Message Board - BigPumpkins.com

On top of Brush Mountain, Pa.

Interesting. Some of what is happening here with our tomatoes?
https://www.mariannasheirloomseeds.com/doctor-sine-s-corner.html

12/22/2017 8:20:41 AM

Oak Grove, Mn

Marv, you are going to have to explain this one to me. My current breeding plant..Step A- cross the 6.13 Zappa Brutus Magnum ( should be stable line) with my 3.96 from the Hunt Delicious( also should be stable). The resulting seeds are F1 should nearly all the same. What is the right terminology for these new F1 seeds. Step 2- cross the F1 Brutus Magnum x Hunt Delicious with seeds from my F2 MegamuttD. The megamuttD F1 was MegaDom F1 (Domingo x MegaMarv) x MegaZac F1(Big Zac x MegaMarv). So what is the proper identification for the new very unstable cross=F1XF2(F1 xF1). The mixture of step 2 is 25% Brutus Magnum, 25 % Hunt Delicious, 25% Megamarv, 12.5 % Domingo and 12.5% Big Zac. I don't think the competition growers that are capable of crossing are going to take the generations to grow them out to stable. Depending on timeline for successful crossing..I will be either growing about 10 plants from step 1 or step 2 this summer. The best two to four will be put back into winter breeding stock. If I would grow this out to F6 or better taking the best of the grow outs..the percentage of the different varieties will change, depending on which gene combination produces the best. I will not know which variety is becoming more dominant in the the resultant seeds. I think we have entered an era of new territory in competition giant tomatoes. Hypothetically...if i grow out two plants that were both grown from F1 seeds that were (F2xF2) x(F2xF2) or something similar...what should I put down for variety on GPC entry form?

12/22/2017 6:26:02 PM

Oak Grove, Mn

Further in this subject...the top weight of the genetic parentage of the stable varieties of this mixture is...6.13 brutus magnum, 7.33 delicious, 5.51 megamarv, 5.75 domingo, 8.41 big zac. Any of these seeds has the potential to be a competitive entry. Scrambling the genes and growing them out...there is a chance that 1% of the resultant combination could give us a new level of genetics to work with.

12/22/2017 7:40:01 PM

On top of Brush Mountain, Pa.

Here is the problem, at least as I see it. If you take all of the F1 seeds and plant them the plants resulting should all look pretty much alike and none of them will exactly look like their individual parents. If you plant the seeds of the the F1 plants seeds you will begin to get lots of variability as the F2 seeds are unstable. If you cross the F2 you will have even less of an idea of what you have. You need to stick with growing out these crosses and selecting tomatoes that you like for seeds, those that have the characteristics of what you want, like big. If you keep crossing you will lose all hope of predictability. Seeds don't stabilize at least until F5. To create a new reproducible seed you make a cross and then grow that cross out while selecting for the characteristics you want. If the F1 seeds of the cross give you nothing good, I would probably stop there and try a different cross. Just my thoughts. If Thurber is looking maybe he will chime in.

12/22/2017 8:46:49 PM

Oak Grove, Mn

Marv....if we look at what the pumpkin growers have done. If we have looked at what the pumpkin growers have done..they are always growing out F2xF2. And regrowing the biggest results. The genetics of pumpkin potential has increased immensely from the unpredictable results. Tomatoes are a bit different..really easy to get high F numbers. But is this the right plan. Most growers to get F5 takes 5 years. Yes, you can make a better prediction of what you will get. If you are crossing the best F2xF2 twice per year...is it not possible the genetic potential can expand at 10 times the rate of controlled breeding of stabilized variety..sure there will be duds..but I am of the opinion that best f2 crossed with the another best f2 will bring higher weights long term.

12/22/2017 9:13:36 PM

Garden Rebel (Team Rebel Rousers)

On top of Brush Mountain, Pa.

I am not knowledgeable enough to know for sure. The problem is that what the F2 will grow is unpredictable. So if you cross 2 F2s you are crossing two unpredictable seeds. Only fantastic luck would give you the outcome you would be seeking. Anyone want to chime in?

12/23/2017 8:57:49 AM

Lebanon, Oregon

Yes, interesting filial article. I always wondered what the "F" stood for. I like low filial surprises and the unpredictability. A big surprise like MacCoy and Sutherland is the goal. That is why I plant over 40 plants. If my seeds were predicable I would only plant 5. Although this thinking of crosses is interesting, it is best left for a tomato grower savant. There is too much variability in the average big tomato growers garden to grow anything out to a predictable F5. We all have the capable seeds to grow a world record. Bnot, you have the genetics. Most of the AG growers have the genetics. I can have the same AG seed as Ron Wallace but don't go through the paces that he does to ever grow a world record. We have to hammer away at the techniques that make it so. The right surprise seed with the correct techniques and environment will grow a world record tomato.

