In vitro propagation of Stackhousia tryonii Bailey (Stackhousiaceae): A rare and serpentine-endemic species of central Queensland, Australia

Stackhousia tryonii Bailey, a rare species which hyperaccumulates nickel and with a potential to be exploited in phytoremediation /phytomining, is difficult to propagate via seeds. This study investigated the development of a micropropagation protocol for the production of large stocks of S. ryonii. Disinfested shoot tips and nodal buds were precultured on Gamborg’s (B ) basal medium to 5 21 obtain aseptic shoots for the optimisation of the protocol. 6-Benzyl aminopurine (BAP) at 1.0 mg l produced the highest number of shoots per explant in B medium. Comparison between B and MS 5 5 media showed similar responses, but with marked influence of BAP concentration on shoot numbers. Transfer of shoots from MS (multiplication) medium to MS medium supplemented with indole-3-acetic acid (IAA) and indole-3-butyric acid (IBA), individually or in combination, indicated that a combination 21 of IAA and IBA (0.75 mg l each) is required to produce roots on young shoots (75%) compared to IBA (15–45%) or IAA (0–10%) alone. This study demonstrated that by using this protocol, a high multiplication rate (up to 18 shoots per explant) could be produced within 4 weeks, and they can be readily hardened (98% survival) in a glasshouse by transplanting them into a potting mixture of sand and perlite (4:1).