Studies on Agrobacterium tumefaciens mediated genetic transformation of watermelon

Several factors affecting Agrobacterium tumefaciens-mediated gene transformation of watermelon were studied by using the transient expression of GUS as criteria. The results showed that Hygromycin at 15 mg/L can be used to screen the cotyledon of watermelon after transformation; Cefotaxime at 500 mg/L can be used to eliminate Agrobacterium tumefaciens; Agrobacterium strain EHA105 had the strongest virulence to watermelon among three strains (AGL-1; LBA4404 and E-HA105) used in the experiment; Co-culture for 3-4 days not only had higher GUS transient expression but also could avoid Agrobacterium staining; The bacterial concentration of OD600=0.3 was the best inoculum density and 10 minutes was the best inoculum time; It was beneficial to add acetosyringone into cocultivation medium for improving transformation frequency.