Root-based N2-fixing Symbioses: Legumes, Actinorhizal Plants, Parasponia sp. and Cycads

Vessey, J. Kevin; Pawlowski, Katharina; Bergman, Birgitta

doi:10.1007/s11104-005-5881-5

Cited by 104 publications

(81 citation statements)

References 240 publications

(220 reference statements)

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“…Root exudates from legumes are a chemoattractant for motile Rhizobium bacterium, but Frankia is a nonmotile bacterium (12,31). Frankia CcI3 grows in the rhizosphere of C. cunninghamiana, which suggests that a chemotrophic response is possible, but it has not yet been studied (20,36,37).…”

Section: Production Of Aqueous Root Exudates and General Propertiesmentioning

confidence: 99%

Casuarina Root Exudates Alter the Physiology, Surface Properties, and Plant Infectivity of Frankia sp. Strain CcI3

Beauchemin

Furnholm

Lavenus

et al. 2012

Appl Environ Microbiol

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The actinomycete genus Frankia forms nitrogen-fixing symbioses with 8 different families of actinorhizal plants, representing more than 200 different species. Very little is known about the initial molecular interactions between Frankia and host plants in the rhizosphere. Root exudates are important in Rhizobium-legume symbiosis, especially for initiating Nod factor synthesis. We measured differences in Frankia physiology after exposure to host aqueous root exudates to assess their effects on actinorhizal symbioses. Casuarina cunninghamiana root exudates were collected from plants under nitrogen-sufficient and -deficient conditions and tested on Frankia sp. strain CcI3. Root exudates increased the growth yield of Frankia in the presence of a carbon source, but Frankia was unable to use the root exudates as a sole carbon or energy source. Exposure to root exudates caused hyphal "curling" in Frankia cells, suggesting a chemotrophic response or surface property change. Exposure to root exudates altered Congo red dye binding, which indicated changes in the bacterial surface properties at the fatty acid level. Fourier transform infrared spectroscopy (FTIR) confirmed fatty acid changes and revealed further carbohydrate changes. Frankia cells preexposed to C. cunninghamiana root exudates for 6 days formed nodules on the host plant significantly earlier than control cells. These data support the hypothesis of early chemical signaling between actinorhizal host plants and Frankia in the rhizosphere.A ctinorhizal symbioses are mutualistic interactions that occur between actinorhizal plants and the actinomycete genus Frankia (27,38). Frankia exists either in a free-living state in the soil or in symbiosis with actinorhizal plants (2, 4, 31). Actinorhizal plants consist of 8 different plant families, including over 200 different species of woody dicotyledonous trees and shrubs (31,38,42). The globally distributed actinorhizal plants are found on every continent except Antarctica and are able to grow in a diverse set of natural habitats, including arid lands, plains, tundra, and temperate forests. Actinorhizal plants are pioneer plant species that are able to grow in extremely nutrient-poor soil conditions and, with the aid of Frankia, are able to reclaim surrounding soil in disrupted environments. Actinorhizal plants are important in agroforestry, in soil reclamation, and as a fuel source.While actinorhizal symbiosis has been well studied at a morphological level since the 1970s, very little is known about the molecular interactions that occur between the plant hosts and Frankia during the establishment of the association. The establishment of the symbiosis encompasses the infection and nodulation processes (23,27,38). In general, the bacterium needs to recognize a host plant and the host needs to identify the bacterium as a friend, not a foe. The bacteria enter the plant and establish the association after several steps. The infection ultimately leads to the formation of the mature nodule.There is a paucity of information o...

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Section: Production Of Aqueous Root Exudates and General Propertiesmentioning

confidence: 99%

Casuarina Root Exudates Alter the Physiology, Surface Properties, and Plant Infectivity of Frankia sp. Strain CcI3

Beauchemin

Furnholm

Lavenus

et al. 2012

Appl Environ Microbiol

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“…This could be related to the fact that clover is a legume with root nodules containing essential nitrogen-fixing microorganisms (e.g. Vessey et al, 2005), and it may be that elevated soil CO2 affects the activity of these organisms. It must be pointed out, however, that other factors such as photosynthetic pathway, plant age, and nitrogen concentration may produce similar results, and thus more research is needed to understand the actual mechanism of clover disappearance.…”

Section: Zone 2bmentioning

confidence: 99%

The impact of a naturally occurring CO2 gas vent on the shallow ecosystem and soil chemistry of a Mediterranean pasture (Latera, Italy)

