Crossing tomato noob question.

[bower]

Originally Posted by BigVanVader

Thanks bower. Here is another question. I'm growing a bicolor det. from Joseph Lofthouse. It is early and cold tolerant. If I crossed your cross with that, then backcrossed the F2 back to yours. Wouldn't that increase the odds of finding the det/early/black fruits/earthy flavor genes? I'm going to do several different crosses this year.

Cool! I've been meaning to grow that one myself... You could get some really interesting fruit, and they'll all be determinates from the F1 onward.
I'm not sure at all about the genetics of bicolor - not much is written about it, and I haven't done any bicolor crosses so no observations to report.. KarenO could tell us something about the ratios that she got.
In any case, it is independent of the gf (black fruit).
So just to answer about your backcross plan, at least for the simple recessive black fruit gf,
JL bi F? (-/-) X Rodney F4 (gf/gf) - the F1 will be (gf/-) so not black.
(Since the parents aren't stable, you can expect variation in the F1, so I would advise to grow several and take F2 seeds from the best. )
JLbiR F1 gf/- X Rodney F5 gf/gf would give you 1/2 black offspring
while the growout of JLbiR F2, the odds of gf/gf are 1/4.
(You also have the same odds of (-/-) in the F2, that is, no gf allele 1/4. And 2/4 will be gf/- so although not black the allele is still there. If you backcrossed the F2 to Rodney F6 randomly in this generation, the odds of black fruit would be 3/4).
So you don't need to wait til F2 to increase the odds of black fruit and flavor genes from Rodney if you want to do that. You could also cross back to Rodney after you ID the black fruit in F2 if you want to, for 100% black fruited with variance in the other traits.

Traits like taste, cold tolerance, earliness are complex and they are additive involving multiple QTL's (many genes involved). What is really cool is that you can get unique flavors emerging from combination of parents, also earliness and cold tolerance combinations that are an improvement on either of the parents.
That is not even to mention the 'tricolor' effects from crossing black and bicolor.
So the main thing really is to play along with what nature provides you to select from. If you have the chance to do some backcrosses, do them and stash away the seeds, is my attitude. You may decide you want to use it somewhere down the line.

I will be interested to hear, whether Joseph's bicolor is earlier and more cold tolerant than Rodney. There is room for improvement, always!

[bower]

Wow so many posts while I was muddling along trying to write one.
Important point Fred made, each time you backcross you're starting over at F1, so it will take another 7 generations to stability (more or less).

[BigVanVader]

Originally Posted by bower

Wow so many posts while I was muddling along trying to write one.
Important point Fred made, each time you backcross you're starting over at F1, so it will take another 7 generations to stability (more or less).

Yeah. I think as long as it was in the first or second generation it would be fine, but again I'm a total noob so I probably have no idea what I'm talking about. Very exciting stuff though, besides I'm sure we can find some Florida growers to help us speed up stabilizing. I'm looking at you Marsha

[bower]

Fred, I'd love to learn more about the trait stacking approach...
What do you do with your 15 F1's? Cross them with each other?

Oh I just re read your post... the exceptional hybrid is the point! Sorry.

[tpeltan]

Originally Posted by bower

Important point Fred made, each time you backcross you're starting over at F1, so it will take another 7 generations to stability (more or less).

With F1 parents. The stability of of the backcross should be similar to the stability of recurrent parent, but this parent can be stabilized during the backcrossing increasing the stability of backcrosses.

[bower]

hi tpeltan, welcome to T'ville.
Actually I saw your post in my inbox before you deleted it - and it made perfect sense. If you backcross to one of the parents, or to a sibling in the same line, you're still moving towards stability. indeed, more homozygous genes is bound to result.
It does get a little tricky to reckon, just when will it be completely stable. maybe seven generations is a good bet, whether you backcross or not. At least for us amateurs.

[BigVanVader]

Originally Posted by bower

Cool! I've been meaning to grow that one myself... You could get some really interesting fruit, and they'll all be determinates from the F1 onward.
I'm not sure at all about the genetics of bicolor - not much is written about it, and I haven't done any bicolor crosses so no observations to report.. KarenO could tell us something about the ratios that she got.
In any case, it is independent of the gf (black fruit).
So just to answer about your backcross plan, at least for the simple recessive black fruit gf,
JL bi F? (-/-) X Rodney F4 (gf/gf) - the F1 will be (gf/-) so not black.
(Since the parents aren't stable, you can expect variation in the F1, so I would advise to grow several and take F2 seeds from the best. )
JLbiR F1 gf/- X Rodney F5 gf/gf would give you 1/2 black offspring
while the growout of JLbiR F2, the odds of gf/gf are 1/4.
(You also have the same odds of (-/-) in the F2, that is, no gf allele 1/4. And 2/4 will be gf/- so although not black the allele is still there. If you backcrossed the F2 to Rodney F6 randomly in this generation, the odds of black fruit would be 3/4).
So you don't need to wait til F2 to increase the odds of black fruit and flavor genes from Rodney if you want to do that. You could also cross back to Rodney after you ID the black fruit in F2 if you want to, for 100% black fruited with variance in the other traits.

