Breeding strategies

Anonymous · January 18, 2006, 6:00am

Say I want to cross a modern rose with a tetraploid species rose. Apart from what parent to use, there are several combinations of crosses.

If the modern rose is Y and Z and the species a and b which of the following option would you choose?

(I use the species as pollen parent, because that seems to work best, regarding crosses with species made by others in the past).

(Y x a) x (Y x a) - a self of a (modern rose x a species rose)
(Y x a) x Y - a cross of a modern rose with a species rose and this backcrossed to the same modern rose
(Y x a) x (Z x a) - a cross of two (different modern roses x the same species) hybrids
(Y x a) x (Z x b) - a cross of two (different modern rose x different species) hybrids
(Y x (a x b)) x Y - a cross of a (modern rose x a 2-species hybrid) and then backcrossed with the same modern rose

Option 1 and 2 are quite similar, although option 2 would be preferred with respect to the percentage of reblooming seedlings that is higher than with option 1. However, it would immediately dilute species characteristics in the F2 hybrid.

Option 3 has two modern roses and one species rose. Since modern roses are genetically closer together than two species roses, this would not differ much from option 1. I guess. However, if Y and Z are of very different breeding lines (e.g. Y being a landscape shrub and Z a HT) it would give more variation than 1.

Option 4 uses two modern roses and two species. This gives the opportunity to get more species characteristics in a cross, but maybe this cross will be harder, because of differences in genetic composition between the hybrids.

Option 5 would only be logical if the hybrid (a x b) already exists and is fertile. Otherwise (a x b) will be a once bloomer and (Y x (a x b)) also, so that would mean waiting for two generations of once bloomers.

So, my guess is that strategy option 3 and 4 are best, 4 being more difficult but more rewarding than 3. And 3 being more in line with Louis Lens’s advice to take small steps at a time.

This is just my thinking, I have no experience yet with such crosses. What do you think?

Rob

Anonymous · January 18, 2006, 6:00am

Quite interesting as it was so little done in the past. Only notable exception being cold resistance breeding. Introductions ample majority is from two vars with eventually interposed breeder seedlings whose main interest is in good seedling production.

As to which of your crosses is more advisable this is quite difficult to predict.

As you point HTs are genetically quite similar.

However roses are often non mendelian so predict a cross results is only from experience.

Others experience is not so reliable. Even if we can think getting similar results is a possibility we cannot be too much confident as i.e. species are not homogen and denominations sometime questionable.

Just what are you intending to do:

If it is introgressing monogenic dominant species feature then cross 2 is advisable as you will recuperate earlier recurent flowering and lasting flower; two wanted feature rose species are lacking.

If it is introgressing monogenic recessive species feature then cross 1 or 3 are more advisable as you should get a few recessive expression for next step.

Even monogeneticaly controled character expression is more or less environment dependent. Genome environment first, then cytoplasm and ultimately ecological plant surounding. As many features i.e. frost resistance are obviously polygenically controled introgressing this is another story. This could point to crosses you do not list.

To make it short a strategy is a necessity if you want not to just cross a nice rose with another one hoping for good fortune.

Adaptation of said strategy is another necessity. From the results you will get and how you will ponder them, at each step you will have oportunities to consolidate or shift - change your plans. Within (a few?) years you should cope with too much oportunities.

Thats why when beginning I made all your crosses and more. Going further with what I thought more hopefull.

May be I am not so helpfull but it worked like this for me.

Pierre Rutten

Anonymous · January 20, 2006, 6:00am

I have to agree wholeheartedly with Pierre. You can think everything thing out and go with what you think is best, but often times you’ll end up changing strategies mid-stream anyway because of discoveries you make along the way. So, like Pierre, I just tried anything I could and continued with the particular avenues that seemed most productive at the time. You’ll find that (when working with species roses especially) there are some generalities, but MANY more individualities. Often what seems like the most direct way (by reasoning) turns out to be very unproductive (or even impossible); on the other hand, half-hearted attempts (done “just because it was there”) sometimes surprise you with great results.

So, enjoy the thinking and planning but make sure that you “dive in” and just do a lot too. You’ll have tons of fun and learn a lot too.

Anonymous · January 20, 2006, 6:00am

Precisely what Tom said. Don’t lock yourself into rigid plans or you will find yourself very frustrated in the long run.

Paul

Anonymous · January 20, 2006, 6:00am

Rob, I think that you have poised an interesting question. Definitely keep your mind open and flow with the direction that gives you the best results.

Off hand, I like your option 3 the best. For me, when using species roses, it is for the reason to introduce a particular trait from that species into modern roses. I think that strategy 3 may also give you a higher degree of fertility while concentrating the desired species trait, but that is opinion not science!

