Breeding with wild tomato species

[Joseph Lofthouse]

(BH X W - XL 2019) is one plant selected out of BH X W4.  It was pollinated by smaller fruited varieties, which carry recessive genes for beefsteak sized fruits.

[Andrew Barney]

Looking good! Looks like I should grow out as many wild tomatoes as I can this year to do my part!

[William S.]

(BH X W - XL 2019) is one plant selected out of BH X W4.  It was pollinated by smaller fruited varieties, which carry recessive genes for beefsteak sized fruits.

That's about the downside of the obligate outcrossing. No or very low selfing rates make for a different game. Though maybe we will be able to clone some of the best plants and mass cross them over the winter....

Then the offspring of those might be great pollen donors for back crossing to obligate outcrossing mothers. Like the new habrochaites line I hope to bring into the population.

[Joseph Lofthouse]

I cloned (BH X W - XL 2019) and have managed to keep it alive until now. Though wasn't able to make any crosses with it because the proposed parents didn't flower at the same time. It has remained fruitless due to self-incompatibility. I really like the idea of cloning to produce manually pollinated crosses during the winter.

Andrew: What's your growing space looking like for this summer?

[Andrew Barney]

I'm planning to put in some raised beds here at the rental property this weekend so I can have some space here at the house. My planting space is small, but perhaps sufficient. I just need to plan and try to balance what I really want to grow and what things should take priority.

Another great benefit to collaborators with things like the watermelon project. Means others might be able to do better work than me on it this year.

I do still have space at my parents property to grow things,  but I don't know how much I will do that as it takes time traveling and maintaining two gardens with limited time especially when balancing work schedules. I'm not sure how one could do it with multiple properties and a regular job.

Joseph, how well do you feel this tomato project is progressing? What still needs to be accomplished? And what traits or lines are most exciting for you? What is your ideal tomato that has the potential to be bred from this project? How did the mango tasting tomatoes fare last year?

[Joseph Lofthouse]

Andrew:

Yup, long-distance gardening can be difficult.

I just finished an article for World Tomato Society about the history of the Beautifully Promiscuous and Tasty Tomato Project. Wow! What a sweeping complicated project!!!!!

I feel really good about the state of the project.

I distributed small-ish amounts of seed to about 50 growers, who are largely unvetted, though some have collaborated well with me in the past.

I distributed large amounts of seed to 5 growers, that I have collaborated closely with in the past. I know and trust them to follow through. They are growing about 100 to 200 plants each.

I still have some seed for sharing. The best of the best has already been distributed. There are some scientifically or artistically interesting lines that could still use collaborators. For example: I'd love to have more growers in areas that can't grow tomatoes organically because of blight.

The project is entering a stabilization phase. I'm not introducing any new domestic or wild ancestors into the general population, and am growing the promiscuous tomatoes in isolation. I expect this year that we will focus heavily on selection for taste, earliness, and productivity. (And as always: Self-incompatibility).

With so many collaborators, we're able to explore sub-projects that wouldn't otherwise be possible: For example creating a population where the self-incompatibility system is fully functional, and creating a population of only 3 species hybrids, and separating the population into sub-populations based on traits like fruit color, taste, and fruit size.

My role has changed from grower to project manager.

[William S.]

Joseph you said you are isolating the general population of the project from new wilds. I'm going to be growing penellii (in hopes of pollinating peruvianum) and a new accession of insect resistant habrochaites this year. Should I isolate them from the main project? Maybe put one plant of say H X ((BH X Wh) or (BH X Wp)) in with the new habrochaites in hopes of starting the process of integrating those genes? But keep it in an isolation block for a few years? Maybe carry over some other pollen and dust it on stigmas?

Of the four accessions you distributed this year do you consider them all general population or are some like
H X ((BH X Wh) or (BH X Wp)) still not up to that par?

It strikes me that it would be cool to use clones as pollen donors to bring new wild accessions up to par faster.

