First R. setigera Results

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philip_la
Posts: 1130
Joined: Thu Dec 15, 2011 10:28 pm

Re: First R. setigera Results

Post: # 73718Post philip_la
Thu Jan 13, 2022 4:22 pm

Males are generally unable to set seed, except in very rare instances, as I understand it.

https://academic.oup.com/biolinnean/art ... 29/2654264
https://experts.umn.edu/en/publications ... gera-michx
Philip F.
Zone 8 / Sunset Zn 30 (Austin, TX -- formerly New Orleans, LA)

david zlesak
Posts: 494
Joined: Tue Nov 26, 2013 12:27 pm

Re: First R. setigera Results

Post: # 73721Post david zlesak
Thu Jan 13, 2022 9:51 pm

Thank you Philip for the links to the articles. Here is the article that is the precursor to our molecular marker article for where in the genome the gender gene is located in R. setigera. http://www.globalsciencebooks.info/Onli ... 60-64o.pdf

The kind of dioecy that R. setigera has is called crytpic dioecy because it is mysterious ('cryptic") due to it looking like both parts are present, but only one gender is functional. Typically pollen from females are pretty empty. Females basically lure in pollen feeding insects and trick them a bit that there is a nutritious reward. It is interesting that both the organs still develop, although have interrupted development part way making one gender nonfunctional.

One male every several years at the MN Landscape Arboretum produces a small crop of small hips with limited seed inside. These seedlings were very helpful for the SNP DNA marker study we did to find markers linked to gender and to test the model that the male allele is dominant. We got the expected 3:1 male to female segregation ratio expected for selfing a male. From the SNP markers I have an idea which seedlings are homozygous dominant males. I made crosses with such males and regular heterozygous males onto 'Serena' to look at segregation of gender and see if the homozygous dominant males for the SNP markers produce 100% male offspring and those heterozygous for the markers produce 1:1 female to males to test the model. It reminds me what people have done to make "super male" asparagus. They took a rare male that made some fruit to find homozygous dominant males to make 100% male seed strains since male asparagus are more productive for spears since they aren't making fruit. I guess with this very unique population of seedlings we can find "super males" for R. setigera. I don't know how practically useful they'd be though.... I have the collection of the R. setigera genotypes used for the molecular analysis in the corner of the yard not wanting to get rid of them because of all the expensive genetic information we have on each genotype in case more can be studied with them and the data leveraged more.

I'm not the best with technology, but was able to generate this link to a video I took last summer of my R. setigera collection when it was in bloom and it may be of interest to folks to see the variation in the plants. I think there is a little bit of inbreeding depression in some of the seedlings likely due to being selfs. https://www.icloud.com/photos/#029GtXqg ... 2f6Pco6OAQ

MidAtlas
Posts: 141
Joined: Mon Jan 28, 2013 8:49 pm

Re: First R. setigera Results

Post: # 73766Post MidAtlas
Sun Jan 16, 2022 1:27 am

David, thanks for making and posting that video! It's fascinating to see the phenotypic diversity generated from that selfing event, and the tetraploid R. setigera is interesting and potentially useful. Was the functionally staminate (or pistillate) nature affected in any way by the chromosome doubling? Was that doubling performed on the same MN Landscape Arboretum clone that was selfed?

I could see a potential unique and practical use for "super male" R. setigera if you were able to then introduce the trait into reblooming hybrids; the lack of seed production might mean more flowering without any need to lower fertility, and a lower invasive risk (although that isn't normally considered to be a problem for garden hybrids), while still potentially providing insects with a valuable pollen reward in the case of single and semi-double varieties. It would be interesting to see whether a chromsome-doubled "super male" could be used to accomplish something like that.

Stefan

david zlesak
Posts: 494
Joined: Tue Nov 26, 2013 12:27 pm

Re: First R. setigera Results

Post: # 73773Post david zlesak
Sun Jan 16, 2022 9:46 pm

Hi Stefan! I'm glad you enjoyed the video. I recorded it last summer and forgot about it. Great question and insights. I treated some seedlings of the female setigera from the MN Landscape Arb and that is where this tetraploid came from. It looks very R. setigera-like and is a likely a cross from one of the two adjacent R. setigera males. R. set. blooms later than the other species around them at the arb, which are typically done by the time the R. setigera flowers. The tetraploid form is male sterile, as well as that prostrate hybrid of it with a shrub rose. I love your idea of lack of hip formation and earlier bloom shedding for strong rebloom if we could generate modern rose hybrids with this male gene from R. setigera. Kevan and others studying R. setigera documented the males have slightly different floral architecture with more blooms over a longer time period. If that could be translated into modern roses, that would sure be nice too. The challenge seems to be for interspecific hybrids (at least in my experience), that the cross only works when R. setigera is the female. Male R. setigera pollen doesn't seem to work on polys or other Synstylae, but the reverse works great. I tried some (female R. set x polys) as females and male R. setigera pollen didn't work on those hybrids... Hopefully there is something we can do to get the male R. setigera allele into modern roses.

MidAtlas
Posts: 141
Joined: Mon Jan 28, 2013 8:49 pm

Re: First R. setigera Results

Post: # 73774Post MidAtlas
Mon Jan 17, 2022 1:11 pm

Thanks so much for the further explanation, David--I had no idea that R. setigera pollen isn't readily accepted by other roses! It would be neat to find out what the underlying mechanisms are; it's hard to imagine that it confers an evolutionary advantage if only the pollen is faithful to the species. I suppose that without resorting to much more high-tech methods to get the male gene into other roses, you would almost have to persuade that male that sometimes bears seed to accept some foreign pollen, and then hope that any hybrids generated have more flexible pollen. It seems like it would take a bit of work either way...

Stefan

Plazbo
Posts: 219
Joined: Tue May 09, 2017 12:18 am

Re: First R. setigera Results

Post: # 73775Post Plazbo
Mon Jan 17, 2022 6:36 pm

david zlesak wrote:
Sun Jan 16, 2022 9:46 pm
Hopefully there is something we can do to get the male R. setigera allele into modern roses.
Possibly something to explore in a sort back crossing (to species...not same cultivar) way

(R. setigera x Modern) x R. setigera


if the seedlings from that still seperate into male/female it may be enough modern for the male seedlings to be more willing.

MidAtlas
Posts: 141
Joined: Mon Jan 28, 2013 8:49 pm

Re: First R. setigera Results

Post: # 73776Post MidAtlas
Mon Jan 17, 2022 7:56 pm

I would have hoped for that to work, too, but David's second to last sentence suggests that approach might also prove fruitless. It's possible that there is no way to get there through conventional breeding, of course.

Karl K
Posts: 1452
Joined: Sat Jun 02, 2012 4:49 pm

Re: First R. setigera Results

Post: # 73780Post Karl K
Tue Jan 18, 2022 1:12 pm

Some details on Horvath's work with Rosa setigera. Maybe someday we'll learn the parentage of his 'Papoose'.

McFarland: Horvath's Roses (1945)
http://bulbnrose.x10.mx/Roses/breeding/ ... h1945.html

Shepherd: The Horvath Climbers (1943)
http://bulbnrose.x10.mx/Roses/breeding/ ... h1943.html

Norton: Story of the Horvath Roses (1939)
http://bulbnrose.x10.mx/Roses/breeding/ ... h1939.html

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