Tissue culture.

I hope there are no objections if I make the attempt to explain the 
difference between the two different teqniqics for tissue culturing 
Daylilies?

The old way-that caused so much trouble, is called CALLUS culture.  It 
involved the formation of undifferentiated cells, that is cells that did not 
make up any specific tissue.  The process was simple, just mash up the tissue 
and grow them in a bath of nutrients. Since plant cells have the ability to 
grow into entire plants under the right hormonal influences, it was easy to 
make thousands of cells in a short time period.

The problem was that the cells of Daylilies are not always stable. Since it 
only took one cell to produce a plant or for more callus tissue-if the grower 
picked the wrong cell-then all the subsequent plants produced from that cell 
or the callus line, produced from that cell, would be off.

The other way to do the tissue culturing involves a process called SHOOT TIP 
proliferation.  This involves removing the growing tip of the plant and 
putting it on a plate of nutrient agar.  Again the hormone levels determine 
what the shoot tip will do, under one ratio the tips will produce more shoots 
and those shoots can be pulled apart and more shoots again produced.  Once 
you have the number of shoots you need that corresponds to the number plants 
you need, the shoots are moved to a medium with a different hormone ratio 
that causes the shoots to grow roots. Once the roots are large enough to 
sustain the plants they are moved to a pot and put in a green house to harden 
off and grow.  Then they are put out side in rows and allowed to flower.  Any 
plants that aren't "correct" are them weeded out.

Because shoot tip growth involves specialized tissue called meristems and not 
single cells, the plants produced are not so subject to changing.  Really 
what is happening is that the shoot tips grow just as any normal plant would. 
 Since all plant grow occurs from the meristem tissues thus its the same as 
making a cutting and rooting it. 

I am tired and its bed time- I hope that this is clear.

Paul

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