Waratah genome mapped for the first time

In a world-first, researchers have mapped the genome of the striking crimson flower, Telopea speciosissima – the most commonly known species of waratah.

This iconic flower has cultural, commercial and ecological significance – it’s best known as the New South Wales waratah, and is our most populous state’s floral emblem – but before now, no one had put together its reference genome.

This means that scientists hadn’t yet mapped its complete set of genetic instructions, containing all the information to build the organism. Essentially, genome mapping is used to identify and record where different genes are and the distances between them on a chromosome. Just like a train map shows different stops to help you navigate a city, a genome map helps scientists to navigate around a genome.

Usually, genetic studies focus on species of agricultural importance (although recently scientists mapped the genome of an extinct but resurrected plant).

But lead researcher of the new study, Stephanie Chen, says that mapping genomes not only gives us a better understanding of the natural world, but also helps conservation efforts.

“Understanding the genetic make-up of the waratah will give us better insight into its evolution and environmental adaption, ultimately helping us better conserve it, as well as inform breeding efforts,” explains Chen, who is a PhD candidate at the Australian Institute of Botanical Science and UNSW Sydney.

But putting together the waratah genome wasn’t an easy task. First, the team had to take leaf samples of a ‘reference individual’; they chose a plant on land belonging to the Blue Mountains Botanic Garden at Mount Tomah, west of Sydney.

But they took the initial sample before the Black Summer fires of 2019–20 – and they hadn’t counted on the plant burning.

“That was a bit of a spanner in the works, but we waited for it to resprout and lucky it did,” Chen says. “Waratahs can regenerate from their lignotuber and fire is important in their lifecycle.”

They took the extra samples needed, then set about mapping the genome.

Chen says that it was sort of like putting together a puzzle – but in hard mode, because the team couldn’t see the picture on the box.

“Imagine you’re putting together a puzzle and it has billions and billions of pieces,” she says. “With the help of three different sequencing technologies, we’ve been able to link all the pieces that are the bits of DNA together, ultimately revealing the puzzle.”

Co-author Richard Edwards, an expert in genomics and bioinformatics at UNSW, says that this new research will allow scientists to understand evolution at a whole other level.

“Complex organisms, like plants and animals, package up their DNA in multiple chromosomes,” he explains. “Not only have we sequenced the genome, we’ve been able to reconstruct the bulk of the waratah’s eleven chromosomes.

“This is a bit like solving eleven jigsaws simultaneously, when all the pieces could belong to any picture.”

Another co-author, evolutionary and computational biologist Jason Bragg, says that mapping the waratah genome will also help us manage other Australian flora.

“We use genetics to study the populations of many species,” he says. “It helps us understand how to conserve plant species that are endangered and how to restore populations of plants that are widespread.

“When we have a reference genome it’s our opportunity to try and see further and learn new things. Hopefully developing this amazing resource for this one awesome species gives us the opportunity to inform the decisions we make for other species, because it becomes a model.”

The research is published in the journal Molecular Ecology Resources.