[Joseph Lofthouse]

William, I expect that if you plant S pennellii anywhere near the interspecies hybrids, that it will be pollinated by them. I'd place more value on S pennellii X S peruvianum crosses. For me, it's really hard to grow a single plant of S pennellii. They are so far out of their comfort zone in my ecosystem. Growing in pots might work for me, then put them together for crossing.

This summer, in my garden, I'm working on stabilizing for great taste, and yellow or bicolor fruits. Therefore, I'm keeping the mostly wilds away, because their offspring are usually green fruited in the F1. I have arranged locally for 6 small plots where I can grow out the wilds and mostly wilds in isolation. In a few years, I expect to incorporate some of those into the main project.

Maybe put one plant of say H X ((BH X Wh) or (BH X Wp)) in with the new habrochaites in hopes of starting the process of integrating those genes? But keep it in an isolation block for a few years? Maybe carry over some other pollen and dust it on stigmas?

That sounds awesome to me. Eventually, I want a population that is 75% or more S habrochaites, with a few domestic traits like larger fruits.

H X ((BH X Wh) or (BH X Wp)) is not elite general population. It is mostly wild. Fruits this year are expected to be green and sour.

The reciprocal cross (BH X Wp) X (H or (BH X Wh)) is also not elite general population. Many of the fruits are likely to be green and sour.

[Joseph Lofthouse]

I got an email a minute ago from a grower who is making hybrid crosses for us this winter in a warmer climate. The elite population is looking fabulous! Much better than I had hoped for.

[Diane Whitehead]

I've just ordered a packet of your S peruvianum seed from the Experimental Farm Network.

You don't seem to have used it much for your promiscuous plants.  Is there a reason?

[William S.]

I've just ordered a packet of your S peruvianum seed from the Experimental Farm Network.

You don't seem to have used it much for your promiscuous plants.  Is there a reason?

Yes, I've been growing the Peruvianum population from Joseph for three years now. It is a difficult cross to make. It's possible there are specific accessions of Arcanum and chilense that may bridge. It may accept penellii pollen. And the third possibility is embryo rescue of the cross with domestic tomato with the Peruvianum as the pollen source.

I'm working on the bridging possibilities because they seem more toddler parent friendly than me actually having the opportunity to make the 100 or so crosses and have one big tissue culture binge x days after pollination to make it work...
I do have a protocol and a paper or two I could forward to anyone with time and plant tissue culture skills who wants to have a go. I got a couple crosses but only indoors. Then work caused me to miss the window. The fully mature seed did not germinate which is what the papers said would happen. I got maybe 5 seeds that looked worth cutting open if I could have done it on the proper day.

The chilense accession didn't make it to adulthood for me last year, I have more seed to try again. .

Arcanum accessions both did great. Probably will recover arcanum x Peruvianum hybrids this year. In theory 0.2 hybrid seeds with domestic should be viable per pollinated flower so one seed per 5 pollinated flowers. So 100 pollinations for 20 viable seeds. Possible a few could show up in seedling trays this year, but would be better if I could emasculate and pollinate 100 flowers this year. Also possible those twenty seeds would still need embryo rescue in addition...

This year I plan to plant a little block of just penellii and one peruvianum to see if the peruvianum takes the penellii pollen.

Joseph has also started selecting for improved peruvianum within species.

Oh also I think I have a whole thread for this somewhere around here http://opensourceplantbreeding.org/forum/index.php?topic=7.0

[Andrew Barney]

I think I have seed for Joseph's improved peruvianum. I still think it might bridge with pennellii with effort. I'm thinking penellii or a pennellii hybrid as the seed parent and puruvianum as the pollen parent. I may try the -5 day flower method with walnut oil again as immature flowers have no or partial breakdown of incompatibility mechanisms.

