[Tom Wagner]

Hilde,



You have a lot of questions, but I don't think anyone can fully explain less making a complicated study yet further complicated.

.....the gene list is confusing, it doesn't tell me what traits are dominant or recessive or partially dominant or recessive. Maybe I have overlooked something, but I can't seem to see where that is.

Patience is required with genetics!

I am growing out some tomatoes that has the temporary name Kelloggs Breakfast Heart F2. Mark Korney grew the F1, which was supposed to be Kelloggs Breakfast, but produced red heart shaped fruit on a RL plant.

OK. I know that Kellogg's Breakfast is a regulare leaf, pale orange fleshed tomato with no bi-coloring.

The heart shape must be coming from the other parent. The genetics does not necessarily mean that the other parent is red!!!!!

I sowed 21 seeds and got 50/50 RL/PL seedlings. This suggests as far as I know that KB has PL in it's background (Cc) and was crossed with a PL variety (cc). My interest in tomato genetics now exploded, but I can't seem to find answers to all my questions anywhere!

I am not sure where this high of percentages of phenotype of potato leaf is coming from. Where are you coming up with the idea that KB has PL in it's background? See this link:

http://www.victoryseeds.com/catalog/..._breakfast.jpg

The little I know is:
Yellow skin is dominant to clear skin.
Red color is dominant to yellow color.
Regular Leaf is dominant to Potato Leaf.
Small size is partially dominant to larger size fruit.

Correct so far

I wonder about things like: Where does Orange fit in here? Is it considered a variation of yellow?

Depends on which orange gene you are talking about.

How about shapes? What would be dominant of heart, globe, beefsteak, elongated plum, irregular shapes just to name a few?

A few? Good Grief? I could not spend the time to show the dominant, incomplete dominance, etc., without writing the book.

Where does bicoloration fit in? If you cross a bicolor variety with a single color variety, how would the offspring be?

You don't want to know much, do you?

If you cross a tricolor variety with a bicolor variety, how would that offspring be?

You want an answer on that too?

Also, within the main colors: If you cross a pale yellow (white) variety with a warmer yellow variety (For instance Hugh's x Azoychka), would the warmer yellow be dominant to the pale yellow?

To get the answer to that, you would have to visit my tomato trials with all this diverse crossing work going on, with F-1 hybrids, backcrosses, F-2's, three way crosses, etc.

Where does the gene that causes the green-when-ripe varieties to stay green fit in?

I have all of that.

What happens if you cross a det. variety with an ind. variety?

You get mostly a strong semideterminant, but not always.

Talking about gold/red bicolors, I have some Cherokee Bicolor from Mark growing in the green house. From two different mother plants. I believe they are F3.

There are different patterns of bi-colors. You really don't want me to describe all of them, do you?

How come there is so little known about the genetics of bicolors? Has there been little research on this or is this just particularly difficult to find out of? I just assumed that I would get all gold/red bicolored cherokees, but maybe not?

Bi-colored tomatoes have exploded in popularity in the last few years. And most of it by hobby type gardeners leading the way. The professionals have not kept up. Try to put together a Punnett Square with multiple alleles and describe phenotypes in the segregation, let alone realize that some bi colors designs are best viewed in lines that will still segregate

Is bicoloration dominant or recessive to single coloration?

I would have to dig out all kinds of examples of my hybrids with the notes taken down over the years. I even get confused on this topic.

I am having a lot of fun here, and part of the fun is learning about tomato genetics and speculate to whatever will show up in the crosses and offsprings. I don't have any illusions that I know it all, genetics can be very complicated. Genetics is more complicated than one would perhaps think.

Hilde, thanks for saying that.

Some observations: First go to this site....


http://www.genetics.org/cgi/reprint/...urcetype=HWCIT


The F1 hybrids red X apricot, yellow X apricot, yellow-tangerine X apricot and
tangerine X apricot were red in color, but as can be seen from table 3, the lycopene
content was not always within the range of a typical red,



Dave mentioned the genetics.org's large info site. See below for a 1937/1953 era reference...


http://www.genetics.org/cgi/reprint/38/2/117.pdf

1937)
Cites correspondence with MACARTHUR which the latter suggested that
crosses involving Tangerine orange (RRtt) and yellow (YYTT) produce a
9 red : 3 yellow : 4 orange (3 orange and 1 light orange) F2 ratio. From their
own data, however, these authors suggested that the inheritance was considerably
more complicated.

Monohybrid segregation is always a first start of explaining genetics...
http://en.wikipedia.org/wiki/Monohybrid_cross

Monohybrid cross is used to determine the F2 generation from a pair of homozygous grandparents (one grandparent dominant, the other recessive) which results in an F1 generation that are all heterozygous. The pairing of these offspring results in a monohybrid cross and results in the F2 generation, with a 75% chance for the dominant phenotype and a 25% chance for the recessive phenotype.

A dihybrid cross is one where two traits are crossed.

Phenotypic Ratio

9

3

3

1

Note the segregation of MacAthur’s Tangerine/Yellow cross earlier in the segregation of phenotypes

Trihybrid Cross (three genes)

Segregation in the F-2 population depending on allele counts.
Monohybrid phenotypic ratio= 3:1
Dihybrid= 9:3:3:1
Trihybrid= 27:9:9:9:3:3:3:1
Tetrahybrid= 81:27:27:27:27:9:9:9:9:3:3:3:3:1

You notice a pattern here? The more a trait is controlled by multiple genes at different alleles, the more confusing the blanket statements on bi-colors, etc. can be. The F-2 and even to some degree the F-3 population is showing phenotypical disorder. One must know from experience when something is stable or not, and that may be an exercise of trial and error for most of us.

The major problem I have in bi-colors is that I need more time and more plants to establish ratio coordinates. When I most often have only one or maybe six plants in an F-2 or F-3 population, I cannot answer as certainly as a Three Stooges character.

Tom Wagner
BTW, forgive my ramblings.