The pandemic strain of the myrtle rust pathogen, Austropuccinia psidii, hosts multiple mycoviruses

Area of Science:

• Plant pathology
• Mycology
• Virology

Background:

• Myrtle rust, caused by Austropuccinia psidii, is a significant invasive pathogen threatening Myrtaceae family plants globally.
• Understanding Austropuccinia psidii's biology is crucial for developing effective disease management strategies.

Purpose of the Study:

• To investigate the presence of mycoviruses within the pandemic strain of Austropuccinia psidii.
• To assess the efficacy of the fungus' RNA interference (RNAi) pathways in managing mycoviral infections.

Main Methods:

• Extraction and sequencing of double-stranded RNA (dsRNA) from Austropuccinia psidii.
• Identification and characterization of mycoviruses present in the pathogen.
• Analysis of RNA interference pathway activity in relation to mycovirus presence.

Main Results:

• At least eight distinct mycoviruses were identified in the pandemic strain of Austropuccinia psidii.
• Identified mycoviruses include both double-stranded RNA (dsRNA) and positive-sense single-stranded RNA (ssRNA) viruses.
• The RNA interference pathways of Austropuccinia psidii were found to be active but incapable of suppressing the detected mycoviruses.

Conclusions:

• The pandemic strain of Austropuccinia psidii is infected with a diverse range of mycoviruses.
• The fungus's RNA interference mechanisms are insufficient to control these viral infections.
• Further research into mycovirus-host interactions may offer novel avenues for controlling myrtle rust disease.