Influence of Age and Stage of Development on the Neutral Carbohydrate Components in Root Exudates From Alfalfa Plants Grown in a Gnotobiotic Environment

Hamlen, R. A.; Lukezic, F. L.; Bloom, J. R.

doi:10.4141/cjps72-097

Cited by 68 publications

(35 citation statements)

References 5 publications

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“…Similar results have been obtained using transgenic Lotus plants producing opines, albeit only after 6, 10, and 14 weeks as the experiment was discontinued after 14 weeks (data not shown). This result is of interest because it has been shown previously that the microbial community selected by a plant varies according to the developmental stage of the plant (6,16,27), a feature that also relates to legume species (9). The apparent stability of the opine-induced bias suggests that the compositions of the root exudates of the Lotus and S. nigrum plants used in this study remained steady while the experiment lasted.…”

Section: Vol 68 2002 Engineering Plant-microbe Interactions 2563mentioning

confidence: 72%

Engineered Rhizosphere: the Trophic Bias Generated by Opine-Producing Plants Is Independent of the Opine Type, the Soil Origin, and the Plant Species

Mansouri

Petit

Oger

et al. 2002

Appl Environ Microbiol

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In a previous study, we demonstrated that transgenic Lotus plants producing opines (which are small amino acid and sugar conjugates) specifically favor growth of opine-degrading rhizobacteria. The opine-induced bias was repeated and demonstrated with another soil type and another plant species (Solanum nigrum). This phenomenon is therefore independent of both soil type and plant species.The use of microorganisms as biopesticides or plant growth enhancers is an attractive alternative to the use of chemical pesticides and fertilizers (3,10,12,35,37). However, introduction of plant-growth-promoting bacteria in open fields often fails. This is attributed to limited survival of the inoculant strain in the rhizosphere, where it faces competition from resident microorganisms, a diverse community well adapted to the biological and physicochemical properties of the plant-soil interface (37). It is therefore crucial to develop methods to extend the fitness and persistence of the inoculant microorganisms, possibly by introducing a bias in the competition that benefits the isolate inoculated (20). This bias may be generated by addition to the soil, or release by the plant, of one or more substrates utilizable only by the introduced strain. This approach has been successfully used to sustain growth of various microbes in soil (1, 2, 5). Similarly, plants engineered to produce bacterial growth substrates have been shown to specifically select populations of microbes utilizing these substrates in the rhizospheres of Lotus (8, 21) and tobacco plants (31). Most often, these growth substrates have been opines (4), a family of compounds derived from amino acids and/or sugars and specifically detected in the crown gall tumors and hairy root formations induced by members of the genus Agrobacterium (4).Bacterial populations are highly dependent upon soil type (13,14,24,23,32) and plant exudates (7,15,17,38). Therefore, there is a risk that a selective microbial substrate strategy might be successful for a single soil type or a single plant species or cultivar. The work described here was aimed at determining whether the impact of opine production on soil bacteria is independent of the type of opines produced by the plant, the origin of the soil, and the plant species producing the opines. Such investigations are crucial to evaluate whether opine-producing plants and biased rhizosphere strategies could be used to engineer plant-microbe interactions under various conditions.To address the questions above, plants of the legume Lotus corniculatus cv. Rodéo and Solanum nigrum plants were engineered via Agrobacterium rhizogenes transformation to produce opines, as described by Petit et al. (26). The transformed plants produced the opines mannopine, mannopine and nopaline, or mannopine and octopine; the latter opine has not been tested previously (Fig. 1) (for a review, see reference 4). Transformed control plants harboring the pRi oncogenes but producing no opines (ONC plants) were also generated by using the same procedure (26). Plants we...

