Shoot organogenesis and plant regeneration from stem explants in Acer truncatum

Acer truncatum is an economically important multipurpose tree in China due to its high values in ornamental, ecology, oil-production and medicine. The lack of reliable and stable in vitro regeneration system seriously restricts its breeding and industrial development. This study first presented a protocol for in vitro regeneration of A. truncatum via de novo shoot organogenesis from stem explants. The results showed that sterilization, basal medium, plant growth regulators and light condition significantly influenced shoot regeneration of A. truncatum . The best sterilization protocol for stem explants was 75% ethanol (30 s) + 0.1% HgCl ₂ (10 min ), with a lowest contamination rate (4.74%). The highest callus induction rate (97.17%) was achieved when stem segments were cultured on WPM medium with 0.2 mg/L 2,4-D and 0.5 mg/L 6-BA in the dark for 15 days. The optimal shoot differentiation rate (10.51%) was obtained when callus was cultured on NN69 medium containing 0.5 mg/L CPPU. The rooting rate of adventitious shoots was achieved 85% by using NN69 medium with 0.25 mg/L IBA, and the rooted seedlings were transplanted into pots containing a mixture of peat, perlite and vermiculite (2:1:1, v:v:v), the survival rate was more than 80%. Histological analysis demonstrated the origin and development process of indirect shoot organogenesis, including callus formation, meristematic nodule formation and shoot differentiation. This study will be beneficial to the germplasm conservation, mass propagation and genetic improvement of A. truncatum .