Second article of self sterility - sob

I tried posting this earlier, but the size limitations would not permit it to go through. The reason that “sob” is in the title is that this paper states that 2 of the 3 tested species roses are self-fertile. I am writing a paper on virus infection in roses. One of the key points that my “viewpoint” depends on is that species roses are self sterile as reported in the first paper that I posted. Why can’t nature be simple? My only hope is that the two species roses that they report as self fertile actually contain some mixed “blood”. This is why I am asking for input. I am especially interested in R. multiflora. Does anyone have an isolated R. multiflora? Does it set hips. If so, does it set a lot or a few hips; and do you know if the seeds were fertile?

Title: Difference of intra- and interspecific cross-compatibility of fertilization in several genus Rosa.

Authors: Han YounYol and Yu SunNam

Published in: Journal of the Korean Society for Horticultural Science, Volumn 43, pages 326-332, (2002).

Abstract: "For rose breeding work, 5 cultivars of 3 naturally grown Rosa spp. and 68 rose cultivars were examined. The characteristics of flower organ, pollen germination, self-fertilization of parent plants and

crossability were studied. Crosses of wild plants of Rosa spp., R. multiflora and R. wichuraiana were self-fertilized. Although R. rugosa showed pollen germination in the stylar tissue, it failed to reach self-fertilization. Crosses among wild species, 5 combinations of reciprocal

crossing with R. multiflora and R. wichuraiana showed affinity, but 7 combinations of reciprocal crossing with R. rugosa and the other native species showed little affinity and low fertilization. Of the 37 cultivars, 24 including ‘Mount Shasta’ were self-fertilized. However, 13 cultivars including ‘Cannes Festival’ were unable to reach self-fertilization. The rates of pollen germination, the self-fertilization, and the number of seeds per hip were very different among cultivars. The results of reciprocal

crossings among diploid wild species of Rosa spp. and tetraploid rose cultivars when tetraploid cultivars were used as pollen parents, the hip size was bigger and the number of seeds per hip were higher than when diploid wild species were pollen parents. On the other hand,

self-fertilization and crossability of 357 combinations of cultivars were investigated. The rate of fertilization was in the order of Spray type, Climber type and Hybrid Tea. Floribunda type showed the lowest fertilization. When the cultivars with big flower was used as pollen parents, the hip size was big and the number of seeds per hip was numerous."

I have a single plant of R. multiflora. It was the rootstock of a rose that died. It sets a few hips. I haven’t tried to grow the seeds. I’ll check to see whether there are any hips still on it. There are three roses near it, two triploids and a tetraploid.

There are a couple of relatively isolated R multiflora plants near here in two different areas. I’ll try to drive by and see if they set hips. I’m pretty sure I’ve seen hips on the big plant, but last I saw the small plant it had been mowed down. I’ll try to go looking in the next few days. I

As I recall, the multiflora was the first thing to bloom last Spring. I don’t remember whether it overlapped with the neighboring roses.

Joan, no thank you, at this time, concerning your offer of sending the hips. That would make more of a project than I now have time for.

We have a multiflora that is at least 100 ft from our rose gardens and 50 or so feet from our greenhouse. There were no hips on it. There is a minetti (sp) out in that area as well and it doesn’t have hips either.

Thank you John; but as Joan pointed out, there is the complication of birds. Do you remember if there were no hips in the early fall?

Joan, I should of thanked you for your very important observation that I have to consider birds. Thank you very much - I guess some things are better done by committee in spite of all the jokes about the concept.

Henry - No there were no hips this fall. I had been looking at it every now and then to get some cuttings to root and nary a hip.

Wow, thanks John. I would send you my next born child, but at my age …

Roses have a gametophytic self incompatibility system which can be easier to break down than a sporophytic system. If one does things like expose the plant to elevated temperatures (degrades the self incompatibility proteins) or a number of other things like alter pollination time… one can get around it and obtain selfs. I had a diploid rose that normally does not set hips when isolated in the greenhouse. It set a number of hips in the greenhouse after a hot spell. I raised the seedlings and appear to be selfs (thornless like the female parent, a recessive trait and morphologically similar in other ways too).

David

Henry - thanks is enuf! Another child??? Hey, maybe that would be a good name for a new rose.

Well, both of the plants I knew about have been cut down, so that’s no help. Good luck with the article.

Joan

Joan, cut down, oh sure - my foot, you just don’t want me sending you any next born. :<)

Joan, I was so proud of my little humor, that I forgot to say thanks for looking.

Heps on Veilchenblau but not on Bleu Magenta is all I can tell you.

You’re welcome Henry. I supose it wouldn’t be to bad if they were already house trained…

Henry,

I have two plants of R. multiflora, both of which are old, well established plants of considerable age. (Likely date back to 1960’s or older) They are not “isolated” by any means as there are hundreds of roses within 1/4 mile of their location. That being said, I have often watched the bees and other insects busily pollinating these plants in the Spring. I believe it is a reasonable assumption that 95% or more of the pollinations that occur are selfings, and yes…these plants set a staggering number of hips. They are most certainly fertile seeds, because I have collected them and germinated them with the intention of using them as bud stock. Not all of them were used for grafting; one flat of about 25 plants remains, all of which are well rooted now into the ground under the flat. From what I can tell, these seedlings are all R. multiflora. Not all have bloomed, but those that have produced single white blooms just like their parent.

Regards,

Paul

Paul, thank you, are the 2 bushes close to each other?

Henry,

They are about 200 yards apart, with many other shrubs and full sized trees between them.

Paul

Thank you Paul (you realize that your answer disqualifies you for a “next born child”).

I have 3 possible explanations to throw out for discussion.

  1. I have read that in crosses with species roses, the first generation often looks very much like the species - yes, no, maybe?

  2. I have also read that a small amount of eligible pollen will break the barrier for pollen that would normally be incompatable.

  3. Paul Barden is such a good hybridizer that even the telephone pole produces hips.

Any comments?