Frost and Cold Tolerant Tomato Breeding including epigenetic and regular genetic

[William S.]

One of the nonsensical things that happened in 2017 was a Blue Gold survived a frost with top growth when all the plants of the same variety around it froze to the ground and resprouted. Seed saved for a few generations of consistently harsh springs and I bet epigenetics is triggered. I suspect that is the case with some of the cold hardy varieties. Wouldn't be surprised if plants that resprouted from the ground have epigenetic change too.

Something I think would be kind of cool, especially with an abundance of home saved seed, would be to have something like 90% mortality. In my garden so far no matter my scheme intentional or unintentional: freezing, dry farming, direct seeding, that is a very rare level of mortality. Might have come closest in 2017 with plants exposed to two spring frosts- the earliest I transplanted. I am spending a lot of time and effort trying to get some exotic DNA from wild tomatoes, but perfectly ordinary tomatoes as long as reasonably short season, seem to do perfectly well with everything I have come up with to thwart them except for multiple frosts and my very worst shallow clay soil.

One very ordinary tomato I think would be good for anyone looking to start a grex with would be Sungold F1. It is short enough season to direct seed here. It and its descendants taste good. There is sometimes some exsertion of stigmas so outbreeding is possible. Its an F1 so some variability is already built in. 

With the wild x domestic hybrids I have had 90% non-reproduction before. Though the plants survive they just don't set fruit. That may be the case again this year as its an F2 and the two breeding systems seem to have complex incompatibilities. In 2018 I think I had one of a dozen F2 hab crosses produce a fruit and one of a dozen F2 penellii crosses produce a fruit. I planted more plants in 2019, still had a lot of infertility in the penellii. My solution to that for 2020 will be to plant much larger numbers of seedlings this time. That was basically just selecting for fertility though.

[Dominic J]

Quickly looked through my seed box, and look at that: [Mountain Magic 2017 (frost resistant?)]

If I'm looking at my archives right, a first light frost occurred on the 12th of October 2017, and a killing frost occurred by the 25th, and by then only 1 plant still looked alive and it was one of the Mountain Magic plants (the other Mountain Magics, Defiants, and Plum Regals had perished).

Got a bunch of seeds, 100 or so probably. Guess I'll be sowing that this year.

[Lauren]

Wow. I tried Startpage and excluded -razor -nose -beard -philips, and still got five pages of nothing. Maybe nobody is breeding it? But I should think there would at least be a mention of the variety.

[William S.]

Or Tom never released it to the general public.

http://tatermater.proboards.com/thread/416/resistance-cold

Here is the link (above) where Tom said it.

I still have saved seed from 2017's lucky/potentially epigenetically changed plants like a mixed envelope of blue gold from both plants that resprouted and the one that didn't need to resprout. I have less need to grow Blue Gold now that I have my own shorter season blue skinned bicolor started so probably won't plant it again this year.

I wonder what it takes to trigger those epigenetic changes and keep them triggered. Is it enough to live in a colder climate and save and start your own seed? Does direct seeding help? Do varieties that consistently volunteer year after year get the local epigenetic changes locked in? Or does it only happen in particular climates or in particular years?

[William S.]

Over on tomatoville Lee Goodwin of J and L gardens posted this on the http://www.tomatoville.com/showthread.php?t=25599&page=9 interesting breeding possibility thread Darrel started.
"I'm continuing with this project, now working toward tomatoes grown in unheated hoophouses for the early market. At this point I have several S. habrochaites crosses with good cold-tolerance (down to 25-28 F several nights in a row). Two also have excellent fruit set and flavor. They are both large cherries, shown below. I plan to slowly increase the size by crossing back to Sasha's Altai or others like LA3969, 0-33, and I-3.
I also requested some seedstock from GRIN which should arrive shortly. It includes high brix lines, two more accessions with the (sucr) trait, and a few ultra-early strains like Beaverlodge 6714."

