scholarly journals Identification of Divergent Isolates of Banana Mild Mosaic Virus and Development of a New Diagnostic Primer to Improve Detection

Pathogens ◽  
2020 ◽  
Vol 9 (12) ◽  
pp. 1045
Author(s):  
Marwa Hanafi ◽  
Rachid Tahzima ◽  
Sofiene Ben Kaab ◽  
Lucie Tamisier ◽  
Nicolas Roux ◽  
...  

Banana mild mosaic virus (BanMMV) (Betaflexiviridae, Quinvirinae, unassigned species) is a filamentous virus belonging to the Betaflexiviridae family. It infects Musa spp. with a very wide geographic distribution. The genome variability of plant viruses, including the members of the Betaflexiviridae family, makes their molecular detection by specific primers particularly challenging. During routine indexing of the Musa germplasm accessions, a discrepancy was observed between electron microscopy and immunocapture (IC) reverse transcription (RT) polymerase chain reaction (PCR) test results for one asymptomatic accession. Filamentous viral particles were observed while molecular tests failed to amplify any fragment. The accession underwent high-throughput sequencing and two complete genomes of BanMMV with 75.3% of identity were assembled. Based on these sequences and on the 54 coat protein sequences available from GenBank, a new forward primer, named BanMMV CP9, compatible with Poty1, an oligodT reverse primer already used in diagnostics, was designed. A retrospective analysis of 110 different germplasm accessions from diverse origins was conducted, comparing BanMMCP2 and BanMMV CP9 primers. Of these 110 accessions, 16 tested positive with both BanMMCP2 and BanMMV CP9, 3 were positive with only BanMMCP2 and 2 tested positive with only BanMMV CP9. Otherwise, 89 were negative with the two primers and free of flexuous virions. Sanger sequencing was performed from purified PCR products in order to confirm the amplification of the BanMMV sequence for the five accessions with contrasting results. It is highly recommended to use the two primers successively to improve the inclusiveness of the protocol.

Plant Disease ◽  
2011 ◽  
Vol 95 (10) ◽  
pp. 1320-1320 ◽  
Author(s):  
C. Zou ◽  
J. Meng ◽  
Z. Li ◽  
M. Wei ◽  
J. Song ◽  
...  

Yams (Dioscorea spp.) are widely grown in China as vegetables and herbal medicine. However, studies on viral diseases on yams are still limited. As a pilot project of a government initiative for improving yam productivity, a small study was conducted in Guangxi, a southern province of China, on viral disease in yams. Incidence of virus-like disease for the three extensively grown D. alata cultivars, GH2, GH5, and GH6, were 12 to 40%, 12 to 29%, and 11 to 25%, respectively, as found in a field survey with a five-plot sampling method in 2010. A total of 112 leaf samples showing mosaic or mottling or leaves without symptoms were collected from the cvs. GH2, GH5, GH6, and seven additional cultivars (D. alata cvs. GY2, GY23, GY47, GY69, GY62, GY72, and D. batatas cv. Tiegun). To determine if the symptoms were caused by Yam mild mosaic virus (YMMV; genus Potyvirus, family Potyviridae), total RNA was extracted from leaves with a commercial RNA purification kit (TIANGEN, Beijing, China), and reverse-transcription (RT)-PCR was conducted with a YMMV-specific primer pair (4) that amplifies the 3′-terminal portion of the viral genome. A PCR product with the predicted size of 262 bp was obtained from samples of GH5 (number testing positive of total number of leaves = 5 of 12), GH6 (24 of 42), and GY72 (1 of 1), but not from asymptomatic leaves. PCR products from a GH5 sample (YMMV-Nanning) and a GH6 sample (YMMV-Luzhai) were cloned and sequenced using an ABI PRISM 3770 DNA Sequencer. The two PCR products were 97% identical at nucleotide (nt) level and with the highest homology (89% identity) to a YMMV isolate (GenBank Accession No. AJ305466). To further characterize the isolates, degenerate primers (2) were used to amplify viral genome sequence corresponding to the C-terminal region of the nuclear inclusion protein b (NIb) and the N-terminal region of the coat protein (CP). These 781-nt fragments were sequenced and a new primer, YMMV For1 (5′-TTCATGTCGCACAAAGCAGTTAAG-3′) corresponding to the NIb region, was designed and used together with primer YMMV UTR 1R to amplify a fragment that covers the complete CP region of YMMV by RT-PCR. These 1,278-nt fragments were sequenced (GenBank Accession Nos. JF357962 and JF357963). CP nucleotide sequences of the YMMV-Nanning and YMMV-Luzhai isolates were 94% similar, while amino acid sequences were 99% similar. BLAST searches revealed a nucleotide identity of 82 to 89% and a similarity of 88 to 97% for amino acids to sequences of YMMV isolates (AF548499 and AF548519 and AAQ12304 and BAA82070, respectively) in GenBank. YMMV is known to be prevalent on D. alata in Africa and the South Pacific, and has recently been identified in the Caribbean (1) and Colombia (3). To our knowledge, this is the first report of the natural occurrence of YMMV in China and it may have implications for yam production and germplasm exchange within China. References: (1) M. Bousalem and S. Dallot. Plant Dis. 84:200, 2000. (2) D. Colinet et al. Phytopathology 84:65, 1994. (3) S. Dallot et al. Plant Dis. 85:803, 2001. (4) R. A. Mumford and S. E. Seal. J. Virol. Methods 69:73, 1997.


