An interesting breeding possibility

[Tania]

Cool - thank you Andrey, I will read it up. Can you give a link to the original?

[Andrey_BY]

Always welcome.

http://sad-sib.ru/pub_88.htm

[Fusion_power]

Andrey, reading between the lines, 1 plant (cucumber?) on 3 hectares was cold tolerant. That would indicate 1 single plant out of about 20,000 was able to survive a severe freeze.

I found a small number of plants from one single variety of tomato were cold tolerant because they were exposed to 22 degrees (-5C) overnight in 2007. I also lost about 5000 tomato and pepper plants that night though there were several peppers that showed some tolerance.

I have reason to suspect that our domestic tomato will show very little cold tolerance. This should explain my interest in the S. Lycopersicoides introgression lines. S. Lycopersicoides happens to be adapted to tropical mountain climates at altitudes up to 3600 meters (2 miles) where temperatures routinely drop to the range of 0 to 10 degrees F (-13C to -18C). It seems probable that it would have genetic adaptations specifically for perennial survival at such temperatures. Working with the genetics will be extremely difficult because this species is so genetically distant from tomato. The introgression lines will make it a lot easier for breeding work, but teasing apart the genes involved will take many plant generations of breeding work.

DarJones

[Andrey_BY]

Darrel,

yes, he has found only 1 tomato plant survived after a frost in this field, but you have to imagine that there was no a big diversity of tomato varieties that times in USSR

And I know he has started these experiments in late 1930s-1950s when they had not so many opportunities for a passionate amateur breeder in Soviet Union to grab any info about many things concerning genetics (except from old Russian Genetic books) or to use special methods. He was a common teacher at the school and his pupils often joined him in his passion.

Now you are fortunate to try many things (including access to other lines from another species) to get on a higher level and use your knowledges of modern genetics. I wish you good luck and will be glad to try your future samples of cold tolerant varieties.

[Fusion_power]

I'm laying out the objectives for this cold tolerant tomato. I am going to incorporate breeding lines with red, pink, and black fruit colors and will not use white, yellow, or orange because of difficulties with flavor. I see three significant high level objectives and hurdles.

The first is foliage tolerance to cold temps, in other words, does not freeze. This trait would be useful in both early and late season, but would be most effective for spring planting prior to settled warm weather. This trait will be the highest priority since it is already available in some lines.

The second is fruit tolerance to cold. Since tomatoes are mostly water, I expect this will be a very difficult objective. I expect this trait will come from one or more wild species because I can not find any reference to such tolerance in domestic tomatoes. I have observed volunteer S. Pimpinellifolium plants in my garden that produce fruit that are not damaged down to 25 degrees so the outlook for this trait is very good.

The third is to develop a very good flavored tomato that maintains high eating quality even when fruit mature at low temps. I think this trait can be incorporated in combination with both of the traits listed above, but I will note that even a moderately good flavored tomato would be a major achievement given the current status of available varieties.

A. must be able to tolerate extremely low temps (Fahrenheit) to be scored for the following temperatures: 28°, 25°, 22°, 15°, 0° where:
1 = foliage unaffected, no frost damage
2 = foliage lightly affected, frost damage minimal
3 = foliage minimally affected, light to moderate frost damage, plant growth minimally slowed down
4 = foliage significantly affected, up to 50% of foliage with frost damage
5 = Major leave damage, plant unlikely to recover

B. Fruit must be able to tolerate freezing temps scored for the same temps as:
1 = no frozen fruit, no water blemishes
2 = no frozen fruit, minimum water blemishes
3 = no completely frozen fruit, some water freeze damage blemishes
4 = some fruit frozen, significant water freeze damage
5 = Most fruit damaged, watery, inedible

C. Flavor must be maintained both as a summer crop and when matured at average temps below 45°. I am setting the bar very high for flavor, I will set Eva Purple Ball as 5 - mediocre summer flavor for the standard!
1 = Excellent summer flavor, Excellent cool season flavor
2 = Excellent summer flavor, Very good cool season flavor
3 = Very good summer flavor, Good cool season flavor
4 = Good summer flavor, Mediocre cool season flavor
5 = Mediocre summer flavor, Poor cool season flavor

Here are the genes and traits I want to incorporate and the rationale behind each:

