Solanum pimpinellifolium Currant Tomatoes

[William Schlegel]

Just a note: my F1 pimpinillifolium crosses I grew out in 2023 were both tasty red cherry tomatoes. I made ~3 such crosses in 2022 with two accessions of pimpinillifolium from the USDA ARS GRIN system. One of which might be the source of PH5 LB resistance and the other of which is known for Brown rugose resistance. Next year it will be fun to see how the F2s segregate.

[Garrett Schantz]

To my understanding, once a domestic tomato crosses into a Pimpinellifolium, it's then considered to be a Solanum lycopersicum type of thing.


White Currant, Florida Everglades Currant - and others, were likely crossed with domestic tomatoes, accidentally or not.


Pimpinellifolium types usually have a trait which let's them outcross to a small extent.


Companies have thus usually only sold stable crosses.



Spoon tomato, may be a actual Pimpinellifolium.


Wild Currant Tomato From Peru, and Alberto Shatters are true Pimpinellifolium types.


But, frankly speaking. Domestic tomatoes wild ancestors are Solanum pimpinellifolium.

For some reason, they're marked as different species.


Marking something as Lycopersicum x Pimpinellifolium, seems tedious and unnecessary if the crosses are stable.


So for this topic, maybe just considering small, Currant sized tomatoes as Solanum pimpinellifolium will work, even if they're hybrids.


I'd discount them from the group, if they're something like Dancing with Smurfs. Anthocyanin colors on the fruits, usually means there's wild genetics from another species and thus definitely not pimpinellifolium.


There are a ton of Currant tomatoes online, it's probably a safe assumption that none of them are purely Solanum pimpinellifolium.


But, just calling the name, rather than "Currant" or whatever may work out well. There honestly usually isn't a big difference.



I really like the Wild Currant Tomato From Peru. Not a great name for it.


It tastes like nothing. I bite into the things, and they taste like watery shells with a tough skin. Pea sized, full of water.


Decent amounts of slightly exserted flowers.

I'd prefer to select for smaller fruit / seeds, to facilitate better crosses with other species.


I've also noticed something with the wild landraces.


There's the need of weeding out the small fruited genes, and some incompatibilities.


With them, I just need to select for disease resistance, seed size and whatever else.


Larger tomatoes also usually have bigger seeds.


So, a very exserted group of plants, and just select for disease resistances. And then also select for SI plants.

Maybe make sure they can cross into larger fruited tomatoes as well.


But yeah. I'm not sure if people here categorize the species based on origin or if any domestic hybrids get discounted as a non pimpinellifolium.

[Justin Jardinier]

To my understanding, once a domestic tomato crosses into a Pimpinellifolium, it's then considered to be a Solanum lycopersicum type of thing.

Marking something as Lycopersicum x Pimpinellifolium, seems tedious and unnecessary if the crosses are stable.

Personally I think if something is half half, it's worth noting that. Half is a lot!

There are a ton of Currant tomatoes online, it's probably a safe assumption that none of them are purely Solanum pimpinellifolium.

I noticed the seeds of so-called pimps from HRSeeds are large and so I expect them to be at least half lyc. And I reckon going by seed size is probably the easiest way of telling if a pimp is pure or not. But I did encounter a curious thing - of the 4 genebank pimps I have, one has somewhat larger seeds, not as big as lyc but bigger than standard wild species. That made me suspicious so I asked them and they at least seemed sure it was pure. Growing them out, the fruit size is consistent with the surely pure ones, but, it's the only hairy stemmed one! That increased my suspicions. So, do you guys know of any surely pure pimps that have hairy stems? I don't mean hairy like LA1777, just in the normal lyc way. Mention above of hairy pimp fruit got me thinking about this also. But I would not be surprised if it may have a bit of lyc in it, though, perhaps there really are wild pimps with somewhat larger seeds...

[AndrewB]

The Solanum cheesmaniae galapagose tomato sold by Terrior Seeds / Underwood Gardens likewise is not pure and some sort of wild x domestic hybrid. I still really like it, but they refuse to accept to post my reviews that state it is not pure.