Plants ◽  
2022 ◽  
Vol 11 (2) ◽  
pp. 226
Author(s):  
Marwa Hanafi ◽  
Wei Rong ◽  
Lucie Tamisier ◽  
Chadi Berhal ◽  
Nicolas Roux ◽  
...  

: The banana mild mosaic virus (BanMMV) (Betaflexiviridae, Quinvirinae, unassigned species) is a filamentous virus that infects Musa spp. and has a very wide geographical distribution. The current BanMMV indexing process for an accession requires the testing of no less than four plants cultivated in a greenhouse for at least 6 months and causes a significant delay for the distribution of the germplasm. We evaluated the sensitivity of different protocols for BanMMV detection from in vitro plants to accelerate the testing process. We first used corm tissues from 137 in vitro plants and obtained a diagnostic sensitivity (DSE) of only 61% when testing four plants per accession. After thermotherapy was carried out to eliminate BanMMV infection, the meristem was recovered and further grown in vitro. The same protocol was evaluated in parallel on the corm tissue surrounding the meristem, as a rapid screening to evaluate virus therapy success, and was compared to the results obtained following the standard protocol. The obtained results showed 28% false negatives when conducting testing from corm tissues, making this protocol unsuitable in routine processes. Furthermore, RT-PCR and high-throughput sequencing (HTS) tests were applied on tissues from the base (n = 39) and the leaves (n = 36). For RT-PCR, the average DSE per sample reached 65% from either the base or leaves. HTS was applied on 36 samples and yielded 100% diagnostic specificity (DSP) and 100% DSE, whatever the sampled tissue, allowing the identification of a new Betaflexiviridae species infecting Musa. These results suggest that a reliable diagnostic of BanMMV from in vitro plants using RT-PCR or HTS technologies might represent an efficient alternative for testing after greenhouse cultivation.


Viruses ◽  
2018 ◽  
Vol 10 (8) ◽  
pp. 416 ◽  
Author(s):  
Carla Varanda ◽  
Patrick Materatski ◽  
Maria Campos ◽  
Maria Clara ◽  
Gustavo Nolasco ◽  
...  

RNA silencing is an important defense mechanism in plants, yet several plant viruses encode proteins that suppress this mechanism. In this study, the genome of the Olive mild mosaic virus (OMMV) was screened for silencing suppressors. The full OMMV cDNA and 5 OMMV open reading frames (ORFs) were cloned into the Gateway binary vector pK7WG2, transformed into Agrobacterium tumefaciens, and agroinfiltrated into N. benthamiana 16C plants. CP and p6 showed suppressor activity, with CP showing significantly higher activity than p6, yet activity that was lower than the full OMMV, suggesting a complementary action of CP and p6. These viral suppressors were then used to induce OMMV resistance in plants based on RNA silencing. Two hairpin constructs targeting each suppressor were agroinfiltrated in N. benthamiana plants, which were then inoculated with OMMV RNA. When silencing of both suppressors was achieved, a significant reduction in viral accumulation and symptom attenuation was observed as compared to those of the controls, as well as to when each construct was used alone, proving them to be effective against OMMV infection. This is the first time that a silencing suppressor was found in a necrovirus, and that two independent proteins act as silencing suppressors in a virus member of the Tombusviridae family.


2018 ◽  
Author(s):  
CMR Varanda ◽  
P Materatski ◽  
MD Campos ◽  
MIE Clara ◽  
G Nolasco ◽  
...  

