Diverse Partitiviruses From the Phytopathogenic Fungus, Rosellinia necatrix

Abstract

Partitiviruses (dsRNA viruses, family <i>Partitiviridae</i>) are ubiquitously detected in plants and fungi. Although previous surveys suggested their omnipresence in the white root rot fungus, <i>Rosellinia necatrix</i>, only a few of them have been molecularly and biologically characterized thus far. We report the characterization of a total of 20 partitiviruses from 16 <i>R. necatrix</i> strains belonging to 15 new species, for which "<i>Rosellinia necatrix partitivirus 11</i>-<i>Rosellinia necatrix partitivirus 25</i>" were proposed, and 5 previously reported species. The newly identified partitiviruses have been taxonomically placed in two genera, <i>Alphapartitivirus</i>, and <i>Betapartitivirus</i>. Some partitiviruses were transfected into reference strains of the natural host, <i>R. necatrix</i>, and an experimental host, <i>Cryphonectria parasitica</i>, using purified virions. A comparative analysis of resultant transfectants revealed interesting differences and similarities between the RNA accumulation and symptom induction patterns of <i>R. necatrix</i> and <i>C. parasitica</i>. Other interesting findings include the identification of a probable reassortment event and a quintuple partitivirus infection of a single fungal strain. These combined results provide a foundation for further studies aimed at elucidating mechanisms that underly the differences observed.