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--- In iris-talk@egroups.com, "Paul Black" <midamerg@e...> wrote:
> Thanks Gerry for reminding me that when we make a statement, 
> we end up with more questions than we can answer.  Thank you Chuck 
> also for all helping us try to understand these patterns.  
> In Oklahoma and other less favorable growth areas, 
> plicatas/luminatas/glaciatas (plg for short) are generally weaker in 
> growth and disease resistance.  There are exceptions to this.  So, 
> what does that tell us?  You are certainly correct in questioning my 
> linking recessive patterns as a direct causative factor of these 
> weaker characteristics.  I think Chuck is headed in the right 
> direction.  
> First, we have a lot smaller breeding population to choose from and 
> end up using parents that have less than ideal genes to pass on.  
> Second, if we have chosen parents to use that have these flaws, we 
> also know that those flaws will be passed along at the same rate or 
> a greater rate than the traits we want.  If we look at where most of 
> the line breeding of "plg" came from and the weaknesses of those 
> lines, it is easier to understand the associated weaknesses that 
> now.  
> Third, there are those linkages that occur that are hard to break.  
> Again, someone with a better scientific mind than mine will have to 
> work this one through.  One example I get when I talk with other 
> hybridizers is that when you get the luminata pattern, you also get 
> poor branching and few buds.  It seems hard to break this link, but 
> isn't impossible. 
> This is off the "plg" pattern, but a link I found interesting.  One 
> aspect that makes it even more intersting is that the cross was made 
> both ways.  The cross was (Mystique X Twist Of Fate) and the reverse 
> (Twist Of Fate X Mystique)  It was a cross that yielded wonderful 
> seedlings.  There was just one problem and it occured in both 
>  As the intensity of the ruffling and "great form" and contrast of 
> light to dark in the standards and falls increased, so did the 
> incidence of overbloom.  I could walk down the row and the seedlings 
> with the prettiest form and ruffling and nearest to white standards 
> and black falls would be totally bloomed out.  There would be 4 or 5 
> bloomstalks and no evidence of an increase whatever.  This pattern 
> isn't normally associated with overbloom, but in this case, it was 
> very closely linked to it in some way.  
> Back to Gerry's question.  As "they" say, selection is everything.  
> Well, and maybe a bit of luck too.  If we have selected parents 
> on the best phenotypic and genepotypic traits possible for a 
> particular pattern, be it dominant or recessive, we stand a far 
> chance of maintaing the plant and flower quality we want.  Even at 
> that, there are always surprises - good and bad. 
> Paul Black
> Zone 8  Salem, Oregon 
> In iris-talk@egroups.com, Gerry Snyder <gerrysnyder@m...> wrote:
> > PAUL BLACK wrote:
> > > 
> > > ....  That is one of the hazards of
> > > working with recessive patterns is that they are usually weaker.
> > 
> > Any ideas about how much of this effect is directly caused 
> > by the visible recessive patterns, and how much by other genes 
> > that got concentrated in these cultivars by the line-breeding 
> > used to develop them?
> > 
--- A few additional thoughts. There are many different sets of genes 
that make up each chromosome and they each effect one or several 
characteristics, sometimes in an interactive way rather then just 
directly. When you use line crosing  and back crossing to establish a 
recessive factor you also decrease the variability of a number of 
other genes which control vigour, cold tolerence, branching, bud count 
etc. Thus you can get stuck with some undesirable traits with little 
or no variation in the gene pool of potential crosses. Thus as you 
maintain the desired new trait you are also linking yourself into some 
bad characteristics. To get rid of these you then need to do some out 
crossing . This is where a knowledge of genetics comes in. If you 
understand the genetics of the pattern you are working with you can 
select unrelated parents that have the same desirable genes and can 
introduce variability and vitality back into the desired type. This is 
what I did with Eramosa Snowball. As the pollen parent  was a week 
plant I crossed it with a plant that I knew had the glaciata genes and 
 vigour and was able in one generation produce an introducable plant 
of the desired colour. If I had done a sibling or back cross I could 
have easily trapped myself into some very undesirable characteristics 
that would have been hard to eliminate.
 I can very clearly see some desirable crosses to get luminatas to be 
very hardy, based on my current exploration of plicata genetics. The 
desirable paarents are there and they are exceptionally hardy. You 
wouldn't know from looking at them that they have the desirable genes. 
For a hint, look up an article by Robert Schreiner in the Bulletin, I 
believe 1985. More later. I'm hoping first to get some comments on 
what I have written so far. Challenges or reports of crosses that 
confirm or deny what I have speculated on.

A further possibility of weak lines is closely linked genes. This 
happens when a gene controlling a bad characteristic is very close 
(distance wise) to the new gene for the new characteristic. The closer 
genes are on the chromosome the less likely they are to separate and 
recombine with desirable genes  during the formation of the genetic 
material (pollen and egg cell). This link can eventually be broken but 
also requires out crosses , perhaps many attempts if they are very 
close. They then have to be established by sibling/ backcrosses with 
ruthless selection for he desired characteristic, initially 
giving second selection to beauty and color and selecting first for 
form , vigour, branching etc. The colours and beauty will come back 
with more breeding. You have to first select for the characteristics 
that are hardest to establish for that colour variety/pattern. 

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