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Doubled haploids
- Thread starter mofeta
- Start date
I am thinking about them far from by guess and by golly random pairwise crosses. We know before hand which plants we will recombine into mom I believe -certainly rule out the vast majority. After all, we have the parent, and all available offspring marked. In my understanding the majority of this is done in the lab using marker tech. No more time costly than running over the evening stock charts 
wrongwrong
Member
I am thinking about them far from by guess and by golly random pairwise crosses. We know before hand which plants we will recombine into mom I believe -certainly rule out the vast majority. After all, we have the parent, and all available offspring marked. In my understanding the majority of this is done in the lab using marker tech. No more time costly than running over the evening stock charts
that would be my understanding of it, you look for the markers.. so the 4573 can be whittled down quickly, or if I look at it another way I have easily gone thru a few thousand plants/seedlings etc in my 5 years of line breeding.. and there's no way they will end up as homogyzous as the ones here would.,so though high enough numbers not as high as I first feared .
been trying to get my mitts on this
Edit: got my mitts on it!
http://webcache.googleusercontent.c...8/91keshi/Public/File/48/44-4/pdf/ng.2203.pdf
Figure 2 provides a decent visual aid to what I was attempting to communicate, thought the paper was a good read regardless. As well as one of the references from 49-51.
http://classes.uleth.ca/201201/biol4500a/Readings/Rozwadowski_1 (review).pdf
http://classes.uleth.ca/201201/biol4500a/Readings/Rozwadowski_1 (review).pdf
Yeah that's right. I think it would be pretty easy to whittle it down this way.
Another thing to keep in mind is that even without looking at markers, if you just mated the DHs and looked at progeny, you wouldn't have to do all 4573 matings. There would be a sample size much smaller than that that would have a very high probability of finding the complementary parents.
Hi Tom
Wow another great paper to read! It addresses many of the things I have been thinking about in regards to this subject. I just skimmed the beginning and look forward to reading the whole thing.
I had been wondering what the frequency of production of non-recombinant gametes in a unmanipulated plant was (EDIT: or if it happened at all), and what variables affected this frequency. If there was a high enough occurrence of naturally produced gametes that hadn't undergone crossover, it would make this eminently doable.
This part especially piqued my interest:
Burbank, anyone? If I remember correctly, didn't Burbank believe that seeds from different parts of the plant produce different offspring? And that Mendelians like to ridicule him for that belief?
Anyway, the chance that a significant number of gametes are produced naturally that do not undergo crossover is of huge significance. The plain old DH scheme I presented in the beginning of the thread would be much better than I thought. The presence of naturally non-recombinant gametes would allow for exact reproduction of the desired parent without high tech, just numbers.
Thanks again Tom! I can't wait to read the rest of the paper.
Wow another great paper to read! It addresses many of the things I have been thinking about in regards to this subject. I just skimmed the beginning and look forward to reading the whole thing.
I had been wondering what the frequency of production of non-recombinant gametes in a unmanipulated plant was (EDIT: or if it happened at all), and what variables affected this frequency. If there was a high enough occurrence of naturally produced gametes that hadn't undergone crossover, it would make this eminently doable.
This part especially piqued my interest:
Burbank, anyone? If I remember correctly, didn't Burbank believe that seeds from different parts of the plant produce different offspring? And that Mendelians like to ridicule him for that belief?
Anyway, the chance that a significant number of gametes are produced naturally that do not undergo crossover is of huge significance. The plain old DH scheme I presented in the beginning of the thread would be much better than I thought. The presence of naturally non-recombinant gametes would allow for exact reproduction of the desired parent without high tech, just numbers.
Thanks again Tom! I can't wait to read the rest of the paper.
To be clear, the paper Tom linked to doesn't say that there are naturally produced non-recombinant gametes, it's just that it's discussion of the things that effect the frequency of crossover resonated with what I was thinking about.
The conventional wisdom is that crossover is absolutely necessary for the proper segregation of chromosomes in meiosis (the so-called "crossover assurance"). But, as the paper points out, "In the past, the lack of practical tools for establishing crossover frequencies hampered systematic studies on crossover management in crops. Determining specific crossover frequencies was costly and laborious and was mostly confined to model species."
What if some species produce a few gametes that haven't undergone crossover?
The conventional wisdom is that crossover is absolutely necessary for the proper segregation of chromosomes in meiosis (the so-called "crossover assurance"). But, as the paper points out, "In the past, the lack of practical tools for establishing crossover frequencies hampered systematic studies on crossover management in crops. Determining specific crossover frequencies was costly and laborious and was mostly confined to model species."
What if some species produce a few gametes that haven't undergone crossover?
wrongwrong
Member
I think the link to the Susan Jones article could be the article I have posted in post 84
G
gloryoskie
So what happens next? This is a treasure of information to a novice.
You guys are posting solid gold.
The phrase "Reverse plant breeding success" is so nice.
You guys are posting solid gold.
The phrase "Reverse plant breeding success" is so nice.
Can you expand on this Tom, I've been looking around, and this place in the UK seems to offer the type of services that you are talking about http://www.lifesciences.sourcebioscience.com/genomic-services/sanger-sequencing-service.aspx
but I still don't know what it is that you would actually be asking of such a business, and therefore have no basis on which to evaluate the costs.
but I still don't know what it is that you would actually be asking of such a business, and therefore have no basis on which to evaluate the costs.
http://classes.uleth.ca/201201/biol4500a/Readings/Rozwadowski_1 (review).pdf
look at figure 2. it is clear what plants must be recombined to recapture the original genotype. We have not sequenced the genome here, no need, we are looking at a few markers. Can you see any other combinations on that bottom line that would accomplish the task at hand? I can not, and so we have whittled it down substantially from any of these nightmare maths scenario that you are contemplating, have we not?
look at figure 2. it is clear what plants must be recombined to recapture the original genotype. We have not sequenced the genome here, no need, we are looking at a few markers. Can you see any other combinations on that bottom line that would accomplish the task at hand? I can not, and so we have whittled it down substantially from any of these nightmare maths scenario that you are contemplating, have we not?
I accept that the numbers can be whittled down using these techniques; making the assumption that what prevents recombination in other species will also work with canna. I'm trying to work out if its economically viable rather than merely scientifically viable. In our situation though, wouldn't it be needed to check for 10 markers rather than 3? Also the selecting of the markers in the first place still confuses me without first gaining the genomic reading of the original. How are the markers selected to begin with?
I really believe your misgivings are misplaced. We can do most of this no problem. The real trick is regenerating plantlets from spores.... As those scientists just accomplished with the Siberian permafrost fruit. It's been done, is being done, now it is a matter of protocol to fit. We begin by copying, as usual, and flex as need be. But no, this is by no means out of reach imo. And I am quite willing to bet on it.
Also as far as I can see, this still leads to a dead end. Ie you will only end up with a single sexed line. Therefore the result is not a true breeding line as far as I can see, unless you know of a way to swap one chromosome for another. Unless reversing females in order to reproduce comes under the legal definition of true breeding. Something I doubt somehow but am not sure of.
