Discussion from Facebook Apple group

sandbur

5 year old buck +
If you have only one tree of a self fertile apple variety, such as dolgo or antanovka, does each seed have the exact same genetics? No other apple trees to supply pollen in the area.

The discussion was getting into what type of apples to expect from seedling rootstocks.


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If no other genes are available to cross, then yes. Aside from minor mutations to the bud that produced the apple which produced the seeds, the seeds would have to be genetically identical to the parent tree.
 
I would say related but not identical but I'd need to research it to be sure how to make the proper scientific argument. But my rationale is as follows. The pollen and ovum each have half of the genetics. For those genetics to recombine in each seed to create a clone, you'd have to argue that every pollen was identical and every ovum was identical so they recombine the same. But if that were the case, every cross for a pair dolgo and antonovka trees would also produce seeds that were an identical mix. Every seed in every apple would produce an identical tree. But apple sex doesn't work that way.

Instead, I think that each pollen and ovum from the same tree are different split of the original genetics. So each resulting self-cross is unique. So if a Dolgo has a gene pair of dominant red leaf and recessive green leaf, you'd expect the self-crossed seeds to 25% red/red, 25% red/green, 25% green/red, and 25% green/green. Then 75% of the seedlings would be red leafed and 25% green leafed (assuming that leaf color is all controlled by a single gene but I think it is actually more complex than that).

The exception is for trees that produce apomictic seeds, in which case all the genetics are a clone of the mother tree and the source of the pollen (self or cross) plays no role.

The third scenario is parthenocarpic where the flower was not fertilized by the pollen but produces fruit without seeds.
 
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I think Chickenlittle is right. With sexual reproduction there is a unique combining of male and female DNA. It is easier to think about this in human terms. Brothers and sisters come from the same basic DNA from the same parents. They are closely related but not identical. Identical twins occur when a single egg is fertilized by a single sperm and then splits after DNA combines. Fraternal twins occur when 2 eggs are fertilized in the same pregnancy.

So, why do fraternal twins seem more similar than a brother and sister? The answer is probably a combination of epigenetics and nurture. Epigenetics is the study of which genes are expressed. We know the developmental environment impacts epigenetics, so two fetuses developing simultaneously in the same womb should be developing in a very similar environment and compared to siblings born 9 months or more apart. There nurture environment is likely more similar as well.

Back to trees. So, I can think one can expect that trees that are self-fertilized would be "more true to seed" than those produced from a tree fertilized by pollen from another.

I've been thinking through this for my Tigertooth jujube trees. They are grown on their own roots. I've propagated them through root cuttings and suckers but I have not found these trees to be real vigorous. I'm now considering trying to propagate them from seed since they are self-fertile. I'm sure the fruiting characteristics won't be identical, but they should be close.

Thanks,

Jack
 
In daylily breeding the results of using a plants pollen on itself produce plants usually with some characteristics similar to the parent plant but I have not seen any offspring that were the same as the parent plant.
 
I'm not sure if this information is on point or not, but there is a variety that was used to grow seed-grown rootstock in Germany and England in the 1800s that reportedly grew quite true to the seed of the mother tree if not grafted. The German language apple tree growing blogs I read a while back said it was because it bloomed really late, after the other apple trees were no longer blooming, so there was nothing for it to cross-pollinate with. It is still grown in orchards around the town it is named after. Unfortunately, I can't remember the name anymore, though I think the German word "Dorf" is in the name somewhere. I recall looking at US seed pricing online back then and the price was astronomical. That's all I remember about that anymore.
 
Certain varieties were used for seedling rootstocks. In Canada, seedlings from a variety called Beautiful Arcade were used for rootstock. Said to be cold hardy and give a tree about the size of a tree on MM.106.
 
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