RL vs PL Origin of Tomato

[greenthumbomaha]

To my memory, there was a discussion of tomato leaf shape with 25% PL and the majority RL (roughly 75% exclusive of wispy).

I'm looking at my growing tray for the Ukraine Tribute Grow Out. I have 23 varieties startied, with multiples of most (where will I put them??). Not all are specifically Ukrainian, but have some connection to the immediate region.

The seedlings are large enough to say definitively that ony three varieties are PL.

I'm wondering why this desparity in leaf selection... Is there special adaption to the shorter/colder growing season? Did the PL originate from this region and many crosses evolved? Just random goofiness in the seeds I picked from my huge collection?

I worked on a project with another MG gardener, and she came upon a fact that I was not aware of. Ukraine has "back gold" soil, and the upper midwest also has a swath of this growing utopia,

- Lisa

[Tormahto]

I have no idea about the origins of RL and PL varieties.

I do have an idea of why there are so many PL pink beefsteak varieties compared to the much rarer PL red beefsteak varieties. People have long saved seeds from the tastier tomatoes.

[bower]

PL is more rare than RL because the gene is recessive.
Where we find PL, it has been selected deliberately, more than likely. If you're selecting for another trait that's more important to you - taste for example - you'll always have about 3/4 plants which are RL in a PLxRL, so 3X the chances of your tastiest candidate being RL. That is unless you select for PL first of all, and then select for taste in the next generation. The PL could still turn up in later generations but again, the numbers are stacked against it, there will always be a greater chance of selecting away from that recessive allele, which doesn't show up in PL/RL plant.

[Doffer]

@Bower I disagree because tomatoes are self-pollinating. After about 7 generations, the plants are homozygous and without selection, just as many recessive traits as dominant traits will be visible among the various varieties.

So if you cross the P (parent) generation PL x RL, then after 7 generations of self-pollination, 50% PL and 50% RL plants will occur.

[Toomanymatoes]

@Bower I disagree because tomatoes are self-pollinating. After about 7 generations, the plants are homozygous and without selection, just as many recessive traits as dominant traits will be visible among the various varieties.

So if you cross the P (parent) generation PL x RL, then after 7 generations of self-pollination, 50% PL and 50% RL plants will occur.

Assuming RL and PL are derived from a single gene locus and follow Mendelian inheritance, if you cross a PL and RL, 50% of the offspring will be heterozygous RL. Those in turn, through self-pollination, will produce 75% RL and 25% PL as @Bower indicated. That will never change unless you select a homozygous variant and move forward with that. Easy enough if you want the PL, but the RL you select will have a higher chance of being heterozygous unless there is another way to know through another linked trait or incomplete dominance.

[Shule]

@greenthumbomaha

If you're talking about growing unstable tomatoes--

It's important to realize that tomatoes don't follow society's preferred method of defining 'random' or 'chance' when sorting out genes. It's more like rolling physical dice, where it's indeed possible to roll the same thing over and over again forever (even if it's not very likely). Society would have it where when generating a random number between 1 and 10, there's absolutely no chance for it to generate the same number a bunch of times in a row, even if you get lucky (and also they want it to guarantee that all of the numbers will show up when you do a certain number of generations; so, in essence, they want the order randomized, rather than the result, and that's not how tomatoes work, I believe).

So, it's perfectly normal to get only a few PL. It's even possible for all of them to be PL, or all to be RL. However, the odds are still 25% PL and 75% RL (50% heterozygous RL/PL; 25% homozygous RL/RL). The results don't always match the odds. A 25% chance of getting PL doesn't mean a fourth of the plants are always PL. It's a chance.

[Shule]

So, I just made a computer program that generates possible outcomes for this scenario (although I'm not sure the randomness in my program works quite like nature's assortment). Here are some results it produced, with 23 plants (assuming both parents are heterozygous RL/PL):

