Future fungus eradication

How far out are we (years) from gene altering, boosting, or inoculating, susceptible roses against funguses?

I can’t even begin to answer your question, but I can suggest that the question is rather unreasonable. IF it turns out to be possible to engineer in some resistance to A fungi, should be honestly expect it to last any length of time? Fungi mutate just like bacteria and viruses. We get different flu shots annually because the flu viruses mutate. We have had to get different COVID vaccines because the bloody viruses mutate. Baby Love, at one time, was one of THE more resistant roses to some strains of black spot, UNTIL a strain (or strains) mutated and “learned” how to break through its resistance. Now, it can collapse under the black spot pressure in some areas. Knock Out is highly resistant to the most strains of black spot of any rose, yet it mildews and rusts with the worst of them. Does it honestly appear it will be possible to engineer any real, lasting “disease resistance”? It doesn’t to me.

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I see it the same way. Nature will always be more powerful in the end and somehow find her way.

There is that, I would add that diseases and plants (as well as people and animals) have all evolved together. “Nature” often uses “diseases” to trigger plants to do what is needed for them to survive. R. Arkansana is very “Arctic hardy”. It’s very healthy in spring with its gorgeous new foliage. Then, it flowers and begins setting hips as it uses up the residual ground water left over from the earlier rains. As the water dries up and the heat continues, it begins to rust, causing it to shed its foliage and begin shutting down so it can continue its “Arctic hardiness”. What gave me this idea? I had a potted Arkansana in full, gorgeous new foliage. I accidentally allowed it to severely dry out and it rusted from the tips of the new growth all the way to the soil. I watered it copiously and it broke out into gorgeous new growth, until it dried out again, when it rusted from the top down. Further copious waterings produced more glorious new foliage. I’d read in British rose books how even resistant roses could be forced to mildew by water stressing them. Really? Yup! I DID it. There are many roses of all types you can literally force to contract fungal “diseases” simply by sufficiently water stressing them. You can easily check if that’s the cause of the disease simply by increasing the water. If it breaks out into new, healthy growth, I’d say it was the water stress. If not, it’s time to either spray or dump it, depending upon your gardening “theology”. Mine is to dump it, but your mileage will vary. Is it honestly realistic to believe we might succeed in engineering resistance to “diseases”? Would we really want to? It would be similar to eliminating pain in our bodies. It would be nice not to hurt, but pain “tells us” something is wrong. Without it, how would we know until it’s too late to fix what’s wrong?

Peter Harris and I used to joke about the futility of breeding for disease resistance. It’s a lot like the three laws of thermodynamics, as I learned them back in p-chem:

  1. You cannot win, you can only break even.
  2. You can only break even at absolute zero
  3. You can never reach absolute zero.

But, of course, you can get close to absolute zero.

Within 100 yards in any direction from my house I can find any number if plants of Rosa multiflora growing wild and showing no sign of disease at all. Scattered among them are, of course, individuals with small degrees of various diseases. The wild population of multiflora having been acclimatized here lives in equilibrium with these diseases (and predators and parasites).

A reasonable breeding strategy for me would have been to introgress refinements from modern roses into those nativized multifloras. Unfortunately for me it was a lesson learned too late to be useful (McGready spent a career trying to civilize spinosissima, for example).

I think CRISPR will soon be used to directly mutate the floral and architectural elements of native and nativized roses (and other plants) on a regional basis. You will have choices of ornamental plants of all kinds that are thus adapted to, and blend harmlessly into, your local ecological environment.

So, I vote yes to both questions.

I am critical of this approach and this development and do not believe that, apart from perhaps short-term gains, it will ultimately completely fulfill the expectations placed in it. It cannot be ruled out that unexpected diseases will emerge. Apart from that: Is such a manipulated living creature, designed under commercial aspects, really a desirable goal? Doesn’t true pleasure in rose breeding and the rose itself ultimately come from the many surprises that the rose gives us with less profound interventions in the genetic material? I am aware that some see this matter very differently. Nevertheless, it was important for me to express my opinion.


