Rosa multiflora self-compatibility

Can anyone here share knowledge on how self-compatible Rosa multiflora might be?

I have about 20 plants of R. multiflora and we notice that there are hundreds of hips on the plants each year that are selfs.

We have both white and pink Multiflora and they are thornless.

Hi Meg. Thank you…can you comment on what sort of germination rates these seeds give you (if you sow them)?

There was a study done in

Plant Breeding, Volume 122 pg.285-287 2003

done by T. Debener, A. Dohm, and L. Mattiesch

called Use of diploid self incompatible rose genotypes as a tool for gene flow analyses in roses

The study found that even when they used a hybrid multiflora that the seeds from the hips had a distinct male parent and was not self pollinated. The study also showed that roses as far away as 273 yards away are able to pollinate other roses.

So I do not think it is very likely to get seed that is selfed from R. multiflora. I think the seed on this evidence will almost always be crossed by bees.

I wouldn’t agree with this conclusion. I have one clone of multiflora and several plants of it. These plants flower before all my other roses and I get loads of OP hips. I have grown hundreds of seedlings from them and could not say that any were anything other than selfs based on phenotypic characteristics. The seeds germinate after only 6 weeks in teh fridge and you get near 100% germination. The only other rose that flowers at the same time here is ‘Golden Chersonese’ and none have shown any ecae/xanthina influence. The sheer number of OP hips I get also suggest that they are selfs. I get 1000’s of OP hips from 2 plants and my ‘Golden Chersonese’ is just one small plant that is not in full flower production yet. My Multiflora plants are thornless and every seedling I’ve ever raised has also been thornless. The Multiflora flower is a small single fragrant white. Each seedling has had identical small fragrant single white flowers. The leaves and growth habbit are identical. It’s still very cold here when the Muoltiflora’s flower too… not many bees or other insects about at that time of year… not for a month or two yet. It’s winter here now (for a few more weeks anyway)… I haven’t seen a bee for 3 months. The final conlusive bit of evidence, which is the clincher for me, is that last year I pollinated a few multiflora buds from a cluster with buds of different ages. Some were ready to emasculate and pollinate whilst the others were still quite green. I pollinated them and put a small draw string bag over the whole lot. I had intedned to return to pollinate the others too but when they took longer than a week to open I decided not to do them because my pollen had ‘expired’. I left the bag on until the risk of cross pollination had passed and then continued to leave it there waiting until the other buds had matured… they still formed hips even though I didn’t pollinate them and they had died by the time I removed the bag.

Adam, in the article you quoted, did the researches utilise R. multiflora the species as such?

Actually, my local rose grower has told me that some of his OP multiflora seedlings show definite variation in appearance, enough variation for him to be able to select the ones he likes to use as “rootstock donors”.

Mine don’t… only had one variant… it was a tiny one. The others could have been done on a photocopier.

Part of the reason I am asking this question about how self compatible R. multiflora is, is that I have been getting germination rates of consistently less than 10% from one local R. multiflora plant. Each season there are likely thousands of hips on the plant, but the germination I get is always below the 10% mark…It is also true that in one particular sampling of this seed, grubs had been found residing in the seeds.

I also question how accurately one can separate self from F1 hybrid multiflora, just on the look of the seedling.

To make sure I wasn’t messing up with the germination methods, I also opened up around 50 such fresh seeds to check on emrbyo numbers, and found similarly low numbers of normal plump embryos. Craaaaaazy stuff, I say!

Did you try those seed I sent you? They are from these Multiflora plants. You should try them if you haven’t to see just how uniform they are. Whenever I do deliberate crosses with them I always get very poor germination… I get seed but very few germinants and low seed counts, especially with tetraploid pollen.

To be honest, I am very surprised that there is no concensus in thsi thread about the self compatibility of this very common species?!

Did you try those seed I sent you?<<<<<<<

Yes of course, that was over one year ago!

At that time last year, I was very interested in getting my embryo extraction “strike rates” up, and used those tiny seeds to practice ultra-difficult extractions (knowing they would be one of the more difficult candidates to practice on). It was a challenge all right…I probably destroyed half of the good embryos trying that. I ended up with something in the order of 12 seedlings in the end.

Sooooo… any other experiences would be most welcome on this topic of R. multiflora self-compatibility. I am confused at this point to be sure!

Unfortunately the ability for R. multiflora to propagate itself from bird droppings is what is making this rose the

“White Menace”. RRD is rampant among natural plantings of this variety that is classed as a noxious weed in many locations in the US.

I have never tried to germanate any of the hundreds of seeds my plants produce since the only reason we grow them is for rootstock for any RHA member who requested budwood.

I cannot speak of multiflora self-incompatibility nor scientific studies as I do not.

Generally self-incompatibility is not absolute, it weakens either at end of pollinating window or at end of flowering permiting auto fecondation as a last rescue when no compatible pollen is available.

Often times one could consider that there is a preference for foreign compatible pollen rather than absolute self-incompatibility.

The later possibility is quite usefull as it allows one (or bee) a high degree of success cross-pollinating without emasculating. And I know it works with many rose species and vars.

Hi Meg. Yeah that’s interesting, thanks for the extra information!

Hi Pierre. Yes I have read many times that some diploid roses tend to show a degree of self incompatibility. So I was wondering if this is true also for R. multiflora, and to what degree it was true.

What Adam has presented further up seems to support this possibility, but I have not read that article to really comment much more about it.

I have only read the abstract of the paper above. But from the abstract it seems that it studied only a hybrid multiflora. But usually hybrids have more compatibility in general. How they determined crosses in the study was doing genetic test looking for markers and mapping out the gene flow. I believe there are other studies out there on this issue using multiflora but I can not seem to find them on my computer at the moment. But I would also have to say that there is probably huge differences in the species itself some may be self compatable others may have mechanisms to prevent selfs and others may make seed that for one reason or the other does not make it to mature plants. Roses tend to out cross with each other to an extent that makes them hard to predict also.

Perhaps George you just have a bad seed parent. Or maybe you just need to plant another multiflora with a slightly different genetic makeup to insure cross pollination. Try not to let it get lose many places have a problem with this plant.

Also by the way for seed germination rate I have gotten seed from Paul of multiflora. The first year about 50% germinated the second year I got probably about another 15 to 20% to germinate. I know if Paul does not have more than one multiflora there is still a good chance it could be cross pollinated with another multiflora because it has escaped cultivation in Oregon.

Hi Adam.

Yes, I agree, there likely are a number of environmental as well as local clonal factors at play here. It is probably hard to be sure of much else in this case, no?!

You could also if you lack room graft a single bud onto your multiflora or a different clone of multiflora. They do that with fruit trees. If you try one of these be sure to tell us the results maybe in the newsletter. It would be further evidence for or against self compatibility. You already have some before results.