Cane toad genome sequenced for the first time

A group of scientists from the University of Sydney, UNSW, Deakin University and researchers from Portugal and Brazil have for the first time unlocked the DNA of the cane toad.

Co-author and winner of the 2016 Prime Minister’s Prize for Science Emeritus Professor Rick Shine said there had been major gaps in our understanding of cane toad genetics up until now.

A decade ago, researchers in Western Australia tried to sequence the cane toad genome but they encountered obstacles when it came to assembling it and did not complete the project.

The findings of the new research are published today in the journal GigaScience.

Professor Shine said having a draft cane toad genome would help to close important knowledge gaps and accelerate cane toad research. More toads can now be sequenced at a fraction of the cost and, with the genome freely available, anyone can now access it and conduct further research.

“Future analysis of the genome will provide insights into cane toad evolution and enrich our understanding of their interplay with the ecosystem at large – it will help us understand how the toad spreads, how its toxin works, and provide new avenues to try to control its population,” Professor Shine said.

“Very few amphibian genomes have been sequenced to date, so this is also great news for amphibians. Having a reference genome could provide valuable insights into how invasive species evolve to adapt to new environments.”

For this project, the Australian team worked at the Ramaciotti Centre for Genomics. UNSW senior lecturer Dr Rich Edwards, lead author of the study, said: “Sequencing and assembling a genome is a complicated process. By using the cutting-edge sequencing technology and expertise available at UNSW, we sequenced 360-odd billion base pairs and assembled one of the best quality amphibian genomes to date.”

Project leader and Professor in Microbiology and Molecular Biology at UNSW, Peter White, said having the genome would also help researchers to find new options for controlling the toad population.

Cane toads are a poisonous amphibian that is a threat to many native Australian species. They are highly adaptable and have destructive impacts on native fauna in invaded regions, of which there are many; they are present in 138 countries. Since the toad was introduced in Queensland in 1935, it has spread widely and millions of toads now occupy more than 1.2 million square kilometres.

These findings will assist researchers in control methods – such as Conditioned Taste Aversion (CTA) – being led out of the University of Sydney’s Shine Lab.

Professor Shine last year received an Australian Research Council Linkage Grant to roll out his CTA method of feeding small amounts of ‘cane toad sausages’ to native animals ahead of the cane toad front as it hops southward. The result is the Cane Toad Coalition – a one-stop-shop as part of a united front trialling the largest cane-toad mitigation strategy to date.

The cracking of the cane toad genome will help piece together information about the toad’s strengths and vulnerabilities, assisting concerted efforts to overcome this feral predator.