Scottish Rock Garden Club Forum
Bulbs => Galanthus => Topic started by: annew on February 22, 2015, 06:46:52 PM
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I'd like to get other growers' (and chippers') experiences on instability in snowdrops, most notably (but not exclusively )in inverse poculiforms, or 'iPocs'. Maybe the purchaser of 'Golden Fleece' needs to read this!
These are my observations:
Normal-form snowdrops (examples - Magnet, Bill Bishop) are completely stable when chipped, never showing any variation from the normal form.
Poculiform snowdrops (examples Angelique, The Bride) are completely stable, although I haven't had many of these to try.
Virescent snowdrops ( Greenish, Virescens, and several other unnamed ones I grow) are completely stable, so far.
Green-tipped snowdrops (examples Dreycott Greentip, Scharlockii) are unstable - many losing the green markings on the outer segments. I don't know whether this is permanent. It is my belief that Dreycott Greentip and Scharlockii are very closely related, as DG's spathe regularly splits like Scharlockii, and Scharlockii's spathe occasionally does not split. I have planted out about 50-60 of each variety which had been in baskets, showing a majority of unmarked flowers for several years. As they flower in the open ground, it seems that the majority now are showing the green tips. Spathe splitting is still irregular though. In addition to these two varieties, a green-tipped nivalis from Cliff Curtis and Jessica have also lost the green tips, in Jessica's case every chip except one has no green tips!
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Inverse poculiform snowdrops (examples Trymmer, South Hayes) show some instability and can completely, and irreversibly, revert to the normal form. Seemingly stable are Corrin, Trymlet and Trym. Definitely unstable are Trymmer, David Baker, and sometimes South Hayes. The original South Hayes that I bought, that turned out to be a normal flower, has not shown any sign of converting back after 7 years.
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Snowdrops with green ovary, and yellow inner marks (examples Blonde Inge, Lady Elphinstone) can lose the yellow marks, reverting to green. I don't know whether this is permanent.
A whole tray of Blonde Inge is without yellow marks. Lady Elphinstone is a curious case. My original plants used to produce about 5% of flowers with yellow inner marks, even though they have been undisturbed (the usual reason given for reversion) for 15 years. In 2009 I bought 3 new bulbs from a seller on ebay who assured me his came yellow every year. Despite my scepticism, I planted 2 and chipped one. The planted ones have increased and now have about 15 flowers, all yellow-marked. The chipped ones are just opening their first flowers and 1 of the 3 flowers so far is green-marked. Of course I don't know whether the new bulbs were decended from chipped bulbs, or from natural division.
To finally confuse things, one bulb of a seedling of South Hayes which looked similar to the parent last year split naturally into 7 daughter bulbs. I potted them all together, and each one has a different flower this year….
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In conversation with an enthusiastic "chipper" last week, she said that she did not think that it affected markings, but that twin-scaling might, to a degree.
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I only chip my snowdrops, never twin-scaling. Fortunately daffodils seem to be immune to this kind of variation! :)
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By the way, I'd like to reassure potential customers that I only send out plants which have flowered and been verified correct. I'd advise seeking a similar assurance if buying from any nursery.
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It's really interesting that you are finding that with chipping and not with twin-scaling. Hopefully someone else with experience will come back to you on this. You can understand this with twin-scaling as presumably a bit of the genetic material could be missing on a twin-scale, but you would have thought that chips would have been more stable.
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As I recall, David Quinton had a 'White Hayes' and Jo Hynes tells me she gets an occasional 'White Turbine'. These are both i.pocs, normally with a central green "stripe" - or no longer in the 'White' version. Jo had a theory that the white ones might result from bulbils developed from the top of the bulb whilst the normal ones had basal plate - but this was just conjecture.
I have offered-up a number of my novel nivalis i.pocs for chipping, possibly to the same 'enthusiastic chipper' Maggi refers to. I'll let you know the results, Anne, but I think these are a year or two off.
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Oh, and I would have thought your 'South Hayes' are just showing normal variation for small bulbs. I bet the marks will be different nest year.