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Section: Vol 68 2002 Engineering Plant-microbe Interactions 2563mentioning

confidence: 72%

Engineered Rhizosphere: the Trophic Bias Generated by Opine-Producing Plants Is Independent of the Opine Type, the Soil Origin, and the Plant Species

Mansouri

Petit

Oger

et al. 2002

Appl Environ Microbiol

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“…It is conceivable that Agrostis and Andropogon rhizosphere bacterial compositions were responding to rhizodeposition patterns corresponding to a plant trait common to both grass species. For instance, as plants age, root exudation quantities can decrease and change in quality [2,15,28]. Further, rhizosphere microbial communities can initially be dominated by r-strategists, such as Proteobacteria.…”

Section: Discussionmentioning

confidence: 99%

Temporal Dynamics in Rhizosphere Bacterial Communities of Three Perennial Grassland Species

2016

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Abstract:Rhizodeposition is considered a primary reason for the plant identity effect. However, the detection of distinct rhizosphere bacterial communities (RBC) with different plant species has been variable. The aim of this study was to examine the potential explanations for this variability using three perennial grassland species. In a Kansas field experiment, over two growing seasons, we sampled RBC during the active growth and flowering stages of Agrostis gigantea, Andropogon gerardii and Helianthus maximiliani to: (1) determine the extent of the plant identity effect among these species and if the effect was maintained over time; (2) assess if RBC showed seasonal patterns, corresponding to plant phenology; and (3) examine if soil properties were important for structuring these communities. We found that Helianthus RBC were distinct from those of Agrostis and Andropogon only when Helianthus was flowering. Further, Helianthus RBC exhibited seasonal shifts corresponding to plant phenology. In contrast, Agrostis and Andropogon RBC were similar over time and exhibited gradual non-seasonal changes in compositions. Similar results were observed when accounting for soil properties. Overall, the observance of a plant identity effect depended on the plant species and when RBC were sampled. The seasonality of RBC also depended on the plant species examined.

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“…However, in our experiment these factors were similar for all treatments. The quality and quantity of root exudates produced by alfalfa depend on its age and stage of development (14). As root exudates are an important source of nutrition for many rhizosphere microorganisms, changes in their composition may affect the patterns and activities of rhizobacterial populations.…”

Section: Discussionmentioning

confidence: 99%

Effect of a Sinorhizobium meliloti Strain with a Modified putA Gene on the Rhizosphere Microbial Community of Alfalfa

Dillewijn

Villadas

Toro

2002

Appl Environ Microbiol

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The success of a rhizobial inoculant in the soil depends to a large extent on its capacity to compete against indigenous strains. M403, a Sinorhizobium meliloti strain with enhanced competitiveness for nodule occupancy, was recently constructed by introducing a plasmid containing an extra copy of a modified putA (proline dehydrogenase) gene. This strain and M401, a control strain carrying the same plasmid without the modified gene, were used as soil inoculants for alfalfa in a contained field release experiment at León, Spain. In this study, we determined the effects of these two strains on the indigenous microbial community. 16S rRNA genes were obtained from the rhizosphere of alfalfa inoculated with strain M403 or strain M401 or from noninoculated plants by amplification of DNA from soil with bacterial group-specific primers. These genes were analyzed and compared by restriction fragment length polymorphism and temperature gradient gel electrophoresis. The results allowed us to differentiate between alterations in the microbial community apparently caused by inoculation and by the rhizosphere effect and seasonal fluctuations induced by the alfalfa plants and by the environment. Only moderate inoculation-dependent effects could be detected, while the alfalfa plants appeared to have a much stronger influence on the microbial community.

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Influence of Age and Stage of Development on the Neutral Carbohydrate Components in Root Exudates From Alfalfa Plants Grown in a Gnotobiotic Environment

Abstract: Investigations were carried out by gas-liquid components increased with time. Based

Cited by 68 publications

References 5 publications

Engineered Rhizosphere: the Trophic Bias Generated by Opine-Producing Plants Is Independent of the Opine Type, the Soil Origin, and the Plant Species

Engineered Rhizosphere: the Trophic Bias Generated by Opine-Producing Plants Is Independent of the Opine Type, the Soil Origin, and the Plant Species

Temporal Dynamics in Rhizosphere Bacterial Communities of Three Perennial Grassland Species

Effect of a Sinorhizobium meliloti Strain with a Modified putA Gene on the Rhizosphere Microbial Community of Alfalfa

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