Breeding with wild tomato species

[Kadence Luneman]

I just had a thought on wild tomatoes being known to be harder to germinate and get started.
Aren't wild tomatoes eaten alot by birds in the native ranges? When multi flora rose was introduced in the USA with the aspirations of hedges/living fence it was said to not be able to spread. Of course it does spread! But in a lab it did not. In nature birds eat it and spread the seeds which have now been scarified (?) by the birds digestion.

After a quick search it seems that chickens poop out what they ate about 4 hours ago.
It would be a really interesting experiment to take a chicken in a single pen and feed it some ripe wild tomatoes. Collect the manure for that day, mix it with soil, and see how much tomatoes grow from it.

Obviously not very manageable just to grow wild tomatoes 😂 but I think it would be interesting to see if the seeds did better after that kind of treatment.

[Kadence Luneman]

What are your thoughts on earliness? I like the idea of Galahad more than Purple Zebra since Galahad is homozygous for PH-2 and PH-3, whereas P. Zebra is heterozygous. But both of them may be rather late season, I think perhaps P. Zebra later than Galahad also.

I'm planning on doing crosses with micro dwarf tomatoes like rosey finch, which is supposed to be 55 days from seed.
It's not using wild tomatoes but perhaps it would be worth trying something like rosey finch x Galahad. Select for earliness. And then continue with those offspring crossed to each other and/or back to Galahad. Trying to get earliness and as much of the resistances as possible.

[Kadence Luneman]

I have a working list of which crosses I think I want to prioritize. As far as wild genetics goes would it be useful to decide on some of the best Wildling plants and make crosses of them and the Improved Galapagos, since they should already have some pennellii and habrochaites?

[Justin Jardinier]

I just had a thought on wild tomatoes being known to be harder to germinate and get started.

I haven't really noticed wild tomatoes being much harder to germinate than domestic tomatoes, not that I noticed anyway - aside from galapagense and cheesmaniae. Bleach does help them. Bleach seems to help ungerminated seeds from some other species too. It might just be about pH? There were some other wild seeds where for those that didn't germinate, I soaked them in a bleach solution and then they germinated, so that's an option too. That might even be preferable for all wild species, like Joseph did, selecting for seeds that don't need bleach - maybe try first without, so that if enough germinate without bleach, you can keep going that way, thereby selecting for not needing it, but if not enough germinate, then falling back to the bleach method. This would be harder to do if you're germinating in soil but if you germinate on paper (whether in a humidity box or in a plastic bag) then this should be pretty easy.

Also, I got away with using considerably weaker bleach solution than the TGRC protocol, and usually just for 15 minutes or so. It might be worth experimenting with those variables, if you wish to aim for less bleach. It could also be worth experimenting with other pH protocols, if you wanted to try more natural forms of acid or alkali. I even wondered about letting fruits rot - I noticed a smell of ammonia in some rotten fruits where fruit flies have been busy, and wondered if that might have a similar action. It could be interesting to see if seeds from that could then be germinated straight away, or perhaps even left for the fruit to be eaten away and dry, then germinate next season - I have no idea if that process would make them able to germinate the next year easily, or if they'd. have to be germinated straight away, but it might be worth experimenting with. Or the chicken poop idea might be similar in that respect. Worth a try!

Then regarding harder to get started - that might be to do with small seed size. They have less energy stored, so they will be slower to start. The increased seed size is a domestication trait.

It's not using wild tomatoes but perhaps it would be worth trying something like rosey finch x Galahad. Select for earliness.

Sounds good! I hope it goes well!

As far as wild genetics goes would it be useful to decide on some of the best Wildling plants and make crosses of them and the Improved Galapagos, since they should already have some pennellii and habrochaites?

So far as I understand, Joseph's galapagense is pure galapagense, no pen or hab in them. I don't know of anyone in the US other than Joseph via the EFN, and HRSeeds, selling galapagense. So yes that sounds like a nice idea.

Also HRSeeds sells 2 types:
- Galapagos Wild Tomato Hairy Strain (Minor) Type 1
- Galapagos Wild Tomato Minor Type 2

For the second, he writes:

There are also 2 variations of the minor, a hairy type (1) and a non-hairy type (2). This listing is for the minor (Solanum galapagense) non-hairy type (2) variety.

