Molecular characterization and biocontrol potential of Trichoderma spp. against Fusarium oxysporum f. sp. dianthi in carnation

Abstract

Background: Carnation, a major cut flower product cultivated economically in Iran, faces economic challenges due to the devastating Fusarium wilt caused by Fusarium oxysporum f. sp. dianthi (Fod). To address this issue, twenty-five Trichoderma harzianum and T. viride isolates were collected from the rhizosphere soil of three Iranian provinces: Tehran, Markazi, and Fars. RAPD-PCR was applied to analyze the genetic relatedness of the isolates. Results: The RAPD profiles showed genetic diversity among the isolates, with two major clusters. The antagonistic potential of the twenty isolates was evaluated against the carnation wilt caused by Fod. The results showed that Th1, Th7, and Th2 isolates of T. harzianum significantly inhibited Fod mycelial growth (58, 56.5, and 48.6%, respectively). Among T. viride isolates, Tv5, Tv4, and Tv7 exhibited the highest antifungal ability to inhibit mycelial growth. All investigated isolates of Trichoderma secreted volatile compounds that hindered Fod mycelial growth, with isolates of T. harzianum ranging from 9.3 to 67.5% inhibition and those of T. viride from 25.2 to 50.2%. Additionally, the experiment on competitive saprophytic ability indicated that maximum colonization occurred with Th1, Th7, and Th2 isolates at 78.2, 70.8, and 69.8%, respectively. Lastly, the greenhouse experiment showed a complete pathogen eradication or significant inhibition in the infected carnation after T. harzianum and T. viride. Conversely, control treatment with the Fod pathogen died after 90 days. Conclusions: The investigation suggested that Trichoderma spp. could be a potential biocontrol agent to mitigate Fusarium wilt in carnation and improve production quality, replacing chemical pesticides.