Seed grown multiflora can have at least one virus

Background: There have been a lot of attempts to isolate the disease that is Rose Rosette Disease. All have failed, although it has been transfered to and back from Tobacco.

Dr. Rose Gergerich found a multiflora out in the wilds of Arkansas that had RRD and that clearly had not been planted, nor was it a rootstock reversion. She isolated a virus from that seedling multiflora and then infected other multiflora plants with it. The virus WASN’T RRD, but another, as yet undescribed virus. The first report made reference to it as Rose Virus 1, but subsequent recently reported study shows similarities to a (if I recall correctly) a cherry virus that has had some study.

This seed transmitted virus probably isn’t a virus that shows mosaic as a symptom, but is a virus of rose nonetheless.

RMV, rose wilt virus and flower break are the only viruses of roses confirmed in Australia so far.



How did they conclude that the specimen was infected through sexual reproduction and not infected by an insect vector, for example?


There are two papers, and I’ll try to get links to them when I’m at the libery later this week.

You’ve seen the phrase “incidental tourist”, well this was almost the ‘incidental rose virus’ because they started out trying to isolate RRD and ended up finding something else.

I don’t think they considered where the new one came from but I’ll have to check to see if wild cherries were reported from the vicinty of the sick rose.

As to other vectors, there are two things being done.

One is a PhD at Iowa State looking at the total population of insects and acarids on multiflora in Iowa; there are two papers retrievable through Blackwell Synergy. Dr. Obrycki (now at KY) was on the committee and is a co-author; will retrieve those at the library as well. They haven’t started testing the other insects and acarids for their potential as vectors.

Sort of related is the first report of Japanese Beetles as disease vectors of two viruses in beans. The link below is to CRIS, an open site where we can check on what is being done by specific scientists or re specific diseases. The content of Dr. Gergerich’s current research shows the scope of the problems being addressed (as well as the multitude of different plants.) (The new blackberry diseases are also interesting.)



Neither addressed the mode of transmission.

The second paper was published in 2006 and is titled “A new Ilarvirus found in Roses” from Plant Pathology vol 55(4):page 568. In it the disease initially called Rose virus one RsV1 is reassigned to Blackberry Chlorotic Ringspot Virus BCRV in GenBank, because is has an 80% similarity to BCRV which has very recently been reported and studied as it’s doing damage to Blackberry bushes that are a source of income.

Neither of these brief reports considered the spread from blackberry to blackberry.

How did it get from blackberry to a rose ??? with a mutation or possible mutation along the way ??? Or was it vice versa?

(The reference for the first report of RsV1 is 1983 Phytopathology 73: page: 500.)

The recently published paper in Acta Hort 751 Proceedings of the IVth symposium on Rose Researchand Cultivation by Golino, Sim, Cunningham and Rowhani (pages 217-224) bears the simple title “Transmission of Rose Mosaic Viruses”

is a must read. (The viruses they used were Prunus Necrotic and Apple Mosaic)

Their seed tests showed NO transmission by seed.

Their pollen tests showed NO transmiion by pollen

But they found transmission and are looking how it happened and are working with a hypothesis that the problem

happened because of root to root grafting.

I’ve just begun to accumulate the references that Giolino et al. cited. (This is all sort of tied into RRD potential transmission.)

Ann, regarding the Giolino paper. They found no seed and pollen transmission under their experimental conditions. Please note that I added “under their experimental conditions”. I suggest that for temperature sensitive viruses, investigators in a warm/hot climate (when the flowers are blooming and the seeds are forming) should run the transmission experiments in a controlled lower temperature environment such as in an air conditioned greenhouse.

Also, it appears that mechanical trimmers may contribute. In a paper presented a year after the Proceedings of the IV symposium paper, Galino report the following:

See .

for the following brief summary:


Debora Golino (UC-Davis) (with written report) has been documenting the

spread of grapevine leafroll disease in the Napa Valley since 2002. The

disease is spreading but slowly. Rose mosaic disease is associated with

several viruses, but primarily Prunus necrotic ringspot virus and Apple

mosaic virus. After three years, there is no evidence of pollen or seed

transmission of these two viruses. Mechanical transmission with mechanical

trimmers and root grafting appear to be the major routes of virus



But (and this is the kicker) they found RMD transmission even when it couldn’t have happened by the methods they were testing (Pollen, seed, trimmers). And that’s what led to the search for multiple working hypotheses (a geologic term drilled into us from the get go to stop geologists from having a single solution)the possibility of root graft transmission.

They are only able to check Apple Mosaic and Prunus Necrotic because of the availability of ELISA tests. And from some wandering through the search engines today, there are other factors within plants relative to different viruses actions on related cultivars.

In my garden, we had a Tordon caused emergency. Tordon on cut off two and three year old trees (growing from seeds dropped by birds) and then the severe damage appearing on some, but not all adjacent roses. R. laxa, six feet from a Tordon application was affected and lived, but last year was iffy; Betty Bland, closer was unaffected. Dortmund which had the tree growing inside its cane thicket was unaffected.

The difference from cultivars within Rosa mirrors Giolino’s early results with different rootstocks.

