Affiliation:
1. Department of Crop Sciences, University of Illinois, Urbana, Illinois, USA
2. Department of Plant Pathology, North Dakota State University, Fargo, North Dakota, USA
3. Monsanto Company, Chesterfield, Missouri, USA
4. United States Department of Agriculture, Agricultural Research Service, Urbana, Illinois, USA
Abstract
ABSTRACT
Mycoviruses can have a marked effect on natural fungal communities and influence plant health and productivity. However, a comprehensive picture of mycoviral diversity is still lacking. To characterize the viromes of five widely dispersed plant-pathogenic fungi,
Colletotrichum truncatum
,
Macrophomina phaseolina
,
Diaporthe longicolla
,
Rhizoctonia solani
, and
Sclerotinia sclerotiorum
, a high-throughput sequencing-based metatranscriptomic approach was used to detect viral sequences. Total RNA and double-stranded RNA (dsRNA) from mycelia and RNA from samples enriched for virus particles were sequenced. Sequence data were assembled
de novo
, and contigs with predicted amino acid sequence similarities to viruses in the nonredundant protein database were selected. The analysis identified 72 partial or complete genome segments representing 66 previously undescribed mycoviruses. Using primers specific for each viral contig, at least one fungal isolate was identified that contained each virus. The novel mycoviruses showed affinity with 15 distinct lineages:
Barnaviridae
,
Benyviridae
,
Chrysoviridae
,
Endornaviridae
,
Fusariviridae
,
Hypoviridae
,
Mononegavirales
,
Narnaviridae
,
Ophioviridae
,
Ourmiavirus
,
Partitiviridae
,
Tombusviridae
,
Totiviridae
,
Tymoviridae
, and
Virgaviridae
. More than half of the viral sequences were predicted to be members of the
Mitovirus
genus in the family
Narnaviridae
, which replicate within mitochondria. Five viral sequences showed strong affinity with three families (
Benyviridae
,
Ophioviridae
, and
Virgaviridae
) that previously contained no mycovirus species. The genomic information provides insight into the diversity and taxonomy of mycoviruses and coevolution of mycoviruses and their fungal hosts.
IMPORTANCE
Plant-pathogenic fungi reduce crop yields, which affects food security worldwide. Plant host resistance is considered a sustainable disease management option but may often be incomplete or lacking for some crops to certain fungal pathogens or strains. In addition, the rising issues of fungicide resistance demand alternative strategies to reduce the negative impacts of fungal pathogens. Those fungus-infecting viruses (mycoviruses) that attenuate fungal virulence may be welcome additions for mitigation of plant diseases. By high-throughput sequencing of the RNAs from 275 isolates of five fungal plant pathogens, 66 previously undescribed mycoviruses were identified. In addition to identifying new potential biological control agents, these results expand the grand view of the diversity of mycoviruses and provide possible insights into the importance of intracellular and extracellular transmission in fungus-virus coevolution.
Funder
National Sclerotinia Initiative
United States Department of Agriculture
Publisher
American Society for Microbiology
Subject
Virology,Insect Science,Immunology,Microbiology