Re: 'Swerti' spelling

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Dr. Dan's information on production of pigments, anthocyanin and carotenoid, from a genetic and biochemistry pathways is excellent. But his application of this knowledge to iris is weak and unfortunately contains a lot of errors. And a lot of his references are not supportive of the conclusions he has drawn from them.

Well all iris can eventually all trace back to a common ancestor at some point, the connection between I. pallida and I. variegata to a common squalens ancestor is a speculation that lacks any supportive evidence. The evidence against it is that the sualens pattern is not one that attracts insects, where as the other pasterns have their role. Each flowering plant  has evolved it's colour and pattern to attract specific insects for their role in  pollinating flowers. The mixed colour flowers, such as squalens pattern, are accidents of crossing of related species. They don't have colour or pattern to attract insects, so would be an evolutionary dead end. So couldn't exsist as a vaible parent species.

While transposons do play a role in broken colour iris, there is no supportive evidence that plicata pattern per se is a transposon. There are many flower patterns in various species that are not transposon caused. Other examples other then "plicata" are spots on lilies, picotee on various flowers, patterns on orchids etc. etc. These are all consistently inherited patterns that are Mendelian in their inheritance. Transposons are non Mendelian by their very nature. Especially the active transposons.

For further reading for anyone I would suggest "Mobile DNA II" ed Craig et al 2002, and "Plant Transposable elements" ed by Nelson 1987. There are many other good books and articles on this, but these two books happen to be on my desk, so references are close at hand. Other factors playing a role in _expression_ of colour are gene silencing particularly by what are referred to as "epigenetic " factors. A reference for this is "Plant Epigenetics" ed by Meyers 2005. Another book currently on my desk.

By the way, with Ac/Ds gene pairs in transposons, they can be on different chromosomes, but also can be on same chromosome. I have found strong evidence of this with the speckled pattern in Daylilies. It may also be located on same chromosome in broken colour iris.

The reactivation of a silent transposon is usually by the inheritance of a gene producing the Activator (Ac) transposase gene from a different parent. Once silenced it is rare for it to be reactivated other then by this means.
 
Various species contain genes that are now considered to be part of "plicata" gene complex. The stripping  as found in I. variegata, the  recessive white known as "glaciata"  is found in many  species. the gene called "luminata'  is also found in many species. They all play their own role in species of origin. When these are combined in same "complex" ( with at least two other  plants genes), then we get plicata pattern. It is  the recombination  from various species which gives us" plicata complex" as we know it in bearded iris. This "plicata complex"  doesn't appear to be  any single species of iris.

As to "Plicata" pattern in iris, there so far is no evidence of it in any species collected in wild. So far the closest we have is the cultivar "Iris sweertii" and evidence so far is that it was named from a garden specimen, not from a collected plant in a population. Iris plicata is similarly a collected plant in a garden, not collected in wild (as far as what  ai can tell).  Based on my research into this, if there is a population of "plicata" iris they should be found in region between where we find I variagate regina (north Greece) and where Kupari was collected in Bosnia.

These are regions which are not very far from each other ( about 100-200 miles) and very well could have overlapped in recent geological time.

Chuck Chapman


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