General Genetic Knowledge

Hynes, Michael F.; Finan, Turlough M.

doi:10.1007/978-94-011-5060-6_2

Cited by 10 publications

(13 citation statements)

References 215 publications

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“…The conventional plasmid curing methods, which involve culturing at high temperature or in the presence of EtBr and/ or detergents, have been applied to Agrobacterium (Van Larebeke et al, 1974;Lin and Kado et al, 1977). Unfortunately, these are not applicable for all Agrobacterium strains (Hynes and Finan, 1998), especially for newly isolated wild strains. In fact, we could not isolate a pTi-less strain of MAFF301001 by conventional treatment with high temperature and EtBr.…”

Section: Discussionmentioning

confidence: 99%

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A novel plasmid curing method using incompatibility of plant pathogenic Ti plasmids in Agrobacterium tumefaciens.

2002

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Ti (Tumor inducing) plasmids in Agrobacterium tumefaciens can transfer their T-DNA region into dicotyledonous plants, in which the expression of T-DNA genes causes plant tumors and the production of bacterial nutrients, e.g., opines such as nopaline. Naturally occurring Ti plasmids (pTi) are difficult to cure by conventional curing methods because of their high stability. Here, we developed a novel curing method based on plasmid incompatibility. For this, a curing plasmid, pMGTrep1, was newly constructed and subsequently introduced into A. tumefaciens strains harboring pTi by conjugation with Escherichia coli harboring pMGTrep1. The conjugation yielded 32-99% nopaline non-utilizing agrobacterial transconjugants in which pMGTrep1 replaced pTi due to incompatibility. Then, pMGTrep1-less derivatives of the transconjugants are easily selected in the presence of sucrose because pMGTrep1 contains a sucrose-sensitive sacB gene. This efficient method is directly applicable for curing plasmids with the same incompatibility group and shoud also applicable to other types of plasmids in Agrobacterium groups, including A. rhizogenes, by replacing the rep gene region of the curing plasmid with that of the corresponding incompatibility.

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Section: Discussionmentioning

confidence: 99%

“…Unfortunately, naturally occurring pTi and pRi are very stably maintained from generation to generation in their hosts. Therefore, conventional plasmid curing methods are not always applicable (Hynes and Finan, 1998). Like other conjugative plasmids, pTi and pRi display incompatibility, i. e., closely related plasmids exclude each other.…”

Section: Introductionmentioning

confidence: 99%

A novel plasmid curing method using incompatibility of plant pathogenic Ti plasmids in Agrobacterium tumefaciens.

2002

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Section: Introductionmentioning

confidence: 99%

“…They are also of interest because of the variety of their genome organizations and the complexity of their genomes (Hynes & Finan, 1998;Galibert et al, 2001). The occurrence of large plasmids is a common feature of these bacteria, and in the fast-growing rhizobia, including the genera Sinorhizobium and Rhizobium, plasmids can make up as much as 40 % of the total genome size (Hynes et al, 1989;Hynes & Finan, 1998;Galibert et al, 2001). Recent genome sequencing projects (Kaneko et al, 2000(Kaneko et al, , 2002Galibert et al, 2001;Wood et al, 2001;DelVecchio et al, 2002;Streit et al, 2004) have confirmed the variety and complexity of the genomes of the rhizobia and their closest relatives among the alphaproteobacteria, as well as revealing much about their biology.…”

Section: Introductionmentioning

confidence: 99%

Characterization of genes involved in erythritol catabolism in Rhizobium leguminosarum bv. viciae

