Breeding for improved beta-carotene

[bower]

Very interesting, Chris! It is a real piece of luck that the modifier also changes the color in the intermediate stages.

I wish I knew of more indeterminate Beta OP's that are larger than Jaune Flammee. (Great tomato all the same, I was impressed with the earliness and production from the seed you sent me, thanks!). If you had some larger fruited that are already beta, it would save you a lot of space and time, since size is one of the hardest things to recover from crosses with small fruit.
I could send you seed of my F4 out of Zolotoe Serdtse, which is paste shape and size, but presumably Beta/- and sp+/- with whatever semideterminate genetics also in the mix, so still the linkage issue in play.

I would have expected the Beta - sp linkage to take a real beating in a cross of 97L97 and Jaune Flammee. I mean, I thought it should segregate normally because of linkage to both sp+ and sp-.

[crmauch]

Originally Posted by bower

Very interesting, Chris! It is a real piece of luck that the modifier also changes the color in the intermediate stages.

It is lucky. But it can be tricky. I thought my F1's X with 97L97 were pure orange until they were *very* ripe when they finally got their blush.

Originally Posted by bower

I wish I knew of more indeterminate Beta OP's that are larger than Jaune Flammee. (Great tomato all the same, I was impressed with the earliness and production from the seed you sent me, thanks!). If you had some larger fruited that are already beta, it would save you a lot of space and time, since size is one of the hardest things to recover from crosses with small fruit.
I could send you seed of my F4 out of Zolotoe Serdtse, which is paste shape and size, but presumably Beta/- and sp+/- with whatever semideterminate genetics also in the mix, so still the linkage issue in play.

I think I would have some of the same linkage problems, and semideterminate is determinate w/ modifier genes. Size was even more of an issue last year. In the cross if 97L97 X Opalka the F2 was smaller than either original parent (oblong cherry size!)

Originally Posted by bower

I would have expected the Beta - sp linkage to take a real beating in a cross of 97L97 and Jaune Flammee. I mean, I thought it should segregate normally because of linkage to both sp+ and sp-.

I don't believe so (I'm not a geneticist) but if we look at it this way instead:
MarkedUpJfx92.jpg

I marked the genes coming from JF with a diacritical mark(') and the genes from 97L97 with and asterisk(*). Note that the chromosome partners stay together (note, this is only for close linkages). So ultimately my breeding will be getting the Beta gene from JF and the modifier gene from 97L97 (The indeterminate sp+ genes will be coming from JF also).

[bower]

Okay I see that, makes sense! The modifier is the one that's not part of the linkage.

[Darren Abbey]

Originally Posted by crmauch

It is lucky. But it can be tricky. I thought my F1's X with 97L97 were pure orange until they were *very* ripe when they finally got their blush.

Interesting. I've been working with some white genetics which develops a pink/red blush very late in ripening. I hadn't come across descriptions of the trait elsewhere, so I haven't had much information to ponder on about it. I'll need to think of experiments I can do to test if these are the same trait or not.

[Andrey_BY]

Carotina (La Carotina) is one more a high carotene tomato variety.

http://tatianastomatobase.com/wiki/Carotina

[crmauch]

Originally Posted by Darren Abbey

Interesting. I've been working with some white genetics which develops a pink/red blush very late in ripening. I hadn't come across descriptions of the trait elsewhere, so I haven't had much information to ponder on about it. I'll need to think of experiments I can do to test if these are the same trait or not.

I'm pretty sure it's not, but it may be for similar reasons. Without the modifier gene, tomatoes with the Beta(B) gene are only 60% carotene, the remainder being mostly lycopene. The final 'blush' is the lycopene showing through.

I'm guessing your white genetics is a form of r (note that Beta does not work with r, only R.), but that "qualitative" or "bi-color' genes are causing a late addition of lycopene to the development of your tomato, but it's all conjecture on my part.

