2019, August 2nd at 21:38 #25482HannahModerator
The more I read about peony hybridizing the more stupid I feel. So many new questions every day…
One thing I´ve been thinking about is about the quality of seedlings after a cross by the same parents, but with the difference that in group one you cross seeds from A x pollen from B, but in group two you do the opposite. Seeds from B x pollen from A. I hope you get me? Would you say the quality of the seedlings will be the same in both groups, if you have a fair amount of seedlings in both groups? Or are some great seed parents sometime crappy pollen parents and vice versa?
2019, August 19th at 19:59 #25502BobParticipant
Sorry that your question sat here for a while unanswered. I was not paying as much attention as I should have !
I understand what you mean. Should we see differences when we do a “reverse cross” ?
My sense is that theoretically there should be some differences. I’m not very knowledgeable about genetics, but since no one with more knowledge has answered, here’s my admittedly limited understanding. Apparently each parent does not contribute an equal amount to each seedling. It’s my understanding that the pod parent contributes some genetic “maternal DNA”, which the pollen parent does not bring along with it. So in that sense, the pod parent may contribute more to the seedling that the pollen parent does. What qualities are carried by this extra maternal DNA, and what influence it may have on seedlings I can’t say. And perhaps my understanding is wrong to begin with. But I think it’s possible that crosses done in different directions, using the same parents, might be different.
How one could tell might be hard to observe though, because in my experience, if you grow out 50 seedlings of a cross, there’s naturally quite a bit of variability. As a result, looking down a row of seedlings, one can often have a hard time trying to guess what sort of parents were involved. Some parents (like Blushing Princess) seem to make larger plants, and plants involving Old Faithful seem to make seedlings which bloom later in the season. So it’s likely that when crossing herbaceous varieties, you might not be able to see much difference between crosses that were made in one direction or the other. While they could be different, natural variability might obscure whatever those differences are.
Having said that, if the genetic makeup of the two plants are quite different, it might make a difference. As I understand, there are one or two reverse Itoh crosses, and the plants from those crosses do look different than from crosses made in the normal direction. Crosses between complex garden varieties and wild species might also produce differing results if done in different directions.
Again, others are sure to know more about this than I do.
2019, August 29th at 09:47 #25505sabrina-solskinParticipant
Bob is right..its called
Or ´Cross back `
But, as i learned by Don Hollingsworth – there is a natural barrier to the parents
Also it would be good you read, the post in the library..where some early breeders have done it and write about it – Because in the 2 generation of 2 parents.. there is a low fertility.. but we have found that growing them more years.. they get more mature .. so they might be able to make seeds..
Also you could learn to test the pollen ( also in this articles ) for fertility..as because you see lots of pollen it can be infertile.. and doing crosses with infertile pollen gives nothing.
Collect your own section of parents .. .make your own crosses.. raise theese – new generations – make selections by the best – choose your goal
Even it is a small section.. it will give you lessons about.. what to do
As practicing is the best way to learn
2020, December 10th at 16:47 #27279RogerParticipant
I read your question quite a while ago, and recently read this in Carol Deppe’s book Breeding your own vegetable varieties. Bob had the gist of it quite right.
“The Cytoplasmic in Inheritance
More than 99 percent of the genes in plants are arranged on chromosomes located in the nuclei of cells, and they are inherited according to Mendel’s laws. However, some small fraction of genes are located on organelles in the cytoplasm, and they aren’t inherited in this way. Even though there aren’t very many extrachromosomal or cytoplasmic genes, they have a disproportionate importance in plant breeding. The inheritance of genes in cytoplasmic organelles is completely non-Mendelian. It is almost always exclusively maternal. The egg is a big cell with a lot of cytoplasm. The pollen is a very small cell with little cytoplasm, which is not normally transferred to the egg during fertilization. Nuclear DNA comes equally from both parents, but cytoplasm comes only from the maternal parent. Once in a while you can do a cross where one of the characteristics you are interested in is associated with a gene that is cytoplasmic instead of nuclear. Suppose you do a cross between a variety that has a mottled coloration pattern on the leaves and one that does not. If you cross a mottled female to a normal male, some or all of the F1 plants are likely to be mottled. But if you cross a mottled male with a normal female, none of the F1 plants will be mottled, nor will the offspring in any future generations. The cytoplasm is relevant to us in additional ways. The cytoplasm of a variety and its nuclear genome have evolved to be compatible. When distant relatives are crossed, sometimes the cytoplasm and the nuclear genome of the F1 or of some of the F2 progeny aren’t compatible. In extreme cases lethality results. In less extreme cases the plant may be sterile or pollen-sterile. Male-sterile cytoplasms have, in fact, been useful in the production of hybrids. Such cytoplasms aren’t absolutely male-sterile; they are sterile only in the presence of one or more nuclear genes. Anytime we are crossing two fairly distant relatives, we we need to realize that the reciprocal crosses might be genuinely different. Both will give rise to the same nuclear genotype, but they will set it down in the middle of different cytoplasms. This could have a dramatic effect on the phenotype of the F, and subsequent generations. Many modern crops trace their nuclear genomes to only a dozen or so sources. But it is common for vast fractions of a modern crop to have only one cytoplasmic genome. The Southern corn blight in the United States in the early 1970s was caused by the blight sensitivity of a particular cytoplasm – a male-sterile cytoplasm that was in virtually the entire commercial crop, whatever the nuclear genome involved. Whenever we do a cross using a particular variety as the maternal parent, we are preserving its cytoplasm and discarding that of the male. I think we should pay more attention to preserving and increasing the diversity of the cytoplasms in our food crops. All we have to do to preserve a particular cytoplasm is to make sure that we use it as the female parent when we do crosses.”
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