Blight Resistance in Tomatoes

[PatrickW]

Tom (or any one else who may know):

Between Emma Cooper and I, you gave us seeds from the following tomatoes:

2, 3, 4, 6, 9, 10, 11, 19, 20, 26, 29, 31, 32, 35, 40, 41, 43, 45, 47, 48 and two surprises: ? and ?.

Can you please tell me which lines have any hope of late blight resistance? I would still like to get these into the garden this year. I'm sure they would all be very exciting to grow, but I don't have space for them all!

[DarJones]

Late blight resistance is a bit tricky.

There are about 30 odd strains of late blight commonly found in the U.S. There are, at present, only three genes in tomato that protect against late blight. One of them is mostly ineffective (PH1), One of them conveys resistance to a few strains (PH2), and one conveys resistance to most strains (PH3), but PH3 is not effective against strains that PH2 prevents and vice versa.

So to get a high level of late blight resistance, it is necessary to get both PH2 and PH3 into a single variety.

There may be a couple of other late blight resistance genes but they have not been described and used effectively so far. I say 'may be' because there is some highly resistant stock in TGRC that seems to be a different resistance mechanism to any of the above three.

DarJones

[Tom Wagner]

2, 3, 4, 6, 9, 10, 11, 19, 20, 26, 29, 31, 32, 35, 40, 41, 43, 45, 47, 48 and two surprises: ? and ?.

Can you please tell me which lines have any hope of late blight resistance?

My notes are scattered, and I am hopelessly behind in correspondence, seedling, transplanting, sending out seed, tubers and information. Working for the Census 2010 full time is taxing and doing anything in my own time is purely hit or miss.

Between the tomato seed shared by Emma Cooper and Patrick...I found at least two...there may be more....that carry some of the genes PH2 and/or PH3.

#9 is an F-1 of this female…F-1 {(F-2 Black Plum x Casady’s Folly) x Black Prince}

To this male…………………… F-1 [F-2 {(F-4{NC2cms35-10 x F-2 (Gamblers x F-4 Sweet ‘N Sour)} x WV700] x Blue

I wish I had the technology to put that in a pedigree chart…it would be easier to visualize

Anyway, this hybrid will segregate for a wide variety of things. The PH-2 gene of WV700 may or may be carried but is roughly a 50-50 chance it is there at all is again a 50-50- chance of exprssing itself. The main objective is to look for some blue plums in next years progeny. And the same size as plums.

#45 is an F-1 of F-4 Campari x Skykomish
Skykomish has PH2 and Ph3 on both alleles, therefore the hybrid has a fighting chance to be somewhat late blight resistant. Skykomish was the only plant (2008) that was growing profusely next to other tomatoes dead for weeks due to LB and was next to a hybrid that carried those two genes from one parent …but alas it was dead from the blight. The hope is that the blight resistance is enough to start with as a hybrid, but if not, the F-2 plants next year may have one or more that are homozygous for one or both.

Crossing #9 to #45 would be interesting and I notice that I have sown both a couple of weeks ago.....the objectives include getting a blue plum with bi-color red/yellow/orange flesh with dapples of red blushes on the bud end of the fruit. If enough generations of selfing, etc., could be done, perhaps the PH2 and 3 could be true breeding as it is in Skykomish. Skykomish is a bi-color.

I have many dozens of different hybrids of Skykomish this year, and I intend to backcross those to Skykomish. I recently negotiated to get additional places to plant tomatoes into greenhouses...makes it easier to hybridize. I also have hybrids to segregated lines of Mountain Magic and WV 700, too! Some of the hybrids of Skykomish and Mt. Magic are in segregating populations and have been selecting for full sized tomatoes expressing rin influence. In the greenhouse I want to make crosses of 100% rins of F-3 Mt. Magic to Skykomish. The gene rin is a ripening inhibitor for those who don't know. And again, for those who don't know, the hybrids of rin to normal produces a hybrid with with firmer, longer lasting fruits.

Interesting, Patrick, those other numbers have some interesting hybrids...for example Koralik crossed by Volkov.

Tom Wagner

[PatrickW]

Thanks Tom. What you describe here for #9 and #45 sounds really interesting. I'll grow at least these, and if I have space I might try for a few others.

[kctomato]

I wish I had the technology to put that in a pedigree chart…

If you have a computer with a basic word processor and a basic image program, you actually do.