F1 Hybrids - a question.

[greenfingered fiend]

I can't really remember my biology days at school.

If I have produced plants from F1 seeds am I correct in thinking that they have to be self-pollinated to produce a continue supply of F1 seeds?

In other words do they resort back to a non-hybrid.

Not sure if this is making sense?!

GF.

[greenfingered fiend]

[supersprout]

Here's the science bit GF ;)
http://www.allotments4all.co.uk/joomla/component/option,com_smf/Itemid,57/topic,5672.0

[laurieuk]

Fi hybrids are "first generation" plants and you should not save seed from them as you are likely to get very dissapointed results. They are produced from selected parents and have to be grown fresh each year.

I can't really remember my biology days at school.

If I have produced plants from F1 seeds am I correct in thinking that they have to be self-pollinated to produce a continue supply of F1 seeds?

In other words do they resort back to a non-hybrid.

Not sure if this is making sense?!

GF.

[sally_cinnamon]

I'm having a vague recollection of a World Food Supply lecture at uni where we were told that people who sold seeds to the third world countries use F1 seeds because it meant that they would have to buy more seeds the next year for new crops (and in doing so would make more money - meanies), so I guess that meant that the seeds saved from an F1 plant would not be viable.....  ???

[saddad]

That's it exactly, like plant breeders rights and Genetically modified material it is all a commercial con. F1 don't save true but old varieties are open pollinated and can, some easier than others, be bred true to type year after year......
Peas, Beans, Tomatoes are the easiest to start with, Brassicas are much harder! As are most biennials!
;D

[mat]

They are viable - they will grow...

BUT F1's are crosses which will not "breed true" - seeds from which will have a % which grow exactly like each of the parents of your original plant.

Some people do sow seeds from F1's and "rogue" out any which look unlike they want them to

e.g.take a very simplified F1 self pollinated hypothetical example:
an orange flower is a cross from a red flower and yellow flower to produce an F1 hybrid
take the seeds produced by the orange flower and sow them
Some will grow orange, some yellow, some red, a few may be different still!
If you are happy with this - then carry on. 
People who are happy to do this "rogue" out the red and yellow ones and keep doing this every year (when fewer are produced) they then end up with a stable orange (non F1) flower which will eventually "breed" true, the individual can then enter this flower to trials...

For more detailed info, I would need to get my course notes out...

Yes, it does seem unfair to Third World Companies... but the other opinion is that they are stronger, adapted to specific requirements and are more likely to "survive"  take your pick... 

mat

[Toadspawn]

Many varieties grown on a commercial scale are F1 hybrids. As the result of a cross between two heterozygous variable parents ALL the plants are identical and homozygous. FI hybrids are selected because they show characters which are better than either parent such as yield, resistance to disease. This means that commercially they are superior to the parents because they all mature at the same time which means the whole crop can be harvested in one go.
Gardeners and third world farmers prefer growing crops that vary in maturity.
Seed produced by an F1 plant is heterozygous and if saved and sown it segregates into a population which has some plants like both the parents and some plants showing better or sometimes worse characters than either of the parents. (ref Mendels work using peas)
All plant breeding begins by crossing two parent plants showing desireable characters to produce an F1. Seed from the F1 which now becomes the F2 generation is sown and produces a segregating population. Individual plants may be selected from this population if they show desireable characters but if not, the whole population is discarded. Selected plants are grown for a number of years and each generation is reselected and undesireable plants are discarded. Eventually this will produce a stable population of a potentially new variety which can then be tested for agricultural value and distictness, uniformity and stability. It may then be granted Plant Breeders Rights and can then be sold commercially.  It may also be added to the NIAB recommended List. This process takes considerably longer than producing an F1 hybrid.
F1 hybrids must be produced new each year because they do not breed true whereas seed from standard varieties can be saved and grown each year.

[Robert_Brenchley]

Surely you mean that the parent strains, which are very inbred, are homozygous, and the hybrid is heterozygous?

[angle shades]

you are so right Sally, about the third world situation.I posted a thread in the' News' section of A4all about seeds and biodiversity on the food programme on radio 4 a month ago, its well worth listening to and explains about the national seed list and how supermarkets monopolise it, and how the third world gets a raw deal :(/shades x

[Robert_Brenchley]

Modern seed varieties have been a disaster for many third world farmers. They need loads of fertiliser, which only the wealthier farmers could afford, so the poorer went under. Then they weren't resistant to disease like the original local strains. By the time they cottoned on, many of the original strains had diasappeared.

[amphibian]

Modern seed varieties have been a disaster for many third world farmers. They need loads of fertiliser, which only the wealthier farmers could afford, so the poorer went under. Then they weren't resistant to disease like the original local strains. By the time they cottoned on, many of the original strains had diasappeared.

