RL vs PL Origin of Tomato

[Pippin]

There was this earlier discussion related to an article of PL plants and Brix per yield. Those researchers tested some broad leaf plants classified as PL by amateurs (i.e. from Tatiana’s tomatobase). Not all PLs had the c gene (C = cut leaf, c = potato leaf). For example, Stupice was a true cc but Glacier was not. Don’t know what other options than c there might be for a broad leaf genes but at least tgc listed both c and e.

Unusually wide tomato leaflets are due to two recessive alleles, c and e. They are difficult to distinguish sometimes because the expression of e is indistinct in certain phenotypes. Usually the leaflets of ee broad-leaf tomato plants are wider than normal and the end leaflets are nearly entire with a few sharp pointed basal lobes.

The cc potato-leaf tomato plants have almost entire terminal leaflets with mostly, smooth margins. However, some end leaflets have halberd shape or 1 to 4 lobes. Plants with cc and ee have compound leaves. The Cc gene occurs in Chromosome 6, Linkage Group IV while the Ee gens occurs in Chromosome 4, Linkage Group XI.

https://tgc.ifas.ufl.edu/vol11/v11p28.html

[Pippin]

In the same tgc link, there seems to be an example where ”PL” segregated back to a RL: the G1668 X G2038 cross was PL in F1 but in F2 there were 2 RLs and 58 PLs.

https://tgc.ifas.ufl.edu/vol11/v11p28.html

[Toomanymatoes]

In the same tgc link, there seems to be an example where ”PL” segregated back to a RL: the G1668 X G2038 cross was PL in F1 but in F2 there were 2 RLs and 58 PLs.

https://tgc.ifas.ufl.edu/vol11/v11p28.html

Thats pretty interesting! I will have to read more about the e gene. Definitely could explain the leaf variation between PL plants.

In regards to the 2 RLs in the above study, the authors noted "*These 2 normal-appearing plants may be explained as natural crosses in the field with normal +-pollen from other plants.".

[JRinPA]

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

Yeah...about half of them are called "regular leaf".
Maybe less, about six from that pic that I would call potato leaf.

[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

Yeah...about half of them are called "regular leaf".
Maybe less, about six from that pic that I would call potato leaf.

Well, I think the purpose was to just look at plants with wide leaves. They sequenced 8 of the 18 varieties and found a mutation in the c gene for 7. So, you are correct and they most certainly are not all PL. Possibly the others have the recessive e gene. Interestingly, Pruden's Purple had a unique mutation.

[Tormahto]

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

Yeah...about half of them are called "regular leaf".
Maybe less, about six from that pic that I would call potato leaf.

Well, I think the purpose was to just look at plants with wide leaves. They sequenced 8 of the 18 varieties and found a mutation in the c gene for 7. So, you are correct and they most certainly are not all PL. Possibly the others have the recessive e gene. Interestingly, Pruden's Purple had a unique mutation.

In my amateur musings, Pruden's Purple IS a mutation.That is the variety that produced my one and only quadcot, double header plant (with different shaped fruit on opposing headers), in all of my years of gardening.

[ddsack]

While designating plants as PL or RL is useful for general description, it does not take into account that leaf form is on a long continuum from the skinny fern leafed Silvery Fir Tree types to fat smooth potato leafed. The line blurs when you find the mitten form PL's and very slightly serrated potato leaves. I don't have the knowledge or patience to figure out the genetic factors on degree of potato-leafness of these border line forms, but find it interesting on where the tipping point is decided.

I do not find that all the leaves on any one PL plant look exactly alike. So when I look at that picture chart of the various PL varieties, I can't say that showing just one leaf is necessarily representative. Just about all of those leaves might have been interchangeable between varieties, depending on location on the plant where the leaf was gathered, more slender forms growing near the top.

This has been a most enjoyable thread, especially the old American Breeders article.

[Shule]

In the same tgc link, there seems to be an example where ”PL” segregated back to a RL: the G1668 X G2038 cross was PL in F1 but in F2 there were 2 RLs and 58 PLs.

https://tgc.ifas.ufl.edu/vol11/v11p28.html

What happened there was probably cross-pollination, rather than a segregating back to a previous trait:

"These 2 normal-appearing plants may be explained as natural crosses in the field with normal +-pollen from other plants."

There were probably two grains of pollen that each fertilized a seed; the rest being untouched.

I do wonder if any of those PL-types might be dominant over the standard obvious RL; I've experienced some situations that make me wonder if a dominant PL might exist somewhere. I mean, I believe I've had a few unstable tomato growouts where the parent was RL and like 90% were PL. Statistically, it would seem you could normally probably only expect about 53% PL at the most (even with a lot of growouts), and 53% would be rare. One possible explanation is that the parent was heterozygous RL/PL, and it was cross-pollinated with a PL/PL tomato (even then, the odds of getting quite that many PLs are low).

[Pippin]

Here is a link to a picture of the ee (entire) mutant (that can be easily mixed with the PL cc) in the Micro-Tom background.

http://www.esalq.usp.br/tomato/entire.pdf

Interestingly, it is classified as a hormone mutant, rather than a leaf shape mutant. Apparently, ee has stronger response to auxin than the wild type.

http://www.esalq.usp.br/tomato/

[Cole_Robbie]

I have noticed when growing seedlings that rl varieties lock their leaves together much more efficiently. For a vining plant in a wild environment, being able to hold itself up and grow over competing plants would be an advantage.

Pl plants seem to suffer sunburn worse on the leaves as seedlings. But a larger leaf surface area overall should theoretically make more sugar and sweeter fruit, given the right conditions. And on that note, being tasty is an evolutionary advantage, too, in that it encourages animals to eat the fruit and spread the seeds.