et al. 2006

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A genetic locus encoding erythritol uptake and catabolism genes was identified in Rhizobium leguminosarum bv. viciae, and shown to be plasmid encoded in a wide range of R. leguminosarum strains. A Tn5-B22 mutant (19B-3) unable to grow on erythritol was isolated from a mutant library of R. leguminosarum strain VF39SM. The mutated gene eryF was cloned and partially sequenced, and determined to have a high homology to permease genes of ABC transporters. A cosmid complementing the mutation (pCos42) was identified and was shown to carry all the genes necessary to restore the ability to grow on erythritol to a VF39SM strain cured of pRleVF39f. In the genomic DNA sequence of strain 3841, the gene linked to the mutation in 19B-3 is flanked by a cluster of genes with high homology to the known erythritol catabolic genes from Brucella spp. Through mutagenesis studies, three distinct operons on pCos42 that are required for growth on erythritol were identified: an ABC-transporter operon (eryEFG), a catabolic operon (eryABCD) and an operon (deoR-tpiA2-rpiB) that encodes a gene with significant homology to triosephosphate isomerase (tpiA2). These genes all share high sequence identity to genes in the erythritol catabolism region of Brucella spp., and CLUSTALW alignments suggest that horizontal transfer of the erythritol locus may have occurred between R. leguminosarum and Brucella. Transcription of the eryABCD operon is repressed by EryD and is induced by the presence of erythritol. Mutant 19B-3 was impaired in its ability to compete against wild-type for nodulation of pea plants but was still capable of forming nitrogen-fixing nodules.

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“…El término "megaplásmido" fue acuñado para hacer referencia a los plásmidos más grandes ya sean simbióticos o no (Rosemberg et al 1982). Hynes y Finan (1997), sugieren que el término megaplásmido sólo sea utilizado para plásmidos mayores de 1000 kb y no para haeer referencia a plásmidos de menor tamaño. En muchos rizobios el ADN plasmídico puede llegar constituir un porcentaje muy significativo del ADN bacteriano como en R. Etli, por ejemplo, en que representa 45% del genoma (Martinez- Romero y Palacios, 1990;Martinez-Romero, 1994).…”

Section: Características Generales Y De Transferencia De Plásmídos Deunclassified

Identificación y caracterización molecular de plásmidos transmisibles por conjugación de aislamientos locales en Sinorhizobium meliloti

Pistorio¹

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El uso de cepas inoculantes -tanto salvajes como recombinantes- requiere controlar la capacidad simbiótica de los rizobios así como los riesgos derivados de su liberación en suelos de cultivo (estudios de la evaluación de riesgos, risk assesment). Dicho control resulta más importante si se considera el creciente desarrollo y la aparición en el mercado de nuevas cepas recombinantes. En particular, prevenir la diseminación de información genética desde rizobios introducidos al suelo en forma masiva es importante para preservar la estructura genética de las poblaciones salvajes. Eventos de transferencia génica de alta frecuencia desde las cepas introducidas puede conducir a la aparición de nuevos genotipos bacterianos cuya dinámica poblacional y propiedades simbióticas a mediano y largo plazo son difíciles de predecir. En general, es deseable que las cepas utilizadas como inoculantes por sus propiedades simbióticas, se autolimiten a corto y mediano plazo para ayudar a la conservación de la biodiversidad natural. Sobre la misma base de conservación de genotipos naturales es que deben tratar de minimizarse los eventos de transfereneia génica desde las bacterias que, útiles desde el punto de vista agropecuario, sean introducidas a campos de cultivo en forma masiva. Será por tanto importante el desarrollo de estudios de base que permitan a mediano plazo el desarrollo de herramientas genético-moleculares que permitan a mediano plazo mejorar el control de riesgo asociado a la transferencia de germoplasma desde rizobios inoculados. Objetivo General. - Caracterización funcional y molecular de sistemas genéticos involucrados en la transfereneia de plásmidos por conjugación en la bacteria fijadora de nitrógeno y simbionte de alfalfa, Sinorhizobium meliloti. Objetivos específicos, - Búsqueda y aislamiento de plásmidos crípticos movilizables en cepas locales de S. meliloti. - Evaluación de la proporción de cepas de S. meliloti que son portadoras de plásmidos movilizables y/o autotransmisibles. - Estudios de complementación funcional cruzada de funciones helper entre diferentes plásmidos crípticos (Fenómenos de re-movilización y retrotransferencia). - Identificación y caracterización molecular de genes de movilización en plásmidos indígenas

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General Genetic Knowledge

Cited by 10 publications

References 215 publications

A novel plasmid curing method using incompatibility of plant pathogenic Ti plasmids in Agrobacterium tumefaciens.

A novel plasmid curing method using incompatibility of plant pathogenic Ti plasmids in Agrobacterium tumefaciens.

Characterization of genes involved in erythritol catabolism in Rhizobium leguminosarum bv. viciae

Identificación y caracterización molecular de plásmidos transmisibles por conjugación de aislamientos locales en Sinorhizobium meliloti

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