation process. Ten antibiotics were used as selectable markers for the screening of twenty four bacterial strains to be used in mating experiments for obtaining transconjugants. All bacterial strains were sensitive to gentamycin and resistant to streptomycin, kanamycin and sulphanilamide. Total five fusants were obtained from each rhizobial cross combination with the help of electro-poration. Modified transconjugants, rhizobial strains had promiscuous infection with 50-122% more nodules showed significant increase in shoot fresh weight, dry weight and total nitrogen content in chickpea, pea and lentil plants. Electrofusants rhizobial strains improved shoot nitrogen content up to 67% in lentil and 54% in pea and chickpea plants. The amount of nitrogen fixed in chickpea was highest (3.71gm) by transconjugants DP-C6-HLN followed by DP-C6-HP14 (3.56gm). Transconjugants DP-HP14-HLN fixed the highest amount of nitrogen (3.92gm) in pea and 4.06gm in lentil plants. Plasmids were also analyzed in order to characterize their role in the evolution of rhizobial symbionts and their involvement in symbiotic behaviour. The developed Rhizobium strains with improved symbiotic association and ability to infect across strict specificity for host legumes would be of great help for the farming community at large.

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Section: Discussionsupporting

confidence: 80%

Development of promiscous rhizobia for diverse rabi legumes (Chickpea, Pea and Lentil)

Ikbal

Jangra

Sarim

et al. 2017

JANS

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“…In contrast, R. leguminosarum bv. phaseoli type II strains have a broad host range and single nitrogenase genes (5,29). The symbiotic plasmid analyzed is a complex structure containing a large amount of reiterated DNA sequences within the plasmid and with other regions of the genome as well, especially in other plasmids.…”

Section: Resultsmentioning

confidence: 99%

Structural complexity of the symbiotic plasmid of Rhizobium leguminosarum bv. phaseoli

et al. 1991

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The complete physical map of the symbiotic plasmid of Rhizobium leguminosarum bv. phaseoli strain CFN42 was established. The data support the concept that Rhizobium symbiotic genes are part of a complex genomic structure which contains a large amount of reiterated DNA sequences. This plasmid is a circular structure of 390 kb with approximately 10 families of internally reiterated DNA sequences of two to three elements each. One family includes two directly oriented nitrogenase operons situated 120 kb apart. We also found several stretches of pSym that are reiterated in other replicons of the cell. Localization of symbiotic gene sequences by heterologous hybridization revealed that nodABC sequences are separated in two regions, each of which contains a nod boxlike element, and it also suggested the presence of two copies of the nifA and nodD gene sequences. We propose that the complex structure of the symbiotic plasmid allows interactions between repeated DNA sequences which, in turn, might result in frequent rearrangements.Bacteria of the genus Rhizobium interact with the roots of leguminous plants to develop a highly specialized structure, the nitrogen-fixing nodule. Many genetic determinants of the symbionts are responsible for this differentiation process. The Rhizobium genome is organized in two different types of replicons, the chromosome and large plasmids. Usually, the genes involved in nodulation and nitrogen fixation processes are located on a single large plasmid. This plasmid is referred to as the symbiotic plasmid (pSym) (22,34,46).A general characteristic of the Rhizobium genome is the presence of a large number of reiterated DNA sequences (15,31,40). It has been established that genomic rearrangements in Rhizobium leguminosarum bv. phaseoli, the symbiont of the common bean plant, Phaseolus vulgaris, occur at high frequency (16,31). DNA rearrangements caused by recombination between repeated sequences might participate in the generation of genomic diversity.Establishment of the physical structure of the Rhizobium genome, in particular, the locations and orientations of reiterated DNA sequences, is of primary importance in elucidating the molecular mechanisms involved in genomic dynamics.As a model structure, we selected pSym of R. leguminosarum bv. phaseoli. Several physical maps of symbiotic regions of different Rhizobium species have been published, including large portions of the R. meliloti and Sinorhizobium fredii symbiotic plasmids (25, 32), as well as the complete physical map of the 240-kb pSym of an R. leguminosarum bv. viciae strain (38). A genetic map of R. meliloti megaplasmid pRmeSU47b has also been reported recently (8). In such studies, emphasis has been put on localization of specific genes and regulatory sequences. The studies reported here were focussed on the underlying structural complexity of pSym with respect to the presence of reiterated DNA Tn5-Mob element and its insertion site are also shown.

