Cross-kingdom virus infection: mycoviruses pave the way for spread into multiple fungal hosts

Abstract

My name is Liying Sun, and I am currently a professor at Northwest A&F University in China, as well as a cross-appointed professor at Okayama University in Japan. My research focuses on studying virus-host interactions and virus-vector interactions. Recently, we made a significant discovery of a novel negative-strand RNA virus that naturally infects both plants and fungi.

Diverse mycoviruses, or fungal viruses, infect and replicate within fungal hosts. Some of these fungal viruses can reduce the pathogenicity of their hosts, positioning them as potential biological control agents for fungal crop diseases. Unlike other eukaryotic viruses, mycoviruses are generally thought to lack extracellular routes of transmission. Instead, they disseminate naturally through vertical transmission via spores or horizontal transmission via hyphal anastomosis. However, the transmission of viruses through anastomosis between fungal strains is often restricted by vegetative incompatibility. During the colonization of plants by fungi, bidirectional exchanges of various molecules—including water, nutrients, proteins, and RNAs—occur between these two organisms. Recently, we discovered a natural transmission route for a negative-strand RNA virus from a plant to a fungus. This finding highlights the virus’s remarkable ability to adapt and spread among diverse hosts, providing a new perspective on virus evolution and challenging traditional views of plant and fungal viruses. Notably, this virus appears to decrease the pathogenicity of the fungal host while remaining asymptomatic in the plant host. This characteristic suggests its potential as a biocontrol agent against fungal diseases, offering a novel strategy for managing plant fungal infections. Furthermore, I will discuss the mechanisms of mycovirus extracellular transfer that facilitate cross-kingdom viral infection.