The following is a Ph. D. Thesis abstract. This is the earliest article that I have found concerning the presence of cryptic viruses in roses.

UMI # AAI8614034.

AUTHROR: HANDLEY, MARY KATHRYN.

TITLE: "IDENTIFICATION AND PARTIAL CHARACTERIZATION OF TWO CRYPTIC VIRUSES IN ROSE BY ANALYSIS OF DOUBLE-STRANDED RNA CONTENT"

YEAR 1986.

DESCRIPT 98 p. DEGREE NOTE Thesis (PH.D.)--UNIVERSITY OF CALIFORNIA, DAVIS, 1986. SCHOOL CODE School code: 0029.

SUBJECT Agriculture, Plant Pathology. SUBJ CODE 0480. DEGREE NAME PH.D.

"ABSTRACT Two novel patterns of double-stranded RNA (dsRNA) species, termed pattern A and pattern B, were isolated from apparently healthy roses. Pattern A had 3 dsRNAs, with molecular weights of 1.2, 1.1, and 1.05 megadaltons. This pattern was present in 17% of the 160 rose cultivars tested. Pattern B had 2 dsRNAs, with molecular weights of 1.35 and 1.3 megadaltons, and was present in 2 of the 160 rose cultivars tested. These dsRNAs were not transmitted by graft or mechanical inoculations.

Pattern A was transmitted very efficiently through ovules (100%) and pollen (76%). The properties of these dsRNAs resemble those of the plant cryptic viruses, which have dsRNA genomes contained in 30 nm icosahedral virus flower petals were used as starting material for virus particle purification, pattern A dsRNAs were found in higher concentration in high speed pellet (HSP) fractions than in high speed supernatant fractions. During the summer, no dsRNAs could be found in high speed pellets. Particles approximately 30 nm in diameter were found in HSP from pattern A carriers and healthy plants. This evidence indicated that pattern A dsRNAs may be the genomic RNAs of a cryptic virus; however, much of the dsRNA was not encapsidated, particularly in summer. Rose spring dwarf (RSD) and rose leaf curl (RLC), two virus-like diseases of rose which have unknown causal agents, were not associated with any unique dsRNAs. Pattern A dsRNAs and RSD persisted through thermotherapy. One Rosa multiflora cv. Burr plant which was free of pattern A dsRNAs was produced by shoot-tip culturing. This may be a useful way to generate healthy plant material to investigate the effects of cryptic viruses on their hosts."

NOTE Source: Dissertation Abstracts

International, Volume: 47-04, Section: B, page: 1359.

UNIVERSITY OF CALIFORNIA, DAVIS.

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In 1990 a reviewed scientific paper "Double-stranded RNA associated with the rose rosette disease of multiflora rose" was published by R. DI, H. Hill, and A. H. Epstein.

http://www.apsnet.org/publications/plantdisease/backissues/Documents/1990Abstracts/PD_74_56.htm

However, the authors failed to identify the sources as coming from cryptic viruses.

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A 2008 reviewed published paper from the University of California, Davis titled: "Complete nucleotide sequences and genome characterization of a novel double-stranded RNA virus infecting Rosa multiflora" was published by Nida´ M. Salem Æ Deborah A. Golino Æ Bryce W. Falk Æ Adib Rowhani. They were able to determine that the virus was a cryptic virus.

"http://link.springer.com/article/10.1007/s00705-007-0008-3

In the body of the paper are the following points:

page 460, in the Discussion section - "The origin and agronomic significance of cryptic viruses are still open questions. The natural vectors of these viruses are unknown. They generally appear to have no impact upon host fitness. Their agronomic significance may be found to lie in their potentiation of the symptoms of other viruses with which they co-infect plants. However, although plants expressing rose spring dwarf symptoms are usually found to contain both RMCV and RSDaV lutervirus (here a reference to an in-press paper is given), we have shown that rose spring dwarf symptoms are expressed in RSDaV-infected hosts that do not contain RMCV."

They they go on to discuss the possibility that fungi could be the source of the spread of the virus.

page 455, in the Introduction section - "Cryptoviruses have no known natural vectors. They are transmitted between plant hosts by the ovule and by pollen to the seed embryo, but there is no graft-transmission and apparently no cell-to-cell transport."......"they expand their coverage of their host along with the host's cell devision. The only known mode of transmission is by seed. The highest levels of seed transmission (100%) are obtained when both parents are infected (then a reference is given)."

page 460, in the Discussion section - "These dsRNAs persisted in rose through thermo treatment (then a reference to the Handley theses is given)."

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At about the same time (2008) another paper titled: " Molecular characterization and detection of a tripartite cryptic virus from rose" was published by S. Sabanadzovic and N. Abou Ghanem-Sabanadzovic .

http://www.sipav.org/main/jpp/index.php/jpp/article/view/664

The complete paper includes a "Note added in proofs"

"The research work had long been completed and the manuscript submitted for publication when an article by Salem et al. entitled "Complete nucleotide sequences and genome characterization of a novel double stranded RNA virus infecting Rosa multiflora” became available online (Archives of Virology, DOI-10.1007/s00705-007-0008-3) describing, under the name Rosa multiflora cryptic virus, a virus seemingly identical to RCV-1"

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In 2008 yet another paper reported about the same virus: Title: "First Report of Rosa multiflora cryptic virus in Rosa multiflora in the Eastern United States" by R. R.Martin, and I. E. Tzanetakis.

http://apsjournals.apsnet.org/doi/abs/10.1094/PDIS-92-12-1706B

In it the authors state: " The presence of RMCV has been verified in both symptomless and plants infected with two severe diseases of rose, thus, the virus could play a role in the phenotype of these diseases as part of a virus complex. To our knowledge, this is the first report of RMCV in the eastern United States, which is closley related to RMCV from California (2). In the review process of this note, it was brought to our attention that a similar virus named Rose cryptic virus 1 was being investigated in Mississippi (Genbank Accession Nos. EU413666–68), supporting the statement that this virus is probably widespread in Rosa germplasm."