How many plants? 23
RL/RL: 7
RL/PL: 9
PL/PL: 7
RL: 16
PL: 7

How many plants? 23
RL/RL: 5
RL/PL: 9
PL/PL: 9
RL: 14
PL: 9

How many plants? 23
RL/RL: 5
RL/PL: 10
PL/PL: 8
RL: 15
PL: 8

How many plants? 23
RL/RL: 6
RL/PL: 10
PL/PL: 7
RL: 16
PL: 7

How many plants? 23
RL/RL: 5
RL/PL: 9
PL/PL: 9
RL: 14
PL: 9

How many plants? 23
RL/RL: 6
RL/PL: 12
PL/PL: 5
RL: 18
PL: 5

How many plants? 23
RL/RL: 7
RL/PL: 8
PL/PL: 8
RL: 15
PL: 8

How many plants? 23
RL/RL: 5
RL/PL: 11
PL/PL: 7
RL: 16
PL: 7

How many plants? 23
RL/RL: 8
RL/PL: 12
PL/PL: 3
RL: 20
PL: 3

How many plants? 23
RL/RL: 4
RL/PL: 9
PL/PL: 10
RL: 13
PL: 10

How many plants? 23
RL/RL: 5
RL/PL: 12
PL/PL: 6
RL: 17
PL: 6

How many plants? 23
RL/RL: 11
RL/PL: 5
PL/PL: 7
RL: 16
PL: 7

How many plants? 23
RL/RL: 6
RL/PL: 10
PL/PL: 7
RL: 16
PL: 7

How many plants? 23
RL/RL: 8
RL/PL: 13
PL/PL: 2
RL: 21
PL: 2

How many plants? 23
RL/RL: 8
RL/PL: 12
PL/PL: 3
RL: 20
PL: 3

How many plants? 23
RL/RL: 3
RL/PL: 12
PL/PL: 8
RL: 15
PL: 8

How many plants? 23
RL/RL: 4
RL/PL: 10
PL/PL: 9
RL: 14
PL: 9

How many plants? 23
RL/RL: 5
RL/PL: 12
PL/PL: 6
RL: 17
PL: 6

How many plants? 23
RL/RL: 3
RL/PL: 14
PL/PL: 6
RL: 17
PL: 6

How many plants? 23
RL/RL: 7
RL/PL: 12
PL/PL: 4
RL: 19
PL: 4

How many plants? 23
RL/RL: 4
RL/PL: 12
PL/PL: 7
RL: 16
PL: 7

How many plants? 23
RL/RL: 13
RL/PL: 7
PL/PL: 3
RL: 20
PL: 3

How many plants? 23
RL/RL: 8
RL/PL: 8
PL/PL: 7
RL: 16
PL: 7

How many plants? 23
RL/RL: 10
RL/PL: 9
PL/PL: 4
RL: 19
PL: 4

How many plants? 23
RL/RL: 5
RL/PL: 12
PL/PL: 6
RL: 17
PL: 6

How many plants? 23
RL/RL: 5
RL/PL: 15
PL/PL: 3
RL: 20
PL: 3

How many plants? 23
RL/RL: 5
RL/PL: 12
PL/PL: 6
RL: 17
PL: 6

How many plants? 23
RL/RL: 7
RL/PL: 9
PL/PL: 7
RL: 16
PL: 7

How many plants? 23
RL/RL: 5
RL/PL: 7
PL/PL: 11
RL: 12
PL: 11

How many plants? 23
RL/RL: 8
RL/PL: 12
PL/PL: 3
RL: 20
PL: 3

How many plants? 23
RL/RL: 6
RL/PL: 9
PL/PL: 8
RL: 15
PL: 8

How many plants? 23
RL/RL: 3
RL/PL: 14
PL/PL: 6
RL: 17
PL: 6

How many plants? 23
RL/RL: 6
RL/PL: 10
PL/PL: 7
RL: 16
PL: 7

How many plants? 23
RL/RL: 4
RL/PL: 13
PL/PL: 6
RL: 17
PL: 6

How many plants? 23
RL/RL: 8
RL/PL: 8
PL/PL: 7
RL: 16
PL: 7

How many plants? 23
RL/RL: 7
RL/PL: 14
PL/PL: 2
RL: 21
PL: 2

How many plants? 23
RL/RL: 9
RL/PL: 9
PL/PL: 5
RL: 18
PL: 5

How many plants? 23
RL/RL: 8
RL/PL: 12
PL/PL: 3
RL: 20
PL: 3

How many plants? 23
RL/RL: 4
RL/PL: 12
PL/PL: 7
RL: 16
PL: 7

How many plants? 23
RL/RL: 7
RL/PL: 14
PL/PL: 2
RL: 21
PL: 2

How many plants? 23
RL/RL: 5
RL/PL: 11
PL/PL: 7
RL: 16
PL: 7

How many plants? 23
RL/RL: 5
RL/PL: 15
PL/PL: 3
RL: 20
PL: 3

How many plants? 23
RL/RL: 4
RL/PL: 12
PL/PL: 7
RL: 16
PL: 7

How many plants? 23
RL/RL: 4
RL/PL: 11
PL/PL: 8
RL: 15
PL: 8

How many plants? 23
RL/RL: 1
RL/PL: 15
PL/PL: 7
RL: 16
PL: 7

How many plants? 23
RL/RL: 6
RL/PL: 14
PL/PL: 3
RL: 20
PL: 3

How many plants? 23
RL/RL: 6
RL/PL: 12
PL/PL: 5
RL: 18
PL: 5

How many plants? 23
RL/RL: 4
RL/PL: 12
PL/PL: 7
RL: 16
PL: 7

How many plants? 23
RL/RL: 5
RL/PL: 11
PL/PL: 7
RL: 16
PL: 7

How many plants? 23
RL/RL: 6
RL/PL: 13
PL/PL: 4
RL: 19
PL: 4

How many plants? 23
RL/RL: 12
RL/PL: 7
PL/PL: 4
RL: 19
PL: 4

How many plants? 23
RL/RL: 8
RL/PL: 10
PL/PL: 5
RL: 18
