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RE:Subject: Analysis of MV's sedlings absence ofabsence of carotene and anthocyanin in #9

  • Subject: [iris-photos] RE:Subject: Analysis of MV's sedlings absence ofabsence of carotene and anthocyanin in #9
  • From: irischapman@netscape.net
  • Date: Mon, 17 Jan 2005 12:24:45 -0500

Some information here to help us with an analysis. The distribution of 
factors such as intensity of yellow or can be viewed as continuous or 
discreet. Discrete can be in steps. Look at the heights of bearded iris, all 
types from pumila to the tall TBs at 40"+. This forms a continuum and 
plotting on a graph with height being the horizontal axis and the number at 
each height being the vertical axis , we would end up with a curve. 

Most factors in nature have what is called a normal distribution of variance. 
That is all the various small factors making up an item cause a variation. 
The more factors the narrower the curve, the more factors the wider the 

We know that we have several different classifications of height/type 
classifications of bearded iris EG: MDB, SDB, IB, BB, TB etc. If this was 
only a discrete difference then all MDB would be 6", all SDB 12" etc. This is 
obviously not the case. The plot of height versus distribution would give us 
several peaks. One for each median (average) height for that class. Thatr is 
there would be a peak for MDB, for SDB IB, TB and minor peaks for MTB and BB 
(not as many varieties and numbers count). Thus we are dealing with both 
discrete and continuous. Genetically MDB, SDB, IB and TB are different. They 
all have different sets of genes. The Iris pumila has four sets of 8 genes 
8/8/8/8 and in crosses with TB 12/12/12/12 have produced MDB 8/8/8/12, SDB 
8/8/12/12, IB 8/12/12/12. each one of these types could produce their own 
normal distribution curves ( I'm ignoring judging and registration rules here 
and focusing on genetic classification) that are very smooth without any sub 
peaks or any skewing (more on one side of the median(average) then the 
other). Thus if we didn't know the genetics (or have the parentage) we would 
have to classify an unknown into a category based on its height ( for the 
moment I'm ignoring the other information I might have). Thus an iris 16"in 
height would be classified into SDB even if it is IB genetically, just on the 
lower end of its scale. An SDB that is 7" tall would be classified as an MDB 
even if it is genetically an SDB. If we had the parentage we would be able to 
more accurately assess what it is genetically.

The same principals apply to dissecting a cross with as much variance as this 
one. When it comes to analysing the category we place something in both 
factors have to be considered. FoF  would seem to be tttt, but is more 
apricot-yellow then pink. We use this knowledge to place seedling #4 into 
tttt  category , although other interpretations are possible.

The same with looking at the amount of yellow and amount of blue in each 
The removal of anthocyanin is referred to either Dominant reduction of 
anthocyanin ( not referred to a complete removal of anthocyanin) referred to 
as "I", or recessive removal of anthocyanin .  To tell which, (dominant or 
recessive) look at parents and look at the seedlings, trying to ignore other 
factors, and keep in mind what else may mask the factor we are looking at.

The yellow is more complicated as Robin noted.  I have some evidence that the 
cream (flavanoid pigments) and beta-carotene and alpha-carotene may act 
independently and may be what is referred to as y1, y2, y3. 

With anthocyanin there is about 20 steps in production of anthocyanin from 
its colourless precursors into the visible form. This is like a garden hose 
with 20 shut off valves in it. If any one is turned off, the water 
(anthocyanin) doesn't come out the other end. In various plants about 8 of 
these steps have been blocked. In iris there are several, more then 3 and 
less then 6, that can turn off production.

With the yellows, the cream flavanoid seems to be completely independent from 
the other yellows, no shared precursor, a different chemical chain.

With the carotenoids it is like we have one garden hose coming from the tap 
with  a "Y" junction at some point ( chemical biosynthesis info, not just 
observation). Now put at least one tap in each line. Thus you can cut off the 
main tap, no beta or alpha carotene. You can turn one of the "Y" branch taps  
and remove either apha or beta-carotene or you can turn both off at the y 
branches to remove both, the same as turning off the main tap.

I hope this helps but I'm afraid it may confuse everyone.  I don't have any 
pictures of normal distributions curves handy to post , other wise I would.

Chuck Chapman

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