Marriage

I know the tittle could be ambiguous, but, it has your attention.

Has anyone tried Fimbriata x Zephirine Drouhin either way Fimbriata has no known descendants according to HMF and Zeph has 9. I was asked this question from a Dr(plants, natives) and mentioned I would ask here. I have a young Fimbriata and Zeph, not sure if they would work.

I had Fimbriata for many years. Nothing to show for it. Unfortunately, I did not keep a record of crosses attempted. However, I often used mixed pollen on stuborn mothers.

I also had Fimbriata years ago before I was doing any serious hybridizing. I tried but failed to get any hips from it and I don’t remember trying it as a pollen parent. Lovely flowers though.

Joseph alot of Rugosa hybrids are sterile in pollen and seed carrying ability.

This bit below is from my Dr friend, is this how it works.

.anyway triploid x triploid should give 25% diploid, 50% triploid and 25% tetraploid offspring …but apparently (have been doing some reading) you get a deadlock or a ‘rapid return to an even polyploid level’ but success also depends on the types of chromosomes at play

Not quite :wink:

It depends whether it is making haploid or diploid (or both… and therefore in what proportions), gametes and this varies from variety to variety.

I agree. The 25% 50% 25% of ploidy levels is too simplistic. If there was random assortment and even numbers of fertile 1x and 2x pollen this simple algebra formula should work. Some of the gametes that are aneuploid (plus or minus a chromosome) may lose an extra chromosome, etc. and that is just one of multiple reasons why viable 1x and 2x pollen may not be at the same frequency. There are also 3x gametes and in some triploids pollen this is what it seems is most produced. The size expected for 3x tends to be the size range that has the most well staining grains (if I remember right I think Tangerine Jewel was one example). In addition, in the literature for potatoes and maybe roses if we read between the lines in some articles that with different ploidy levels in pollen being applied, how thick we apply it has an influence. The 2x pollen seems to have a greater competitive advantage than 1x pollen. If we have competition due to a heavy application, we can expect the gametes participating in fertilization being skewed to some degree towards those with a higher ploidy level.

Has there been any research as to why 2x pollen would have an advantage?

The idea proposed is that there is opportunity for dominance. If there is just one set of chromosomes there may be a compromised allele of a gene that makes it less competitive in pollen tube growth, etc. There is an estimate that ~40% of genes in the plant is expressed in the gamete, so there is a lot going on in the gametes than what it may seem. If there are two sets of chromosomes, there is a chance with two copies of each gene, that there is one allele that is functional and can mask the nonfunctional allele.

To Simon and David Z and others, this is part of the response from my friend, is this how it “might” be ?

i reckon one way might be to self Fimbriata first, (some should work) and try and restore ploidy to an even number in the F1, then move forward with an outcross with Zd… anyway this is just speculation.

As I have said this way beyond me, but I find it interesting.

If you self ‘Fimbriata’ it may restore an even ploidy towards either the diploid end or the tetraploid end. It may also just make more triploids. You won’t actually know unless you have them tested because it’s not that clear cut. Personally, I would not be selfing it with that goal in mind because you aren’t guaranteed of success and rugosa hybrids can take years to flower to move forward with. I’d be working out what cross you want to do with it and just doing it. I recently chucked out a ‘Scabrosa’ x ‘Black Jade’ seedling because at six years old I still had not seen a flower and it was looking like one of the rugosa hybrids that would NEVER flower. 'Rugosa ‘Alba’ x ‘Papageno’ was set to flower in its second year till a wallaby ate its buds.

Triploids can be very useful in breeding because they can go either way… to diploid, triploid and tetraploid (with tetraploid or triploid parents). I.e. theoretically (not actually…) triploid x diploid would give you both diploids and triploids, depending which way, and to what extent, the gametes go in the triploid. Triploid x triploid could give you anything from diploid to tetraploid, and triploid x tetraploid could result in triploids or tetraploids (for the same reasons as trip. x dip.). In reality this is also a simplistic view and really the roses can (and do) things that you would not expect (see: Mr Moore’s ‘Muriel’).

Given that ‘Zeph. D.’ is also a triploid a cross with it could go either way or not change at all.

David, can I ask… what’s the goal you have in mind with this cross? ‘Fimbriata’ is a rugosa/Noisette hybrid. It grows taller, and more climber-like than do other rugosa due to having ‘Mme. Alfred Carrière’ as its Dad. Adding a rose like ‘Zeph. D’ to the mix makes it highly likely you will make more large climbers… which is fine if that’s what you want. The other thing I have found is that putting rugosa with any moderns creates a plethora of mildew issues… I would not be putting something with mildew issues already into the mix. Depending on what your goals are… if you were after shrubs that are good for Australian conditions you might be able to take advantage of the Noisette blood flowing through its veins by combining it with Teas or China roses or even some of the Polynatha/China roses like ‘Perle d’Or’ or ‘Cecile Bruner’ (bush version). I’d LOVE to combine ‘Fimbriata’ with ‘Blush Noisette’ because the Noisette in it might stand more of a chance of working with it, BN is more of a shrub than most Noisettes and I think if some of the frilly nature can be put in BN-style clusters of flowers it would be beautiful. Or… I can send you one of my ‘Trier’ x ‘Monsieur Tillier’ seedlings to try with it too that might work in the same way.

[quote=davidzlesak]

The idea proposed is that there is opportunity for dominance. If there is just one set of chromosomes there may be a compromised allele of a gene that makes it less competitive in pollen tube growth, etc. There is an estimate that ~40% of genes in the plant is expressed in the gamete, so there is a lot going on in the gametes than what it may seem. If there are two sets of chromosomes, there is a chance with two copies of each gene, that there is one allele that is functional and can mask the nonfunctional allele.[/quote]

I can see how this would skew things in favour of the x2 pollen, but cant see that the affect would be enhanced by heavy application of the pollen, or reduced by lighter application. Assuming that the percentages of x1, x2, and x3 gametes are fairly uniform throughout pollen of a given triploid, I would think the ratios should be the same regardless of the quantity of pollen applied, unless the x2 pollen has an additional advantage that allows it to out-compete the x1 pollen.

Could having two working copies of the gene increase the speed of pollen tube growth?

Perhaps we should look at diploid and teraploid pollen to see if is any difference in the speed of tube growth.

This may simplify the discussion on Marriage. From my personal experience I have never found a hip on Fimbriata nor was I ever able to set a hip on Fimbriata. Pollen was nonexistent or nonfunctional.