Color Predictability
 

Hi,

Last year I bred a purple and pink. The f1 was all pink (with a slight purplish hue).

The red x reds were red of course.

I don't really know which genes control for color. I also know the epidermis seems to have a different color gene than the inside.

Are there are any predictable outcomes for:

red x green

red x purple

pink x green

orange x red



thanks

I believe they will all be red flesh and yellow skin. Not certain about the purple to red cross...flesh might have a purple tint?

[url]http://frogsleapfarm.blogspot.com/2014/04/genetic-control-of-fruit-color-in.html[/url]

Very, very interesting, Thank you for posting that link Fred.
KarenO

You're welcome. The genetics of color is very complex.

For example -- I have gotten light pink tomatoes from crosses between an orange variety and a yellow variety.

Pigment synthesis pathways have multiple steps.

With regard to the above questions -- Red is usually dominant in the F1 generation. But I bet there are exceptions.

Green when ripe is also usually recessive.

Recessive traits, such as clear epidermis, potato leaf, colours other than red are fixed in the phenotype once expressed I am told. Is this without exception?
I have bred a bicolour, a black and a dark pink (some would say purple) clear epidermis, all hearts. (these were all selected from the F2 of one of my crosses)
Please tell me the F3 will produce the same, for sure, perhaps with more subtle (but important) variations...? size ,earliness, production, vigour, taste....

KarenO

A good deal of information is available about color genetics in tomatoes, including details of the pathway used by the plant to make the colors.
[URL="http://the-biologist-is-in.blogspot.com/2014/04/the-color-of-tomatoes.html"]http://the-biologist-is-in.blogspot.com/2014/04/the-color-of-tomatoes.html[/URL]

Recessive traits are by definition fixed once they're present, but not all non-red color traits are recessive. The B (for Beta-carotene) trait is a dominant orange, and the Gr trait is a dominant green, for example.

SnuggleKitten) It depend on what genes are at play in each parent.

KarenO) Bicolour, black, and dark-pink/purple can all be hiding other recessive color traits, so the subsequent generations won't necessarily be identical.

For both sets of hypothetical crosses, calculating the probability of different color outcomes would require much more information about which genes are found in the parent lines. This can be difficult information to come by in advance of making the crosses and finding out.

Not all recessive traits are fully recessive, and you may get results that surprise you in the F1, as well as successive generations if you are unaware of the exact traits with which you are dealing.

In terms of color, beta carotene is partially dominant, so when crossing a beta carotene (orange colored) tomato with a red tomato, you will not get a fully red fleshed tomato. The F1 will appear varying shades of very deep orange red depending upon the degree of lycopene content of the red parent ... for example.

Another example: Yellow x Orange. You need to know if the "orange" is tangerine. If so, you will get a red F1 tomato unless both parents have clear epidermis. Then you would get a pink tomato in the F1.

As to F3 replicating the F2 color, let's say you captured a yellow epidermis, green flesh (gf) on red flesh tomato in the F2 from a cross of a red tomato x Cherokee Purple. This F2 might be considered "black" by customary definition in this forum. Some of the F3s will instead be "purple" (green flesh (gf) over red flesh with clear epidermis instead of yellow epidermis).

Then in the F4, you will get some purely green-when-ripe which is yellow flesh stained with the green flesh chlorophyll. If these come from the yellow epidermis "black" F2 line, they most likely will have yellow epidermis and have an amber blush when full ripe. If they come from the F3 "purple" line and have clear epidermis, these green when ripes will not have the distinct amber blush, but may have a faint pink blush ... or even both may have red swirls in their interior flesh, becoming bicolor green when ripes.

These are just examples, and some of these color changes may occur in the F2 or in later generations from a Red x Purple or Red x Black cross.

Nothing is for sure.

If you have an assumed "recessive" color in the F3, you could still be heterozygous for modifiers that might change the color if they became homozygous in a later generation.

I wouldn't assume a particular coloration is fixed, until 20 plants in a generation are the same color.



[QUOTE=KarenO;461325]Recessive traits, such as clear epidermis, potato leaf, colours other than red are fixed in the phenotype once expressed I am told. Is this without exception?
I have bred a bicolour, a black and a dark pink (some would say purple) clear epidermis, all hearts. (these were all selected from the F2 of one of my crosses)
Please tell me the F3 will produce the same, for sure, perhaps with more subtle (but important) variations...? size ,earliness, production, vigour, taste....

KarenO[/QUOTE]

Great, thank you Fred, that helps.
Karen

So its kinda like the stock market, its all a fugazi...

No, it's more predictable.

Until you grow the seed out from a salmon colored tomato that was supposed to be Cherokee Green and get red, yellow, orange, pink, and green offspring. I'm still working through the genetics 7 years later to understand how this could happen.

[QUOTE=Fusion_power;461559]Until you grow the seed out from a salmon colored tomato that was supposed to be Cherokee Green and get red, yellow, orange, pink, and green offspring. I'm still working through the genetics 7 years later to understand how this could happen.[/QUOTE]

Then there's the time I grew two Galina's Yellow plants, seeds newly arrived from Siberia via Bill McDorman and saved seeds grew out plants that had either red or pink or orange or salmon or white fruits, all cherries. At the same time a friend was also growing the same newly arrived ones and he got the same. So he asked me to send him seeds for the best one, which was the white cherry, and it was he who named in Dr. Carolyn.

Did I spend a lot of time trying to work out the genetics? I did not.:)

Then one time I had four plants out of Cherokee Green for seed production for my SSE listing, two had typical CG fruits and two had fruits that were the same as CG but the fruits were white, and when I tasted them they were BS which is short for beyond spitters.;)

I do think on that one that it was Keith Mueller who told me how a GWR could go to white. And the cherry variety Green Doctors was also from a plant of Dr. Carolyn that appeared in Amy Fowler Goldman, as she's now known at SSE.

Carolyn

So back to square one. Its all....a fugazi......pixy dust.