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

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.

Metatranscriptomic Analysis Reveals Rich Mycoviral Diversity in Three Major Fungal Pathogens of Rice

“…For example, MoCV1 belongs to the family Chrysoviridae , which not only impairs host growth, but also results in abnormal pigmentation [ 25 ]. Our laboratory previously reported that the infections of R. solani by RsEV1, RsPV2, and RsRV5 resulted in reduced mycelial growth and hypovirulence to rice leaves [ 27 , 28 , 29 ]. However, no hypovirulence-associated mycoviruses have been reported in U. virens so far.…”

“…To our knowledge, only Magnaporthe oryzae partitivirus 2 (MoPV2), Magnaporthe oryzae chrysovirus 1-A, -B, and -D (MoCV1-A, MoCV1-B, and MoCV1-D) can result in reduced growth rates, the decline of pathogenicity, and other phenotypes in the P. oryzae [ 23 , 24 , 25 ]. In R. solani , it was previously reported that Rhizoctonia solani partitivirus 5 (RsPV5), Rhizoctonia solani endornavirus 1 (RsEV1), Rhizoctonia solani partitivirus 2 (RsPV2), and Rhizoctonia solani dsRNA virus 5 (RsRV5) are hypovirulence-associated mycoviruses [ 26 , 27 , 28 , 29 ]. However, less hypoviruses have been reported in U. virens .…”

An Outstandingly Rare Occurrence of Mycoviruses in Soil Strains of the Plant-Beneficial Fungi from the Genus Trichoderma and a Novel Polymycoviridae Isolate

“…Some mycoviruses, such as ThPV2 (14), altered the biomass and spore production by Trichoderma spp. ( 14 , 25 , 28 , 29 ); similar to the effects of Fusarium graminearum virus-china 9 (FgV-ch9) ( 28 ) and Rhizoctonia solani dsRNA virus 5 (RsRV5) ( 29 ) on their hosts.…”

Horizontal and Vertical Transmission of a Mycovirus Closely Related to the Partitivirus RhsV717 That Confers Hypovirulence in Rhizoctonia solani

“…The successful utilization of hypoviruses to control chestnut blight (Cryphonectria parasitica) in Europe has spurred the exploration of mycoviruses with the potential to induce hypovirulence in their plant pathogenic hosts, thereby reducing their pathogenic impact [26]. Notable examples included the ssDNA mycovirus Sclerotinia sclerotiorum hypovirulence-associated DNA virus 1 (SsHADV-1) [22], Rhizoctonia solani partitivirus 2 (RsPV2) infecting R. solani AG-1 IA [27], Sclerotinia sclerotiorum partitivirus 1 (SsPV1/WF-1) isolated from S. sclerotiorum, which induces hypovirulence in its host [28], and Rhizoctonia solani dsRNA virus 5 (RsRV5) isolated from AG-1 IA, which also contributes to decreased host pathogenicity [29], among others.…”