Publications by authors named "Lakha Salaipeth"

8 Publications

  • Page 1 of 1

Infection of Two Heterologous Mycoviruses Reduces the Virulence of , a Fungal Agent of Apple Valsa Canker Disease.

Front Microbiol 2021 25;12:659210. Epub 2021 May 25.

State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Xianyang, China.

Mycovirus infection has been widely shown to attenuate the virulence of phytopathogenic fungi. is an agriculturally important fungus that causes Valsa canker disease in apple trees. In this study, two unrelated mycoviruses [ 1 (CHV1, genus , and single-stranded RNA) and Mycoreovirus 1 (MyRV1, genus , double-stranded RNA)] that originated from (chestnut blight fungus) were singly or doubly introduced into via protoplast fusion. CHV1 and MyRV1 stably infected and caused a reduction in fungal vegetative growth and virulence. Co-infection of both viruses further reduced the virulence of but compromised the stability of CHV1 infection and horizontal transmission through hyphal anastomosis. Infections of MyRV1 and, to a lesser extent, CHV1 up-regulated the transcript expression of RNA silencing-related genes in . The accumulation of CHV1 (but not MyRV1) was elevated by the knockdown of , a key gene of the RNA silencing pathway. Similarly, the accumulation of CHV1 and the efficiency of the horizontal transmission of CHV1 during co-infection was restored by the knockdown of . Thus, CHV1 and MyRV1 are potential biological control agents for apple Valsa canker disease, but co-infection of both viruses has a negative effect on CHV1 infection in due to the activation of antiviral RNA silencing by MyRV1 infection.
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http://dx.doi.org/10.3389/fmicb.2021.659210DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8186502PMC
May 2021

Identification of Viruses and Viroids Infecting Tomato and Pepper Plants in Vietnam by Metatranscriptomics.

Int J Mol Sci 2020 Oct 13;21(20). Epub 2020 Oct 13.

Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul 08826, Korea.

Tomato ( L.) and pepper ( L.) plants belonging to the family are cultivated worldwide. The rapid development of next-generation sequencing (NGS) technology facilitates the identification of viruses and viroids infecting plants. In this study, we carried out metatranscriptomics using RNA sequencing followed by bioinformatics analyses to identify viruses and viroids infecting tomato and pepper plants in Vietnam. We prepared a total of 16 libraries, including eight tomato and eight pepper libraries derived from different geographical regions in Vietnam. We identified a total of 602 virus-associated contigs, which were assigned to 18 different virus species belonging to nine different viral genera. We identified 13 different viruses and two viroids infecting tomato plants and 12 viruses and two viroids infecting pepper plants with viruses as dominantly observed pathogens. Our results showed that multiple infection of different viral pathogens was common in both plants. Moreover, geographical region and host plant were two major factors to determine viral populations. Taken together, our results provide the comprehensive overview of viral pathogens infecting two important plants in the family grown in Vietnam.
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http://dx.doi.org/10.3390/ijms21207565DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7593927PMC
October 2020

Identification of a Novel Hypovirulence-Inducing Hypovirus From .

Front Microbiol 2019 15;10:1076. Epub 2019 May 15.

State Key Laboratory of Crop Stress Biology for Arid Areas and College of Plant Protection, Northwest A&F University, Yangling, China.

Mycoviruses are wide spread throughout almost all groups of fungi but only a small number of mycoviruses can attenuate the growth and virulence of their fungal hosts. is an ascomycete fungus that causes leaf spot diseases on various crop plants. In this study, we identified a novel ssRNA mycovirus infecting an f. sp. strain isolated from an apple orchard in China. Sequence analyses revealed that this virus is related to hypoviruses, in particular to Wuhan insect virus 14, an unclassified hypovirus identified from insect meta-transcriptomics, as well as other hypoviruses belonging to the genus , and therefore this virus is designed as Alternaria alternata hypovirus 1 (AaHV1). The genome of AaHV1 contains a single large open-reading frame encoding a putative polyprotein (∼479 kDa) with a cysteine proteinase-like and replication-associated domains. Curing AaHV1 from the fungal host strain indicated that the virus is responsible for the slow growth and reduced virulence of the host. AaHV1 defective RNA (D-RNA) with internal deletions emerging during fungal subcultures but the presence of D-RNA does not affect AaHV1 accumulation and pathogenicities. Moreover, AaHV1 could replicate and confer hypovirulence in , a fungal pathogen of apple white rot disease. This finding could facilitate better understanding of pathogenicity and is relevant for development of biocontrol methods of fungal diseases.
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http://dx.doi.org/10.3389/fmicb.2019.01076DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6530530PMC
May 2019

Phytopathogenic fungus hosts a plant virus: A naturally occurring cross-kingdom viral infection.

