Breeding with wild tomato species

[Justin Jardinier]

I was reading this thinking: Can Solanum arcanum cross with Solanum peruvianum? Remembering something... Then I came back around to the groupings you made there Justin and I am not sure it can

Oh another point about this - whether or not there might be a small chance of them crossing, if corn. per. and arc. were grown together, it could result in a population of the following:
- per x corn and/or corn x per hybrids
- per
- corn
- arc

Depending on how compatible the corn and per accessions are with each other, there might not be any pure per and corn left, if they're compatible enough then I guess if the population is old enough there may be none left at all. But I am guessing there could be arc left that hasn't crossed at all, if it is competitive enough to remain in the population and not get entirely eliminated, which would be another possibility.

Still no word back on whether this population is the one being sold as 'Solanum peruvianum' by the EFN, and I don't mean to sound too critical, but if it is, then I do think it's unfair to sell it by that name if that's not what it is, even if once upon a time that name (or at least Lycopersicon peruvianum) might have applied, just as once upon a time S. galapagense and S. cheesmaniae, now clearly understood as different species, were both known as cheesmaniae.

Though perhaps it is a separate population - the EFN page certainly presents is as a species ("This is a wild species"), making clear it is not using the name in the sense of a 'species complex', and clearly treats corn. as a separate species, showing that it is indeed referring to the standard classification of tomato species, and explains that there there is merely "a possibility that some seeds might have been pollinated by S. habrochaites, S. pennellii, or S. corneliomullerii".

So not just the name but the description also, is not compatible with a deliberately combined population of 3 species.

[Justin Jardinier]

Theoretically hairy Solanum galapagense has stronger whitefly resistance, than non-hairy one.

I'm going to guess that you are relying on HRSeeds for (at least some of) your understanding of wild tomato species, which I would personally recommend against. I am also guessing that the galapagense that you may be referring to may be the one he has from the source from which I got it. And I am guessing that that might not be pure galapagense - on this last point I am less sure, but the emminent text 'TAXONOMY OF WILD TOMATOES AND THEIR RELATIVES (SOLANUM SECT. LYCOPERSICOIDES, SECT. JUGLANDIFOLIA, SECT. LYCOPERSICON; SOLANACEAE)', Iris E. Peralta - 2008, states that galapagense is "densely pubescent", and I have found that to be so with all of the 5 genebank galapagense accessions I have grown. Unless I have overlooked something in that text, there is no mention of any non-pubescent galapagense, and that description seems intended for the species as a whole. Furthermore the paper 'Genetic Diversity and Population Structure of Two Tomato Species from the Galapagos Islands', Yveline Pailles et al - 2017, notes that there is "little genetic diversity within this species". Which makes me suspect that that non-hairy one may be a galapagense-cheesmaniae hybrid.

One thing I did find interesting about it was that the fruits seemed to have a lot of anthocyanin in the skin. Of the known pure accessions I grew, some had none, some had a few antho speckles or even a bit of a speckled stripe in similar configuration to the stripe on some wild green species, but fainter. So I find that antho quality potentially valuable, but in all other respects I preferred the known-to-be-pure accessions, such as the strong stem, denser growth habit, stronger smell, and hairs.

The text above is available online. I highly recommend it.

[Alex]

Possibly non-hairy Solanum galapagense is a natural hybrid. If we assume that pure Solanum galapagense is exclusively hairy, then how could it be confused with Solanum Cheesmaniae and attributed to the same species Lycopersicon cheesmaniae var. minor?
I have 2 samples of non-hairy Solanum galapagense from HRseeds, US and France.

[Alex]

Is it really Lycopersicon hirsutum f. typicum https://www.hrseeds.com/product-page/wild-hairy-tomato-type-2 ? Plant is not hairy on pictures, but typicum is hairy plant: http://unusualediblesandtheirwildrelatives.blogspot.com/2017/11/wild-tomatoe-species-lycopersicon-spp.html . Who is right?

[Justin Jardinier]

If we assume that pure Solanum galapagense is exclusively hairy, then how could it be confused with Solanum Cheesmaniae and attributed to the same species

People make mistakes. Also I was not suggesting it's cheesmaniae, I was suggesting it may be gal x che or che x gal.

I have 2 samples of non-hairy Solanum galapagense from HRseeds, US and France.

I assume HRSeeds sourced his from Lupinaster. Perhaps the French source also did? Do they seem to be the same variety phenotypically?

Is it really Lycopersicon hirsutum f. typicum

That is an old classification system, I don't know why Wojciech uses that system but that must be why HRSeeds is using it I would guess, since most or at least many of his wild tomatoes come from Wojciech. Wojciech is anyway a more reliable source of information and seeds in my opinion. Solanum habrochaites is the current name of that species. There are 'glabrous' and 'typical' populations. The text I recommended to you states:

Pubescence in S. habrochaites is quite variable, and Müller's (1940a) forma glabratum includes plants that are not strictly glabrous, but only have fewer of the longest trichomes on all parts (Fig. 29).

