Varieties with Color genes

[frogsleap farm]

http://www.frogsleapfarm.blogspot.co...-color-in.html "Genetic Control of Fruit Color in Tomato".

I've been working on this on and off for a couple months. Some of the links are noted elsewhere in this thread, some are new. I've also added several photos from my nurseries the last few years.

[bower]

Fantastic, frogsleap! Very comprehensive review of the colour genes and such wonderful photos, your fruit are an inspiration, to say the least.

[Darren Abbey]

Frogsleep: Awesome! Thanks for doing the writeup, the awesome photos, and the tomatoes themselves!

[NarnianGarden]

Wow, awesome pictures and info! Thanks a bunch! Curiously looking forward to seeing exactly what colors I get from the plant you sent me seeds for...

[frogsleap farm]

Darren - I started this project late last year when I realized how little I knew about predicting the phenotype from F1 crosses I made from parents with various color combos. Your excellent blog on the topic gave me the energy to finally get my piece done.

[Darren Abbey]

Originally Posted by frogsleap farm

Darren - I started this project late last year when I realized how little I knew about predicting the phenotype from F1 crosses I made from parents with various color combos. Your excellent blog on the topic gave me the energy to finally get my piece done.

aw shucks.

Though I haven't done much tomato breeding (very little actually), the same uncertainty is what got me to start digging into the topic.

[NarnianGarden]

Most of what I read did go way over my head. Perhaps the article did explain but I did not get it: how would. let's say, two dominant traits behave - is there a way to predict that, or is it a random reaction?

[Darren Abbey]

Originally Posted by NarnianGarden

Most of what I read did go way over my head. Perhaps the article did explain but I did not get it: how would. let's say, two dominant traits behave - is there a way to predict that, or is it a random reaction?

It is easier to work out with regard to specific examples and then it depends on exactly what the genes are doing.
----

The wild-type allele 'R' is dominant and responsible for the red lycopene of tomatoes (the recessive 'r' leads to yellow/white tomatoes with no lycopene). Some orange tomatoes have a dominant allele 'B'/'Beta' leading to increased beta-carotene production, at the expense of lycopene.

It turns out that beta-carotene is synthesized from lycopene. For the dominant 'B' allele to be apparent with its orange color, there already has to be lycopene synthesis due to the dominant 'R' allele.

It isn't ever random, but without knowing how the traits interact it can be confounding.

[frogsleap farm]

Originally Posted by NarnianGarden

Most of what I read did go way over my head. Perhaps the article did explain but I did not get it: how would. let's say, two dominant traits behave - is there a way to predict that, or is it a random reaction?

At a single locus (gene) there is only one dominant allele. This is not always the case, but I believe it to be so with all of these genes. What complicates this story is that there are multiple genes involved, and changes upstream in the pathway (e.g) r or t that impact lycopene synthesis, will also trump B and Del, which convert lycopene to various forms of carotene. Simply if there is no lycopene there is no substrate for conversion to carotene. For the vast majority of tomatoes available commercially, just focus on the R, t and gf loci governing fruit color and Y governing pigmentation of the epidermis. Of course then there are stripes, anthocyanin, etc., which add another layer of complexity.

[Minnesota Mato]

Does anyone know if sungold has t or B ? my guess would be B but this is my first time growing it so I haven't had a chance to test it yet.

[Darren Abbey]

Originally Posted by Minnesota Mato

Does anyone know if sungold has t or B ? my guess would be B but this is my first time growing it so I haven't had a chance to test it yet.

That is one variety I've been curious about. It actually was what got me to start thinking about this topic.

Part of the way to figure it out would be to grow the F1 completely isolated and then grow out a selection of F2s. If all the F2s are orange, then it is caused by a recessive allele. If ~1/4 of the F2s have some other color, then it is likely to be caused by a dominant allele in one copy in the F1.

This is an experiment that several people have undertaken, though the reports I've come across are not consistent enough to be certain… but there is a mix of mostly orange and a few red/other. This is suggestive of a dominant allele, like B, but without strict isolation of the F1 parent, it is hard to be certain how meaningful the reports are.

Alternately, there are distinct differences in the carotenoid profiles produced under the influence of the different orange color genes and these can be identified using lab techniques that I don't know the details of how to do.

[bower]

If there are any records of Sungold crosses with red or yellow fruit, the F1 would be orange-red if it is Beta, and red if it is tangerine.

[frogsleap farm]

Based on several crosses and segregation in suceeding filial generations, I am pretty sure it is tangerine.

[Minnesota Mato]

If sungold is an F1 and tt then both parents are tt. Makes you wonder about its lineage.

[frogsleap farm]

I have several dozen new F1s that are just now starting to ripen. Several of these have a orange colored inbred parent tracing to Sungold or SunSugar. After looking at these hybrids this afternoon, I'm now thinking that the orange color in Sungold/SunSugar is dominant, either Del or B. I have some other unrelated orange lines that are tangerine, and some crosses that confound these genes - but it is starting to make some sense now.