Breeding for Late Blight Resistant Tomatoes

[Roland]

I grow Austrian Mountain Cherry (AMC) in 2023 near Primabella.

The resistance was just as strong as Primabella's. (so very good)
The color of the leaves is dark green like Primabella and the fruit size is approximately the same as Primabella.
I wonder if this isn't the same breed?

[Justin Jardinier]

Wow that's really interesting, thanks! I read that Primabella was bred in 2017? And that if it's true that AMC has been around at least since 1920, it must be different right?

Do you know if AMC has been tested for PH genes? I would assume that if it really is such an old tomato, then it has a good chance of not having the PH genes, in which case it could be extremely useful. I really value PH-2 and PH-3, but I think it could be very useful to additionally work on lines that exclude those genes, for when LB strains overcome them.

[Roland]

What i understooth is that Lukas' family has been successfully growing tomatoes outdoors in the wet Austrian climate since 1920.
Lukas found a paper bag of tomato seeds in a drawer of his deceased aunt with the label 2001. These tomatoes turned out to be very resistant and he named them AMC (Austrian Mountain Cherry).

[Roland]

Primabella was bred by Dr. Bernd Horneburg by inbreeding the Philovita F1 variety (heterozygous ph3). Cross-pollination most likely took place in the field with a red unknown tomato (Source Dr. Bernd Horneburg) from which Primabella emerged.

As far as I know, Primabella is the most resistant variety to late blight.

Primabella was introduced in 2013.

[Justin Jardinier]

So, since from the history it seems they are not the same breed, are you thinking that Primabella might be a cross of Philovita and AMC? And if Philovita has only PH-3, but Primabella PH-2+3, then if that really is the origin, AMC would have PH-2? (With also presumably some additional resistance).

It would be great is AMC were tested. If it has no PH-2 nor PH-3, it would seem especially valuable. But even if it has only 1 PH gene, performing as well as the best PH-2+3 resistance would indicate some very strong non-PH resistance.

[Roland]

The Resi variety is widely used by Dr. Bernd Horneburg because of its good field resistance. This would be ph2 homozygous.
Resi comes from a hobby gardener who did not know the name of the variety (like AMC), which is why this variety was named Resi.

I already have Resi seeds, but I have not grown or tested this variety.

Resibella and Rondobella come from the crossing Phantasia F1 x Resi. And are ph2+ph3 homozygous.
Resibella and Rondobella show good resistance here.

[Justin Jardinier]

In case anyone did not see this one:
Exploration of wild relatives of tomato for enhanced stress tolerance - Junming Li - 2010
https://edepot.wur.nl/50984

They test various introgressions lines from habrochaites LA1777

[Tim DH]

I grew Resibella once and was underwhelmed by its flavour. It also sprouted a forest of shoots along the main leaf ribs!

[ThomatoGarden]

Resi and Resibella have some Resistance to LB but they are much more
 subsceptible to cracking than Primabella or MM.

[Justin Jardinier]

Late blight tomatoes with Ph-2, Ph-3 and Ph-5 combined, have been made. Lecture here which briefly mentions this work, College Connections EP06 23: From Breeding to Treating, Disease Controls for Tomatoes:
https://youtu.be/U-kp2_6Grn0?si=Xjkyr45G-UFN860w

Description:

Tomatoes are the most popular vegetable in Pennsylvania, the U.S., and the world. But plant diseases can take your crop before you do. Dean Rick Roush is joined by Majid Foolad, professor of plant genetics; Beth Gugino, assistant dean for graduate education; and Kevin Hockett, assistant professor of microbial ecology, to discuss conventional and modern breeding techniques, microbial disease management, and applied research in the field to keep your tomatoes healthy and delicious.

[Roland]

So ph5-2 and ph2 are not a different allel on the same gene?

[William Schlegel]

10:16 minutes in. Cheerleading the shift to GMO tomatoes. I disagree of course. Why with the rich genetic resources in tomato wild relatives would we ever create GMO's? We certainly don't need to. Rationale appears to be corporate profits since it makes breeding easier and cheaper.

[Justin Jardinier]

So ph5-2 and ph2 are not a different allel on the same gene?

I didn't understand the graphic on that one. So I did not understand if it was or not. Did anyone get which it was?

[William Schlegel]

https://www.psu.edu/news/research/story/coming-garden-near-you-award-winning-penn-state-bred-tomato-variety/

More background on Valentine F1 and hints about what else may be coming or already available from Penn State collaborations.

https://www.johnnyseeds.com/vegetables/tomatoes/grape-tomatoes/valentine-organic-f1-tomato-seed-3371G.html

"This vivid red, high-yielding, and early blight-resistant tomato is the first commercial variety developed with Penn State's patented high-lycopene breeding lines. Excellent color contrast when mixed with Nova or Golden Sweet, Valentine adds diversity to a small tomato mix. Avg. fruit weight 12–14 gm. Long shelf life. AAS winner. US Patent #8,524,992. Indeterminate. NOTE: For best flavor, harvest when fruits are deep red. USDA Certified Organic." - Johnny's description.

