In vitro culture has enabled a variety of recalcitrant and threatened plant taxa to be micropropagated in the absence of viable conventional propagation methods. Cryogenic storage research has provided alternative protocols for efficient long-term germplasm storage for many plant species. Recent advances in tissue-culture methods such as somatic embryogenesis have enabled the production of >20 000 somatic embryos of a recalcitrant native Australian rush in a few months, far higher than other in vitro methods for these types of plants. Cryogenic protocols are reported for >30 species of Australian vascular plants, seed and numerous mycorrhizal fungi (mainly orchid spp.), greatly extending the range and type of material that can be stored through the application of cryogenic methods. The role of in vitro and cryogenic research initiatives in botanic gardens for plant biodiversity conservation and restoration is discussed, using examples of successful ex situ conservation through tissue-culture and cryogenic-storage research.

Rushes are important understorey species and comprise a significant component of pre-mined ecosystems. Re-establishment of rushes into disturbed sites has often been problematic. Several cytokinins and thidiazuron were investigated for the stimulation of somatic embryogenesis in key members of the Restionaceae. Somatic embryogenesis was observed for Desmocladus flexuosus (R.Br.) B.G.Briggs & L.A.S.Johnson with benzyladenine (BA) at 1, 5 or 15 μM alone and 1 μM 2,4-dichlorophenoxyacetic acid (2,4-D). The response to zeatin (Z) and 2iP-6-γ-γ-dimethyl-allyamino-purine (2iP) was negligible. For Baloskion tetraphyllum (J.J.H. de Labillardiere) B.G.Briggs & L.A.S.Johnson and Lyginia imberbis R.Br., BA, Z and 2iP were ineffective in stimulating any response.Somatic embryogenesis was achieved for B. tetraphyllum on 1/2-strength Murashige Skoog (1/2 MS) + 1 μM 2,4-D, with an estimated 14 000 somatic embryos produced from 1 g of plant material. All somatic embryos converted into plantlets and were successfully transferred to soil.Investigation of thidiazuron (TDZ) at 5 and 10 μM and 1 μM 2,4-D demonstrated that young coleoptiles (5–7 days) of B. tetraphyllum produced significantly more somatic embryos (168-fold more) than did older coleoptiles (>14 days). For D. flexuosus, leaf basal portions produced somatic embryos on 5 and 10 μM TDZ, and 5 μM TDZ + 1 μM 2,4-D. Proliferation of 'secondary somatic embryos' was also successful when somatic embryos were initiated on 10 μM TDZ and transferred to 1/2 MS (~9-fold increase).This study demonstrated variation in response among species of the same family, with D. flexuosus responding to BA and TDZ and B. tetraphyllum responding only to 2,4-D. The protocol investigated has the potential to be commercially viable with over 14 000 somatic embryos produced in 6 weeks for B. tetraphyllum.

Many species of Western Australian Cyperaceae (sedges) are vital components of the indigenous flora but commonly display low seed set, poor seed quality and intractable seed dormancy. We report the effects of incubation temperature and in vitro growth media on whole seed germination compared with extracted zygotic embryo growth in Tetraria capillaris, T. octandra, Lepidosperma drummondii and L. tenue. No germination was observed from intact whole seeds of all test species regardless of the treatment evaluated. In contrast, excised zygotic embryos of all study species exhibited significant increases in growth when cultured at 15°C compared to embryos incubated at 25°C; however, optimal media for embryo growth were genera specific. Extracted embryos of T. capillaris and T. octandra exhibited maximum percentage growth (30 and 40%, respectively) at 15°C on MS medium with no plant growth regulators required. In the case of L. drummondii and L. tenue 1 lM thidiazuron was a necessary addition to the MS medium resulting in 40 and 77% growth of embryos (at 15°C), respectively. Incubation of extracted embryos at 25°C (regardless of medium treatment) resulted in \10% embryo growth for T. octandra and L. tenue, while the remaining two species (L. drummondii, T. capillaris) showed no embryo growth at 25°C on any medium treatment.