QUEENSLAND University scientists have published research results about a cure for myrtle rust
There’s a cure for myrtle rust, the wind-borne plant fungus that threatens New Zealand natives like pōhutukawa, mānuka, rātā, kānuka, swamp maire and ramarama, as well as commercially-grown species such as eucalyptus and fiejoas.
The cure involves the use of double strand RNA developed at the University of Queensland with collaboration from PhD students at the University of Canterbury.
The treatment can both prevent and cure infection caused by myrtle rust which is devastating native Australian plants.
“We found that when the double stranded RNA was applied to a healthy tree, it prevented the plant from being infected,” PhD candidate Rebecca Degnan said.
“What’s even more exciting, when we infected the plants and applied the double stranded RNA as late as two weeks post infection, the plants recovered.
“It’s significant because our previous studies didn’t have that curative aspect, so being able to apply a treatment after infection gives it more potential.”
Dr Grant Smith Principal Scientist & Science Team Leader, Pathogen Biosecure Environments at Plant and Food Research said the development was really exciting.
“Because basically right now we don’t have any way of stopping this pathogen,” he said.
“But it’s like a lot of things, it’s working in a laboratory. The issue is getting it out working in the field which is still a bit of a gap there.”
The treatment has been squirted on some eucalypts in a Brisbane glasshouse, but proper field trials have yet to happen.
“There is still a lot of work to do in particular when operating out on the landscape, a lot of things to consider before we would start doing that,” Grant said.
“I have been collaborating and interacting with the Australians for some length of time, the guys in Brisbane. And we have slowly been making our way through to try and get the basic understanding of how this pathogen operates. It’s fairly unique in a lot of ways.
“So we still need to try and make absolutely certain. Some of that work’s been done already in Brisbane around specificity and it’s showing the technology will work on more than one rust fungi, which is exciting.
“But we have still got to make sure that we can deliver it properly, and make it work the way we want it to work.”
Grant’s focus has been on leading and contributing to research in response to the incursion of the myrtle rust pathogen since 2017.
This includes understanding pathogen resistance in taonga myrtaceae species, contributing to the sequencing and assembly of the pathogen genome, and investigating the molecular mechanisms of pathogenicity and the development of targeted control options including double strand RNA/ RNAi technology.
It is a technology that can be used in New Zealand as it is not genetic engineering technology, he said. There is no change to the DNA of the organism.
“Before the RNA is turned into a protein or something it is destroyed, so it doesn’t touch the genes at all,” he said. “It isn’t genetic engineering technology.
“There are human medicines treatments for human diseases that are double stranded RNA based.”
Double strand RNA was also a natural product, he said.
“Our regulatory system is different from Australia, but (dsRNA) is basically recognised as a technology. Provided you have done the work, got the right permits, it could be deployed on the landscape.
“It’s working in the lab. We know it’s taken a lot of time to get there.
“We’ve been feeding them data targets, which RNA molecules to go after, we suggested might be able to control it with completely different set of RNA. We have experimental proof that works as well.
“We know that most myrtaceous plants we have in New Zealand are susceptible to an infection.There is some resistance mainly in manuka and kanuka, but resistance is not widespread and we also know that it’s a complicated resistance because it’s based on specificity in those plants. It’s a complex beast”
Myrtle rust was detected in Australia in 2010. It has since spread all the way up the east coast and into the Northern Territory, as well as Western Australia.
There are more than 2,000 species of Myrtaceae native to Australia, with 16 species of rainforest trees on the east coast facing extinction.
The Queensland University team would now test the RNA treatment in field trials.
It’s light at the end of the tunnel, Grant said. They just didn’t know yet how long the tunnel was.
