Re: HYB: Rebloom Inheritance

Hello list,

 

I'm chiming in a bit late from the shadows here, but Francelle's question
intrigued me as it has been one I've been pouring over recently.  My
undergraduate work here at Iowa State has been in horticulture with one of
my emphases being plant breeding/genetics.  The longer I've thought about
the quandary of remontant irises it seems to me that the situation is
behaving like a quantitative trait; that is a trait controlled by many genes
(generally more then 3 and upwards of 30 or even more).  A common example of
this would be tomato size which is controlled by approximately 30 genes.
Each of these genes is referred to as a quantitative trait locus (QTL).  As
with non-quantitative traits, different alleles can occur at each of these
loci yielding an enormous array of possibilities depending on the number of
QTLs involved.  To further add to the complication, though we've readily
observed this with rebloomers, is that environmental conditions can
influence the degree of expression of these traits.  We see this most
noticeably with cultivars that rebloom more reliably in the south vs. the
north or on acid soils vs. alkaline soils, etc.  

 

So this leads us to a formative answer to Francelle's question: yes!  You
can think of a cross between nonrebloomers (who may carry let's say 15 each
of the QTLs necessary for rebloom to occur) like an addition problem (for
those more scientifically inclined, pardon the generalization).  While it
really isn't that simple as adding QTLs until you reach a magic number, the
idea that a cross involving these two could yield offspring with near, more,
or exactly the "magic" number of QTLs is certainly probable.  And obviously
a mechanism like this does occur because we have cultivars that rebloom
reliably throughout much of the country, though markedly influenced by
climate.

 

For a little "light" reading on the subject you might browse to:
http://www.sciencemag.org/cgi/content/full/sci;289/5476/71 for a review of
quantitative genetics.

 

I've got more to this hypothesis but my calendar alert just reminded me of a
4:00 meeting.  Happy irising!

 

--Kelly

 

 

<<Date: Mon, 22 Oct 2007 17:56:45 -0700

From: "FRANCELLE EDWARDS" <FJMJEDWARDS@worldnet.att.net>

Subject: [iris] HYB:  Rebloom inheritance

 

I am also very interested in rebloom inheritance.  I had several seedlings
from Orange Plume X Betty Dunn.  Only one rebloomed for me.  It is uniquely
beautiful, but has health problems.  It had a nonreblooming sibling with
identical appearance, that I mistakenly crossed with When You Wish, a
rebloomer.  The seedlings are growing well.  What are my chances that some
of them might be rebloomers.  That is, do nonreblooming seedlings from
reblooming parents carry genes that might give rebloomers if crossed with
other rebloomers?

 

 

 

Francelle Edwards  Glendale, AZ  Zone 9

>> 

Horticulturally,

 

Kelly D. Norris

Advertising Manager, The Iowa Horticulturist

Contributing Editor, Garden & Greenhouse

Editor, Dwarf Iris Society of America

Bedford, IA 

Zone 4b/5a

Read my column?  Heard me lecture? 

Check out my website:  www.kellydnorris.com

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