An interesting breeding possibility

[Diriel]

Do you know any florists? Better yet do you know any restaurants? A restaurant will have both a walk-in Refer and walk-in Freezer.

The special Florist evaporator coil is made especially for keeping cuttings in a healthy type of low-ish temp setting. However it does not provide a freezing temp possibility I do not think.

Gary

[ddsack]

Great project, Fusion! Thanks for posting that complex and thought provoking information. Makes me appreciate how difficult it really is to develop a tomato for specific stable traits.

[goodwin]

Dar - some interesting research which you may already have come across:
http://www.scielo.cl/scielo.php?pid=...pt=sci_arttext
I'm thinking of using Koralik as well - very strong multiflora set under low light and cool conditions.

[Redbaron]

That looks like a determinate fruit set on a multi flora? I haven't grown anything that quite looks like that. Is it a characteristic of Solanum habrochaites?

[goodwin]

hi redbaron -
I have started LA1777, a high altitude accession of Solanum habrochaites (or Lycopersicon hirsutum) to use and it sets clusters of flowers. The species is indeterminant.
The photo is of an excellent cold-tolerant variety of cherry tomato I was thinking of trying in a cross. Koralik also has a very high sugar content. Another variety to use might be Nepal which will set and ripen under very cool conditions.
Crosses made to wild species should show an improvement in cold tolerance, and I plan to include tomato varieties which already demonstrate some resistance.
Wild species like LA1777 close their stomata during chilling, preventing wilting. But their root systems also will grow in cold soils, so it might be interesting to attempt grafting as well.
Here is a link to some research on this topic.
www.tuinbouw.nl/files/page/Bijlage%203_10450-04_1.pdf

I need to wrap up this semester, and then I'll be working on this and some other projects.
Lee

[Fusion_power]

Goodwin, you might also want to take a look at LA4135.

DarJones

[Heritage]

Darrel,

A great, ambitious project! I'm particularly interested in your approach toward developing the flavor (especially sweet) and texture (not mealy) in tomatoes ripened under cool/cold temperature. My winter greenhouse (unheated) has night temps averaging 40-45 F. I have no problem getting good fruit set on most OP varieties, but have yet eaten a winter vine-ripened tomato with flavor and texture noticeably better than supermarket standards.

Good luck!
Steve

[doublehelix]

Before I planted dozens of TGRC accessions, I would want to know if what happened was just an anomaly. Almost every year I have grown plants there has been something survive a frost and even a few hard freezes. There could be a number of things that caused a small area of protection from freezing in a field or garden. If you want to do serious research, then you need to ask the fundamental question of "what went wrong" and not assume something is unique.

Until you take the variety that survived your freeze and subject several plants to freezing conditions in a controlled environment you won't know if they can consistently survive a freeze. You would need a substantial number of plants and a place where you can accurately control the temperature. You would also need a second variety to use as a control group. You would also need to hold the plants at a set temperature and vary the exposure time. You would also need to conduct this experiment on different age plants.

A research plan might look something like this:

6 week seedlings Group A test plants

32 degrees 1 hour
32 degrees 2 hours
32 degrees 4 hours
32 degrees 8 hours

30 degrees 1 hour
30 degrees 2 hours
30 degrees 4 hours
30 degrees 8 hours

28 degrees 1 hour
28 degrees 2 hours
28 degrees 4 hours
28 degrees 8 hours

6 week seedlings Group B Control plants

32 degrees 1 hour
32 degrees 2 hours
32 degrees 4 hours
32 degrees 8 hours

30 degrees 1 hour
30 degrees 2 hours
30 degrees 4 hours
30 degrees 8 hours

28 degrees 1 hour
28 degrees 2 hours
28 degrees 4 hours
28 degrees 8 hours

If everything dies at 32 degrees you don't have to continue to the next phase of the experiment. There isn't any point in breeding until you have this information.

[doublehelix]

I hate to be the one that throws the wet blanket on this project but since no one else has pointed out the improbability of it, I thought I would.

It's always important to do the math when dealing with genetics. If we assume that only 10 recessive genes are needed to give you the 10 traits you desire (post number 50), then you will need to grow out 1,048,576 tomato plants to find one with all of those traits. Chances are, there are actually more than 10 genes involved and this number does not take any kind of linkage into consideration. Assuming it would take about 5 minutes to plant each tomato it would require 87,381.3 hours to plant them. Given a one week window of field planting, and a 40 hour work week, that would mean you would need a work force of 2,185. It would require an even larger amount of time and work force in order to pick, document, and evaluate each plant. I don't even want to think about how much greenhouse space and the cost of potting mix and containers it would require to start 1,048,576 tomato seedlings.

Then when you start throwing in other traits(genes) that have been included in subsequent posts like crack resistance, fruit size, and keeping qualities, you now have increased your grow-out number to 67,108,864.

