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Post by kctomato on Feb 28, 2009 11:33:31 GMT -5
Phillipine #2 (or Fillipine 2) is reported to have late blight resistance but I do not know which gene
I doubt you are interested but via GMO they have been successful at transferring the resistance genes from grapes into tomato.
When Dr Gardner and Dr Shoemaker trailed various varieties (including heirlooms) that were anecdotally noted for late blight resistance few held up to replicated trails. The ones that did ok would probably be reported in Brusca's paper. The only lines I saw with resistance when i was there were L hirstumum lines. A few lines like West Virginia 63 did slightly better than others on a reduced spray schedule.
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Post by PatrickW on Feb 28, 2009 13:07:11 GMT -5
Kctomato, what I see from reading Brusca's paper is the research was done by finding the Ph-1, Ph-2 and Ph-3 genes in different lines and combining them by creating a new line. In my opinion, what we are doing here is something a little different. We have one tomato already that has high LB resistance, contained in one or more unidentified genes, and the goal is to move this resistance into a more common tomato.
Also, since LB resistance seems to be very localized (Legend shows resistance in parts of the US, but not here for example), I wonder if these three genes identified really apply in our climate.
As well as thinking about blight resistance when I asked the question of good tomatoes to use for crossing, I was also thinking of what might taste good, produce attractive fruits or make for a productive plant when crossed with a wild tomato. I notice this was something Brusca said needed further research.
Anyone have any ideas on what might taste good or otherwise create a desirable variety when crossed with a wild tomato?
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Post by kctomato on Feb 28, 2009 15:01:33 GMT -5
Also, since LB resistance seems to be very localized (Legend shows resistance in parts of the US, but not here for example), I wonder if these three genes identified really apply in our climate. It's localized because there are different races of the late blight fungus. I suspect getting into the research farther might tell one if the various races are more or less resistant to which gene(s). I know they exist I have just never had a reason to keep up with the research. They are different due to mating types, resistance to a certain chemical, DNA fingerprinting and a few other techniques (new since I was around it). There are numerous races in the US alone. It's likely the source line of interest to you might contain one of those 3 genes or some other QTL (quantitative trait loci = many genes conferring resistance). Combining it with the other sources should help target more races and theoretically more adaptability to late blight resistance. That's why I suggested known sources. I would set up a plan to try to incorporate these genes into several backgrounds with good flavor (like an heirloom type) and either select from there or then start crossing those developed lines to each other to load up on resistant and a variation of fruit quality backgrounds. This is what it might look like - cross the resistant line(s) to several lines with desirable fruit qaulities
- start a backcross program to attempt to fix those genes in a homozygous state within each individual line of interest
now you may have something decent at that point depending on the parents used (red and blue paths to right and left) - once you have several lines with the mixed parent background and homozygous resistance start crossing those. These lines will be resistant in the F1 and segregating generations due to the homozygousity (purple path). At this point one can focus on combining those lines each with each other or backcrossing into the original flavor parents to select for the flavor qualities and then screen those.
It can get more involved such as starting a population of single seed descent lines off the resistant backcrosses and selecting from the best of those once stable. Such an effort takes considerable resources and time. (not represented below) Here is a visual representation for suggesting several methods that might be done R=Resistant line P=flavor parent RA= resistant line A RB= resistant line B etc I'd breed for your area. So pick a flavorful type that does well in your area. Essentially the idea is to load up on the resistant genes and get them homogenized and incorporate hopefully some flavor qualities in the process. If not, once homogenized for resistance, start adding the flavor back in and roll the dice.
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Post by pugs on Feb 28, 2009 19:09:24 GMT -5
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Post by michaeljohnson on Mar 14, 2009 0:24:11 GMT -5
There are lots of F1 hybrid tomatoes available today of good size tomatoes, that are very good late blight resistant, there are at least four or five that I can think of available now from UK seed merchants, Suttons seeds-Fantasia, Ferline F1, and several others also. But the real masters of the blight resistant varieties are the Russians-having many varieties available that are more or less totally resistant to late blight, Andrey Baranovski-from Belarus, a well know seed collector with whom I exchange seeds on a regular basis each year -has several in his collection that have been bred for late blight resistance. and are fairly easy to grow outside. For us in the UK and of course your area just across the water from us,. the time to watch out for each year is the last two weeks in July and the first two weeks in August when blight is likely to strike, at this time it is better to keep watering to a reduced amount and a bit on the dry side until the danger has passed, a blight seems to thrive in damp humid conditions- also it may help to give a spray with a copper based fungicide such as Bordoux mixture in mid July and again in early August-this usually holds it at bay until the danger has passed by late August.
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Post by PatrickW on Mar 14, 2009 5:10:44 GMT -5
Michael,
Finding tomatoes that claim blight resistance is no problem, there are lots of those around. As far as I'm aware however, there are no large sized tomatoes that have any real resistance. Frank has tried a number of Andrey's tomatoes, and so far hasn't found any that are really blight resistant. I'm also trying a few others this year. Note that I'm particularly interested in tomatoes that can grow outside, and without the use of fungicides like Bordeaux mixture.
One of the problems in assessing blight resistance is it tends to vary from year to year, even garden to garden. One year the weather can be good, and blight not be a problem, and the next year it can kill your plants before they even set fruit.
Another problem I have, and Frank as well, is there are laws in this part of Europe that oblige you to destroy infected plants. Especially since I grow tomatoes in a community garden, the moment my plants show even the slightest hint of blight there will be someone standing next to my garden insisting I remove them right away. I'm interested in breeding a tomato that is really completely blight resistant, not just one that shows some resistance.
If you or anyone you know has any personal experience with any specific varieties, F1 or OP, from Andrey or anywhere else, that show real resistance, preferably over more than one year, I'd like to hear more about what you've seen.
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Post by imgrimmer on Dec 27, 2012 15:59:59 GMT -5
What happened to this project? Is there an outcome? I Would be really interessted in to hear about. I try to select my best late blight tolerant plants since 3 years out of a mass cross with some progress, but maybe it is only luck and late blight will hit me next season, canĀ“t tell. So please let us know!
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Post by DarJones on Dec 27, 2012 20:02:31 GMT -5
There are 3 genes currently available that convey resistance to late blight. They are ph, ph2, and ph3. All three can be obtained with a bit of perserverance. New Yorker was one named variety with ph. It can be found in TGRC as LA2009. I have seed. Matt's Wild Cherry carries ph2 and is available from Johnny's. It is more difficult to find ph3 though I have it in at least 3 different breeding lines. LA1269 from TGRC supposedly contains ph3. LA2533 and LA2093 may also contain ph3 and/or ph2.
I have some breeding stock that makes fruit about 2.5 to 3 inches diameter and segregates 1:2:1 for ph3.
Better sources of resistance may be available in a few years as genes are introgressed from S. Habrochaites.
DarJones
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