An improved protocol for the regeneration and transformation of tomato (cv Rio Grande)

An improved protocol for Agrobacterium tumefaciens-mediated transformation and regeneration of the tomato cultivar Rio Grande with Arabidopsis thaliana early flowering genes AP1 and LFY has been developed. The effect of different factors on the efficiency of regeneration as well as transformation has been studied. A. tumefaciens strain EHA 105 harboring either of the binary vectors pROKIIAP1GUSint or pROKIILFYGUSint, containing APETALA 1, LEAFY (LFY), beta-glucuronidase (GUS), and neomycin phosphotransferase II (NPTII) was used for transformation. The effect of different regeneration media was studied and Murashige and Skoog (MS) medium containing Zeatin 1 mg/l and IAA 0.5 mg/l was found best, producing the highest percentage of regeneration, i.e., 30.4% and transformation, i.e., 84% (P < 0.05). The age of explants was studied and 1-week-old explants were found best producing highest regeneration (29.5%) and transformation (87.5%) values (P < 0.05). Three different types of explants were compared and best results were obtained from apical meristem explants (60.5% regeneration and 85% transformation) (P < 0.05). Transient and stable GUS expression was observed in the transgenic plants.