|A. Dohm, C. Ludwig, D. Schilling, T. Debener
|Agrobacterium mediated gene transfer, somatic embryogenesis, in planta transformation, ribosome inhibiting protein, chitinase, glucanase, T4-lysozyme, signal peptide
In order to obtain partial resistance in roses to the major fungal diseases simultaneously, we followed the biotechnological approach of overexpressing genes for particular antifungal proteins.
Via Agrobacterium mediated gene transfer of somatic embryos and subsequent adventitious shoot formation different combinations of antifungal defence genes were introduced into the garden rose cultivars Heckenzauber and Pariser Charme.
The transformation frequency reached a maximum of 3 %. This number refers to the number of transgenic shoots obtained from transformed somatic embryos and was mainly determined by the regeneration capacity of the somatic embryos.
The type of carbon source in the culture medium had a significant effect on adventitious shoot formation.
Altogether, 80 true transgenic plants were analysed for expression of their transgenes and resistance to blackspot.
Compared to non transgenic control plants, the susceptibility to blackspot did not decrease in the case of cytosolic expression of the antifungal proteins, although 80 % of these plants proved to express the transgenes by Northern analysis.
The secretion of the ribosome inhibiting protein into the extracellular space, however, reduced the susceptibility against blackspot to 60 % on average.
To avoid problems of standard in vitro transformation protocols, e.g. the use of antibiotics as selectable markers, we try to establish an in planta transformation system.
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