That strongly suggests that breeding with LA 1777 has some possibilities for this. I have purchased packets of Lee's new Wild Child and Weight in Gold varieties to try in 2020. Very cool work I am intrigued. Though will probably only grow one plant or clump of plants to try them.

Lots of LA1777 in the background of the promiscuous tomato project. Will be interesting to see what crops up there in the way of cold and frost tolerances. Also they've been grown for generations in Josephs and now my conditions. So should be well on the road to adaptation.

[Dominic J]

It's possible he misspelled or misremember the name, and that Norelco is not the right name.

As for epigenetic, could be a lot of things. Exposure to freezing temperatures while a seed. Exposure to freezing temperatures while a seedling. Constant exposure to freezing temperatures. All of these, but with cold instead of freeze?

There will probably be some physiological barriers that are harder to overcome than others. In most trees and shrubs, flowers and floral buds are the least hardy part of the plant. Getting a plant to resist freezing might still not mean that its flowers/fruits will survive under 40F. "Cold resistance" molecules might not distribute evenly within the plant.

How does the supposed frost/cold tolerance work, anyways? Some species will fight cold by generating heat (i.e. skunk cabbage).  Some species will fight nucleation of ice crystals by modifying their internal solutions so as to lower the freezing point (ex. increased sugar content in quinoa, supercooling). I suspect some resist by modying their susceptibility to cell burstage due to freezing. Glycerol can be added to a yeast solution to prevent crystal formation (is this another example of supercooling?). I can't give examples, but it's possible that some species may be able to insulate themselves, to offer minor protection from cold/frost (though given how thin plants are, this effect is probably going to be extremely minor at best).

It's known that brassicas respond to frost by sending sugars into their leaves. I'm no expert on the subject, but I'm getting the impression that storing sugar into leaves is the main form of frost tolerance in plant species. By extension, testing tomatoes for higher sugar content in their leaves would possibly work as a proxy for frost resistance, and measuring sugar content following various treatments (seed exposure to frost/cold, seedling exposure to frost/cold, plant exposure to frost/cold, non-exposure to frost/cold) would probably be able to give hints on the underlying mechanisms.

[William S.]

Tom replied on his forum. Called it notelco this time, but says he isn't releasing it.

https://www.nytimes.com/1977/05/14/archives/upstate-scientists-is-trying-to-breed-a-tomato-that-can-stand-the.html

This article from 1977 is something I found awhile back But had lost. It's an interesting bit of history on cold/frost tolerance breeding.

[Nicollas]

That strongly suggests that breeding with LA 1777 has some possibilities for this. I have purchased packets of Lee's new Wild Child and Weight in Gold varieties to try in 2020. Very cool work I am intrigued. Though will probably only grow one plant or clump of plants to try them.

Interesting, i wonder the fruit size of "Weight in Gold". The description says nothing about it. Any clue ?

[reed]

I don't worry much about frost tolerance in tomatoes cause my season is plenty long, I don't need to. But I do have a lot of volunteer tomatoes both in late summer and early spring and I see definite differences in them as far as tolerance goes. A later frost may kill most but not all of early volunteers and similar thing in the fall. Of course the fall volunteers all end up frozen eventually but some last considerably longer than others.

I often keep some of the spring volunteers, wonder if I accidentally selected for tolerance. I never tried or looked for varieties with cold tolerance mine are all pretty generic by plant breeding standards. I reckon cold tolerance if there is any would about have to be epigenetic.

[William S.]

Interesting, i wonder the fruit size of "Weight in Gold". The description says nothing about it. Any clue ?

Yeah, small is my guess from what Lee said about them on tomatoville.

[Dominic J]

I worry more about late Spring frost than early Fall frost, personally. Gardeners around here like planting their stuff much earlier than they should, and even if one waits, frosts or near-frosts do occur in early June. I don't mind waiting 'till the first of June, personally, but waiting for the 8th is a bit too much.

[William S.]

