Use of phosphomannose isomerase-based selection system for <Emphasis Type="Italic">Agrobacterium</Emphasis>-mediated transformation of tomato and potato

Two selection systems for Agrobacterium tumefaciens mediated transformation of tomato and potato were compared. In the tomato (Lycopersicon esculentum cv. Moneymaker), the highest transformation rate, 4.2 %, of cotyledon explants on mannose-selection medium was obtained when mannose/sucrose concentration in the regeneration medium was 5/15 g dm⁻³. The best transformation efficacy with the commonly used concentration of 100 mg dm⁻³ kanamycin as a selection agent was 9 %. In the potato (Solanum tuberosum cv. Bintje), the highest transformation frequency was 53.3 % when mannose concentration in the regeneration medium was 5 g dm⁻³ during the first 3 weeks after transformation and 10 g dm⁻³ afterwards. The optimum concentration of sucrose was 20 g dm⁻³. The transformation efficiency using kanamycin as a selection agent at a concentration 100 mg dm⁻³ was 33.3 % with potato. Our results demonstrate that the transformation efficiency using mannose selection is 1.6-fold higher for potato and about 2 times lower for tomato comparing with the ordinary protocol using kanamycin.