1 - Jointless - this will allow fruit to be picked without stem punctures
2 - High Lycopene, high vitamin C, high vitamin A - enhances fruit $ value and adds nutrition value
3 - Size - to be defined as approximately 2.5 to 3.5 inches diameter fruit (Eva Purple Ball)
4 - Fruit to be round, not oblate - This will give more leeway when introgressing traits from wild species which tend to be round
5 - Precocious flowering - This trait is significant for early fruit maturity
6 - Fruit maturity in 65 days - This trait enables early season harvest, we want good flavored tomatoes EARLY
7 - Balanced flavor - Not sour, not tart, rich tomato essence with just the right amount of sugar
8 - Highly disease tolerant - Some of the genes desired are ph0, ph1, ph2, ph3, ph5 (late blight), I1, I2, I3 (fusarium), sw5, sw7(tomato spotted wilt), mi1, mi9 (nematodes), tm2 (tobacco mosiac virus), sm (stemphyllium), cf1, cf2, cf4 (cladosporium), (septoria), (early blight), (bacterial spot), (bacterial wilt), (other viral tolerance, tylc, etc)
9 - Heavy production - I have a line derived from a cross of Big Beef X Eva Purple Ball that will be the model
10 - Widely adapted - Must be capable of growing and producing over most of the U.S. and Canada


Some nice to have traits would include ability to set fruit even at temps over 100°.

I will have to evaluate plant form to determine which makes the most sense. I have seed of varieties with indeterminate, determinate, dwarf rugose, ultra dwarf, and brachytic plant habit.


Varieties I plan on growing to see what can be done:
Kimberly X Eva Purple Ball - to move the precocious flowering gene into a larger fruited variety
(BBxEPB) X LA4026 to combine jointless, high lycopene, F1, F2, F3
LA4454 X Druzba to combine the sucr gene with a good flavored line
Tastiheart X LA2006 to combine cold tolerance with fruit set at 40°F
Perth Pride X (disease tolerant breeding line from R. Gardner) to get ph3 into a dwarf
Doublerich X LA0722 to move the ascorbic acid gene(s) into a high vitamin A line

I'll have to work on this more later. The above is a preliminary outline and will have to be adjusted to fit circumstances later.

I would love comments of other traits you think are important or critique of the above plans

DarJones

[Diriel]

To set fruit at or over 100 f. would be fairly awesome in itself. The cold tolerance, of course, will be more than welcomed.

I think a dwarf rugose would be nice. Perhaps even something along the lines of a semi-dwarf rugose? Will the root system will be considerably bigger and more aggressive than your average domestic tomato?

This project definitely has my attention.
Gary

[Redbaron]

I think split resistance is almost as important as disease resistance. I don't know if the trait is linked in any way to any of the traits you listed. I also don't worry too much about it myself. A knife easily trims the "scab" of a split area off before eating. But I have noticed that outside of people really into tomatoes, that is the primary "off putting" thing about heirlooms or otherwise great tomatoes.

Also there is a gene in fruit I read about. It is a specific gene for green shoulders. Increases the sugar and nutrient balance in the fruit many times over. (sorry I forget the name of the gene)

That I think would be useful in making sure the fruit are as frost resistant as the plants. It also is helpful in maintaining flavor late in the fall.

[Fusion_power]

You are thinking of the ug gene. It causes fruit to be a uniform gray/green color. The advantage of this gene is that fruit ripen evenly and don't have green shoulders. The disadvantage is that fruit flavor is reduced. However, there is a LOT more to tomato flavor than just this gene. I will be deliberately selecting against this gene i.e. selecting for the standard type present in most heirlooms.

Re cracking and splitting, so far, I have not included any crack prone varieties. But I do have Burgess Crackproof which could be easily incorporated to eliminate this problem if it occurs. I would also point out that Druzba and Eva Purple Ball rarely crack or split. This also brings up the question of whether thin skin or thick skin is to be selected for. I would prefer to be intermediate, not too thick, not too thin.

Fruit size is also important, if I were selecting for large fruit with the fasciated gene, then catfacing and deformed fruit would become a problem. Since I am targeting a round fruit in the 2.5 to 3.5 inch range, I won't have to worry about this problem.

DarJones

[Redbaron]

Originally Posted by Fusion_power

You are thinking of the ug gene. It causes fruit to be a uniform gray/green color. The advantage of this gene is that fruit ripen evenly and don't have green shoulders. The disadvantage is that fruit flavor is reduced. However, there is a LOT more to tomato flavor than just this gene. I will be deliberately selecting against this gene.

Re cracking and splitting, so far, I have not included any crack prone varieties. But I do have Burgess Crackproof which could be easily incorporated to eliminate this problem if it occurs. I would also point out that Druzba and Eva Purple Ball rarely crack or split. This also brings up the question of whether thin skin or thick skin is to be selected for. I would prefer to be intermediate, not too thick, not too thin.

