scholarly journals A Novel RNA Virus Related to Sobemoviruses Confers Hypovirulence on the Phytopathogenic Fungus Sclerotinia sclerotiorum

Viruses ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 759 ◽  
Author(s):  
Azhar ◽  
Mu ◽  
Huang ◽  
Cheng ◽  
Fu ◽  
...  

Infection by diverse mycoviruses is a common phenomenon in Sclerotinia sclerotiorum. In this study, the full genome of a single-stranded RNA mycovirus, tentatively named Hubei sclerotinia RNA virus 1 (HuSRV1), was determined in the hypovirulent strain 277 of S. sclerotiorum. The HuSRV1 genome is 4492 nucleotides (nt) long and lacks a poly (A) tail at the 3ˊ- terminus. Sequence analyses showed that the HuSRV1 genome contains four putative open reading frames (ORFs). ORF1a was presumed to encode a protein with a conserved protease domain and a transmembrane domain. This protein is 27% identical to the P2a protein encoded by the subterranean clover mottle virus. ORF1b encodes a protein containing a conserved RNA-dependent RNA polymerase (RdRp) domain, which may be translated into a fusion protein by a -1 ribosome frameshift. This protein is 45.9% identical to P2b encoded by the sowbane mosaic virus. ORF2 was found to encode a putative coat protein, which shares 23% identical to the coat protein encoded by the olive mild mosaic virus. ORF3 was presumed to encode a putative protein with an unknown function. Evolutionary relation analyses indicated that HuSRV1 is related to members within Sobemovirus, but forms a unique phylogenetic branch, suggesting that HuSRV1 represents a new member within Solemoviridae. HuSRV1 virions, approximately 30 nm in diameter, were purified from strain 277. The purified virions were successfully introduced into virulent strain Ep-1PNA367, resulting in a new hypovirulent strain, which confirmed that HuSRV1 confers hypovirulence on S. sclerotiorum.

Viruses ◽  
2018 ◽  
Vol 10 (8) ◽  
pp. 432 ◽  
Author(s):  
Fangmin Hao ◽  
Mingde Wu ◽  
Guoqing Li

Here, we characterized a negative single-stranded (−ss)RNA mycovirus, Botrytis cinerea mymonavirus 1 (BcMyV1), isolated from the phytopathogenic fungus Botrytis cinerea. The genome of BcMyV1 is 7863 nt in length, possessing three open reading frames (ORF1–3). The ORF1 encodes a large polypeptide containing a conserved mononegaviral RNA-dependent RNA polymerase (RdRp) domain showing homology to the protein L of mymonaviruses, whereas the possible functions of the remaining two ORFs are still unknown. The internal cDNA sequence (10-7829) of BcMyV1 was 97.9% identical to the full-length cDNA sequence of Sclerotinia sclerotiorum negative stranded RNA virus 7 (SsNSRV7), a virus-like contig obtained from Sclerotinia sclerotiorum metatranscriptomes, indicating BcMyV1 should be a strain of SsNSRV7. Phylogenetic analysis based on RdRp domains showed that BcMyV1 was clustered with the viruses in the family Mymonaviridae, suggesting it is a member of Mymonaviridae. BcMyV1 may be widely distributed in regions where B. cinerea occurs in China and even over the world, although it infected only 0.8% of tested B. cinerea strains.


Plant Disease ◽  
2010 ◽  
Vol 94 (3) ◽  
pp. 372-372 ◽  
Author(s):  
N. L. Robertson ◽  
K. L. Brown

