HYB: Werckmeister on Orange Pigments

Delving deep into the archives, I found the translation of Werckmeister's 
presentation at the 1963 symposium.  A few excerpts, preserving the British 
spelling of the translator, followed by my comments:


Werckmeister:  "Nearly all yellow Irises are yellow because they contain 
yellow-coloured plastids.  These plastid pigments are, chemically speaking, 
carotinoids.  Their colour ranges from Greenish lemon yellow to tomato red.  
The tomato red pigment is lycopin and, in iris, is especially concentrated in 
the beard which is then called tangerine.  Sometimes it is also found in 
orange-coloured beards, besides other carotinoids.  Therefore one cannot say 
immediately whether in orange-coloured beards lycopin is present or not.  One 
can however test this in a simple way because yellow carotinoids are soluble 
in alcohol, while lycopin is only soluble in benzol.  If one puts such iris 
beards in alcohol until all yellow components are removed, the lycopin 
remains as a pale pink tinge.  If there is no lycopin present, the cellular 
tissue will show only white."

SMc:  I have found this test to be very helpful in detecting small amounts of 
lycopene in arilbreds, especially in developing an "eye" for subtle effects 
its presence produces.  


Werckmeister:  "Whereas  the recessive gene for causing the formation of 
lycopin, must be present in a plant four times to render the effect visible 
to the eye, so-called Triplex plants in which this gene is present only three 
times, might however be possible, and might produce a little lycopin.  This 
would, of course, not be visible to the eye, the beards being orange-coloured 
like other ones.  The test, however, makes the small aount of lycopin 
visible."  

SMc:  Although this level of lycopene does not seem to be visible to the 
untrained eye, there are reports of hybridizers [even before Chuck, that is] 
who did develop the ability to spot it.


Werckmeister:  "I succeeded, for example, in obtaining some lemon yellow 
seedlings with orange-coloured beards containing a little lycopin.  The 
complete recombination would be a pink iris which at the same time would be 
recessive white.  In this matter, I was guided by the following practical 
considerations.  All dark yellow irises have a very penetrating smell.  One 
cannot have them in a viase in a sitting room.  Lemon-yellow irises, on the 
other hand, have a nice scent.  Pink and salmon coloured lycopin irises are 
similar to dark yellow ones, sometimes they have a less penetrating smell, 
but rarely a nice scent.  One can assume that there is a direct relationship 
between colour and scent." 

SMc:  I believe that Werckmeister was reporting a linkage prevalent at the 
time.  When I conducted sniff tests in the '80s, the color/smell combinations 
did not segregate so neatly.  This does suggest, however, that the fragrance 
& color may be controlled by genes on the same chromosome so that the 
fragrance of the pink parent could be used as an indicator in selecting 
seedlings that are carriers of pink.


Werckmeister:  "Yellow iris varieties show to-day much deeper yellows than 
some decades ago.  Some are nearly orange coloured.  This means that there is 
more carotinoid in the flower, which was formerly not the case. Many years 
ago, Miss Sturtevant with SHEKINAH, which was still diploid, for the first 
ime bred an iris which, in all characteristics, was a PALLIDA, but otherwise 
pure yellow.  This recomibination was considered a sensation at the Paris 
conference in 1922.  The deepening in yellow to-day tends towards orange.  It 
is probably that this is accomplished by an increase of lycopin or by the 
combination of enriched lycopin and yellow components.  Also for such 
breeding problems the test will be useful."

SMc:  Guess this answers the question about the number of plastids present, 
at least in Werckmeister's view.

Sharon McAllister

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