scholarly journals Antiviral RNA Silencing Is Restricted to the Marginal Region of the Dark Green Tissue in the Mosaic Leaves of Tomato Mosaic Virus-Infected Tobacco Plants

2008 ◽  
Vol 82 (7) ◽  
pp. 3250-3260 ◽  
Author(s):  
Katsuyuki Hirai ◽  
Kenji Kubota ◽  
Tomofumi Mochizuki ◽  
Shinya Tsuda ◽  
Tetsuo Meshi
Keyword(s):  
Mosaic Virus ◽  
Rna Silencing ◽  
Tomato Mosaic Virus ◽  
Common Disease ◽  
Tobacco Plants ◽  
Systemic Spread ◽  
Green Tissue ◽  
Green Areas ◽  
Dark Green ◽  
Infected Tobacco

ABSTRACT Mosaic is a common disease symptom caused by virus infection in plants. Mosaic leaves of Tomato mosaic virus (ToMV)-infected tobacco plants consist of yellow-green and dark green tissues that contain large and small numbers of virions, respectively. Although the involvement of RNA silencing in mosaic development has been suggested, its role in the process that results in an uneven distribution of the virus is unknown. Here, we investigated whether and where ToMV-directed RNA silencing was established in tobacco mosaic leaves. When transgenic tobaccos defective in RNA silencing were infected with ToMV, little or no dark green tissue appeared, implying the involvement of RNA silencing in mosaic development. ToMV-related small interfering RNAs were rarely detected in the dark green areas of the first mosaic leaves, and their interior portions were susceptible to infection. Thus, ToMV-directed RNA silencing was not effective there. By visualizing the cells where ToMV-directed RNA silencing was active, it was found that the effective silencing occurs only in the marginal regions of the dark green tissue (∼0.5 mm in width) and along the major veins. Further, the cells in the margins were resistant against recombinant potato virus X carrying a ToMV-derived sequence. These findings demonstrate that RNA silencing against ToMV is established in the cells located at the margins of the dark green areas, restricting the expansion of yellow-green areas, and consequently defines the mosaic pattern. The mechanism of mosaic symptom development is discussed in relation to the systemic spread of the virus and RNA silencing.

scholarly journals The 2b protein of cucumber mosaic virus is essential for viral infection of the shoot apical meristem and for efficient invasion of leaf primordia in infected tobacco plants

2009 ◽  
Vol 90 (12) ◽  
pp. 3015-3021 ◽  
Author(s):  
Anurag Sunpapao ◽  
Takashi Nakai ◽  
Fang Dong ◽  
Tomofumi Mochizuki ◽  
Satoshi T. Ohki
Keyword(s):  
Cucumber Mosaic Virus ◽  
Mosaic Virus ◽  
Shoot Apical Meristem ◽  
Rna Silencing ◽  
Apical Meristem ◽  
Leaf Primordia ◽  
Shoot Meristem ◽  
Tobacco Plants ◽  
2B Protein ◽  
Infected Tobacco

It has been reported previously that a 2b protein-defective mutant of the cucumber mosaic virus (CMV) Pepo strain (Δ2b) induces only mild symptoms in systemically infected tobacco plants. To clarify further the role of the 2b protein as an RNA silencing suppressor in mosaic symptom expression during CMV infection, this study monitored the sequential distribution of Δ2b in the shoot meristem and leaf primordia (LP) of inoculated tobacco. Time-course histochemical observations revealed that Δ2b was distributed in the shoot meristem at 7 days post-inoculation (p.i.), but could not invade shoot apical meristem (SAM) and quickly disappeared from the shoot meristem, whereas wild-type (Pepo) transiently appeared in SAM from 4 to 10 days p.i. In LP, Δ2b signals were detected only at 14 and 21 days p.i., whereas dense Pepo signals were observed in LP from 4 to 18 days p.i. Northern blot analysis showed that small interfering RNA (siRNA) derived from Δ2b RNA accumulated earlier in the shoot meristem and LP than that of Pepo. However, a similar amount of siRNA was detected in both Pepo- and Δ2b-infected plants at late time points. Tissue printing analysis of the inoculated leaves indicated that the areas infected by Pepo increased faster than those infected by Δ2b, whereas accumulation of Δ2b in protoplasts was similar to that of Pepo. These findings suggest that the 2b protein of the CMV Pepo strain determines virulence by facilitating the distribution of CMV in the shoot meristem and LP via prevention of RNA silencing and/or acceleration of cell-to-cell movement.

