Breeding Multiple Resistances into OSSI Tomatoes

[William Schlegel]

I saw a neat post today on Facebook by Frogsleap Farms. They've crossed Dwarf Beauty King an OSSI dwarf with some resistant lines.

Frogsleap Farm
9h  ·
When we did molecular marker analysis on a new dwarf F2 a few months ago, we were lucky to find two F2 segregants with a typical dwarf rugose phenotype that were also stable (homozygous) for the markers associated with VFF resistance.  The dwarf parent in the cross was Dwarf Beauty King and the fruit on both elite F2 plants look like a dead ringer.  I tasted before extracting seed this morning and flavor was very good.  We also made crosses with these elite F2's and a couple of our SLS donor lines.  By this time next year we should have dwarf plants with fruit like this, with resistance to SLS, VFF and LB.  If we can get three generations a year, we could have this combo of disease resistance in dwarf hybrids in a couple years.

-Frogsleap Farms

My thought has often been to cross tomatoes from Frogsleap Farms with OSSI tomatoes but them making crosses with OSSI tomatoes is also great news since they use molecular markers to inform their breeding.

[AndrewB]

Wow! Very cool! A good example of how Open Source is supposed to work!!

[Steph S]

Very nice. 
Marker assisted breeding is a great asset for incorporating disease resistance.

[William Schlegel]

I was thinking about Tim's back crossing Latah project. If I want some of the resistances found in Purple Zebra F1 one way to accomplish this would be to do another back cross. Though I think I would take my MMM F2 x Purple Zebra F1 and grow it out to at least the F2 and select my favorite plant. Then back cross that to Purple Zebra. That would give a plant that perhaps looked like a striped Mission Mountain Sunrise but that would have a much better chance of having some resistances.

I don't think in general though that I can breed for too much resistance here without heavy disease pressure. I think for that, crosses need to go out to folks with heavy disease pressure in the F2 and be grown to stability in such a region. However, I think I can up my chances of lucking into some resistance by crossing with resistant tomatoes.

I do wonder though, how much those tests cost. Developing hybrids is a way to protect that investment.

One thought I have though is that I really do have more pre-breeding to do as well. Like I've been working towards sort of a base model and my ultimate goal for that base model would be something like a striped, bicolor, anthocyanin, dwarf, with potato leaves. With the crosses I made last year, I am heading in that direction but there are a few generations in between. However, a tomato like that with a 3/4 pedigree of Purple Zebra would be possible to create- just would require some large grow outs during F2 generations to stabilize some things. Maybe some sibling crosses. a half sibling cross between MMM x Purple Zebra F1 and MMM x Brad's Atomic Grape could be interesting. As could a half sibling cross between MMM x Purple Zebra F1 and MMM x Aztek F2. Which would cut down the Purple Zebra percentage but including Purple Zebra basically into the prebreeding project would mean a little bit of a heightened chance of some resistances. Then ultimately when all the traits desired were assembled, I could back cross to Purple Zebra F1 and get a tomato that was 5/8ths Purple Zebra. Do a huge F2 grow out, pick the favorite tomatoes, maybe do a sibling cross if something is missing. Then outcross to Purple Zebra again and a 13/16th's Purple Zebra would be the consequence. Then basically just grow that through seven generations to stability to a potato leaf dwarf.

[Roland]

What kind of resistances from Puple Zebra F1 do u want to breed? Remember Purple Zebra will be heterozygous for the resistances.

So try to find a homozygous variety for youre Backcross to resistances.

Maybe Mountaineer Pride is a nice variety for youre bakcross project?

[William Schlegel]

I guess I am not too picky about which resistances. I like the stripes on Purple Zebra F1. Though I am not sure if I won't also dehybridize it.

[William Schlegel]

https://www.johnnyseeds.com/vegetables/tomatoes/beefsteak-tomatoes/hot-streak-f1-tomato-seed-4760.html

I just saw this hybrid. No idea if it contains utility patents or anything else that could prohibit breeding with it. It doesn't say that the late blight resistance is strong. However, it has an impressive eight resistances from of course both inbred line parents so it would be heterozygous for many of them, and it is striped. It is also much larger than Purple Zebra F1. It claims outstanding flavor. I sent a form email to Johnny's asking about utility patents or anything else that could prohibit breeding but will have to see if they respond.

[Roland]

Hot-Streak F1 is heterozygous Ph-2 and Ph-3

[Justin Jardinier]

Hot-Streak F1 is heterozygous Ph-2 and Ph-3

Do you have any seeds of it? Like to trade? I'd need only very few.

[Justin Jardinier]

Maybe Mountaineer Pride is a nice variety for youre bakcross project?

That inspired me to look it up.I found someone saying:

resistance is very good here and is homozygous for ph2 and ph3. The growth is weak and the taste is bad.

And someone else chipping in listing these available via culinaris seeds, saying they are supposedly all ph-2 and ph-3 homozygous:
Vivagrande (red beefsteak)
Rondobella (red saladette)
Resibella (red cocktail)
Primabella (red cherry)
And saying:

primabella contains some alternative resistance in addition to ph-2 and ph-3. so it´s probably the variety with the highest overall late blight resistance available today.

That Primabella sounded promising. Any thoughts on that?

[Tim DH]

Hi Justin,
I grew Primabella last year, at home and on the allotment. Last year we were (unusually) blight free, so I can't comment on that aspect. Personally I wouldn't class it as a cherry, I'd call it medium sized. The early taste was a bit sour but later fruit had a flavour my notes record as 'acceptable'.
Resibella, on the other hand was very heavy cropping, but had an unremarkable flavour. It's not (in my opinion) a cocktail. (Again I'd say medium) The leaves suffered very badly from sprouting forests of shoots. I'll not grow it again.
My favourite of that group (not on your list) was Sunviva. A yellow cherry with a good flavour.

[Roland]

Vivagrande does not have the ph2 gene.

Soon i have some F2 seeds from Hot streak. @ Justin, where u from?