Re: yellow inheritance
Jim Hawes wrote:
RE:>> As for your question about how many genes control coloration in
hostas? There are more than genes on nuclei which control coloration in
hostas. Where have you been during our discussion, asleep?
Okay, I'll attempt to show that I haven't been napping.
In Drosophila Melanogaster, it has been shown that there are not one but three genes that control the expression of the trait
of red eyes. These genes are on Chromosome 1 of the four (4) possible chromosomes. These genes are in the DNA of the
nucleus. In plants, it gets more confusing because we also have DNA in the plastids, and the mitochrondria, though more
limited (averaging about 25%?). Since I'm just learning and may be prone to error, I get to ask questions for
clarification. As I understand it, the DNA from the pollen parent is SOLELY in the nucleus (i.e. no DNA from the plastids or
mitochrondia gets transferred from dad to the kids). This explains why you look to the pod parent to transfer color, because
the plastid DNA is in the egg?
The genetic controls from the pollen parent, then, are transferred to the pod parent through the plants having sex together
(I threw that in for ShayDguy). If I understand what you are saying, you believe that the DNA in the plastids controls the
all of the phenotype for color.
What Ben may be saying, and I'm not sure, is that the nuclear DNA transcribes sequences into the mRNA, etc., which ultimately
controls coloration via the chlorophyll or carotenoid content in the plastids, which are the receptors of this genetic
coding. Coloration CAN be nuclear controlled. While the plant continues to mature, there is no additional genetic material
being created that was not already in the plant from the beginning--we can't make DNA out of thin air. Some mutations may
occur, some mit rec, or more commonly, chimeral rearrangement, yet essentially all of the functioning of that plant was
prescribed to it through the original meiosis to gametophyte, to seed, to seedling propagation cycle. The "sporting" that
can occur is simply similar to the recombinations that happen routinely through meiosis and thus may be due to mitotic
The linkage mapping that I am referring to has to do with the positioning of the alleles on the Chromosome. The more distant
the alleles from the centromere, and from each other, the higher the probability of genetic crossing over. A linkage map of
these genes and their positions would be good to have. Since each Chromosome has its own linkage group, it would be really
good to discover that some researcher on the planet has already determined which chromosome controls coloration in Hosta.
I'd like to read that research, if it is available. NOW, if you (Jim Hawes) are saying that all of the coloration in Hosta
is due to the DNA content of the plastids, which never gets transferred from the pollen parent in the first place, then
I guess my question is how did the Yg alleles of of the pollen parent have their effect if not through nuclear DNA? Ben is
saying that this HAS to be nuclear and I guess I agree. What I was questioning Ben about was, "Was there a selfing control
utilized to prove that ALL of the yellows were as a result of the Yellow pollen parent"?
The occurance of Hosta Sports probably has a lot to do with the positioning of the gene loci for coloration (and other
phenotypic traits) on just a couple of chromosomes. But who knows how many genes are involved with the trait of color in the
My nomenclature is similar to what I find in other texts. I guess I don't understand what is the confusing part. I am
interested to know what labs, or scientists, have worked on mapping the bp (base-pair) sequences in Hosta. I have finally
found a resource that has flow cytometric equipment (as I had asked earlier in the winter) but I have not found others who
are actively working on the genome or proteome sequencing effort in Hosta. Most likely, because Hosta are an ornamental
plant, there is little incentive for the big labs to work on this, yet because of the commercial importance of Hosta, there
may be some valid reasons to work on the plant at this level. If A. Thaliana, why not Hosta?
So, I'm throwing out a few questions and doing my best to ask them clearly. I'm sorry if I am confusing (if you think I'M
confusing, you should read this copy of Nature magazine that I have--Yikes!), however, could you be more specific on what
part is confusing? Then maybe there would be some hope that I could clarify my statement.
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