Crossing with Solanum Habrochaites

[nicotomato]

Great project !

How did you habrochaites plant in the disastrous 2021 season ? Any resistance to late blight ?

I'm planning to do some crosses with habrochaites LA1777 this year.

From what i'm understanding, late blight resistance should come from at least 4-5 QTL so not very easy to get into a good fruited line unless growing a lot of plants

[Frosti]

The primary goal of this line is to find and stabilize a dwarf with the beautiful and virtually disease free leaves of S. Habrochaites.

But they stink!

no they don't??
I've had S. Habrochaites plants for more than 2 years now and I never noticed a different odor than ordinary tomatoes. I've just double checked with 30 of my S. Habrochaites F2 seedlings crammed into a space of 2.4 x 5.5 square inches ... Remember there are multiple sub variants of S. Habrochaites, maybe I simply got lucky. Ooor my sense of smell sucks, hayfever be damned!

[Mark_Thompson]

Oh interesting. I’ve only grown one and the smell is super strong. Very different from domestic tomato. Even when I just water it I can smell the plant. Guess the joke isn’t funny when yours don’t smell

[Frosti]

Great project !

How did you habrochaites plant in the disastrous 2021 season ? Any resistance to late blight ?

I'm planning to do some crosses with habrochaites LA1777 this year.

From what i'm understanding, late blight resistance should come from at least 4-5 QTL so not very easy to get into a good fruited line unless growing a lot of plants

Unfortunately I did not document the 2021 season very well. It was an unusually wet and cold season in my area. I don't remember it dying to late blight, though.

I do have records of last year's season though. The F1 didn't have a hint of late blight on it at the end of October, while others were more brown than green.
Here's the plant on the last day of tomato season (Oct. 22nd)

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For reference, the broken meter stick is about 155cm long.

[Frosti]

Noticed something interesting today with one of my plants. This plant seems to always grow two branches at the same time and it seems like this plant is obsessed with being the most symmetric tomato plant ever. Look at the new growth, is it splitting already?! This one is special, I'll keep an eye on it.

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[nicotomato]

The architecture and foliage are very pretty !

[Frosti]

This is the symmetric plant a few weeks later:

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It's still growing symmetrically!
By the way, it's been named 40-23.
Overall I've got 22 to 24 plants from the Habrochaites cross that I'm following up on.

[Frosti]

Okay, so a few more weeks have passed and I can now report some observations. There are two plants per 16L bucket.

a) I selected for dwarfism and culled the rest, but these plants do not seem very dwarf-like at all. Since I do not expect these plants to bear very good tasting fruits they have been put into the worst locations. These locations are not sheltered from rain and receive less light than the other locations. Maybe that is the reason why these plants are so gigantic for dwarfs? One can clearly see the rugous foliage on some of them, which is commonly associated with dwarfs. Some other dwarfs lines are at the same location and they are also bigger than expected.

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b) Most of the plants have pollination issues, some don't even form fully mature flowers. So fruit set is very low. I suspect this could have something to do with the low light conditions, but the other dwarf lines nearby have no such issues and set fruits just fine. Maybe S. Habrochaites and its offspring are more demanding regarding the light intensity? It's also noteworthy that the fruits that do set, look a hell of a lot like S. Habrochaites fruits.

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c) The symmetric plant is not growing symmetrically anymore. Unfortunately it is one of the plants that seems to be unable to even flower. The latest attempt seems to be going better than the preceding though.

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This one is at a different location (also with low light intensity) and is not as large as its siblings. It also isn't competing for resources so much, since it has a pot of its own.

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[bower]

@Frosti we had a very dark early season here with hardly any sunshine through June, and my determinate plants are enormous. They are all as big as indeterminates would be. So less light can definitely change the growth habit.
WRT not setting - is habrochaites one of the non-selfing type tomato relatives? If so, your plants may have inherited that characteristic, and require some pollinators to visit flowers in the group of plants...
The lovely symmetrical plant might want to be hand pollinated by you.
I have followed a few discussions about non-selfing tomato projects but not too closely, however I think flower structure plays a part in the non-selfing, rather than any genetic barrier to selfing. So you should be able to pollinate the symmetrical plant with its own pollen from another flower, not 100% sure but I think so.

[Frosti]

@bower The curious thing is that my S. Habrochaites had no problem whatsoever with self pollination. However, the cross between S. Habrochaites (male) and S. Lycopersicum (female) barely worked. Maybe in the plants with poor pollination success, the pollen have Habrochaites characteristics and the ovaries are similar to the ordinary tomato?
Regarding the hand pollination of the symmetric plant ... so far it doesn't even form mature flowers, so there is nothing to pollinate.
Did you also notice with your determinates in low light conditions, that the leaves are much bigger? I definitely noticed this with Mexican Honey, which is usually an absolutely huge plant with gigantic leaves, but this year I put it in an extremely sunny location and the plant developed relatively small leaves.

