Release of transgenic bacterial inoculants - rhizobia as a case study

Hirsch, P. R.

doi:10.1007/s11104-005-4992-3

Cited by 28 publications

(17 citation statements)

References 27 publications

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“…Such behavior confirms in soil the genetic stability we observed with the same strains within inoculant packages in the prior long-term (500 days) microcosm trial (Corich et al, 1996). Examples of variable persistence of GM rhizobia are found in the literature (Hirsch, 2004) and in some instances such behavior is site-dependent. An hitherto persistent strain of R. leguminosarum bv.…”

Section: Discussionsupporting

confidence: 83%

Long term evaluation of field-released genetically modified rhizobia

Corich

Vendramin

Vian

et al. 2007

Environ. Biosafety Res.

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This is the report of the first open field release of genetically modified microorganisms (GMMs) in Italy. It covers ten years of monitoring, and follows in-field GMM dynamics from strain release to disappearance below detection limits, as well as assessment of impact on resident microorganisms. The bacteria released belong to the nitrogen fixing legume endosymbiont Rhizobium leguminosarum bv. viciae, and were engineered with non-agronomically-proficient traits, in order to assess their behavior and fate without GMM-specific positive feedback from the plant. A DNA cassette containing mercury resistance and ß-galactosidase genes was introduced in either plasmid-borne or chromosomally integrated versions, in order to test the resulting strain stability. A synthetic promoter was used to drive the lacZ gene, conferring high catabolic activity to the GMM. Two different wild-type Rhizobium backgrounds were tested, comparing a non-indigenous vs. an indigenous, highly competitive strain. The latter had much greater persistence, since it was able to survive and establish at technically detectable levels for over four years after release. Selection factors, such as reiterated presence of the plant host, or lactose substrate supply, enhanced long-term survival to different extents. The lactose treatment showed that even a single trophic supplementation can surpass the benefits of symbiotic interaction for a period of several years. Concerning impact, the GMMs did not alter substantially the other soil community general microbiota. However, there were some significant differences in microbiota as a consequence of the Rhizobium inoculation. This effect was observed with either the WT or GMM, and was more evident in the release of the indigenous Rhizobium. Moreover, as the indigenous GMM had its parental, dominant wild-type in the same soil, it was possible to evaluate to what extent the GMM version could result in parent displacement ("self-impact"), and how much the two rhizobia would additively contribute to nodulation.

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Section: Discussionsupporting

confidence: 83%

Long term evaluation of field-released genetically modified rhizobia

Corich

Vendramin

Vian

et al. 2007

Environ. Biosafety Res.

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“…There is strong experimental and historical evidence for conjugative transfer of these large plasmids, and this is likely to have been vital for the evolution of rhizobia, particularly their ability to establish nitrogen-fixing symbioses with leguminous plants. Trials using genetically modified rhizobia strains have been carried out for some time (Hirsch 2004). However, agricultural releases of either natural or genetically modified rhizobia often encounter problems including poor survival and persistence of rhizobia after release, unsuccessful competition with natural microflora, and nonimprovement in crop yields (Ronson et al 1990;Bosworth et al 1994;Scupham et al 1996;Robleto et al 1997Robleto et al , 1998Amarger 2002;Hirsch 2004).…”

Section: Resultsmentioning

confidence: 99%

“…Trials using genetically modified rhizobia strains have been carried out for some time (Hirsch 2004). However, agricultural releases of either natural or genetically modified rhizobia often encounter problems including poor survival and persistence of rhizobia after release, unsuccessful competition with natural microflora, and nonimprovement in crop yields (Ronson et al 1990;Bosworth et al 1994;Scupham et al 1996;Robleto et al 1997Robleto et al , 1998Amarger 2002;Hirsch 2004). We do not understand the role that plasmid transfer between introduced strains and indigenous strains may play in the lack of success of inoculants or the generation of new strains in the soil that can outcompete the introduced strains.…”

Section: Resultsmentioning

confidence: 99%

Plasmid transfer systems in the rhizobia

Ding

Hynes

2009

Can. J. Microbiol.

