A new efficient method for rapid in-vitro shoot regeneration on leaf explants of Poplar 741

In the experiments of Agrobacterium tumefaciens-mediated transformation of the hybrid poplar 741, Populus alba (P. davidiana ×P. simonii) ×P. tomentosa, we developed a rapid and efficient method of shoot regeneration from the leaf explants in-vitro on Murashige and Skoog (MS) medium. The leaf explant segments was first cultured on medium I (MS medium supplemented with 0.5 mg/L of BA and 1.0 mg/L of 2,4-D ) for 2～3 days and then transferred to medium SH (MS medium containing 2.0 mg/L of BA and 0.1 mg/L of NAA) to culture for 10 days. 86.7% of leaf segments produced shoots after the leaf segments were transferred from medium SH to medium II (MS medium with 0.5 mg/L of BA) for 1 week. The average shooting number was 40～50 per 1 cm×1 cm of leaf segment. However, if the leaf explants incubated on medium I longer than 5 days, they produced more roots instead of shoots.