Using my usual random approach requiring minimum energy input, l try the kinetics approach to break the bane of my efforts. Still working on eliminating consistently the cursed activation barrier by flipping the curve upside down for germination - fungal not really an issue in my garden of cold eden.

Having spent a lot of time lately in high summer in a temperate climate and seen the so- called ultra moderns laid to foliage waste in display garden … decided what a CoS the adverts are … mind u the ogr’s near/ species laughing for the most part to the bank.

For many of us, yes. However, there always has been, and probably always will be a market for reduced maintenance, disease resistance, increased bloom size and frequency, unique colors, etc, etc. Genetic manipulation promises great and rapid advances in all these areas. Absent government regulation (which I am not in favor of), one can almost predict the death of traditional rose breeding within a few generations.

I was thinking of the old susceptible hybrid teas. I read somewhere in my rose reading a person claimed the hybrid tea was the end of roses because the scrambling of hybridization had at last weakened the rose to near unredeemable disease disasters. A gorgeous flower but a weak and alien plant.
I was I guess sighing of a way to rescue the early hybrid teas by some method like is done with rose stock that is indexed mosaic free. And wondering if AI or something current might find a novel approach, based on the massive volume of studies on roses and fungi.

Maybe 15 years or so ago when I was researching my article on the foundation species of modern roses someone offered me a plant of Soeur Therese.

This was as close as I ever came to having Soleil D’or, the triumph of Joseph Pernet-Ducher being the first technicolor hybrid tea. Soeur Therese comes with a double dose of Soleil D’or and it shows. The petals are delicate with waves of cherry like R. chinensis spontanea but the vibrancy of the background yellow made me wonder if it the pigments were fluorescent.

It proved to be as fragile as it was breathtaking. No amount of life support was enough. I wasted what little pollen it provided on Sericea.

If anyone is looking for a genetic engineering project I highly recommend inoculating the Pernetianas, if there are still any out there to be found.

I read somewhere in my rose reading a person claimed the hybrid tea was the end of roses because the scrambling of hybridization had at last weakened the rose to near unredeemable disease disasters. A gorgeous flower but a weak and alien plant.

Thankfully, there are MANY Pernetianas still around, including Soeur Therese. The plant is sturdy in the more arid parts of California but, as to be expected, the flowers last about half an hour. The “class” has been a passion of mine for many years.


Someone got to the AI punchline before me. Woohoo!

To me, both philosophies (to meddle or not to meddle using advanced technology) have their merits, but maybe it would help if we step back for a moment and think about some plants that we may grow and enjoy that do not generally suffer from major disease problems. Let’s look at (for instance, maybe not best choice) Abelia as a possible example. Here, at least for now (and I assume that it may be the same in many other parts of the world), there are no major disease or pest threats to its appearance and performance as a landscape plant. It is generally tough, dependable, always looks healthy, etc. Present-day plant breeders can freely concentrate on leveraging the available genetic diversity to improve its floral appearance, fragrance, bloom season, leaf retention/fall color, depending on goals, cold hardiness, etc. without worrying about disease as a serious obstacle. Of course, there isn’t nearly the diversity of flowers in that genus as there is in Rosa. Wouldn’t it be nice to be able to do the same with roses, though?–to be able to concentrate our spontaneous, creative breeding efforts on the many more preference-based problems that we are trying to solve without worrying about disease? Do we really need roses to be diseased in order to appreciate them sufficiently, and to continue to improve them through conventional breeding and other means? What does that really mean, and what does that say about us? Of course, it might be helpful to set some reasonable limits on the kinds of problems that we should be leveraging highly advanced technologies to solve, at least at first.

