A combination of overgrowth-control antibiotics improves Agrobacterium tumefaciens-mediated transformation efficiency for cultivated tomato (L. esculentum)

Summary The transformation efficiency of cultivated tomato (Lycopersicon esculentum cv. UC82) using Agrobacterium tumefaciens was improved from 14% in a previous report to 25% in the present study. Several variables potentially involved in the improvement of transformation efficiency were evaluated, including enhancements in the regeneration system, antibiotics used for Agrobacterium-overgrowth control, and method of applying kanamycin for selection. The most important variable identified was the influence of overgrowth-control antibiotics on both the regeneration response and transformation efficiency. The best transformant recovery and Agrobacterium-overgrowth control was obtained using 250 mg l⁻¹ claforan and 250 mg l⁻¹ ticareillin as the overgrowth-control antibiotics in the media. Selfed T₁ progeny plants showed Mendelian inheritance ratios in 77% of the independently transformed lines according to phenotype expression [β-glucuronidase (GUS) assay results], and confirmed by polymerase chain reaction amplification of the transgene in progeny.