AR: Aril Traits

Message text written by Walter Moores:

>Thanks, Sharon, for this list of aril traits.

        Tell us what you think of the virus markings.  Some years, 
these seem more evident on the quarters and halves, and other 
years they are hardly there.

        Are virus markings a minus?
<

There was so much disagreement about "virus" markings that the committee
sidestepped the subject entirely and it still hasn't been resolved.  Some
think the splotches are an attractive aril trait.  Some call them an
undesirable aril trait.  Many of us aren't sure that they are an aril trait
at all.  [If this WERE an aril trait, I'd expect it to be found more
prominently in arils than in arilbreds so I don't "count" it in seedling
evaluation.]

These markings are, of course, a minus on the show bench if the cultivar in
question is NOT supposed to be splotched.  

This is certainly not the virus described in Garden Irises and TWOI,
because that one affects the foliage and the overall health of the plant. 
Splotched flowers can appear on arilbreds that have extemely vigorous,
healthy plants.  About 20 to 25 years ago, some hybridizers were attempting
to trace where the identification of this trait as a virus had come from.  
The most common explanation turned out to be the resemblance to Rembrandt
Tulips -- a pattern that had been attributed to a virus.  

So the next logical step seemed to be a test for virus.  For the type of
virus that affects the foliage, it had already been proven that meristem
culture could produce virus-free stock.  Doing this for cultivars that had
splotched flowers should produce splotch-free stock, if the cause were
indeed a virus.  As far as I know, however, they were never able to obtain
such evidence.

>       The picture of MOHR PRETENDER that appears from time to 
time in the Schreiner catalog shows it to be free of virus markings.
But, as I grow it, there are many virus markings.  Do we attribute 
this to climate, soil?
<

In my experience, climate, soil, culture, and weather all play a part. 
Some cultivars produce flowers that range from completely clear to heavily
splotched from the same clump over the course of the bloom season.  From
dissecting flowers, I'd say that the splotches form fairly late in the
flowers' development.  I suspect that heat may be a trigger -- but hasten
to add that I have no proof of that. 

It is definitely related to the flower's pattern.  Solid ground colors are
prone to splotch while veined patterns are not.  I've grown splotched &
non-splotched together for years without the splotched trait appearing in
the non-splotched types.  All of which leads me to believe that the
explanation is not as simple as a viral infection. 

>       How can you tell if a splotch of contrasting color is a virus 
marking or part of the usual color for a cultivar?

        Are these markings kin to 'broken color/variegated' markings as 
in Ensminger things?
<

The markings usually attributed to virus are quite different from the
broken colors.  

In the former, something happens to the colorless anthocyanidin precursors
that make them develop into visible pigments in certain areas.  A light
lavender self with dark signal might thus appear a purple-splotched
lavender -- but the ground color would be true and it would still have its
dark signal.  A  yellow might develop purple flecks, but between those
flecks the color would be true.  

In the broken-color pattern however, something interferes with distribution
of the pigments which results in lighter patches on the flower.  This is
NOT restricted to the anthocyanidins.

I'm convinced that these are two different mechanisms because I've had a
number of seedlings that show both traits, resulting in a splatterpaint
effect in white, yellow, violet & brown.  Something you pretty much have to
see to believe....

Sharon McAllister
73372.1745@compuserve.com

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