ON THE MECHANISM OF REPLICATION OF VIROIDS, VIRUSOIDS, AND SATELLITE RNAs

Two groups of Cucumber mosaic virus (CMV) satellite RNAs (satRNAs), necrogenic and non-necrogenic, can be differentiated according to the symptoms they cause in tomato plants, a host in which they also differ in fitness. In most other CMV hosts these CMV-satRNA cause similar symptoms. Here, we analyse whether they differ in traits determining their relative fitness in melon plants, in which the two groups of CMV-satRNAs cause similar symptoms. For this, ten necrogenic and ten non-necrogenic field satRNA genotypes were assayed with Fny-CMV as a helper virus. Neither type of CMV-satRNA modified Fny-CMV symptoms, and both types increased Fny-CMV virulence similarly, as measured by decreases in plant biomass and lifespan. Necrogenic and non-necrogenic satRNAs differed in their ability to multiply in melon tissues; necrogenic satRNAs accumulated to higher levels both in single infection and in competition with non-necrogenic satRNAs. Indeed, multiplication of some non-necrogenic satRNAs was undetectable. Transmission between hosts by aphids was less efficient for necrogenic satRNAs as a consequence of a more severe reduction of CMV accumulation in leaves. The effect of CMV accumulation on aphid transmission was not compensated for by differences in satRNA encapsidation efficiency or transmissibility to CMV progeny. Thus, necrogenic and non-necrogenic satRNAs differ in their relative fitness in melon, and trade-offs are apparent between the within-host and between-host components of satRNA fitness. Hence, CMV-satRNAs could have different evolutionary dynamics in CMV host-plant species in which they do not differ in pathogenicity.

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Infectious Clones and Chimerical Recombination of Cucumber Mosaic Virus and its Satellite RNAs

Advanced Topics in Science and Technology in China - Experimental Plant Virology ◽

10.1007/978-3-642-14119-5_3 ◽

2010 ◽

pp. 97-123

Author(s):

Jishuang Chen

Keyword(s):

Cucumber Mosaic Virus ◽

Mosaic Virus ◽

Infectious Clones ◽

Satellite Rnas

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SATELLITE RNAs AND SATELLITE VIRUSES

Encyclopedia of Virology ◽

10.1006/rwvi.1999.0260 ◽

1999 ◽

pp. 1607-1615 ◽

Cited By ~ 5

Author(s):

M.E. Taliansky ◽

P.F. Palukaitis

Keyword(s):

Satellite Rnas ◽

Satellite Viruses

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Long Noncoding RNAs in Plant Viroids and Viruses: A Review

Pathogens ◽

10.3390/pathogens9090765 ◽

2020 ◽

Vol 9 (9) ◽

pp. 765 ◽

Cited By ~ 1

Author(s):

Nipin Shrestha ◽

Józef J. Bujarski

Keyword(s):

Rna Silencing ◽

Rna Virus ◽

Regulation Of Gene Expression ◽

Helper Virus ◽

Viral Origin ◽

Protein Coding ◽

Genomic Rnas ◽

Rolling Circle ◽

Satellite Rnas ◽

Virus Interactions

Infectious long-noncoding (lnc) RNAs related to plants can be of both viral and non-viral origin. Viroids are infectious plant lncRNAs that are not related to viruses and carry the circular, single-stranded, non-coding RNAs that replicate with host enzymatic activities via a rolling circle mechanism. Viroids interact with host processes in complex ways, emerging as one of the most productive tools for studying the functions of lncRNAs. Defective (D) RNAs, another category of lnc RNAs, are found in a variety of plant RNA viruses, most of which are noncoding. These are derived from and are replicated by the helper virus. D RNA-virus interactions evolve into mutually beneficial combinations, enhancing virus fitness via competitive advantages of moderated symptoms. Yet the satellite RNAs are single-stranded and include either large linear protein-coding ss RNAs, small linear ss RNAs, or small circular ss RNAs (virusoids). The satellite RNAs lack sequence homology to the helper virus, but unlike viroids need a helper virus to replicate and encapsidate. They can attenuate symptoms via RNA silencing and enhancement of host defense, but some can be lethal as RNA silencing suppressor antagonists. Moreover, selected viruses produce lncRNAs by incomplete degradation of genomic RNAs. They do not replicate but may impact viral infection, gene regulation, and cellular functions. Finally, the host plant lncRNAs can also contribute during plant-virus interactions, inducing plant defense and the regulation of gene expression, often in conjunction with micro and/or circRNAs.

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Transmissibility of Cucumber mosaic virus by Aphis gossypii Correlates with Viral Accumulation and Is Affected by the Presence of Its Satellite RNA

Phytopathology ◽

10.1094/phyto.2000.90.10.1068 ◽

2000 ◽

Vol 90 (10) ◽

pp. 1068-1072 ◽

Cited By ~ 53

Author(s):

Fernando Escriu ◽

Keith L. Perry ◽

Fernando García-Arenal

Keyword(s):

Cucumber Mosaic Virus ◽

Mosaic Virus ◽

Aphis Gossypii ◽

Natural Populations ◽

Virus Transmission ◽

Negative Effect ◽

Infected Tomato ◽

Satellite Rnas ◽

Viral Accumulation ◽

Test Plants

Satellite RNAs (satRNAs) are associated with Cucumber mosaic virus (CMV) in tomato, most often causing severe epidemics of necrotic plants, and not associated with specific host symptoms. Laboratory studies on virus transmission by the aphid vector Aphis gossypii were performed to better understand the dynamics of field populations of CMV. The presence of satRNAs correlated with lower concentrations of virus in infected plants and with a decrease in the efficiency of transmission from satRNA-infected plants. Both the concentration of virus in CMV-infected tomato and the efficiency of transmission varied more extensively with nonnecrogenic satRNAs than with necrogenic satRNAs. A negative effect of satRNAs on virus accumulation can account, in part, for a decrease in the field transmission and recovery of CMV + satRNAs. Aphids behaved differently and probed less readily on plants infected with CMV + necrogenic satRNAs compared with plants containing non-necrogenic satRNAs. Aphid-mediated satRNA-free CMV infections were observed in test plants when aphids were fed on source plants containing CMV + nonnecrogenic satRNA; no comparable satRNA-free test plants occurred when aphids were fed on source plants containing necrogenic satRNAs. These results indicate that factors associated with transmission can be a determinant in the evolution of natural populations of CMV and its satRNA.

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