Re: Anthocyanin Pigment Inheritence
In response to queries re glaciatas.
There is basically three genetic lines to remove anthocyanin. That is
three sets of genes that have been used in iris. To produce
anthocyanin, particularly delphinidin, there is about 22 biochemical
steps in the production. Blocking any of these will stop the
production of anthocyanin. These are called structural genes. In
addition you can have control genes that prevent certain genes from
acting or by themselves remove anathocyanin.
But lets focus on what we know.
There is recessive reduction of anthocyain, This used to be called
recessive white and the symbol used was "w" and blues were "W". But
this is incorrect as yellows, pinks, and oranges etc all can exsist
with four sets of "w", ie w/w/w/w genotypes. One of this type crossed
with a flower with anthocyanin produces all anthocyanin flowers , as
long as no recessives were carried by the anthocyanin flower (brown.
ed. purple, blue etc)
There is the dominant reduction of anthocyanin , labelled "I" and we
can use this symbol. This is the commonest gene used to produce pinks,
yellows oranges, apricots etc. A cross of one of these (having one
dosage of I ) to a flower having anthocyanin (ignoring all recessives
present) will produce half flowers with anthocuyanin and half without.
Not the use of the term "reduction", not removal. Multiple dosages of I
will probaly reduce anthocyanin even more.
Plicata genetics are complicated. Basically a plicata is a plant having
four plicata genes, selecting from the three known alleles. Luminata,
glaciata and luminata. A plicata can also have other genes such as I
or wwww, removing anthocyanin. Thus we get a plicata such as Laced
Cotton. There is nothing in definition of plicata genotype
indicating it has to have anthocyanin or any fixed pattern of
distribution. Known patterns include classic plicata, luminata,
luminata-plicata, zonal and glaciata. We don't know what the pattern is
when a glaciata has four luminata genes. It had been assumed for a
long time that luminata pttern had four luminata genes but this is not
so. Also any of these patterns can also have an I gene and we can get
a plicata pattern in cartenoid pigments with a plicata distribution.
Now called a yellow plicata
The glaciata , which is four sets of the plicata glaciata gene , also
has no anthocyanin. The removal of anthocyanin this way produces an
exceptional clean flower. But an exceptionally clean flower is not
necessarily a glaciata.
A glaciata flower crossed with a wwww will produce all offspring with
anthrocyanin. For example a white glaciata X recessive white, produces
all blue offspring.
The glaciata is a recessive of a recessive (plicata) and has absolutely
no effect on pigment unless paired up as one of four plicata genes.
And only shows glaciata when in a set of four glaciata genes. So is of
no interest unless you are working plicatas. Of course working a line
of glaciatas to produce exceptionally clean non anthocyanin flowers is
a possibility, except that glaciata plants are weak, have poor
branching and usually not great flowers. But these are not all minor
problems. There are now stronger and better formed SDB and IB
glaciatas and eventually perhaps also with TB, but not so far. All TB
glaciatas I have grown here have quickly disappeared.
The proper test to see if a plant is a glaciata is to cross with a
plicata. All seedlings will be plicata if it is a glaciata. Of course
some of thes plicata could be glaciatas.
It actually it is even more complicated, but no further information for
this post, I sure it is confusing enough as is.
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