[Justin Jardinier]

Yeah, same for HRSeeds' 'Galapagos Island Tomato #2'. He states:

Here is the Galapagos Island Tomato #2, Solanum cheesmanii. This is another variation of the Galapagos Island Tomato. Tho there are only 2 endemic species on the Galapagos Islands, There are several variations of each species. Some of the them are natural hybrids that crossed with solanum pimpinellifolium which are an invasive species in the archipelago. This variation seems to be from the original plants on the island. Some of the tomato plants there can be decades old with wooden trunks and still produce fruits even to this day! Open pollinated Indeterminate mid season regular leaf 65-85 days.

But from seed size, fruit size and fruit shape, I'm quite sure it is a lyc hybrid. I wrote to him about several of his apparent misidentifications but got no reply. You really have to be careful with seeds being sold by people! Also while some cheesmaniae hybrids apparently taste good, like the one you mentioned, this one doesn't, in my opinion. Though his gal x lyc (listed as 'Galapagos Minor Cherry Tomato F2') tastes really nice, and has quite good fruit size! Also didn't get late blight though did crack after heavy rain (I only grew 1 so this is not a comprehensive report).Though also, many of his seeds of various types failed, seems they were crushed, perhaps either due to the way he processes them (blender?) or due to lack of care in packaging.

[William Schlegel]

Some gene bank accessions probably are mixed but wild collected and carefully kept pure since accessioning. Because of gene flow with domestics before collection and accessioning.

Normal part of wild crop relatives, if near humans is bilateral gene flow between wild and domestic populations. My source for that thought is one of my favorite authors Gary Paul Nabhan. He explores the idea extensively over multiple books.

Also, it is possible that some Lyc genes were already present in some wild pimp populations before domestication.

I wonder how divergent lyc and pimp really are. May depend on the population of pimpinillifolium.

Somewhere there is or was likely a source population.

I had to re-evaluate what I thought pimpinillifolium was while growing the two wild gene bank accessions I grew last year. Their leaves didn't seem like what I thought of as typical pimpinillifolium. This could be contamination or gene flow with domestics before accessioning but it could also be variation within a diverse wild species. Lyc had to come from somewhere after all.

I agree that half Pimps are worth noting. I also think any tomato of near current size likely has a lot of pimpinillifolium or other wild tomato in its genetic background. I was very intrigued recently to learn that the heirloom tomato Farthest North bred in North Dakota is a pimpinillifolium cross. I remember speculating back in 2017 that it seems like all very early tomatoes had some pimpinillifolium like characteristics and now I know that a lot of the more recently bred in North Dakota, Idaho, and Alberta have Farthest North in their pedigrees- so probably a lot of early tomatoes with unknown pedigrees have pimpinillfolium too. I don't think that means no further crosses with pimpinillifolium are needed though because their is a lot of diversity spread across lots of accessions there containing potentially useful traits. Also most modern tomatoes have significant large pimpinillifolium and other wild species introgressions for specific resistant traits.

[Garrett Schantz]

Yeah.

HRseeds does mention in some of his listings, that some of his Galapagos Island seed came right from the Islands.


But, Pimpinellifolium and some probable cherry tomatoes are invasive there.



They cross with back and forth with Cheesmanii and Galapagense.


Birds are reported to favor orange fruits, and so that's what they mostly eat. Many tomatoes end up becoming predominantly orange tomatoes throughout a large area as usual.

Single areas can have a ton of domestic hybrids just dropping and seeding.



I'd also assume that like William has said, this happens with Pimpinellifolium and Lyco as well.


The Galapagos Islands just happen to be well maintained and studied. Besides the whole thing with overfishing being allowed.

[William Schlegel]

It occurs to me, after looking at some somewhat mysterious current and cherry tomatoes in my garden this morning, that it is certainly plausible for current size red tomatoes to arise entirely from hybridization with Solanum habrochaites or another green unpalatable species and domestic tomatoes.

[Justin Jardinier]

Some gene bank accessions probably are mixed but wild collected and carefully kept pure since accessioning. Because of gene flow with domestics before collection and accessioning.

Yeah that makes sense. Probably not a bad thing since it seems some of those pre-colonial landrace tomatoes they might be crossed with have maybe greater disease resistance than the European ones?

Also, it is possible that some Lyc genes were already present in some wild pimp populations before domestication.

