Establishment of efficient transgenic system mediated by Agrobacterium tumefaciens in watermelon

An efficient watermelon cotyledon explant transgenic system mediated by Agrobacterium tumefaciens was established through the exploration of the factors affecting transformation efficiency of Agrobacterium tumefaciens.The parameters were optimized by measuring the efficiency of histochemical GUS transsient expression including preculture period,co-cultivation period,addition of AS and the composition of regeneration media.The watermelon cotyledon explants were pre-cultured for 2 d in the darkness,then inoculated with 0.3 of OD600 Agrobacterium tumefaciens for 10 min.Inoculated explants were co-culutred in the dark at 25℃ for 3 d,then transferred to the MS medium contained BAP(2.0 mg/L) and IAA(0.2 mg/L) plus 10 mg/L Hygromycin B and 300 mg/L cefalothin for the selection of transgenic shoots in the photoperiod of 16 h light/ 8 h dark at 25℃.