I have found absolutely no evidence of this being true, but rather a lot indicating that it is false, specifically that all galapagense are hairy. That also has significantly different growth habit to all galapagense I have ever grown or seen photos of in genebanks. I suspect that is a hybrid of galapagense and cheesmaniae. I did question the person whom he appears to have got that information and seeds from, and that person turned out to have no real basis for that identification and explanation, and it was directly contradicted by the source he was relying upon for identification, which further supported my suspicions. That is not to say that it is not a valuable plant. I just don't believe it is what it is claimed to be.

If you have access to genebanks, then you might want to select a galapagense that has larger flowers and with stigma exsersion, if you value exsersion. That has been my preference anyway. But it might not matter that much - I actually don't know, but crossing exserted Wildings with Joseph's galapagense should surely be worth a try. Also I doubt there would be any issue with germination in galapagense crosses as there is with pure galapagense, I personally had no such issues with many F1 crosses nor with someone else's F2. So I would not worry about that trait if your purpose is crossing. But it's a useful trait if you want to grow just the pure galapagense.

In the event that you do have access to genebanks, I would recommend LA0317 for flower size and exsersion. (There might be better choices out there but that's the best I have experience with for those traits). I would also recommend LA1400 - I do not know about the flower size or whether the stigmas are exserted or not, but it scored 20% in disease severity in ToBRFV trials, which is remarkable - so far as I remember the next best performance for galapagense accessions was 60%. And while ToBRFV might not be an issue now, there seems a fair chance that it will be in the future. If I had access to LA1400, I would use it, potentially as my first choice even if it is not exserted, since I think including some ToBRFV resistance even if not testable at the moment, could prove very useful in future.

[Alex]

I suspect that is a hybrid of galapagense and cheesmaniae.

Seeds are too big for this. If to look at hybrids between hairy and "non-hairy" galapagense, then they have some lycopercicum genetics and size of seeds confirms it. So it's a mix of different tomatoes.

[Justin Jardinier]

Seeds are too big for this.

What length width and depth did you measure them to be?

[Alex]

And his gal x lyc is really nice, delicious.

Very fragile plants, 50% damage after strong wind.

[William Schlegel]

https://onlinelibrary.wiley.com/action/downloadSupplement?doi=10.1111%2Ftpj.12616&file=tpj12616-sup-0001-FigS1.pdf

https://onlinelibrary.wiley.com/doi/10.1111/tpj.12616

I really like table S1 from the above paper. It shows the distance of a number of species and specific accessions from a reference genome in terms of the number of single nucleotide polymorphisms.

https://arxiv.org/ftp/arxiv/papers/1504/1504.05610.pdf?fbclid=IwAR18nMY4uS9pGNpnOXlf4PATvAv7Tvst187GNsGZ4HJ6KjJ0oU7lgaIYs5M In this preprint version there is a caption which explains that the reference genome is of Heinz 1706

https://tgrc-mvc.plantsciences.ucdavis.edu/Accession/detail/LA1479  So LA1479 a Solanum lycopersicum var. cerasiforme from South America is an impressive four million SNP's away from the standard Heinz 1706. A typical Solanum habrochaites accession comes in at around eight million SNP's of difference. A very interesting figure and I think it illustrates well why we might want to use wild species and domestic tomatoes from South America in breeding.

[Justin Jardinier]

I was just reading this article yesterday. I did not notice until now it uses the expression 'peruvianum complex', though only once, and without explanation, merely saying:

Here, we placed both accessions into the Arcanum group with 'northern' species of the peruvianum complex.

I don't even see the use of such a category in any of the diagrams in the paper, though I have not yet looked through all of their supplementary material. It seems strange for them to still be using RIck's old system of dividing tomato species into those 2 categories, 'Esculantum complex' and 'Peruvianum complex', especially since he put chielewskii and neorickii in the former, but they're claiming arcanum, it's ancestor, to be in the latter. Though since it seems to be the only mention of the term, perhaps it was a slip up somehow, perhaps due to the large number of authors.