That is over 5 1/2 million man-hours just to plant them.

None of this even takes into account any plant physiology or biochemistry.

Many biochemical pathways will not function at those temperatures and there are a slew of enzymes that cannot be made below a certain temperature.

First, see if your plants really can survive a freeze. Then try to breed for that quality and that quality alone.

[Fusion_power]

Doublehelix, this is not a parade, and I don't mind some rain. After all, I am a gardener.

I've already taken into account each of the factors that you have listed. The number of plants required is off by orders of magnitude. The intent is NOT to try to grow one single plant with all the desired traits, but rather to assemble the desired traits one step at a time. I know already that NONE of the available genetics in S. Lycopersicum is capable of the low temperature tolerance that I am searching for. There are two places where I can get that tolerance. The first is from S. Habrochaites which lives at altitudes up to 3100 meters and the second is from S. Lycopersicoides which lives up to 3600 meters (2 miles). Both have noted cold tolerance but only S. Habrochaites has been studied enough to say which lines are likely to give desirable results. LA3969 from TGRC is noted to be particularly cold tolerant. I also have LA1777 which is the pure S. Habrochaites parent of the introgression lines.

I have seed either on hand or ordered or requested for about 20 tomato varieties that have been selected over the years for cold tolerance. My intent is to start with these varieties and compare them with the best of the wild species. Then I will introgress traits from the wild species into selected tomato lines. How long will it take? Well, I am conservatively projecting between 10 and 25 years. It is NOT a short term project. The gene stacking will require access to technology I do not currently have. What I do have already on hand is the means to begin testing plants for cold tolerance.

Cold tolerance is composed of numerous traits of which the ability to survive an overnight freeze is just one small component. The ability of a plant to grow and thrive at low temperatures is even more important. The primary limit on growth at low temps is associated with photosynthate transport from the leaves which becomes very inefficient at 60 degrees and pretty much shuts down at 45 degrees. Tomato plants can take lower temps, but they do not grow. My initial efforts will be directed toward finding tomatoes that can grow at temps between 32°F and 50°F. All I need to find such plants is an ordinary refrigerator, a bunch of cell trays, and some seed.

You are right to be pessimistic. Even tomato programs with years of work behind them are not optimistic about developing cold tolerant tomatoes. But I have looked at the available wild species and I can see where the tolerance can be found. It can be done.

DarJones

[goodwin]

The technology is becoming more available. A java program like Artemis will read genetic databases. You can imagine the possibilities if we had inexpensive sequencing. There's a project for your spare time!
Lee

[Fusion_power]

Google translate has some serious limitations. I was searching for "Павла Сараева томато" (Paul Sarajevo tomato) and then reviewing the translated pages. This one gave me a laugh with the line "Stepchildren are not circumcised." I think from context it means that sideshoots are not removed.

http://translate.google.com/translat...ed=0CD4Q7gEwAQ

DarJones

[Redbaron]

Originally Posted by Fusion_power

Google translate has some serious limitations. I was searching for "Павла Сараева томато" (Paul Sarajevo tomato) and then reviewing the translated pages. This one gave me a laugh with the line "Stepchildren are not circumcised." I think from context it means that sideshoots are not removed.

DarJones

Well Dar,
One things for sure. That guy is lazy! A man after my own gardening heart. Maybe a contest to see which of us is more lazy?

Of course to be fair. No one who gardens is completely lazy. Otherwise they would just buy at the grocery store. Except me. I am so lazy I can't be bothered to start the car and drive all that way. Easier to pick a tomato in my back yard!

[Fusion_power]

I am working on defining the basic concepts and issues with developing a cold tolerant tomato. These are some more thoughts along lines I've already looked at and adding some new items. The first and most important statement is that there are a bit over 500 genes involved in the stress response biopaths for S. Lycopersicum tomato. At least 1/3 of them are not activated by cold temperatures. By comparison, S. Habrochaites activates nearly 200 unique genes when exposed to cold. The number of genes involved indicates that multiple external traits are invilved.

One item I needed to define is exactly what temps a tomato can stand.

120°F = Severe heat, but if plenty of water is available, the plants are fine. This temp is way above levels at which pollination can take place. Plants with heavy fruit set may show stress.

92°F = This is the temp at which pollen starts clumping and blossoms begin to drop.

70°F to 92°F = This is the goldilocks zone. Tomatoes grow prolifically, flowers set readily, plants need maximum fertility in the soil. The high end of this range is optimum for spread of several foliage diseases.

65°F to 72°F = the best temperature to grow seedlings.

50°F to 65°F = this is the beginning of cold stress. Tomato plants in this range grow slowly, often produce anthcyanins (turn purple), and become pale green from loss of chlorophyll function.

