Abstract：Using the Agrobacterium mediated transformation method, the stem tips of Xinhai13, Xinhai14 and Xinhai16 were used as transformation acceptors for studying the effects of different seedling age, bacteria concentration, infection time and co-culture time on the efficiency of genetic transformation of stem tips, and establishing an efficient genetic transformation system of sea island cotton (Gossypium barbadense L.) in this study. The optimum transformation system was constructed as follows: the seedlings at the age of 4 d were infected by Agrobacterium tumefaciens bacteria at a concentration of OD600=0.5 for 10 min, and co-cultured for 48~72 h. The stem tips were then transformed from co-culture medium to selective medium containing 150 mg/L kanamycin for screening resistant seedlings which was transformed to rooting medium for root regeneration 25 days later. A total of 29 resistant plants were obtained from shoot-tip by grafted or directly transplanted. The PCR and RT-PCR were used to detect the resistant seedlings, and preliminary indicated that the 5- enolpyruvylshikimate-3-phosphate synthase gene (EPSPS) had been inserted into the genome of cotton. The establishment of this transformation system provides the technical support for the transgenic breeding of sea island cotton.
