Differences in phenotype do not necessarily mean differences in genotype. The plant most likely has the same DNA throughout (barring rootstock) but some genes are more active in some parts than others, resulting in the differences you see in the flowers. If the cane with the different flowers maintains this difference on all new growth emanating from it, then it's likely that whatever difference in gene expression causing it may be relatively maintained via vegetative propagation. But from what I've read, striped sports are notorious for not being very stable -- not all, not all the time, but a good number of them.

:-)

~Christopher

As the canes and blooms grow there can be slight mutations that cause the differences in the blooms. And weather conditions can effect that expression. A true sport will retain that mutation even when propagated by cuttings. Otherwise it is not a sport but just an aberrant bloom. And a lot of sports will later revert back to the original rose from time to time. It just depends on how it decides to express the genes as it grows.

That reversal of color in Scentimental has occurred previously, Harmony. An identical mutation also occurred on QE76STR, a Queen Elizabeth striped seedling of Ralph Moore's. Both originated as white with darker stripes and both mutated to dark with white stripes. As Christopher said, the genetics may, or may not be the same between the two "versions". Usually, the mutation is only "skin deep". Breeding with both versions most often results in identical results as the change usually doesn't extend to the sexual level. Kim

Scentimental throws sports quite readily. Some roses just do that. I grow a Scentimental Sport that has orange stripes that is now registered under the name "Special Effects."

And easy come, easy go. If it throws sports quite readily, it probably also reverts with that same ease. That's the problem with Simsalabim. It comes and goes, and mostly tries to go -- back to a plain old yellow rose.

Here is a link that might be useful: My Special Effects on HMF

Would each bush be consistent with itself in the blooms, or would they tend to vary, flower to flower on the same bush? Regan had about 8 Scentimental bushes, and I'd swear each was different from the next. Will they stay like that, or do you see what you get each time a bud opens?

We had that dark Scentimental, too. I rather liked it, but over time, I found it not to be as strong-growing a plant as the original.

That, of course, may not have been the fault of the sport. It may just have been a cr*ppy plant. ?Quien Sabe?

Jeri

Each flower on each bush varies quite a bit from each other. That's part of the serendipity of striping. Each flower is different from all others, even though they fit basically the same description. Kim

If a rose is notorious for sporting frequently, and if those sports are notorious for reverting, does it make sense that the change is due to a genetic mutation? Of course not. The DNA is the same, but the level of expression changes.

Otherwise, what the claim is really stating is that a random mutation occurred, changing the DNA sequence such that now its flowers are different, and then randomly mutated back to the original DNA sequence, but everything else remained exactly the same. The odds of that happening are astronomical -- clearly not the accurate explanation of something occurring frequently. What's more likely is that as cells differentiated to form new top growth, the 3-D structure of the DNA (but not its sequence of nucleotides), which had to change anyway during cellular differentiation, didn't EXACTLY match the same 3-D structure in one branch as another, resulting in some genes being expressed at slightly different levels from cane to cane. Since the 3-D structure of DNA in the cells repeatedly changes as the cells differentiate (from stem to bud, or stem to root), there's much more possibility of this kind of variation going back and forth than that the actual DNA sequence changes and changes back again. If the DNA was that unstable sequentially, the plant likely couldn't survive.

:-)

~Christopher

This post was edited by AquaEyes on Wed, Apr 24, 13 at 23:15