Micropropagation and Polyploid Induction of Acer platanoides ‘Crimson Sentry

Abstract

Protocols were developed for micropropagation and induction of autopolyploids in a fastigiate cultivar of Norway maple (A. platanoides L. ‘Crimson Sentry’). Murashige and Skoog (MS) medium, woody plant medium (WPM), and Quoirin and Lepoivre medium were supplemented with 2 μM 6-benzylaminopurine (BA), meta-Topolin, 6-(γ,γ-dimethylallylamino) purine, kinetin, or thidiazuron to evaluate microshoot proliferation. Murashige and Skoog medium with 2 μM BA yielded the most microshoots (3.2) and longest microshoots (30.6 mm) per subsample after 5 weeks. The influence of BA concentration on proliferation was evaluated at 0, 2, 4, 8, or 16 μM. Optimal multiplication rate was achieved at 2 or 4 μM BA producing approximately 2.8 microcuttings per subsample after 5 weeks. To induce in vitro rooting, half-strength WPM was supplemented with 0, 5, 10, 20, 40, or 80 μM indole-3-butyric acid (IBA). Optimal in vitro rooting (70%), number of roots (2.5), and root length (15 mm) per subsample were achieved with 10 μM IBA after 8 weeks. To induce polyploidy, microcuttings were pretreated for 7 days on MS medium with 4 μM BA alone or combined with 1 μM IBA, indole-3-acetic acid (IAA), or 1-naphthaleneacetic acid prior to treatment in liquid MS medium containing 15 μM oryzalin for 3 days. Homogenous tetraploids were only obtained from shoots pretreated with IAA. This research provides optimized protocols for micropropagation and autopolyploid induction of A. platanoides ‘Crimson Sentry’ and demonstrates the development of tetraploid lines for use in future improvement programs.