Isolation and Characterization of <i>Pseudomonas</i> sp. HX1, <i>Streptomyces luteogriseus</i> HR40, and <i>Streptomyces flavofungini</i> HR77 as Promising Biocontrol Agents Against Verticillium Wilt in Hops Affected by <i>Verticillium nonalfalfae</i>

<i>Verticillium</i> spp. are soil-borne fungal pathogens capable of infecting over 400 plant species via their root systems, with each species demonstrating a distinct host range. The primary host of <i>Verticillium nonalfalfae</i> is the hop plant (<i>Humulus lupulus&l...

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Bibliographic Details
Main Authors: Seyedehtannaz Ghoreshizadeh, Carla Calvo-Peña, Marina Ruiz-Muñoz, Maja Dobrajc, Sebastjan Radišek, Juan José R. Coque, Rebeca Cobos
Format: Article
Language:English
Published: MDPI AG 2025-04-01
Series:Horticulturae
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Online Access:https://www.mdpi.com/2311-7524/11/5/459
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Summary:<i>Verticillium</i> spp. are soil-borne fungal pathogens capable of infecting over 400 plant species via their root systems, with each species demonstrating a distinct host range. The primary host of <i>Verticillium nonalfalfae</i> is the hop plant (<i>Humulus lupulus</i>), which becomes affected by Verticillium wilt and, in severe cases, dieback. A dual screening approach was employed to isolate Streptomycetes as potential biocontrol agents from the hop root systems alongside other bacterial species from hop xylem. Three <i>Pseudomonas</i> strains from the xylem and three <i>Streptomyces</i> strains from the roots were selected based on their in vitro antifungal activity against <i>Verticillium dahliae</i> and/or <i>V. nonalfalfae</i>. Their potential for controlling Verticillium wilt was further assessed through in planta assays conducted under greenhouse conditions. The results demonstrated that <i>Pseudomonas</i> sp. HX1, <i>Streptomyces luteogriseus</i> HR40, and <i>Streptomyces flavofungini</i> HR77 significantly reduced the disease severity index by 32.56% compared to artificially infected control plants. In contrast, the commercial biocontrol product Serenade<sup>®</sup> ASO, containing <i>Bacillus amyloliquefaciens</i> QST 713, achieved a reduction of 13.96%. These findings underscore the potential of the selected bacterial strains as promising candidates for the biological control of Verticillium wilt in hops affected by <i>V. nonalfalfae</i>.
ISSN:2311-7524