AbstractRNA silencing is an important defense mechanism in plants, yet several plant viruses encode proteins that suppress it. Here the genome of Olive mild mosaic virus (OMMV) was screened for silencing suppressors using a green fluorescent based transient suppression assay. The full OMMV cDNA and 5 different OMMV open reading frames (ORFs) were cloned into Gateway binary destination vector pK7WG2, transformed into Agrobacterium tumefaciens C58C1 and agroinfiltrated into Nicotiana benthamiana 16C plants. Among all ORFs tested, CP and p6 showed suppressor activity, with CP showing a significant higher activity when compared to p6, yet lower than that of the full OMMV. This suggests that OMMV silencing suppression results from a complementary action of both CP and p6.Such discovery led to the use of those viral suppressors in the development of OMMV resistant plants through pathogen-derived resistance (PDR) based on RNA silencing. Two hairpin constructs targeting each suppressor were agroinfiltrated in N. benthamiana plants which were then inoculated with OMMV RNA. When silencing of both suppressors was achieved, a highly significant reduction in viral accumulation and symptom attenuation was observed as compared to that seen when each construct was used alone, and to the respective controls, thus showing clear effectiveness against OMMV infection. Data here obtained indicate that the use of both OMMV viral suppressors as transgenes is a very efficient and promising approach to obtain plants resistant to OMMV.ImportanceOMMV silencing suppressors were determined. Among all ORFs tested, CP and p6 showed suppressor activity, with CP showing a significant higher activity when compared to p6, yet lower than that of the full OMMV, suggesting a complementary action of both CP and p6 in silencing suppression.This is the first time that a silencing suppressor was found in a necrovirus and that two independent proteins act as silencing suppressors in a member of the Tombusviridae family.When silencing of both suppressors was achieved, a highly significant reduction in viral accumulation and symptom attenuation was observed as compared to that seen when each was used alone, thus showing clear effectiveness against OMMV infection. A high percentage of resistant plants was obtained (60%), indicating that the use of both OMMV viral suppressors as transgenes is a very efficient and promising approach to obtain plants resistant to OMMV.


2014 ◽  
Vol 43 (2) ◽  
pp. 193-196 ◽  
Author(s):  
Z. Perez-Egusquiza ◽  
J. Z. Tang ◽  
L. I. Ward ◽  
J. D. Fletcher

2007 ◽  
Vol 142 (1-2) ◽  
pp. 41-49 ◽  
Author(s):  
Pierre-Yves Teycheney ◽  
Isabelle Acina ◽  
Benham E.L. Lockhart ◽  
Thierry Candresse

Insects ◽  
2021 ◽  
Vol 12 (11) ◽  
pp. 994
Author(s):  
Alina S. Puig ◽  
Sarah Wurzel ◽  
Stephanie Suarez ◽  
Jean-Philippe Marelli ◽  
Jerome Niogret

Theobroma cacao is affected by viruses on every continent where the crop is cultivated, with the most well-known ones belonging to the Badnavirus genus. One of these, cacao mild mosaic virus (CaMMV), is present in the Americas, and is transmitted by several species of Pseudococcidae (mealybugs). To determine which species are associated with virus-affected cacao plants in North America, and to assess their potential as vectors, mealybugs (n = 166) were collected from infected trees in Florida, and identified using COI, ITS2, and 28S markers. The species present were Pseudococcus jackbeardsleyi (38%; n = 63), Maconellicoccus hirsutus (34.3%; n = 57), Pseudococcus comstocki (15.7%; n = 26), and Ferrisia virgata (12%; n = 20). Virus acquisition was assessed by testing mealybug DNA (0.8 ng) using a nested PCR that amplified a 500 bp fragment of the movement protein–coat protein region of CaMMV. Virus sequences were obtained from 34.6 to 43.1% of the insects tested; however, acquisition did not differ among species, X2 (3, N = 166) = 0.56, p < 0.91. This study identified two new mealybug species, P. jackbeardsleyi and M. hirsutus, as potential vectors of CaMMV. This information is essential for understanding the infection cycle of CaMMV and developing effective management strategies.


2021 ◽  
Vol 17 (12) ◽  
pp. e1010108
Author(s):  
Mengfei Ji ◽  
Jinping Zhao ◽  
Kelei Han ◽  
Weijun Cui ◽  
Xinyang Wu ◽  
...  

Jasmonic acid (JA) is a crucial hormone in plant antiviral immunity. Increasing evidence shows that viruses counter this host immune response by interfering with JA biosynthesis and signaling. However, the mechanism by which viruses affect JA biosynthesis is still largely unexplored. Here, we show that a highly conserved chloroplast protein cpSRP54 was downregulated in Nicotiana benthamiana infected by turnip mosaic virus (TuMV). Its silencing facilitated TuMV infection. Furthermore, cpSRP54 interacted with allene oxide cyclases (AOCs), key JA biosynthesis enzymes, and was responsible for delivering AOCs onto the thylakoid membrane (TM). Interestingly, TuMV P1 protein interacted with cpSRP54 and mediated its degradation via the 26S proteosome and autophagy pathways. The results suggest that TuMV has evolved a strategy, through the inhibition of cpSRP54 and its delivery of AOCs to the TM, to suppress JA biosynthesis and enhance viral infection. Interaction between cpSRP54 and AOCs was shown to be conserved in Arabidopsis and rice, while cpSRP54 also interacted with, and was degraded by, pepper mild mosaic virus (PMMoV) 126 kDa protein and potato virus X (PVX) p25 protein, indicating that suppression of cpSRP54 may be a common mechanism used by viruses to counter the antiviral JA pathway.


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