scholarly journals Analysis of Mechanisms Involved in the Cucumber mosaic virus Satellite RNA-mediated Transgenic Resistance in Tomato Plants

2004 ◽  
Vol 17 (1) ◽  
pp. 98-108 ◽  
Author(s):  
Fabrizio Cillo ◽  
Mariella M. Finetti-Sialer ◽  
Maria A. Papanice ◽  
Donato Gallitelli

Transgenic tomato (Lycopersicon esculentum Mill. cv. UC82) plants expressing a benign variant of Cucumber mosaic virus satellite RNA (CMV Tfn-satRNA) were generated. The transformed plants did not produce symptoms when challenged with a satRNA-free strain of CMV (CMV-FL). The same plant lines initially were susceptible to necrosis elicited by a CMV strain supporting a necrogenic variant of satRNA (CMV-77), but a phenotype of total recovery from the necrosis was observed in the newly developing leaves. The features of the observed resistance were analyzed and are consistent with two different mechanisms of resistance. In transgenic plants inoculated with CMV-FL strain, the symptomless phenotype was correlated to the down-regulation of CMV by Tfn-satRNA, amplified from the transgene transcripts, as the first resistance mechanism. On the other hand, the delayed resistance to CMV-77 in transgenic tomato lines was mediated by a degradation process that targets satRNAs in a sequence-specific manner. Evidence is provided for a correlation between a reduced accumulation level of transgenic messenger Tfn-satRNA, the accumulation of small (approximately 23 nucleotides) RNAs with sequence homology to satRNAs, the progressively reduced accumulation of 77-satRNA in infected tissues, and the transition in infected plants from diseased to healthy. Thus, events leading to the degradation of satRNA sequences indicate a role for RNA silencing as the second mechanism determining resistance of transgenic tomato lines.

1994 ◽  
Vol 119 (3) ◽  
pp. 642-647 ◽  
Author(s):  
P.B. McGarvey ◽  
M.S. Montasser ◽  
J.M. Kaper

Transgenic tomato plants (Lycopersicon esculentum Mill.) expressing cucumber mosaic virus (CMV) satellite RNA fused to a gene for β-glucuronidase were produced using Agrobacterium-mediated transformation. The R1 progeny of self-crossed R0 plants were challenge-inoculated with virion or RNA preparations of CMV or tomato aspermy virus (TAV). The transgenic plants challenged with CMV-1 showed mild disease symptoms in the first 2 weeks postchallenge followed by a decrease in symptoms, resulting in little difference between the transgenic and uninfected control group by the fourth week. Enzyme-linked immunosorbent assay results showed about a 10-fold decrease in virus accumulation in the transgenic plants compared to controls. Tolerance was evident only in plants that contained the recombinant insert and produced mature unit-length satellite RNA after CMV infection. Plants challenged with TAV showed no significant tolerance to virus-induced symptoms.


1992 ◽  
Vol 83-83 (6-7) ◽  
pp. 679-683 ◽  
Author(s):  
Y. Saito ◽  
T. Komari ◽  
C. Masuta1 ◽  
Y. Hayashi ◽  
T. Kumashiro ◽  
...  

Plant Disease ◽  
1998 ◽  
Vol 82 (4) ◽  
pp. 391-396 ◽  
Author(s):  
John R. Stommel ◽  
Marie E. Tousignant ◽  
Thanda Wai ◽  
Rita Pasini ◽  
Jacobus M. Kaper

Field trials of transgenic tomato plants expressing an ameliorative satellite RNA of cucumber mosaic virus (CMV) were conducted to test the efficacy of satellite-transgenic technology to protect against CMV infection. Three transgenic tomato lines derived from two susceptible genotypes were evaluated over two growing seasons for viral symptoms and titers, satellite RNA expression, and fruit yield. Satellite-transgenic lines exhibited mild or no CMV symptoms and low viral titers relative to nontransformed plants. A significant negative correlation between satellite RNA levels and disease severity was evident in transgenic lines. Total marketable yield of CMV-infected satellite-transgenic lines was 40 to 84% greater than that of CMV-infected parent lines. Importantly, yield of CMV-infected satellite-transgenic lines did not differ significantly from mock-inoculated parent lines. Risk assessment results demonstrated low levels of satellite RNA transmission within the test site and no evidence of satellite RNA-induced damage on surrounding plants.


2016 ◽  
Vol 29 (3) ◽  
pp. 181-186 ◽  
Author(s):  
Peter Palukaitis

Satellite RNAs and satellite viruses are extraviral components that can affect either the pathogenicity, the accumulation, or both of their associated viruses while themselves being dependent on the associated viruses as helper viruses for their infection. Most of these satellite RNAs are noncoding RNAs, and in many cases, have been shown to alter the interaction of their helper viruses with their hosts. In only a few cases have the functions of these satellite RNAs in such interactions been studied in detail. In particular, work on the satellite RNAs of Cucumber mosaic virus and Turnip crinkle virus have provided novel insights into RNAs functioning as noncoding RNAs. These effects are described and potential roles for satellite RNAs in the processes involved in symptom intensification or attenuation are discussed. In most cases, models describing these roles involve some aspect of RNA silencing or its suppression, either directly or indirectly involving the particular satellite RNA.


2002 ◽  
Vol 52 (3) ◽  
pp. 219-223 ◽  
Author(s):  
Tsukasa Nunome ◽  
Fumiyoshi Fukumoto ◽  
Fumihiro Terami ◽  
Kaoru Hanada ◽  
Masashi Hirai

2003 ◽  
Vol 16 (6) ◽  
pp. 467-476 ◽  
Author(s):  
Ping Xu ◽  
Elison B. Blancaflor ◽  
Marilyn J. Roossinck

Cucumber mosaic virus (CMV) D satellite RNA (satRNA) attenuates the symptoms induced by CMV in most plants, but causes leaf epinasty and systemic necrosis in tomato plants, where programmed cell death (PCD) is involved. However, our understanding of the cellular and molecular responses to the infection of CMV D satRNA that result in this lethal disease remains limited. In this article, we show for the first time, by histochemical and molecular analysis, that multiple defense responses are specifically induced in CMV and D satRNA (CMV/D satRNA)-infected tomato plants but not in mock-inoculated or CMV-infected plants. These responses include callose deposition and hydrogen peroxide accumulation in infected plants. Furthermore, the transcription of several tomato defense-related genes (e.g., PR-1a1, PR-1b1, PR-2, and PR-10) were activated, and the expression of tomato PR-5 and some abiotic and biotic stress-responsive genes (e.g., catalase II and tomato analogs of Arabidopsis AtBI-1 and tobacco hsr203j) are enhanced. The activation and increase in expression of these genes is correlated with the appearance of leaf epinasty and the development of systemic necrosis in infected tomato plants, while increased expression of the hsr203j analog precedes the development of any disease symptoms. The spatial and temporal expression patterns of these genes as detected by RNA in situ hybridization point to the involvement of a complex developmental program that accompanies disease development resulting from CMV/D satRNA infection.


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