Hybrid questions

[Newbiegreenthumb]

I've got a question about hybridizing orchids. When you create a hybrid, sometimes it can be used as either the seed or pollen parent. What causes a hybrid to be sterile (such as the Miltassia C.M. Fitch 'Izumi') and not produce viable seeds?

[wetfeet101b]

You can only mix & match and reuse genetic stock for recreating new hybrids up to a certain extent.
Sometimes you run into genetic dead ends such as sterile offspring. That is just how the genes play out.

This genetic dead end is sometimes desired by other sectors in the scientific community - such as a project to develop a process to cause future generations of a specific crop pest to be sterile, and thus causing the species to be eventually extinct. Such a powder keg that was.

[Ron-NY]

Sometimes ploidy also comes into play with sterility of a plant. Many times if you cross a 4N plant with a 2N plant the resulting 3N plants will not be fertile.

[Newbiegreenthumb]

Care to explain that one?

[clintdawley]

Hmm...4 N vs. 3N vs. 2N..

You know, a mule is a cross between a horse and a donkey. Horses and donkeys don't have the same number of chromosomes, so mules are sterile. This sterility is due to the fact that there is a differing number of chromosomes. Donkeys have 62 while horses have 64.

There is a chemical that can cause the usual number of orchid chromosomes to double, resulting in a plant that has twice the number of usual chromosomes; therefore 4N (a 2N plant has the normal number of chromosomes). These 4N plants are back crossed with 2N plants resulting in 3 sets of chromosomes (2N). These chromosomes can't pair up normally so a 3N plant is sterile.

[clintdawley]

...and as far as I know, 'Izumi' is not sterile. I have the plant and I don't think it's 4N

[Newbiegreenthumb]

Oh, thanks! I swear that I read somewhere that 'Izumi' was sterile. Maybe my info was wrong.