Transgenic bialaphos-resistant snapdragon (Antirrhinum majus L.) produced by Agrobacterium rhizogenes transformation

Transgenic herbicide-resistant snapdragon (Antirrhinum majus L.: Scrophulariaceae) plants were obtained by co-cultivation of leaf explants with Agrobacterium rhizogenes harboring Ri plasmid and pARK5. The T-DNA region of pARK5 contains bar gene encoding phosphinothricin acetyltransferase under the control of the cauliflower mosaic virus 35S promoter, and nptII gene encoding neomycin phosphotransferase II under the control of nopaline synthase promoter. Transformed hairy roots induced from leaf explants inoculated with A. rhizogenes strain A13 (pARK5) could grow on 1 mg l(-1) bialaphos-containing half-strength MS medium, although hairy roots transformed by the wild type strain of A. rhizogenes A13 could not survive at the same concentration of bialaphos. Shoot regeneration from the hairy roots integrating T-DNA of pARK5 was also stimulated at 1 mg l(-1) bialaphos. Regenerated shoots readily developed roots on 2 g l(-1) gellan gum solidified half-strength MS medium. The transgenic nature of the plants was confirmed by opine, PCR and Southern analyses. Regenerated plantlets were successfully established in the growth chamber. Acclimatized plants exhibited altered phenotypes known as Ri syndrome such as reduced apical dominance with highly branched stems and short internodes, and also showed resistance to an applied standard level of commercial herbicides. (C) 1998 Elsevier Science B.V. All rights reserved.