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By the way, I'd like to reassure potential customers that I only send out plants which have flowered and been verified correct. I'd advise seeking a similar assurance if buying from any nursery.
I never doubted that Anne - we'd expect no less from you.
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My Scharlockii are propagating themselves by division and seed like mad, so I never thought of propagating them otherwise. Occasionally one of them has a spathe which doesn´t split, but this feature didn´t prove stable.
My established clumps of ´Blonde Inge´flower sometimes with yellow mark, sometimes not, sometimes only part of the clump. They´ve been propagated naturally.
A friend told me of a deliberate attempt to produce a white ´South Hayes´by twinscaling, but the results proved instable.
Anyway, to compare, You´ll probably need to grow all in the same soil and allow a few years for establishing. A more experienced twinscaler mentioned, that it may take 2-3 years of flowering for varieties like ´South Hayes´to show their typical features. The expierence of some buyers of such abnormal S.H was, instead, that they simply passed away.
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Some twinscalers say there is not enough DNA in the twinscale. This cant be correct. DNA to replicate must be in every cell
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Correct Mark, each cell should contain a copy of the DNA for the parent plant. What could differ is the plasticity of the cells?
Once a cell starts developing down a route to produce a particular type of specialised cell, there will come a point where it cannot go back. Stem cells are highly plastic, they could differentiate into any type of cell - i.e. cells for green petals, pterugiform petals, a leaf, a root etc. I presume that these unspecialised cells are found in the very centre of the basal plate. Some cells, towards the edges of the basal plate perhaps, might be more differentiated - i.e. they have started to specialise to only produce white petal tissue, for example.
Therefore, as a slice from every part of the basal plate a chip should contain cells that can become any/all types of tissue to make an new, identical plant. If you had a twinscale composed of the outermost scales of the bulb/basal plate, you might be missing some cells that are capable of specialising into the tissues you need to make all of the features seen in the parent plant, because there are no stem cells and/or the cells present are on a developmental pathway they cannot turn back from.
Just some musings. I'm not a cell biologist, but do have a background in the biological sciences (ecology, evolution etc)
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If the result of a twin-scale or chip might indeed be position dependent then the only way we will find out is if the person performing the operation places the chips/twin-scales into separate containers according to where on the bulb the piece came from and then tracks the progress thereafter. That would be a lot of extra work but an excellent science project.
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I tried to propergate the verified Frit. Imperealis by chopping. I got a really wide variety of verigation. I only have a few ov the coloured left Most reverted to green. Somebody with greater knowledge explained what was happening, something to do with the way the DNA was distributed in the cells.
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I should explain. Each of the leaves in the picture are a separate bulb.
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I tried to propergate the verified Frit. Imperealis by chopping. I got a really wide variety of verigation. I only have a few ov the coloured left Most reverted to green. Somebody with greater knowledge explained what was happening, something to do with the way the DNA was distributed in the cells.
That's an interesting result Susan (and disappointing for you as a nurserywoman).
I realised that my last post was relevant to the chip vs. twinscale problem, but didn't really answer Anne's original question, why plants propagated from chips aren't stable. I though that could be because:
1. The plastic/undifferentiated cells are not distributed evenly throughout the basal plate, i.e. you might have more stem cells in one chip and less/none in another.
or
2. The expression of features seen in the parent 'drop in chipped offspring are also affected by environmental conditions, either:
a) during the development of bulbils on the chips during incubation, which could lead to permanent changes in the plants; or
b) the growing conditions the resulting plants experience, which you might expect to settle down over time, plants revert according to regime etc.
As Alan says, a huge potential for experimental design to test some of these questions...given enough time and valuable snowdrop bulbs...
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Are there some cell lines in monocots ? Variagated foliage is often lose due to migration of a cell line in an other.
This is just an hypothesis but chipping mobilise undifferentiated cells and these cells might come from different cell lines. If the pattern of the snowdrop cultivar depend of different cell lines (as the variagated cultivar), chipping might lose one of this cell line and revert to an other cultivar. For example, invert poculiformis might come from an inversion of two cell lines, the inner one becoming the outer one. Chipping might lead to revert the order to the normal one (I'm sorry if it's not fully understandable, but this explanation overcomes my english's limits...).