In mid-June 2008, distinct mosaic leaves were observed on a cluster of clover (Trifolium spp.) with light pink and white flowers growing at the edge of a lawn in Palmer, AK. Virus minipurification from leaves of affected clover and protein extractions on a polyacrylamide electrophoresis implicated a ~35-kDa putative coat protein (CP). Subsequent western blots and ELISA with a universal potyvirus antiserum (Agdia Inc., Elkhart, IN) confirmed potyvirus identity. Total RNA extracts (RNeasy Plant Mini Kit, Qiagen Inc., Valencia, CA) from the same plant were used for reverse transcription (RT)-PCR. Three sets of degenerate primers that targeted potyvirus-specific genes, HC-Pro (helper component protease) and CI (cylindrical inclusion protein) and the genomic 3′-terminus that included a partial NIb (nuclear inclusion), CP (coat protein), and UTR (untranslated region), produced the expected PCR segments (~0.7, ~0.7, and ~1.6 kbp, respectively) on 1% agarose gels (1). Direct sequencing of the HC-Pro (GenBank No. GQ181115), CI (GQ181116), and CP (GU126690) segments revealed 98, 97, and 99% nucleotide identities (no gaps), respectively, to Bean yellow mosaic virus (BYMV)-chlorotic spot (CS) strain, GenBank No. AB373203. The next closest BYMV percent identity comparisons decreased to 79% for HC-Pro (GenBank No. DQ641248; BYMV-W), 79% for CI (U47033; BYMV-S) partial genes, and 96% for CP (AB041971; BYMV-P242). Mechanical inoculations of purified virus preparations produced local lesions on Chenopodium amaranticolor Coste & A. Reyn. (2 of 5) and C. quinoa Willd. (6 of 7), and mosaic on Nicotiana benthamiana Domin (5 of 5). BYMV was specifically confirmed on tester plants using a double-antibody sandwich (DAS)-ELISA BYMV (strain 204 and B25) kit (AC Diagnostics, Inc., Fayetteville, AR) as directed. The absence of another potyvirus commonly found in clover, Clover yellow vein virus (ClYVV), was verified in parallel DAS-ELISA ClYVV assays (AC Diagnostics, Inc). The BYMV isolate was maintained in N. benthamiana, and virion or sap extracts inoculated to the following host range (number of infected/total inoculated plants [verified by BYMV ELISA]): Cucumis sativus L. ‘Straight Eight’ (0/5), Gomphrena globosa L. (1/4), Nicotiana clevelandii A. Gray (4/7), Phaseolus vulgaris L. ‘Bountiful’ (1/3), Pisum sativum L. (Germplasm Resources Information Network Accession Nos. -PI 508092 (8/12), -W6 17525 (13/13), -W6 17529 (0/13), -W6 17530 (13/14), -W6 17537 (0/12), -W6 17538 (0/12), and -W6 17539 (0/21), Tetragonia tetragoniodes (2/2), Trifolium pretense L. ‘Altaswede’ (6/10), T. repens L. ‘Pilgrim’ (0/8), and Vicia faba L. (1/3). All infected plants had symptoms ranging from systemic mosaic (T. pretense, P. sativum) to leaf distortions (N. clevelandii, Tetragonia tetragoniodes). Interestingly, the host range and genomic sequences of the BYMV Alaskan strain resemble the BYMV-CS (chlorotic spot) strain that was originally isolated from a diseased red clover (T. pretense) plant in Japan more than 40 years ago (2). Although BYMV occurs worldwide and has a wide host range in dictoyledonous and monocotyledonous plants (3), to our knowledge, this is the first report of a natural occurrence of BYMV in Alaska. The incidence and distribution of BYMV in clover and other plant species are not known in Alaska. References: (1) C. Ha et al. Arch. Virol. 153:36, 2008. (2) H. Kume et al. Mem. Fac. Agric. Hokkaido Univ. 7:449, 1970. (3) S. J. Wylie et al. Plant Dis. 92:1596, 2008.


