An improved Agrobacterium tumefaciens mediated transformation of Artemisia annua L. by using stem internodes as explants

Transformation of Artemisia annua, which produces the sesquiterpenoid endoperoxide artemisinin widely used for the treatment of malaria, has been hampered by the low efficiency of adventitious shoot and root formation on a selective medium containing additional compounds for Agrobacterium decontamination. Here we identified several factors which were all shown to be of importance for optimization of Artemisia annua transformation. Results indicated that stem internodes showed better resistance capacity to Agrobacterium decontaminator than leaves did. Agrobacterium tumefaciens with an optical density (OD) value of 0.2–0.5 plus 100 μmol of acetosyringone per litre of solution gave the best transformation efficiency. Moreover, kanamycin at 30 mg/l in the culture medium was effective in suppressing the growth of non-transformed tissue. Furthermore, transgenic shoots required an early induction of rooting. In addition, dimethyl sulphoxide considerably improved the rooting of shoots. The present work provides rapid and reproducible transformation and regeneration of A. annua.