That would seem to imply you don't think lyc resulted as the domestication of pimp....? I would have thought that... most lyc genes were already present in wild pimps, no? Or, do you mean some domestic traits like bigger seeds? It would make sense that maybe some pimp populations has slightly bigger seeds and those ended up being favoured by the domestication process, maybe. I guess it might also be possible that some populations underwent partial domestication and were then given up on as human populations adopted better strains from neighbours. Though in my very limited understanding, I would guess maybe some amount of crossing to domestics somewhere along the line might be more likely. Though of course I really don't know. I wonder how long the seed size increase took in the domestication process?

I've also just had a thought - have any of you experience or knowledge of breeding with Andean landrace tomatoes? Perhaps we can gain a lot of genetic diversity and disease resistance by stepping back beyond both the European bottleneck and the bottleneck of the movement to Central America by looking at those, without having to step back prior to domestication, so as to keep the larger seed size and the relative size increase that they embody? I've made some crosses with Columbianum (a domestic landrace) but didn't grow it outside so not sure how it performs with the disease pressures here, though it's said to have some disease resistance.

Here's a couple of quotes from the paper 'Exploiting the diversity of tomato: the development of a phenotypically and genetically detailed germplasm collection'. N.B. abbreviations SP and SLC are referring to Solanum pimpinellifolium, and Solanum lycopersicum var. cerasiforme:

SLC has a worldwide distribution in tropical regions, but it is native to the Andean region of Ecuador and North of Peru1. This species is found over a vast range of environmental conditions such as tropical or arid regions, sea level or high altitudes23, and it has also been collected at native markets24. It usually bears red and small fruits, but Rick and Holle25 described a remarkable morphological variability in fruits, plant habit, or leaf size and shape. A higher genetic variability has been described in Ecuadorian and Peruvian accessions1,2 due to the development of morphological diversity during a pre-domestication phase. In fact, tomatoes collected in local markets of Ecuador were morphologically classified as vintage tomato; but they have been genetically classified as SLC3. These studies and data show that SLC from Northern Peru are very close to Mexican and vintage tomatoes. Despite that, Amazonian SLC has not been used frequently for tomato improvement as opposed to SP. Furthermore, SLC has been characterized as a valuable genetic source for abiotic and biotic stresses, such as moisture-tolerance26 or resistance to root rot caused by Phytophthora27; traits related with the global climate change and sustainability challenges currently facing agriculture.

Perhaps Peru and Ecuador could be the most promising source?

Genetic variability
As expected, the highest level of diversity was found in Peru and Ecuador for both SP and SLC groups2,3. Rick and Fobes1 described that variation in SLC depended on its geographical origin, being SLC from other countries less variable than SLC from these regions. The analysis within the SLC group also revealed a considerable decrease in the number of SNP variants detected in SLC Mexico. This is in agreement with the loss of variability that took place during the migration to Mesoamérica2,3,41. The detected 37,974 SNPs labeled as high impact show that this collection may be an interesting source of new alleles.

I tried searching for LB resistance in Andean landraces with no luck. But I did find the paper 'Assessment of Tomato (Solanum lycopersicum) Landraces for Their Agronomic, Biochemical Characteristics and Resistance to Phytophthora infestans'. These are landraces from, forgive my copy and paste: AU−Austria; FR−France; GR−Greece IT−Italy; RO−Romania; RU−Russia; TH−Thailand.

From the supplementary table they have some with 'high' resistance to LB with fruits of 90~95g weight, and with 'very high' resistance up to 23g.

It occurs to me, after looking at some somewhat mysterious current and cherry tomatoes in my garden this morning, that it is certainly plausible for current size red tomatoes to arise entirely from hybridization with Solanum habrochaites or another green unpalatable species and domestic tomatoes.

One reason I was crossing pimp x pen was the idea of making small cherry tomatoes only by combining wild species, avoiding lyc altogether. I could imagine various complex combinations using pimp, chm, pen, gal, and che. I'm now growing out:
pimp x pen
pimp x arc
pimp x chm
che x chm
gal x pen (waiting to germinate)
gal x chm

Already made cross attempts between some of these amongst each other and back to gal and che. And might have some gal x hab crosses coming if my cross attempts succeed.

