Verticillium albo-atrum partitivirus 1 Is a highly prevalent and stably maintained cryptic virus of hop-associated Verticillium nonalfalfae

Miljanić, Vanja (author), Jakše, Jernej (author), Radišek, Sebastjan (author), Stajič, Ester (author), Štajner, Nataša (author)

The soilborne plant-pathogenic fungus Verticillium nonalfalfae causes Verticillium wilt in hop. Infections caused by its highly virulent (lethal) pathotype can lead to the development of a severe level of disease that poses a major threat to hop production. In this study, we investigated the occurrence of mycoviruses in V. nonalfalfae isolates representing different geographical regions and virulence groups using double-stranded RNA isolation and high-throughput sequencing. Notably, Verticillium albo-atrum partitivirus 1 (VaaPV1) was detected in 46 of 90 isolates (51.1%), including both lethal and mild pathotypes. Thirty isolates were sequenced, revealing low genetic divergence, with nucleotide identities of 93.9%–100% for RdRp and 94.5%–100% for CP. The low dN/dS ratio of the RdRp gene (0.119) further indicated strong purifying selection. VaaPV1 was efficiently maintained during fungal growth: hyphal tipping failed to eliminate the virus from any of 70 regenerated cultures, while only 13 of 73 cultures regenerated from protoplasts were virus-free. Furthermore, VaaPV1 was transmitted horizontally through hyphal anastomosis from all tested donor isolates. Comparisons between infected and isogenic virus-free isolates revealed no significant differences in fungal growth or virulence on hop, indicating that VaaPV1 establishes a cryptic infection without detectable phenotypic effects under the conditions tested. Overall, our findings demonstrate that VaaPV1 is highly prevalent, genetically conserved and stably maintained in hop-associated V. nonalfalfae, providing a baseline for future studies of the ecological and biological significance of mycovirus infections in this vascular wilt pathogen.

• Language: English
• Keywords: hop, mycovirus, VaaPV1, Verticillium wilt
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: BF - Biotechnical Faculty
• Publication status: Published
• Publication version: Version of Record
• Year: 2026
• Number of pages: 12 str.
• Numbering: Vol. 75, Iss. 5, art. e70298
• PID: 20.500.12556/RUL-190604
• UDC: 578
• ISSN on article: 0032-0862
• URN: https://bsppjournals.onlinelibrary.wiley.com/doi/10.1111/ppa.70298
• DOI: 10.1111/ppa.70298
• COBISS.SI-ID: 303217411
• Publication date in RUL: 30.10.2026

Record is a part of a journal

• Title: Plant Pathology
• Shortened title: Plant Pathol.
• Publisher: Her Majesty's Stationery Office
• ISSN: 0032-0862
• COBISS.SI-ID: 5661191

Licences

• License: CC BY 4.0, Creative Commons Attribution 4.0 International
• Link: http://creativecommons.org/licenses/by/4.0/
• Description: This is the standard Creative Commons license that gives others maximum freedom to do what they want with the work as long as they credit the author.

Secondary language

• Language: Slovenian
• Keywords: hmelj, mikovirusi, verticilijska uvelost

Projects

• Funder: ARIS - Slovenian Research and Innovation Agency
• Project number: Z4-50137
• Name: Mikovirusi uporabni za biološko zatiranje fitopatogene glive Verticillium nonalfalfae

• Funder: ARIS - Slovenian Research and Innovation Agency
• Project number: P4-0077
• Name: Kmetijske rastline - genetika in sodobne tehnologije