12/23/2017 2:00:10 PM

Oak Grove, Mn

Marv..if you are going to rely only what the F1 generation produces you are limiting yourself. If the size determinate genes are smaller but dominent in the F1, you will have a smaller tomato. It is only until F2 that the recessive size determinate genes will show..and only on 1/4 of the plants. Same with all the rest of the characteristics. That is why I think crossing the top 25% of F2's is the way to breed. You then are getting the top of both dominant and recessive. If I get a chance to put my ideas to words..I will try to write it up and email it to you. I would love your input and reasons why my theories are wrong. Hopefully by the first of the year I can get something together to send to you.

12/23/2017 4:51:08 PM

On top of Brush Mountain, Pa.

Bnot: Most of the seeds we are now growing are F5 and beyond. They are stable. The big Hunt Delicious and all of the seeds through Boudyo are all stable. Also Domingo.

12/23/2017 5:48:34 PM

On top of Brush Mountain, Pa.

Take a look at this and try to imagine what the seed would be like if you crossed two F2 plants.

http://kdcomm.net/~tomato/gene/genes2.html

12/23/2017 6:13:19 PM

Oak Grove, Mn

I looked at the site...We need more colors. We need light green dark green and light blue and dark blue to show the relative dominant-recessive characteristics to opposite color. Some varieties in F1 might be all dark or all light. Lets make the same chart with 100 % gene dominance green..100% gene dominance blue and 50% equal dominance green/blue. Then lets cross the F2's and see what we have. Then grow out the top 25% F1's to F2's. These charts are simple...we are extreme growers...we can go beyond this.

12/23/2017 6:54:04 PM

Farmer Brown (Chris Brown)

Oak Grove, Mn

1/2 hour more thinking...we not only need to make these charts to show..dominant/recessive charaterics..but we need to show best gene potential...whether it is dominant/recessive...maybe we can add stripes to the picture. Too bad I don't have more time...i could make a chart...with 2 colors, two shades and a stripe...and show the effect of crossing F2's with all ranges of possibilities.

12/23/2017 7:23:50 PM

Zimmerman, Minnesota

So Bnot would your 1109 Borgers be like an F5 because you keep selling it?

12/23/2017 8:56:59 PM

East Carbon, Utah

Let's see, we had some interesting conversation about this topic a couple of years ago on The Tomato Depot, but without going through the probabilities or in-depth consideration of heterozygous vs. homozygous genetic states.

By no means am I an expert geneticist, though I did teach college biology and related courses for a few years, including units on basic genetics. Three broad categories make a species a good candidate for breeding if the purpose is to reveal principles of inheritance:

1) Short generation time (think fruit flies or bacteria)
2) Cheap and easy to produce hundreds, if not thousands of individuals for determining phenotypic traits.
3) Multiple traits that are obvious in terms of phenotype (think Gregor Mendel's peas - green vs. yellow seeds, purple vs. white flowers, etc.)

Note that in the realm of growing giant tomatoes, NONE of these categories apply.

1) Tomatoes have a 1-year generation cycle, unless we collaborate with growers in the Southern Hemisphere, as was done with the Dwarf Tomato Project.
2) Do any of us have the time, resources and patience to grow 500 tomato vines per year, all under identical conditions, in order to obtain the quantity and quality of data needed to obtain rigorous, scientifically valid results?
3) With giant tomatoes, we are dealing almost exclusively with regular leaf, indeterminate vines and red-fleshed fruits. We do have some observable outward variation in terms of: clear vs. yellow epidermis; ribbed vs. not ribbed fruits; degree of fusing of ovaries (think Big Zac vs. Domingo); some texture and flavor differences. But most of the genetic variation that we are concerned with is simply ultimate weight of fruits; any other apparent phenotypic traits are functionally superfluous. The genetic diversity we are interested in is largely not readily observable.

12/23/2017 9:47:37 PM

East Carbon, Utah

The blue/green plastic egg illustration is excellent for giving a basic understanding of how genetic inheritance works over time from a single cross for a single trait. This illustration might very well work for the single trait of potato leaf vs. regular leaf inheritance in tomatoes.

But with fruit size, we are likely dealing with multiple genes, and potentially several alleles of some of those genes. And these genes could be influencing a variety of metabolic processes that are far from obvious at the phenotypic (visually observable) level. For example:

• Ability of roots to work with mycorrhizal fungi in the uptake of nutrients
• Xylem tissue that is extremely effective at delivering water and minerals to fruits
• Tendency for ovaries to fuse in developing flower buds, thus producing (hopefully) super megablooms containing 10 or more ovaries
• Ability to prevent fruit from splitting during rapid growth
• Photosynthetic ability of leaves, stems, and even fruit
• Protein structures involved in metabolic pathways which transport calcium into cells

This list could get long!