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Have a look at John Richard's Northumberland Diary entry on the AGS website for 26th January 2014. He describes the basis of variegation in dicots (mostly) here in detail (Joe Sharman has given a similar talk to us in the past). Micropropagation runs into these same instabilities (chipping and twin scaling are effectively types of microprop. even if not dividing and manipulating plant tissue so specifically) because plant tissues are quite 'plastic' in the ways they develop (which is what enables them to be vegetatively propagated in the first place) and pigment production in flowers can, after all, be extraordinary (think of irises!). Anne's experiences are really valuable to know.
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I'm glad you all came up with comments! A few of my own:
South Hayes when reverted not only loses the green mark on the outers, but the shape of the flower is as a normal snowdrop, totally unlike a proper South Hayes. None of the reverted iPocs that I have kept for observation have shown any attempt to convert back to either the normal shape or colouring.
I too have theories!
As Karaba mentioned below, parts of an organism can have a completely different genome from the rest of it - these are called chimeras. The classic example of chimerism affecting propagation is in the houseplant Sanseveria. If leaf cuttings are taken from a variegated plant, the resulting plants will be all green. This is because the part of the leaf which produces the new plant is situated on the green part of the variegated leaf, which is different genetically to the yellow part. I wonder if chimerism is involved in the production of iPocs? I need a PhD student to compare the DNA in a reverted iPoc to a perfect one. Please.
Bulbils on chips can be at different places on the chips - they are usually formed at the junction between 2 of the scales and the root plate. If there are more than 2 scales, then there could be several different places along the root plate where the buds are initiated, then there could be differences in the bulbils if there is a difference in the root plate cells depending on where they are located.
As Matt mentions, plasticity may be involved. This can be a change in form of an organism not through a change in its genes, but a change in which genes are switched on or off.
What could cause this change in gene expression specifically in some kinds of snowdrops and not others? Even in some iPoc varieties, but not other iPocs?
Hmmmmm... ::)
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And another thing!
I have never had bulbils produced from an iPoc anywhere on the chip except on the root plate. On other varieties, most notably many of the yellows, I do get adventitious buds arising near the tip of a scale, and sometimes on the tops of the bulb which are cut off immediately prior to chipping. So far these have all produced perfect replicas of the parent bulb.
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Briefly web-surfing. I have got a definition of what we are observing.
"Somaclonal variation is genetic and phenotypic variation among clonally propagated plants of a single donor clone."
Discuss.
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Discuss it? I can't even say it!
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;D ;D
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Susan how did you chop your Frits?
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Hi Ann,
I understand your need for minions... and I can imagine a few PhDs might be useful... but what blessed use are pigeons, except roast? Apart from having a go at my G. Augustus, they've also been stripping my purple sprouting & pooing on it!!
Tim DH
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I think there is another process at work here.
It can’t be a ‘plasticity’ issue. If there were not some totipotent cells [able to regenerate a whole plant] you would end up missing ‘structures’. In general a meristem that is viable can produce everything [although some may only be able to make roots and some stems]. I think ‘plasticity’ explains the ‘one off’ variations that occur during the production of a single variant flower that is not repeated the next year.
I think what we are seeing here is a genetic switch issue. Modern genetics recognises both the genetic [DNA] and the epigenetic [which bits of DNA are active] as contributing to inherited component of the phenotype.
If a ‘switch’ is changed, it persists in a more or less stable way through all vegetative propagation [and sometimes through sexual propagation too]. The underlying genetic material is unchanged, but the way of expressing it is.
The more ‘juvenile’ the source of the new plant the greater the risk of a switch being changed, so it would make sense that basal plate new bulbils tend to be more stable than bulbils formed higher up the scale. It also explains why it has been such an issue in micro-propagation.
Roses [sorry] offer an example to illustrate this. Rosa ‘Iceberg’ is white. It has a burgundy coloured ‘sport’ [called ‘Burgundy Ice’] which is genetically identical, but a pigment switch has been switched. ‘Burgundy Ice’ is not completely stable and a shoot may ‘revert’ to ‘Iceberg’. It puzzled geneticists for a long time that a ‘sport’ tends to ‘revert’ back to the original form far more often than to a new form. Epigenetics explains that.
