Tissue culture and mutations

[agustin franco]

Hi all:

I would like to open this discussion to present evidence for and against the hypothesis/theory that artificial plant propagation using standard Tissue culture procedures induces mutations.

We all know that in the horticultural industry, plant tissue culture is widely used. However, some plant breeders criticise this practice, because of the reasons

mentioned above. It'd be helpful if plant growers contribute to this discussion.

My first question is: is there scientific evidence to corroborate this hypothesis?

Cheers,

Gus

Edited September 15, 2011 by agustin franco

[Peter Hewitt]

I'm not sure if it is scientific, but the large slection of mutated Dionaea should be evedence that TC can indeed cause mutation.

[Zlatokrt]

I do not remember any scientific research about this, but i think that it strongly depends on the type of TC you perform. You can mix a medium with basic macro and microelements and nothing more - it will improve germination rate and more of the seedling will grow to maturity, also probably faster. But you can add a nice cocktail of hormones to support multiplication and that could increase the number of mutations. Or you can use a mutagen and that will almost surely produce some mutations.

I think that DM forms would exist without TC. Just sow 1000 seeds and you will probably see some interesting clones

Are you going to make some research in this? That would be interesting...

[Phil Green]

You can mix a medium with basic macro and microelements and nothing more - it will improve germination rate and more of the seedling will grow to maturity, also probably faster.

Invitro or sterile germination of seeds isn't really TISSUE CULTURE (TC), although I am aware a lot of people keep refereing to it as such.

[Zlatokrt]

Invitro or sterile germination of seeds isn't really TISSUE CULTURE (TC), although I am aware a lot of people keep refereing to it as such.

Interesting. Never heard of it before, but it is logical. Thank you for correcting

[John Jearrard]

There are various forms of aseptic culture which often get referred to as "tissue culture", and they have different significance in the development of mutations, however none of the systems of aseptic culture actually cause mutation.

Plant cells (and indeed animal cells) occasionally mutate. Usually this occurs in a differentiated cell that is not going to divide further, so it goes undetected. Occasionally a cell in an actively dividing meristem mutates and may then go on to develop a mutated organ, say a leaf, part of a leaf or perhaps an axilliary bud. Some of those mutations may go on to develop into complete plants.

If a shoot tip is removed and sterilised it can sometimes be established in aseptic culture. An appropriate balance of hormones in the culture medium can then stimulate rapid division. The small shoots produced can be divided, grown on and eventually form complete plants to be weaned into conventional pots. This is usually called micropropagation and is a very efficient way of producing large numbers of identical plants. Occasional cells will still mutate in this system, but because they are just a small part of a differentiated shoot, they rarely go on to produce mutant plants.

A second form of "tissue culture" is called callus culture. In this system a small section of sterilised plant tissue is manipulated using hormone treatments so that it produces a mass of undifferentiated cells, or callus. Under the right conditions this mass of jumbled cells may go on to organise into shoots and differentiated plant organs. The significant point about callus is that it is individual cells that are being cultured, not complete plant organs (there are other ways of doing this - in liquid suspension for example). Any individual cell has the ability to go on to produce an entire plant. Cell mutation ocurs in callus at the same rate as in organised plant tissues but significantly, any mutation may go on to produce a mutant plant. This is the effect that appears to produce mutants from "tissue culture". In fact, it is simply that the normal rate of mutation among plant cells can result in entire plants in callus culture, which is unlikely in micropropagation.

Commercially, labs try to avoid callus culture because they want to produce large numbers of identical plants, and so stick with micropropagation.

Breeders commonly use callus and cell cultures as a way of producing potential variety. Often well established cultivars are put into cell culture in the hope of developing a slight improvement while maintaining the basic qualities of a cultivar.

With Dionaea, and some other CP, there is an issue that they produce callus very easily at the site of a wound, and can regenerate plantlets from that callus. Under aseptic conditions the distinction between micropropagation and callus culture is not always clear.

Obviously Darwinian selection occurs in cell culture. Those cell lines that are most vigorous tend to out-compete the weaker cells, however the cells that are strongest and most vigorous as a cell culture may not be the mutations that form the strongest and most vigorous differentiated plants in compost. The selection pressures are different in the two environments. There are a number of dwarf cultivars and cultivars with physical distortions to the trap that are no longer functional that were clearly vigorous cell lines, but make weak plants.

Does that help at all?

Edited September 16, 2011 by John Jearrard

[moof]

Large numbers of plant cells divide at a high rate in TC cultures; more divisions in a short period of time makes a mutation likely to occur.

Peter

[will9]

Robert Wellens Tc culture in the Netherlands is the only in the world that can make variegated plants from normal in TC culture,he can make also very different looking plants from one normall plant only whit the mix he used ,he can manipulate the plants like he want to.so it s possible .

Hes not cultivate CP but many other plants .I supoose it s work the same way whit CP.

Allways very intresting to visit this nursery and talk whit him,

Cheers Will

[agustin franco]

Hi all:

Thanks for your answers. I think some of you have answered the question. It's possible to induce mutations in tissue culture, as long as, the conditions are artificially created for this event to occur. Of course, a novice in the area, may inadvertently induce mutations, by adding too much hormones or specific chemicals.

However, the point i would like to discuss is whether plant propagation in TC without any deliberate or accidental intervention induces mutation?.

I believe the answer to be NO, but i may be wrong.

Thank again

Gus

[moof]

The percent rate of mutations would be the same I guess; but with a lot more plant obtained in TC, it is likely to find a mutated plant in a shorter period of time. It's like target shooting - in TC you've got hundreds of plants (missiles) and there's a bigger chance to find a mutated one (shoot the target).

Peter