Re: example of mitotic recombination in Hosta
As one of the people who worked on the Hosta Sports Wheels, I will
answer this part of your post.
When Bob Savory first noticed 'Golden Tiara' in his seed flats it
had an edge. This is all that is recorded on the subject. Therefore it
cannot be determined whether it is a green that sported to a gold-edged
form, or a gold that sported to a green-centered form. I must admit the
first is more likely, but the second cannot be ruled out as most if not all
hosta species selections produce at least a few gold seedlings from open
pollenated seed. I have grown seed from examples of most of the recognized
species and some of the debated ones and have seen this myself. Maybe some
of the others in this discussion have as well.
I have found 300 to 500 different sports so far by searching
through nursery stock at 25 or so nurseries and various other places and I
see no reason to think that the appearance of a gold margin could be
considered the most common. From what I've seen, the appearance of white or
off-white tissue is more common and its as likely to appear in the center as
it is on the edge. The sequence that you mention does happen fairly often, I
agree, with plants that have gold tissue, but is not always the case. For
example: I found a plant of 'PeeDee Gold Flash' (which has a gold center and
a green margin) in which the L1 and L2 had become scrambled and unstable. It
produced all-green divisions, sectorial chimeras, and a green-centered form,
but no all-gold form. It is another plant that we do not know the original
In the first few years that I was hunting for sports, I found very
few streaked ones and was beginning to think they were less common than the
other types. In the years since I have found quite a few and now think that
the type of sport is pretty much random. Sectorial and mericlinal sports
often stabilise quickly within a few leaves produced in the same division,
other times no amount of new divisions seems enough to get a periclinal
form. The color of the new tissue appears to be just as random.
Regarding the #3 in your example: Is the tissue on the edge the same
tissue as the green that was previously in the center, or is it different
eg. a darker green, or a slower-growing green like the example photo I
posted last week? This would be an important consideration. If it were the
same tissue, wouldn't it be the same cause as #2----a rearrangement?
Especially if this progression happened in the same clump in adjacent
divisions? If the tissue is different from what was in the center, why would
it be different from the first mutation?
> The most common sequence in hosta sports eg in the Tiaras is
> the following: (The sequence of sports is very important for
> understanding. THat is what can be found in my booklet but is
> unfortunately missing completely in the hosta wheel data)
> Green>> yellow edge=1>> yellow =2>>> green edge= 3
> 1= a sport due to a mutation ( a very rare happening!)
> 2= a sport due to a chimeral rearrangement
> 3= a sport due to mitotic recombination.
> All this can easily be gleaned from my rule of thumbs.
> So far I have not seen a single contra argument and I should like to
> hear your explanation if you have any, for the green edge in 3
> Ps: a back mutation is as rare as a forward mutation! so is very
> Ben J.M.Zonneveld
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