https://patents.google.com/patent/US8524992B2/en

"2029-03-17
Anticipated expiration" - above patent page. It would be difficult to develop a stable high lycopene tomato from Valentine F1 before March 17 2029. It could be done with speed breeding but releasing it before this date would violate this patent. Still since this patent expires so soon, this is a trait that could be used for breeding right?!

https://etda.libraries.psu.edu/files/final_submissions/20711

"Ph-3 is the most
effective resistance gene against LB, and it is currently present in several commercial varieties.
Further, resistance to LB is more effective when Ph-3 is combined with Ph-2. A relatively new
LB resistance gene, Ph-5, has been discovered in the tomato breeding program at Penn State, but
has yet to be commercialized in any varieties. Ph-5 was determined to confer as much LB
resistance as Ph-2/Ph-3 combined. At Penn State, many processing and FM tomato lines have
been developed with LB resistance, and many experimental hybrids containing Ph-5, Ph-5/Ph-2,
Ph-5/Ph-3, and Ph-5/Ph-3/Ph-2 have been developed. " - Jonathan Thomas Bonfiglio thesis above link

"In 2013, the Penn State tomato breeding program produced and evaluated more than 300
large type FM hybrids. Hybrids were developed from high-lycopene lines combined with lines
containing early blight (EB) resistance. Beginning in 2017, newly developed Ph-5 lines were
used in crosses for experimental hybrids containing high-lycopene, EB resistance, and LB
resistance with one, few, or several LB resistance genes. Several hybrids evaluated in this thesis
project are more recently produced in 2018 along with nine other elite 2016 experimental hybrids. " - Jonathan Thomas Bonfiglio thesis above link

Seems from this that it's all hybrids being developed, so hard to say if the PH5 traits can be combined in a homozygous way or not. Sounds like it has a high potential to be offered with this patented high-lycopene trait.

[Justin Jardinier]

https://www.psu.edu/news/research/story/coming-garden-near-you-award-winning-penn-state-bred-tomato-variety/

Wow this part sounds really exciting, and really sad!

To find tomatoes with desirable characteristics, Foolad tapped gene banks at the U.S. Department of Agriculture and other research organizations for germplasm from wild varieties, then crossed them with cultivated varieties in an effort to incorporate those traits into new inbred lines and hybrids.

Foolad found one "accession," or genetic line, that had four to five times more lycopene — a powerful antioxidant that gives tomatoes their deep-red color — than cultivated varieties.

"That accession also showed some disease-resistance traits, so I started to focus heavily on that one," he said. "We identified genes that controlled high fruit lycopene content, and we were able to characterize and patent that trait."

Doesn't it sound a bit insane to find a trait, especially in a public gene bank, and then patent it? And, isn't that kind of contrary to the whole ethos of universities? Or like, is this a privately funded university? (Which would still sound immoral to me anyway- in my mind universities should be for the benefit society, not capitalism, though maybe I should not be surprised with all the publicly funded medical research in universities that end up with privatised profits via patents).

Or am I being unfair? I just now read actually on Johnny's Seeds:

Five percent of the royalties on sales of Valentine will support the public breeding program run by Dr. Foolad at Penn State University.

Maybe that's fair enough. What do you all think about that? I tend to be anti-patent but I guess it it's only a small cut and it goes straight back into the breeding program, that sounds maybe fair. No, actually on reconsideration, that to me sounds very fair in terms of using their material, but not in terms of owning an actual trait that exists in nature. I can't think of a way that could be moral.

Well anyway, on that topic, are there varieties or good accessions out there aside from Valentine F1 with such significant lycopene increase? And, would there be any particular issue of us breeding with them? (I guess not outside of the US at least). And, since "Valentine can have have twice the lycopene content of other grape tomatoes", I wonder if that is because it's heterozygous for that trait to try to stop people getting it? Or, if the decrease (from 4~5x) is associated with size increase, if it was a pimp or cerasiforme they originally got the gene from?

I'm also curious - I've noticed that crossing red lycopersicum with galagense give vibrant deep orange in the F1. I'm hoping to get nice such colour in the F2 also -perhaps it is more of a health benefit than the minimal amount of anthocyanin in the thin skin of black tomatoes? I don't understand how that works exactly, but I heard "The wild type allele B from wild species such as S. pennellii, S. cheesmaniae (and the sibling species S. galapagense) and S. habrochaites converts most fruit lycopene into beta-carotene." So, if the parent were one such tomato with huge lycopene increase, will that mean some of the F2 might therefore give similar beta-carotene increase compared to if the parent were a regular red lycopersicum?

I happened to take this photo yesterday, sorry for the one wrinkled tomato that's a bit old!

Left 2, lycopersicum; middle 4, galapagense cross; next 3, cheesmaniae cross; far right 2, chmielewskii cross. All interspecific crosses are 50% red lycopersicum. And, the galapagense crosses might appear slightly more red in this photo than in reality since my lights were turned down low to save my eyes while working, which makes them a bit more red than usual.