beckygardener said:I must confess that I really don't understand what happens to the genetics of a tet or dip conversion. There is a possibility that the seedlings might produce the opposite if the conversion reverts back? It's a concept that seems to complicate my hybridizing because it goes beyond my scope of understanding. If the genes were to convert back, does that mean the seedling would be a sterile daylily? Sterile pollen AND pod? Or does that mean it would be "opposite" fertile? ("Opposite" meaning if it was a tet conversion and reverted back, it would be a dip ..... or a dip conversion reverting back to a tet.)
And what genetic traits would such conversions carry? If a tet conversion, would the genetics still contain the dip pedigree? Or would those dip genetic traits end when converted to tet (... or a reverse conversion of a tet to a dip)?
A tetraploid conversion is a daylily that has been treated with a chemical or another agent to make its chromosomes double or be twice as many. As an example, lets say I have hybridized a diploid daylily called 'Red Wonder'. I register it and I consider it to be a break-through in reds. I think I would like to have the same break-through in tetraploids so I decide to convert the diploid 'Red Wonder' into a tetraploid. Then I can use it in crosses with tetraploids.
There is no simple way for a daylily hybridizer to convert a registered tetraploid daylily cultivar into a diploid - there are no diploid conversions.
In a diploid daylily every cell, of millions of cells, is diploid. In a tetraploid daylily every cell, of millions of cells, is tetraploid. When I treat a diploid daylily with one of the chemicals to make its cells tetraploid I may not be able to make all its cells tetraploid (or sometimes I might be extremely lucky and all the cells become tetraploid). I may be lucky enough that some of the important cells, those that make pollen usually, do become tetraploid. If that is the case then I can use the tetraploid conversion (as the pollen parent) in crosses with normal tetraploids and the end result will be the same as if I had a version of 'Red Wonder' that was completely tetraploid.
If the converted 'Red Wonder' plant reverted back to being completely diploid then it would become the same as the original normal, untreated and unconverted diploid 'Red Wonder' plant. [More or less, we will not worry about whether the chemicals that the plant was treated with might have changed anything in the reverted plant.]
The only kinds of tetraploids that can revert back are treated diploids (or their divisions) sold as 'converted tetraploid' versions. One would have to specifically buy a converted plant, (identified as such by the seller) presumably to use in crosses with normal tetraploids.
One can find the AHS daylily dictionary of conversion at
http://www.daylilies.org/ahs_d...
Tetraploid conversions are genetically the same as their diploid versions and carry the same genetics and characteristics. There are some physical (and related) characteristics that change because tetraploids have larger cells than diploids do, etc.
It is theoretically possible to try to convert a normal tetraploid (4N) daylily to an octoploid (8N). That would mean trying to change it from having four sets of chromosomes to having eight sets. One can also theoretically try to convert a normal triploid (3N) daylily into a hexaploid (6N) daylily. That would mean trying to convert a daylily with three sets of chromosomes into one with six sets.
