Saving rainforests in the South Pacific: Challenges in ex situ conservation

Rainforests in the South Pacific hold a considerable amount of plant diversity, with rates of species endemism > 80% in some countries. This diversity is rapidly disappearing under pressure from logging, clearing for agriculture or mining, introduced pests and diseases and other anthropogenic sources. Ex situ conservation techniques offer a means to limit the loss of plant diversity. Seed banking is considered the most efficient and cost effective of these techniques but is applicable only to seed capable of tolerating desiccation and cold storage. Data on the degree of tolerance of these conditions was lacking for more than half of the 1503 South Pacific rainforest genera examined for this review. Of the 710 genera for which data were available, the storage behaviour of 324 was based on an assessment of only one or two species, although 76% of those genera contained at least 10 species. Many of the unstudied or poorly studied genera are shared across several South Pacific nations, providing an excellent opportunity for collaboration on future ex situ research and conservation. Of the 386 genera for which three or more species have been studied, 343 have a very high proportion of species ( > 95% of those tested) that are suitable for seed banking. Seed banking could therefore provide a suitable means for preserving a large proportion of the rainforest flora before it becomes extinct in the wild. Alternatives for preserving species that are not suitable for seed banking are also discussed

Current issues in plant cryopreservation and importance for ex situ conservation of threatened Australian native species

© 2019 CSIRO. An alarming proportion of Australia's unique plant biodiversity is under siege from a variety of environmental threats. Options for in situ conservation are becoming increasingly compromised as encroaching land use, climate change and introduced diseases are highly likely to erode sanctuaries regardless of best intentions. Ex situ conservation is currently limited to botanic garden living collections and seed banking, with in vitro and cryopreservation technologies still being developed to address ex situ conservation of species not amenable to conventional storage. Cryopreservation (storage in liquid nitrogen) has been used successfully for long-term biosecure storage of shoot tips of several species of threatened Australian plants. We present a case for building on this research and fostering further development and utilisation of cryopreservation as the best means of capturing critical germplasm collections of Australian species with special storage requirements (e.g. recalcitrant-seeded taxa and species with short-lived seeds) that currently cannot be preserved effectively by other means. This review highlights the major issues in cryopreservation that can limit survival including ice crystal damage and desiccation, toxicity of cryoprotective agents, membrane damage, oxidative stress and mitochondrial function. Progress in understanding and mitigating these stresses is vital for advancing cryopreservation for conservation purposes

Trading populations—can biodiversity offsets effectively compensate for population losses?

Biodiversity offsetting promotes the protection or restoration of biodiversity at one site to compensate for the loss of biodiversity due to development at another site. Thus populations of species at a development site may be extirpated in the belief that offsetting elsewhere will compensate for the loss of biodiversity. In this study we tested the replaceability of roadside populations of the orchid Diuris platichila threatened by development (populations 1-5, n = 50-541 plants) with a potential offset population occurring in nearby natural vegetation (population 6, n = 143 plants). We measured differences in habitat among the populations and associated differences in flowering and fruiting. We also measured genotypic diversity within and among the populations, and the capacity of soil from each population to promote the symbiotic germination of outcrossed seed from the two largest populations (populations 1-2). An evaluation of the performance of the relevant offset policy was also undertaken which was informed by these studies. Compared to the roadside populations, the potential offset site had limited flowering (except after fire) and was genotypically less diverse. Soil from the potential offset site, and populations 2, 3 and 5, supported significantly less seed germination than soil from population 1. Translocating individuals from the most genotypically diverse populations into the offset population could help to buffer against the loss of genetic diversity if offsetting was required; however, the limited reproduction and recruitment opportunities at the offset site could result in the eventual erosion of any initial increase in diversity. The offset policy failed to secure a suitable offset for a hypothesized loss of plants. More generally we conclude that offsetting approaches which do not assess genotypic diversity and recruitment capacity may fail in their objective of protecting species and that maintaining populations in safe sites may be required

A cryopreservation protocol for ex situ conservation of terrestrial orchids using asymbiotic primary and secondary (adventitious) protocorms

© 2015, The Society for In Vitro Biology. In a bid to better conserve endangered terrestrial orchids, we detail cryogenic research using a widely distributed terrestrial orchid, Caladenia latifolia, as a model species for development of cryopreservation for primary (seed generated) and secondary (adventitious) protocorms. Primary protocorm cryopreservation (using droplet vitrification) involved a number of experimental lines of inquiry: investigation of a suitable plant vitrification solution (PVS) by comparing three variants of a standard PVS (2, 3 and 4), determining the most suitable primary protocorm developmental stage for successful cryopreservation, testing the effectiveness of a preculture medium treatment prior to cryopreservation, and investigating temperature preconditioning at the preculture stage as well as different components of the recovery medium. Primary protocorms were generated using asymbiotic in vitro germination media developed by the authors specifically for the test species (half-strength MS macroelements and microelements with 5% (v/v) fresh filter sterilized coconut water). Secondary protocorms were propagated using an in vitro proliferation medium (½ MS with 5 µM a-naphthaleneacetic acid + 2 µM 6-benzylaminopurine). A modified preconditioning step was developed, involving incubation on ½ MS with 0.2 M raffinose for 48 h at 15°C instead of 20°C. The standard recovery medium (½ MS 1 µM zeatin + 0.5 µM gibberellic acid) was replaced after the first week following warming from liquid nitrogen (LN), with asymbiotic germination medium (½ MS + 5% (v/v) coconut water) for the remainder of the recovery phase. This new step increased the survival of primary protocorms from 68 to 85%. The average post-cryostorage regeneration of plants from primary protocorms increased from 17 to 48% after a 6-wk incubation. A similar protocol increased the survival of secondary protocorms from 63 to 84%. Regeneration of plants from secondary cryostored protocorms increased from 11 to 26% after 14 wk. The protocols developed here provide a useful template for advancing cryoconservation of other orchid taxa, particularly rare and threatened species