Jim Sproul

Anonymous · January 22, 2006, 6:00am

Rob,

I should also add that I feel that it is worthwhile when introducing species, to make the cross of Species x Modern and then select some seedlings and cross the siblings with each other in various combinations. In this way you have an opportunity to increase the chance of concentrating the desired species traits and also gain a percentage of remontant offspring. Several other breeders have suggested this to me, and it has been written about in texts as well.

Paul

Anonymous · January 23, 2006, 6:00am

Thank you for your replies!

I will of course do a lot of trial and error in my hybridizing efforts, and more than the thought out strategies mentioned above. But it’s winter now, so what more can you do than waiting for seedlings to grow and germinate, and plan crosses for the future?

Species interest me because they have disease resistance traits that may be stacked to those already present in resistant modern roses (like most of the very recent Kordes hybrids). I’m in zone 7 so hardiness is not much of my concern, and I can’t test for it either.

I’m also interested in species because the Wageningen Botanical Garden is very close to where I work and they have a lot of species growing there. This will be my main source of pollen.

Paul, I will try species x modern rose crosses someday but the plants I ordered will take a few years to become useful as parents. Until then I’ll have to use the pollen from the Botanical Garden. I don’t think I’ll be able to use their plants as seed parents Would love to see the look on the garden keeper’s face when they suddenly have all their roses covered with labels with fancy names!

For this year, I’ll take the first step and that is crossing modern roses x species. Then I’ll see next year whether something actually germinates from those seeds!

Rob

Anonymous · January 23, 2006, 6:00am

I agree with Jim that using species in a breeding program with modern roses should be done with the goal of developing a specific trait in the progeny and nothing else. Unless Rosa wichuraiana is used, forget about developing disease resistance when breeding species with modern roses. Species are resistant to diseases for an obvous reason. If they weren’t, they wouldn’t have been able to evolve and survive in their native habitats. However, when species are mixed with modern roses, generally their disease resistance is not enough to overcome the disease susceptibility of modern roses like Florabundas and Hybrid Teas.

A classic example of a breeding program using species and modern roses and not increasing disease resistance are the Parkland roses of Canada. The species used was Rosa arkansana and the progeny or at least selections introduced are generally disease resistant for the U.S. and Canadian northern Great Plains region. However, when the cultivars are grown in regions where the humidity is higher in the summer they are quite prone to diseases. In this case, Rosa arkansana (a tetraploid) was used with the specific goal to increase cold hardiness, while also having the ability to contribute the repeat bloom characteristic to the progeny. Rosa arkansana is also relatively low growing and thus was an ideal species to develop a bedding type of rose, which was also a goal of the Parkland rose breeding program.

In comparison, the Canadian Explorer Rosa kordesii breeding program has generally produced cultivars more disease resistant than the Parkland cultivars. The difference - there is a good dose of Rosa wichuraiana in the pedigree of these roses (a small percentage of Rosa wichuraiana is also in some of the Parkland cultivars). I realize it may be the combination of Rosa wichuraiana and Rosa rugosa in Rosa kordesii that may be more important than just straight Rosa wichuraiana in the pedigree.

In my opinion, there should be more work done developing species hybrids with Rosa wichuraiana. Then these species hybrids, including amphidiploids developed from ones lacking fertility, could then be used in breeding programs with modern roses. At this point other than using Rosa kordesii, it might be possible to develop disease resistance and at the same time incorporate a specific trait into the progeny.

Anonymous · January 23, 2006, 6:00am

Paul I know you have been preaching using R. Wichuraiana to gain disease resistance but I live in the deep South on the Gulf of Mexico and I am trying to use Darlow’s Enigma to get disease resistance to modern roses and last year I got one mini to cross with Darlow and the offspring is a mini with disease resistance like Darlow so I believe that Darlow can pass disease resistance. I have several hundred seeds from Darlow from several different modern roses(mimi and bush form) and have a few seeds using Darlow as the pollen parent. Some of the seedlings will start to bloom any time now so I am getting excited. I may have to use just minis with Darlow to get this going as they seem to cross with Darlow better. I know Darlow has excellent disease resistance for blackspot just about anywhere but believe I saw somewhere that is might get a little rust or mildew, wouldn’t know as I don’t get much of either here. Would appreciate your thoughts on these strategies. Thanks

Patrick

Anonymous · January 23, 2006, 6:00am

Rob

Like you I think Kordess is way ahead of other breeders at breeding desease free roses. Frost hardy too.

Their roses health appraisal on paper or website are quite consistent “without sprays” even in a different warmer climate.

Much better than others appraisal that should read “with usual spraying” implicit understatment.

This is the result of a long and persistant breeding work.

Look i.e. at Goldmarie and Clare Grammerstorf ancestry.

