The interest in fungal viruses (mycoviruses) is increasing because of their potential contribution to sustainable agriculture as biological control agents of pathogenic fungi. Previous ly we identified and characterized FodV1, a chryso-like mycovirus which induces hypovirulence in Fusarium oxysporum f. sp. dianthi (Fod). FodV1 accumulates at unusually high levels in the host and was detected in total nucleic acid samples. To further identify viruses in Fod, in this work we applied cellulose column chromatography to analyze the incidence of mycoviral dsRNA molecules in a wide collection of isolates from different geographic origin (Colombia, Morocco, and Spain). A total of 300 isolates were analyzed by this technique, finding evidence of viral infection in 40 of them. These isolates exhibited five different dsRNA banding patterns characteristic of different viral families. A my covirus representative of each dsRNA banding pattern was selected for molecular characterization. Initial sequence data shows that a monopartite 2 kb mycovirus corresponds to a mitovirus and that a 4 dsRNA segment virus corresponds to a member of the newly proposed family Alternaviridae. Very interestingly, one of the dsRNA patterns identified corresponded to a single segment of approximately 9 kb, thus potentially corresponding to a member of the family Hypoviridae which has been clearly associated to hypovirulence. Two Fod isolates from Marocco exhibited this pattern. Partial sequen cing of this new mycovirus confirmed its similarity with other pre viously described hypoviruses. This is the first report of a member of the family Hypoviridae in the species F. oxysporum. In order to analyze its effect on the fungal host, we have transferred it from its naturally infected isolate to a hygR -tagged isolate by hyphal anastomosis. Phenotypic differences of the versions with and without virus of the recipient isolate will be investigated in order to determine the putative hypovirulent nature of this new hypovirus.

Trabajo presentado en el XVIII Congreso de la Sociedad Española de Fitopatología (SEF), celebrado en Palencia del 20 al 23 de septiembre de 2016.

Research supported by Grant AGL 2013-48980-R, from the Spanish Ministry of Science and Innovation, co-funded by the European Union (FEDER funds).

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