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Secondary Axillary Buds in Roses?

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Secondary Axillary Buds in Roses?

Post by Admin on 22nd January 2009, 01:34

I was reading a paper on the relocation of genetic material in sported mutations from somatic tissue that is not involved in the formation of sex cells to tissue involved with the development of sex cells ([You must be registered and logged in to see this link.]). In it they simulated the effect of grazing on the relocation of sported (mutated) DNA. To cut a very long story short they showed that the simulated herbivory could cause the relocation of mutated DNA from non-reproductive tissue layers to reproductive tissue layers. Removing the primary apical shoot forced the secondary apical shoot to develop and these often showed, by tissue analysis, that the mutated cells had actually jumped from one of the non-inheritable layers of tissue (there are two of these) to the layer where it could and from that point onwards it could influence the evolution of that species because it was now inheritable. This got me thinking... obvioulsy this article is not about roses. Roses do, however, sport quite frequently, some more than others (like Mary Rose and Iceberg). Sometimes the sports are sufficiently different to the original that we want to keep them and propagate them. We do so vegetatively by budding or cuttings of the sported section but the mutation may not be inheritable so it would still breed like the original plant. In some cases the sported feature clearly is inheritable as in a lot of climbing sports that throw climbers when used in breeding. Problem is, I don't recall ever noticing whether a second bud has ever come out from the same place one had already grown and been removed... I don't know if these secondary buds even exist in roses. Has anyone ever noticed a second bud growing from the same place another had been removed from? If so by cultivating a sported variety vegatatively and then removing the terminal buds and the primary axillary buds to force these secondary axillary buds to form one may be able cause the mutated cells to switch layers (there are three of these layers as mentioned in the article; L1, L2, and L3) into the reproductive layer making that feature inheritable from that point onwards??? I've done a cross as an experiment this year to see what happens when Burgundy Iceberg is crossed with the original iceberg. One theory says the Burgundy Iceberg will breed like the white original cultivar. Another theory is that the mutated cells may now be influencing the development of sex cell and it will breed like a burgundy rose. Maybe the original sports actually occured in L2 and were inheritable all along??? I guess a flaw in this experiment might be related to what this article is saying in that it might first depend on where the the flower forms in the first instance and under what circumstances. If I get all whites this time around I think it could be a good exercise to try it again but this time try and force these secondary buds if they exist in roses. Would welcome anyone's input on whether they've noticed these secondary buds forming in roses.

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Re: Secondary Axillary Buds in Roses?

Post by Admin on 22nd January 2009, 02:25

Took a photo of a Climbing Iceberg stem tonight because I noticed these two buds:

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Now in the process of finding out whether they one is a primary axillary bud and one is a secondary axillary bud or if one of these is just what the authors call an adventitious bud.

I'm getting a lot of semi-reverted flowers on my Burgundy Iceberg at the moment. The plant seems to be under stress from black spot at the moment.. so maybe this has something to do with it.

[You must be registered and logged in to see this link.] [You must be registered and logged in to see this link.] [You must be registered and logged in to see this link.] [You must be registered and logged in to see this link.]

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Re: Secondary Axillary Buds in Roses?

Post by rosemeadow on 25th January 2009, 12:00

I read your article TasV. So do you mean a cell can jump from one plant to another, and start itself living on the other plant. Then make it so that part of the plant can grow more bits like itself. Nature's way of grafting or budding.
Dao told me when I visited him that each bud has a hundred or hundreds ( can't remember exact what he said ) of little buds around it. So if you take that bud out and transfer it to another rose than you first rose will not be able to grow a new bud ( as with prepared rootstock for for grafting ) unless all around the bud was not taken completely. You could do this diliberately, maybe, so you could remove the bud to graft but also leave some of the buds to go on living on the original plant. Is this kind of what you were talking about ?

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Re: Secondary Axillary Buds in Roses?

Post by Admin on 25th January 2009, 14:55

It's probably not hundreds of little buds but it's certainly more than just the one we see growing in most cases. We need to be certain we are talking only about axillary buds and adventitious ones as well.

So do you mean a cell can jump from one plant to another, and start itself living on the other plant.

It's not exactly what they mean. Plant tissue is divided into 3 layers that they call L1, L2, and L3. The cells in these different layers are isolated from each other and because of this cells in each of these layers are able to have a slightly different genetic makeup to the cells in the other layers. They call this a chimera. Variegated leaves are often (but not always) caused by cells in these different layers having a different genetic makeup (genotype) in one part of the leaf compared to another. Sporting is another example where a mutation can occur in a layer such as L1 and L3 that will affect the appearance of the plant but sex cells (i.e. pollen and ova) are generated by the L2 layer and if the mutated DNA is not found in this layer then it will not be inheritable (and thererfore no use to hybridisers). For example, you take the 'Burgundy Iceberg' above. The "Iceberg' line is prone to sporting. The orginal white 'Iceberg' sported the 'Misty Pink Iceberg', which sported the 'Brilliant Pink Iceberg' which sported 'Burgundy Iceberg'. There is a good chance, however, that if I was to use 'Burgundy Iceberg' in a cross that it might breed just like the original white one because the mutation might have occured in either the L1 or L3 meristematic layers. So when I read this article I started thinking... in a nutshell, what my interpretation of their results is that if you have a variety that is itself a sport and you remove the terminal bud (top one) and the resulting primary axial buds as they develop, then you are forcing the secondary axial buds to sprout and the results in this paper indicate that the organisation and duplication of cellular material in these buds is less accurate that in other buds and they have been able to cause the sported genetic material to jump from either the L1 or L3 layer into L2 (because it's less accurate or more prone to organisational errors) where it can therefore incorporate the sported DNA into the pollen and the eggs (ova) and therefore into the seedlings of self pollinated plants. That would mean that if we could encourage this to happen in sports that we want to sue in breeding we could improve our chances of making the sported variation inheritable and therefore of use to hybridisers. This is why I did the test cross between 'Burgundy Iceberg' and the original 'Iceberg'. If there is evidence of purple in the seedlings then it shows that the mutation is already inheritable. If I get mostly whites and maybe pinks (as in the 'Iceberg' lineage) then there is a good chance that it is not inheritable. If it isn't inheritable then I might try to see what would happen if I removed the terminal bud and then, when the axial bud(s) formed I rubbed them off and then if further shoots came from the old leaf axil then I would allow them to grow and flower and use the pollen from these flowers to again pollinate the original white 'Iceberg' to see if it actually works. If THAT works then maybe one could assume that the whole branch from which that pollen came from now has the mutated DNA incorporated into the L2 layer so theoretically if buds or cuttings were then taken from that portion of the plant then the whole plant might then have the mutated DNA and actually be of some use to hybridisers to say pass on the vigour of the 'Iceberg' clan to other less hardy roses etc...

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Re: Secondary Axillary Buds in Roses?

Post by Ozeboy on 25th January 2009, 15:54

Very interesting would like to see the results of the Iceberg cross.

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Re: Secondary Axillary Buds in Roses?

Post by rosemeadow on 26th January 2009, 11:17

Thankyou Tas, I have a bit more knowledge about how roses grow now and some understanding of your experiment.

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Re: Secondary Axillary Buds in Roses?

Post by Admin on 5th February 2009, 01:29

I have a lot of trouble actually getting 'Iceberg' to set seed. Had a quick look at the hips today and they look OK so maybe they will have a few seeds in them... I put 'Burgundy Iceberg' on a few other things too so with any luck if this one doesn't take then one of the others will. I never get any OP hips on any of the bergs either.

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Re: Secondary Axillary Buds in Roses?

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