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Old August 22, 2009   #1
huntsman
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Default Please explain F1, F2, F3...

I encountered F1 for the first time on my pepper forum, but really don't understand a few points:

1. If I plant F1 seeds, will the seeds from the resultant pods be viable, or do I have to buy more seed?

2. Is an F1 plant hardier than the non F1, in general?

3. Can two different F1's hybridise?

Cheers!
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Old August 22, 2009   #2
TZ-OH6
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A little background...

For crosses you have parents (P) and offspring (Filial generations) F1 = children of parents, F2 = grandchildren, F3 = great grandchildren, etc.

At its simplest, vegetable varieties have two sets of chromosomes, one from each parent. The forms of these genes (alleles) can either be the same (homozygouse) or different (heterozygous -e.g.regular leaf/potatoleaf), one type of allele often dominates/masks other forms (regular leaf form masks potato leaf form). Genetically stable open pollinated (self pollinating) varieties have homozygous genes so all of the offspring generations will be identical to the parent generation... i.e. they are genetically stable.

Horticulturally speaking, a hybrid is an F1 having parents of two different varieties, and is thus heterozygous at many genes. When that plant self pollinates creating F2 seeds/plants those seeds/plants are no longer hybrids, but they still have a mix of genes from the parent plants and those genes start to form new combinations.

Parent = potatoleaf X parent = regular leaf --> F1 Regular leaf (with RL+PL allels). F1's offspring (F2) = RL+RL, RL+PL, RL+PL, PL+PL.

So if you grow out seed from a hybrid variety you will get gene segregation for all of the genes that were heterozygous in that hybrid (color, leaf type, flavor components etc.)


Now for your questions

1) You mean if you plant seeds from the fruits of an F1 hybrid, which would be F2 seeds.... They will grow but be different from the F1 and each other.

2) Yes, F1 hybrids are often more vigorous than their open pollinated parents, but not always.

3) Yes, F1aXF1b will work. This is what effectively occurs in all wild populations because individuals are not genetically stable varieties (homozygus at all genes) in those populations. You and I would be classified as horticultural hybrids because we each had dissimilar parents.

However, if you made this cross F1aXF1b they would now be the "P" generation and the offspring would be F1 ... [F1xF1other = F1, F1xF1same = F2].



What is confusing is that biologicaly speaking, a hybrid is the offspring of two different species (Lion x Tiger) and all progeny (F1>>>>F100) will remain hybrids. In most cases this type of cross does not work because the genetic combinations are incompatible either directly (embryo cannot develop), or indirectly (the hybrid offspring get outcompeted by the parent species and cannot form a continuing population) Horticulturally we almost never see biogical hybrids for vegetables (the apricot x prune is one exception) even broccoli x cauliflower = broccoflower is not a biological hybrid because all of the Kale vegetables are of the same species.

Last edited by TZ-OH6; August 23, 2009 at 08:47 AM. Reason: typo
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Old August 22, 2009   #3
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I really don't understand it either. I just know an example of F1 would be hybrid tomato seeds I buy direct in a little packet from the store. If I saved seeds from that tomato, then those seeds would be F2. And so on.
At least I think that's what it is
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Old August 22, 2009   #4
travis
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1. If I plant F1 seeds, will the seeds from the resultant PODS be viable, or do I have to buy more seed?

You apparently are speaking of peppers here. Yes they will be viable if by that you mean that saved F2 seeds from your F1 hybrid plant will sprout and grow pepper plants. But the F2 plants from those seeds may not yield the same peppers as the F1 seeds did the first year. Some of the F2 plants may yield closely similar peppers and other F2 plants will yield significantly different pepper pods. Of course, the variability of the pods on the various F2 plants is dependent on the variability of the genes contributed by the two original parents to the F1 hybrid.