H.Kuska comment: concerning the statement: "this virus is probably widespread in Rosa germplasm." The following 3 papers support this statement.

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Paper 1 of 3 supporting the widespread statement.

In a 2013 reviewed published scientific paper from New Zealand titled: "A survey of viruses infecting Rosa spp. in New Zealand" by E. J. M. Milleza, L. I. Ward, C. Delmiglio, J. Z. Tang, S. Veerakone, and Z. Perez-Egusquiza the following was found: "The samples were tested by RT-PCR for 17 viruses known to infect roses. Of the 89 samples tested, 48 % were infected with Rose cryptic virus-1, 22 % with Prunus necrotic ringspot virus, 20 % with Rose spring dwarf-associated virus, 10 % with Rose yellow vein virus, 2 % with Arabis mosaic virus and 35 % of the samples tested negative.

http://link.springer.com/article/10.1007/s13313-012-0191-x

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Paper 2 of 3 supporting the wisespread statement.

Title: "First Report of Rose Cryptic Virus 1 in Rosa Plants in Canada" by Dr. Delano James, Mr. James Phelan, Ms. Aniko Varga, Dr. Michael Rott, and Dr. Jean A. Bérubé.

" RCV-1 was detected in dsRNA extracts from locally purchased Rosa cvs. ‘Goldener Olymp’ and ‘What a Peach’"

http://apsjournals.apsnet.org/doi/abs/10.1094/PDIS-09-14-0921-PDN

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Paper 3 of 3 supporting the widespread statement.

The following was published in 2019:

Title: " High throughput sequencing and RT-qPCR assay reveal the presence of rose cryptic virus-1 in the United Kingdom"

"A sample with symptoms similar to those caused by rose rosette virus was positive for RoCV1; further studies will be undertaken to investigate if those symptoms were due to mixed infections with other, as yet undescribed viruses. We also found roses with symptoms of rose mosaic disease which were infected with RoCV1, where ELISA analysis indicated that they were co-infected with ArMV, SLRSV or all three viruses. It is unknown whether the symptoms caused by ArMV or SLRSV were impacted by co-infection with RoCV1, although we found samples with mosaic symptoms which were not infected with RoCV1. Cryptoviruses are not thought to cause direct economic losses in their plant host, although it is not clear what impact they have in mixed infections. "

https://link.springer.com/article/10.10 ... 19-00307-5

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H.Kuska comment: The articles indicate that often the cryptic virus is found along with another virus. My concern is whether the presence of the cryptic virus makes it "easier" for the second virus to overcome the roses' natural immune system.

This is a quote from research titled:

"Fate of artificial microRNA-mediated resistance to plant viruses in mixed infections"

"However, when the plants were pre-infected with these viruses, TuMV was able to coinfect 12-4 plants pre infected with TRV, CaMV, and, particularly, with CMV. So, pre infection by another virus jeopardizes the amiRNA-mediated resistance to TuMV."

http://cat.inist.fr/?aModele=afficheN&cpsidt=27579193

(The complete paper is available as a PDF, but you have to sign up.)

http://www.researchgate.net/publication ... fc96d5.pdf

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Is there any evidence to suggest that this occurs with successful rose rosette infections?

Yes, there is: 1) Early on rose rosette infected multiflora rose was found to also be infected by a cryptic virus (H.Kuska comment: which is transferred through the seeds).

http://www.sipav.org/main/jpp/index.php ... ew/664/451

AND

2) Recently rose rosette infected roses were reported to also be infected by Blackberry chlorotic ringspot virus (BCRV). See the following quote: "The case of Blackberry chlorotic ringspot virus (BCRV) is of particular interest because the virus has been found to be an integral part of blackberry yellow vein disease and is widespread in rose plants affected by rose rosette disease." (H.Kuska comment: BCRV is also transferred through seeds.)

http://apsjournals.apsnet.org/doi/abs/1 ... 13-0866-RE

This "possibility" was tested in a very recent (2014) rose rosette research paper:

Title: "First Report of Rose rosette virus Associated with Rose Rosette Disease Infecting Knockout Roses in Florida"

by B. Babu, H. Dankers and E. Newberry, C. Baker and T. Schubert, G. Knox and M. Paret.

"The samples were also tested using RT-PCR for the presence of Rose cryptic virus (RCV) and Blackberry chlorotic ringspot virus (BCRV) using specific primers (2,3). The samples tested negative for the RCV and BCRV."

http://apsjournals.apsnet.org/doi/abs/10.1094/PDIS-05-14-0501-PDN

Thus, in this case co infection was not necessary. But this paper does not answer the question of whether the co infection made the immune system less effective.

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Here is a general review:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2880111/

"The most well studied of the plant persistent viruses are those previously called cryptic viruses (Boccardo et al. 1987). These are now classified as members of the Partitiviridae. "

" In plants, they appear to persist indefinitely. For example, years of continuous tissue culture, thermotherapy and meristem tip culture were unable to cure plants of partitiviruses (Szegö et al. 2005). "

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My other rose virus sites can be reached from the following index page:

https://sites.google.com/site/rosevirusindexpage/