In technical terms the switches are often due to methylation of specific sections of gene associated DNA. The methylation is copied with normal cell division so the position of the switch [on or off] can persist through growth.
If ipoc forms are less stable in twin-scaling, especially in the bulbils produced from higher up the scale, it suggests that the ipoc variation may be from a single gene, and one where the switch is unstable or prone to epigenetic variation.
I think the yellowness of Lady Elphinstone is so capricious that it must be multifactorial. This year all of mine are yellow [about 15 blooms] and last year they were all green. Some years they are mixed. I can’t pin it down to maturity, weather or culture.
Chad.
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Thank you Chad, I like the sound of that. I had a feeling methylation/ gene switching was involved but didn't know why it should occur more often in some morphs than others. The single gene theory sounds plausible.
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Thinking about colour instability. Does anyone else remember cutting different coloured Hyacinths in half, tying them together and getting two coloured flowers. I Vaguely
remember doing this as a child.
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You mean cutting the hyacinth bulbs in half and tying them together, Susan?
I've never heard of that and Ian says he doesn't either. Of course we both remember growing hyacinths in those cute vases - or jam jars ( I'll let you guess who used what ) with the bulb just above the water and the roots growing in water.
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Now there is a thought. Tying together halves of 2 different genera ;-)
How closely related would they have to be to fuse together? Family fruit trees work; sort of.
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I have had a search and there is one mention of grafting hyacinth. This must be what I did. I had an unusual childhood ;) I also remember splitting stems of carnations and putting them in different coloured dyes to get multicored flowers
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'Darwin says in his book on Animals and Plants, under Domestication, Vol. 1st, page 474; that, 'the author of Des Jacinthes impressed me with the belief not only of his extensive knowledge, but of his truthfulness. He says that bulbs of blue and red hyacinths may be cut in two, and they will grow together and throw up a united stem (and this I have myself seen), with flowers of the two colors on opposite sides. But the remarkable point is, that flowers are sometimes produced with the two colors blended together'
Will have to wait til next year to try. Susan
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Thank you all for this most interesting discussion, it makes a wonderful change from eBay prices etc 8)
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I'd be VERY surprised if Darwin used the spelling ''colors'' !!
Tim DH
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Read this thread for the first time - very interesting.
Can I throw one other thought in? I have found that snowdrops immersed in fungicide or disinfectant (or both) when dormant, experience a marked check to their growth in the following growing season, then regain their normal vigour the season after. So there's a physiological effect on the bulb. Might the fungicide which is normally used during the chipping/twinscaling processes be also having some sort of physiological effect on the chips leading to instability in marking?
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The fungicide will be killing bad and beneficial fungi
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Interesting, Steve. Do you give your bulbs this treatment routinely, or just if they seem to need it?
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Anne
I was speculating about the possible effect of the routine fungiciding we are told bv the experts is an integral part of the chipping and twinscaling process. I presume their advice comes from the bitter experience of trying to chip/twinscale and seeing the chips in their bags going mouldy.
Regarding dormant bulbs, its a matter of proportion. If I have taken up a lattice pot of plants that whilst growing looked perfectly healthy, they will get knocked out and, if the tunics look good, given a quick rinse of organic disinfectant such as Citrox and repotted. If on the other hand its a single bulb of a rare and expensive variety and its got Stag big-time, I would peel the bulb layers back to what looks like clean tissue (if necessary going back to the central core of the bulb), then steeping it overnight in Armillatox or Jeyes. I replant in a high-grit mixture.
There is no doubt the bulbs hate this treatment and it severely checks their growth. But I find it usually saves the bulb.
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Steve, do you not think it might be a combination of a) the bulb being sick to start with and b) the fact that it has been severely mechanically damaged that might be responsible for the set-back you noticed, rather than the chemical treatment?
