Re: :HYB:Pod Vs Pollen Parent

In a message dated 10/19/2002 5:31:52 PM Mountain Daylight Time, 
Autmirislvr@aol.com writes:


> Makes sense to me.  You can't get much wider than the plicata X amoena 
> crosses. In the beginning, before I knew everything, <g> I constantly 
> bugged 
> the experts for advice. I was told to use my "best" cultivar as the pod 
> parent since it would contribute most of the genes.  
> 
> Another bit of advice I was given was to use my seedlings as the pod 
> parents 
> in 'out' crosses. I've not fully understood the reasoning behind this 
> advice. 
> I would think that good qualities would be the prime criteria.  Anyone know 
> why this might be good advice? Or not?  

Well......    At least plicata & amoena have the same number of chromosomes 
per set -- but I agree that this pairing fits the model.   My own experiments 
were with onco [10],  regelia [11], and bearded [12] maternal lines.  


Sometimes the advice you've cited is excellent, sometimes following it would 
be counter-productive -- BUT there is actually sound reasoning behind it.  

The purpose of an outcross is to bring new genes into a line or increase the 
dosage of specific ones.  Because most traits are transmitted chromosomally, 
by using our own stock as pod parents we are reducing the chances of also 
adding traits we don't want.   

Then there is the question of numerical advantage.  One pollinated flower can 
set, at most, one pod.  The pollen from that flower, however, can produce 
several pods.  So using seedlings as pod parents should increase the number 
of offspring produced -- which also improve the chances of getting something 
remarkable.

OTOH, when the trait we're trying to reinforce is an extra-chromosomal one or 
its expression is influenced by extra-chromosomal DNA there will be cases in 
which it is more effective to use our own stock as pollen parents.

None of which would keep me from trying to make the cross both ways!

Sharon McAllister





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