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Seed banking of rainforest species is hindered by lack of knowledge as to which species are tolerant of desiccation and freezing. We assessed 313 Australian rainforest species for seed banking suitability by comparing the germination percentage of fresh seeds to seeds dried at 15% RH and seeds stored at −20 °C after drying. We then compared desiccation responses to environmental, habit, fruit and seed characteristics to identify the most useful predictors of desiccation sensitivity. Of 162 species with ≥ 50% initial germination, 22% were sensitive to desiccation, 64% were tolerant and 10% were partially tolerant; the responses of 4% were uncertain. Of 107 desiccation tolerant species tested for response to freezing, 24% were freezing sensitive or short-lived in storage at −20 °C. Median values for fresh seed moisture content (SMC), oven dry weight (DW) and the likelihood of desiccation sensitivity (PD-S) were significantly greater for desiccation sensitive than desiccation tolerant seeds. Ninety-four to 97% of seeds with SMC < 29%, DW < 20 mg or PD-S < 0.01 were desiccation tolerant. Ordinal logistic regression of desiccation response against environmental, habit, fruit and seed characteristics indicated that the likelihood of desiccation sensitivity was significantly increased by a tree habit, fleshy fruit, increasing fresh SMC and increasing PD-S. The responses observed in this study were combined with earlier studies to develop a simple decision key to aid prediction of desiccation responses in untested rainforest species.

Background and Aims Knowledge of the evolutionary processes responsible for the distribution of threatened and highly localised species is important for their conservation. Population genomics can provide insights into evolutionary processes to inform management practices, including the translocation of threatened plant species. In this study, we focus on a critically endangered eucalypt, Eucalyptus sp. Cattai, which is restricted to a 40 km 2 area of Sydney, Australia and is threatened by increased urbanisation. Eucalyptus sp. Cattai is yet to be formally described in part due to its suspected hybrid origin. Here, we examined evolutionary processes and species boundaries in E. sp. Cattai to determine whether translocation was warranted. Methods We used genome-wide scans to investigate the evolutionary relationships of E. sp. Cattai with related species, and to assess levels of genetic health and admixture. Morphological trait and genomic data were obtained from seedlings of E. sp. Cattai propagated in a common garden to assess their genetic provenance and hybrid status. Key Results All analyses revealed that E. sp. Cattai was strongly supported as a distinct species. Genetic diversity varied across populations, and clonality was unexpectedly high. Interspecific hybridisation was detected, and was more prevalent in seedlings compared to in situ adult plants, indicating that post-zygotic barriers may restrict the establishment of hybrids. Conclusions Multiple evolutionary processes (e.g., hybridisation and clonality) can operate within the one rare and restricted species. Insights regarding evolutionary processes from our study were used to assist with the translocation of genetically ‘pure’ and healthy ex situ seedlings to nearby suitable habitat. Our findings demonstrate that it is vital to provide an understanding of evolutionary relationships and processes with an examination of population genomics in the design and implementation of an effective translocation strategy.

We investigated ex situ conservation options for two Australian rainforest species severely affected by myrtle rust in the wild -Rhodamnia rubescens (Benth.) Miq. and Rhodomyrtus psidioides (G.Don) Benth. Both species were successfully initiated into tissue culture though the rate of contamination was high and not significantly improved by the disinfection techniques tested. Explants surviving initiation grew well on Murashige and Skoog medium (MS; pH 6.0) with 30 g L À1 sucrose, 1 mM benzyl adenine and 0.2 mM indole-3-butyric acid. Culture of R. rubescens for eight weeks on MS with 0, 5, 10 or 20 mM indole-3-butyric acid resulted in root production for some plantlets, and successful transfer to potting mix; no significant differences in root production among treatments were detected. Both species were successfully propagated by semi-hardwood cuttings with strike rates of 0-67% for R. rubescens and 0-75% for R. psidioides. For R. rubescens, pretreatment of cuttings with Zaleton Ò and incubation in Preforma Ò plugs reduced the time to root development and significantly improved the strike rate (P ¼ 0.001). R. rubescens seed proved to be orthodox and suitable for standard seedbanking; R. psidioides seed proved to be freezing sensitive but suitable for storage at 48C. As the two species now produce few viable seeds in the wild, however, conservation by seedbanking will first require the establishment of a seed orchard from vegetatively propagated plants. We recommend swift action to conserve species in the Pacific similarly affected by myrtle rust before their growth and reproductive capacity are seriously diminished.

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