PL: 5

How many plants? 23
RL/RL: 3
RL/PL: 13
PL/PL: 7
RL: 16
PL: 7

How many plants? 23
RL/RL: 10
RL/PL: 13
PL/PL: 0
RL: 23
PL: 0

How many plants? 23
RL/RL: 7
RL/PL: 9
PL/PL: 7
RL: 16
PL: 7

How many plants? 23
RL/RL: 5
RL/PL: 11
PL/PL: 7
RL: 16
PL: 7

How many plants? 23
RL/RL: 6
RL/PL: 14
PL/PL: 3
RL: 20
PL: 3

How many plants? 23
RL/RL: 6
RL/PL: 10
PL/PL: 7
RL: 16
PL: 7

[Pippin]

I understood the original question was about stable tomato varieties originating from Ukraine or thereabout, like from the former Soviet Union countries. If they had selected more of PL leaf types on purpose e.g. for better cold tolerance or if PL originates from that region. It remained a bit unclear to me if the proportion of PLs to RLs was 3 to 23 or 20 to 23 in this grow out (as it sounded like there were more PLs than expected).

I don’t know if PL phenotype is more common in Eastern European countries than elsewhere but the observation is interesting and also I can name easily some early PL varieties from that region (like some famous Czech cultivars). The only Finnish heirloom tomato that I know is PL, very likely originating from former SU.

I don’t think there are confirmed statistics of how many stable PL varieties for each RL variety there are globally, the 25% to 75% division seems like a misunderstanding coming from the genetics. I would have expected that PLs are much more rare than 25% of all tomato varieties.

I don’t think the PL gene originates from that region either. They likely just had access to a very wide gene pool. There were many massive seed banks and advanced plant breeding activities in former SU countries. Having more cold tolerant tomato varieties was likely one of the breeding goals but IDK if those efforts were related to PL gene.

[bower]

@Bower I disagree because tomatoes are self-pollinating. After about 7 generations, the plants are homozygous and without selection, just as many recessive traits as dominant traits will be visible among the various varieties.

So if you cross the P (parent) generation PL x RL, then after 7 generations of self-pollination, 50% PL and 50% RL plants will occur.

Yes, this could be correct in theory. It is the selection for another trait that makes the difference. Meaning to say, if you want a good taste, or disease resistance, or some other combination of traits, and you don't care what the leaf looks like, then it is more likely that you will include at least one RL allele in your selection because 3/4 plants have it, and over the course of stabilizing, end up losing the PL trait because it isn't visible in heterozygous plants.

I've read some recent work on PL genetics, and they found that many (if not all) of the heirloom/OP PL's are closely related. This suggests that PL may have arisen as a mutation in more recent times (say 400 years?), or perhaps it existed as a rare trait and was selected deliberately as a novelty by using that special PL parent in a cross to make a distinctive new tomato. This led to more crosses involving the new parent line and eventually over time, a diverse group of tomatoes with the PL trait, that could however be traced back to the same parentage using modern technology.