Plant Disease ◽  
2003 ◽  
Vol 87 (11) ◽  
pp. 1366-1371 ◽  
Author(s):  
Richard C. Larsen ◽  
Walter J. Kaiser ◽  
Stephen D. Wyatt ◽  
Keri L. Buxton-Druffel ◽  
Phillip H. Berger

During the 1999 to 2001 growing seasons, symptoms consisting of mosaic, stunting, yellowing, wilting, shortening of internodes, and phloem discoloration were observed in chickpea (Cicer arietinum) grown in the Department of Chuquisaca in southern Bolivia. In some fields, approximately 10% of the plants exhibited viruslike symptoms and suffered greatly reduced seed yields. Lentil (Lens culinaris) was also observed to be infected but not pea (Pisum sativum) or faba bean (Vicia faba) growing in nearby fields. Infected chickpea tissue reacted positively to the potyvirus group-specific monoclonal antibody (MAb), but there was no serological reaction with antisera to the potyviruses Bean yellow mosaic virus, Clover yellow vein virus, Cowpea aphid-borne mosaic virus, Pea seedborne mosaic virus, Bean common mosaic virus, or Bean common mosaic necrosis virus. Western blots of total protein extracts probed with the potyvirus MAb revealed a single band ca. 32 kDa. Comparative sequence analysis of cDNA clones generated from the putative coat protein gene consisted of 282 amino acids (31.9 kDa) and showed moderate identities of 67, 66, 63, 63, and 61% with the coat proteins of potyviruses Pepper severe mosaic virus, Pepper yellow mosaic virus, Potato virus Y, Plum pox virus, and Pepper mottle virus, respectively. Phylogenetic analysis of the coat protein amino acid sequence revealed that this virus is a unique member of the family Potyviridae and is phylogenetically most closely related to a group of Solanaceae-infecting potyviruses rather than to other legumeinfecting potyviruses. The proposed name for the new causal agent is Chickpea yellow mosaic virus.


2009 ◽  
Vol 83 (11) ◽  
pp. 5796-5805 ◽  
Author(s):  
Chun-Wei Cheng ◽  
Yi-Yuong Hsiao ◽  
Hui-Chuan Wu ◽  
Chi-Mau Chuang ◽  
Jao-Shien Chen ◽  
...  

ABSTRACT Bamboo mosaic virus (BaMV) is a 6.4-kb positive-sense RNA virus belonging to the genus Potexvirus of the family Flexiviridae. The 155-kDa viral replicase, the product of ORF1, comprises an N-terminal S-adenosyl-l-methionine (AdoMet)-dependent guanylyltransferase, a nucleoside triphosphatase/RNA 5′-triphosphatase, and a C-terminal RNA-dependent RNA polymerase (RdRp). To search for cellular factors potentially involved in the regulation of replication and/or transcription of BaMV, the viral RdRp domain was targeted as bait to screen against a leaf cDNA library of Nicotiana benthamiana using a yeast two-hybrid system. A putative methyltransferase (PNbMTS1) of 617 amino acid residues without an established physiological function was identified. Cotransfection of N. benthamiana protoplasts with a BaMV infectious clone and the PNbMTS1-expressing plasmid showed a PNbMTS1 dosage-dependent inhibitory effect on the accumulation of BaMV coat protein. Deletion of the N-terminal 36 amino acids, deletion of a predicted signal peptide or transmembrane segment, or mutations in the putative AdoMet-binding motifs of PNbMTS1 abolished the inhibitory effect. In contrast, suppression of PNbMTS1 by virus-induced gene silencing in N. benthamiana increased accumulation of the viral coat protein as well as the viral genomic RNA. Collectively, PNbMTS1 may function as an innate defense protein against the accumulation of BaMV through an uncharacterized mechanism.


2017 ◽  
Author(s):  
Rashid Aman ◽  
Zahir Ali ◽  
Haroon Butt ◽  
Ahmed Mahas ◽  
Fatima Aljedaani ◽  
...  