Paul

I agree. Desease resistance is and will be from crosses with for millenaries nature selected species. We have to be quite cautious evaluating our seedlings eventual resistance as cold wet and warm wet deseases strains and succeptibility are quite different.

As for breeding with wichuraiana: it is not that easy. Even if strong growing its hybrids are more tolerant than resistant.

Like Patrick I think we should explore different pathes. Stepping on others successes.

Pierre Rutten

Anonymous · January 23, 2006, 6:00am

Though most of the respondants have experience to the nth degree beyond mine, my gut would have gone with what Jim said. Then again, hybridizing is one of those knack-things. Ya gotta do a few thousand seedlings before forming one’s own conceited (yet malleable as the next hundred seedlings will likely prove you wrong) opinions.

I haven’t yet crossed a few thousand, but that doesn’t prevent me from opining.

Paul O., while - as I say - you have probably grown a hundred-fold as many seedlings as I, I am a little surprised by your disease-resistance goal assessment as it pertains to species. There are, to my mind, many species hybrids which appear to exhibit extreme resistance obtained from ancestors. Unquestionably, one can breed disease susceptibility into a rose by selecting the wrong species.

Of course, it generally takes generations to get to where you can hang a pretty flower on a descendent…

If I may be allowed to hypothesize on the problems with disease-resistance in species descendants I would speculate that different rose species use different strategies to contend with diseases in their environment. Species, for instance, may adopt a strategy of resistant cuticles, or shed diseased leaves quite freely, or…

(Species from the arid regions of the middle east needn’t sweat the issues of BS or mildew too much, lack much of any strategy, and are likely to have inherent problems. These will be passed on.)

When crossing roses having different strategies, you may weaken any strategy either parent may have had. For example, a rose which rapidly sheds diseased leaves crossed with one with a highly resistant cuticle might yield a rose with a weakened cuticle which retains diseased leaves creating more spores to infect more leaves. As they say about the weakest link in a chain, the more strategies that are compromised by crossing…

Thoughts?

Hypothetical reasons aside, while many species crosses may yield weakened resistance, that is not always the case.

I personally don’t feel I have the time to cull and hybridize multiple generations to get at my goals, so I’m inclined to recommend using another’s F1 species hybrids. Most of the more probable candidates, alas, are not commercially available as they may not be marketable at their current level of development, yet they show promise in further breeding…

Dr. Basye had some interesting species hybrids which, I believe, have been made available. As you are in zn 7, you could look at some of his. I haven’t tried it, but from what another has said, the rose called “Basye’s Legacy” sounds like an intriguing potential parent plant – though I would say it would take a couple generations to hang a pretty flower on the thing…

(Basye’s Legacy: Seed: R. moschata abysinnica

Anonymous · January 23, 2006, 6:00am

I think many of the SE Asian ramblers would be good to add into the mixing pot much like Rosa wich.

Anonymous · January 24, 2006, 6:00am

Philip, my largest cross with Darlow’s Enigma last year was Lynnie which has Basye’s Legacy as one of its parents. I have close to 1,000 seeds of Darlow’s Enigma X Lynnie and hope to get some good disease resistance and maybe some thornlessness, hardiness and even fragrance from this cross. I am determined to use Darlow’s Enigma to get disease resistance and until I see that it is useless I will keep trying. It looks promising so far.

Patrick

Anonymous · January 24, 2006, 6:00am

Lots of interesting points! I’ll add a few, from my experiences with species hybrids and disease resistance…

First let me say that I use no sprays or even fertilizers, and I don’t do a lot of weeding or pruning. So, what I grow, has to tolerate quite a bit of neglect (bordering on abuse ;0). I live in mid-Atlantic North America, where the summers are extremely humid – so disease pressure is pretty high.

Rosa multiflora X rugosa has been very disease resistant for me. I’ve only occasionally seen some minor mildew on the peduncles and receptacles of flower buds.
Rosa rugosa X glauca is very disease resistant also.
Rosa moschata X wichuraiana has general disease resistance somewhere in between its two parents. Also, the seedlings seem to be divided 50:50 for moderate susceptibility to mildew.
Rosa ‘Fragrant Cloud’ X carolina is more resistant than its mother but less than its father. One seedling of this hybrid (from ‘Carefree Sunshine’ pollen) appears to be completely mildew free.
Rosa rugosa X carolina is very disease resistant.
Rosa rugosa X palustris is very disease resistant.
Rosa eglanteria X rugosa was a weak cross and had more susceptibilty to disease than either parent - something like the susceptibilty of Hybrid Teas and Floribundas.
Rosa bracteata X (rugosa X palustris) seedlings vary in their health, but generally show more disease than either parent. Still I would call them VERY healthy by comparison with Hybrid Teas and Floribundas.
Rosa multiflora X ‘Mutabilis’ is very healthy. Probably somewhere in between its parents but closer to multiflora in resistance.
Rosa arvensis X soulieana seems to be just as resistant as either of its parents.

