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Post by jonnyyuma on Apr 9, 2010 20:53:54 GMT -5
[/quote]Seems to me that you are saying this:
Let's say I have 1000 f2 tomato plants. Among them I spot one exceptional plant (my dream plant). This technique allows me easily to "fix" it, i.e. in short time I will get homozygous diploid seeds that will produce plants with same phenotype as "my dream plant"! Did I understood correctly?[/quote]
The concept is correct. It probably won't work in practice though. The theoretical concept doesn't take in to account epistasis, pleiotropy, polygenic inheritance.
Jonny
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Post by nuts on Apr 10, 2010 3:42:46 GMT -5
The major source of improved production in plants today is via producing hybrids from highly selected inbreds. Conventional breeding requires years of work to find a viable inbred line that works. This development means a tremendous potential to produce highly inbred lines (doubled haploid) in a single plant generation. The potential is incredible from a breeding perspective. It means the ability to produce a full panoply of inbreds representing all possible combinations of the chromosomes in just one season. Doing this with conventional breeding would take 4 to 5 years under the best of conditions and require resources that only the largest companies could marshall. With this technique, even small breeders could develop high quality inbred lines with minimal investment. Once you have a library of high quality doubled haploids, you can perform a range of crosses to find the optimum heterosis. The Achilles heel of this is that it does not permit developing new traits. It only allows optimizing existing traits specifically for the purpose of producing hybrids. From a breeding perspective, there will always be a need to do conventional breeding followed by selection for improved performance. One further note should be made about this. As dna testing becomes more accessible and less expensive, it will become feasible to simply produce millions of seed and then test every single seed to see which have the desired combination. Taking tomato as an example, lets say you cross two desirable varieties producing an F1 and you then want to convert that F1 to an array of highly inbred plants representing the entire segregating genome from the F1. The tomato has 12 chromosomes so you would produce 531,441 seed which would then be grown out to find the 4096 doubled haploids. There is a way this could be done with far fewer seed if one used a decision tree and several generations of plants. I know it is raw mathematics, but it is fun. DarJones Hi fusionpower,there are you again,the infatigable advocate of monsanto. About mathematics,if you have 4096 haploids there are 4096^2 different combinations possible,that is more than sixteen million.But of course,with the new techniques that's very easy to screen,specially for the small breeders like me and you. Well,there is good news. Nature is producing millions of haploids,called pollen and ovules. And that's free.So,now the haploid technique is available for all.Without need for an expensive laboratory. I just hope this method won't be patented ;D ;D ;D Our heroes are folks like Tom Wagner,and not the techno freaks of monsanto. |
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Post by DarJones on Apr 10, 2010 9:03:16 GMT -5
Point missed nuts. I have no reason to plug for monsanto. I just don't like deliberately biased and incorrect views regardless of source. Monsanto is typical of any large corporation, motivated entirely by the bottom line. Tom Wagner happens to be an acquaintance and source of quite a bit of seed I am growing this year.
As for this method of producing doubled haploids, it is the first thing I have seen that has the potential to make potent breeding tools available to an average person. Consider what would happen if Tom could turn one of his potato populations into a doubled haploid and then cross two carefully picked lines. in two generations he could release a fully late blight resistant potato that would have both vertical and horizontal resistance and that would be stable and heritable.
Ask yourself how I got the number 531,441. For each chromosome, there are three possible conditions in each seed. Given a pair of chromosomes A and B, you could have AA, BB, or 2(AB). And I refuse to explain how it can be done, this is the technique that allows a plant breeder to go from 16 million combinations down to 531,441 which is an order of magnitude fewer plants to produce.
DarJones
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Post by Hristo on Apr 10, 2010 14:49:10 GMT -5
Well, I was afraid of that answer ;D. If they really mean that (actually I can't believe that they mean exactly this), then I'm stupid, because I do not understand how this is possible. My point of view: Lets say we have crossed Yellow Pear tomato with Black Brandywine. In f2 there will be unimaginable mix-up of phenotypes, all of them very heterozygous (Some time ago I made YP x Black Cherry, in f2 there were yellow, orange, pink, red, green and "black" fruits, and that is only one trait - fruit color). Then among them I spot one plant that meets my goals. Even if I produce infinite number of different haploid combinations all of them will consist of only 1/2 of the alleles present in the source plant (my dream plant). I can't imagine how by doubling (i.e. mirroring) only half of the alleles form my dream plant I will end up with same combination of allele pairs. That is not possible. The resulting plant will be completely different from my "dream plant". Am I wrong? Also, they say: "should work in any plant", sorry, but I can't understand how this will work with plants that have separate sexes, i.e. male plants which have XY chromosome pair???!!!  It probably won't work in practice though. The theoretical concept doesn't take in to account epistasis, pleiotropy, polygenic inheritance. This is so obvious, that is why I think that here WE misinterpreted what they mean. What Hristo does not know is that 2 years ago I got a few seeds of these, coming from Russia through a french friend, and it turned out every plant was producing a different potato, although all with white flesh. »Some looking like russets, oblong, some rounds, but no russeting whatsoever, all either largely or slightly different, certainly not ''true to type''. All of them great to eat though....almost 50% as good as Tom Wagners potatoes from true seeds... That is why I called them "(nearly) homozygous" even the seed company calls them "variety-population". Probably they are f4 or f5. It's good that they taste good, but can you tell me which variety(ies) you tried? There are more than 10 different varieties and not all of them are described as having excellent taste. |
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Post by canadamike on Apr 10, 2010 15:46:37 GMT -5
I got a few seeds of FERMER and IMPERATRIZA those you sent me. There was more variability in shapes, from round to oblong with Imperatriza.