AbstractCRISPR/Cas systems confer immunity against invading nucleic acids and phages in bacteria and archaea. CRISPR/Cas13a (known previously as C2c2) is a class 2 type VI-A ribonuclease capable of targeting and cleaving single stranded RNA (ssRNA) molecules of the phage genome. Here, we employ CRISPR/Cas13a to engineer interference with an RNA virus, Turnip Mosaic Virus (TuMV), in plants. CRISPR/Cas13a produced interference against green fluorescent protein (GFP) expressing TuMV in transient assays and stable overexpression lines of Nicotiana benthamiana. crRNAs targeting the HC-Pro and GFP sequences exhibited better interference than those targeting other regions such as coat protein (CP) sequence. Cas13a can also process pre-crRNAs into functional crRNAs. Our data indicate that CRISPR/Cas13a can be used for engineering interference against RNA viruses, providing a potential novel mechanism for RNA-guided immunity against RNA viruses, and for other RNA manipulations in plants.


Plant Disease ◽  
2004 ◽  
Vol 88 (5) ◽  
pp. 574-574 ◽  
Author(s):  
M. A. Guaragna ◽  
R. L. Jordan ◽  
M. L. Putnam

Verbena × hybrida is an ornamental annual used in rock gardens as an edging plant and hanging baskets. It comes in a variety of colors and grows approximately 1.5 to 2.5 cm (6 to 10 inches) high. In the spring of 2002, verbena cv. Lavender Shades plants from California showing leaf mosaic symptoms tested positive for potyvirus using an antigen-coated plate enzyme-linked immunosorbent assay with our genus Potyvirus broad spectrum reacting PTY-1 monoclonal as the detecting antibody (3). The virus was transmitted mechanically to Nicotiana benthamiana by sap inoculation from infected verbena plants. Infected tobacco showed systemic mild mosaic symptoms. Total RNA extractions from infected verbena and tobacco leaves were used in reverse transcription-polymerase chain reaction (RT-PCR) assays with generic potyvirus-specific primers that amplify highly conserved 700-bp or 1,600-bp fragments from the 3′ terminus of most potyviruses. This region includes the 3′ noncoding region (3′NCR) and the potyviral coat protein (CP). The PCR-amplified fragments were cloned by using standard TA cloning procedures and sequenced using dye-terminator chemistry. The cloned nucleotide and putative coat protein amino acid sequences from the infected verbena and tobacco plants were compared with the corresponding regions of other potyviruses. Amino acid comparison of the CP region of the verbena po-tyvirus showed 95 to 96% identity to four pea mosaic strains (PMV) of Bean yellow mosaic virus (BYMV), 85 to 89% identity to 20 other strains of BYMV, 74 to 76% identity with six strains of Clover yellow vein virus (CYVV), and only 50 to 64% identity with 28 other potyviruses. Pairwise comparisons among and between the CP sequences of PMV, BYMV, CYVV, and other potyviruses revealed identities of 92 to 99% for BYMV∷ BYMV, PMV∷PMV, and CYVV∷CYVV; 84 to 89% for BYMV∷ PMV, 69 to 78% for BYMV∷CYVV and PMV∷CYVV, and 50 to 64% for all other potyvirus combinations. Additionally, similar pairwise analysis of the 3′NCR of the verbena potyvirus revealed 98 to 99% identity to PMV strains, 81 to 94% to other BYMVs, 68 to 75% to CYVVs, and 52 to 64% with other potyviruses. Other 3′NCR pairwise comparisons generally revealed the same identity trend as described for the CP. Further serological analysis with our panel of BYMV-specific, BYMV-subgroup, and potyvirus cross-reactive monoclonal antibodies (3) confirmed the designation of the verbena potyvirus isolate as a pea mosaic strain of BYMV. To our knowledge this is the first confirmed report of BYMV-pea mosaic strain in Verbena (1,2). References: (1) Agdia, Inc. Positive Ornamental Plant Samples. Agdia On-line Publication, 2003. (2) A. A. Brunt et al. Verbena hybrida. Plant Viruses Online: Descriptions and Lists from the VIDE Database. Version 20. On-line publication, August 1996. (3) R. L. Jordan, and J. Hammond. J. Gen. Virol. 72:1531, 1991.