Let's say our pool of candidates of tomato varieties for producing the first 10 (or 20...) lb. tomato is 20 - that is, 20 distinct, true-breeding varieties. Most of us here could readily distinguish the fruit, and to some extent the vine of MegMarv vs. Brutus Magnum vs. Big Zac vs. Domingo from outward, visual appearance (phenotypes). But are we observing the actual genetic traits (genotypes) that account for large size? The genes for skin color, ribbing, flesh color and degree/depth of lobing may have little to do with fruit weight. That is, they could very well be different genes, and may not even be linked with the genes for size - they could reside on different chromosomes.

12/23/2017 9:47:59 PM

East Carbon, Utah

More to the point, we cannot tell by visual inspection whether a fruit contains the best combination of genes for producing an exceptionally heavy tomato. All we can do is weigh the tomatoes, keep careful records of parentage, share that information with other growers, and be willing (hopefully anxious) to share the resulting seeds with other serious growers.

In practice, this means that it is largely not much of a concern whether we are dealing with an F2, an F4, or a pure-breeding line. Unlike most tomato purists, who want an open-pollinated variety which always produces fruits of the same size, color, flavor, etc., we are not so concerned here about consistency of such traits - we are pushing for large fruit size and not much else.

I'm not going to take the time to make a chart like the blue/green plastic egg illustration. But I think it's safe to assume that we are dealing with at least 30 alleles that influence large fruit size. These might occur at 12 different loci on 8 different chromosomes. Do we yet have the very best, unique combination of all 30 of the "best" alleles for producing the largest possibly tomatoes? Run the numbers - this is highly unlikely!

Thus the rationale and impetus for continued crossing, growing out, testing, and re-crossing: "Fresh new blood", so to speak.

12/23/2017 9:48:37 PM

East Carbon, Utah

I've mentioned several promising Russian varieties in other threads here. For generations, a large number of gardeners in Russia have been breeding for large fruit size. The chances are quite good that there are promising alleles in some of those varieties that are not found in any of the varieties which we commonly grow for competition.

I do like the strategy of continually crossing whatever seems like it may have some promise, then growing out the offspring for at least another 3 or 4 generations to see if something really special shows up. Again, even if we all pooled our efforts and had one massive, supervised "Giant Tomato Breeding Project", it would still be very difficult to seriously consider and test all possible combinations and permutations. We are talking hundreds of thousands, if not millions of plants every year.

A di-hybrid or tri-hybrid cross is complex and demanding enough; imagine trying to conduct and track a cross with, say, 12 genes simultaneously over 8 generations!

Others here will be much more familiar with the Tomato Genome Project than am I:

https://solgenomics.net/organism/Solanum_lycopersicum/genome

Ideally, we would have the funding and human resources to run DNA sequencing on the DNA from some of these more promising lines. Knowing exactly how Big Zac differs from Domingo (for example) at the level of the DNA code could really help point us in the right direction for selection and breeding. Short of this dream, I think the suggestion to take the lead of giant pumpkin growers is prudent. But I'll repeat what Marv has said several times: Please, let's all keep careful records of lineages and crosses, and keep that information with the specimens at every point from seed to offspring seed.

12/23/2017 9:49:21 PM

East Carbon, Utah

I've named a few of my F4 crosses among giant varieties after some hyper-giant stars. Naming at this stage would be premature if the goal were a pure-breeding tomato variety. But the primary, overarching goal is just heavy fruit; so some residual variation (12% or so for each trait that varies, according to the referenced article) is of minor importance, in my opinion.

Constantly researching and improving techniques is vitally important, of course; but I think it would very helpful, in the long term, if every grower could dedicated 20-25% of their growing space and efforts to testing out new varieties and crosses.

12/23/2017 9:49:43 PM

Oak Grove, Mn

Thank you Dale...that was really well written. Gives me much more to contemplate. I am looking at my breeding plants this morning and wondering if i should abort with this current group. This brutus magnum that should be stable variety, is not tossing a megablossom first truss. Even stable varieties will show some difference seed to seed. Unfortunately, I only have a few brutus magnum seeds. I agree with the difficulty of naming crosses. This winter is should have seeds from a F-4 wixom slammer(big zac x domingo). The F-4 that I get could be completely different than the F-4 of another grower. I suppose calling it Wixom Slammer bnot strain F4 would narrow it down. It is going to get more complicated..as I take the 5 variety crossed group..and grow, select,and cross. I have limited myself to 5 varieties..to do this with what dale thinks could be 20 varieties is an immense project.

12/24/2017 4:58:58 AM

Oak Grove, Mn

Farmer Brown...i think you are right...1161 F1, 1610 F2, 184 F3,356 F4, 1109 F5. Guess I am going to have to grow out the 1109 this year to get it to F6. It is unfortunate that Mike's 555 seeds were lost. There are not many stable pumpkin strains. Crossing unstable x unstable can still improve the genetics thru selective breeding.

12/24/2017 5:13:03 AM