Over the years I assumed the seedlings with more reddish color early on would make darker colored flowers. I haven’t followed any through to see if that truly is the case or not. Have others tested this? I potted up some reddish and more soft yellow seedlings separately from the same family and hopefully will be able to see if there is a trend.
Nice thought, but not necessarily so. Those reddish foliage/plant parts hint that red tints might show up in blooms, but they don’t HAVE to. Mrs. Dudley Cross, Mme Antoine Mari, Faith Whittlesey are just a few out back with quite reddish foliage and basically white flowers (though some pinks do eventually appear, or are initially there before fading). Of course darker seedlings are possible from them. I have dark pink selfs from Mme. Mari.
Some of those unusually colored seedlings have turned out to be albinos. 
Peter
I have tended to assume the same likelihood, David, particularly when culling through species seedlings, though I don’t have evidence to back that assumption up. Now that you have me thinking about it, with more complex hybrids, my inclination would be to be much less presumptuous. I do tend to think of e.g. yellow blossoms more commonly arising from apple green leaves, and red blooms from foliage/stems with underlying bronze tones, but this is certainly not the rule. and in point of fact, I find the plants with foliage that contrasts with the flower color are generally the more valuable ones as finished garden plants.
No clue as to how commonly that happens… I am several steps away from having seedlings that I would consider market-worthy.
I hear you, Peter… I was somewhat excited about an orange seedling this spring until it occurred to me that it was a lack of chlorophyll that was allowing the other colors to show. The first true leaves started out largely pinkish, and then it perished…
Could this be the result of white (at least seemingly sometimes) being a dominant colour cancelling gene/s (affecting bloom but not plant) rather than the a recessive absence of colour gene/s.
In some cases, I think, yes. But I suspect it’s a bit more complicated, although I should let someone with more knowledge answer that…
My “favorite yellow flowers” for instance, are largely so only because they are held above dark, bronzed, young foliage. (I don’t know that a “white gene” knocks out the red in the flowers in this case, but I’m in over my head.)
At any rate, I recognize that the same blooms over yellow-green leaves would probably not impress, and might even read as a sickly plant to me from a distance. (Having said that, I do enjoy a good chartreuse foliage as a contrast to bronze and purple foliaged plants, so I don’t mean to disparage a color. I just haven’t yet seen such in a rose to make a positive impression on me…) It is the context of the setting of the flower against the leaf that can really make it sing, and so I think, upon reflection, that while the generalization of a correlation b/w foliage and flower color might have some merit, pursuing that assumption could potentially eliminate plants having strong impact in the landscape.
It is easy to forget to focus on foliage when breeding for the bloom.
Having said all that, I generally like dark foliage, and will probably continue to get excited over heavy anthocyanins in seedlings. 
(I know better than to listen to my own advice – I just like to share it with others liberally if only to see if it actually has any merit.)
[Off-topic: Has anyone ever seen a “chartreuse-foliaged” rose that has a modicum of attractiveness? Do roses have potential for such? There are a host of plants in this color group that are quite popular, having names like “key-lime,” “lemon,” “golden,” or having “aurea” in their nomenclature…]
Yes. I would say the trait inhibits red-pigment synthesis in the petals, but may allow it in the stamens within and leaves below.
For example, Mansuino (1960) crossed ‘Tom Thumb’ with Rosa banksiae lutescens. A white flowered offspring was then crossed with ‘Lamarque’ (Blush Tea-scented x a Noisette) which is also white (with some yellow). This resulted in “a Banksiae type bearing beautiful deep rose colored flowers.” At least one of the parents must have carried a dominant white (or “non-red”).
http://bulbnrose.x10.mx/Roses/breeding/Mansuino/banksiae.htm
Another possible example is ‘Allard’. Prof. Allard raised OP seedlings from ‘Harison’s Yellow’. These generally resembled the Scot’s Roses, and bore “simple flowers, white, pink, yellow and one with semi-double flower, having the color and the same tone as the Rosa lutea Miller.” This leads me to guess that ‘Harison’s Yellow’ was raised from Rosa foetida lutea and a double pink Scot’s Rose.
http://bulbnrose.x10.mx/Roses/breeding/Allard1900.html
I’m precociously senile, and apparently didn’t archive some of the better links to color genetics in flowers written for the layman. Can anyone redirect me to such?