Beaubien

Ciotoli

Coombs

et al. 2008

International Journal of Greenhouse Gas Control

134

109

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Recent research into C02 geological storage has shown that it has potential to be a safe and effective way to rapidly decrease short-term anthropogenic C02 emissions. Despite this progress, stakeholders must be convinced that the scientific community has studied all possible scenarios, including a potential leak into the biosphere. To better understand the potential impact of such an event, a detailed geochemical and biological study was conducted during two different seasons on a naturally occurring gas vent located within a Mediterranean pasture ecosystem (Latera geothermal field, central Italy). Results from botanical, soil gas, and gas flux surveys, and from chemical and biological analyses of shallow soil samples (0-20 cm depth), show that a significant impact is only observed in the 6 In wide centre of the vent, where C02 flux rates exceed 2000-3000 g M-2 d-1. In this "vent core" there is no vegetation, pH is low (minimum 3.5), and small changes are observed in mineralogy and bulk chemistry. in addition, microbial activities and populations are regulated in this interval by near-anoxic conditions, and by elevated soil gas C02 (>95%) and trace reduced gases (CH4, H2S, and 142). An approximately 20 In wide halo surrounding the core forms a transition zone, over which there is a gradual decrease in C02 concentrations, a rapid decrease in C02 fluxes, and the absence of reactive gas species. In this transition zone grasses dominate near the vent core, but these are progressively replaced by clover and a greater plant diversity moving away from the vent centre. Physical parameters (e.g. pH, bulk chemistry, mineralogy) and microbial systems also gradually return to background values across this transition zone. Results indicate that, even at this anomalous high-flux site, the effects ofthe gas vent are spatially limited and that the ecosystem appears to have adapted to the different conditions through species substitution or adaptation. (c) 2008 Elsevier Ltd. All rights reserved

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“…Awareness of the benefits of cross inoculation as a means of comparing symbiotic effectiveness of wild rhizobial strains with cultivated strains has increased in the past (Amarger, 2001;Vessey, et al, 2004;Zhang, et al, 1991). The cross-inoculation of legumes of agricultural importance with rhizobial isolates from wild legumes resulted in an increase in dry matter and total nitrogen contents of cross infected plants (Iqbal and Mahmood, 1992;Lalani Wijesundra, et al, 2000;Zahran, et al, 1999).…”

Section: Introductionmentioning

confidence: 99%

Cross inoculation studies: Response of Vigna mungo to inoculation with rhizobia from tree legumes growing under arid Environment

Mahmood

Athar

2007

Int. J. Environ. Sci. Technol.

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Cross-inoculation experiments were conducted in the greenhouse to test the rhizobia isolated from nodules of seven tree legumes for their effectiveness in Vigna mungo plants. The tree legumes included Albizia lebbeck, Dalbergia sissoo, Leucaena leucocephala, Pithecellobium dulce, Prosopis cineraria, Prosopis glandulosa and Prosopis juliflora, all growing under arid environment. Rhizobia from these legumes formed nodules on the roots of Vigna mungo except isolates from Albizia lebbeck. Dry weight and nitrogen contents of Vigna mungo plants increased significantly (P<0.05) in response to cross inoculation as compared to uninoculated control. Rhizobia from Leucaena leucocephala and Prosopis glandulosa showed significant increase in dry weight (P<0.05) and nitrogen contents (P<0.05) than other inoculated treatments. The natural rhizobia of wild tree legumes growing under arid environment show higher tolerance to prevailing adverse conditions like salt stress, elevated temperatures and drought. These rhizobia may be used to inoculate wild as well as crop legumes cultivated in reclaimed desert lands. These rhizobia may have specific traits that can be transferred to other rhizobia through genetic engineering tools. The cross infection of agriculturally important legumes with isolates from wild legumes may prove a useful means of increasing nitrogen contents within these plants.

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Root-based N2-fixing Symbioses: Legumes, Actinorhizal Plants, Parasponia sp. and Cycads

Cited by 104 publications

References 240 publications

Casuarina Root Exudates Alter the Physiology, Surface Properties, and Plant Infectivity of Frankia sp. Strain CcI3

Casuarina Root Exudates Alter the Physiology, Surface Properties, and Plant Infectivity of Frankia sp. Strain CcI3

The impact of a naturally occurring CO2 gas vent on the shallow ecosystem and soil chemistry of a Mediterranean pasture (Latera, Italy)

Cross inoculation studies: Response of Vigna mungo to inoculation with rhizobia from tree legumes growing under arid Environment

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