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I experimented with Citrox on bulbs moved in the green a few years ago. Although this is supposed to be a plant-safe disinfectant, bulbs soaked for any length of time would go-over a few weeks after exposure. I thought it might be harming the ability of the roots to continue to take-up water but that is just conjecture. Bulbs of a decent size recovered after a year or two.
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Steve, do you not think it might be a combination of a) the bulb being sick to start with and b) the fact that it has been severely mechanically damaged that might be responsible for the set-back you noticed, rather than the chemical treatment?
It might. The set-back occurs to bulbs not needing to be stripped back as well as the radically-treated. I haven't carried out any sort of scientific measurement. In any case I don't understand the physiological changes to the bulb that Stag is inflicting beyond the obvious (because it's so visual) physical degradation of the bulb.
I hope it is due in part to the chemical treatment, because if the bulb is capable of absorbing whatever antidote to Stag is present in the anti-fungicide steep, then it it makes it more likely that it can similarly absorb a Provado drench that will give narcissus fly and swift moth larvae a severe tummyache. "He which hath no stomach to this bulb let him depart; his passport shall be made, And crowns for convoy put into his purse;". 8)
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Anne,
Did the South Hayes revert to normal with time?
Or was the variation 'fixed'?
Chad
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In that case, the reversion has been permanent.
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Many thanks and commiserations Anne.
Chad
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I have found this discussion very useful as someone new to chipping. About five years ago I bought 'Modern Art' which was 'right' in the first year and since then has lost the green markings on the outers. I decided to chip to see if I could make it revert. Lo and behold I now have Modern Art with green markings while the original clump remains stubbornly white. Can anyone throw light on why this might be?
Barry
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Ha! I like it! Presumably the same process that made it lose the marks in the first place - I might try it with a reverted ipoc.
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>:( I am very disappointed
(https://i.imgur.com/TfjW0TG.jpg)
Galanthus South Hayes
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The thing that worries me is the assumption that either the bulbs resulting from chipping are true clones of their parent or they are so different as to be immediately identifiable as such and thus can be weeded out. Of course the chipper must be scrupulous to flower each chipped bulb so it can be verified and that manifestly doesn't always happen. But what if the bulb has been changed but only in a small way so the result is a bulb that is not quite as yellow or not quite as well-marked?
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There is a tendency to blame any instability on the chipping but I suspect some cultivars are naturally (genetically?) prone to instability whether they have been chipped or not. My 'South Hayes' (first picture) behaved perfectly normally for the first five years after purchase, then for the last 3 years has been increasingly abnormal. The first time I had a couple of abnormal flowers I assumed that they were seedling bulbs that had accidentally got in the clump so I split and isolated/labelled bulbs as normal or otherwise. This year I do not have a single normal 'South Hayes' - most of them are flowering like the one on the right in the second picture but one is virtually all white with just a small splash of green on one petal. I do not know whether my initial bulb had been chipped or not before I purchased it but you would think that if instability was actually caused by the chipping process you would see the effect in the first year or two. The plants look healthy with no streaking on the leaves that would make me suspicious that this was a viral-induced change.
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I have a number of snowdrops that I have found and grown-on for approaching 10 years. These have never been chipped by me and always come true to type. But I have given-away bulbs for chipping and last week I went to see the results in one collection. In the case of two of my nivalis ipocs the pot of chips contained one or two normal bulbs that showed no trace of the character of the original. But the rest, the majority, looked as expected. I also saw an example of a nivalis poc where the same thing had happened, another one that I had grown myself for years although I was not the source of the chipped bulb in that instance. I am sure that the person who did the chipping is scrupulously careful so these (minority case) reversions must surely have been caused by the chipping process. I know for certain that it does not happen naturally, or possibly only happens with such a small probability that I have never yet observed it. So, to the best of my knowledge, there is no inherent instability.
If there are other factors that can cause a snowdrop to 'revert' than I have never yet observed this on any snowdrop I have grown-on. But I have had one snowdrop, produced by chipping and in looks akin to 'South Hayes', that always struggled to "do its thing". I bet if you could get hold of a 'South Hayes' that was a direct, never chipped, clone of the original bulb then you would have no problems, Gail.
