Mayo62 said:I've seen several mentions of tissue culture being a big no-no...
Can someone enlighten me as to why that is?
I don't worry about buying a tissue cultured (tc) daylily. Many years ago when some daylily enthusiasts complained that tissue cultured daylilies were not identical to the normal divisions I purchased about half a dozen tc daylilies and compared them to their normally vegetatively propagated plants and found no permanent differences.
When a daylily increases it does so because it produces new growing points or technically new shoot apical meristems (SAM). Each new fan has one main SAM.
In micropropagation (or commonly tissue culture) a small piece of just about any part of the daylily (usually not roots) is put into a 'soup' of nutrients and plant hormones and forced to become a new meristem. The new meristem ultimately produces a new shoot (fan) and becomes its SAM.
When the plant makes a new meristem naturally, many cells are involved and so even though some of the cells may be mutant or abnormal their effects are usually hidden. They are not always hidden - that is one way new 'sports' or mutations are found.
When a plant is micropropagated very few cells may form the new meristem and some may be abnormal. There are various reasons why some may be abnormal. Not all the abnormalities are necessarily permanent or genetic and inheritable. Abnormal plants produced by micropropagation are called somaclonal variants.
Reputable micropropagation labs use methods that reduce the chances of producing off-types (somaclonal variants) and the plantlets they produce are grown out to flowering size so that any such off-types can be removed or 'rogued'.
It has been estimated that on average from one to three percent of a batch of micropropagated plants of some species are somaclonal variants. Rarely, a cultivar of some species cannot be micropropagated successfully; no normal plantlets are produced.
Micropropagating daylilies had started by the 1980s. R. J. Griesbach wrote an article in the 1990 Daylily Journal where he stated, "The occurrence of somaclonal variants in
Hemerocallis is practically nonexistent. Among the more than 200 micropropagated plants and 27,000 flowers of 'Autumn Blaze', not a single variant was found. In commercial tissue culture propagation, variants have never been found. Because of this genetic stability, micropropagated plants are not a satisfactory source of variation."
Griesbach wanted variants so he devised a tissue culture method that produced variants in daylilies. This is what he wrote, ""We developed a tissue culture technique for inducing somaclonal variation. Of 500 tissue-cultured plants and 2500 flowers of 'Eenie Weenie', two variants were found."
One of the variants reverted back to normal; the other was stable. So, even when one tries to produce tissue culture daylily variants one manages about one in 500 plants.
If one buys a daylily at a general plant nursery and it seems different from its vegetatively produced clone the reason is not likely to be because of the tissue culturing. There are many reasons why plants that are tiny, or grown in greenhouses during the winter in the north, or have been mislabelled, etc may be different from field grown clones. Those reasons are unrelated to the tc process.
The most interesting story I learned about some of the causes of discontent when buyers purchased tissue cultured daylilies was related to 'Edge of Darkness'. My wife bought a tc version of 'Edge of Darkness even though I had a vegetatively propagated plant growing in my field. As soon as it bloomed I knew it was not 'Edge of Darkness'. It was also clear that it was not a tc problem; it simply was the wrong plant. Several years later I discussed the 'Edge of Darkness' problem with a representative from the company that marketed it. Turned out the field workers had been instructed to dig 'Edge of Darkness' from one particular end of a field but they misunderstood and dug from a different end thereby digging up a completely different cultivar. No one who purchased the tc 'Edge of Darkness' received the correct plant but it had nothing to do with tc problems. That is however, what most purchasers decided was the case, incorrectly.
