RE: Pollen
- To: "'hosta-open@mallorn.com'" <hosta-open@mallorn.com>
- Subject: RE: Pollen
- From: R* G* <r*@centrelab.com>
- Date: Tue, 6 Jul 1999 10:35:17 -0400
Beth,
Ventricosa pollen WILL work. Apomixis is a seed-parent phenomenon.
External pollen will NOT fertilize ventricosa. Ventricosa pollen WILL work
on other species.
Remember that ventricosa is a tetraploid. Hybrids using ventricosa pollen
are likely to be sterile, since most of the varieties out there are diploid,
not tetraploid. Diploid x tetraploid = triploid. Let me re-phrase that.
Remember that ventricosa has 4 sets of chromosomes. Hybrids using
ventricosa pollen are likely to be sterile, since most of the varieties out
there have 2 sets of chromosomes, not 4 sets. [2 sets] by [4 sets] = [3
sets]. The plant cannot divide 3 sets of chromosomes into 2 equal parts, so
triploids are generally both pollen- and seed-sterile.
It is a matter of discussion whether apomixis in ventricosa RESULTED from
tetraploidy, or if tetraploidy RESULTED from apomixis.
Oh, and just to make things a little more complex, most apomictic species
will make SOME (and some is a very very very low percentage) sexual seed.
In other words, if you make 100s of crosses onto ventricosa, and grow out
10,000s of seedlings, you MIGHT find an occasional seedling that resulted
from cross-fertilization, and not apomixis. Apomixis is not a perfect
system.
Rick Grazzini
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