Two thoughts on that though:
1) The only parents among those that impressed me against LB was arc.
2) It could be handy to have at least some lyc in the mix to gain larger seed size. I'm growing out various lyc crosses such as lyc x gal (reciprocal), lyc x arc, lyc x chm, lyc x che (reciprocal)... and do plan on crossing those with the above also. It could be nice to bump up the seed and fruit size that way whilst still having only 25% or even much less lyc.
3) It could be worth using ph-2 and ph-3 homozygous lyc to cross into these, since even with such glorious diversity, it's not worth much if they don't have sufficient LB resistance. I am now growing such lyc for that purpose.
4) If there is an Andean landrace lyc that has sufficient LB resistance, that could be a nice way of gaining seed and some fruit size, whilst completely bypassing the double bottlenecked genepool of mainstream tomatoes. Though that might be more of an intellectual pleasure than anything else, if one is to end up with anyway such a small percentage of lyc, and the increased fruit size available from crossing with more modern tomatoes might outweigh such concerns. So perhaps a large fruited ph-2 and ph-3 homozygous lyc would end up being a better choice.

[William Schlegel]

I do think Lyc evolved from pimp. I also think I was defining pimp too narrowly. The two accessions I got from the gene bank had leaves more like lyc than what I had previously thought of as pimp.

To speculate a bit wildly. A lot of variation is possible in a species complex with a dozen species in it.

So how did lyc come to be? How did the variation in pimp come to be?

The answer could vary depending on the tomato accession. 

The variation in lyc you just mentioned in South America is intriguing.

[Justin Jardinier]

Ah yeah, that makes sense.

[William Schlegel]

That bit about Amazonian SLC diversity is quite interesting.

The diversity in tomatoes is enormous.

You've made tremendous crosses.

[Garrett Schantz]

Believe I mentioned the idea of crossing only wild species as well


Seems like it would be easier to just focus on unique tastes, SI and disease resistances rather than making groups of plants and working on making lines with large fruits or whatever else.


Plus people have already noticed the problem, where new accessions being moved over in large numbers, to Wildling or other groups, isn't always ideal and can have issues with some goals.



Glad to see that someone else thought of the same idea.


Orange Peach is interesting. Garden Peach and Wapsipinicon Peach, all have fuzzy skin.

If I remember correctly, they're originally from Peruvian varieties in the mountains.

That's different from Cocona, from similar regions and whatnot. Garden Peach can also apply to Cocona.


The fuzz, seems to be different than the gene responsible for Woolly Kate, and other "fuzzy tomatoes."

Two of those tomatoes, have a cream / white, to a yellow coloration to them.


I've also found them to be fairly disease resistant. One "originated" in 1890 or so. Yeah. Rather old.

Granted there are different "strains."


I'd have to get into older stuff that I saved. But there are reports of fuzzy skinned orange / yellow tomatoes in the mountains.


I've taken a guess, that with the disease resistances, "spicy / fruity" flavors, cream / yellowish skin, fuzzy skin and the disease resistances - that the Garden Peach could be crosses with Solanum habrochaites.

It's well known that bees will carry pollen, some distances and that Peruvian varieties tended to be exserted to some extent.


I'd assume that Garden Peach and things, were stabilized or messed around with a bit.

I also have no evidence to support the claims.



I will agree that looking into Lyco types from South America, could prove interesting.


One big negative, is that modern varieties are bred to have less diversity and be more uniform. South America was hit pretty hard with that.



Go 100 years back, and you'd probably find a ton of cool landraces.


Early domestication reports, and complaints mention that tomatoes outcrossed a lot.


Europeans really wanted uniformity.


Small villages and the like, probably have the most diversity.


Teosinte crossing into corn was seen as a good thing by Native Americans. I'd imagine that some South American tomatoes which had exsertion, occasionally took in Pimpinellifolium genes or other things.


I'm unsure if they'd see that as a good thing as well, or not. Hybrid vigor would probably be very nice - immediately and be absorbed into a landrace.

[Justin Jardinier]

Thanks William. 69 successful interspecial tomato crosses (of which I have processed the seeds) so far this year, 29 of which were with wild females, 14 of which were wild x wild. And many more crossed fruits ripening....

Seems like it would be easier to just focus on unique tastes, SI and disease resistances rather than making groups of plants and working on making lines with large fruits or whatever else.

For sure the fewer things one selects for, the easier it is. But still, fruit size is important for me. I would not want to finish up with fruits only the size of pimp or gal, they're tiny! And I don't mind some populations with cherry sized tomatoes but I'd for sure want some that are bigger.

