Breeding for Late Blight Resistant Tomatoes

[Adrian]

The responsible of this project is not connected here and i'm not a participant.
They say that Without rin the peel is more thin.
https://www.les-tomos.fr/viewtopic.php?f=111&t=1915&start=180
Page 19 to 22 you can see differents types of peels and colors.
Some stats here
https://www.les-tomos.fr/viewtopic.php?p=96245#p96245

[William Schlegel]

I made this cross a very long time ago. It was a delayed take and very slow to ripen. MMM x purple zebra F1.

Hope there is a seed inside!!

[William Schlegel]

One interesting side project with late blight resistant tomatoes was growing out LA1033 Solanum habrochaites. I made one failed cross with it as the pollen parent. I picked half the berries last weekend and half today. The stems are dried on the first half. My plan is to let them sit awhile before opening in the hopes of some ripe seed. The shaded backyard bed they grew in has a very long season but the plants are slow to ripen. R18 essentially rejected these growing conditions. It looks to be about to bloom as fall frost approaches!

LA1033 has a multi gene resistance to late blight that briefly got the PH4 designation before it was reassigned to a single gene trait in a pimpinillifolium accession or some such. Mainstream breeders have little use for this because using it would be difficult.

I figure in a high enough percentage habrochaites cross you might just squeak through with such a multi gene trait intact.

That's why I planted a clump of R18 next to it. To hopefully start the back contamination process. Not this year but maybe one of these berries will have viable seed.

[William Schlegel]

I made this cross a very long time ago. It was a delayed take and very slow to ripen. MMM x purple zebra F1.

Hope there is a seed inside!!

There were 12!

[Nicolas]

Great news !

If i get it correctly, those 12 seeds ensure that there is more than 95% probability that one of those 12 plants contains both Ph2 and Ph3 (in heterozygous form)

If you got LB pressure, it can be selected the same year. If not, i'm not sure how you can be sure to capture ph2+Ph3 in the long term, much so if it is self-incompatible

[William Schlegel]

Great news !

If i get it correctly, those 12 seeds ensure that there is more than 95% probability that one of those 12 plants contains both Ph2 and Ph3 (in heterozygous form)

If you got LB pressure, it can be selected the same year. If not, i'm not sure how you can be sure to capture ph2+Ph3 in the long term, much so if it is self-incompatible

I think I'll just not worry about it. It is a 1 in 20 year event here roughly. I'll end up with tons of extra seed. Seed of tomato lasts up to 14 years. So I'll save some in case conditions worsen. I'll share some early generation seeds with folks who do have LB pressure. I'll select for stripes, potato leaves, blue skin, exsertion. Then I'll outcross to Galahad F1 and repeat.

[William Schlegel]

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

Hot Streak F1 another PH2 PH3 heterozygous tomato with good flavor for us to play with. Uh already sold out till January and I just heard about it.

[Nicolas]

This one is interesting in that it has nice color and stripes, and is big sized. Nice find, a good material to de-hybridize (or to cross with other LB resistant F1 before de-hybridization)

[William Schlegel]

It is from the same breeding program I think as Purple Zebra F1. Which means that they have multiple striped disease resistant stable lines to use as the hybrid parents of both. I suspect both parents must be striped to have fully expressed striped parents. Dehybridization of hot streak and purple zebra should give us a lot of insight even in the F2 as to what those parent lines must look like. I wonder if they would show any real surprises.

I have already crossed purple zebra with my Mission Mountain Morning line where I crossed Big Hill HX-9 with my Mission Mountain Sunrise line. I could outcross to Hot Streak without losing the striping. I could also cross to my exserted tiger line without losing the striping.

[Roland]

Do u guys know the late blight genes from tomato Blushingstar F1?
https://www.totallytomato.com/product/T00101/11

https://www.panamseed.com/plant_info.aspx?phid=062000001049474

[William Schlegel]

Interesting!

[Roland]

What is youre experiance whit Purple Zebra F1 and fruit cracking?

[William Schlegel]

My clump of purple zebra F1 were grown in an odd wood board sided bed at the house a bit shaded and tree root invaded. It is also filled with soil mix not real topsoil. Mostly peat I suppose. They produced what I would describe as large cherries with a pointed tip. No inclination towards cracking. Though I wonder what they would do in the sun in real soil?

[Roland]

Do u guys know the late blight genes from tomato Darkstar F1?

https://territorialseed.com/collections/tomato/products/darkstar?variant=41647595880622

Osborne ask the breeder and confirm DarkStar F1 is heterozygous for ph2 and ph3.
https://www.osborneseed.com/catalog/item-content/84897/darkstar-f1/pr_84897

[William Schlegel]

Seems like Carol Deppe's dream is getting easier all the time.