Hi. Does anyone know of a good resource listing tomato genes and their dominance, linkage, etc.? I'm interested in starting a first-time tomato breeding project this summer and could use a few pointers. I already have an old Soviet ultra-early, short, rugose, tree stem determinate that I like the qualities of and want to keep with the exception of introducing the tangerine gene. The tangerine donor that I have in mind is an indeterminate. As I might have mentioned in my introduction, I'm a Biologist with a good working knowledge of genetics, but new to plant breeding. I'd be grateful for any feedback or information that might help me get started.
Debbie
https://tgrc.ucdavis.edu/Data/Acc/dataframe.aspx?start=GenSearch.aspx&navstart=nav.html
https://tgrc.ucdavis.edu/Gene%2520list.xlsx
https://www.google.com/url?sa=t&source=web&rct=j&url=https://tgrc.ucdavis.edu/Gene%2520list.xlsx&ved=2ahUKEwjagoCusP7mAhUNG80KHXaLCSIQFjABegQIAxAB&usg=AOvVaw34YCG7gpUxyQVBvOf-czRi
Sounds kind of like Krainy Sever. Nice upright early keeps the fruit off the ground.
All the earliest are boring red. I like the idea of changing that.
I have an Amurski Tigr cross in yellow as of last year.
Thank you. This is the kind of information I was hoping to find. My tomato definitely isn't Krainy Sever, but may have similar breeding. Unfortunately it came without an original name, so I don't know. From the links, it looks like there are quite a few mutations that result in dwarf phenotypes...
Debbie
To introduce a single recessive trait you can make recurrent back-crossing with a two-years selection (to recover the recessive t allele)
I want to keep the dwarf's growth habit and other characteristics, so I'm not sure I want to back cross to the tangerine. If dwarf/rugose is dominant, I was thinking of using the dwarf as the pollen donor so that I could visually confirm hybridization and then mass sow the F2 seeds and rouge out any non-dwarf and non-tangerine flower colors. Then (theoretically) I'd be left with only t/t plants and looking for stable dwarfs that most closely resemble the original strain in size, earliness and productivity. Does anyone know if determinant dwarf/rugose traits are dominant to regular leaf indeterminant?
Debbie
The dwarf is your recurrent parent. You cross Dwarf x tangerine (or the other way) one time, and then you select among F2 one with tangerine fruits, then backcross to your dwarf, then select again among your second generation and then backcross, and then select ...
Quote from: Debbie P on 2020-01-20, 08:36:40 AM
I want to keep the dwarf's growth habit and other characteristics, so I'm not sure I want to back cross to the tangerine. If dwarf/rugose is dominant, I was thinking of using the dwarf as the pollen donor so that I could visually confirm hybridization and then mass sow the F2 seeds and rouge out any non-dwarf and non-tangerine flower colors. Then (theoretically) I'd be left with only t/t plants and looking for stable dwarfs that most closely resemble the original strain in size, earliness and productivity. Does anyone know if determinant dwarf/rugose traits are dominant to regular leaf indeterminant?
Debbie
Dwarf is recessive. not sure about determinate.
GM
Dwarf, determinate and tangerine are all recessive.
The way to do this without growing 64+ F2, grow as many F2 as you can and save seed from all the ones that show any one or two of your recessives. You can cross these siblings with one another in the F2 or in F3 or later, to increase your ratio of missing recessives in combination. This is really the only way to maximize your ability to select for other traits like fruit quality, plant health etc. without growing thousands of plants. If it takes 64+ (expected) to find one plant with the 3 recessives, there is a bottleneck on your other traits that can put a limit on future selection, if for example desired taste traits, plant health, earliness or other, are not there in that single F2 plant.
One handy thing about the dwarf with rugose leaf, you can identify these when seedlings are quite small. That means in any generation you want to do a broad selection for that trait, you can grow masses of seedlings and just cull all the non dwarves right off the bat.
Determinate doesn't have a good 'tell' at the seedling stage, especially in det X indet, expect to get a really big variety of growth habits and leaf/cluster patterns. I have seen F2 determinates that grew just like an indet and then produced the terminal bud after 7 or 8 regular pattern (3 leaf nodes between clusters). Also the number of leaf nodes before the first cluster is a genetically separate trait from indet/det. As also the QTL(s) for internode length.
The dwarf trait may tend to shorten internodes in heterozygous plants, where the rugose leaf is masked.
Make sure of your tangerine parent, in case you didn't know, there are several other genes that produce orange fruit. Beta orange is quite common. These genes are unrelated to the tangerine gene, and behave differently. tangerine will only show up when homozygous, afaik it is completely masked in heterozygous state.
Great project! :)
Quote from: Steph S on 2020-01-23, 08:06:39 AM
Dwarf, determinate and tangerine are all recessive.
The way to do this without growing 64+ F2, grow as many F2 as you can and save seed from all the ones that show any one or two of your recessives. You can cross these siblings with one another in the F2 or in F3 or later, to increase your ratio of missing recessives in combination. This is really the only way to maximize your ability to select for other traits like fruit quality, plant health etc. without growing thousands of plants. If it takes 64+ (expected) to find one plant with the 3 recessives, there is a bottleneck on your other traits that can put a limit on future selection, if for example desired taste traits, plant health, earliness or other, are not there in that single F2 plant.
One handy thing about the dwarf with rugose leaf, you can identify these when seedlings are quite small. That means in any generation you want to do a broad selection for that trait, you can grow masses of seedlings and just cull all the non dwarves right off the bat.
Determinate doesn't have a good 'tell' at the seedling stage, especially in det X indet, expect to get a really big variety of growth habits and leaf/cluster patterns. I have seen F2 determinates that grew just like an indet and then produced the terminal bud after 7 or 8 regular pattern (3 leaf nodes between clusters). Also the number of leaf nodes before the first cluster is a genetically separate trait from indet/det. As also the QTL(s) for internode length.
The dwarf trait may tend to shorten internodes in heterozygous plants, where the rugose leaf is masked.
Make sure of your tangerine parent, in case you didn't know, there are several other genes that produce orange fruit. Beta orange is quite common. These genes are unrelated to the tangerine gene, and behave differently. tangerine will only show up when homozygous, afaik it is completely masked in heterozygous state.
Great project! :)
I applaud this reply. Best plant breeding advice for stacked recessives! If you follow this plan I can't see how you can go wrong!