Horizontal and vertical transmission of the hypovirulence-associated mycovirus Fusarium oxysporum f. sp. dianthi virus 1

Abstract

Mycovirus Fusarium oxysporum f. sp. dianthi virus 1 (FodV1) has been recently described infecting isolate Fod 116 of Fusarium oxysporum f. sp. dianthi (Fod). FodV1 is a new member of the family Chrysoviridae, and its genome consists of four dsRNA segments ranging from 2.6 to 3.5 kb. Presence of high levels of FodV1 in its original fungal host correlated with alteration of some phenotypic traits, including virulence. In this work we have analysed if FodV1 can be transferred horizontally to another Fod isolate by hyphal anastomosis, and vertically through conidiation, and if the mycovirus accumulates in the recipient isolate at similar levels that those found in the donor one. Moreover, we have investigated if the new virus-infected isolate reproduces the same phenotypic alterations that the original virus-infected does. Results indicated that FodV1 transfers horizontally between compatible isolates by hyphal anastomosis, reaching a high level of accumulation in the recipient isolate, and vertically during sporogenesis. Presence of FodV1 in the new fungal host reduced the growth rate and altered the morphology of the colony on solid medium, and diminished the conidiation rate in liquid medium. More interestingly, FodV1 induced hypovirulence in its new fungal host. Results contained in this work constitute the basis for further research on the application of mycovirus FodV1 to the control of Fusarium wilt diseases.