Rick, I've run across this idea more than once, that cuttings or budwood taken from different parts of the plant can produce new plants of different quality. I have to say this seems dubious to me on theoretical grounds--all parts of the plant have the same DNA unless there has been a mutation. However, some experienced propagators feel they have evidence to the contrary.

Seeking out a superior mother plant is a different issue. One plant may carry more viruses than another, even though many viruses are invisible/asymptomatic. Or one clone may carry more invisible little mutations than another.

Michaelg, it is true that "all parts of the plant have the same DNA unless there has been a mutation" but it's not the case that all parts have the DNA expressed equally. There are almost certainly epigenetic differences which lead to some genes being more "turned on" than others with respect to the part of the plant. For example, every cell will contain the genetic information used for flower production, but in root cells, that information is not "turned on" to the same degree as in flower bud cells.

When growing a clone, it's very likely that the sample taken to grow on will maintain some of this "degree of turned on"-ness with respect to where on the plant it was taken. While it's likely to be true that the DNA is all the same as far as sequencing the neucleotides, the structure of the DNA can vary with respect to its 3D shape (parts of the DNA bent into "knots" will be less likely to be transcribed than more "open" stretches of DNA) and molecules bound to it (some proteins facilitate transcription, others inhibit transcription).

Plants can be very flexible with regards to how their cells differentiate, go back to undifferentiated forms, and re-differentiate. This allows us to make asexually-reproduced clones from cuttings -- what was once a stem can generate root cells by re-configuring which genes are "turned on" and "turned off". But if the top growth arose from a cutting which has more of the "bloom-genes turned on" then its likely that as it grows, new top growth will maintain this pattern.

I have no experience in studying this to detail the precise mechanisms at play, but I am familiar with enough animal genetics to understand what MAY be working. I'll give an example....

Do you remember the first domesticated cat to be cloned from body cells derived from another individual? Interestingly, the original was a calico. This color pattern results when cats have one copy of the "black fur" gene, and one copy of the "orange fur" gene. Since these genes are located on the X chromosome, cats having one of each are (almost) always females (sometimes males are born as XXY, but this happens, I think, about 1% of the time).

In mammals, only one X chromosome is fully active -- males have only one, so they're fine as-is. Females have two, so early on in embryonic development, when they are at the multi-cell stage, one X is "silenced" (mostly....a few genes remain active which are responsible for sexual maturation, but that's another topic) at random. Usually, roughly half the cells have the maternal X turned off, and the other half have the paternal X turned off. Thus female embryos are a mosaic of cells, with some having mom's X turned on and other cells having dad's X turned on. As each cell divides, this "active/inactive" pattern is maintained in each successive generation of mitosis.

When each X has a different gene for fur color in cats, the result is that we can see the phenotypic effects in the skin cells -- patches of orange and black fur (the white patches are due to a white-spotting gene unrelated to the orange and black, and "tortoiseshell" is the name given to orange and black cats without the white). While all female mammals are likewise a patchwork of "paternal X on, maternal X off, and vice versa", tortoiseshell and calico cats offer a rare visual example of this phenomenon.

OK, so the cloned kitty....well, the cells were obtained from a patch of skin on the calico cat with black fur. Despite the fact that the original cat had patches of orange, black and white fur, the cloned offspring did NOT have any orange fur. The DNA was the same, but being as the skin sample was derived from "black-on, orange-off" cells, the cloned kitty was made entirely of "black-on, orange-off" cells. Genetically, she is still a calico. But phenotypically, her "orange-gene" is silenced.

I'm thinking that a similar mechanism is at play when "selective propagation" can result in an "improved" version of an original.