I’m inclined to agree with Mike’s (? jadae ?) opinion that the SE Asian ramblers in general, have a lot to add as far as disease resistance goes. One I haven’t used yet that has shown impressive health for me, is Rosa helenae. I have one growing completely untended. It’s a huge, completely healthy mound so far, in spite of being surrounded by dead and dying multiflora (from Rose Rosette disease).

Anonymous · January 24, 2006, 6:00am

Patrick, in point of fact, it was Kim Rupert (who hybridized Lynnie) who had extolled some of the virtues of Legacy to me which I relayed above. Aside from he and perhaps Ralph Moore, I don’t know of anyone currently using Legacy, but I’ve been curious about it.

Tom, I gather that crossing different species crosses (to get, for instance a four-species cross) can yeild real chimeras, from what I understand, which may have much flexibilty for further breeding. I would be curious as to what your 9 crossed with 5 might yield. It might offer the possibility of remontant resistant offspring, no?

I also agree that roses in the Synstylae, for instance, seem like good prospects. And many first generation crosses do have spectacular blooms. (Setigera seedlings, for instance, can yeild luscious cabbagey blossoms such as those of Long John Silver.) In addition to helenae, and setigera, I’ve wondered about brunonii (La Mortola). Alas, I have no room for such monsters! (and have no experience nor first-hand knowledge of them)

Anonymous · January 25, 2006, 6:00am

Check out the hybrids coming out from India. And theyr epurchasable, too. But like you, I do not have the room =(

Anonymous · January 25, 2006, 6:00am

Philip,

I hadn’t considered crossing 9 and 5. I’ll have to think about that one.

But as far as remontancy goes, when you’re working with species, you never know what you’re gonna get. It’s definitely not a simple matter of dominant(once-blooming) / recessive (repeating). For instance, my F1 multiflora X rugosa, and F1 rugosa X carolina, both produce fall flowers. The first one actually bloomed continuously through the summer of 2005. On the other hand, rugosa X palustris has never repeated, at all; I haven’t even gotten any repeating F2 from it. Another twist, ‘Fragrant Cloud’ X carolina is a once-bloomer, although both of its parents repeat.

So, since it’s so unpredictable, I rely more on other aspects of the hybrids and just let the remontancy genes mix and mingle according to their own devices.

Something that may be of interest to you… Percy Wright felt that mixing too many species all together, too rapidly, was a bad idea. Read the following link for details.

Link: www.bulbnrose.com/Roses/breeding/Wright/Wright_compatible.html

Anonymous · January 25, 2006, 6:00am

Paul, could you explain why you think that only R. wichuraiana is useful for disease resistance? (Does Knockout have R. wichuraiana in its parentage?)

Isn’t R. wichuraiana already widely used? The Flower Carpet series is derived from R. wichuraiana through Immensee and The Fairy. Kordes used this rose also to breed resistant shrub and ground covers. Noack most likely uses it too. Lens also used R. wichuraiana in various combinations.

It seems a path well-traveled. Sure there is much more to be done with R. wichuraiana, but that statement seems valid for other species as well.

Rob

Anonymous · January 25, 2006, 6:00am

Have any of you ever seen Green Snake? What a weird cultivar!

Anonymous · January 25, 2006, 6:00am

I still say that Rosa wichuraiana is unbeatable when using species in a breeding program with modern roses. Its track record for developing disease resistant roses, whether it is the Canadian Rosa kordesii, Kordes Rosa kordesii or Kordes Rosa wichuraiana groundcover speaks for itself. The greatest advance in rose breeding the last century occurred when Wilhelm Kordes developed Rosa kordesii, the amphidiploid of the Rosa wichuraiana/R. rugosa species hybrid.

I note that in a study of blackspot and Cercopora leaf spot of about 30 groundcover rose cultivars and species done by the Brewton Experiment Field, Mobile, Alabama in 1998/1999, “over the two-year test period, the groundcover rose Rosa wichuraiana showed the best resistance to both these diseases, and this rose appears to tolerate hot, droughty conditions.” Interestingly, in this study ‘Bonica’ having Rosa sempervirens in its parentage was not particularly disease resistant. ‘Bonica’, of course, is always promoted as being a very disease resistant cultivar.

Having said the above, I have always maintained it is best to stay away from modern roses in a breeding program. Unless the breeding program can be done on a large scale, it is almost impossible to develop disease resistant progeny. And gardeners and rosarians are increasingly not tolerating disease susceptible roses anymore. Why are we fixated on using modern roses in a breeding program, when there is so much potential to develop unique, tough and disease resistant roses by concentrating on using species and species hybrids?