In the vast orchards of the Xinjiang Uygur autonomous region, a silent battle rages between walnut trees and a persistent foe: walnut canker, a disease that has long plagued farmers and threatened the region’s lucrative walnut industry. The culprit behind this scourge is a fungus known as Cytospora chrysosperma, which has proven notoriously difficult to control. However, a glimmer of hope has emerged from the labs of Shihezi University, where researchers have identified a potential game-changer in the fight against this destructive disease.
Led by Yingjie Mi, a scientist at the Key Laboratory of Oasis Agricultural Pest Management and Plant Protection Resources Utilization, the research team has turned its attention to an unusual ally: mycoviruses. These are viruses that infect fungi, and some have been shown to reduce the virulence of their fungal hosts. “Mycoviruses offer a promising avenue for biological control,” Mi explains. “By infecting the fungus that causes walnut canker, these viruses could potentially turn a harmful pathogen into a benign or even beneficial organism.”
The study, published in the journal Viruses, involved analyzing 31 strains of C. chrysosperma using metatranscriptomic sequencing. The researchers identified seven new mycoviruses, including Botrytis cinerea partitivirus 5 (BcPV5), Gammapartitivirus sp-XJ1 (GVsp-XJ1), Botoulivirus sp-XJ2 (BVsp-XJ2), Luoyang Fusar tick virus 2 (LfTV2), Leptosphaeria biglobosa narnavirus 17 (LbNV17), Sclerotinia sclerotiorum narnavirus 6 (SsNV6), and Cytospora ribis mitovirus (CrMV3). Among these, BcPV5, GVsp-XJ1, BVsp-XJ2, CrMV3, and LfTV2 were found to co-infect a strain of C. chrysosperma known as WS-11, significantly reducing both its colony growth rate and virulence.
The implications of this discovery are profound. If these mycoviruses can be harnessed and deployed effectively, they could provide a sustainable and environmentally friendly solution to walnut canker. “The potential for mycoviruses to control plant diseases is immense,” Mi notes. “Not only do they offer a natural alternative to chemical fungicides, but they also have the potential to enhance the overall health of the ecosystem.”
The research also sheds light on the mechanisms by which mycoviruses interact with their fungal hosts. For instance, some mycoviruses can reprogram fungal metabolism, leading to the production of antifungal compounds that inhibit competing pathogens. Others can alter the host’s gene expression and metabolic pathways, reducing virulence and even transforming pathogenic fungi into beneficial endophytes.
As the world grapples with the challenges of sustainable agriculture and climate change, the search for innovative and eco-friendly solutions has never been more urgent. The discovery of these mycoviruses in C. chrysosperma represents a significant step forward in the quest for effective and sustainable biocontrol methods. “This research opens up new possibilities for managing walnut canker and other fungal diseases,” Mi concludes. “By understanding and leveraging the power of mycoviruses, we can develop more resilient and productive agricultural systems.”
The findings published in Viruses (translated to English) offer a tantalizing glimpse into a future where mycoviruses play a central role in disease management. As researchers continue to unravel the complexities of these fascinating viruses, the potential for transformative change in the agricultural sector becomes increasingly clear. The battle against walnut canker may be far from over, but with the discovery of these mycoviruses, farmers and scientists alike have a new weapon in their arsenal—a weapon that could revolutionize the way we approach plant disease control.