[bower]

Hmmm @Frosti I didn't especially notice a difference in leaf size, so much as longer internodes and a tendency to linear growth habit, ie one shoot that just keeps going upward.
I should mention that the other difference this year, is that I had a lot of spotty leaves on the young plants before they went to the greenhouse, so all of the lower leaves were removed, more so than I normally would remove the lowest at planting time. So this may have affected the growth habit as well, although for certain the low light levels played the biggest role. I've seen this before in weather without sunshine - a bit of a specialty here.
Crowding may have played a part too, as that alone can drive a plant to grow taller as there's no room to bush out.

In other fruits, I recall reading that Calamondin was adapted to fruit in low levels of light, due to the volcanic activity in the region.
So I do think it's not unusual that fruit set (on various types of plant) can be poor in lower than normal light.

[Frosti]

Okay, so the tomato season has come to an end and it's time to draw a bottom line.
Of my 24 S. Habrochaites F2s only 2 had no issues with fruit set. The rest had at best one or two fruits here and there.
None of the fruits on any plant were yellow. They all looked most similar to the white to ivory fruits of last year's F1.
The Habrochaites line pattern was present on all of the fruits.
All fruits had varying degrees of S. Habrochaites flavor, which diminished the closer the fruits got to overripeness. In their ivory stage (overripe) the fruits were an acquired taste but one didn't have to immediately spit them out anymore.
The plant that was the most similar to the original S. Habrochaites in growth habit and leaf structure had lots of seeds within the fruits, while all the other plants had at most 1-4 seeds per fruit. It's very unlikely that that one has any dwarfism within it though. Speaking of dwarfism, all of the plants grew really tall (2.5m - 3m), despite my best efforts to select for dwarfism.
The subpar location of the plants allowed me to explore their disease resistance. While ordinary tomato plants had already succumbed to late blight right next to them, most of the S. Habrochaites F2s were unfazed. I think only one or two died prematurely. Mind you, these plants aren't immune to late blight, but they seem very resistant to it.

All in all these S. Habrochaites F2s turned out to be harder to work with than expected and I found myself wishing that actually tasty (and fruit bearing) tomatoes had occupied their places. Right now, I do not plan on continuing down this path, but it was an interesting learning experience and I hope you guys learned something as well. I took seeds from both fruit bearing plants of this line, so the door is open for a continuation of this line either by myself or by someone else.

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[bower]

It is a valiant effort @Frosti but I believe a lot of backcrossing may be the only way to get edible fruit from these interspecies crosses.
A lot of tomato growers had disappointing troubles in 2023. One disease or another, it was not a good year for many of us, and I'm glad to put the boot to the season and hope for better ones in future. It is sad though if a loved project gets abandoned because of the bad year.
All the same, I won't discourage you from working on crosses with more edible and productive tomatoes! Bring it on...

[Frosti]

@bower that's what I was thinking as well. If I ever resume this project I'll have to backcross at least once, probably twice.

[WilliamSchlegel]

I've been growing out Solanum habrochaites and crosses with it since 2017. The first few years I was just following along with what became Joseph Lofthouse's promiscuous tomato project. Since 2020 I've been growing and crossing with LA2329 Solanum habrochaites trying to recreate John Snyder's very interesting arthropod resistance work with it. Very interesting and very long-term projects!

[Frosti]

I've been growing out Solanum habrochaites and crosses with it since 2017. The first few years I was just following along with what became Joseph Lofthouse's promiscuous tomato project. Since 2020 I've been growing and crossing with LA2329 Solanum habrochaites trying to recreate John Snyder's very interesting arthropod resistance work with it. Very interesting and very long-term projects!

@WilliamSchlegel, that's very interesting, did you also have issues with fruit set?

[WilliamSchlegel]

Yes, for instance just this year I decided to isolate some F1 Big Hill x LA2329 and a line of mine I call Mission Mountain Morning X LA2329 crosses from my larger grow out of Promiscuous x LA2329 F1 and F2 and the smaller more isolated grow out produced zero fruit ripe or otherwise. The larger grow out, with some pure LA2329 in the mix, had plenty of fruit set.

Though even with pure LA2329 the first couple of years I grew it, only a few plants set fruit and the rest hopefully contributed some pollen.

The early generations of Joseph's crosses, perhaps partly because I grew fewer plants of them, had similar difficulties with fruit set. Fertility issues can be a real problem with Solanum habrochaites crosses.

[bower]

@WilliamSchlegel I didn't know that fertility was a problem.

What is the story on introgressed lines IL from TGRC? As I understand it, they are backcrossed to the tomato parent repeatedly and then selected and numbered based on testing for specific (and relatively small) genetic sequences which have been incorporated in a background of mostly tomato DNA. So they've already gotten them over the infertility/inedibility hump?

[WilliamSchlegel]

Hi Bower, yes that is correct- a great example is when Jim Myer's lab at Oregon State University was developing the blue skinned tomatoes. They started with introgression lines instead of having to go all the way back to the wild species. It is a much less involved way to access these genetics. Though as a botanist- I am quite fond of these green unpalatable wild tomato species- I think of them often as tomatoes that only a botanist could love. The introgression lines do represent much smaller chunks of the wild species genomes.