EXPRESSION OF FOREIGN GENES IN SUNFLOWER (HELIANTHUS-ANNUUS L) - EVALUATION OF 3 GENE-TRANSFER METHODS

Suitable sunflower tissues and cells were transformed either by direct gene transfer into protoplasts, particle bombardment, or Agrobacteriu m co-culture. While all techniques allowed efficient short-term or tra nsient expression of the introduced gene(s) in the respective tissues, stable transformation was only observed after transformation with Agr obacterium. The latter technique was suitable for the production of tr ansgenic callus from seedling cotyledons and occasional shoots with ch imaeric expression of the transgene. Detailed analysis of the interact ion of Agrobacterium with this explant showed that infection efficienc y was critically dependent on the co-culture conditions, and that the preferentially-transformed cells were not the ones competent for regen eration.