I'm no expert and have very limited experience with habrochaites, but yes to me those leaves do not look hairy, so your doubts might be well founded. Here's a photo of hab LA1777 in case that helps - very clearly hairy leaves and stem:

[William Schlegel]

Go easy on the seed suppliers. They are pretty scarce.

[Justin Jardinier]

I did not mean to be rude. Just that since I have noticed numerous errors on HRSeeds website, it seemed appropriate to warn someone trying to learn about the specifics of different species. I hope that wasn't inappropriate. I would not have been able to tell the issues had I not spent a lot of time studying, and I expect many won't have the time to do that, so, just trying to give people shortcuts to knowledge by suggesting reliable sources of info. And aside from issues of many crushed seeds, I do feel as I have mentioned, that HRSeeds is also a valuable resource. That galapagense for example, even if it is not pure, the antho quality could be very valuable. And his gal x lyc is really nice, delicious.

I can be a bit blunt if I see errors. I prefer if information is correct, and sometimes say things out aloud on the assumption that others might feel the same, with the intention of benefitting the community. I think HRSeeds' unresponsiveness to being privately contacted about some of his errors encourages me more, since I know how it feels to be eager to obtain specific seeds and how it feels to be misled. Sorry if that ever comes across as seeming rude.

[William Schlegel]

I try to save seed from the wild species and or make crosses with them every year. It's difficult- I think is my point. HRseeds is a valuable resource as is Joseph's peruvianum or peruvianum cross grex. The guy who does HR seeds is just one individual and is doing some remarkable work even growing out and producing some seed for the more difficult species from that perspective. Especially when he is also growing so many domestic varieties. Joseph was doing a very large scale operation for a single seed farmer for many years. I do what I can part time and I always plant too much. You've done some remarkable crossing! I know youve been putting in long hours on it! It's all a lot of work!

Thought going around in my head- wild to wild crosses and high percentage wild to domestic crosses are another way to preserve some of this germplasm if we can get to tasty endpoints. The global tomato community preserves thousands of tomato varieties- tasty varieties can kind of slide into that system and people will hopefully value and reproduce them. If they are more diverse at the genetic level it will help with the basic problem of lots of morphological diversity but little genetic- like for instance how popular the blue skinned tomatoes became!

Though on a related note. Accessions from TGRC carry a material transfer agreement that does not carry over to new crosses- including presumably wild x wild crosses. So developing new crossed wild or high percentage material can also, in some cases, be a way to free the material from an MTA. That resulting material though may still be far from ready for breeding a finished polished widely adoptable tomato.

[Alex]

I was suggesting it may be gal x che or che x gal.

hybrids between S. galapagense and S. cheesmaniae have been found (Darwin et al., 2009)

Do they seem to be the same variety phenotypically?

They are too small, I let you know if they grow.

[Cathy A]

I do think that those accessions I've obtained are declining in quality as they go through generations under my care... Even at the professional seed banks there is some concern that these wild accessions are slowly declining in quality- that is one reason why they are increasingly reluctant to share seed with independent plant breeders.

William, what is the cause of the decline in quality? Not enough roguing of off-types?  Insufficient isolation?

Is there anything that small scale plant breeders can do to stabilize or improve quality? Or is this just something that requires more time, resources, and effort than amateurs or small-scale seed growers can provide?

[Alex]

HRSeeds is good resource of wild tomato seeds and their hybrids. Sometimes they have interesting their own seeds. For example, red arcanum https://www.hrseeds.com/product-page/solanum-arcanum-red-tomato-hr "This is a strange one, one bract on a Solanum Arcanum plant made red tomatoes! It is NOT a hybrid or cross of any kind it just simply put out a red variation of Solanum Arcanum."
Why did it happen? Was it mutation or not pure parent? Any suggestions.

[William Schlegel]

William, what is the cause of the decline in quality? Not enough roguing of off-types?  Insufficient isolation?

Is there anything that small scale plant breeders can do to stabilize or improve quality? Or is this just something that requires more time, resources, and effort than amateurs or small-scale seed growers can provide?

Genetic drift! I think is the number one cause of decline. Even with the TGRC accession grow out protocols that are designed to minimize it. Optimum conservation of populations would be In Situ + Ex Situ conservation. Without further access to the wild In Situ populations the research and breeding populations at the gene banks will eventually no longer be representative of the wild resource. If the species all survive in the wild. All the populations likely will not.

[Joseph Lofthouse]

I lump things together. My population of Solanum peruvianum contains all the genetic diversity that I could add to it. Just like every other species that I grow.

