Genomic technique identifies origin of plant material

Scientists at the Royal Botanic Garden, Sydney, have adapted innovative genomic techniques that allow the accurate identification of the exact origin of plant material.

The garden’s Manager Evolutionary Ecology Dr Maurizio Rossetto said the discovery happened when he applied whole-genome barcoding techniques in an effort to determine the origins of an ancient Australian red cedar (Toona ciliata) growing in the Royal Botanic Garden.

“Records suggested the tree originated in the Parramatta region, where it is now extinct, and seedlings were brought to the garden in 1822 by Charles Fraser, the garden’s first superintendent,” Dr Rossetto said.

The garden’s staff were keen to use the cedar’s cuttings to begin a restoration program in the Parramatta area, according to Dr Rossetto, but “decided to double check with the Evolutionary Ecology team to be certain they were doing the right thing”.

“Using this technology, we unravelled the mystery and found that the second-oldest tree in the Royal Botanic Garden was actually from the Dorrigo region in northern NSW,” he said.

“The DNA-based findings suggest that the tree originated from a forestry trial using seed material sourced in Dorrigo and it was not native to the Parramatta region at all.

“Now that we’ve determined that the Australian red cedar was an introduced species in the Parramatta region, the cuttings from our ancient gem of the garden will not be planted there, but rather at all three Botanic Gardens managed by the Trust.”

Dr Rossetto said the method will now be replicated across over 80 rainforest tree species to investigate species dynamics, guide provenance sourcing for ecological restoration projects and provide background genetic barcodes for similar forensic studies.

“The general consensus is that you use genetically adapted material rather than introduced trees and plants for ecological restoration, because introduced species have the potential to pollute local diversity,” he explained.

“These new findings show how important it is to determine the provenance of material before restoration begins.”