GWR Tomato genetics question

spiced_ham(z5 OH)June 4, 2009

Hopefully one of out resident tomato breeders will be check in to answer this question.

The Green Flesh mutant gene(gf) is responsible for chlorophyll retention in ripe fruit, resulting in the mucky color of black varieties, but what corresponding mutations are responsible for the lack of red and orange pigments in the Green When Ripe varieties (Green Giant etc). And are they the same for the white varieties such that you can eventually get a GWR by crossing a white with a black variety?

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mulio

but what corresponding mutations are responsible for the lack of red and orange pigments in the Green When Ripe varieties (Green Giant etc).

a green when ripe is possible two ways:

1) when the gf gene and the r (yellow) genes are both present in a homozygous pairing gf/gf + r/r
that is what produces a non-black type (or purple depending on the skin color).

And are they the same for the white varieties such that you can eventually get a GWR by crossing a white with a black variety?

whites are variations on the yellow gene. The yellow gene r has several alleles which alter the amount of yellow pigment. A white could have the gf or not.

2) The second type of GRW is a dominate gene for green fruit which is not very common. Green ripe Gr. It is green fleshed with red in the center. To complicate that somewhat, one could have a gf that also has ry (gene for yellow red bicolor) and that might mimmick a Gr (green with red center). Gr fruit are usually firmer but the best way to tell would be a genetic test against a known line and seeing how that progeny segregate.

The issue with an "orange" is simply whether or not the gene that makes orange t, which the most common form of an orange flesh, is present. How that outcome responds in a cross depends on whether or not that orange gene is masking a RR or rr background (ie if the orange genotype is R/R + t/t or r/r/+ t/t).

    Bookmark   June 4, 2009 at 3:52PM
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carolyn137(z4/5 NY)

The variety Dr. Carolyn, which is an ivory cherry mutated to a green when ripe cherry now called Green Doctors.

Mulio explained the genetics of that to me several years ago when this mutation first occurred in someone else's garden but although I have the explanation somewhere, the conclusion was that a so called white, none of which are really white, could mutate to a green when ripe.

The question at the time was whether it was a cross or genetically stable due to spontaneous mutation, but it's been completely stable since it was found.

Carolyn

    Bookmark   June 4, 2009 at 4:13PM
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spiced_ham(z5 OH)

One of my accidental Lime Green Salad crosses is possibly with Dr Carolyn. I have a fruit with two locules that ripened to orange with green gel. Does that outcome make sense? Other tomatoes in the vicinity were reds or blacks, and the other crossed plants are reflecting those parent yielding black, and orange ripening to red fruits.

    Bookmark   June 4, 2009 at 5:37PM
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mulio

One of my accidental Lime Green Salad crosses is possibly with Dr Carolyn. I have a fruit with two locules that ripened to orange with green gel. Does that outcome make sense?

not to me

you could get a yellow out of it but a true 'orange' doesnt make sense from those parents

maybe what you are calling 'orange' is really a yellow (golden yellow)

the link will show an example of a yellow with green flesh to the left. The two at left are yellows. The 'oranges' possibilities are all to the right. Be aware that some of those 'oranges' are not in circulation or heirloom backgrounds.

Here is a link that might be useful:

    Bookmark   June 4, 2009 at 11:04PM
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spiced_ham(z5 OH)

Yes, it looked very much like the first one in the row (gf, r), maybe a shade darker. One of my other LGS crosses ripened from green to that "golden yellow" and finally, slowly blushing to red, the flesh is light orangy red, sort of like a Juane Flamee that turned more red. I nicknamed it "Traffic Light". Zarnitza was the most likely pollen parent. I guess the different color genes kick in at different times during ripening with that one.

Another quick question. Relatively speaking, how many of the popular golden/orange heirlooms get their color from Tangerine, or B, and is there a way to tell which it is by the way the color develops?... or taste? I don't like some of them because of a subtle pumpkin tone to the flavor.

    Bookmark   June 5, 2009 at 7:29AM
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mulio

Another quick question. Relatively speaking, how many of the popular golden/orange heirlooms get their color from Tangerine, or B, and is there a way to tell which it is by the way the color develops?...

Probably all get their color from tangerine. The notable exceptions would be 'Caro Rich' and 'Caro Red' and the Cheeseman ones.

The others come from other species or are unique mutations which never found their way into release.

They do taste different but it wouldnt be a good way to tell them apart. Again they are classified by analysis of the carotenoids. Tangerine often has a subtle organish color to the anthers.

    Bookmark   June 5, 2009 at 11:41PM
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spiced_ham(z5 OH)

Thanks again

    Bookmark   June 6, 2009 at 7:06AM
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