Traits like taste, cold tolerance, earliness are complex and they are additive involving multiple QTL's (many genes involved). What is really cool is that you can get unique flavors emerging from combination of parents, also earliness and cold tolerance combinations that are an improvement on either of the parents.
That is not even to mention the 'tricolor' effects from crossing black and bicolor.
So the main thing really is to play along with what nature provides you to select from. If you have the chance to do some backcrosses, do them and stash away the seeds, is my attitude. You may decide you want to use it somewhere down the line.

I will be interested to hear, whether Joseph's bicolor is earlier and more cold tolerant than Rodney. There is room for improvement, always!

Wow bower thanks so much. This is going to be very interesting!

[BigVanVader]

My brain just melted.

To clarify for my benefit. So your saying make 6 specific crosses or 6 pollen donors then cross that with the mother plant?

But, using a hybrid approach does require that if you want to have recessive traits show up in the hybrid, you will need both parents to be recessive.

So if I wanted a PL det I would have to use 2 PL varieties correct?

[Fred Hempel]

Yes, if you want a potato leaf hybrid, both parents need to be potato leaf.

No. With a hybrid approach, the ultimate goal is for an exceptional hybrid that you produce over and over.

The crosses are unique crosses between parents

For example, if you have 6 parents, the crosses you can make are --

1 X 2
1 X 3
1 X 4
1 X 5
1 X 6
2 X 3
2 X 4
2 X 5
2 X 6
3 X 4
3 X 5
3 X 6
4 X 5
4 X 6
5 X 6

15 total crosses (not 20)

[BigVanVader]

Originally Posted by Fred Hempel

Yes, if you want a potato leaf hybrid, both parents need to be potato leaf.

No. With a hybrid approach, the ultimate goal is for an exceptional hybrid that you produce over and over.

The crosses are unique crosses between parents

For example, if you have 6 parents, the crosses you can make are --

1 X 2
1 X 3
1 X 4
1 X 5
1 X 6
2 X 3
2 X 4
2 X 5
2 X 6
3 X 4
3 X 5
3 X 6
4 X 5
4 X 6
5 X 6

15 total crosses (not 20)

Ok I see. Thanks Fred! You da man Think you could answer about 1k more questions today?

[BigVanVader]

I found this one at Tania's http://t.tatianastomatobase.com:88/wiki/Siniy Looks like it might be a good parent for a hybrid cross.

[jmsieglaff]

Hi Fred,

The Madera tomato is sure a nice looking tomato.

I reminded me of a tomato I grew in 2017, Garnet cherry. Have you ever grown Garnet? If so, how do the two compare?

We really liked Garnet in 2017--foliage health, extremely vigorous, very high production and excellent flavor and are growing it again in 2018.

Justin

[Fred Hempel]

Another person also mentioned Garnet, and they seem to look similar. We will definitely be growing Garnet this year!

Originally Posted by jmsieglaff

Hi Fred,

The Madera tomato is sure a nice looking tomato.

I reminded me of a tomato I grew in 2017, Garnet cherry. Have you ever grown Garnet? If so, how do the two compare?

We really liked Garnet in 2017--foliage health, extremely vigorous, very high production and excellent flavor and are growing it again in 2018.

Justin

[Fusion_power]

It also delays for another generation the process of developing a true-breeding line.

Strictly speaking, this is not entirely true. If the parent used for the backcross contains most of the desired genes and only one or two genes are being introgressed, a backcross can significantly speed up (or reduce the number of plants that have to be grown) the process of stabilizing a true breeding line. In other words, you are correct, but there are times when different logic is needed.

[Fred Hempel]

I agree. Introgressing 1 or 2 genes into a line clearly is one example.

Originally Posted by Fusion_power

Strictly speaking, this is not entirely true. If the parent used for the backcross contains most of the desired genes and only one or two genes are being introgressed, a backcross can significantly speed up (or reduce the number of plants that have to be grown) the process of stabilizing a true breeding line. In other words, you are correct, but there are times when different logic is needed.