Establishment of highly efficient and reproducible Agrobacterium-mediated transformation system for tomato (Solanum lycopersicum L.)

A simple and improved Agrobacterium-mediated transformation protocol of tomato (Solanum lycopersicum) cultivar Rio Grande was developed to inspect the potential of producing transgenic tomatoes. In this study, regeneration and transformation efficiency as assessed in response to the seedling age, explant type, co-infection, co-cultivation duration, selection pressure (kanamycin), and the optimal concentration of plant growth regulators (PGR) 6-benzylaminopurine (BAP), gibberellic acid (GA3), and indolebutyric acid (IBA) in a Murashige and Skoog (MS) basal medium. To accomplish this goal, 2- to 4-wk-old tomato explant cotyledons, hypocotyl, and cotyledonary nodes were excised and transformed with the EHA105 Agrobacterium tumefaciens strain harboring pBIN19 binary vector containing uidA reporter gene and nptII as a selectable marker. Results revealed that 14-d-old cotyledonary nodes and leaves inoculated for 15 min with A. tumefaciens strain EHA105 following 48-h co-cultivation were optimal for the highest percent transformation efficiency 27.31. Antibiotic kanamycin (Kan) at 25 mg L−1 in the regeneration selection medium was found to be effective. MS medium containing optimal concentrations of 1.5 mg L−1 of BAP, 0.2 mg L−1 GA3, and IBA 1.5 mg L−1 showed a significant level of percent regeneration, shoot elongation, and rooting efficiency of transformed plantlets. Molecular analysis of T0 transgenic tomato plants showed integration and a higher relative expression level of the uidA gene. The optimized A. tumefaciens–mediated transformation method for tomato cultivar Rio Grande showed the highest percent transformation efficiency (TE) and regeneration efficiency (RE) and is likely to give consistent results with different tomato cultivars.