And as an aside, would there be merit in creating a searchable rose-breeders wiki linked to this site where info such as this could be collected? I know that I have frequently resorted to trying to do searches within this forum to try and find stuff I vaguely recall reading about, but which I did not archive.
Unfortunately I don’t know of any good simple explanations for flower color in a complex mix of polyploids such as most roses. I think you have to make tables of empirical observations and go from there. For sure it is not simple Mendelian inheritance, although that would allow for some examples cited above. For instance suppose that red is dominant to white so that you don’t get pink if you have one chromosome carrying a gene for an essential enzyme in making red color, but red. Let the plant be diploid, Now suppose the parent of the hip is red but heterozygous at this locus. Then suppose it gets pollen from another heterozygous parent that is red but missing the same enzyme. Of course 1/4 of offspring will be white. In this example the pollen donor might be the hip parent so this is essentially a self cross. Or it could be a cross with a fairly close relative having the same gene combination.
Now consider a plant that has a missing enzyme A encoded on one chromosome and a missing enzyme B encoded on its matching partner. If red is dominant at both enzyme steps, the flower will be red. But in a self cross some of offspring will be white at enzyme A, while some will be white at enzyme B. Do we allow crossing over to happen during gamete formation? If so with what frequency? The amount of crossing over will determine the linkage of the two enzyme traits. If there is no linkage, the two genes might as well be on different chromosomes. If there is very tight linkage we might only very rarely ever see the consequences of crossing over. In between we will see different amounts of progeny that are actually white, inheriting the recessive trait at both enzyme A and B, or A along or B alone. It woudd take a huge number of crosses and rasiging of progeny to sort out this simple case.
Now consider a tetraploid. Then allow for intensity of red to vary with the amount of enzyme A. You will get 4 classes of offspring by color in a second generation, having 4,3,2 or 1 copy of the enzyme gene.
However, we know that there are multiple enzymes needed to make red all the way. SO we can have blockages at multiple steps. We will have different intensities of red according to the rules for each enzyme, in combination with the next for whatever the length of the path…
If we have master regulator genes for whole pathways, or attenuator genes (such as RNAi) of one sort or another, the possibilities become very big.
This of course only considesr that the whole petal behaves the same. But we know that front and back, base and tip are controlled differently. Then the “eye” and the “blotch” and the picotee need to be considered. Fortunately we don’t have regular stripes like petunias, or different color petals like sweet peas.
No, I can’t think of any way to make it simple. When I first started I thought there was a gene for yellow, a gene for red and everything else was pink. That was the impression given by stories (fables?) of how yellow roses came to be. After 20 years or so I figured out it wasn’t that simple.
David, I do not know of any information regarding your question with rose color. However, you might be interested in some similar information from a different genus. Somewhat similar to roses, snapdragons come in shades along a purple-red-pink-white spectrum, and also variously in yellow, and flower color in the genus is based upon multiple genes.
I used to have multiple inbred strains of snapdragons, donated by a seed company, which they used to produce “hybrid” snapdragon seed, similar to the “hybrid” corn seed produced by some seed companies. I used these to teach my students about genetics and also about flower parts. The company donated seed from 4 inbred lines: one white, one off-white, one red, and one dark red. At least one (and possibly both) of the red-flowered lines had very noticeably purple-tinged stems and leaves, while the light-flowered plants did not. I think this may have been noticeable from the seedling stage, but I don’t recall that with certainty.