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Post by Hristo on Apr 10, 2010 15:55:37 GMT -5
Yes, according to their descriptions they should be among the better tasting ones. These seeds may be newer, i.e. further f's, but for sure still will be some variability.
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Post by nuts on Apr 10, 2010 16:51:55 GMT -5
Point missed nuts. I have no reason to plug for monsanto. I just don't like deliberately biased and incorrect views regardless of source. Monsanto is typical of any large corporation, motivated entirely by the bottom line. Tom Wagner happens to be an acquaintance and source of quite a bit of seed I am growing this year. As for this method of producing doubled haploids, it is the first thing I have seen that has the potential to make potent breeding tools available to an average person. Consider what would happen if Tom could turn one of his potato populations into a doubled haploid and then cross two carefully picked lines. in two generations he could release a fully late blight resistant potato that would have both vertical and horizontal resistance and that would be stable and heritable. Ask yourself how I got the number 531,441. For each chromosome, there are three possible conditions in each seed. Given a pair of chromosomes A and B, you could have AA, BB, or 2(AB). And I refuse to explain how it can be done, this is the technique that allows a plant breeder to go from 16 million combinations down to 531,441 which is an order of magnitude fewer plants to produce. DarJones fusionpower, I understand, AB is the same as BA because both sets of chromosomes are from the same parent.Thanks for explaining.So you get 3^12=531,441 combinations.This is the same number you get by selfpollinating. (Hope I didn't miss something again). I think Tom would just do a selfpollination and he would forget about the doubled haploids in the fridge But I can be totally wrong,maybe he will understand how to create a horizontal and vertical blight resistant potatoe in just two generations by doubling a haploid.I don't And no one in this thread has explained how this miracle is possible. |
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Post by kctomato on Apr 10, 2010 17:49:46 GMT -5
But I can be totally wrong,maybe he will understand how to create a horizontal and vertical blight resistant potatoe in just two generations by doubling a haploid.I don't And no one in this thread has explained how this miracle is possible. the short answer is you are fixing the genes in a shorter amount of time if you don't understand the reason for that, I suggest going to this place that still exists called a library. They have these things called books that still go way beyond what one can find on the internet. There people of authority had the time to painstakingly detail the information you seek. yes the places generally smell a little musty but what you find there can be intriguing. In particular I like the sexually repressed looking librarians who are always helpful when you are seeking to look up something. |
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Post by nuts on Apr 11, 2010 2:50:36 GMT -5
But I can be totally wrong,maybe he will understand how to create a horizontal and vertical blight resistant potatoe in just two generations by doubling a haploid.I don't And no one in this thread has explained how this miracle is possible. the short answer is you are fixing the genes in a shorter amount of time if you don't understand the reason for that, I suggest going to this place that still exists called a library. They have these things called books that still go way beyond what one can find on the internet. There people of authority had the time to painstakingly detail the information you seek. yes the places generally smell a little musty but what you find there can be intriguing. In particular I like the sexually repressed looking librarians who are always helpful when you are seeking to look up something. [/center] [/quote] This is the best argument I heard "there people of authority hadf the time to painstakingly detail the information you seek" who would dare to argue with people of authority? But this way discussion becomes useless. Maybe you could share some of the information you obtained? Isn't the discussionboard for that? |
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Post by DarJones on Apr 11, 2010 7:24:43 GMT -5
What makes you think it is worth Mule's time to educate you? That is your job and your problem. Mule is a plant breeder with an education in plant breeding and tomatoes specifically. Jonnyyuma is also a plant breeder with a background in plant breeding and melons in particular. Each of them paid the price of getting an education. I grow and sell tomato and pepper plants. Would you care to guess how many calls I get from people who want to know how to produce tomato and pepper plants in their own greenhouse? So far, I've given them good information to the best of my ability but it is frustrating. I paid the price of learning how to do the job. Why should I take my hard earned knowledge and give it away to someone who won't understand. They will not have had the experience of losing 5000 plants in one night because the heat failed and the greenhouse got too cold. Lesson learned - have a backup heat source and a temperature alarm in the greenhouse.