The other problem is that Mendelian breeding can only provide vertical resistance.

[greenfingered fiend]

Can I just clarify then.

If I have two plants from two F1 seeds and pollinate each plant with the others pollen will I get F2 seeds that are true to the F1 seed?

OR

If I take one plant and then self-pollinate will I get the desired seed?

OR

Well there isn't an or - How do breeders maintain seed output?

Surely there must be a way of ensuring seed stock remains true F1.

GF

[greenfingered fiend]

I have just read and re-read the threads. I think it is coming back to me now - Except the hetero- and homo-psychotic!!!

Looks like I need bigger seed beds for my trial by destruction. LOL!

Ta Loads.

GF.

[Robert_Brenchley]

Homo (Greek for 'the same') have two identical copies of the same gene, hetro ('different') have different versions. The first will produce offspring with the identical characteristic, the second, with differing characteristics.

[cleo]

I`m just a simple tomato grower. But not all F1s are so classified for scientific reasons-the best example I know is tomato `Sweet Million`-it`s an `F1` but comes true.

I don`t want to get involved in socio/political debate-but I seldom see the point in F1s for us `ammateur` growers with the exception of growing cucumbers.

Having said that I now shoot myself in the foot and suggest the hybrid tom `Santa` is worth growing-I wonder if that would come true though?-I`ll save some seed and try .

[Toadspawn]

Sorry yes I got the terms the wrong way around. I hope I didn't confuse too many people.

Parents are homozygous and breed true from seed.
F1 hybrids are heterozygous and do not breed true from seed. Therefore they have to be created new each time seed for growing a crop is required because saved seed segregates markedly and may produce plants like the parents or with any combination of the parent characters.

Surely you mean that the parent strains, which are very inbred, are homozygous, and the hybrid is heterozygous?

[Gadfium]

If I have two plants from two F1 seeds and pollinate each plant with the others pollen will I get F2 seeds that are true to the F1 seed?

A percentage of the plants grown from the F2 seed may show some characteristics of the F1 generation, but in general - nope. And the ones that do show similarities are not necessarily stable, they may even be sterile. It would need several generations of careful selection/selfing from the original F1s or the F2 seed (or backcrosses etc) to approach a stable variety with the requisite - and expressed - cropping/growing needs.

If I take one plant and then self-pollinate will I get the desired seed?

If it's an F1 that is being self-pollinated - nope. Same problem as above.

Each original stable parent breeds true to itself - though you get genetic variation within the population; artificially cross the parents, however,  and you get an F1 with a particular expression of characteristics... crossing an F1 with itself will not give you the same expression.

For example (Mendelian):

a) Take two parent breeding true: round peas and wrinkled peas
b) Cross the parents to get F1...

Parents       round x wrinkled
F1                     all round

Seems very straightforward, F1 peas are round, but... if you try to breed from the F1s, they do not come true....

c) Self the F1, and you get:

F1 x F1         round x round
F2               round & wrinkled (3:1 ratio)


Now if you toss in a second variable, that of colour, and repeat the experiment you get the following:

1. Parents - round yellow peas x wrinkled green peas
2. F1         - all round yellow peas
3. F2 (F1 x F1)  - 9 round yellow peas : 3 round green peas : 3 wrinkled yellow peas : 1 wrinkled green pea

Note that the number of F2s, resembling their F1, drops as the number of variables increases. The more variables you add in, the more complex the equations become, and the number of physical combinations expressed zooms upward!

Well there isn't an or - How do breeders maintain seed output? Surely there must be a way of ensuring seed stock remains true F1

They use the two original parent stocks (often inbred) to produce the F1s with the requisite characteristics; the F1 seed is then sold to the consumer. Keeping the identification of the parents secret maintains profit levels and allows F1s to be claimed as their own product.

[Robert_Brenchley]

There has at times been a similar situation with artificially maintained lines of hybrid bees. This is rather complicated to do, partly because of some odd genetics, and partly because they normally mate iwhile flying freely. Instrumental insemination is widespread, but produces expensive queens. In once case that I know of, four highly inbred, and thus homozygous (and also unproductive, given the genetic peculiarities of bees) strains were maintained in isolation. Two pairs of these were crossed to produce two unrelated F1 lines, and these were then crossed to produce the commercial product. The problem with all of these types of bee is that naturally produced daughter queens won't come true, and have a reputation for seriously bad temper. You don't want to know!

[fbgrifter]

Totally agree with gadfium, however unlike the pea scenario not all parents of F1 are edible.  particularly in the squashes group.  one parent may be an inedible (decorative) squash that has strong resistance to disease, or climbs well for example.  parent 2 may simply be tasty.  so F1 offspring could be tasty and a strong climber, or tasty and resistant to disease.  the problem arises when you grow seed from the F1, you may produce plants that are not even edible!