I was reading another paper on arcanum yesterday, Population Genomics of the Arcanum Species Group in Wild Tomatoes - Evidence for Separate Origins of Two Self-Compatible Lineages - Ana M. Florez-Rueda et al - 2021:
https://www.frontiersin.org/articles/10.3389/fpls.2021.624442/full

If anyone is interested in a more detailed placing of this species in relation to the rest of the arcanum group, and the separate emergence of S. chmielewskii, and S. neorickii, rather than neorickii having evolved from chmielewskii as was formerly believed, it's an interesting paper. It references this paper in fact:

Previous genome-wide molecular analyses of the tomato clade did not allow definitive conclusions about the status of S. arcanum because only one (Pease et al., 2016) or two (Aflitos et al., 2014) plants were sequenced. In the latter case, inclusion of accessions LA2172 (MARA) and LA2157 (var. "chotano") hinted at a heterogeneous assemblage and the paraphyletic nature of S. arcanum, but only the inclusion of more accessions across the entire group allowed us to make more robust inferences.

I realise my comment might sound a bit negative - it's not meant to, that's just what I thought might be useful for me to add to this topic. I am looking forward to digging deeper into the paper for useful info.

https://tgrc-mvc.plantsciences.ucdavis.edu/Accession/detail/LA1479  So LA1479 a Solanum lycopersicum var. cerasiforme from South America is an impressive four million SNP's away from the standard Heinz 1706. A typical Solanum habrochaites accession comes in at around eight million SNP's of difference. A very interesting figure and I think it illustrates well why we might want to use wild species and domestic tomatoes from South America in breeding.

Anoher interesting thing about that is that that accession is from Sucúa in Ecuador. The paper Variation Revealed by SNP Genotyping and Morphology Provides Insight into the Origin of the Tomato -Jose Blanca et al.- 2012 mentions that location numerous times, for example:

Despite the abundance of admixture in S. l. cerasiforme, not all accessions belonging to this variety appear to be the result of an extensive hybridization process. For instance, the accessions from the Sucúa region in Ecuador and some from San Martín in northern Peru do not seem to be admixtures according to the Structure analysis, although in several a small contribution of the northern Ecuadorian S. pimpinellifolium genome could be detected. If we ignore the clear southern Peruvian admixtures, the Sucúa accessions are also the closest S. l. cerasiforme accessions to S. pimpinellifolium in the PCA. Both their lack of admixture and their closeness to the wild species might indicate that the S. l. cerasiforme accessions of the Sucúa region might be similar to the S. l. cerasiforme that inhabited the region before foreign tomatoes arrived in the Andean region. It is remarkable that the S. l. cerasiforme from this region also has high polymorphism and high heterozygosity that are equivalent to those found for S. pimpinellifolium in Piura, its region of maximum variability and allogamy [23,24].

It really looks like an interesting area for tomatoes to breed with.

[William Schlegel]

I don't even see the use of such a category in any of the diagrams in the paper, though I have not yet looked through all of their supplementary material. It seems strange for them to still be using RIck's old system of dividing tomato species into those 2 categories, 'Esculantum complex' and 'Peruvianum complex', especially since he put chielewskii and neorickii in the former, but they're claiming arcanum, it's ancestor, to be in the latter. Though since it seems to be the only mention of the term, perhaps it was a slip up somehow, perhaps due to the large number of authors.

I've heard and used the term "Peruvianum Complex" to refer to S. peruvianum, S. chilense, S. arcanum, and S. cornelio muelleri in the past (might be missing some). I don't think these authors necessarily were going all the way back to a system Rick developed.

However, I was looking on TGRC's website Key and there is a link that leads you to the Tomato Genetic's Cooperative's pdfs of which volume 40 from 1990 has a key which seems to indicate that at that time peruvianum complex only referred to S. chilense and S. peruvianum of which S. arcanum and S. cornelio muelleri had not yet been divided out from S. peruvianum. Though that key mentions an even earlier key in volume 27.

https://tgc.ifas.ufl.edu/onlinevo.htm

Um, there is very likely an interesting gold mine of tomato information in all these tomato genetics cooperative reports.