The coat protein of Tomato mosaic virus L11Y is associated with virus-induced chlorosis on infected tobacco plants

2009 ◽  
Vol 75 (4) ◽  
pp. 297-306 ◽  
Author(s):  
Jun Ohnishi ◽  
Katsuyuki Hirai ◽  
Ayami Kanda ◽  
Tomio Usugi ◽  
Tetsuo Meshi ◽  
...  
Keyword(s):  
Coat Protein ◽  
Mosaic Virus ◽  
Tomato Mosaic Virus ◽  
Tobacco Plants ◽  
Infected Tobacco

scholarly journals First Report of Tomato Brown Rugose Fruit Virus Infecting Tomato Crop in Saudi Arabia

Plant Disease ◽  
2021 ◽  
Author(s):  
Ahmed Sabra ◽  
Mohammed Ali Al Saleh ◽  
I. M. Alshahwan ◽  
Mahmoud A. Amer
Keyword(s):  
Saudi Arabia ◽  
Mosaic Virus ◽  
Solanum Lycopersicum ◽  
Tomato Mosaic Virus ◽  
Enzyme Linked Immunosorbent Assay ◽  
Rt Pcr ◽  
First Report ◽  
Pcr Products ◽  
Dark Green ◽  
Leaf Symptoms

Tomato (Solanum lycopersicum L.) is the most economically important member of family Solanaceae and cultivated worldwide and one of the most important crops in Saudi Arabia. The aim of this study is screening of the most common viruses in Riyadh region and identified the presence of tomato brown rugose fruit virus (ToBRFV) in Saudi Arabia. In January 2021, unusual fruit and leaf symptoms were observed in several greenhouses cultivating tomatoes commercially in Riyadh Region, Saudi Arabia. Fruit symptoms showed irregular brown spots, deformation, and yellowing spots which render the fruits non-marketable, while the leaf symptoms included mottling, mosaic with dark green wrinkled and narrowing. These plants presented the symptoms similar to those described in other studies (Salem et al., 2015, Luria et al., 2017). A total 45 Symptomatic leaf samples were collected and tested serologically against suspected important tomato viruses including: tomato chlorosis virus, tomato spotted wilt virus, tomato yellow leaf curl virus, tomato chlorotic spot virus, tomato aspermy virus, tomato bushy stunt virus, tomato black ring virus, tomato ringspot virus, tomato mosaic virus, pepino mosaic virus and ToBRFV using Enzyme linked immunosorbent assay (ELISA) test (LOEWE®, Biochemica, Germany), according to the manufacturers' instructions. The obtained results showed that 84.4% (38/45) of symptomatic tomato samples were infected with at least one of the detected viruses. The obtained results showed that 55.5% (25/45) of symptomatic tomato samples were found positive to ToBRFV, three out of 25 samples (12%) were singly infected, however 22 out of 45 (48.8%) had mixed infection between ToBRFV and with at least one of tested viruses. A sample with a single infection of ToBRFV was mechanically inoculated into different host range including: Chenopodium amaranticolor, C. quinoa, C. album, C. glaucum, Nicotiana glutinosa, N. benthamiana, N. tabacum, N. occidentalis, Gomphrena globosa, Datura stramonium, Solanum lycopersicum, S. nigrum, petunia hybrida and symptoms were observed weekly and the systemic presence of the ToBRFV was confirmed by RT-PCR and partial nucleotide sequence. A Total RNA was extracted from DAS-ELISA positive samples using Thermo Scientific GeneJET Plant RNA Purification Mini Kit. Reverse transcription-Polymerase chain reaction (RT-PCR) was carried out using specific primers F-3666 (5´-ATGGTACGAACGGCGGCAG-3´) and R-4718 (5´-CAATCCTTGATGTG TTTAGCAC-3´) which amplified a fragment of 1052 bp of Open Reading Frame (ORF) encoding the RNA-dependent RNA polymerase (RdRp). (Luria et al. 2017). RT-PCR products were analyzed using 1.5 % agarose gel electrophoresis. RT-PCR products were sequenced in both directions by Macrogen Inc. Seoul, South Korea. Partial nucleotide sequences obtained from selected samples were submitted to GenBank and assigned the following accession numbers: MZ130501, MZ130502, and MZ130503. BLAST analysis of Saudi isolates of ToBRFV showed that the sequence shared nucleotide identities ranged between 98.99 % to 99.50 % among them and 98.87-99.87 % identity with ToBRFV isolates from Palestine (MK881101 and MN013187), Turkey (MK888980, MT118666, MN065184, and MT107885), United Kingdom (MN182533), Egypt (MN882030 and MN882031), Jordan (KT383474), USA (MT002973), Mexico (MK273183 and MK273190), Canada (MN549395) and Netherlands (MN882017, MN882018, MN882042, MN882023, MN882024, and MN882045). To our knowledge, this is the first report of occurrence of ToBRFV infecting tomato in Saudi Arabia which suggests its likely introduction by commercial seeds from countries reported this virus and spread in greenhouses through mechanical means. The author(s) declare no conflict of interest. Keywords: Tomato brown rugose fruit virus, tomato, ELISA, RT-PCR, Saudi Arabia References: Luria N, et al., 2017. PLoS ONE 12(1): 1-19. Salem N, et al., 2015. Archives of Virology 161(2): 503-506. Fig. 1. Symptoms caused by ToBRFV showing irregular brown spots, deformation, yellowing spots on fruits (A, B, C) and bubbling and mottling, mosaic with dark green wrinkled and narrowing on leaf (D).