DarJones
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Post by mnjrutherford on Apr 11, 2010 9:38:25 GMT -5
You really make some good points about the educational aspect of the issues Dar. I hope you don't mind if I put forth an additional conjecture for consideration?
I am a high school drop out. Interestingly, some people are shocked to discover this, but most are not. Regardless, there is so much to learn and very little time in a life and schools of the traditional "brand" do not make themselves available to all comers. Nor are all people who desire to learn capable of assimilating the way things are taught in the standard setting.
Over the years, I have developed the belief that knowledge is best used when it is shared. Acquisition of knowledge always has a cost, but that cost is not always "coin of the realm" so to speak.
I've been trying very hard to follow this particular thread. It's been fascinating. But sadly, when you speak of haploids, diploids, YP x RB with or without the XY chromosome, you are so far beyond me it's pathetic. I am the village idiot compared to you. Yet, thanks to your conversation, I have been able to learn a bit more than I knew before because reading has TAUGHT me. What I CAN understand, I work to implement and use to my benefit in the sincere desire and hope that perhaps next year or the next, I just MIGHT be able to demonstrate, intelligibly, what I have learned AND SHOW you, just how grateful I am for presenting it to me.
So, I beg you, please be kind to each other in your arguments and differing opinions. Because you are all setting a fire of enlightenment with your discussions here. The teachings you are putting forth may change the world, if not in this generation, perhaps the one forthcoming. Perhaps the cost you have paid, will be nothing in comparison to the value you are creating.
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Post by Hristo on Apr 11, 2010 11:24:13 GMT -5
After reading again the article, this caught my attention:
"We should be able to create haploid-inducing lines in any crop plant"
Maybe it will work like this:
They somehow create modified (haploid-inducing) line of Yellow Pear then cross it with Black Brandywine. The resulting seeds are haploids. After doubling their chromosomes the seeds are planted. All resulting plants are homozygous lines. Now they only have to screen them and pick the most promising lines. This means new variety/pure line in just 2 growing cycles.
I have no access to the full Nature's article, so this is just a guess.
Edit: Well maybe that homozygous x homozygous line is not good example. Lets make it homozygous (the haploid-inducing line) x heterozygous line.
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Post by ottawagardener on Apr 11, 2010 11:52:38 GMT -5
You know, I used to have a subscription to Nature but understanding it was a full time commitment. However, I think I still have access and now I'm dying of curiosity about what it is that this article actually says. If I actually get around to doing this, I'll report back my semi-ignorant opinion  Jo: I hear you about learning. The best way to learn is to teach. |
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Post by DarJones on Apr 11, 2010 12:49:05 GMT -5
You are very close to the concept Hristo. You would create a haploid inducing line out of any tomato even yellow pear. Then you would make a cross of that line with any heterozygous line. With a bit of manipulation, you would wind up with seed that are homozygous but only have chromosomes from the heterozygous line. The end result is that 2 generations would produce a fully homozygous plant. This has fascinating potential for producing hybrids. The reason it is so important is that instead of having to grow 500,000 plants to pick out the 4096 that represent all the homozygous combinations, you could instead grow roughly 20,000 plants with near 100% probability that all of the 4096 combinations would be included.
Still, it is best not to overplay the potential. This is just one possible tool in a plant breeders workshop. It won't take the place of hard work and an occasional burst of insight. This is one place where men like Burbank should be an inspiration for all of us. Who else would have conceived of a thornless blackberry or a seedless cherry/plum.
Here is an interesting tip. Cross Pencil Cob corn with Hickory King. See what you get. This gives one of the best examples of heterosis that I know of.
DarJones
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Post by jonnyyuma on Apr 11, 2010 13:16:59 GMT -5
Hello, I hope this works. Please see attachment. It is in .pdf format. I am not a professional plant breeder, just want to make that clear, but I work in that field currently and do breeding in watermelon, melon and cowpea for fun. I also like to do bulk selection in beans and tomato because I dont' get many crosses in those types and I can screen many different lines side by side and save space. Hrsito, I emailed the study director on this paper to see about the issue of "sex" genes that you bring up. I know it is a big issue in the current protocol for haploid production. I will see what they say, if they say anything, and post it here. Thanks Jonny Attachments:
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