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The Australian PlantBank - Science and conservation coming together.
- How do plants grow and evolve?
- What new uses for Australian wild plants are yet to be discovered?
- How can we use plants more sustainably in horticulture and agriculture?
- With so many ecosystems under threat, how can we best act to conserve plant diversity?
Scientists at the Australian PlantBank seek to answer these questions. They study how plants grow; they develop new ways to use plants and investigate the best ways to conserve plant diversity for the future.
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Conservation in action
Without plants, life as we know it would cease to exist. The future wellbeing of all species relies on making better choices about the way we manage plants. Scientists at the Australian PlantBank study how plants germinate, grow and reproduce, and how they function within ecosystems. Other areas of research focus on how plants are adapted to their environment and evolve over time, and what causes them to die. Using this knowledge, we can begin to use plants more sustainably and preserve plant diversity in the wild.
The Wollemi pine (Wollemia nobilis) is one of the world's rarest and most threatened tree species. Until recently it was thought extinct, and the wild population is tiny - fewer than 100 adult trees. Scientists here are studying wild Wollemi pines in their natural habitat and in cultivation. Understanding how this ancient species has survived over millions of years may help us predict how it will cope with environmental challenges in the future.
Why so rare?
Fossil evidence suggests that many millions of years ago the Wollemi pine was widespread, particularly in the southern hemisphere. Over time, the environmental conditions have become much less favourable for this species; now only two small groups of trees remain in a remote canyon in Wollemi National Park. Introduced diseases, invasive weeds and frequent bushfires are likely to continue to threaten the survival of the Wollemi pine.
From the wild to the world
Rare plants can be very attractive to plant collectors. Some species have been illegally harvested and collected to extinction. To protect the small number of Wollemi pines remaining in the wild, a living collection has been established using cuttings. This collection has been used to produce plants for gardens around the world, ensuring the security of the wild plants in their natural habitat.
The survival of the Wollemi pine depends on our understanding of how they grow.
Extinction of the Wollemi pine is highly probable without scientific intervention.
Guided tours help to educate visitors about the plight of endangered species such as the Wollemi pine.
The secret life of seeds
Many plant species reproduce by seed. Seeds come in many shapes and sizes, but inside each one is a tiny embryo, surrounded by structures ensuring the greatest chance of its survival. By studying how different seeds germinate and develop into adult plants, scientists can better understand how plants regenerate and survive. This knowledge helps us to produce more plant species for horticulture and agriculture, and assists in the restoration of damaged ecosystems.
For some seeds, germination is simple; it is triggered by warmth and moisture. Other seeds have more complex needs, such as exposure to certain natural compounds or a sequence of different temperatures. To investigate the conditions needed by various plant species, seeds are germinated in the special growth chambers you can see behind this laboratory.
Some plants have seeds that remain dormant for many years. These seeds are waiting for the right conditions to germinate. For some species it is as simple as biding their time through several seasons. Other seeds may need a series of events, such as fire followed by rain. Once conditions that favour germination for each species are identified, plants are propagated by creating these conditions inside the laboratory.
All seeds must be whole and undamaged to be of value for seed-banking. Newly collected seeds are X-rayed to make sure they have an embryo which is necessary for germination. An X-ray also helps detect unwelcome visitors - insects and their larvae that devour seeds from the inside.
Inside the temperature-controlled incubators, seeds germinate in small dishes filled with agar jelly (Image: ©Richard Weinstein)
Wattle (Acacia) embryos lie dormant inside a hard black seed casing that opens after fire or other germination triggers.
Seeds of a sedge (Carex fascicularis). Whole embryos appear as lighter areas on the X-ray.
Seeds for the future
The best way to conserve plants is in their natural habitat. However, conserving plants away from the wild can be useful for research, and sometimes necessary for their survival. Seed-banking is one of the easiest and most cost-effective ways to conserve plants. Seed collections are used for research, habitat restoration and, when necessary, to reintroduce threatened species back to the wild.
Seeds must be carefully prepared for their time in the seedbank. Seed-bearing fruits are dried and their seeds are removed and cleaned to ensure that only high-quality seeds are kept - free from insects and impurities.
Fire - some like it hot
Some banksias need the heat of a bushfire to release the seeds from their woody cones. Here in the laboratory, the heat of a blowtorch is used to open the seed-bearing fruit walls, releasing the banksia seed for collection.