Now for the AI part. It might be tempting to think that we will always attack the problem of diseases with the same impaired mindset that has dogged us so far, where a chance discovery of some single gene (or similarly limited) resistance is hailed as a major advance, and then takes decades of work to combine with other sources of resistance. However, if we could instead make free use of techniques like CRISPR, or even more advanced methods, with the full knowledge that limited numbers of genetic changes will be easily overcome by evolving disease organisms, we should then also be able to make as many genome edits as needed to anticipate and head off or respond quickly to any attempts at co-evolution by those disease organisms. The sustainability of such an approach would not need to be an issue, either: artificial intelligence could be leveraged to design solutions to emerging threats, and maybe even anticipate problems. It should be theoretically possible to design and test genes, whole organisms, and maybe even model entire ecosystems in an entirely virtual environment, using enough computing power. And then, of course, we contemplate the idea/theory that our entire universe is actually just an extremely advanced computer simulation.


One might even say an “intelligent design”.

Or “an imperfect, highly evolved system”.

Touché :slightly_smiling_face:
But I still find it comforting to remain in the Joyce Kilmer camp.

All good things come down to $$ as has been said by a sharp politician in a different context. Making a rose resistant to each biotype of blackspot for instance, will take a bunch of changes (maybe 5-10). then we either have to repeat the process for each rose CV, or do a series of crosses to introgress these trailts into our favorites such as SoeurTherese. That is about 3 generations, perhaps a little more, if we want to keep the traditional behaviors and patterns of growth fairly intact. Virus indexing is simpler, but still costly.

I have managed to get a few roses that are resistant to local diseases by straight selection. Each one is different enough from what’s on the market that it could compete if pesticides were banned. But that won’t happen soon.

Dr. Thomas Debener and his team demonstrated a specific black spot resistance gene could be transferred via recombinant technology and confer its resistance in a susceptible cultivar. He has worked with Rdr1 for a long time now. His work is pioneering leading to the first Rdr gene to be described (Rosa disease resistance). The region on the chromosome where the gene is has a lot of genes (it seems in tandem with the gene duplicated and over time different copies diverging some) and it is difficult to know which is the active copy conferring the resistance. To test which, they took candidate genes in the region and cut it out and put it in the fragrant beautiful old susceptible cultivar ‘Pariser Charme’ and found which is the one. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6638031/pdf/MPP-19-1104.pdf

This was a lot of work… We are coming up with just DNA markers in the general region of the Rdr genes we are studying to have a quick DNA test with a marker tightly linked to the gene. When you find the marker, one is highly likely to have the gene and resistance too. With recombination of the region over generations, the marker may segregate from the gene… We don’t have the money or tools to dig down to the wonderful level Debener did for Rdr1. Hopefully things will be cheaper and transformation of roses easier to find the actual other actual Rdr genes and accumulate them in our favorite roses. Maybe if the active genes are similar enough to current sequences in some roses CRISPR could help edit those genes and make them functional in the way we hope.

I’d love a black spot, powdery mildew, and RRD resistant version of Double Delight :0).

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Who wouldn’t? LOL! Once all of that has been accomplished, crown gall should be the next issue to tackle!

David, since Prof. Dr. Debener has isolated and cloned muRdr1A gene, the active Rdr1 gene, couldn’t the sequences from that gene serve as markers for the gene?

We are coming up with just DNA markers in the general region of the Rdr genes we are studying to have a quick DNA test with a marker tightly linked to the gene.

Hi Don, yes :slight_smile: Rdr1 is in very good shape now. Dr. Debener had a marker before and now can be even more specific in the gene. For the other Rdr genes we are just at the point of being in the neighborhood of these genes with finding markers that segregate with the resistance. From what I last heard from Debener, a German company is about to release some roses with Rdr1 whose parents they received from him years back for them to work with. Ag Canada may have a rose cultivar with Rdr1 (‘Aurora Borealis’). Debener shared some early selections for a field study in Morden containing Rdr1 and they were used in breeding. A seedling in the program out of Debener’s rose (RSM60) was published on recently by Vineland as having Rdr1 and it is the maternal parent of ‘Aurora Borealis’. Hopefully AB has Rdr1 and it becomes more widely available for sale in the US and the other German roses too. They used RSM 60 and seedlings to study winter hardiness inheritance as well as black spot resistance. Here’s a link to the winter hardiness study. https://journals.ashs.org/jashs/view/journals/jashs/147/4/article-p216.xml

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