Re: Re: Iris attica (was more questions from the newbie)

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Laurie;

 

            I always recommend trying any cross you are curious about. Many times they won?t work even when they should and sometimes they work when they shouldn?t. But if you don?t like wasting energy on futile attempts here is a simple genetics lesson.

            Chromosomes occur in normal somatic cells in pairs. Whenever one of the chromosomes lacks a pair it tends to make future reproduction difficult. Pumila is tetraploid, it has four sets of chromosomes in which there are 8 kinds. 8x4=32 chromosomes. Attica has similar sets of 8 but only 2 sets, it is diploud, 8x2=16. Each gives one of each pair to its pollen or egg. Pumila (16) and Attica(8). The resulting cross is sterile. 8 of pumilas chromosomes match up with 8 of atticas but the other set of 8 from pumila have nothing to match up with. Remember I said any unpaired chromosomes will tend to cause sterile offspring. The more unpaired chromosomes the more likely this is.  Pumila should cross with attica, but the resulting offspring will be sterile.  In theory all bearded Irises will give at least one generation, but whether you can go on from there is problematic, and that is where the chromosomes being balanced are important.

            Whether or not you can get a first generation has less to do with chromosomes and more to do with other factors such as pollen tube growth, and things we may not understand. In theory plants within a major group within Iris, should all cross with each other. It is probably more interesting as to why they don?t, than that they do. I hope this makes sense.

lfandjg <laurief@paulbunyan.net> wrote:

--- In iris-species@yahoogroups.com, "lfandjg" <laurief@p...> wrote:
>Sibtosa works, but attica X pumila doesn't?

HAH!  Funny I should have used that particular example in my earlier
post.  I just checked on my toilet tank seeds, and what should I find
but one of the pumila seeds sprouted!  That gives me germination in
three of the SIGNA seedlots I purchased this year so far:  4 out of 4
yellow attica seeds, 1 out of 4 violet attica seeds, and 1 out of 6
pumila seeds - all germinated after having been soaking in the toilet
tank since 1/19.

I apologize if these updates are boring you guys, but this is all just
too exciting for a first time iris seed-starter with a bad case of
cabin fever here in northern MN with a good many weeks of winter still
ahead.

Laurie