Yellow, altho Brave Hosta Scholars,
A careful review of the hosta literature will reveal that there are
generally two different kinds of yellow hostas, using their genetic
characteristics to determine their differences. Dr. Kevin Vaughn in
the AHS Bulletin 11 article, Chloroplast Mutants in Hosta, mentioned
"aurea" as the first identified type. He reported that Yasui (1929)
found that all of the plastid mutations in variants of the H. sieboldii
to be maternally inherited and probably controlled by plastogenes. The
work of Dermen, Stewart and others in histology of Layers I, II and III
within meristems and in leaves of more mature plants, showed that a
genetic analysis of self pollinated progeny of chimeras is able to give
information on the types of inheritance involved, i..e.under control of
plastogenes or nuclear genes.
Hosta clones containing aurea mutant plastids are chartreuse or yellow
shades which are distinctively different from the normal green color of
most hosta leaves.Seedlings from these clones, when self pollinated or
when used as pod parents in crosses are always aurea types. It was
determined that since ovules inside pods are always formed by LII, a
plastid mutation in this layer will result in all mutant seedlings when
the pod patent is selfed. Segregation of plastid types suggest that the
site of genetic control for most of these plastid mutants is in the
plastid itself according to studies of Tilney-Bassett( 1975). Snow Flake
mutant plastids appear to be the exception to this generalization, since
they possess a Mendelian recessive characteristic.
Woods and Dubuy (1946), Yasui (1929) and Vaughn(1980) all noted seasonal
"greening up" of the mutant areas in some hosta clones while von
Wettstein ( ), showed that in other genera than hosta, white or
yellow color of leaves appeared upon exposure to light. "August Moon
was considered by Vaughn to be of the aurea mutant type as listed in his
famous Table 1 data. Vaughn in his article in Bulletin 11, "Variegation
in Hostas" stated that all yellow hosta behave in a manner similar to
the yellow centered forms. Why? you may ask?. Because of the maternal
inheritance of yellow plastids which exist in the LII.
As stated previously, in Bulletin 11, Vaughn identifies "August Moon as
possessing the aurea type mutant plastid. As an exception to the
maternal mode of inheritance, Vaughn also identifies 'August Moon' as
being heterozygous for a lethal factor. This description may seem
confusing to some because it is also called a codominant nuclear
mutation by others. When the genotype is heterozygous (Yy) the phenotype
is normal yellow; when homozygous recessive (yy), the phenotype is
normal green: and when homozygous dominant ( YY), the plants die usually
in the seedling stage because of the lethal factor present. I will not
take it upon myself to explain the relationship between the codominat
nuclear mutations that are possible and Ben Zonneveld's theory of
mitotic recombination as a causal factor for variegation in Hosta
(especially the green edge on a yellow background leaf. This is his
responsibility if he wishes to defend his theory).
Finally a brief summary to describe Vaughn's work with the Electron
Microscope. In Bulletin 13 he describes several morphological changes
that occur in plastids. As a hosta grows and its leaves expand,
plastids of yellow clones are observed not to consist of stacks of
thyllakoids as the green chloroplasts are arranged , but rather yellow
colored plastids may take on a dilated shape and become dispersed within
the cell. Thus, they become more efficient in performing their
photosynthesis function .In the case of colorless leucoplasts, they
"explode" and take on a characteristic shape with some being whiter than
others. Serving as a scientific reporter of events, not a researcher, I
have attempted to describe some of these attributes of plastids in "
Those Blastid Plastids" in a recent Journal. It may be boring reading
because the plot is terrible. But it may be of interest to those hosta
nerds addicted to the need to know about plastids.
Where are we going in this discussion? We are going to the very center
of the plot which can be summarized in the following axiom....."
twinspots, into a green edge on a yellow leaf, do not grow!" Will you
repeat the axiom, you ask? ..............Yes, I will.
" Twinspots, into a green edge on a yellow leaf, do not grow" . This
axiom, no matter how clumsily written, is still a good conclusion of
our debate on the origin of sports. We have heard over and over on
hosta- open and elsewhere that "mit rec" is proof that Ben's Rule of
Thumb is accurate. Mit rec is genetic jargon for mitotic recombination,
, a process that may occur in plants. It is up to the person promoting
this theory to explain how the process works. This has not been done.
Nor is there any experimental data to prove the theory. Nor has anyone
shown how two spots on a yellow hosta leaf develop into a green margin,
as claimed in Ben's Rule of Thumb.
What do we do now? We exclaim that the theory has not been proven. Then
we take our Booklet of Sports and mark out all errors with a black
marker. Better yet, we can eliminate the entire Rule of Thumb because
two thirds of it is incorrest and other thirds which should have been
included , (mutant plastids and their sorting-out processes), are being
considered as invalid by Ben.
Sorry, Ben. This is what happens when you guess and are wrong in your
guesses. It is embarrassing to admit it when you are wrong. That is why
I am helping you out and doing it for you.
Have a nice day!
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