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. 

Chuck Chapman

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