Have you seen “Root Grafting: a potential source of of error in apple indexing” from 1965 Plant Disease Reporter 49:39-41 paper they cite? "

Or the Botanical Review 1966 summary “Natural Root Grafting”.

There’s also an earlier paper in Canadian Plant Disease Reporter on Cherry Root grafting as a source of spread of a cherry virus.

I’m going to try to get them at the library in the next visit or two.

As hybridizers, it would be tragic to loose some vigor in vigorous new roses to avoidable diseases.

A picture from a plant propagation book from the 20s shows one big cane of multiflora with twelve different (AND LABELED) buds all budded onto it. Talk about potential sharing of systemic diseases.

Ann Golino et. al. later paper reintroduced the possibility of trimmers.

I do not have a problem with root grafting as a potential cause of virus spread… I do have a problem with using glyphosate as a conclusive test fot root grafting. In hops the glyphosate test was utilized in the 2000 Ph.D. thesis of S.J. Pethybridge on virus spread.

She (Pethybridge) has coauthored a number of papers on this sublect. See:


for her later views of the causes of spread.


I wonder how a conclusive test could be done. Radioactive markers…in sterile planting medium, perhaps. Can’t have any nematodes or other organisms in the soil/soil substitute.

I think we’ll see a lot more on this. To keep the UCDavis collections of rose stocks and grapes clean of problems. they may have to solve the transmission problems, or at least resolve the uncertainty of the sources of the new potential infestations.

This is a very interesting line of thought. Elisa isn’t always that accurate depending on ones threshold for color (background color can vary depending on things inherently in the rose tissue which can be partly cultivar dependant) and how concentrated the virus is. I help Ben Lockart on his rose virus projects. PCR tests are more sensitive. If you know the sequence of the DNA or RNA (depends on the type of virus of course) of a virus and identified selective primers one can determine if the virus is present even at relatively low concentrations in tissue. The presence of an amplified DNA product (through PCR) that is the appropriate length between the primers for your virus would be present or not when the sample is ran out on a gel and DNA fragments are separated according to size. If it is an RNA virus, one converts it to cDNA and go from there. It takes careful DNA or RNA (depending on virus) extraction and more skill and different lab equipment than in a typical Elisa lab, but is very possible in a modern molecular biology laboratory to do this work.

There are many more viruses out there in roses and relatively little has been done to identify more in many decades. There are different types or classes of viruses among what Ben is identifying and documenting. It takes someone with electron microscopy skills (dying art) like Ben to isolate and observe the shape and size of virus particles from tissue. In order to make significant headway it takes someone, also like Ben, that from that can work with different primers common to classes of viruses to see if there are amplifed regions with the primers and sequence those fragments to see what characterized viruses these sequences most resemble. Sometimes it may be a virus already documented in another crop, or a new one with relatively little similarity to what has been characterized in any crop. Transmission studies are important to understand that the symptoms associated with a virus actually are caused by that virus. One way to do so is to take virus-free roses and graft or otherwise innoculate it to get the virus in it. Mode of effective transmission can be documented and is also associated with class of virus and how it moves in the plant as well. One can then watch for symptoms to develop on the virus free rose (hopefully of the same cultivar it was originally found on so you know it should display the symptoms if it actually is the causal agent). One can sequence more of the virus and use PCR and electron microscopy to learn if the virus free rose is now infected with that virus and innoculation was successful, even before symptoms may appear. Symptoms may be transient as it takes particular environmental conditions before it is expressed. At some point a rabbit can be injected with the virus to generate antibodies for Elisa tests. The sensitivitiy of the antibody can be tested to see how specific it is and useful for Elisa. Some of the hosta antibodies and other antibodies used by Agdia and other companies were provided by Ben.

There are many different kinds of viruses. Some can survive in the soil outside of the host for quite a while, while some die soon after being removed from a host. Some are “cryptic” and seed transmitted and do not supposedly reduce much vigor in the host. Some express more severe combinations in the presence of other viruses. There is a lot more to learn. Some are mechanically transmitted, while others are not because they are mainly in the phloem and the phloem plugs up fast when cut and even if some virus got at the cut it typically doesn’t enter then.

I don’t think virus is a hopeless battle. I think eventually we may need to change our mind about “virus-free”. I hate that some nurseries claim this about their roses. They have “virus indexed” roses using Elisa for the few major, characterized viruses out there. I think we’ll eventually accept some viruses as not too harmful and not worry too much about them, while for others there is more concern. Some viruses will be very difficult to impossible to clean up even with heat treatment and meristem culture because of their nature and how they develop and spread. For instance, there is a class of crytic virus that is seed transmitted. It is in every cell, even those in the growing point from the beginning. It would be relatively rare to find a seedling from an infected maternal parent that did not get it. There may be a rose virus that is like that. It takes time and money to make progress with these viruses and Ben is working on it out of the kindness of his heart without funding in his spare time. I should encourage him again to apply for some of the limited ARS research funds.

In the meantime I think, if possible, we should remove plants with obvious signs of infection and try to use good sanitation and pruning practices.