Inheritance of ry (reddish yellow, ”bicolor”)

[Seven Bends]

Coming back to this old discussion about the inheritance of bicolour (ry).

I crossed a F3 yellow tomato from my Katie line (F2 in the pic left top) with a GWR bicolor tomato from my Aftershock line (left bottom) in the Spring and managed to just today harvest the F2 seeds from the F1 plant (right). Many of the F1 fruits are very ripe, some little less so. It seems that the bicolour expresses already in the F1 generation, as speculated earlier in this discussion. Interesting that the F1 is the reddish of them all. But maybe the pic little lies because the GWR bicolour is more on the underripe side and has clear skin and for this reason may look so much less reddish. In my experience so far, the amount of red in this bicolour line increases when the ripening progresses.

I suppose this also means that in such a cross the bicolour treat can be lost in later generations because the bicolour is here coming only from one parent. Which also means that the bicolour is easier to stabilize from a cross with non-yellow parent (like red or tangerine).

I can't contribute anything useful to the genetics discussion, but I just wanted to say that all of the tomatoes in your picture are really gorgeous! I realize this wasn't the point of your work and your post, but how is the flavor?

[Pippin]

@Seven Bends Thanks for asking, I was rather happy with the flavor. These are very small tomatoes, both the plants and the fruits, cannot compare with high brix indeterminate tomatoes though.

The GWR was very sweet which I think was contributed by the green shoulder gene. Not overly productive though. The yellow lines have sweetness too but are generally milder and have still a lot of variation. And the F1 was rather acidic but it does not really tell anything what to expect in the future because I am already off season with poor growing conditions.

[Toomanymatoes]

There is copy number variation in mammals without polyploidy, so I am sure it happens in plants too. Probably more so, since it appears to be related to environment.

https://www.genome.gov/genetics-glossar ... riation%20(abbreviated%20CNV,or%20include%20thousands%20of%20bases.

So, it is definitely within the realm of possibility that some tomato varieties have a single copy of the R gene/chromosome and others have multiples.

[bower]

I ended up growing one of my old cross parents this season by mistake (it was seed I started for the farm, mislabeled, and didn't realize until they ripened just what was going on) a yellow Zolotye Kupola. I remembered that it sometimes had a tiny bicolor blush, just a very weak amount of red which I discounted and considered it yellow. But this year there was a bit more blush on the inside and reminded me. I don't know how or why a bicolor would be so very weak. It couldn't be an inhibitor gene, because none of the offspring had any bicolor at all. Although I suppose not growing great numbers, it could have been there but I simply didn't find one. The F1 was red of course, so I missed the chance there. But maybe this is just a weaker allele for ry, which didn't show through in the F2 yellows and maybe that allele is less dominant than the one you've shown here.
Now I wish I had done the backcross to the determinate yellows.

[wykvlvr]

While I didn't get any crosses made this year I did grow Big Hill out and was impressed by it. The tomatoes are among some of largest I have had mature for me. The plants are small enough I could grow one inside during the winter. The flowers are larger then most tomatoes. The taste is very nice. And the coloring is downright beautiful like looking at a a sunset. My biggest complaint if you can call it that is most of the tomatoes were cat faced and misshapen.

[Pippin]

@Bower I remember seeing these very weakly expressing bicolours too, maybe some Dwarf Tomato Project variety, cannot remember now which. Seems very likeky that there are more than one ry allel. Or there are some other factors that impact the expression.

During this season I saw some blushing on what I have considered normal yellows. Didn’t really investigate them any further but I expect that the blush was on the skin or right below it. All blushing individuals had clear skin. Maybe there is still poorly documented skin bicolor gene too?

[bower]

@Pippin there is a lot going on in bicolor, I have no doubt, that is not well documented. I have not grown a lot of them nor worked with them before this year.
Just seeing Zolotye Kupola as a bicolor in what is obviously a light yellow fruit, raised questions about my own bicolor cross which is a much darker yellow if not a light orange background, as found in the bicolor parent Oaxaca Jewel PL.
I think we should continue this thread and explore the variation in bicolor to our satisfaction!

[Pippin]

Found this picture from the summer which shows some red blush on a ”white” tomato. This is an unstable line from a cross between a pink compact cherry and Cream Sausage (aka Banana Cream). The blush did not express on all tomatoes from the same plant but I think the more ripe they were the more certainly there was some blush. Many plants in this breeding line had this same behavior.

This is a clear skin tomato. I think the red blush must be in the flesh. Didn’t check though, cannot be 100 % sure. But if it was in the skin, it should have expressed more on as darker yellow splashes. I have considered this tomato as yellow (rr), not bicolor.

BABB2F22-29A9-4907-8A81-C0A4D0A154FB.jpeg

[bower]

bicolor-rumpus-F2-953.JPG

Just dug out these pics of the bicolor in my F2 this summer. Color is just like the OJPL parent.

bicolor-rumpus-F2-slice-827.JPG

[Frosti]

I didn't read the entirety of this thread, but I thought I might chip in with my experience of crossing with bicolor tomatoes:

This year I grew 2 lines of bicolor crosses. One that was crossed with "Orange Russian #117" and one that was crossed with "Blush". The female parents of both lines were unstable F2 dwarfs with red fruits (going by the results of this year, I presume they were both of genotype "Rr").

I grew 4 F1 plants of each cross. The expected frequency of bicolor and red fruits is 1:1.
"Orange Russian #117" cross:

bicolor_cross_or117.jpg

There was one plant that produced bicolor fruits (genotype rry) and 3 plants that produced red (genotype Rry) fruits.

"Blush" cross:

bicolor_cross_blush.jpg

3 plants with bicolor fruits (don't mind 2-22, I assume its lighter coloring can be blamed on a different growing location. The other plants had A LOT more sunshine) and one with red fruits.

Given these results, I'd assume the hierarchy is R > ry > r.

[bower]

That's some good sleuthing @Frosti . Very clever to use the Rr as a parent and see how the three alleles play out in F1.