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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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Nodule appearance (size and colour) at later stages of the symbiotic interaction. MG-20 nodules induced by NGR234 and M. loti 8 wpi (A & C) or 20 wpi (B & D); MG-20 possessed exclusively red nodules (2–4 mm diameter) when inoculated with MAFF303099. In contrast, NGR234 provoked the formation of both red and small green nodules at 8 weeks (C), and at 20 weeks larger red nodules could be seen (D). The diameters of nodules were assigned to three classes (Cl) at 8 wpi (Cl1 <1 mm, Cl2 >1 mm, and Cl3 >1.5 mm). Bars represent average distributions of all the nodules from four pots with standard deviations indicated (E and F).
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fig4: Nodule appearance (size and colour) at later stages of the symbiotic interaction. MG-20 nodules induced by NGR234 and M. loti 8 wpi (A & C) or 20 wpi (B & D); MG-20 possessed exclusively red nodules (2–4 mm diameter) when inoculated with MAFF303099. In contrast, NGR234 provoked the formation of both red and small green nodules at 8 weeks (C), and at 20 weeks larger red nodules could be seen (D). The diameters of nodules were assigned to three classes (Cl) at 8 wpi (Cl1 <1 mm, Cl2 >1 mm, and Cl3 >1.5 mm). Bars represent average distributions of all the nodules from four pots with standard deviations indicated (E and F).

Mentions: Nodules induced by MAFF303099 on MG-20 rapidly developed into spherical red organs of >1.5 mm diameter (Fig. 4A, F) that were long lasting, appeared unchanged even at 20 wpi (Fig. 4A, B). At 8 wpi, when MG-20 plants inoculated with NGR234 were clearly larger than mock-inoculated controls, the majority of nodules were still <1 mm in diameter (Fig. 4C, 4E). At 20 wpi, NGR234-inoculated plants were even larger (data not shown) and possessed red nodules, a few of which had diameters of >3 mm (Fig. 4D).


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)

Nodule appearance (size and colour) at later stages of the symbiotic interaction. MG-20 nodules induced by NGR234 and M. loti 8 wpi (A & C) or 20 wpi (B & D); MG-20 possessed exclusively red nodules (2–4 mm diameter) when inoculated with MAFF303099. In contrast, NGR234 provoked the formation of both red and small green nodules at 8 weeks (C), and at 20 weeks larger red nodules could be seen (D). The diameters of nodules were assigned to three classes (Cl) at 8 wpi (Cl1 <1 mm, Cl2 >1 mm, and Cl3 >1.5 mm). Bars represent average distributions of all the nodules from four pots with standard deviations indicated (E and F).
© Copyright Policy - open-access
Related In: Results  -  Collection

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

fig4: Nodule appearance (size and colour) at later stages of the symbiotic interaction. MG-20 nodules induced by NGR234 and M. loti 8 wpi (A & C) or 20 wpi (B & D); MG-20 possessed exclusively red nodules (2–4 mm diameter) when inoculated with MAFF303099. In contrast, NGR234 provoked the formation of both red and small green nodules at 8 weeks (C), and at 20 weeks larger red nodules could be seen (D). The diameters of nodules were assigned to three classes (Cl) at 8 wpi (Cl1 <1 mm, Cl2 >1 mm, and Cl3 >1.5 mm). Bars represent average distributions of all the nodules from four pots with standard deviations indicated (E and F).
Mentions: Nodules induced by MAFF303099 on MG-20 rapidly developed into spherical red organs of >1.5 mm diameter (Fig. 4A, F) that were long lasting, appeared unchanged even at 20 wpi (Fig. 4A, B). At 8 wpi, when MG-20 plants inoculated with NGR234 were clearly larger than mock-inoculated controls, the majority of nodules were still <1 mm in diameter (Fig. 4C, 4E). At 20 wpi, NGR234-inoculated plants were even larger (data not shown) and possessed red nodules, a few of which had diameters of >3 mm (Fig. 4D).

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