[Fusion_power]

White interrupts the carotene biopath prior to formation of the lycopene precursors but after the gene that produces green when ripe. The interesting thing about white is that the entire carotene biopath - including both lycopene and carotene - is still present and can produce pigments with a simple modification such as grafting onto a rootstock that has the correct gene. This is why a cross of white X green often produces a red fruited F1. This also explains certain published examples of graft translocation triggering changes in fruit phenotype.

[Darren Abbey]

Originally Posted by crmauch

I'm pretty sure it's not, but it may be for similar reasons. Without the modifier gene, tomatoes with the Beta(B) gene are only 60% carotene, the remainder being mostly lycopene. The final 'blush' is the lycopene showing through.

I'm guessing your white genetics is a form of r (note that Beta does not work with r, only R.), but that "qualitative" or "bi-color' genes are causing a late addition of lycopene to the development of your tomato, but it's all conjecture on my part.

Darn. I've been puzzling over this trait for some time and keeping an eye out for anything that sounds similar. I hadn't connected it to the bicolor trait, so that's something new for me to think about

[Whwoz]

I have recently become aware of a chance cross between Costoluto Genovese and Jaune Flamme. Having seen a photo of the F1's I wont dispute the parentage of the fruit as there are so few tomatos of JF's colour available down under and the fruit looked just like CG. Any thoughts on how the F2's will segregate out? Will the JF colour remain dominate over CG? what sort of size spread would we be expecting here and any idea how many plants would need to be grown out to find one or two with the size of CG give that small size is often dominate over large? Do not have seed but working on getting some. Thanks for any thoughts.

Woz

[bower]

The nice thing about Beta is that you can see if it's there, even in F1 or any heterozygous generation. The standard ratios apply to the color, so you would expect one in four to be BB in the F2, and two of four to be B/- visible as orange-red.
So you can always focus on recapturing size in any of the 3/4 F2's with a B allele showing. Then you can pick up the BB as 1/4 in a subsequent generation of maybe half dozen plants.

To get the size back, I would aim for 20 plants if you can do it. It is not easy and the ratio of 1 in 10 which Frogsleap found, may still not be quite full size of the largest parent. Chris can probably work out the ratio exactly, I'm just estimating. You would need more than ten to get one which also has a Beta allele. (I think the math is something like: 1/10 X 3/4 = 3/40 so roughly one in 14 plants might be large and Beta-allele, that is before probability calcs)

You could instead just aim to recover a Beta/- with the multi-locule trait fas, using perhaps 1/2 dozen plants, with the plan to take the largest multilocule fruit B/- or B/B and backcross it to CG or side cross to another larger fruit parent when you have selected a B/B full Beta.

[Whwoz]

Thanks Bower, space is not too much of an issue, more so if I can access seeds and convince the person who has the plant currently that I have some idea as to what is needed, if no luck, I will definitely be looking to re-make this cross.

Woz

[joseph]

Thanks for the seed. I planted 97L97 last night. I'm really looking forward to tasting a high carotene tomato, and using it in a breeding program.

[crmauch]

Originally Posted by Whwoz

I have recently become aware of a chance cross between Costoluto Genovese and Jaune Flamme. Having seen a photo of the F1's I wont dispute the parentage of the fruit as there are so few tomatos of JF's colour available down under and the fruit looked just like CG. Any thoughts on how the F2's will segregate out? Will the JF colour remain dominate over CG? what sort of size spread would we be expecting here and any idea how many plants would need to be grown out to find one or two with the size of CG give that small size is often dominate over large? Do not have seed but working on getting some. Thanks for any thoughts.

Just note that a cross with JF will give you a high Beta carotene with some lycopene as (I think the ratio is around 60% beta carotene and 40% lycopene) as JF does not have the modifier gene that brings the beta up to around 90%, so a JF cross will always be at most orange with a red blush.

Also remember that determinate/indeterminate is closely linked to the Beta gene on the same chromosome, so it will be difficult to get segregations of plant growth pattern and beta carotene genes.

As for size I think you might want to consider getting the cross somewhat stabilized (F3 OR f4) and then backcross it to the original parent for size.