Water - smash and grab
The seeds of many rainforest plants are inside a fleshy fruit which is softened by soaking, so the seeds are more easily released. The seeds are then sieved and dried thoroughly before being packaged for long-term storage.
Air - unnatural selection
Native daisies produce a large number of single-seeded fruits on each flower head but many seeds are infertile. A mechanical aspirator is used to select the fertile seeds containing embryos, which are larger and heavier than infertile ones.
Burning a banksia cone releases the seeds.
Macerating the fruit removes the flesh and releases the seeds.
The zig-zag aspirator lifts seeds up on a column of air. Heavier seeds fall to the bottom, while infertile seeds and other debris are discarded.
The seed vault behind this room is one of the most biodiverse places on the planet. It holds seed collections of many of the 25,000 plant species that occur in Australia. Most of the seeds are from New South Wales species, and some are rare and threatened in the wild. By 2020 all New South Wales species will be represented either here or as living plants growing within the Australian Botanic Garden. The vault has the capacity to store this number of species many times over. It can also house large seed collections for use in the restoration of degraded habitats.
The success of conserving seeds for the long-term depends on the collection of good quality seed, correct preparation of the seed for storage and maintaining the collections in dry, cold conditions. The colder the storage temperature, the longer the seeds will last.
Dried to perfection
Seeds containing too much moisture will not survive the freezing process so they are prepared for storage by drying them at low humidity in the room next to the vault. The dried seeds are packed in strong aluminium bags to protect them from air and insects. Once packed and labelled, they are ready for storage at -20°C in the vault's freezer.
Seeds of many wattle (Acacia) species are expected to last hundreds of years in storage. Other species, such as waratahs (Telopea speciosissima), may have a much shorter lifespan in storage - perhaps only 40 years. These shorter-lived seeds will need to be re-collected frequently. Some plant species, including rainforest plants with fleshy fruits, have seeds that cannot be dried and frozen for storage.
Global seed conservation
Conserving plant species is a shared responsibility. Seedbanks around the world protect their collections by sending duplicate collections to other seedbanks. This spreads the risks associated with losing collections through disasters such as fire, theft or war. Duplicates of many of the Australian PlantBank seed collections are held at the Millennium Seed Bank in the United Kingdom.
Seeds are dried for storage in the vault (Image: Richard Weinstein).
Seeds of many species can remain viable for decades or even centuries in the freezer vault (Image: ©Richard Weinstein).
Tissue culture and beyond
Some plants produce seeds that are not suitable for seed-banking; other plants do not produce seed at all. An alternative way to conserve these species is to culture and bank their tissues.
Tissue culture involves taking very small pieces of plant (buds, shoot tips, or other parts) and growing them on special nutrient media in sterile conditions. This method allows the production of many plants from a single shoot - a great advantage when plants are rare. Many house and garden plants available in nurseries are grown by tissue culture.
Tissue culture can be used to produce identical copies (clones) of a plant that has desirable features. For many years, flannel flowers (Actinotus helianthi) were harvested from the wild for the cut-flower trade, sometimes unsustainably. Scientists here have developed a number of flannel flowers suited to cultivation. Using tissue culture techniques, these plants are grown by the thousands and made available for sale to gardeners around Australia.
Orchid seeds cannot germinate unless they are associated with a particular kind of fungus. The fungus grows into the seed and provides the nutrients that allow the embryo to germinate and grow. Tissue culture is used to mimic this natural process in the laboratory. The seeds and fungus are cultured together, resulting in the propagation of healthy orchid plants.
Cryo-storage involves immersing plant tissues and seeds in vats of liquid nitrogen at temperatures as low as -196°C. Under these conditions, plant tissue ages very slowly and can be kept in storage almost indefinitely. Cryo-storage of plant tissue is an alternative for preserving rainforest species, many of which have seeds that cannot be conserved by drying and freezing in the vault.
Tissue culture techniques can be used for conservation of very rare species, horticultural production and biological research.
A fungal mass (peloton) inside an orchid plant. The symbiotic association between orchid and fungus helps both species to complete their life cycle (Image courtesy Jiri Machac and Martin Vohnik, Institute of Botany, Academy of Sciences of the Czech Republic).
Scientists at the Australian PlantBank are investigating techniques for successful cryo-storage of Australian plant species.