re: HYB: trying to learn some genetics terminology
iris@hort.net
  • Subject: re: HYB: trying to learn some genetics terminology
  • From: &* W* <i*@telp.com>
  • Date: Fri, 22 Feb 2013 07:53:28 -0700
Oh, and another comment about this terminology. It is most often used in 
the context of crossing two true-breeding (homozygous) parent types, to see 
how their genes combine in future generations. For food crops, for example, 
you will find that seeds described as "F1 hybrids" come almost exclusively 
from a process of developing two uniform and true-breeding lines, then 
crossing these together. Hybrid vigor results from such a program because 
the two parent lines will often have different deleterious recessives in 
their makeup, the effects of which are suppressed by the genes of the other 
parent.
Although it's not incorrect to refer to the seedlings of two heterozygous 
individuals as "F1 progeny", it can give a misleading impression of what 
the cross was about, what it was intended to show, etc. For most garden 
hybrid tetraploid irises, which have a nice big scramble of genes to begin 
with, I prefer to just call the seedlings "seedlings" (rather than "F1 
progeny"), and the intercross of the seedlings as a "sib-cross" (rather 
than "F2"). I would use the F1/F2 terminology, though, when talking about 
crossing two different species to find out which characters are dominant, 
etc.
Just my two cents.
Regards, Tom


   

Tom Waters   


Telperion Oasis ~ www.telp.com/irises    


Cuyamungue, New Mexico, USA (zone 6)  

----------------------------------------
From: "Tom Waters" <irises@telp.com>
Sent: Friday, February 22, 2013 7:22 AM
To: iris@hort.net
Subject: re: [iris] HYB: trying to learn some genetics terminology 

Yes, as Chuck has said F2 refers only to the result of crossing F1 
individuals from the same initial cross. I don't believe there is any 
special terminology for the cross of two seedlings of related but not 
identical parentage.

Tom Waters   

Telperion Oasis ~ www.telp.com/irises    

Cuyamungue, New Mexico, USA (zone 6)  

----------------------------------------
From: "Linda Mann" 
Sent: Thursday, February 21, 2013 7:16 PM
To: iris@hort.net
Subject: [iris] HYB: trying to learn some genetics terminology 

F1 & subsequent generations.

Online definition says F2 is > The progeny of self-pollinated F1 
generation plants

But I've also heard/read F2 used this way:
> The F2 (second filial) generation consists of the offspring from allowing 

the F1 individuals to interbreed - the grandchildren of the parental 
generation.

So what do I call the offspring of two related F1 seedlings that are not 
siblings, but are part of my non-line breeding program?  i.e., crosses 
between half sibs, cousins, etc.

I was assuming that any 2nd generation away from the parental one was an 
F2, but looks like that's not the way F2 is normally used.

Linda Mann

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