A Breakthrough in Myrtle Rust Treatment 

Researchers at the University of Queensland (UQ) have made a significant breakthrough in the fight against myrtle rust, an invasive fungal disease that has been devastating native Australian plants in the myrtle family such eucalypts, bottlebrushes and paperbarks.

Rebecca Degnan, Dr Anne Sawyer and Prof. Neena Mitter worked with the to Department of Primary Industries to develop an environmentally friendly spray that uses RNA technology to both prevent and cure myrtle rust infection. The spray works by using double-stranded RNA (dsRNA) to target and block essential fungal genes. This uses the same underlying patented RNA technology as the whitefly pesticide we have previously reported and demonstrates the ability for rapid adaptation of this technology to new targets.

Rebecca Degnan, Dr Anne Sawyer and Prof. Neena Mitter worked with the Department of Primary Industries to develop an environmentally friendly spray that uses RNA technology to both prevent and cure myrtle rust infection. The spray works by using double-stranded RNA (dsRNA) to target and block essential fungal genes. This uses the same underlying patented RNA technology as the whitefly pesticide we have previously reported and demonstrates the ability for rapid adaptation of this technology to important new targets.

The dsRNA spray was effective in laboratory trials and when applied to healthy trees, it prevented infection. Remarkably, when applied to infected plants as late as two weeks post-infection, the plants recovered.

Scanning electron microscope images of untreated (left) and treated (right) myrtle rust spores on rose apple leaves.

Scanning electron microscopy at Microscopy Australia’s University of Queensland facility was used to visualise the myrtle rust infection on leaves and the effects of both preventative and curative dsRNA treatments.

Since myrtle rust was first detected in New South Wales in 2010, it has spread up the east coast and into the Northern Territory, Western Australia and New Zealand. The researchers will now test the RNA treatment for effectiveness in field trials to see if it works in a real-world setting. They will also test the spray’s longevity and whether the initial dose can protect new growth that emerges after spraying.

R. Degnan et al., Communications Biology 2023
DOI: 10.1038/s42003-023-05618-z