I worry more about late Spring frost than early Fall frost, personally. Gardeners around here like planting their stuff much earlier than they should, and even if one waits, frosts or near-frosts do occur in early June. I don't mind waiting 'till the first of June, personally, but waiting for the 8th is a bit too much.

2017 was a fairly early spring here but I got a little overconfident about long term 15 day weather reports and planted early. Thus everything got frosted and some things got frosted twice. Also direct seeded seeds germinated early enough to get frosted a little

2018 I waited till closer to average last frost here of May 15th and no frosts.

2019 was a very late spring but I still set everything out around May 15th and there were no more frosts. Volunteers responded to the cool weather and came very late- after all danger of frost was past. Peruvianum did not volunteer until it was too late to set fruit. I think it needs a decent rainfall event or something to prompt germination.

It is possible to catch a late frost here even into June. Though I also know now from 2017 that many tomato plants will resprout- though it may be worthwhile to bury them a bit deeper when out planting.

So to flirt with spring frost I really need to set things out early- maybe even late April. Not really planning on doing that this year.

2020 valley floor winter precip is low especially in the form of snow- I expect no vernal pool this year, unless we get drastic snowfall again in March. Could be heading towards a warm or at least dry spring.

So if you are out planting June 1st and should be June 8th. Then frost tolerance might be plenty useful for you!

Though there has been talk on the other forums- it perhaps only works with dry frosts without dew.

[Dominic J]

Dew is said to help plants resist frost, though, isn't it? That's why strawberry growers will occasionally irrigate their fields in the case of frost, to help protect the plants.

http://www.omafra.gov.on.ca/english/crops/facts/frosprot_straw.htm

When do you typically sow your tomatoes, and what caliber plants do you typically plant outside in the field?

People around here seem to like to plant their stuff around the 21rst of May, which in my opinion is too early. It is pretty frequent that it freezes at least once after the 21rst, or that near-freezes on bought nursery plants will otherwise pretty much damage them beyond repair. The only June frost I remember was in 2015, and not every region actually froze, some only dipped to 2-4C or so, and that was around the 6th of June if I remember correctly.

I think I'll be trying some chill tests on my seedlings from my 2017 late frost Mountain Magic survivor. I've got a few small fridges that aren't serving any purpose, I'll just stuff the seedlings in there. Not sure how cold I can make them go, but I can also stuff them in my spare freezer. Though unless I buy myself an inkbird, even at the warmest setting, the freezer is probably going to be too cold. There's always the option of just stuffing them outside when the temps are around -1C though. Cheaper and simpler.

[William S.]

"When do you typically sow your tomatoes, and what caliber plants do you typically plant outside in the field?"

It has been changing. I'm in school again for a teaching certificate and spring break is about 6 to 8 weeks before may 15th which is the expected date of last frost. So transplants usually get started at spring break. Plants are whatever size they get to by may 15th and if the weather reports are good I pop them in the ground and walk away.

Direct seeding I think it would be fine to plan for germination to start as early as ten days before last frost. So plant 20 days before expected last frost. This is when I would plant if I wanted the direct seeded seedlings to have a chance of flirting with frost.

In 2017 the first year I tried it I planted one small dense block direct seeded in March. Most of them were an inch high for the last frost and most of those survived. A few varieties seemed more susceptible. Being close to the ground may have some advantages.

In 2018 and 2019 nothing came up or volunteered till after last frost.

May 15th is also fine for direct seeding here. I would not expect these seedlings to have a high chance of flirting with any frosts. Though it's possible, just rarer.

Tomato seeds seem to have a fairly decent self regulation system when it comes to germination. I had some really decent big 1" rainfall events in 17 and 18 with good timing. I think that is why the peruvianum didn't germinate at the proper time in 2019. There wasn't a large enough rainfall event at the proper time. Temperature wise they seem to wait for reasonably warm temperatures. Some years like 17 fake that out a little. Other years like 19 it doesn't get warm enough to germinate till after all risk of frost.