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
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.
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