As harmful as viruses may sound, they can help farmers when it comes to dealing with plant pathogens.
Scientists at Osaka Metropolitan University have discovered that a mycovirus infects plant-pathogenic oomycete Globisporangium ultimum can increase the sensitivity of the latter to specific fungicides. Their findings could lead to innovative approaches to controlling plant diseases, reducing reliance on chemical treatments and minimizing agricultural losses.
Their results have been published in Microbiological research on May 3.
Mycoviruses, or fungal viruses, infect both fungi and fungus-like organisms such as oomycetes. Oomycetes, commonly known as water molds, include some of the most devastating plant pathogens and pose a serious threat to global food security. However, when these oomycetes are infected by certain mycoviruses, their ability to cause disease can be weakened – a phenomenon known as hypovirulence – making mycoviruses potential biological control agents.
Mycoviral infections are multifaceted; they can reduce or increase virulence or remain hidden without obvious symptoms. Despite the growing number of recently identified mycoviruses, their effects on host oomycetes have remained largely unexplored.
“Since mycoviruses can have a significant impact on the ecology of oomycetes, we felt it was crucial to study their effects at both the phenotypic and gene expression levels,” said Tomofumi Mochizuki, associate professor at Osaka Metropolitan University’s Graduate School of Agriculture and corresponding author of this study.
The research team focused on it Globisporangium ultimum, an important soil-occurring oomycete responsible for weakening and root rot in many plant species. They first created a virus-free isogenic strain of G. ultimate by high-temperature culture and then compared its characteristics and gene expression with the virus-infected isogenic strain.
The results show that the virus-infected isogenic strain was more sensitive to metalaxyl, one of the four fungicides tested, compared to the virus-free isogenic strain. No significant differences in growth rate and structure were observed between these isogenic strains in the absence of metalaxyl. Using a high-throughput screening technique called RNA-seq to analyze the gene expression profile, the researchers found that the virus-infected isogenic strain had lower expression of certain genes known as ABC-type transporters, which are known is that they contribute to fungicide resistance.
“Our results indicate that mycoviral infections alter the sensitivity of the host oomycete to fungicides,” said Aika Higuchi, a master’s student and the first author of this study.
These findings advance current understanding of the role mycoviruses play and their potential for sustainable agriculture. The team plans to further explore the promise of mycoviruses as a biological control tool across different species and environmental conditions.
“Our research shows that the effects of viral infection on host oomycetes can only be observed under certain conditions,” Mochizuki said. “Even if it seems that a viral infection has no effect at first glance, it is necessary to analyze it from different perspectives.”
