Here’s the text [the article is about breeding using species]:
"The primary importance of breeding with species is the introduction of resistance to fungal disease or insect pest into the garden roses. Some successful results are referred to above. But other character traits could also be improved by species crosses. Breeding with R. foetida (R. lutea var. persiana) resulted in yellow rose cultivars for the first time. The other yellow species (R. hugonis, R. ecae, R. primula[/i]) could be included in breeding programmes to improve yellow flower color with winter hardiness.
In roses, yellow flower colour is caused by lipophilic carotenoids of the chromoplasts. These are inherited maternally, therefore only crosses with yellow seed parents are successful. At p. 311.
W. Spethmann, University of Hanover, Germany. His email is online. spethmann at baum.uni-hannover.de
Well there is the source of the poor information. Spethmann is right about the inheritance of the plastid genome, but … While the plastid genome that gives rise to chloroplasts, amyloplasts, chromoplasts is inherited through the seed parent (there are some exceptions), in other plant species where the genetics of this pathway have been extensively studied there are numerous nuclear encoded genes that are involved in the biochemical pathway that synthesizes the carotenoids. I really doubt that roses are the exception. Anyway, just my two cents, Liz
two cents from germany, joining those thrown by Liz.
I think thats right. …
If there would be at least two traits for different kinds of yellows (light and deep ones e.g.)- even in that one section of the spinosissimae - it would be no wonder to me, to get different explanations from different authors.
Maybe I’m missing something, but that yellow does not seem very deep. The seed parent has a stronger yellow. Is that your point? On the other side of things, Hazeldean is a relatively strong yellow arising from a light-colored seed parent. Almost certainly the intense yellow came from the pollen parent or pollen grandparent.
It could be the light yellow from the Canary Bird line that is crossed in per Pollen of Golden Chersonese in your crossings.
The deeper ecae yellow would be perhaps possible if one takes ecae as a mother plant.
I will take ecae (and Golden Chersonese) as a mother plant this year, its not a big shrub, the one I have here, but good enough.
By the way, I crossed with Golden Chersonese, too, and have already got 4 Seedlings out of this crossing from last year:
Rosa rugosa ‘alba’ x Golden Chersonese
Not difficult, as you know, rugosa is a good seedparent.
But its a section cross between cinnamomeae and spinosissimae.
It will be very interesting, to see, what colours will derive out of this crossing, - to be honest, thats the only reason, why I did it: I want to know something about the colour-inherities of the possibly different traits of yellows.
“Differential pairing of chromosomes does play a role in the reduced fertility of some hybrids, and can greatly reduce the frequency of segregation of characters in the hybrid progeny. That is, if we cross Rosa foetida with a Hybrid Tea, we cannot expect fully fertile, deep yellow Hybrid Teas in the F2.; and it will take even longer to eliminate the susceptibility to blackspot.”
The possibility of differential pairing of chromosomes should play also a big role in Hulthemia and perhaps banksiae crosses.
Wow, this makes it pretty difficult.
Perhaps the best is really to throw with pollen around and think less.