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Post by Tom Wagner on Sept 14, 2010 13:00:11 GMT -8
There is one area where I plant tomatoes every year. It is usually the first to come down with late blight and of course, I do not every spray for control. I think the blight is fully entrenched in the soil here and no effort is made to clean up the debris in any year.
It appears that Ph-2 and Ph-3 are still operative in controlling the outbreak.
Make My Day is one that has both the Ph-2 and Ph-3 gene in a homozygous pairing. No blight
Matt's Wild is homozygous for Ph-2. No blight.
The tomato hybrids that have Ph-2 from one parent have slight resistance to the foliage, but not as much control on the fruit as I would like.
Hybrids with Skykomish which is homozygous for Ph-2 and Ph-3 have slight resistance.
I will check the progress as the blight burns through. It started about three days ago.
With many, many hybrids of these lines being put away as F-2 seed, a fuller evaluation for 2011 will be to look for segregations that are true breeding for the best blight resistance/tolerance. Homozygous traits need to be found in every time of tomato, whether is a red, bi-color, green, striped, black, yellow, etc.
Tom Wagner
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Post by DarJones on Sept 15, 2010 16:54:22 GMT -8
Either found... or bred in.
DarJones
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Post by PatrickW on Sept 18, 2010 1:59:26 GMT -8
Before I left for my visit to you, most of my tomato plants were wiped out or seriously infected, but I kept one Tomatito de Jalapa that only showed a light infection. It's limped along until today, when the blight really set in. Have you grown this one? Until now, it's really the only one that's showed any meaningful resistance here. Next year I'll try the Skykomish, and see how it does here.
As far as potatoes, until now none have shown much signs of infection. Since a number of them are dying down from maturity anyway, it's hard to tell anymore if they have resistance.
Pam Wagner is completely untouched from blight. Sun Dude (does this have tall foliage?) is showing a lot of resistance, but is lightly infected. There may be others, I will go back later today or tomorrow and have a closer look. I was a little rushed today, and didn't have anything to write with. They are also growing close together, and at first glance I wasn't sure about a few varieties that might have some resistance.
None of the TPS showed any signs of resistance, but again I'll have a closer look.
Are there any varieties I should take a particularly close look at?
We're having a serious infestation of voles right now, and many of my fellow gardeners have reported when they tried to dig their potatoes all the tubers were missing. I haven't had a chance to dig any yet, but I'm a little concerned about this. Voles have all but decimated my Jerusalem Artichokes, so I can only assume my potatoes have faired as bad.
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Post by dkelly on Sept 19, 2010 21:05:45 GMT -8
Good to hear that the ph-2 ph-3 combo provides strong resistance. If there is a ph-2 and a ph-3 is there possibley a ph-1 or ph-4 ect..? I am just starting a batch with these genes, keep you notified on progress and resistance levels... will be innoculating with nasties for screening purposes. Is it theoretically possible to have a tomato with complete resistance to every nasty?... fulvia..alternia...septoria...tswv....tylcv...tomv...pmv..........? Also just tasted one of the UH varietals "kewalo" not so great tasting even worse texture... is the bacterial wilt tolerance say from this variey dominant? feel free to ignore my questions i'll figure it out someday  Thanks for providing a window to your work/mind. -dan |
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Post by Tom Wagner on Sept 20, 2010 19:03:59 GMT -8
I can answer a few questions only by linking to previous studies by others. The search for LB resistance has been going on for a long time and my guess is that it will continue for even a longer time. www.springerlink.com/content/x252574681760462/apsjournals.apsnet.org/doi/abs/10.1094/PDIS-93-9-0947?journalCode=pdisTherefore, there is no Ph-4 yet. There was some resistance in the past with Ph-0 and Ph-1 but not much is there today. Ph-3 is the same as 3707 as derived from pimpinellifolium. Since I am working with the Ph-2 and Ph-3 and getting some resistance in the hybrids but better resistance for each is they are homozygous. If you have read one of the quotes above, namely:< The data support the hypothesis that race-non-specific resistance in L3707 is controlled by two independent genes: a partially-dominant gene and a dominant epistatic gene> implies that there are two genes in operation with Ph-3. So it seems I have a lot of work to stabilize lines with those genes, since I do not know if they are linked somehow, or have marker genes, and or some other expression. All I know are based on results from variations of plant resistance. |
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Post by DarJones on Sept 20, 2010 21:23:22 GMT -8
There is a PH5 but you won't find it in the literature. To my knowledge, only one researcher is working with it and he refuses to share breeding stock. You can find a reference on the web to PH7 in a link from Florida.
