scholarly journals Cucumber mosaic virus satellite RNAs that induce similar symptoms in melon plants show large differences in fitness

2011 ◽  
Vol 92 (8) ◽  
pp. 1930-1938 ◽  
Author(s):  
Mónica Betancourt ◽  
Aurora Fraile ◽  
Fernando García-Arenal

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.

2000 ◽  
Vol 90 (5) ◽  
pp. 480-485 ◽  
Author(s):  
Fernando Escriu ◽  
Aurora Fraile ◽  
Fernando García-Arenal

From 1986 to 1992, an epidemic of tomato necrosis caused by Cucumber mosaic virus (CMV) plus CMV satellite RNAs (satRNAs) occurred in eastern Spain. From 1989 onward, the frequency of tomato necrosis di-minshed, and it almost completely disappeared after 1991. Analyses of plants infected with CMV and with CMV satRNA and of the phenotype (necrogenic or nonnecrogenic for tomato) induced by some CMV satRNA variants, showed that the disappearance of tomato necrosis was due to changes in the genetic composition of the satRNA population (i.e., to its evolution toward decreased virulence). Analysis of components of the fitness of satRNA variants, necrogenic or nonnecrogenic for tomato, showed that necrogenic and nonnecrogenic variants did not differ in infectivity or in their accumulation level in tomato and that they represented the same fraction of encapsidated RNA. Other fitness components were positively correlated with the greater virulence of necrogenic variants, in that they were favored in mixed infections with nonnecrogenic variants and were more effectively passed into CMV progeny than were nonnecrogenic variants. On the other hand, necrogenic CMV satRNA variants caused a more pronounced depression in the accumulation of CMV than did nonnecro-genic variants, which could affect the efficiency of aphid transmission. Thus, the evolution of virulence in the CMV satRNA population can be explained by trade-offs between factors that determine virulence and factors that affect transmission, as predicted by theoretical models on the evolution of virulence in parasites.


2002 ◽  
Vol 92 (1) ◽  
pp. 51-58 ◽  
Author(s):  
Yongzeng Wang ◽  
Victor Gaba ◽  
Jie Yang ◽  
Peter Palukaitis ◽  
Amit Gal-On

Mixed infections of cucurbits by Cucumber mosaic virus (CMV) and potyviruses exhibit a synergistic interaction. Zucchini squash and melon plants coinfected by the potyvirus Zucchini yellow mosaic virus (ZYMV) and either Fny-CMV (subgroup IA) or LS-CMV (subgroup II) displayed strong synergistic pathological responses, eventually progressing to vascular wilt and plant death. Accumulation of Fny- or LS-CMV RNAs in a mixed infection with ZYMV in zucchini squash was slightly higher than infection with CMV strains alone. There was an increase in CMV (+) strand RNA levels, but no increase in CMV (-) RNA3 levels during mixed infection with ZYMV. Moreover, only the level of capsid protein from LS-CMV increased in mixed infection. ZYMV accumulated to similar levels in singly and mixed infected zucchini squash and melon plants. Coinfection of squash with the potyvirus Watermelon mosaic virus (WMV) and CMV strains increased both the Fny-CMV RNA levels and the LS-CMV RNA levels. However, CMV (-) strand RNA3 levels were increased little or not at all for CMV on coinfection with WMV. Infection of CMV strains (LS and Fny) containing satellite RNAs (WL47-sat RNA and B5*-sat RNA) reduced the accumulation of the helper virus RNA, except when B5*-sat RNA was mixed with LS- CMV. However, mixed infection containing ZYMV and the CMV strains with satellites reversed the suppression effect of satellite RNAs on helper virus accumulation and increased satellite RNA accumulation. The synergistic interaction between CMV and potyviruses in cucurbits exhibited different features from that documented in tobacco, indicating there are differences in the mechanisms of potyvirus synergistic phenomena.


Author(s):  
Ivana Stanković ◽  
Ana Vučurović ◽  
Katarina Zečević ◽  
Branka Petrović ◽  
Dušan Nikolić ◽  
...  

2007 ◽  
Vol 21 (1) ◽  
pp. 41-44 ◽  
Author(s):  
Courtney L. Pariera Dinkins ◽  
Sue K. Brumfield ◽  
Robert K. D. Peterson ◽  
William E. Grey ◽  
Sharlene E. Sing

To date, there have been no reports of Dalmatian toadflax serving as a host for cucumber mosaic virus (CMV). Infestations of Dalmatian toadflax may serve as a reservoir of CMV, thereby facilitating aphid transmission of CMV to both agricultural crops and native plants. The goal of this study was to determine whether Dalmatian toadflax is a host for CMV. Dalmatian toadflax seedlings were randomly assigned to two treatments (18 replicates/treatment): no inoculation (control) and inoculation with CMV (Fast New York strain). The Dalmatian toadflax seedlings were inoculated by standard mechanical methods and tested for the presence of CMV using enzyme-linked immunosorbent assay (ELISA). Ten of the 18 CMV-inoculated toadflax plants tested positive for the virus; 6 of the 18 displayed systemic mosaic chlorosis and leaf curling. All control plants tested negative. Transmission electron microscopy obtained from CMV-positive plants confirmed the presence of CMV based on physical properties. To verify CMV infestation, tobacco plants were assigned to the following treatments (six replicates/treatment): no inoculation (control), CMV-negative (control) inoculation, and a CMV-positive inoculation. Plants were inoculated by standard methods. Five of the 6 tobacco plants treated with the CMV-positive inoculum tested positive for CMV using ELISA. All control plants tested negative for the virus.


2000 ◽  
Vol 90 (10) ◽  
pp. 1068-1072 ◽  
Author(s):  
Fernando Escriu ◽  
Keith L. Perry ◽  
Fernando García-Arenal

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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