Plus people have already noticed the problem, where new accessions being moved over in large numbers, to Wildling or other groups, isn't always ideal and can have issues with some goals.

Would you like to elaborate?

Orange Peach is interesting. Garden Peach and Wapsipinicon Peach, all have fuzzy skin.

Any reports on how it (or those other fuzzy ones) does with late blight?

One big negative, is that modern varieties are bred to have less diversity and be more uniform. South America was hit pretty hard with that.



Go 100 years back, and you'd probably find a ton of cool landraces.

I think there are still many out there, and also in genebanks.

I'd imagine that some South American tomatoes which had exsertion, occasionally took in Pimpinellifolium genes or other things.


I'm unsure if they'd see that as a good thing as well, or not. Hybrid vigor would probably be very nice - immediately and be absorbed into a landrace.

I would guess they would select against them, due to fruit size reduction. Though I would not be surprised if people and/or villages would grow multiple landraces, like they do with potatoes or in other places, rice etc. So I would guess that's where more of the crossing would be. But anyway there'd be a lot more diversity in their landraces as a whole, and should still be now even if not as much as before.

[Garrett Schantz]

Yeah, but it seems like they didn't select against Exserted traits, till some new farming practices made their way over.

A lot of varieties also went to different villages and sometimes replaced other ones.


Gene / seed banks probably started a bit too late, to have the best landraces.



Most seed banks also don't note certain odd qualities of fruits or Exserted traits and things. It's usually disease resistances and whatnot.



The only main issue with Wilding, is that as lines progress - people are looking for larger fruits.


Eventually, they'll end up with a line of larger fruited plants.


They'll also probably select for things that lack fertility issues.


This means that some relatives, may not be able to just cross over ad readily as before.

And, while it's possible to set aside a large group of Wilding plants and the like, to cross with new things, large fruits would need to be reselected for. Over and over again, as new things are added to the pool.


Any interesting flavors, would be gone. Fruits may all become very watery.

Or sour.



With keeping a population of smaller seeded / fruited Pimpinellifolium crosses, this could enable crosses with smaller seeded relatives.


Flavor could be gradually worked on.

Then you'd move that over to something like Wildling once you have a very interesting population.


Rather than increasing fruit size or focusing on taste / flavor, you'd just work on disease resistances, and working on making lines that can cross readily with even more species.



With Wildling, most people will immediately want to select back towards larger fruits, tastier fruits and whatnot.

Adding in some Pimpinellifolium or other things, these can mess with Exserted traits.



I don't think people do it on purpose. But more recent crosses have seemed like an immediate push or want for larger fruits and other things - immediately, resulting in a lot of backcrosses to restore wanted flavors and size.



It's not so much an issue at the moment.


But, I've noticed that some Habrochaites accessions or other species already in mixes, which have resistances or traits that others don't - or things that may seem redundant, they're being seen as a pain to add in just for one thing or whatever else.


If we focus on a line with smaller seeds / fruit and try making a stronger plant, more resistances to whatever.



People may feel less inclined to backcross things into oblivion.


I feel like a lot of earlier crosses of Habrochaites and things, a lot of genes were lost due to climates not favoring some accessions or species.

Some of that is being worked on now.



I do feel that a smaller fruited line, to compliment an eventual very exserted line of Wildling, would be of interest.


Every now and again, just cross that population, back into Wildling or have them growing some distance from each other.


I feel like labs selecting put singular genes and flagging those, doesn't show the entire picture of what gives a plant resistances.


If you look at older hybrids, which were backcrossed over and over again in order to be resistant, they're still around.


Most studies show that a disease or pest resistance, is usually made up of a chain of resistances.


That's also why I've been interested in Solanum pimpinellifolium, despite it being used somewhat heavily in breeding.


Older hybrids / heirlooms lasting longer than newer ones, isn't a good sign.

Modern plant breeding of finding specific genes in labs and deciding that's entirely what makes a plant resistant, and selecting for those genes in plants using markers.


A lot of other genes get lost.




Garden Peach and Wapsipinicon Peach, both seemed Late and Early Blight resistant when I grew them.

I wanted to see if they were the same varieties or not. They're somewhat different in flavor and fruit size.


I've read that they may not be as resistant to some newer strains of blight, or it depends on the year they're grown.