Tissue Culture Innovations for Propagation and Conservation of Myrteae-A Globally Important Myrtaceae Tribe.

Myrteae is the most species-rich tribe in the Myrtaceae family, represented by a range of socioeconomically and ecologically significant species. Many of these species, including commercially relevant ones, have become increasingly threatened in the wild, and now require conservation actions. Tissue culture presents an appropriate in vitro tool to facilitate medium-term and long-term wild germplasm conservation, as well as for commercial propagation to maintain desirable traits of commercial cultivars. So far, tissue culture has not been extensively achieved for Myrteae. Here, tissue culture for Eugenia, one of the most species-rich genera in Myrteae, is reviewed, giving directions for other related Myrteae. This review also focuses on ex situ conservation of Australian Myrteae, including using seed banking and field banking. Despite some progress, challenges to conserve these species remain, mostly due to the increasing threats in the wild and limited research. Research into in vitro methods (tissue culture and cryopreservation) is paramount given that at least some of the species are 'non-orthodox'. There is an urgent need to develop long-term in vitro conservation for capturing the remaining germplasm of threatened Myrteae.

Tissue culture tools for selenium hyperaccumulator Neptunia amplexicaulis for development in phytoextraction.

Neptunia amplexicaulis is an herbaceous legume endemic to the Richmond area in central Queensland, Australia and is one of the strongest known Selenium hyperaccumulators on earth, showing significant potential to be utilised in Se phytoextraction applications. Here a protocol was established for in vitro micropropagation of Se hyperaccumulator N. amplexicaulis using nodal segments from in vitro-germinated seedlings. Shoot multiplication was achieved on Murashige and Skoog (MS) basal media supplemented with various concentrations of 6-Benzylaminopurine (BA) (1.0, 2.0, 3.0 mg L-1) alone or in combination with low levels of Naphthaleneacetic acid (NAA) (0.1, 0.2, 0.3 mg L-1), with 2.0 mg L-1 BA + 0.2 mg L-1 NAA found to be most effective. Elongated shoots were rooted in vitro using NAA, with highest root induction rate of 30% observed at 0.2 mg L-1 NAA. About 95% of the in vitro rooted shoots survived acclimatization. Clonally propagated plantlets were dosed with selenate/selenite solution and assessed for Se tissue concentrations using Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES) and found to retain their ability to hyperaccumulate. The protocol developed for this study has potential to be optimised for generating clonal plants of N. amplexicaulis for use in research and phytoextraction industry applications.