Fruit size is also important, if I were selecting for large fruit with the fasciated gene, then catfacing and deformed fruit would become a problem. Since I am targeting a round fruit in the 2.5 to 3.5 inch range, I won't have to worry about this problem.

DarJones

Yep that's the one. I got it backwards. It is the LACK of a UG gene that makes for dramatically higher sugar content. I mentioned it primarily because Sugar in plants is an antifreeze. My collards don't even get real tasty until after a few good frosts. So trying to develop a freeze resistant variety at the same time as including the UG gene may possibly be fighting against yourself as far as the fruit goes. Not sure if the varieties you are starting with have the UG gene or not?

As far as the 100+ temps go..it might be too much to ask to have them tolerant to both freezing AND high temps, but I suppose it is possible. In any case if you need a growout looking for the heat tolerant gene. I can guarantee Oklahoma summers are PLENTY hot enough 110 is common, and yet we still get early freezes here too. Every year we have temps in the 90's followed soon after with frosts. Just a few days ago we had temps in the 80's and the weatherman predicts snow Monday????.

[Diriel]

By the way, what about "keeping qualities" both on the vine and on the counter top?

[Fusion_power]

I thought about "keeping qualities" too, but have not put enough effort into it yet. I was mulling using Piennolo del Vesuvio as a model for a long term storage tomato, but it has a very thick skin which seems to be necessary to prevent moisture loss. There is also a possibility of using sugar accumulation to stabilize a tomato for long term storage. Plant sugars can be hygroscopic under some conditions so it is possible that some selection work could identify a tomato that would store longer because it is sweeter. Longkeeper is not bad as a tomato, but the way it works is by modification of one of the ethylene genes. I'm not sure that would be a good idea since monkeying around with ethylene rapidly degrades flavor.

DarJones

[Diriel]

To be honest, a thick skin does not bother me overly much. That being said, I do like your preference for a mid point in skin thickness.

[Diriel]

Thank you for the heads up on the Piennolo tomato. I just added that to my must grow list.

Gary

[Fusion_power]

I've done some more serious studying on the traits required to breed a cold tolerant tomato. One of the basic problems to overcome is that most tomato plants do not flower below about 60°F and as the temperature drops further the leaves lose efficiency, the roots become ineffective at absorbing potassium and phosphorus, and leaf chlorophyll tends to drop causing the leaves to become distinctly yellow. I'm going to presume that each of these traits can be addressed.

The CBF pathway is the basic cold sensitive biopath that allows a plants in the tomato family to respond to cold temps. From one of the articles that ChrisK posted in the Winter Reading thread, this pathway can be ramped up by a cross with LA3969 which is an introgression line containing part of chromosome 12 from S. Habrochaites. I have therefore asked TGRC to add this line into my shipment.

The root efficiency issue is going to be difficult. I have not found any documentation showing increased root efficiency at low temperatures for any known lines of tomato. I am going to lean heavily on the S. Lycopersicoides IL's (introgression lines) to provide some genetics to address this. I will also have some other possibilities from seed which Frogleap sent me of an L. Peruvianum line that seemed to have significantly improved root strength and structure.

There are two distinctive high level traits that I must improve to develop a cold hardy tomato. One is the ability of a tomato plant to continue growing at low temps. The other is the ability of foliage to withstand overnight freezing temps. The two traits are complementary, but not necessarily linked. I will therefore have to take some special steps to identify plants that exhibit both capabilities.

My first thought was to simply place some plants outside when the temp is going to be between 32 and 55 degrees. But I can't control these conditions well enough to really tell a difference. So my second thought is that I can set up a shelf in my refrigerator to place plants so they will get about 12 hours at 36 degrees and then be placed under lights for 12 hours at 72 degrees. If continued several days, this should result in some plants showing an ability to grow even when regularly exposed to low temps.

The next issue is to find a way to test plants at freezing temps. I can easily pick a night when the temperature is going down to about 25 degrees to put the plants outside. The problem I foresee is that frost will form on the leaves which will kill them. I want to find plants that will withstand freezing temps, which does not necessarily mean that the plants can also stand having frost form on the leaves. If the wind is blowing, then frost does not normally form. If the plants are covered with floating row covers, then the frost forms on the row cover but not on the plants. Another option is to turn my refrigerator down so it hits 25 degrees and equip it with a small dehumidifier to prevent frost. With a setup like that, I could completely control the conditions the plants are exposed to.

There is lots more thinking and planning to do and quite a bit more reading of articles about cold tolerance and tomatoes.

DarJones

[Tania]

Fascinating reading and what a project!!!

Darrel, I am so looking forward to hear your further thoughts and learn from you.

Tatiana