Myrtle rust, an invasive fungal disease, has wreaked havoc on certain plant species in Australia over the past decade. This disease primarily affects plants in the Myrtaceae family, which make up 10% of Australian plant biodiversity and include eucalypts, paperbarks, and lilly pillies. The impact of myrtle rust has been devastating, leading to the destruction of trees and their canopies, the extinction of species in certain areas, and economic losses for industries that rely on tree cultivation.
Traditional approaches to managing tree diseases have proven ineffective against myrtle rust. Applying fungicides to kill all fungi or breeding plants for resistance are not viable options due to the vast number of species affected and their remote locations. Some species, such as Lenwebbia sp. Main Range, which grows exclusively on cliff faces in the Nightcap Range in northern New South Wales, are on the brink of extinction.
To address this issue, researchers have developed a highly targeted treatment for myrtle rust using RNA technology similar to that used in COVID vaccines. This treatment involves a spray that can restore even severely infected trees to health within approximately six weeks.
The treatment utilizes a molecular mechanism called “RNA interference,” which is present in most plants, animals, and fungi. RNA interference is a natural defense mechanism triggered by cells when they detect double-stranded RNA, typically associated with viruses or other threats. By designing double-stranded RNA that matches essential genes in the myrtle rust fungus and spraying it on infected plants, researchers can activate the fungus’s RNA interference mechanism, disrupting its survival.
The treatment has shown promising results in inhibiting the progress of myrtle rust and even curing severely infected plants. Additionally, double-stranded RNA can be used as a preventive measure by spraying it onto plants to prevent spore germination and disease development.
To ensure the treatment only affects the myrtle rust fungus, researchers designed it using “barcoding genes” that uniquely identify the species. Barcoding genes are ideal targets for RNA interference as they are identical within a species, differ between closely related species, and control essential cellular functions. The treatment’s impact is long-lasting, and the risk of the pathogen developing resistance is minimized.
While the RNA treatment offers a targeted solution for managing myrtle rust, an integrated approach is still necessary. The Australian government’s myrtle rust action plan recommends combining various strategies to control this destructive disease. In the future, incorporating double-stranded RNA into management efforts can help combat the myrtle rust epidemic in Australia, benefiting conservation, industry, and the preservation of culturally significant trees.