If you were speaking of tomatoes rather than peppers, there would be some more comments I could make. For example, and speaking more of modern hybrids, some breeders use for the seed bearing - or pollen receiving - parent of a modern hybrid a male sterile breeding line so that they don't have to emasculate the blossoms prior to applying the pollen to the female part of the flower. This saves a huge amount of labor as you can imagine. But the resulting F1 hybrid seed carries the recessive gene for male sterility and a percentage of the F2 plants grown from seeds saved out of the F1 hybrid tomato will bear no fruit in the second generation. You can even get an F2 plant that will bear fruit but carries the recessive male sterility gene forward and expresses the non-fruiting trait in the F3 generation. So, there is a case for you where the F2 seeds saved from an F1 hybrid may not be viable in that they will sprout and grow but not bear fruit.

Also, disease resistances in F1 hybrid peppers and tomatoes often are recessive traits while color and shape characterisitics are dominant traits. In the F2 generation you may lose disease resistance and a different color and shape may pop up. So if by viable you also mean replicating the F1 characteristics, then no and there is a high likelihood with modern hybrid peppers and tomatoes that the F2 seeds will not replicate the F1 hybrid.

Bottom line, if you want pepper plants or tomato plants whose growth habits, plant appearance, fruit appearance, disease resistances, etc. are identical to the F1 hybrid, yes you have to purchase the F1 hybrid seeds repeatedly.
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Old August 22, 2009   #5
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Do you remember the basic genetics they teach in high school? Remember that they would set up a basic punnets square to demonstrate simple inheritance?

A little refresher

I can't figure out how to draw a graph in this program, but imagine the little squares drawn around this demo.

R=Red pepper
Y= Yellow pepper
RY=Orange pepper

So, a seed company decides they want to sell an orange pepper to go with their red and yellow peppers. So, one season they breed the (R) red pepper with the (Y)yellow pepper to get a (RY) orange pepper.

...R ...R
Y RY RY
Y RY RY

All the plants of this First Filial Generation (F1) from carry one (RR) gene and one (YY) and produce (RY)orange peppers


So, you buy some seeds and have such lovely and tasty orange peppers that you decide to save seed and grow some more next season. Only, the starting genetic material of the orange peppers is not the same, so what you get in the Second Filial Generation (F2) is:


...R....Y
R RR RY
Y RY YY

About half of the plants you would get would be orange, and about a fourth would look like either the red or the yellow pepper parents. The problem is until the fruit is produced, you won't know which seeds you've planted.

And of course, in the real world there are a lot more genes involved in a F1 cross then a simple single one for color, which is why a lot of folks don't bother to save seed on F1 plants.

Last edited by Blueaussi; August 22, 2009 at 03:37 PM. Reason: I hate when the program tries to help me!
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Old August 22, 2009   #6
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Quote:
Originally Posted by Blueaussi View Post
And of course, in the real world there are a lot more genes involved in a F1 cross then a simple single one for color, which is why a lot of folks don't bother to save seed on F1 plants.
Unless you want to spend several years growing out the offspring generations and selecting the closest matches in order to create an open pollinated version of the original F1 seed...a process known as dehybridizing.

And yes, there should be, if enough seeds are planted a very nearly exact duplicate of the original in the F2 stage...most of the time. It also gets more complex when more than one gene pair controls a particular trait.

And without doing DNA analysis, it is nearly impossible to find that 'exact' match...that is why for things that take a fairly long time (like fruit trees) from seed to fruit bearing age, nobody bothers with seed saving/dehybridizing. Think of how long it would take to dehybridize an apple tree that takes 5 to 10 years to bear fruit from seed and five or more generations to achieve results. Tomatoes can take 5 to 10 years or so (less if you can grow them in a greenhouse or live in a mild climate and can get two crops in per year).

But it is a fun hobby, if you've got the time and space to dedicate to growing out a fairly large number of one variety.
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Old August 23, 2009   #7
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This site starts with the anatomy of a tomato flower and
then follows up with simple illustrations of the heterozygous
and homozygous gene pairs in F? generations and how
the probabilities work out in successive generations after
the initial F1 cross:

http://www.kdcomm.net/~tomato/Tomato/xingtom.html
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Old August 23, 2009   #8
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@ TZ - That was very detailed, and I think I got most of it, thank you!