[Justin Jardinier]

I've heard and used the term "Peruvianum Complex" to refer to S. peruvianum, S. chilense, S. arcanum, and S. cornelio muelleri in the past (might be missing some). I don't think these authors necessarily were going all the way back to a system Rick developed.

I wondered if they might actually be, since the only other mention of that concept in their paper was among the references:

Rick, C.M. (1986) Reproductive isolation in the Lycopersicum peruvianum complex. In Solanaceae: Biology and Systematics ( W.G.D. D'Arcy, ed.). New York, NY: Columbia University Press, pp. 477–495.

But I was guessing it might have just been a slip up from the vestiges of the old way of thinking, before so much research (including this valuable paper) had been done, perhaps. No big deal though.

I was thinking about the crossing behaviour with arcanum though. Obviously we now (including in that paper) put arcanum in the 'Arcanum group' with chmielewskii and neorickii, and separate from that we have the 'Eriopersicon group':
S. habrochaites
S. chilense
S. huaylasense
S. peruvianum
S. corneliomulleri

They follow Peralta on that. But I was wondering about the crossing... I've managed to use arcanum as a bridge for peruvianum, so, it made me curious about the evolutionary history. In answer to this, I found Peralta saying this in the arcanum chapter:

This variability and apparent morphological intermediacy led Rick to include populations now recognized as S. arcanum as part of a broadly constituted S. peruvianum (as Lycopersicon peruvianum). The northern populations of Rick's L. peruvianum, now recognized as S. arcanum, have complex crossing relationships with more southerly populations of S. peruvianum s.l. and with S. chilense (Rick 1963, 1986a). Because these northern populations could be crossed successfully with S. chilense but not with S. peruvianum s.str., Rick (1986a) suggested that they were ancestral to the rest of the "peruvianum complex," and that northern Peru was a major site of evolutionary development in the wild tomatoes.

And:

Because accessions we now recognize as S. arcanum did not cross successfully with either S. chmielewskii or S. neorickii (Rick et al. 1976), Rick believed that they were not closely related. As we noted above, we do not feel crossability is a reliable indicator of relationship in the tomatoes and their relatives.

That has helped me to understand, and makes sense to me.
It's quite amazing really, how we are able to cross such a variety of species. There is such a wealth of genetic diversity at our disposal!

[Alex]

14. J.F. Macbr's Wild Tomato - Solanum corneliomulleri. The leaves remind me of S. habrochaites. The fruits are green, seem maybe hairy like habrochaites. Says self compatible.

I grew it and in my opinion it is not S.corneliomulleri, but a self-incompatible hairy tomato S.habrochaites.

[Alex]

Do they seem to be the same variety phenotypically?

No. The tomato from France turned out to be a fake tomato, some kind of S.galapagense hybrid, it lived with me for six months, was 0.5 meters, never bloomed and dried out. The non-hairy S.galapagense tomato from HRSeeds did not survive for me, the likely reason is the loss of heat resistance in Poland.

[William Schlegel]

I grew it and in my opinion it is not S.corneliomulleri, but a self-incompatible hairy tomato S.habrochaites.

Interesting result. I don't think HR seeds has the ability to isolate and habrochaites is compatible with some of the other SI species. My own working collection of wild tomatoes I don't usually isolate when I grow out so any compatible species could cross. I would welcome such crosses as they could lead to potential bridging.

I was looking up a accession of a new to me species I got in a seed trade on TGRC's website under its accession number LA1028 chimelewski and it looks so much like the peruvianum and arcanum I've been growing that I was surprised. I wouldn't be able to detect natural crosses between those three necessarily. Certainly not without careful use of the TGRC species key and hybrids you really need a description not just a key. If I was able to detect the crosses I would share them as crosses. The corneliomuelleri I got from Joseph 7 years ago we thought had crossed with the peruvianum.

[Justin Jardinier]

The seller also doesn't seem to have noticed that 'Macbr' is an abbreviation of the name Macbride! Also from his photographs - from my personal notes I wrote "I wonder if he has actually misidentified this, the leaves don't look right, maybe this is actually peruvianum or arcanum?" and a professor friend did also say he thought it looked like habrochaites though later thought perhaps arcanum. I did write to him about it (and some other misidentification he made) but there was no response. Perhaps it is indeed habrochaites in the end then!