ISSN:
1573-5060
Keywords:
Agrobacterium tumefaciens
;
Beta vulgaris
;
sugar beet
;
regeneration
;
shooter mutants
;
transformation
Source:
Springer Online Journal Archives 1860-2000
Topics:
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
Notes:
Summary Beta vulgaris plants were found to be susceptible to Agrobacterium tumefaciens strains carrying octopine Ti-plasmids after wounding of GA3 elongated stems or of hypocotyls. Tumors could be isolated and cultured aseptically. The tumor marker, octopine synthase (Ocs) activity, was present demonstrating the applicability of the Agrobacterium system for transfer of genetic information. For the production of transgenic plants two procedures were tested: inoculation of explants derived from cotyledons and hypocotyls of two weeks old seedlings and a leaf-disc procedure. The first method yielded both octopine positive calli as well as shoot regeneration on the six genotypes tested. In most cases, regeneration occurred from pre-existing, non-transformed meristems. The presence of Ocs activity could not be demonstrated in these shoots, although in one case octopine positive callus was formed at the base of the shoot, suggesting a chimeric structure of the plantlet or T-DNA genes, which were silent within the shoot and became active again in proliferating callus. The leaf-disc method did not give rise to direct or indirect regeneration, but transformed callus proliferated on the leaf edges. Optimal transformation frequencies were dependent on B. vulgaris genotype and Agrobacterium strain. The use of Agrobacterium shooter mutants or strains carrying an isolated cytokinin gene in order to influence endogenous phytohormone ratios did not result in the formation of shoots nor did it increase levels of regeneration in the first method. Further optimization is in order and in progress.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00043382
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