Re: RE:HYB:Glaciata-genetics-second thoughts

Some second thoughts re glaciata genetics. I sent my message off very 
quickly this am without as much thought as it deserved. Jan may very 
well be correct re glaciata out cross/back cross ratios. It depends 
if glaciata "pla' is a variation of an allele (occupies the same site 
but has a different effect) or on a seperate gene site (a different 
gene but having an effect on expression of first gene). Current 
theories would suggest that it is a variation of plicata and thus on 
the same gene locus. This would mean that it is the plicata gene as 
expressed by that plant. There had been the suggestion by Wickmeyer 
in 1971 that the luminata gene may be on a seperate gene locus. My 
experience would suggest that there are two gene sites present when 
you are dealing with luminata/glaciata/plicata variations. Thus you 
would need both sets of recessives, whichever they are. Granted most 
of my experience is with SDB where the 8/8/12/12/ sets of genes with 
plicata/luminata/glaciata genes operate a bit differently. At this 
point you need to consider the amphidiplod factors with genes 
operating in sets of two pairs rather then four independents sets. 

Thus, if glaciata gene is "pla" and a variation of plicata  and on 
the same gene site, then it will work as Jan indicated. If it is on a 
seperate gene site and acts as a modifier gene then it will work as I 
had outined and you would need both sets of genes in full recessive 
form for expression. I beleive that there are two sets of genes on 
diferent sites. The second site could either be for the luminata gene 
or for the glaciata gene or both. This  certainly enters into 
theoretical areas. I will need to reflect on this some more and go 
back to my hybridizing  records to pull out the information I have.


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