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“…biovar 1 (14,16,23,31). Nevertheless, the symbiotic plasmid of CIAT 899 can be expressed in an A. tumefaciens C58 genetic background (15), and this fact suggests a degree of phenotypic relatedness between these two strains. The metabolic properties of the R. galegae strains were closely related to those of Agrobactenum strains (cluster 4).…”

Section: Discussionmentioning

confidence: 99%

Numerical Taxonomy of Rhizobium Strains from Legumes of the Temperate Zone

Novikova¹,

Павлова²,

Vorobjev³

et al. 1994

International Journal of Systematic Bacteriology

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Phenotypic properties (growth characteristics, utilization of carbon and nitrogen sources, and intrinsic antibiotic resistance) of 53 Rhizobium strains isolated from root nodules of the temperate-zone legumes Astragalus spp. (29 strains), Oxytropis campanuhta (7 strains), Hedysarum alpinum (7 strains), Ononis awensis (3 strains), Glycyrrhiza spp. (4 strains), and Coronilh varia (3 strains) were compared with those of other Rhizobium, Bradyrhizobium, and Agrobacterium strains. The final matrix, containing 83 strains and 56 nonsymbiotic features, was used for computer cluster analysis. The dendrogram showed that the new strains of temperate-zone rhizobia formed a cluster separate from both Rhizobium and Bradyrhizobium spp. Two large groups of temperate-zone rhizobia were revealed. Group 1 included rhizobial strains originating from different geographical regions with a temperate climate, while group 2 included strains from the same geographical origin, South Siberia. The 'strains of recognized Rhizobium species were clustered, in general, with each other as expected from phylogenetic relatedness.Root nodule bacteria of the genera Rhizobium and Bradyrhizobium are a common microflora of temperate soils. These bacteria may interact with the roots of leguminous plants, inducing the formation of nodules in which the fixation of atmospheric nitrogen occurs. These bacteria are commonly used in agriculture for improvement of plant growth. The specificity of the interaction between rhizobia and legumes depends on many factors coded for by the host cultivar and bacterial genomes;. The main properties of a bacterial isolate can be described by its taxonomical position in relation to other strains. There are several Rhizobium species recognized at this time (10, 1.3, 24), and knowledge of rhizobial evolution and phylogeny obtained in recent studies allows the proposal of new rhizobial taxa (3,16,25). However, the current systematic description of the genus Rhizobium does not include many of the root nodule isolates from legumes of tropical (22, 37), arctic (21), and temperate (5, 12, 17) regions.The host plant specificities and phage sensitivities of Rhizobium strains from temperate-zone legume root nodules formed on Astragalus, Hedysamm, Glycywhiza, and Ononis plants were recently described (17). It was shown that these strains constitute a cross-inoculation group related to Rhizobium loti. The aim of the present work was to determine the cultural properties of these strains and to compare these properties with those of other Rhizobium species. MATERIALS AND METHODSBacterial strains. Bacterial strains used in this work are listed in Table 1. Bacteria were maintained on yeast extractmannitol (YEM) (29) agar slants at 4°C.Growth characteristics. The time necessary for full colony development on YEM agar (estimated here as a colony diameter of 2 mm) was determined. Bacterial growth on meat-peptone agar and reactions with litmus milk were determined as described earlier (11). The ability of strains to grow in the presence of 0,1...

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Nitrogen-fixing nodules induced by Agrobacterium tumefaciens harboring Rhizobium phaseoli plasmids

Cited by 122 publications

References 31 publications

Development of promiscous rhizobia for diverse rabi legumes (Chickpea, Pea and Lentil)

Development of promiscous rhizobia for diverse rabi legumes (Chickpea, Pea and Lentil)

Structural complexity of the symbiotic plasmid of Rhizobium leguminosarum bv. phaseoli

Numerical Taxonomy of Rhizobium Strains from Legumes of the Temperate Zone

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