Schwinn et al. “A Small Family of MYB-Regulatory Genes Controls Floral Pigmentation Intensity and Patterning in the Genus Antirrhinum” discussed a number of genes that control flower color in snapdragons, but two of the genes are of particular interest. One gene reduces anthocyanin in the flowers and also in the leaves and stems. The other gene also reduces anthocyanin (although less so) in the flowers but interestingly leaves abundant anthocyanin in the vegetative parts of the plant. So reduced anthocyanin in this genus’ petals may or may not be associated with reduced anthocyanin in leaves and stems, depending upon which gene is causing the lighter flowers.
Other species (perhaps including roses) may similarly have genes that reduce anthocyanin in just flowers, and others that reduce anthocyanin plant-wide. Such genes could explain Kim’s observations regarding flower and leaf color.
In the discussion on HelpMeFind about the proper identity of “San Leandro Dark Red”, one suggestion is the ‘Daily Mail Scented Rose’. Both are very dark red and fragrant, but the pedicels of SLDR are red whereas those of DMSR are green.
Looking at the early spring growth on some of my plants, I had an epiphany: It appears the cotyledon colors of seedlings might correlate with the first flush of new growth on the adult plants. (I don’t have statistics to bear that out, but looking at “average” seedling color right now, and comparing to parent spring-growth color, there seems to be a pretty strong correlation.)
I don’t see an obligatory link to flower color. A common correlation, yes. But, while my e.g. Carefree sunshine and Lemon Fizz have brighter green new growth, Soul Sister has decidedly deep wine-colored leaves (SS’s flowers are nicely offset by cool dark green and bronze foliage when it starts blooming), and my Softee growth has a definite flush of iron-red right now. (Some of my Softee seedlings right now surprised me with dark bronze tones in the cotyledons. Lemon Fizz seedlings have not shown any reds yet for me.)
As an aside, I haven’t bred with it yet, but Fire Opal has had some of the first leaves to emerge, and I’m blown away be how pretty (if almost fake-looking) they are. Haven’t used yet, and I’ve not seen OP seeds on it. Anybody have experience with it?
David, I just checked and I have six seeds (from four hips) from a cross onto Fire Opal. Given my germ percentages there is not a great chance of getting a seedling.
Here are just a couple representative packs of some of the polyantha seedlings to highlight the findings. The pack on the left had richly colored seedlings and the pack on the right from the same batch of seed had more normal seedling color. There isn’t too much in bloom on the left, but you can see a light colored bud. It seems like there isn’t any different in terms of translation of seedling color in these polyanthas at least to flower color later like some have suggested. Some of the seedlings with normal color at first did develop more reddish colored stems, but generally there may be more red in the stems carrying over from those that were reddish as young seedlings. I was hoping for a way to better select the more richly colored blooming ones early on.
Thanks, David. That’s very interesting. I would have expected a little more correlation towards darker foliage/redder stems on the seedlings that exhibited high anthocyanins, and would have thought there might be a slightly higher inclination towards red hues in their blossoms, though not obligatory. I gather you are saying that such is at best minimal? I think you just stuck a pin in one of my balloons. I would never cull based on seedling color at this juncture – as I say, I kinda hope for contrast between foliage and flower – but I do get a little more excited when I see a colorful radical or cotyledon.
I have a seedling from a striped parent having one cotyledon that is largely albino. I was wondering if that might be indicative of the striping that will (hopefully) later appear in the blossoms, but that actually seems to me less probable than my presumptions about seedling pigmentation…
There is also a species Rosa beggeriana (I know you have heard about it) white flowered, red stemmed.
Just a bit of observation connected to this…possibly too early to deduce anything.
I planted a bunch of r. persica seed earlier this year, assume collected from Kyrgyzstan, Kara-Buura 1200 m above sea level. The colouration of the sprouted stems was inconsistent, some red, some green…expecting a little more uniformity from species seed so was skeptical. Some of the seedlings are now several true leaves in and they are simple leafed of an unusual shape/texture which is probably a sign they are pure persica as hybrids have all seemed to be reported as having compound leaves. So stem colour may not be much of an indication of anything.