Re: R: [CH] cross breeding
Brent Thompson (brent@hplbct.hpl.hp.com)
Thu, 13 Jul 2000 09:08:12 -0700
> If the seeds, held in a pod that is growed on a f1 hybrid-plant, will not
> keep the distinctive character of that plant, how the establishment of a new
> variety does it work ?
>
> From the arrangement of the genes of two standard varieties could you obtain
> only one f1 hybrid?
>
> Why from the seeds of one pod, that I once sowed, I obtained all different
> plants with different pods?
> If you have a plant and you would keep his character, how could you make?
Chile seeds are the result of sexual recombination of genes and this sexual
recombination of genes works just the same in chiles as all other
organisms. Each seed contains a combination of a more-or-less randomly
selected half of the genes from the mother and a more-or-less randomly
selected half of the genes from the father.
In the case of chiles, "father" means a single grain of pollen; each chile
seed was formed from one pollen grain combining with one ovum in the
flower. However many seeds a chile fruit contains, that many different
pollen grains were active in fertilizing the flower from which that fruit
arose. So, even if all those pollen grains came from a single plant --
possibly [often] the same flower which is being fertilized -- because each
of them contains a different random selection of half that parent's genes,
and of course same for the mother's genes in each ovum, the resulting seeds
will all have a different mix of genes, which will express when they are
grown out as being different plants. They will all be different in varying
ways, but they will very likely look similar enough to all be considered of
the same single variety, just as all Thais or Swedes or Samoans or Romans
tend to look similar compared to members of another of these groups.
But since there were many many pollen grains involved, it is entirely
possible that some or all of them might NOT have come from the same flower
itself, but via some bee or other insect just arrived from the completely
different variety you planted just next to our test plant. The seeds from
these "foreign" pollen grains will have genes randomly selected from a
quite different set than the first variety, so plants grown out from these
resulting seeds will potentially look wildly different, in unpredictable
ways, just as you never know what the children of a Thai married to a Roman
or a Samoan married to a Swede will look like, other than comfortably being
able to predict those children won't really quite look like any of the
parent "types".
Then, to establish a new variety having the characteristics you want, all
you have to do is breed those plants and their offspring together for a
long enough time that they consistently produce seeds that grow out to look
basically the same. Just the same as with human populations. Wherever you
go that the people look different from other places, it's because a group
of people with those general looks bred together in relative isolation for
enough generations to make a more or less uniformly distinctive population.
--- Brent