[Andrew Barney]

Dang it! Now I'm hooked on this project again! Guess I will be making sure plenty of my garden plans this year are spent on wild tomato breeding! You two are terrible influences!

I'm kinda wanting to grow out the fairy hollow line looking for non hollow fruits. I feel like there is missed opportunity in that line somewhere.

P.s. great article Joseph! I found it on your Facebook page despite no longer using Facebook. I look forward to reading more articles by you on this topic.

[William S.]

https://www.frontiersin.org/articles/10.3389/fpls.2019.01606/full

Was just looking at this article. It's about how introgressions from peruvianum, chilense, habrochaites, and pennellii have helped with the diversity problem in tomato.

Some of the introgressions are quite large according to the article. A common one from Peruvianum is ToMV resistance to tobacco mosaic virus which comprises about 70% of chromosome 9. So when we cross in modern disease resistant varieties we get some decent wild chunks. Perhaps things like the variety Iron Lady F1, that Carol mentioned in her call to action book section on late blight, actually have some decent chunks of wild including peruvianum. Perhaps more than older varieties like the Payette I mentioned. Intriguing if so. If I were starting over with new domestic lines that might be informative. No plans at current though.

Though this would be my scheme if so. I would look for modern hybrid varieties with the largest lists of resistances possible because each of these probably corresponds to an introgression chunk. Then I would pollinate those with about ten+ elites from the promiscuous project. In the promiscuous F2 there would probably be some reproductive difficulties, but then you would probably end up with a promiscuous line with a lot of disease resistances and a lot of corresponding introgressions from all commonly used species.

Joseph in some of his older articles about his first attempts at tomato land races mentioned the genetic value of modern varieties. This article would seem to support that strongly.

I suspect also that this article means that almost any modern variety probably has more introgressions in comparison to heirlooms than we might think. Like all the blue skinned have the blue introgressions. That's a lot of varieties and super common in my garden. So since we haven't been extremely focused on working with older heirlooms only the domestic plants we started with probably already came with some introgressions.

[William S.]

Planted tomatoes this morning.

BH x W4 F2 (my 2019 garden) I have so much of this seed I think I am going to have to direct seed most of it. I went a little gung ho on a tray and seeded ~150 seeds in it. That was the smallest envelope, but also probably the earliest.

7 seeds of larger odd striped hab x domestic F3 (my only ~ elite in 2019 and the only descendent of 2018 hab x domestic that I grew worth planting in a pot). Honestly the seven seeds looked a little eh, so will see if they germinate.

BH x W Best Tasting (Joseph's 2019 garden)

BH x W XL (Joseph's 2019 garden)

Big Hill (last ten seeds in original packet from Joseph)(domestic)

Exserted Orange Hill F3 (domestic)

Exserted Tiger F3 (domestic)

Payette (Domestic)

That filled five trays of the eight that fit under the lights (360 cells). I have three more empty trays for the wilder wilds (176 cells) but haven't got them seeded yet. Nice day so going to take advantage of the young sir's naptime to go out to the land now to shovel sand around to improve my once and future tomato patch. Tilth is pretty good as its been very dry so I should perhaps rototill more, but will probably stick with the shoveling for a bit yet as the weather is supposed to hold and I got four truckloads of sand for the big patch. While I am out there I need to search out an envelope of Peruvianum seed for planting with Penellii as all I seem to have on hand is Arcanum. I suspect all my 2019 Peruvianum went into a 2019 wild mix for direct seeding that I might not get around to direct seeding this year with some space issues that have developed with the need to keep things separate.

Also may want to direct seed the envelopes of domestic exserted that I daubed with wild pollen. Could be some interesting hybrids in there. If not I may plant them in community flat trays in the hopes of pricking out hybrids and or both direct seeding and community flats. Have big envelopes from Big Hill that was close to Penellii and Habrochaites hybrids and Blue Ambrosia with good exsertion ditto- and I daubed the pollen on the stigmas. Could be some interesting hybrids therein.