Diverse Partitiviruses From the Phytopathogenic Fungus, Rosellinia necatrix

Abstract

Partitiviruses (dsRNA viruses, family Partitiviridae) are ubiquitously detected in plants and fungi. Although previous surveys suggested their omnipresence in the white root rot fungus, Rosellinia necatrix, 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 R. necatrix strains belonging to 15 new species, for which "Rosellinia necatrix partitivirus 11-Rosellinia necatrix partitivirus 25" were proposed, and 5 previously reported species. The newly identified partitiviruses have been taxonomically placed in two genera, Alphapartitivirus, and Betapartitivirus. Some partitiviruses were transfected into reference strains of the natural host, R. necatrix, and an experimental host, Cryphonectria parasitica, using purified virions. A comparative analysis of resultant transfectants revealed interesting differences and similarities between the RNA accumulation and symptom induction patterns of R. necatrix and C. parasitica. 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.

Establishment of Neurospora crassa as a model organism for fungal virology

“…NiFV1 appears not to be adjusted well to N. crassa . Similar phenomena were observed when virus contents were compared between their original and experimental host fungi 13 , 44 , 49 .…”

Assessment of mycoviral diversity in Pakistani fungal isolates revealed infection by 11 novel viruses of a single strain of Fusarium mangiferae isolate SP1

“…Co-infection by multiple partitivirids alone or with other mycoviruses has also been reported previously in many isolates, including R. necatrix strains. R. necatrix strain W442 is one example that harbours a betapartitivirus (Rosellinia necatrix partitivirus 18) and an alphapartitivirus (Rosellinia necatrix partitivirus 19) belonging to Betapartitivirus and Alphapartitivirus that show different inducing levels of antiviral RNA silencing [5,59]. Also reported is the involvement of partitivirids in hypovirulence of phytopathogenic fungal strains co-infected with viruses from other families [27,60,61].…”

“…For example, an isolate of Fusarium poae was reported to be infected by 16 RNA viruses belonging to 11 families [25], while an isolate of Kickxella alabastrina (the subdivision of Kickxellomycotina) was reported to be co-infected by 11 RNA viruses [14]. Other interesting cases area hypovirulent or a growth-retarded strain of the causal pathogen of Dutch elm disease (Ophiostoma novo-ulmi) or white root rot disease (Rosellinia necatrix) infected by multiple distinct viruses belonging to a single family [5,26]. There seem to be complex virus/virus interactions such as co-infections (which have been intensively explored only in a limited number of cases).…”

Metagenomic Analysis of Marigold: Mixed Infection Including Two New Viruses

“…Viruses in the family Partitiviridae have been shown to infect plants, fungi, and protozoa, and phylogenetic analysis based on amino acid sequences of RdRPs shows all the members cluster into five clades corresponding to the five partitivirus genera, which could be also characterized with the hosts and genome segment and protein lengths [ 55 ]. With the advent of next generation sequencing, many new partitiviruses have been identified in plants, fungi and even insects [ 56 , 57 ]. In this study, a new partitivirus infecting marigold named MCV was discovered and phylogenetic analysis shows that MCV is a member of the genus Deltapartitivirus .…”