Re:HYB: another blend (photo posted

The number of "t" alleles in Immortality is not necessarily 2. It does produce offspring with 4 "t" alleles such as Midsummer Eve. The way alleles work in gametes is a bit complicated as outlined by Kidd in his articles on tetraploid inheritance which he summarised in "World Of Iris" on pg 394-397. Basically, the gene divides before the alleles are chosen for the gametes (reproductive cells, eggs and pollen). Thus you can consider that the two genes each parent contribute are more like choosing two from a set of eight. In the situation where there is only one t and three T alleles, after division, there are two t alleles in a population of 8, 6 of which are T. Thus gametes can be formed with two t alleles even if there is only one out of four alleles in the parent. The farther the allele is located from the kinetochore (central point) on a chromosome, the more likely this will occur. Thus with just one "t" there can be as many as one out of 24 gametes with two "t" alleles. ( use table on pg 395 in WoI) and with two "t"alleles in one parent there can be as many as 2/9 th of the gametes with two "t" alleles. Thus to really determine the number of t alleles in Immortality it would need a number of crosses with good statistical analysis. Personally I suspect that Immortality is tTTT, based on records of offspring listed in online database.
In the seedling I see no indication of there being either 3 or 4 "t" genes. The beard is dark yellow in the throat, but definitely not tangerine orange. When I see seedlings with three "t" genes I see a darker yellow with more orange in it and far more of the beard coloured. It is still possible that the seedling has 3 "t" genes, but I doubt it. The "pink" in the falls are a blending of a slight anthocyanin wash with a light yellow, not tangerine. This "pink"is more of a pallida pink rather then a tangerine pink.
Basically this seedling is an amoena with a light anthocyanin wash on a light yellow ground.
Doing a little background research shows that one grandparent of Immortality is Cross Stitch, an amoena plicata. The dominant amoena gene and dominant reduction of anthocyanin gene operate independly. While the amoena gene controls the anthocyanin so it occurs in the falls and not the standards (or at least reduced amount in standards) it only distributes anthocyanin when anthocyanin is present. The dominant reduction of anthocyanin gene prevents anthocyanin from being present. Thus a white iris, such as Immortality can have the dominant amoena gene but not show it as it also has the dominant reduction of anthocyanin (DRA) gene.
It took a bit of doing to find a picture of Pinafore Pink (Schreiners 1978) but I found one in an old Schreiner's catalogue. To my eye I see a faint dusting of anthocyanin which produces a darker or more bluish toned pink. This is common in the older pinks from this era. While the DRA gene reduces the anthocyanin present it doesn't completely remove it. With several dosages of the DRA gene the removal of anthocyanin is more complete and the colours of whites, yellows, pinks etc are less muddy and more intense or purer. With many (if not most) of these modern cultivars (white, yellow, pinks, oranges etc) there are several DRA genes present and we can see crosses of yellow X yellow, pink x pink etc which produce all the seedlings of the same colour. There still are some of these type of crosses which produce a seedling(s) with anthocyanin but a closer look at one (or both) of the parents show a faint anthocyanin wash, particularly when it first opens and more so on a cloudy day. With an increased amount of anthocyanin it would likely cover more of the falls and perhaps leave no yellow rim.

In any case the light anthocyanin is present in Immortality, which is a faint lavender amoena when it first opens. It would seem possible that both Pinafore Pink and Immortality have three dosages of DRA and the seedling has two dosages. While the anthocyanin present may be an expression of the umbrata patten, it lacks the sharpness of distribution associated with this pattern and seems to be more of a light wash that doesn't completely cover the falls. Much like the light anthocyanin seen on Immortality when it first opens on a cloudy day.

The presence of yellow is dominant over non-yellow. A pink iris is essentially a yellow with the production of yellow blocked by four dosages of "t" so the biochemical conversion of lycopene to beta-carotene is blocked. Thus a pink x white produces yellow flowers (as long as all anthocyanin is blocked). If it is a white with a red/pink beard, then the seedlings would be pink, as the white with red beard has four sets of "t"genes. White iris have four sets of recessive genes that block production of carotenoids ( as well as the appropriate set of gene that block anthocyanin). Thus the number of yellows from a cross of pink x white could be up to 100%. (depends on recessive genes present in coloured parent).
There are considered to be three basic types of yellow. This probably corresponds to beta and alpha carotene with the third being perhaps the flavanoid yellow which is under control of a different set of genes. There also is the yellow which is present in orange and in yellow iris with red beard. This yellow is recessive, needing four sets of genes to produce it, not just one as with the regular yellow. The production of beta as versus alpha carotene is not known.
There may be a dosage level of cartenoid production depending on the number of Y genes present. The intensity level may be under control of another set of genes such as the production of "bacterial phytoene synthase"( see article on "The Red Iris Project" by Rick Enst in July Bulletin and in Fall "Tall Talk") that increases amount of chemical that is precursor of lycopene and increased dosages result in more lycopene and carotene when there is no blockage to carotene production. All of these factors can control shading of yellow and intensity.

The production of cartenoid amoenas is quite complicated and seems to be under control of at least two different genes. To my thinking it seems to be the recessive inhibition of anthocyanin in the standards plus a separate gene factor that added to this prevents the presence of cartenoid pigments as well in the standards. These factors don't seem to be present in this seedling.
Thus this seedling will not produce any pink amoenas. It will produce pinks when crossed with pinks, at least 2/9th . At least half of them will have an anthocyanina wash.

You can do an extraction on the flower bud or collapsed frost damaged flower. Since the main concern is the prescence or absence of anthocyanin a simple water extraction can be done.

Chuck Chapman



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