[Tormahto]

In my opinion, the 75/25 rule is valid for virtually all tomatoes. However, there may be a very tiny number of "varieties" that don't follow the rules. Many years ago, Carolyn mentioned one such tomato, which I currently can't recall, that consistently flipped back and forth between RL and PL with no apparent stability.

In my own tomato trials, I've seen that with one tomato. Some of the background is here...

http://www.tomatoville.com/showpost.php ... stcount=11

I started only 3 to 7 seeds each year, so the sample size was very small. However, in each year, every seed started was either PL or RL. There were no years when I had a mix of RL & PL seedlings. To me, those results were way outside of the 75/25 rule norm.

The one thing that I will correct is that those tomatoes do not taste like Stump of the World. 2003 most likely did not have the best weather conditions to bring out SOTW's best flavor. Since then, I now know what SOTW is capable of producing, flavorwise.

Now in the world of genetics, my understanding is that yellow-skinned reds are dominant over clear-skinned pinks. If so, in the PL realm, should there not be about 3 red varieties to every 1 pink variety if there were no biases in selecting for other traits?

However, the ratio of PL reds to PL pinks may be somewhere around 1 to 100, from an unscientific very rough estimate of mine. This coincides with my tastes, of tomatoes from my garden, where great tasting pinks outnumber great tasting reds by about that 100:1 ratio.

It's my speculation that way back when, people started saving PL pinks, at a higher rate than the natural output of leaf types and fruit colors, and that's why we're where we are today. My own garden coincides with a higher rate of PLs because of the flavors found in PL pinks.

[Pippin]

This PLflip-RLflop behavior is totally new to me, interesting… Makes me wonder if this would explain some off types from last season that I rejected after seeing the leaf types. I thought there was some inpurity in my seed source, might have been Cherokee Purple and Cherry Brandywine that I tested first time.

[Doffer]

@Bower I disagree because tomatoes are self-pollinating. After about 7 generations, the plants are homozygous and without selection, just as many recessive traits as dominant traits will be visible among the various varieties.

So if you cross the P (parent) generation PL x RL, then after 7 generations of self-pollination, 50% PL and 50% RL plants will occur.

Assuming RL and PL are derived from a single gene locus and follow Mendelian inheritance, if you cross a PL and RL, 50% of the offspring will be heterozygous RL. Those in turn, through self-pollination, will produce 75% RL and 25% PL as @Bower indicated. That will never change unless you select a homozygous variant and move forward with that. Easy enough if you want the PL, but the RL you select will have a higher chance of being heterozygous unless there is another way to know through another linked trait or incomplete dominance.

No, every generation the entire population will become more homozygous. Ultimately, there are so many homozygous plants that the heterozygous plants with PL/RL are negligible.
Below you can see that, for example, the F9 generation has 256 heterozygous plants against 65,536 plants. In this F9 generation there are therefore 50% RL plants and 50% PL plants.

1.png

[Toomanymatoes]

@Bower I disagree because tomatoes are self-pollinating. After about 7 generations, the plants are homozygous and without selection, just as many recessive traits as dominant traits will be visible among the various varieties.

So if you cross the P (parent) generation PL x RL, then after 7 generations of self-pollination, 50% PL and 50% RL plants will occur.

Assuming RL and PL are derived from a single gene locus and follow Mendelian inheritance, if you cross a PL and RL, 50% of the offspring will be heterozygous RL. Those in turn, through self-pollination, will produce 75% RL and 25% PL as @Bower indicated. That will never change unless you select a homozygous variant and move forward with that. Easy enough if you want the PL, but the RL you select will have a higher chance of being heterozygous unless there is another way to know through another linked trait or incomplete dominance.

No, every generation the entire population will become more homozygous. Ultimately, there are so many homozygous plants that the heterozygous plants with PL/RL are negligible.
Below you can see that, for example, the F9 generation has 256 heterozygous plants against 65,536 plants. In this F9 generation there are therefore 50% RL plants and 50% PL plants.

1.png

I was only referring to the heterozygous F1 and the heterozygous plants that follow. Not the entire population.

Sure, if you look at the full population starting at F2 over generations without any form of cross-pollination and constant numbers of offspring per genotype you will start to see more homozygous plants. Not surprising, considering homozygous only produce homozygous and the heterozygous produce both.