I do not believe in the arbitrary concept of "species". Capriciousness seems like the defining trait of biological systems, especially among arcanum, cornelliomulleri, and peruvianum, which seem more alike than different. Considerable ambiguity exists in the literature regarding how to distinguish one species from the other, and depending on location, they inter-cross freely. Genetic analysis of some arcanum populations classifies them as peruvianum.

When I take calipers into my garden to measure traits objectively, they exist on an indiscreet spectrum, not distributed into distinct phenotypes.

My varieties came to me, long ago, using an archaic taxonomy system from a foreign land. They might not necessarily line up with current mainstream taxonomy. Additionally, I acquired some of my peruvianum seeds from my mentor Alan Kapuler, who values kinship gardening.

A long-winded way of saying that biology approximates a gray-scale rather than black or white.

[Justin Jardinier]

Is there anything that small scale plant breeders can do to stabilize or improve quality?

From what I understand (I think it might have been William I learned this from?), whilst population sizes are critical for maintaining wholly or partly outcrossing species, once doesn't need to grow them all at once. For example, to maintain an accession, the TGRC recommends minimum population sizes of 75 plants for SI species. For some reason it also recommends 75 for chmielewskii which is facultative SC, and for facultative SC populations of pimp, but just 15 for facultative SC populations of habrochaites. And 6~9 for autogamous SC populations/species.

75 is a lot, but you could grow some one year, some others from the original seed packet the next, and so on until you have met or exceeded 75, and then combine the seeds from all of those years. There may still be some loss due to the difference in climate, but this seems like something we can do that helps maintain as much diversity as we can. That's something I worry about from some sources, what kind of bottlenecks some growers put the seeds through. If wanting to maintain or create an SI population, that seems an important concern. Though if one is just wanting to use a variety for crossing with in the creation of a new SI tomato line, I guess that's not really an issue.

[Justin Jardinier]

I lump things together. My population of Solanum peruvianum contains all the genetic diversity that I could add to it. Just like every other species that I grow.

I do not believe in the arbitrary concept of "species". Capriciousness seems like the defining trait of biological systems, especially among arcanum, cornelliomulleri, and peruvianum, which seem more alike than different. Considerable ambiguity exists in the literature regarding how to distinguish one species from the other, and depending on location, they inter-cross freely. Genetic analysis of some arcanum populations classifies them as peruvianum.

When I take calipers into my garden to measure traits objectively, they exist on an indiscreet spectrum, not distributed into distinct phenotypes.

My varieties came to me, long ago, using an archaic taxonomy system from a foreign land. They might not necessarily line up with current mainstream taxonomy.

Though you have not answered directly, I take this to mean that the population you have described is the same one sold by the EFN as Solanum peruvianum. Please correct me if I am wrong in that assumption.

Personally, the issue I see with that is that while privately you do not believe in the arbitrary concept of "species", the public do, and the product is clearly described on the basis of that consensus belief, explicitly describing it as the specific single species Solanum peruvianum, and explicitly differentiating that from other species such as Solanum corneliomulleri (which it implies there is only a small chance that some might have accidentally crossed with, and no mention of arcanum at all), making it clear that the description is on the basis of the current accepted species classification system, as used by the TGRC and so on. It does come across to me that you differentiate them yourself in some way at least, since you wrote "Corneliomulleri, peruvianum, and arcanum seem so closely related that I combined the populations in my garden." I personally feel that there is nothing inherently wrong with you seeing the differences between them but not personally labelling them as different 'species'. But I would personally think that it would be more transparent to describe them as a combined population of those species (as you have done here) when they are being sold to the public, or explaining that you are giving them that name but it means something different to you than it does to the rest of the world and saying what that is; rather than they being sold specifically under the name Solanum peruvianum, accompanied by the description they have which makes explicit that that is indeed the specific species as understood and agreed upon by the current classification system.

I feel like I sound like I'm telling you off or something, and I don't want that, and I do apologise if any of this seems rude. I am just trying to express that personally, if I am sold something I want it to be what it is described to be, rather than something quite different from what it is described to be. And I do believe that many people feel the same way in that regard. I know there are people who are upset by sellers knowingly selling 'Solanum cheesmaniae' when it is actually hybridised with other species, for example. Another example would be if I use mass pollen from what I believe to be a pure peruvianum population, on plants I know are compatible with arcanum but am trying to cross them with peruvianum, this process is ruined if the peruvianum population is contaminated with arcanum, because a successful result may in fact be from an arcanum plant (that itself might never have crossed with any per or corn), because instead of making a successful cross with peruvianum, it may just be a cross with arcanum. This in my case is extremely important in my current project, and I may potentially have encountered this specific problem. So I am not just talking theoretically - this is a practical issue for me, that can cause significant issues.

I guess I am just making a plea that products have true descriptions. A plea for transparency. The seeds are wonderful and precious. Many might even prefer them for what they are rather than what they are being advertised to be. But if they are described to be what they actually are, at least people can know what they are buying - that's my point really, that's all I wanted to express.