Quote:
Originally Posted by StrongPlant
When it comes to genetics heterosis phenomenon is the one I've probably read the most about.And it's still not completely clear why it occurs.
I've seen it in action in tomatoes,but I noticed one interesting thing.
I made 3 crosses,the same strain of s.pimpinellifolium with 3 different s.esculentum varieties.Thing is,the cross with esculentum parent which was the most inferior in terms of yeld and vegetative growth gave the most vigorous and high yielding F1 out of the 3.Why would this be?
To me it made sense that if 2 parents are both superior genetically,that would make a better F1 then if one of the parents is inferior.
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I remember reading a book about breeding that overall wasn't all that useful as it was mainly about breeding grains and mass selection.
However, the author stated something at one point, paraphrasing here (breeding inferior to inferior is almost never useful, superior to superior is obvious and beneficial, but some of the most surprising and beneficial results are breeding inferior to superior). He didn't explain why.
If I had to guess, I would say that the inferior has so many homozygous genes that are slightly harmful that the hybrid created eliminates all these suppressed homozygous impediments allowing the hybrid result to be drastically improved.
I am somewhat surprised that you've seen so much improvement. I'm under the strong impression that though tomatoes do suffer some inbreeding suppression, that it wasn't that significant (as compared to corn, etc).
the Wikipedia article about heterosis was good and talked about the ideas of dominance/ over-dominance and epigenetics.