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Old December 26, 2012   #70
Fusion_power's Avatar
Join Date: Feb 2006
Location: Alabama
Posts: 2,068

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.

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