Agrobacterium-mediated transformation of broad bean Vicia faba L.

Three broad bean cultivars, which varied in morphology and geographical origin, were inoculated with nine Agrobacterium strains to determine the best combination for potential use in transformation and to investigate the possibility of regenerating genetically transformed plants. The stems of seedlings were inoculated with A. tumefaciens wild type strains (A281 and B6S3), transconjugant strains (C58C1(pArA4abc) and C58C1(pArA4b)), the B6S3 rooty and shooty mutants (GV3101(pGV2255), GV3101(pGV2215) and GV3101(pGV2235)), and A. rhizogenes wild type strains (8196 and 15834). With all the tested strains only unorganized tumour tissue was obtained. Cultivars differed in their susceptibility to bacterium strains, and plant genotype vs. strain interaction was detected. The strain most virulent to cv. Lobab Lippoi was C58C1(pArA4b), while with the less susceptible cvs. Topolo and Oslje the best results were obtained with strains A281 and B6S3, respectively. However, the size and phenotype of tumours depended on the bacterial strain exclusively, indicating that the difference in transformation efficiency of each bacterial strain might be the result of a different efficiency in one or more of the steps prior to expression of T-DNA genes within each particular cultivar. Established tumorous calli grown on hormone-free MS medium showed enhanced peroxidase activity. The in vitro transformation of cotyledon, leaf and internodal stem segments with Ri plasmids containing bacterium strains, was not successful.