Proc Natl Acad Sci U S A 2017 11 30;114(46):12267-12272. Epub 2017 Oct 30.

State Key Laboratory of Crop Stress Biology for Arid Areas and College of Plant Protection, Northwest A&F University, Yangling, 712100, China;

The transmission of viral infections between plant and fungal hosts has been suspected to occur, based on phylogenetic and other findings, but has not been directly observed in nature. Here, we report the discovery of a natural infection of the phytopathogenic fungus by a plant virus, cucumber mosaic virus (CMV). The CMV-infected strain was obtained from a potato plant growing in Inner Mongolia Province of China, and CMV infection was stable when this fungal strain was cultured in the laboratory. CMV was horizontally transmitted through hyphal anastomosis but not vertically through basidiospores. By inoculation via protoplast transfection with virions, a reference isolate of CMV replicated in and another phytopathogenic fungus, suggesting that some fungi can serve as alternative hosts to CMV. Importantly, in fungal inoculation experiments under laboratory conditions, could acquire CMV from an infected plant, as well as transmit the virus to an uninfected plant. This study presents evidence of the transfer of a virus between plant and fungus, and it further expands our understanding of plant-fungus interactions and the spread of plant viruses.
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http://dx.doi.org/10.1073/pnas.1714916114DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5699089PMC
November 2017

Megabirnavirus structure reveals a putative 120-subunit capsid formed by asymmetrical dimers with distinctive large protrusions.

J Gen Virol 2015 Aug 12;96(8):2435-2441. Epub 2015 May 12.

Institute of Plant Science and Resources, Okayama University, Kurashiki, Okayama, 710-0046, Japan.

Rosellinia necatrix megabirnavirus 1 (RnMBV1) W779 is a bi-segmented dsRNA virus and a strain of the type species Rosellinia necatrix megabirnavirus 1 of the family Megabirnaviridae. RnMBV1 causes severe reduction of both mycelial growth of Rosellinia necatrix in synthetic medium and fungal virulence to plant hosts, and thus has strong potential for virocontrol (biological control using viruses) of white rot. The structure of RnMBV1 was examined by cryo-electron microscopy and three-dimensional reconstruction at 15.7 Å resolution. The diameter of the RnMBV1 capsid was 520 Å, and the capsid was composed of 60 asymmetrical dimers in the T = 1 (so-called T = 2) lattice that is well conserved among dsRNA viruses. However, RnMBV1 has putatively 120 large protrusions with a width of ∼ 45 Å and a height of ∼ 50 Å on the virus surface, making it distinguishable from the other dsRNA viruses.
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http://dx.doi.org/10.1099/vir.0.000182DOI Listing
August 2015

Genome rearrangement of a mycovirus Rosellinia necatrix megabirnavirus 1 affecting its ability to attenuate virulence of the host fungus.

Virology 2014 Feb 14;450-451:308-15. Epub 2014 Jan 14.

Institute of Plant Science and Resources, Okayama University, Kurashiki, Okayama 710-0046, Japan.

Rosellinia necatrix megabirnavirus 1 (RnMBV1) is a bi-segmented double-stranded RNA mycovirus that reduces the virulence of the fungal plant pathogen R. necatrix. We isolated strains of RnMBV1 with genome rearrangements (RnMBV1-RS1) that retained dsRNA1, encoding capsid protein (ORF1) and RNA-dependent RNA polymerase (ORF2), and had a newly emerged segment named dsRNAS1, but with loss of dsRNA2, which contains two ORFs of unknown function. Analyses of two variants of dsRNAS1 revealed that they both originated from dsRNA1 by deletion of ORF1 and partial tandem duplication of ORF2, retaining a much shorter 5' untranslated region (UTR). R. necatrix transfected with RnMBV-RS1 virions showed maintenance of virulence on host plants compared with infection with RnMBV1. This suggests that dsRNAS1 is able to be transcribed and packaged, as well as suggesting that dsRNA2, while dispensable for virus replication, is required to reduce the virulence of R. necatrix.
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http://dx.doi.org/10.1016/j.virol.2013.12.002DOI Listing
February 2014

Biological properties and expression strategy of rosellinia necatrix megabirnavirus 1 analysed in an experimental host, Cryphonectria parasitica.