2020 ◽  
Vol 6 (1) ◽  
Author(s):  
Zheng Qu ◽  
Huizhang Zhao ◽  
Hongxiang Zhang ◽  
Qianqian Wang ◽  
Yao Yao ◽  
...  

Abstract Plant disease is one of the most important causes of crop losses worldwide. The effective control of plant disease is related to food security. Sclerotinia stem rot (SSR) caused by Sclerotinia sclerotiorum leads to serious yield losses in rapeseed (Brassica napus) production. Hypovirulent strain DT-8 of S. sclerotiorum, infected with Sclerotinia sclerotiorum hypovirulence-associated DNA virus 1 (SsHADV-1), has the potential to control SSR. In this study, we found rapeseed bio-priming with strain DT-8 could significantly decrease the disease severity of SSR and increase yield in the field. After bio-priming, strain DT-8 could be detected on the aerial part of the rapeseed plant. By 16S rRNA gene and internal transcribed spacer (ITS) sequencing technique, the microbiome on different parts of the SSR lesion on bioprimed and non-bioprimed rapeseed stem was determined. The results indicated that SSR and bio-priming treatment could influence the structure and composition of fungal and bacterial communities. Bio-priming treatment could reduce the total abundance of possible plant pathogens and enhance the connectivity and robustness of the interaction network at the genus level. This might be one of the mechanisms that rapeseed bioprimed with strain DT-8 had excellent tolerance on SSR. It might be another possible mechanism of biocontrol and will provide a theoretical guide for agricultural practical production.


2003 ◽  
Vol 77 (18) ◽  
pp. 9750-9757 ◽  
Author(s):  
Yoon Gi Choi ◽  
A. L. N. Rao

ABSTRACT The three genomic and a single subgenomic RNA of brome mosaic virus (BMV), an RNA virus infecting plants, are packaged by a single-coat protein (CP) into three morphologically indistinguishable icosahedral virions with T = 3 quasi-symmetry. Genomic RNAs 1 and 2 are packaged individually into separate particles whereas genomic RNA3 and subgenomic RNA4 (coat protein mRNA) are copackaged into a single particle. We report here that packaging of dicistronic RNA3 requires a bipartite signal. A highly conserved 3′ tRNA-like structure postulated to function as a nucleating element (NE) for CP subunits (Y. G. Choi, T. W. Dreher, and A. L. N. Rao, Proc. Natl. Acad. Sci. USA 99:655-660, 2002) and a cis-acting, position-dependent packaging element (PE) of 187 nt present in the nonstructural movement protein gene are the integral components of the packaging core. Efficient incorporation into BMV virions of nonviral RNA chimeras containing NE and the PE provides confirmatory evidence that these two elements are sufficient to direct packaging. Analysis of virion RNA profiles obtained from barley protoplasts transfected with a RNA3 variant lacking the PE provides the first genetic evidence that de novo synthesized RNA4 is incompetent for autonomous assembly whereas prior packaging of RNA3 is a prerequisite for RNA4 to copackage.


2001 ◽  
Vol 75 (11) ◽  
pp. 5385-5390 ◽  
Author(s):  
Yasushi Okinaka ◽  
Kazuyuki Mise ◽  
Eri Suzuki ◽  
Tetsuro Okuno ◽  
Iwao Furusawa

ABSTRACT To investigate the functional domains of the coat protein (CP; 189 amino acids) of Brome mosaic virus, a plant RNA virus, 19 alanine-scanning mutants were constructed and tested for their infectivity in barley and Nicotiana benthamiana. Despite its apparent normal replicative competence and CP production, the C-terminal mutant F184A produced no virions. Furthermore, virion-forming C-terminal mutants P178A and D182A failed to move from cell to cell in both plant species, and mutants D181A and V187A showed host-specific movement. These results indicate that the C-terminal region of CP plays some important roles in virus movement and encapsidation. The specificity of certain mutations for viral movement in two different plant species is evidence for the involvement of host-specific factors.


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