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The search for genetic variation

Genetic diversity in the Wollemi Pine is extremely low. Previous research found no genetic variation in the Wollemi Pine despite extensive tests (Peakall et al. 2003). Such low genetic diversity could mean that the species is less adaptable to threats such as climate change, illegal harvesting, fire and pathogens such as Phytophthora. “However, these earlier studies were performed prior to the widespread use of genome sequencing, and their conclusions were based on a limited fraction of the Wollemi Pine genome” (Yap et al. 2015).

Over time, horticultural researchers have observed variations between cuttings taken from different parent trees. "Although we didn't initially find any genetic variation, we knew that with changing technology we would eventually detect differences between the trees," said Dr Cathy Offord. 

Using new technology in partnership with collaborators at the Ramaciotti Centre at UNSW, the entire chloroplast genome was recently sequenced (Yap et al. 2015). This study showed that within the family Araucariaceae, the Wollemi Pine chloroplast is most closely similar to Agathis species. 

Using the new chloroplast genome as a reference, Greenfield et al. (2016) used novel DNA sequencing approaches to explore whole chloroplast variation among individual trees from the four known Wollemi Pine sites. Their study revealed three different chlorotypes of Wollemi Pine across the sites, a result which will inform future plans to conserve this critically endangered species.

This knowledge improves our understanding of the species biology, evolution and horticultural potential. "Knowing that we have different genetic individuals will allow us to select the right mix when we save seeds, propagate plants and prepare new wild sites," said former NSW Environment Minister Mark Speakman.

Papers

  • *Greenfield A, *McPherson H, Auld T, Delaney S, *Offord C A, *Van Der Merwe M, *Yap J-Y S, *Rossetto M, 2016. Whole-chloroplast analysis as an approach for fine-tuning the preservation of a highly charismatic but critically endangered species, Wollemia nobilis (Araucariaceae). Australian Journal of Botany 64(8): 654-658. 
  • Peakall R, Ebert D, Scott L J, *Meagher P F, and *Offord C A, 2003.  'Comparative genetic study confirms exceptionally low genetic variation in the ancient and endangered relictual conifer, Wollemia nobilis (Araucariaceae)'.  Molecular Ecology, 12(9):2331-2343.  
  • *Yap J-Y S, Rohner T, *Greenfield A, *Van Der Merwe M, *McPherson H, Glenn W, Kornfeld G, Marendy E, Pan A Y H, Wilton A, Wilkins M R, *Rossetto M and Delaney S K, 2015. 'Complete Chloroplast Genome of the Wollemi Pine (Wollemia nobilis): Structure and Evolution' PLOS ! One 10(6): e0128126. doi:10.1371/journal.pone.0128126

* indicates staff and students of the Royal Botanic Gardens Sydney

See also

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