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Funnily enough, the few bulbs of South Hayes I still have ( though seemingly infected with virus - pinching together of leaf edges - and so kept away from others) have always flowered absolutely true, despite being chipped.
Fascinating, isn't it?
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I only met the notion that pinching together of the leaf edges is indicative of a virus a few weeks ago when I visited Avon Bulbs. How long has this been known, Anne?
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pinching together of leaf edges
1/ Could you post a picture to show this phenomenon, please.
2/ What distamce separation do you think is neccessary?
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I only met the notion that pinching together of the leaf edges is indicative of a virus a few weeks ago when I visited Avon Bulbs. How long has this been known, Anne?
It was pointed out to me a couple of years ago. I've had it from 2 sources and they have the same pinch, but I have seen others in photos which don't.
As for distance - as far as you can get. Should bin them really.
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This is what it looks like. They look fine at first as the leaves emerge, then the pinch appears as the leaves expand.
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1/ Could you post a picture to show this phenomenon, please.
2/ What distamce separation do you think is neccessary?
This is a pic of some of my South Hayes! I've never chipped my bulbs but have no idea if they had been prior to me obtaining them. Mine are all from the same stock but not all bulbs do it every year and strangely I've noticed that they're more prone to pinching on mature bulbs. Other than the leaves pinching, the plants look healthy, flower and increase well! It has never happened to any other of my drops even though they have come into contact with S H. So must be isolated to just this variety which would mean it's most likely genetic and no need to issolate. It was probably something that happened during being chipped and was passed on before it was picked up!
A real shame as it's such a lovely plant.
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Mine look the same, Shauney. I certainly can't sell them like that.
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Mine look the same, Shauney. I certainly can't sell them like that.
That demonstrates the integrity we have come to expect from you, Anne.
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The epigentic explanation would explain most of your puzzling results.
What causes epigentic methylation in the genome (what is expressed of the genome) is all kind of stress (trauma). We do stress them a lot. Twinscaling, the transplanting in the green, lack of water and what not.
This may influence the whole plant or only a few cells, like a cutting knife or a fungus attack, or virus.
But it may happen or not. It can’t be yet fully determined. Most of the outcome is certainly not visibly expressed.
Some do not grow to well, get smaller, more draught tolerant and so on. This might fade away through environment conditions or even stabilized. That’s what epigenetic expression is good for
These types which revert to their sought type under ideal conditions means the change to the wrong type was a stop of expressing the mutated genome, this part of the genome was not expressed because of methylation. This may fade after some time.
There is the other way round. The cherished form is caused by methylation of part of the genome. When it reverts it is unlikely that we find the special place for methylation again.
We even won’t find out why it happened the first place. But maybe some will do the same trick again, because the multifaceted dice of epigentic fell again to the exact side. It is more likely than a mutation, so there is hope.
But science goes on and we will find a way to understand and edit what we will. But then everything will be a piece of art.
This is probably nothing for the near future.
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The epigentic explanation would explain most of your puzzling results.
What causes epigentic methylation in the genome (what is expressed of the genome) is all kind of stress (trauma). We do stress them a lot. Twinscaling, the transplanting in the green, lack of water and what not.
This may influence the whole plant or only a few cells, like a cutting knife or a fungus attack, or virus.
But it may happen or not. It can’t be yet fully determined. Most of the outcome is certainly not visibly expressed.
Some do not grow to well, get smaller, more draught tolerant and so on. This might fade away through environment conditions or even stabilized. That’s what epigenetic expression is good for
These types which revert to their sought type under ideal conditions means the change to the wrong type was a stop of expressing the mutated genome, this part of the genome was not expressed because of methylation. This may fade after some time.
There is the other way round. The cherished form is caused by methylation of part of the genome. When it reverts it is unlikely that we find the special place for methylation again.
We even won’t find out why it happened the first place. But maybe some will do the same trick again, because the multifaceted dice of epigentic fell again to the exact side. It is more likely than a mutation, so there is hope.
But science goes on and we will find a way to understand and edit what we will. But then everything will be a piece of art.
This is probably nothing for the near future.
Hi Axel, it would be nice to have PhD students working on this interesting mystery!