32°F to 50°F = This is the range where normal tomato plants show severe cold stress. Leaves shrivel, turn yellow, wilt, stems lose turgor, roots stop absorbing water.

28°F to 32°F = This is the maximum range most tomatoes can withstand without freezing. Note that if frost forms on the leaves, then the leaves will freeze and die. The plant may live and can form new leaves, but the stunting effects take quite a bit of time to overcome.

22°F to 28°F = This is the range that a few select varieties can withstand for brief periods of time but stipulating that frost on the leaves will still kill them.

15°F to 22°F = This is the range that a few Russian cultivars are reported to survive, again only if frost does not form. The reports I have read indicate that this tolerance is only for a limited time period, in other words, repeated low temps for 3 days or more will still kill the plants.

0°F to 15°F = A few Russian cultivars are able to handle temps this low for brief periods of time. This is the low end of the range that wild tomato species S. Habrochaites, S. Chilense, and S. Lycopersicoides can withstand.

As the temperature goes below 60°F, tomato plants enter a state where normal photosynthesis ceases. Sugar accumulates in the leaves, rubisco - a crucial chemical in the plant- begins to be deactivated by free radicles. This process causes the leaves to become dysfunctional in such a way that they can not recover. One very special trick that greenhouse growers MUST know is that if plants are exposed to overnight lows below 45°F then the greenhouse must be let rise to a high temp near 100°F the next day. If this is done, then the plants totally reverse all effects of being too cold the night before.

Here are a few of the breeding objectives.

Able to tolerate extremely low temps for short periods of time
There are several components to this high order trait. The leaves must be able to close stomata to avoid dessication. The leaves must be thicker than normal again to avoid desiccation. The stem must be able to maintain elasticity and conduit ability for photosynthate from the leaves and nutrients from the roots. The roots must be able to maintain absorption of nutrients.

Fruit must be able to tolerate freezing temps
The fruit must not freeze damage as a result of cold where typical damage is gray soft areas inside the fruit skin. The fruit must maintain expansion even when cold temps limit biological processes. The plant must be capable of translocating nutrients from the leaves and roots to the fruits.

Flavor must be maintained regardless of temperature, especially at fruit maturity
This requires that the leaves must be able to produce the volatiles that compose aroma and the terpenes associated with flavor. There is an implied problem with calcium channel signalling at low temperatures. Selection must be maintained for fruit that are healthy and well developed.

Pollination must be able to occur at temps from 32 to 50 degrees F
There are several issues with pollination since most tomato plants do not set fruit at temps below 50F. The first is precocious flowering which would seem to be a required trait. Another is for pollen production which is necessary for fruit enlargement to occur. I have LA2006 with the ft gene for flowering at low temps, but that does not necessarily include production of pollen. S. Habrochaites produces pollen in the desired temp range so it may be the best source of these genes. I do not want to use the parthenocarpic genes because they infer several physiological processes are dysfunctional.

Able to grow at low temps where most tomatoes shrivel up and shiver (range 32 to 50 degrees F)
This is currently a non-existent high order trait in S. Lycopersicum. I am not certain if any of the cold tolerant cultivated varieties I have accumulated so far will help any in this regard. I have researched enough to know that this ability is in S. Habrochaites and in S. Lycopersicoides. I plan on relying heavily on these species to bring in the required traits.

Able to grow and produce in a cool climate, i.e. with less growing degree days for the season
This is a significant new direction for the breeding work. Areas such as large parts of Oregon and Washington have normal summer temps that are almost too cool for tomatoes to grow. The physiological adaptations required for growing at 32 to 50 degrees F should also help with growth in areas that have low average temps. The objective then should be to reduce the number of growing degree days for tomatoes to produce a crop.

Here are varieties I have accumulated so far and reasons for including them in a cold tolerance breeding program.

Bellstar - Jointless and was developed in Canada with a degree of cold tolerance
Wheatley's Frost Resistant - has cold tolerance, but seems oriented toward late season rather than early spring
Glacier - Small early and productive with some cold tolerance
Stupice - Small early and productive with some cold tolerance
Siberian - Small early and productive with some cold tolerance
Tastiheart - my selection that survived 22 degrees F April 7th 2007
LA2006 - ft gene for setting fruit at low temps.

Crosses I plan on making 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 C line. Hopefully will be able to increase vitamin C significantly.
Nepal X ? - To bring in good flavor genes
KBX X Bellstar - to get the jointless gene into a good flavored large fruited orange.
Tastiheart X PI 126256
Atkinson X LA3969 - to move the chromosome 12 segment into an adapted southern variety

I'll add more crosses as I think of them.

DarJones

[Tania]

Darrel,

This is a fascinating project and a huge undertaking! I have been enjoying reading your notes. Thank you so much for sharing your thoughts on the subject. And good luck!

Tatiana