I get the same results as you with a simulation.

image.png

[bower]

I am really curious about the flipping thing. I've been growing "Oaxaca Jewel PL" for many years now. Everyone who hears that says "Oaxaca Jewel is RL". I thought maybe it was crossed with a PL somewhere at Solana Seeds where I got it. It is a strange variety because it got really noticeably earlier here every time I grew it out from my own seeds, and is now one of my super early and reliable tomatoes.
But one year the seed I saved was all RL. i had Northern Lights that year and we assumed that I mixed up the seeds (although I could hardly believe it). Fast forward this year, I started a half dozen of these for the farm, from seed in their stash. All RL. I assumed it was from that same batch of seeds that were mixed up with Northern Lights. Maybe it is. But the wierdest thing, these are the most vigorous seedlings of everything I sowed for the farm or for myself. They had 4 leaves when the others had 2. They really want to be potted up and should've been a week ago, they are way ahead of any others. I don't remember Northern Lights well enough, but sure don't remember them being so forward ahead of every other seedling.
So now I'm wondering if this could've been a flip...
I still have seeds from the Northern Lights, maybe I'll have to pit them against each other next year.

[Toomanymatoes]

I am not sure that 'flipping' from PL to RL is even possible. I imagine it is more likely to have been unknowingly crossed with a RL variety.

I am trying to determine ways that it could happen without crossing. One possibility is due to copy number variations of the c gene. Another is incomplete penetrance. I would still go with the more plausible explanation of crossing.

RL to PL I suppose is possible with a spontaneous mutation. I still think that would be a rare event.

Who knows though. Plant genetics are pretty crazy and definitely outside my realm.

[Shule]

From my research, it looks like the PL tomato trait was "of seedling origin" in 1870 or 1871.

The earliest PL varieties I know about by name are firstly Mikado (AKA Turner Hybrid), then a variety called Potato Leaf and also Ruby Queen. There was also a red version of Mikado that was potato leaf. Potato leaf varieties are said to have existed before Mikado, but I don't know if they were named. I don't know any other PL varieties from back then (I looked and didn't discover any), but there may have been more.

It should be noted that Brandywine back then was actually red and regular leaf (and was related to Trophy). So the PL trait didn't originate with Brandywine.

Pictures and description of Mikado from around back then let us know that it wasn't exactly like the Mikado of today. Drawings make it look floppy, just like Taiga (the wispy trait for PL tomatoes), and it has much larger fruit (like a wispy Brandywine or something). It wasn't an oxheart, if the drawings are correct.

Here are my sources that I have on hand:

- https://trueloveseeds.com/products/mikado-tomato
- Here's a picture of the fruit that someone drew of it from the 1800s
- Here's a drawn picture of Mikado's foliage. (I had the wrong link initially, but I fixed it.)
- Here's another one of the leaves (with an interesting description of varied tomato leaves across varieties.)
- This is also interesting. (Note that var. grandifolium refers to potato-leaf tomatoes.)

[Shule]

If you want to know how I find stuff like this, I usually use Google Books advanced search, check 'full view only' (and sometimes add a date range), and then search.

Note that the vast majority of items that appear when you check 'full view only' will be public domain (so, from a really long time ago--but that's helpful in narrowing down the results when searching for tomato history).

[Toomanymatoes]

Even the shape of the Potato Leaf seems to vary somewhat between the PL varieties.

PL_Varieties-Rowlandetal2020-001.jpg

from - https://nph.onlinelibrary.wiley.com/doi ... /nph.16403

[Toomanymatoes]

I was reading a paper from 1901 that describes a tomato "Potato-leaf Honor Bright" of Livingston. It seems like the PL variety had been known to gardeners at that time.

[Toomanymatoes]

Not to keep de-railing the thread (sorry), but I found this article regarding the origin of some of the Livingston varieties to be interesting. Looks like several of the Livingstone PL varieties were derived from a parental cross of "Potato Leaf" and Dwarf Champion = Fordhook Fancy. You have to love science from the past - "I did it because I felt like it."

https://books.google.ca/books?id=xX1NAA ... ht&f=false

American_Breeders_Magazine-PL-001.jpg

American_Breeders_Magazine-PL-002.jpg

American_Breeders_Magazine-PL-003.jpg