Transformation ofAntirrhinum majususingAgrobacterium rhizogenes

Hairy roots were produced following the co-cultivation of Agrobacterium rhizogenes cells with hypocotyls of five varieties of Antirrhinum majus. The use of a strain containing a binary plasmid with T-DNA bearing the β-glucuronidase reporter gene resulted in the co-transformation of some root clones. Regeneration of shoots from hairy roots occurred only with variety Golden Monarch. Regenerated plants, some of which were GUS-positive, exhibited the abnormal morphology common among hairy root regenerants; they were dwarfed, had an altered leaf shape, a poor root system and were very delayed in their flowering. Attempts to allow segregation of the two introduced T-DNAs during crossing of primary co-transformants with wild-type plants were not successful since all GUS-positive progeny possessed the abnormal morphology. However, ‘semi-dwarf’ plants with morphology much more similar to wild-type were produced by the vegetative propagation of selected side-shoots from the transformants.