Rare plants live on through tissue culture
By Praful Umaretiya
Western Australia’s unique flora faces increasing threats from habitat loss and environmental changes. Tissue culture techniques have emerged as a vital tool for horticulturists and conservationists in propagating rare and vulnerable species, which can be rapidly produced from a limited number of initial specimens.
Among the species Kings Park is currently working with, most present significant challenges in traditional propagation methods due to their seed dormancy and rooting difficulties. But by advancing our techniques in seed germination, initiation, and propagation through tissue culture, we are ensuring that some of these species not only survive but thrive in their natural habitats, positively impacting Western Australia’s biodiversity.
Conservation impact of tissue culture
The application of tissue culture in the conservation of rare Australian plants offers several key benefits:
- Preservation of genetic diversity: Tissue culture enables the preservation of genetic material from rare species, ensuring that genetic diversity is maintained. This is crucial for species like Synaphea spinulosa and Calectasia narragara, which may be limited in number in their natural habitats.
- Restoration of populations: By producing large numbers of healthy plants in a short period, tissue culture facilitates the restoration of populations in their native environments. For example, the successful germination and propagation of vulnerable species such as Tricoryne elatior can significantly boost their populations.
- Research and education: Tissue culture techniques provide a platform for research into plant physiology and genetics, contributing to a better understanding of these rare species, and engaging the public through educational programs about the importance of plant conservation can foster greater community involvement.
- Mitigation of threats: As environmental pressures increase, the ability to cultivate rare species in vitro can help mitigate the risks of extinction. Tissue culture acts as a safeguard against threats such as climate change, invasive species, and habitat destruction.
Species under investigation
The Kings Park team has initiated the following Western Australian species into tissue culture either by seed germination and/or micropropagation:
- Patersonia spirifolia: This striking plant, known for its spiral leaves, belongs to the iris family (Iridaceae). Its seeds are notoriously slow to germinate, making traditional propagation challenging. The Kings Park team have successfully initiated tissue culture plants using side shoots obtained from a potted specimen.
- Geleznowia exima: A rare species belonging to the Rutaceae family, this plant faces challenges in establishing seedlings in nursery conditions due to its difficulty germinating and rooting from cuttings. Tissue culture significantly enhances propagation efforts, allowing for successful initiation from fresh shoots of potted plants.
- Geleznowia amabilis: This species has demonstrated considerable potential in tissue culture propagation, having been successfully initiated and deflasked by the Kings Park team. It has also benefited from the rapid multiplication capabilities of tissue culture, enabling researchers to produce a larger number of viable plants more quickly.
- Tetratheca butcheriana: With its limited natural populations, the survival of this species hinges on effective conservation strategies. Rapid propagation through tissue culture is essential for maintaining genetic diversity and ensuring the species can thrive in the wild. This method allows for the establishment of new plants that can support existing populations and potentially lead to re-establishment in areas where it has declined.
- Scaevola macrophylla: This species has also been successfully initiated and deflasked through tissue culture, underscoring the method’s effectiveness in producing healthy plants. By generating viable specimens, tissue culture not only boosts numbers but also aids in the restoration of this species within its natural ecosystem.
- Calectasia narragara: This species is particularly challenging to propagate due to its difficult rooting characteristics. To address this, the Kings Park team is trialling various treatments in tissue culture to improve rooting success and overall plant health. By experimenting with different growth media and hormonal treatments, we aim to identify optimal conditions that promote robust root development, and conserve this species’ genetic diversity.
- Tricoryne elatior: Tissue culture facilitates the production of healthy plants from difficult-to-germinate seeds of this species. After seeds were successfully germinated from tissue culture, we now have plants of this species growing in the Kings Park nursery.
- Synaphea spinulosa and Synaphea quartzitica: Both species are important to the local ecosystem, with tissue culture techniques aiding in their propagation.
Tissue culture methods in species propagation
Tissue culture allows for the rapid multiplication of plants, ensuring genetic uniformity and health, which is particularly important for rare species. Each species has specific requirements for success:
- Initiation: For species like Patersonia spirifolia and Geleznowia exima, the Kings Park team have found the initiation phase to be critical, as the seeds of these species often exhibit low germination rates in conventional settings.
- Germination and multiplication: This is especially effective for difficult-to-root species, allowing for the generation of a larger number of plantlets from a single explant. For species with difficult germination, such as Patersonia spirifolia, the Kings Park team are trialling specific hormone ratios to enhance the likelihood of successful seedling development.
- Rooting: This phase is challenging for some species, such as Calectasia narragara, which may struggle to transition from the culture medium to soil. Here, careful manipulation of the hormone balance is essential to encourage successful rooting.
- Deflasking and acclimatization: This step is essential to ensure the plants can survive in their natural habitats. The Kings Park team have successfully deflasked several species including Geleznowia amabilis and Scaevola macrophylla, marking a significant milestone in their propagation journey.
Challenges and future directions
Despite its advantages, tissue culture is not without challenges. The high cost of setting up and maintaining sterile environments, the need for skilled personnel, and the potential for somaclonal variation (genetic changes that can occur during tissue culture) are factors that must be considered.
Future research should focus on refining protocols specific to each species to enhance rooting success and overall plant health. Kings Park is actively collaborating with local universities, conservation organisations, and local nurseries to strengthen these efforts. These partnerships not only enhance our technical capabilities but also foster knowledge exchange centred on rare Australian plants, ultimately benefiting WA’s biodiversity.
The future of our rare plant species depends on our ability to innovate and adapt, making tissue culture an essential component of conservation efforts.
Praful Umaretiya
Plant Breeder
Kings Park and Botanic Garden
praful.umaretiya@dbca.wa.gov.au