Agrobacterium-mediated transformation of watermelon (Citrullus lanatus)

Transformation of watermelon (Citrullus lanatus cv. Zaojia) using Agrobacterium tumefaciens strain EHA105 containing the plasmid pRD400 carrying Pti4 gene was studied in this work. Proximal cotyledons as explants were pre-cultivated for two day in the dark and it was found that the best condition for transformation of watermelon was the use of bacteria at a concentration of OD600 0.3, inoculation for 10 min and 72 h of co-cultivation. Kanamycin as a selective agent in different concentration (75, 100 and 125 mg/l) was tested. Transformed explants on medium supplemented with 100 mg/l kanamycin received a higher efficiency of shoots with transgenic DNA (9.17%). Using specific primer to Pti4 gene, PCR product with a size of 680 bp was amplified when the genomic DNA extracted from the transformants were used as templates. A total of 148 plants with percentage 10.28% showed positive results using PCR analysis and subsequently all were regenerated into whole plants.Key words: Watermelon (Citrullus lanatus Thumb), transgenic, Agrobacterium tumefaciens, in vitro