scholarly journals Overexpression of a host factor TOM1 inhibits tomato mosaic virus propagation and suppression of RNA silencing

Virology ◽  
2008 ◽  
Vol 376 (1) ◽  
pp. 132-139 ◽  
Author(s):  
Yuka Hagiwara-Komoda ◽  
Katsuyuki Hirai ◽  
Atsuko Mochizuki ◽  
Masamichi Nishiguchi ◽  
Tetsuo Meshi ◽  
...  
Keyword(s):  
Mosaic Virus ◽  
Rna Silencing ◽  
Host Factor ◽  
Tomato Mosaic Virus ◽  
Virus Propagation

scholarly journals The Suppressor of Transgene RNA Silencing Encoded by Cucumber mosaic virus Interferes with Salicylic Acid-Mediated Virus Resistance

2001 ◽  
Vol 14 (6) ◽  
pp. 715-724 ◽  
Author(s):  
Liang-Hui Ji ◽  
Shou-Wei Ding
Keyword(s):  
Salicylic Acid ◽  
Cucumber Mosaic Virus ◽  
Mosaic Virus ◽  
Virus Resistance ◽  
Rna Silencing ◽  
Defense Mechanism ◽  
Antiviral Defense ◽  
Oxidase Gene ◽  
Systemic Spread ◽  
Systemic Infections

The Cucumber mosaic virus (CMV)-encoded 2b protein (Cmv2b) is a nuclear protein that suppresses transgene RNA silencing in Nicotiana benthamiana. Cmv2b is an important virulence determinant but nonessential for systemic spread in N. glutinosa, in contrast to its indispensable role for systemic infections in cucumber. Here, we report that Cmv2b became essential for systemic infections in older N. glutinosa plants or in young seedlings pre-treated with salicylic acid (SA). Expression of Cmv2b from the genome of either CMV or Tobacco mosaic virus significantly reduced the inhibitory effect of SA on virus accumulation in inoculated leaves and systemic leaves. A close correlation is demonstrated between Cmv2b expression and a reduced SA-dependent induction of the alternative oxidase gene, a component of the recently proposed SA-regulated antiviral defense. These results collectively reveal a novel activity of Cmv2b in the inhibition of SA-mediated virus resistance. We used a N. tabacum line expressing a bacterial nahG transgene that degrades SA to provide evidence for a Cmv2b-sensitive antiviral defense mechanism in tobacco in which SA acts as a positive modifier but not as an essential component. We propose that SA induces virus resistance by potentiating a RNA-silencing antiviral defense that is targeted by Cmv2b.

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