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Rhizobia are agriculturally important bacteria that can form nitrogen-fixing nodules on the roots of leguminous plants. Agricultural application of rhizobial inoculants can play an important role in increasing leguminous crop yields. In temperate rhizobia, genes involved in nodulation and nitrogen fixation are usually located on one or more large plasmids (pSyms) or on symbiotic islands. In addition, other large plasmids of rhizobia carry genes that are beneficial for survival and competition of rhizobia in the rhizosphere. Conjugative transfer of these large plasmids thus plays an important role in the evolution of rhizobia. Therefore, understanding the mechanism of conjugative transfer of large rhizobial plasmids provides foundations for maintaining, monitoring, and predicting the behaviour of these plasmids during field release events. In this minireview, we summarize two types of known rhizobial conjugative plasmids, including quorum sensing regulated plasmids and RctA-repressed plasmids. We provide evidence for the existence of a third type of conjugative plasmid, including pRleVF39c in Rhizobium leguminosarum bv. viciae strain VF39SM, and we provide a comparison of the different types of conjugation genes found in members of the rhizobia that have had their genomes sequenced so far.

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“…En línea con lo expuesto, Hirsch (2004) señaló que el uso de inoculantes microbiales, en agricultura y horticultura, para mejorar la nutrición y el crecimiento e inhibir pestes y patógenos vegetales es una práctica ampliamente utilizada. Adicionalmente, se han reportado microorganismos endó-fitos que viven en el interior de las plantas sin causar efectos negativos, que brindan una fuente potencial de productos naturales, con diversas finalidades: medicina, agricultura e industria; los que han sido encontrados y aislados, en forma incremental, a partir de los vegetales (Guo et al, 2008).…”

Section: Importancia De La Biodiversidad Para La Agriculturaunclassified

Importancia de los recursos genéticos de la agrobiodiversidad en el desarrollo de sistemas de producción sostenibles

Lobo

2009

CTA

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Desde la óptica de la diversidad genética, Colombia es un país megadiverso con variabilidad ecosistémica importante, la cual puede ser aprovechada para el desarrollo de sistemas de producción sostenibles, eficientes y competitivos. Esto implica, aparte de la conservación de los recursos genéticos estratégicos vegetales, animales y de microorganismos, conocer el potencial de esta agrobiodiversidad para su utilización amplia, con apoyo de procesos convencionales y de la biotecnología moderna, que permitan proveer alimentos y el desarrollo del concepto integral del manejo de agroecosistemas. Por ello, en la revisión actual se incluye una descripción de la importancia de la diversidad biológica agrícola, en el nuevo contexto mundial y la necesidad de realizar procesos de conocimiento de la variabilidad y los atributos presentes en ésta, para trasladar el recurso genético de valor de existencia a los de opción y utilización. Agrobiodiversity relevance, at genetic resources level, for the development of sustainable production systemsColombia is a megadiverse country, from the viewpoint of genetic diversity, with ample ecosystem variability, which can be employed for the development of sustainable production systems, efficient and competitive. This means, besides conservation of strategic genetic resources of plants, animals and microorganisms, to know the potential of this agrobiodiversity for its ample utilization, with the support of conventional procedures and those from the modern biotechnology, which allow the efficient production of food and feed, as well as the implementation of the novel concept of integrated management of agroecosystems. Thus, in the current review, are included, in the new world context, the importance of the agricultural biological diversity, as well as the actions to be developed in order to translate the agrobiodiversity from existence value to option and use values.

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Release of transgenic bacterial inoculants - rhizobia as a case study

Cited by 28 publications

References 27 publications

Long term evaluation of field-released genetically modified rhizobia

Long term evaluation of field-released genetically modified rhizobia

Plasmid transfer systems in the rhizobia

Importancia de los recursos genéticos de la agrobiodiversidad en el desarrollo de sistemas de producción sostenibles

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