J Gen Virol 2014 Mar 20;95(Pt 3):740-750. Epub 2013 Nov 20.

Institute of Plant Science and Resources, Okayama University, Kurashiki, Okayama 710-0046, Japan.

Rosellinia necatrix megabirnavirus 1 (RnMBV1) with a bipartite dsRNA genome (dsRNA1 and dsRNA2) confers hypovirulence to its natural host, the white root rot fungus, and is thus regarded as a potential virocontrol (biocontrol) agent. Each segment has two large ORFs: ORF1 and partially overlapping ORF2 on dsRNA1 encode the major capsid protein (CP) and RNA-dependent RNA polymerase (RdRp), whilst ORF3 and ORF4 on dsRNA2 encode polypeptides with unknown functions. Here, we report the biological and molecular characterization of this virus in the chestnut blight fungus, Cryphonectria parasitica, a filamentous fungus that has been used as a model for mycovirus research. Transfection with purified RnMBV1 particles into an RNA-silencing-defective strain (Δdcl-2) of C. parasitica and subsequent anastomosis with the WT strain (EP155) resulted in stable persistent infection in both host strains. However, accumulation levels in the two strains were different, being ~20-fold higher in Δdcl-2 than in EP155. Intriguingly, whilst RnMBV1 reduced both virulence and growth rate in Δdcl-2, it attenuated virulence without affecting significantly other traits in EP155. Western blot analysis using antiserum against recombinant proteins encoded by either ORF1 or ORF2 demonstrated the presence of a 250 kDa protein in purified virion preparations, suggesting that RdRp is expressed as a CP fusion product via a -1 frameshift. Antiserum against the ORF3-encoded protein allowed the detection of 150, 30 and 23 kDa polypeptides specifically in RnMBV1-infected mycelia. Some properties of an RnMBV1 mutant with genome rearrangements, which occurred after transfection of Δdcl-2 and EP155, were also presented. This study provides an additional example of C. parasitica serving as a versatile, heterologous fungus for exploring virus-host interactions and virus gene expression strategies.
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http://dx.doi.org/10.1099/vir.0.058164-0DOI Listing
March 2014

A novel bipartite double-stranded RNA Mycovirus from the white root rot Fungus Rosellinia necatrix: molecular and biological characterization, taxonomic considerations, and potential for biological control.

J Virol 2009 Dec 14;83(24):12801-12. Epub 2009 Oct 14.

Agrivirology Laboratory, Research Institute for Bioresources, Okayama University, Kurashiki, Okayama 710-0046, Japan.

White root rot, caused by the ascomycete Rosellinia necatrix, is a devastating disease worldwide, particularly in fruit trees in Japan. Here we report on the biological and molecular properties of a novel bipartite double-stranded RNA (dsRNA) virus encompassing dsRNA-1 (8,931 bp) and dsRNA-2 (7,180 bp), which was isolated from a field strain of R. necatrix, W779. Besides the strictly conserved 5' (24 nt) and 3' (8 nt) terminal sequences, both segments show high levels of sequence similarity in the long 5' untranslated region of approximately 1.6 kbp. dsRNA-1 and -2 each possess two open reading frames (ORFs) named ORF1 to -4. Although the protein encoded by 3'-proximal ORF2 on dsRNA-1 shows sequence identities of 22 to 32% with RNA-dependent RNA polymerases from members of the families Totiviridae and Chrysoviridae, the remaining three virus-encoded proteins lack sequence similarities with any reported mycovirus proteins. Phylogenetic analysis showed that the W779 virus belongs to a separate clade distinct from those of other known mycoviruses. Purified virions approximately 50 nm in diameter consisted of dsRNA-1 and -2 and a single major capsid protein of 135 kDa, which was shown by peptide mass fingerprinting to be encoded by dsRNA-1 ORF1. We developed a transfection protocol using purified virions to show that the virus was responsible for reduction of virulence and mycelial growth in several host strains. These combined results indicate that the W779 virus is a novel bipartite dsRNA virus with potential for biological control (virocontrol), named Rosellinia necatrix megabirnavirus 1 (RnMBV1), that possibly belongs to a new virus family.
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http://dx.doi.org/10.1128/JVI.01830-09DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2786845PMC
December 2009
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