:-)

~Christopher

This post was edited by AquaEyes on Sat, Apr 20, 13 at 12:39

I vaguely thought it was something to do with meristems - that is, cells which have the ability to change their active growth (from leaf cells to root cells or summat like). I appreciate I have absolutely nothing to contribute to this debate.....but definitely recall reading Christopher Lloyd on rooting internodal cuttings (as with clematis).
I managed to get a T.bud to take at the same time as the canina cutting rooted, using only about 2inches of rootstock cutting.......but this was under a mister at college - I thought it was a pretty nifty, time saving method but never managed to replicate it at home.

Thanks to Christopher. The cat example is really cool. But it remains the case that plants grown from root cuttings develop normal leaves and flowers, etc.

Yes, this is true. I was trying to think of the mechanism which may be responsible for the phenomenon of "selective propagation" which has been observed.

Think of it like this -- to produce flowers, certain genes need to be active to produce their ingredients. To produce more flowers, more of some ingredients are required. If a cane "sports" to be more flowering than the rest, a genetic mutation may not necessarily be the reason (although it could be). It could also be that one or more of the genes making the "flower-producing ingredients" is/are more active in those cells. If that difference relates to epigenetic changes which can be transmitted to future growth via mitosis, then taking a cutting of that piece will result in "bloomier" plants.

When you take a cutting, cells at the base reconfigure their DNA expression to produce roots. But the top part maintains whatever DNA layout it has to continue producing "top growth." It's possible that "selective propagation" would be more successful using budding/grafting, so that all future canes derive from top-growth rather than new shoots from the base, which would have to undifferentiate and then re-differentiate to form new top-growth and (hopefully) "remember" the "bloomier" epigenetic changes. But as this has been seen in propagating other "bloomier" sports on their own roots, it isn't always necessary.

Plants which can reproduce asexually have a better ability to "unwind" any epigenetic changes to differentiated cells to make them undifferentiated, and then re-differentiated to form different growth. This flexibility is not as built-in among mammals, making cloning of them more difficult. In plants, this very "flexibility" is what allows us to root cuttings and make new plants. But it's also this "flexibility" that allows plants to throw phenotypic "sports" which will vary in appearance, but not necessarily in their DNA sequence. If people spot these "sports" and manage to coax the cuttings to grow and maintain these differences in DNA expression (without having differences in DNA sequence), new selections may be made via asexual reproduction which vary phenotypically but not genetically.

:-)

~Christopher

Thank you Michael, Christopher and Campanula.

Michael, I find your idea of minute mutations in different clones as a possible explanation for expressed differences in plants of the same varirety over generations intriguing. I have a keen interest in cold hardiness and lavenders because I grow them both in a climate that is at the edge of their tolerance. I have noted over the decade I have gardened here especially in lavender, but also in roses, that plants grown from cuttings of parent plants who have been grown in my climate and survived for several years tend to be much hardier than plants imported from warmer areas. Annecdotal observations for certain, but never the less discernable and interesting.

Christopher, thank you for the comprehensive explanation regarding gene differnciation in different parts of the plant. Your argument causes me to think that it is at least possible. I happen to have a plant of Geoff Hamilton, a beautiful, healthy cultivar which does not bloom a lot for me. It is also a cultivar where I hear many people say it is a poor bloomer, but a significant set of others who say their plants are excellent rebloomers. GH is on my last chance list for this year. So I think I shall use it for an experiment to test this hypothesis. I shall strike cuttings from wood as close to the flower heads as possible and grow them on. Of course it will take three or four years for them to mature, but never the less, it will be interesting to test the theory.

Cheers, Rick

Would half-hardened stems after flowering have their "floweringness turned on" or would they have hip formation or new vegetative growth turned on?

Is it true that minor sports like changes in flower color or doubleness are often changes at the level of phenotype rather than genotype? I would think the answer to that question is available nowadays.

Incidentally, back to the original post, the claim that I have often seen is that one shouldn't propagate from blind shoots. In most cases, blindness is simply caused by envoronmental things like insufficient water or some damage to the underlying cane. Also, some varieties tend to start more shoots than the plant can properly support. Possibly blind shoots have less carbohydrate fuel in them than flowering shoots, which might make cuttings less likely to strike root, but I'd guess that would not affect propagation by budding. I wonder whether the inferiority of blind shoots has been tested, or whether it is something propagators take on faith because it sounds like it might be a true idea.

