Re: hosta-open DIGEST V1 #483
>Jim Anderson had asked a question (number 1) regarding
>similarities/differences between variegation in daylilies and
>hostas. I had declined to participate in this question because of my
>limited familiarity in daylilies.
There are very few variegated daylilies and they are mostly unstable.
A variegated seedling will show up from time to time, but they tend to
be mericlinal chimeras and few form a stable periclinal chimera.
>I summarized the concepts defined by Jones(1934) wherein chimeras
>(multicolored adjacent tissues) are a result of mutations within
>specific cells which create two or more colors within cells and
>subsequent, corresponding tissues.
I think hosta people need to get away from thinking in terms of
mutations as the cause of variegation in hostas and start looking at
the problem from a logical point of view. First, I don't know of any
other plant genera like hosta. Hostas are NOT mutating at any higher
rate then any other plants. When you look at any other plant genera
you don't see the level of variegation that you see in hosta. If
hosta variegation was due to mutations then you would see the same
level of mutations in other plants. I know the Great Ben proposes
mutations as one cause of hosta variegation and sporting, but Ben
doesn't know much about botany.
Secondly, if you propagate enough hostas you see that certain types
Variegation in hostas is most likely due to either transposable
elements or some other mechanism that turns genes on and off.
Some time ago I gave Ben a clue to figuring this out, but apparently
he doesn't know enough about higher plants and apparently doesn't have
the observational skills to figure this out, besides not knowing how
to propagate hostas. If you look at Francee in the spring you see
that the margins are lighly yellow when the new leaf is still small.
If you look at Patriot you see that the edges of new leaves are
yellow, but a deeper yellow. The leaves of Patriot have a wider edge,
the color of the center is a darker green and if you feel the leaves
they have a thicker, heavier feel to them. If you propagate enough
Francee you see this Patriot form showing up from time to time, but
sometimes not as intense as Patriot. Also, you get light green forms
from time to time. This is a POSITION effect. I'm amazed that the
Great Ben couldn't figure this out, especially considering he is
suppose to be knowledgeable about fruit flies where position effects
were first studied.
This spring I had five sports out of Whirlwind from 7 plants. Three
of the sports had leaves that were folded in half with a narrow white
center. After the 4-5th leaf the new leaves started getting flater,
but still with a thin center. Now the newest leaves are pretty much
like Whirlwind. All three plants that had this initial type of leaf
did this gradual change. This behavior is not due to mutations.
In cats calaco coloring is due to turning off of one of the X
chromosomes. Some cells have the paternal X on while other cells have
the maternal X on. When the X chromosomes get turned on/off
determines the calaco pattern you see. Streaked hostas are the calaco
cats of the hosta genus, except it's not a X/y based sex chromosome.
In a two layer histogenic structure the corpus (L2) doesn't have the
organized apical initials like the L1 layer does. Therefor, the cells
in the L2 apex can be a mosaic pattern of genes that are turned on or
off, or a position effect through a transposable element - this would
result in a streaked hosta. A streaked hosta would revert to a
"stable" edged/center variegation pattern when the cells in the apex
of the L2 layer all revert to having the transposable element at the
same location. A edged/center hosta can revert to a streaked form
when some of the transposable elements shift position resulting in a
mosaic pattern in the L2 apex.
Getting a good understanding of transposable elements is difficult.
Genetics textbooks in the 60's and 70's don't discuss them because
they were not understood well at the time, and by the 80's and 90's
genetics textbools were being written from a biochemical and molecular
biology point of view and also mostly ignore transposable elements.
For those who might want to do some searching of the literature,
search for articles by Barbara McClintock.
Now, I wonder how long it will be before I see this showing up in the
Hosta Journal as Ben's latest theory on variegation in hostas. I
certainly hope he will give me some credit!
To sign-off this list, send email to email@example.com with the
message text UNSUBSCRIBE HOSTA-OPEN