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Delayed maturation of nodules reduces symbiotic effectiveness of the Lotus japonicus-Rhizobium sp. NGR234 interaction.

Schumpp O, Crèvecoeur M, Broughton WJ, Deakin WJ - J. Exp. Bot. (2008)

Bottom Line: It was found that NGR234 initiates nodule formation in a similar way to M. loti MAFF303099, but that the nodules which develop on eleven L. japonicus ecotypes are less efficient in fixing nitrogen.With time, these nodules develop into fully efficient organs containing bacteroids tightly enclosed in symbiosome membranes, just like those formed by M. loti MAFF303099.This work demonstrates the usefulness of using the well-characterized micro-symbiont NGR234 to study symbiotic signal exchange in the later stages of rhizobia-legume symbioses, especially given the large range of bacterial (NGR234) and plant (L. japonicus) mutants that are available.

View Article: PubMed Central - PubMed

Affiliation: Laboratoire de Biologie Moléculaire des Plantes Supérieures, Université de Genève, 30 Quai Ernest-Ansermet, Sciences III, CH-1211 Genève 4, Switzerland.

ABSTRACT
Lotus japonicus, a model legume, develops an efficient, nitrogen-fixing symbiosis with Mesorhizobium loti that promotes plant growth. Lotus japonicus also forms functional nodules with Rhizobium sp. NGR234 and R. etli. Yet, in a plant defence-like reaction, nodules induced by R. etli quickly degenerate, thus limiting plant growth. In contrast, nodules containing NGR234 are long-lasting. It was found that NGR234 initiates nodule formation in a similar way to M. loti MAFF303099, but that the nodules which develop on eleven L. japonicus ecotypes are less efficient in fixing nitrogen. Detailed examination of nodulation of L. japonicus cultivar MG-20 revealed that symbiosomes formed four weeks after inoculation by NGR234 are enlarged in comparison with MAFF303099 and contain multiple bacteroids. Nevertheless, nodules formed by NGR234 fix sufficient nitrogen to avoid rejection by the plant. With time, these nodules develop into fully efficient organs containing bacteroids tightly enclosed in symbiosome membranes, just like those formed by M. loti MAFF303099. This work demonstrates the usefulness of using the well-characterized micro-symbiont NGR234 to study symbiotic signal exchange in the later stages of rhizobia-legume symbioses, especially given the large range of bacterial (NGR234) and plant (L. japonicus) mutants that are available.

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Electron (A & B) and light (C) micrographs of 7 month-old nodules containing NGR234. Infected cells contained predominantly bacteroids closely-enveloped within peribacteroid membranes (A), or a mixture of both tight and enlarged symbiosomes (B). Viewing at lower magnification revealed some of the infected cells, dispersed throughout the nodule, presenting degraded content (C; labelled with arrowheads).
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fig6: Electron (A & B) and light (C) micrographs of 7 month-old nodules containing NGR234. Infected cells contained predominantly bacteroids closely-enveloped within peribacteroid membranes (A), or a mixture of both tight and enlarged symbiosomes (B). Viewing at lower magnification revealed some of the infected cells, dispersed throughout the nodule, presenting degraded content (C; labelled with arrowheads).

Mentions: In even older nodules, 7 months after inoculation with NGR234, sectors of tight symbiosomes were no longer visible. Some infected cells contained totally tight symbiosomes, while others showed both tight and enlarged structures (Fig. 6A, B). Occasionally infected cells presented degraded contents (Fig. 6C); their appearance was similar to that of type 1 senescent cells seen in the proximal part of the fixation zone of Medicago truncatula (Van de Velde et al., 2006).


Delayed maturation of nodules reduces symbiotic effectiveness of the Lotus japonicus-Rhizobium sp. NGR234 interaction.

Schumpp O, Crèvecoeur M, Broughton WJ, Deakin WJ - J. Exp. Bot. (2008)

Electron (A & B) and light (C) micrographs of 7 month-old nodules containing NGR234. Infected cells contained predominantly bacteroids closely-enveloped within peribacteroid membranes (A), or a mixture of both tight and enlarged symbiosomes (B). Viewing at lower magnification revealed some of the infected cells, dispersed throughout the nodule, presenting degraded content (C; labelled with arrowheads).
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC2651464&req=5

fig6: Electron (A & B) and light (C) micrographs of 7 month-old nodules containing NGR234. Infected cells contained predominantly bacteroids closely-enveloped within peribacteroid membranes (A), or a mixture of both tight and enlarged symbiosomes (B). Viewing at lower magnification revealed some of the infected cells, dispersed throughout the nodule, presenting degraded content (C; labelled with arrowheads).
Mentions: In even older nodules, 7 months after inoculation with NGR234, sectors of tight symbiosomes were no longer visible. Some infected cells contained totally tight symbiosomes, while others showed both tight and enlarged structures (Fig. 6A, B). Occasionally infected cells presented degraded contents (Fig. 6C); their appearance was similar to that of type 1 senescent cells seen in the proximal part of the fixation zone of Medicago truncatula (Van de Velde et al., 2006).

Bottom Line: It was found that NGR234 initiates nodule formation in a similar way to M. loti MAFF303099, but that the nodules which develop on eleven L. japonicus ecotypes are less efficient in fixing nitrogen.With time, these nodules develop into fully efficient organs containing bacteroids tightly enclosed in symbiosome membranes, just like those formed by M. loti MAFF303099.This work demonstrates the usefulness of using the well-characterized micro-symbiont NGR234 to study symbiotic signal exchange in the later stages of rhizobia-legume symbioses, especially given the large range of bacterial (NGR234) and plant (L. japonicus) mutants that are available.

View Article: PubMed Central - PubMed

Affiliation: Laboratoire de Biologie Moléculaire des Plantes Supérieures, Université de Genève, 30 Quai Ernest-Ansermet, Sciences III, CH-1211 Genève 4, Switzerland.

ABSTRACT
Lotus japonicus, a model legume, develops an efficient, nitrogen-fixing symbiosis with Mesorhizobium loti that promotes plant growth. Lotus japonicus also forms functional nodules with Rhizobium sp. NGR234 and R. etli. Yet, in a plant defence-like reaction, nodules induced by R. etli quickly degenerate, thus limiting plant growth. In contrast, nodules containing NGR234 are long-lasting. It was found that NGR234 initiates nodule formation in a similar way to M. loti MAFF303099, but that the nodules which develop on eleven L. japonicus ecotypes are less efficient in fixing nitrogen. Detailed examination of nodulation of L. japonicus cultivar MG-20 revealed that symbiosomes formed four weeks after inoculation by NGR234 are enlarged in comparison with MAFF303099 and contain multiple bacteroids. Nevertheless, nodules formed by NGR234 fix sufficient nitrogen to avoid rejection by the plant. With time, these nodules develop into fully efficient organs containing bacteroids tightly enclosed in symbiosome membranes, just like those formed by M. loti MAFF303099. This work demonstrates the usefulness of using the well-characterized micro-symbiont NGR234 to study symbiotic signal exchange in the later stages of rhizobia-legume symbioses, especially given the large range of bacterial (NGR234) and plant (L. japonicus) mutants that are available.

Show MeSH
Related in: MedlinePlus