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.

In vitro Ploidy Manipulation for Crop Improvement

“…For example, Hussey and Hypher (1978) documented cytochimeral sugar beets after treatment with colchicine and observed that polyploid cells disappeared over subsequent subcultures. Similarly, Lattier et al (2013) found that for Acer platanoides, mixoploid tissues reverted to diploids over a 6-month period.…”

“…If all the initial cells are not affected, mixoploids or cytochimeras may form. Mixoploids have been widely observed in in vitro chromosome doubling of a wide range of species, including; Acer platanoides (Lattier et al, 2013), Helleborus sp. (Dhooghe et al, 2009b), Hypericum sp.…”

“…The wide success of colchicine as an antimitotic inhibitor has led to its continued and regular use in more recent studies, for example Bletilla striata (Pan-pan et al, 2018), Petuna axillaris (Regalado et al, 2017), and Populus hopeiensis (Wu et al, 2020). In comparison, oryzalin has been used successfully to create polyploid lines of woody and semi-woody plants including Rosa (Kermani et al, 2003), Rhododendron (Hebert et al, 2010), Chaenomeles (Stanys et al, 2006), Hypericum (Meyer et al, 2009), and Acer platanoides (Lattier et al, 2013; Table 1). Further, oryzalin has been shown to be more efficient than colchicine for in vitro chromosome doubling for Chaenomeles japonica (Stanys et al, 2006), Rhododendron sp.…”

“…Plant growth regulators may also interact with antimitotic agents. Lattier et al (2013) showed the addition of the cytokinin 6-benzyl amino purine (BA) to medium containing oryzalin increased shoot mortality at higher oryzalin concentrations. They suggested that BA may act to increase cell cycling, producing cells that more quickly transition from metaphase to anaphase where they may be susceptible to oryzalin (Lattier et al, 2013).…”

“…Lattier et al (2013) showed the addition of the cytokinin 6-benzyl amino purine (BA) to medium containing oryzalin increased shoot mortality at higher oryzalin concentrations. They suggested that BA may act to increase cell cycling, producing cells that more quickly transition from metaphase to anaphase where they may be susceptible to oryzalin (Lattier et al, 2013). Considering media components when developing in vitro ploidy manipulation protocols may maximize chromosome doubling efficiencies.…”