Dr. J. H. Nicholas reported in his 1937 A Rose Odyssey, the American stock of Gen. Jacqueminot had been nearly ruined by propagating from climbing, blind wood. He stated American plants of that variety were predominantly climbing and provided little bloom. He continued as is stated in this reference on HMF,

"A Rose Odyssey

Book (1937) Page(s) 14.
Several years ago there was a discussion in American Rose Society circles about the genuineness of the American stock of General Jacqueminot. I studied the question abroad and found at Reymond's a line of magnificent everblooming General Jacqueminot, descendants of the original stock he had inherited from his Uncle Roussel, the originator. These had been improved almost to the status of a Hybrid Tea (sic) in floriferousness. We acquired enough plants from Reymond to rejuvenate our stock and the General Jacqueminot stock of Jackson and Perkins is of authentic French origin."

The implication being that bud selection made the difference. There have been other statements in the rose literature of propagators being able to "force" climbing plants from bush types by selecting immature buds from low on mature canes. I attempted bud selection with Graham Thomas for many years in an attempt to develop a more heavily flowering plant which didn't demand a house to eat to accomplish it. I probably gave away and shredded two dozen plants in that attempt, which failed, BTW.

I have noticed cuttings from the same plant varying quite a bit in their ability to form sufficient root systems to produce decent plants. Most often, those cuttings from recently shattered blooms have made the most vigorous own root plants. If it won't make good roots, it can't make a decent plant. Kim

We can perhaps widen this to outside the world of roses. Don't cuttings of Algerian Ivy (Hedera canariensis) taken from the part of the plant which has achieved the mature, "shrubby," form preserve this mature shrubby form rather than to revert to the familiar vining form?

Understand that I have no personal knowledge of this: On one of the fruit forums here (probably Citrus or Fig, possibly Tropical Fruit) there were recommendations to take cuttings from high on the tree rather than near the base of the tree because, it was said, that the higher cuttings bore fruit more quickly. I presume that would mean it bore flowers as well more quickly. There were detailed explanations of why this was so but I don't remember them now.

Cath

Hmmmm, I also take cuttings from a non-rose plant (I am not going to waffle on about here) and always go for lower on the plant because a: the woodier growth is much better on this fairly fast rooting plant at holding together until rooting occurs and b: I can usually take a strip of woody bark (A heel) which is where (presumably) more meristemmatic cells are collecting.

As for roses, I am usually looking to take a branch which has recently flowered but the actual cutting wood is where the flowering branch meets the main cane (an apical summat - sorry to be rubbish at botanical terms). Sometimes, this means taking a hefty branch of flowering wood (to the annoyance of friends who have told me to 'go right ahead, take what you need').

I think what I am trying to say is that although the entire plant possesses an overall DNA signature, there are definite sites on plants which are predisposed to break into growth (such as internodals on clematis, rather than apical sections) and these vary, plant by plant - we find them by trial and error..

We can perhaps widen this to outside the world of roses.

Gardenias are common around here. They bloom heavily in the spring and fall since they need cool nights to set buds. But they do give an occasional flower during the summer.

I've never done it, but I've wondered if I were to root one of those summer flowers if I'd get a plant that would be more willing to bloom in the warmer months.

That would depend upon whether that summer flower was stimulated by an odd weather anomaly, particular suitability of its micro climate or a genetic mutation toward more repeat flowering. In the case of the first two, there would be no improvement toward summer flowering, but in the latter, definitely! That's how things such as Blaze Improved and New Dawn were discovered and selected. Both were once flowering until someone noticed blooms out of season and began propagating them to isolate the repeat flowering. Kim

This is fascinating.