One question that I might have misunderstood...

Quote:
Originally Posted by TZ-OH6 View Post
[F1xF1other = F2, F1xF1same = F2].
Following your explanation, would F1 x F1 other not result in a new F1??

@ Barbee - thank you

@ travis - yeah, my knowledge - such that it is! - is more in the realm of peppers, and your explanation is very useful..thanks!

@ Blueaussi, mjc and dice - thanks for the links and clarification. Wish I'd stayed awake in biology, now...
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Old August 23, 2009   #9
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Yes, you are correct, that was a typo on my part, it should be [F1xF1other = F1, F1xF1same = F2]. Thank for catching that.


If I cross BigBoy F1 x Momotaro F1, I get a new F1, but if I cross BigBoy with another BigBoy plant, it would be the same thing as if I let it self pollinate, therefore the offspring would be F2.


And because F2s are segregating each plant is genetically different from all of its siblings, crossing two F2s (a sibling cross) does not give you F3 the way it would if you let an F2 plant self pollinate, you get another F1. You would probably have the sibling parents of that cross name coded [e.g. F2sibA X F2sibB] so you are back to a situation with two different parents = F1.


The thing I have trouble keeping straight when lableing seed is that F# plant give me F#+1 seed. I keep accidentally labeling seed from F1 plant/fruits as F1 seed instead of F2 seed [which grows into F2 plant].
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Old August 23, 2009   #10
travis
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Crossing two F1s will give variable results because the two parents are 100% heterozygotous rather than homozygotous. Which is why breeders always use two homozygotous pure breeding lines to obtain marketable F1 seeds that all produce the same results.
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Old August 23, 2009   #11
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Well, I have a better idea now, thank you.

I had the idea that an F1 would produce fruit whose seeds would not even grow.

In fact a decent seed house should be producing F1s that are consistent and constant - gotcha!

Thanks fellas.
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Old August 28, 2009   #12
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Sometimes it just depends. I have a forum acquaintance who swears that she is on Brandy Boy F6 and that she can observe absolutely no difference among the generations.

People speculate from time to time that seed companies sometimes designate OP's as hybrids to minimize seed saving and increase seed sales. Is it pure speculation? I have no idea. But I tell you what, I'm going to start saving Brandy Boy seeds just to find out myself.
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Old February 12, 2011   #13
WillysWoodPile
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Default Please explain F1, F2, F3...

Could someone please explain F1, F2, F3 and so on to me.

My understanding is that one variety is crossed with another variety and those seeds are F1: but F2 is where I am confused. Is it F1 crossed with a third variety, or is it F1 pollinating itself?
A nice simple explanation in layman's terms would be most helpful. And a thorough one please because my memory isn't so good so I may need to refer back to this thread many times.
Thank you to those who's decades of knowledge is passed on to us, that we may pass it on to the next generation.
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Old February 12, 2011   #14
Lee
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Check out this discussion. Sometimes you have to know what
you're looking for to find the answer. Kind of a catch-22 in
this case.... as I had a hard time finding it and knew what to
look for.
Might be a good topic for a sticky in the Crosstalk forum...

Enjoy the reading.

Lee

http://www.tomatoville.com/showthrea...ghlight=filial
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Old February 12, 2011   #15
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We've several threads on this subject, but here's the basics. We'll use Celebrity as the example.

If I buy some seeds from, say, Ferry Morse, those seeds will be F1. That means it's a hybrid and is unlikely to reproduce the same size, shape, taste, etc is you save seeds from that F1.

But, if you did save seeds from that F1, then those seeds would be the F2. Grow out the F2 seeds and harvest fruit and save the seeds from the F2 plant and those seeds will be F3.

Etc. Etc.

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