Re Kewalo bacterial resistance, it works for the strain present in Hawaii but is not very effective against the strain here in the mainland U.S. If you happen to bump into seed for Hires Rootstock, it has decent tolerance to bacterial diseases, much better than Kewalo. I'm working on separating it out into a commercially viable tomato.
Re getting a single variety with tolerance to all of the diseases, so far it has not been possible. TOMV for example exibits very tight linkage which so far has prevented separating it into a viable breeding line. The problem is that there are two genes that have to be combined on the same chromosome but the linkage is so tight it has not yet been broken. The distance between the two critical areas is only a few hundred centimorgans.
DarJones
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Post by Tom Wagner on Sept 20, 2010 23:09:11 GMT -8
I did not know about the Ph-5 or 7. I tried to look up either on the searches and no luck.
I am not actively seeking new germplasm, trying to finish some of my pet projects and maintain a few old ones. Too many potato projects for my own good, too!
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Post by DarJones on Sept 21, 2010 21:43:32 GMT -8
Tom, search for "Foolad PH-5" and you will find the reference.
I forget where I found the PH-7 but think it was in an article out of Florida.
DarJones
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Post by dkelly on Sept 22, 2010 20:27:35 GMT -8
Thank you Tom and DarJones....as for ph-5 I enjoy a sporting hunt!
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Post by Tom Wagner on Sept 22, 2010 22:11:53 GMT -8
I put in a call to Majid earlier today but no reply yet. I was hoping to get more info before posting about the Ph-5 here, but this is all I have.... Majid R. Foolad, Professor of Plant Genetics 217 Tyson Building, University Park, PA 16802 2009 Tomato Fruit Quality Research Annual Report to PVMRP mrf5@psu.edu paveggies.org/m%20research%20report%2009%20foolad%20fruit%20quality.pdfI have no idea of how effective the resistance of this gene is. In other words...not enough data to make a comment. |
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Post by SUBHAMOY on Sept 6, 2011 3:07:51 GMT -8
I can answer a few questions only by linking to previous studies by others. The search for LB resistance has been going on for a long time and my guess is that it will continue for even a longer time. www.springerlink.com/content/x252574681760462/apsjournals.apsnet.org/doi/abs/10.1094/PDIS-93-9-0947?journalCode=pdisTherefore, there is no Ph-4 yet. There was some resistance in the past with Ph-0 and Ph-1 but not much is there today. Ph-3 is the same as 3707 as derived from pimpinellifolium. Since I am working with the Ph-2 and Ph-3 and getting some resistance in the hybrids but better resistance for each is they are homozygous. If you have read one of the quotes above, namely:< The data support the hypothesis that race-non-specific resistance in L3707 is controlled by two independent genes: a partially-dominant gene and a dominant epistatic gene> implies that there are two genes in operation with Ph-3. So it seems I have a lot of work to stabilize lines with those genes, since I do not know if they are linked somehow, or have marker genes, and or some other expression. All I know are based on results from variations of plant resistance. |
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Post by nicolas on Jan 26, 2015 2:22:12 GMT -8
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Post by DarJones on Jan 26, 2015 9:20:14 GMT -8
Nicolas, the article is primarily about ph2 and ph3 and has only brief mention of ph4 and ph5. They found that there is no single ph4 gene, rather it is multiple genes each with a small effect that gives the resistance. It is similar to ph-5 in this respect but ph5 has been isolated to 2 specific regions of DNA.
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Post by Tom Wagner on Jan 26, 2015 22:08:05 GMT -8
None of the wild species had complete resistance to late blight this past year just before frost..not even hirsutum (haborchaites) but my Magic Lineup must be inheriting other genes that give extra protection besides homozygous ph-2 and ph-3. Only one of 14 rootstock varieties had lasting resistance and I am taking that to the F-2 level for breeding. I am making clonal selections of F-2 rootstocks of all the kinds tested and making efforts to retain the wilder versions and the vigor of those are outstanding. I put those in 12 inch deep pots today in the greenhouse. I have the first blooms of tomatoes taunting me to make crosses now.
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