Ex situ collections hold the key

Dr Emma Dalziell (Research Scientist), Dr David Merritt (Research Scientist), Dr Bryn Funnekotter (Research Scientist), Dr Eric Bunn (Research Scientist)

Ex situ conservation, the conservation of species and their genetic diversity ‘off-site’ or away from the natural habitat, is a core function of many botanic gardens.

Ex situ conservation encompasses a range of techniques and technologies to collect, store, study and use plant material.

At Kings Park, ex situ conservation has been undertaken since the 1960s, when the seed bank was established to support the creation of the Botanic Garden. Today, the ex situ conservation programs include seed banking, tissue culture, cryopreservation and plant collections within the display gardens.

Ex situ conservation is an important strategy to prevent the loss of biodiversity from a myriad of threats in the plant’s natural habitat. It also plays a major role in supporting ecosystem restoration and rare species translocations.

Genetically and geographically representative collections of seeds can be sourced and banked over many years to build sufficient stocks for restoration.

Inside the Western Australian Seed Centre vault at Kings Park where the seeds of 3,800 Western Australian native species are stored at -20°C. Photo: Dave Blumer

Plants grown from seeds or vegetatively through tissue culture can be used as founder material to develop seed orchards where seed supplies are limited.

The collections provide opportunities to research plant biology, propagation and establishment requirements, pests and disease resilience, climate change resilience and adaptation, and many other factors that contribute to restoration success.

The largest ex situ collections are held in the seed bank of The Western Australian Seed Centre. Seeds are sourced from across WA, including locally, where seeds assist bushland restoration in Kings Park and Bold Park. More than 300 of these bushland species are stored in the seed bank and are used for urban bushland restoration.

Seed collecting in the Pilbara. Kings Park staff travel far and wide to collect seeds to support conservation and restoration projects. Photo: Luke Sweedman

Kings Park has worked for more than 20 years as part of national and international collaborative conservation initiatives through the Australian Seed Bank Partnership and the Millennium Seed Bank Partnership. These partnerships have resulted in collections of more than 2000 WA species, with most duplicated at the Millennium Seed Bank in the Royal Botanic Gardens, Kew.

The tissue culture collection houses 47 rare and threatened species with more than 200 clonal accessions capturing some of the genetic diversity. This collection began in 1982 and has close to a thousand collections with a hundred species successfully initiated into tissue culture.

The Grevillea scapigera collection (See page 16) is of particular importance to translocation where 25 different accessions of this threatened species were collected. The tissue culture collection supports species conservation and restoration, with collections made from a wide range of genera, including the carnivorous species Aldrovanda vesiculosa.

Examples of the threatened species growing in the tissue culture collection. Top row – Acacia leptoneura, Aldrovanda vesiculosa, Banksia montana, Darwinia masonii. Middle row – a shelf including Hakea aculeata. Bottom row – Eremophila pinnatifida, and Symonanthus bancroftii, with an image of the tissue culture room. On the right – a flowering specimen of Grevillea scapigera. Photos: Bryn Funnekotter

Water wheel plant (Aldrovanda vesiculosa) a small aquatic carnivorous plant is maintained in liquid medium in tissue culture. Photo: Bryn Funnekotter

Cryopreservation (storage of plants in liquid nitrogen, temperatures below -130°C) provides a long-term conservation option for these species in tissue culture, as well as a backup for collections in the seed bank. Cryopreservation collections began in 1992 and now include collections of seed, shoot tips from tissue culture material and symbiotic fungi for the orchid collection.

Ex situ methods provide an important component of plant conservation and restoration, however, our knowledge of how plant material responds to ex situ storage conditions is still limited due to the number and diversity of our native flora.

Our current and future research, including a four-year Australian Research Council grant with financial support from the Friends of Kings Park Fund, aims to understand seed storage performance and to develop new technologies that will assist in the early identification of problematic seed collections and establish alternative methods of storage to increase their lifespan.

This work will contribute to ensuring that seeds remain healthy and useful for restoration programs in the decades, or centuries, to come.

The stats

3800+ species stored ex situ at Kings Park

~25% of the total flora of WA

~15,000 packets of seed

985 jars in tissue culture

1209 vials in ultra-low temperature cryogenic storage

293 species in cryogenic storage

164 threatened species from WA

47 species of conservation significance in tissue culture

400+ eucalyptus species stored in the seed vault (-20°C)

300+ Western Australian acacia species stored in the seed vault (-20°C)

60+ summer scholarship, honours and postgraduate students in the last 20 years