Protoplast fusion of rose with Prunus and Rubus

What a neat idea. I read about the preliminary results of this work in Acta Hort years ago and I think it’s also mentioned in the Encyclopedia of Roses. It’s great the paper is out. This is the title and summary I got on line from the journal it is in (Euphytica). This paper is just on line now and is not in print yet so the final volume and page numbers are not included. It doesn’t seem like it really worked, but perhaps more research can be done with the unusual plants to try to characterize them more and perhaps find some contribution from the non-rose parent or use the technique worked out by this group with rose and other non-rose species.

Cell lines and plants obtained after protoplast fusions of Rosa+Rosa, Rosa+Prunus and Rosa+Rubus

J. Squirrell1, Z. Mandegaran1, K. Yokoya1, A. V. Roberts1 and J. Mottley1

Summary Protoplasts of three Rosa cultivars were fused with each other, with protoplasts of Prunus `Colt’ and with protoplasts of Rubus laciniatus, using polyethylene glycol 4000 as a fusogen. Protoplasts of Prunus were incapable of cell division and those of Rosa and Rubus were disabled by treatments with metabolic inhibitors, either iodoacetate (IOA) or rhodamine 6-G (R6G). Parental protoplasts were then fused in combinations that required complementation for their survival. RAPD analysis of 41 fusion-derived cell lines showed that two lines resulting from fusions of Rosa + Rosa and one from a fusion of Rosa + Prunus, contained some DNA markers from both fusion partners. The others contained markers of only one fusion parent. This showed that after protoplast fusion, the heterokaryons did not develop into cell lines with stable hybrid nuclei. Plants regenerated from cell lines derived from Rosa + Prunus and Rosa + Rubus fusions contained DNA markers of only Rosa and their DNA amounts were no greater than that of the Rosa parent. However, they differed morphologically from the Rosa parent to a remarkable degree, possibly because they inherited undetected genes of Prunus or Rubus, or because they were somaclonal variants of the Rosa parent. Alternative strategies for the production of somatic hybrids are discussed.

Wouldn’t it be neat to use protoplast fusion to combine difficult to cross roses themselves?

In many ways I think conventional rose breeding is going to be a thing of the past in the not distant future.

I studied protoplast fusion years ago. One we are able to replicate the showier flowering aspects of roses on evergreen and deciduous forms of the family rosacaea there will be almost no limit as to what can be created for the garden and almost everything created will be a mule so deadheading will no longer be an issue to impede flowering.

Plant patent law and policing of propagation will become much more important in terms of protecting intellectual and technological investments.


I do not agree: there will be a lot of difficulties such as high investment and large amount of very skilled peoples work needed and others in gene expression such as found at making GM blue roses.

Not to speak of fertility that is aproblem in conventional breeding.

More than twenty years after the first GM conventionnal breeding is actuality with all and every plant. Even those with much more value, GM investment and GM successes.

It is just another tool. Actually quite expensive and with rather low efficience.

Pierre Rutten

I agree this type of experimentation is still very expensive and limited but it is being done and it is getting less expensive and more efficient all the time. Obviously there are people pursuing this type of research. There will be successes.

I worked for a company that had a patent on one of the most popular forms of Rahiolepis in the U.S. It was very profitable until the patent ran out. They also had a patent on an Eriobotrya/Raphiolepis hybrid that was much less successful but it still points out how even without protoplast fusion, patents can make these types of proprietary rosacaea hybrids valuable.

Protoplast fusion breaks all the rules. We can do away with prickles, fruit, many diseases, create true rose trees or true rose groundcovers. All is possible with time.

These types of hybrids will be created. We just haven’t created or discovered the pathway yet.

Pierre, I’m afraid I’m inclined to agree with Robert. There are already a number of firms in the business of creating GM plants for ornamental purposes. In Asia, in particular Japan I believe, there are numerous biotech firms involved in such.

I think I referenced the new blue carnations on a separate thread about mauve roses.

Kind of takes the fun and art of doing it the old-fashioned way. (Sort of like test tube babies in that regard…)

Protoplast fusion is a great tool. It’s been around for awhile. It is more problematic and challenging typically than inserting a single gene into a plant from whatever source especially in really wide crosses. We are hoping that the whole genomes will be able to work together and result in a functional plant. Even in wide species crosses within the same genus even where we can get viable seed set we find vast incongruity and hybrid breakdown because the genomes do not recognize each others cues and signals well for biological pathways and function to occur efficiently to sustain life. In potato colleagues have worked with fusion hybrids of cultivated potato and tuber bearing wild species that are very difficult to cross. These hybrids are promising and hopefully possess enough fertility to be a tool through traditional breeding now to develop cultivars that eventually have acceptable tuber traits and still have the disease resistance and other favorable traits from the species. I’m going to help and do some chromsome counts soon on some of the fusion hybrids. Maybe with ornamentals there is less of a need to go through additional cycles of breeding before something worthwhile is found because of greater leeway in ornamental than agronomic traits.

It can be very difficult to regenerate protoplasts in culture too and takes considerable effort to go through the process as well. As scientists we put genes in here and there, try to force genomes together one way or another (traditional breeding or otherwise)… To a very large extent we don’t know what we are really manipulating and what the results will be. We screen through a lot of deformed and compromized plants before we find ones that possess what we want. That’s part of our fun. We try to generate diversity however we can (traditional breeding generates a lot of diversity already as we know) and then see what we have and what individuals stand out as having greater value.



Apparently the old fashoned way works also, see the link below:

"…and in crossing a rose with a member of the blackberry family, but the bud remained dormant and the seeds did not germinate. Dr. J. H. Nicolas, formerly Research Director for Jackson and Perkins, was more successful as he raised three seedlings of a cross between an apple and a rose. They were similar to the latter in general appearance but showed evidence of apple influence in the bark, foliage, and in the peculiarly colored double apple-like blossoms. The latter, incidentally, were somewhat similar to those produced by Bechtels Crab but not as well formed or as large. The plants were barely

remontant and after blooming they were inactive until fall when a second spurt took place. Further experience with Rose x Apple and Rose x Hawthorn crosses gave similar results and all proved to be sterile."


Further experience with Rose x Apple and Rose x Hawthorn crosses gave similar results and all proved to be sterile."

I would expect this cross to be sterile. I wonder if chromosome doubling would overcome the sterility.

As to the protoplast fusion and to a lesser extent the

‘naturally’ crossed – What’s the aim? OK, re-blooming, rose ‘tree’ would be nice, but a cross species hybrid I think could lead to diseases and pests that are currently isolated to each species to crossover to the other.

Chris Mauchline

SE PA, zone 6

Actually there are as many reasons to try protoplast fusion as there are to do any natural cross and perhaps a few more.

Right now this is a sloppy process wherein, as David Zlesak has said,

"We screen through a lot of deformed and compromized plants before we find ones that possess what we want. That’s part of our fun. We try to generate diversity however we can (traditional breeding generates a lot of diversity already as we know) and then see what we have and what individuals stand out as having greater value. "

As genes are identified, they can be used just to generate the qualities one is looking to transfer to the new hybrid.

Picture any tree or shrub in the family rosacaea with larger rose types blossoms, fragrance, hardiness, repeat flowering and disease resistance and one can begin to imagine the possibilities.

This type of research will be slow in coming because of expense and low priority but one’s imagination is about the only limit.