Apparently repeated meristem propagation affects plant quality - how does this work?

[camille1585]

In the evening news yesterday there was an interesting segment about how orchids are growing in popularity thanks to mass production bringing the prices down over the past 2 decades. During the interview of a big commercial grower in the Netherlands, he mentioned that they are frequently in search of new genetics from the breeders in Asia. He said it was because that with each successive round of propagation (meristem propagation I presume) the quality decreases and after a certain number of years, the plant quality is poor.

I can't find more information about this though, and I'm curious to know how repeated meristeming causes a hybrid to degenerate. Anyone know?

[MrHappyRotter]

Does your evening news channel have a website? I was thinking you might be able to find a text based version of the story with more detail. Otherwise, I bet if you contacted the person that was interviewed, he'd be more than willing to clarify his position. Come back and let us know if you find out.

Cloning of an orchid in and of itself shouldn't result in any appreciable loss of quality that I'm aware of. I also did a quick search of my usual resources and didn't find anything to suggest it. I suppose there could be exceptions or he might have said that in a certain context where it's true, but I don't know of any.

With animal cloning, there are concerns about telomere length and/or age related epigenetics and mutations that come into play that can lead to degraded life span and health of cloned animals. However, life span, genetics, and the cloning techniques for orchids are significantly different from animals so I'd be surprised to find out those factors are relevant to the same degree. And based on the wording of "rounds of propagation", I really don't think this is what he would have been referring to.

If by rounds he means he's cloning a plant, then cloning one of its children, then cloning one of the children's children, and so on then maybe that would lead to a degradation of quality, but even then I'm a tad skeptical until I've seen some evidence. There's always a chance of random mutations and genetic anomalies in the cloned population, so each time you clone a clone, there's potential for a slight bit of variation from the "original". However, unless someone is consistently cloning in this manner and consistently chose a mutated clone to use for the next round, which I think would be unusual and at the very least if you know it results in loss of quality compared to other techniques you'd change the procedure, I'm not sure this is a factor either.

There are other possibilities I'm wondering about. Perhaps he misstated what he was trying to convey or explained it poorly?

For instance, traditional breeding methods can and do lead to improvements in quality and vigor over time. New species are introduced and old species are reintroduced. Breeders focus on specific traits and via luck, line breeding, and other aspects produce better quality species and hybrids that are more adaptable to cultivation. New strains are developed. Things of that nature.

So, over time, the cloned stuff remains pretty stagnant in terms of quality and vigor. However, breeding is leading to better quality, new characteristics, more vigor, etc, so it's actually leading to improvements (from a hobbyist/breeder perspective) in the orchids. The perceived loss of quality isn't explicitly from degraded quality, just the relative quality compared to the latest greatest stuff continues to decline.

[Ray]

If you clone something and are successful at replicating and achieving a nice glob of protocorms, you can divide that clump and continue growing the divisions (agitated to prevent differentiation), dividing them again and repeating that, theoretically indefinitely.

I suppose, however, there are chances of DNA replication errors with each new cell, so over time, with accumulated shifts, the resulting cells are no longer identical with the original, conceivably getting farther away with each subsequent generation.

[Paul]

Originally Posted by Ray

I suppose, however, there are chances of DNA replication errors with each new cell, so over time, with accumulated shifts, the resulting cells are no longer identical with the original, conceivably getting farther away with each subsequent generation.

This was my thought as well. Any time cells divide, mutations/errors in replication are possible. Initially, the changes may be minor and have little consequence. However, over time, as mutations/errors accumulate it is possible for a more noticeable ... and detrimental ... set of changes to develop.

[PaphMadMan]

Responsible propagators will not re-clone from cloned source plants. You can go back to an original parent plant or division time after time for fresh meristem tissue each time you want to clone and never have a problem, but multiple rounds of cloning from cloned tissue can cause problems in several ways.

In a normal plant meristem there are mutations happening at some rate all the time, but unless that one mutant cell is the one that gives rise to all the subsequent cells of that growth you will probably never see the mutation expressed. It is just a small part of the plant, perhaps not visible. In the cloning process every mutant cell that happens has a much better chance of becoming a whole plant.

Cultured cells in the cloning process are subjected to hormone treatments to force rapid cell growth and differentiation. Speeding up that process makes chromosomal abnormalities more likely, just as any job you rush through has more random errors.

Weak growing mutant cells may survive just fine in the controlled tissue culture conditions and ideal greenhouse production conditions that follow, but just not perform as well when you get the plant out in the real world. Those weak cells may never get to be a whole plant in the real world. The shoot would die and a healthy one would take over.

I'm sure there are more possibilities, but you get the idea.

[estación seca]

What PMM said. There has been discussion here of Tolumnia hybrid mericlones not true to name. Daryl Venable of Tezula Orchids said this is because some producers serially mericlone from previous mericlones. He said he buys from Jairak, who mericlones from an original division.

[camille1585]

I went to the news website and found the replay of the news segment. They interviewed the Dutch grower in English and voiced over in French.

The French voice over is saying " when you have a variery that you've been using for 10 years and that you reproduce it year after year, then the quality becomes less and less. So we go to Asia, Thailand for example, to find new genetics"

If I try very hard to listen to what the guy is saying, I hear something a bit different, but it aso seems that they cut out small portions of what he says since the french voice over text was shorter than what he said. "But what is most important is the genetics of the plant. When you have a variety from 10 years ago, and then make more and more quantities of it" /.../ (maybe a sentence missing) "So we always look in Thailand or Taiwan for the new genetic /.../" (sentence isn't finished).

I hate shoddy translating jobs....
I don't know if we'll ever be sure of what he was really trying to say. I did find the guy's email address but I'm hesitant to bother a probably very busy person (he's the director) for a silly matter. It seems like a really big company, they have 2 sites with 14000 and 25000m2 (150000 and 270000 sq ft!) of greenhouses.

[Fairorchids]

It is well known, that the first round of meristems (from the mother plant) are normally all perfect clones. And, if you repeat the process too many times, mutations are more likely to occur. For example, 1st round George King 'Serendipity' is peachy in color, while many re-cloned plants are pink.

Nurseries which do not have a mother division, will buy an inexpensive meristem, and then meristem propagate from that plant (= 2nd round).

Then, when someone forgets which is the 'original' plant, and subsequently meristems a 2nd round plant, we get 3rd round.

Etc.

By the way, not all mutations are detrimental. A local nursery purchased a bunch of C. Caudebec 'Carmela' HCC/AOS meristems. More than 10% of those plantlets turned our to be spontaneous tetraploids.

They selected the best one, had it awarded (C. Caudebec 'Linwood' AM/AOS), and subsequently meristemed that plant.

[SouthPark]

Originally Posted by camille1585

I can't find more information about this though, and I'm curious to know how repeated meristeming causes a hybrid to degenerate. Anyone know?

I recall reading from somewhere that some processes involved chemicals ..... so if chemicals are used in those processes... then it could increase chances of dna issues.

I know of at least one case where somebody has a mutant due to mericloning a mericlone ..... example here

Can clearly see it is too far different from a genuine one -- here

[Fairorchids]

The photos show two markedly different flowers, but the differences are not outside the variables that can be influenced by cultural differences (light, temperature, humidity, watering during bud development & fertilizer).

A true mericlone 'shift' is something that goes beyond these variables. A consistently different color irrespective of temperatures during bud development is one example. Such shifts are easier to identify in commercially grown populations, where you can have dozens (or hundreds) of plants, grown under identical conditions.