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Biomedical subjects

Paula M Olhoft

Publications and source records attributed to Paula M Olhoft.

4 recordsLinked to original sources
PubMed2006

Soybean (Glycine max) transformation using mature cotyledonary node explants.

Agrobacterium tumefaciens-mediated transformation of soybeans has been steadily improved since its development in 1988. Soybean transformation is now possible in a range of genotypes from different maturity groups using different explants as sources of regenerable cells, various selectable marker genes and selective agents, and different A. tumefaciens strains. The cotyledonary-node method has been extensively investigated and across a number of laboratories yields on average greater than 1% transformation efficiency (one Southern-positive, independent event per 100 cotyledonary-node explants). Continued improvements in the cotyledonary-node method concomitant with further increases in transformation efficiency will enhance broader adoption of this already productive transformation method for use in crop improvement and functional genomics research efforts.

Agrobacterium tumefaciens↗
PubMed2004

T-DNA locus structure in a large population of soybean plants transformed using the Agrobacterium-mediated cotyledonary-node method.

Designing transformation experiments for either functional genomics or crop improvement requires knowledge of the transgene locus structure, number, transmission and expression resulting from a specific transformation method. We recently reported an improvement to the soybean [Glycine max (L.) Merrill] cotyledonary-node transformation method that resulted in the efficient production of transgenic plants. To characterize the transgene loci resulting from this method, we analysed 270 independent T0 plants and 95 randomly selected T1 progenies for T-DNA locus complexity using Southern analysis. The lines were transformed with Agrobacterium tumefaciens strains LBA4404 or EHA105 carrying the binary plasmids pGPTV, pTOK233, pCAMBIA1303 or pCAMBIA1309, and regenerated in medium supplemented with or without silver nitrate (AgNO3). Analysis in the T0 generation showed that the number of hpt-hybridizing fragments per plant ranged from 1-15, with 31.5% of the lines having a single hpt-hybridizing fragment. Each primary soybean transformant had, on average, 2.0 unlinked transgene loci and that half of the segregating loci in the T1 progenies were single, simple T-DNA insertions. Of the loci containing multiple T-DNA fragments, a low frequency had tandem and inverted repeat T-DNA structures. Integration of binary plasmid backbone sequences occurred in 37% of primary transformants. A. tumefaciens strain, binary plasmid and thiol treatment had no significant effect on transgene locus structure, numbers or expression. Interestingly, exposure of soybean explants to AgNO3 throughout shoot induction and elongation increased T-DNA locus complexity in the primary transformants and decreased silencing of gusA expression in the T1 generation.

Journal Article↗
PubMed2002

Efficient soybean transformation using hygromycin B selection in the cotyledonary-node method.

The efficiency of soybean [Glycine max (L.) Merrill] transformation was significantly increased from an average of 0.7% to 16.4% by combining strategies to enhance Agrobacterium tumefaciens-mediated T-DNA delivery into cotyledonary-node cells with the development of a rapid, efficient selection protocol based on hygromycin B. Wounded cotyledonary-node explants were inoculated with A. tumefaciens carrying either a standard-binary or super-binary plasmid and co-cultivated in the presence of mixtures of the thiol compounds, L-cysteine, dithiothreitol, and sodium thiosulfate. Transformed shoots began elongating only 8 weeks after co-cultivation. Southern analysis confirmed integration of the T-DNA into genomic DNA and revealed no correlation between the complexity of the integration pattern and thiol treatment applied at co-cultivation. All T(0) plants were fertile and the majority of the lines transmitted the beta-glucuronidase (GUS) phenotype in 3:1 or 15:1 ratios to their progenies.

Agrobacterium tumefaciens↗