Genome Organizations and Functional Analyses of a Novel Gammapartitivirus from Rhizoctonia solani AG-1 IA Strain D122.

Meiling Zhang,Zhenrui He,Erxun Zhou,Xiaotong Huang,Canwei Shu

doi:10.3390/v13112254

Meiling Zhang, Zhenrui He + Show 3 more

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https://doi.org/10.3390/v13112254

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Abstract

Here, we describe a novel double-stranded (ds) RNA mycovirus designated Rhizoctonia solani dsRNA virus 5 (RsRV5) from strain D122 of Rhizoctonia solani AG-1 IA, the causal agent of rice sheath blight. The RsRV5 genome consists of two segments of dsRNA (dsRNA-1, 1894 bp and dsRNA-2, 1755 bp), each possessing a single open reading frame (ORF). Sequence alignments and phylogenetic analyses showed that RsRV5 is a new member of the genus Gammapartitivirus in the family Partitiviridae. Transmission electron microscope (TEM) images revealed that RsRV5 has isometric viral particles with a diameter of approximately 20 nm. The mycovirus RsRV5 was successfully removed from strain D122 by using the protoplast regeneration technique, thus resulting in derivative isogenic RsRV5-cured strain D122-P being obtained. RsRV5-cured strain D122-P possessed the traits of accelerated mycelial growth rate, increased sclerotia production and enhanced pathogenicity to rice leaves compared with wild type RsRV5-infection strain D122. Transcriptome analysis showed that three genes were differentially expressed between two isogenic strains, D122 and D122-P. These findings provided new insights into the molecular mechanism of the interaction between RsRV5 and its host, D122 of R. solani AG-1 IA.

Highlights

Mycovirus-associated hypovirulent traits of plant pathogenic fungi are important biocontrol resources for the control of plant fungal diseases, e.g., the +single-stranded RNA (ssRNA) mycovirus Cryphonectria hypovirus 1 (CHV1) against chestnut blight caused by Cryphonectria parasitica [7], and the control of rapeseed stem rot caused by Sclerotinia sclerotiorum with Sclerotinia sclerotiorum hypovirulence-associated DNA virus 1 (SsHADV-1) [8]
We observed that strain D122 produced far fewer sclerotia on potato dextrose agar (PDA) compared to a typical strain GD118 of R. solani AG-1 IA
ToTo investigate whether the the mycovirus was was responsible for this growth, we investigate whether mycovirus responsible forimpaired this impaired growth, first to eliminate it fromitthe fungal by host hyphal and ribavirin treatweattempted first attempted to eliminate from the host fungal by tipping hyphal tipping and ribavirin treatment

Summary

Introduction

Most mycoviruses possess either doublestranded RNA (dsRNA) genomes or positive sense (+) single-stranded RNA (ssRNA). Genomes, and some have negative-sense (−) ssRNA or single-stranded DNA (ssDNA). Many mycoviruses do not cause any visible abnormal symptoms in their fungal and oomycete hosts, a few can reduce their hosts’ pathogenicity. This phenomenon is known as hypovirulence [2,7]. Mycovirus-associated hypovirulent traits of plant pathogenic fungi are important biocontrol resources for the control of plant fungal diseases, e.g., the +ssRNA mycovirus Cryphonectria hypovirus 1 (CHV1) against chestnut blight caused by Cryphonectria parasitica [7], and the control of rapeseed stem rot caused by Sclerotinia sclerotiorum with Sclerotinia sclerotiorum hypovirulence-associated DNA virus 1

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