rose yellow mosaic virus (RoYMV)
last revised April 04, 2016
By Henry Kuska
retired, Associate Professor, Department of Chemistry, University of Akron
Ph.D., Physical Chemistry
"This page gives the information that I have collected from my own literature searches and from others posting on the internet. Please let me know if you feel anything is not clear or is not addressed at all as I am continually updating/modifying it as I get feedback." The bold face was added by me for emphasis (H.Kuska).
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RoYMV is reported (Mollov et al. (2013) http://link.springer.com/article/10.1007/s00705-013-1686-7
to be a member of the family Potyviridae. It has a 33% sequence identity to brome streak mosaic virus and a 30 % to turnip mosaic virus.
They found the virus in the cultivars Ballerina, Buff Beauty, Mozart, Cornelia, Nastarana, Dorthy Perkins, and Sir Thomas Lipton in New York and in June Bride and Captain Harry Stebbings in Minnesota.
Rose Symptoms
The disease is characterized by yellow mosaic, premature leaf senescence, and necrotic stem lesions. Fortunately, pictures of infected leaves were included in a more recent paper (Figure 2): Mollov , D., Lockhart, B. and Zlesak, D.C. SYMPTOMS, TRANSMISSION, AND DETECTION OF FOUR NEW ROSE VIRUSES. Acta Hort. (ISHS) 1064: pages 303-310, (2015)
http://www.actahort.org/books/1064/1064_37.htm
Pictures of infected leaves are also available in the free Ph.D. thesis of Dimitre Mollow, page 45
http://hdl.handle.net/11299/171458
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Lack of temperature dependence of the leaf symptoms
The following from the 2013 paper was also of interest to me:
"The common rose viruses apple mosaic virus (ApMV) (synonym rose mosaic virus [RMV]) and prunus necrotic ringspot virus (PNRSV) usually express symptoms early in the season, and the plants
become asymptomatic later, with no possibility to detect these viruses. In contrast, the symptoms caused by RoYMV [19] persists throughout the season, and the virus can be detected. One possible explanation could be the suppression of posttranscriptional gene silencing [37], which is reported to be manifested by the P1 [33, 40]
or HC-Pro [4, 30] peptides from members of the family Potyviridae."
H.Kuska comments:
"posttranscriptional gene silencing" is describing the plants ability to fight viruses by producing RNA interference (RNAi). See: ( http://en.wikipedia.org/wiki/RNA_interference ).
AND
RNA interference is normally effective at higher temperatures but much less effective at lower temperatures. Some viruses have developed the ability to suppress RNA interference. These virus will not show a temperature dependence to their infection ability cycle.
Is there natural spread of RoYMV?
The 2013 paper states the following:
" Potyviruses are known to be aphid transmitted (9), and this transmission is mediated by the conserved HC-Pro motifs. Instead, a putative C-2x-C eriophyid mite transmission motif (39) if found at amino acid residues 48-51 at the N-terminus of the protein, suggesting that this virus may possibly be transmitted by eriophyid mites."
AND
"As mentioned above the RoYMV HC-Pro is missing the aphid-transmission motifs. Similarly, the DAG aphid transmission motif, found at the N-terminus of the CP peptide [20], is missing from the CP of RoYMV. Both HC-Pro and CP mediate aphid transmission of members of the genus Potyvirus. While, as discussed above, the other peptides have similarities to viruses from almost all of the genera of the family Potyviridae, the HC-Pro and the CP amino acid sequences were determined by BLASTP analyses to be similar only to those of members of the genus Potyvirus, which are known to be aphid transmitted [9]. Rose cultivars are clonally propagated [16]. It is possible that RoYMV may have originally been transmitted by aphids and that aphid transmission was lost during an extended period of continuous vegetative propagation."
The 2015 paper states: "Based on viron and genome properties (Mollov et al, 2013b) RoYMY was identified as a new member of the family Potyiridae, many of which are transmitted by arthropod vectors. The potato aphid M. euphorbiae which commonly colonizes roses, did not transmit RoYMV and no other potential vectors were identified. It is possible that spread of RoYMV in roses occurs primarily by cutting propagation and grafting of infected plants, ......... "
H.Kuska comment:
To illustrate that the finding that the aphid, Macrosiphum euphorbiae , did not infect roses does not necessarily mean that all other types aphids could not be a vector for RoYMV, I present the following quote for Strawberry vein banding virus (SVBV):
"The following aphids are cited as vectors: Acyrthosiphon pelargonii, Amphorophora rubi, Aphis idaei, A. rubifolii, Aulacorthum solani, Chaetosiphon fragaefolii, C. jacobi, C. tetrarhodum, C. thomasi, Macrosiphum rosae, Myzus ascalonicus, M. ornatus,, M. persicae .
Of these species, Chaetosiphon spp. are the most efficient vectors in glasshouse experiments, although other genera are probably important vectors when they occur in large numbers and frequently move from plant to plant. Aphids can acquire and transmit the virus in 30-120 min, but persistence in the vector is short, usually less than 8 h (semipersistent type). There are differences in the efficiency of clonal lines of aphids, and evidence that some species will transmit only certain strains of SVBV. Aphis gossypii, A. fabae, Aulacorthum solani and Macrosiphum euphorbiae failed to transmit the virus in a limited number of trials."
H. Kuska comment: It appears unfortunate that the rose investigators selected only one species of aphid for their (RoYMV) aphid transmission tests.
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