The influence of different antibiotic treatments in soybean genetic transformation was evaluated. First, an assay was performed to verify how different antibiotic treatments affect soybean embryogenic tissues. The effect of carbenicillin at 500 mg L-1 was genotype-dependent. This antibiotic did not affect embryo survival of cv. IAS5, but a three-fold increase of embryo proliferation was observed for cv. Bragg, when compared to the control. On the other hand, cefotaxime at 350 and 500 mg L-1 caused death of embryogenic tissues of both cultivars. Finally, the association of cefotaxime (250 mg L-1) + vancomycin (250 mg L-1) did not affect negatively the somatic embryos of tested cultivars until 63 days of treatment. Thereafter, a second experiment was carried out to determine the efficacy of different antibiotic treatments in suppressing LBA4404 Agrobacterium tumefaciens strain in genetic transformation. On tissue culture conditions, carbenicillin at 500 and 1000 mg L-1 was not active against Agrobacterium. On the other hand, treatments with cefotaxime at 350 and 500 mg L-1, and cefotaxime + vancomycin efficiently suppressed Agrobacterium during 49 days. Data of both experiments suggested cefotaxime + vancomycin for 49-63 days as the most appropriate treatment. This is the first work reporting the effect of antibiotics on soybean tissues. By identifying an antibiotic combination that suppressed A. tumefaciens with minimal phytotoxic effects, we are able to recommend it for improvement of soybean Agrobacterium-mediated transformation procedure.
Agrobacterium tumefaciens; carbenicillin; cefotaxime; genetic transformation; Glycine max; vancomycin
