[VerdantGreen]

fascinating stuff guys, just so i know i am following this....

we can take an elite clone, reverse it to get pollen, then use tissue/anther culture to create a doubled haploid plant.

then if you make S1 seeds of the DH you will have a true- breeding seed version of the elite clone?

am i on the page or should i go back and school myself some more?

VG

[GMT]

lol Tom, only you would consider those to be low numbers.

VG, elite, apply chem to prevent recombination, reverse, magic and grow haploid, poison it to get DH.
Grow almost a hundred more the same way, select one, reverse it, pollinate all others, grow one seed from each, (or if you have access to dna testing even easier), hey presto, parents identified to give you endless copies of elite.

[mofeta]

Wow this thread just jumped up a couple levels! I'm impressed.

Hi Tom

Thanks for the link to the paper above:

Reverse breeding: a novel breeding approach based on engineered meiosis

That is the most concise, easy to understand paper I've read on the subject. I highly recommend it to anyone interested in the subject.

For those of you who do read it, look up and understand every term you don't know. It could take a long time, but when you are done you will have learned a LOT.

Scientists do not employ strict terminology for looks, it is essential for doing science. The terms have very specific, precise meanings, folding a complex concept into a small package that can be dealt with by our feeble minds. You really just absolutely cannot understand the larger conceptual canvas without a firm understanding of each and every term.

When I first started out reading technical papers, it would take me days, weeks, even months and years to fully grasp one paper. There are papers from the truly grueling disciplines (physics, math etc.) that I have been reading for years and I still don't fully comprehend them. It is worth it though, as the terms used in a specific discipline are finite- so after you spend a couple weeks plodding through your first genetics papers, the next one will only take a few days, and then after you read enough, you get it as soon as you read it.

Remember, you aren't reading a novel or a newspaper article. I can read those types of things at close to 1000wpm. In a technical paper (especially in a discipline I'm unfamiliar with) that can drop to a sentence a day. I never proceed past a word I don't grasp, and with a word that encapsulates a complex concept, I might have to read tens of thousands of words from textbooks etc to really understand the word.

One thing to look out for though is that a term that has a certain meaning in one discipline may have a different meaning in another discipline, so make sure you look up the term in the correct context.

The one thing that doesn't change though is the math. It is universal and is the epitome of the "conceptual packaging" I mentioned above. For the stuff we are talking about on these boards, I recommend a focus on statistics. Having a good grasp of stats unlocks the meaning of many a important scientific concept.

Once again, I am really impressed with the level of discourse on this thread, thanks to everyone for your thoughtful contributions.

[mofeta]

One more thing-

Once you read the paper Tom linked to, you might want to read about recent advances in this area.

Here is a link to a thread I made some time back that discusses them:

cenh3 null mutation for Cannabis?

I never finished the thread, because the view count was too low to justify the work involved, but the links to the papers are in the thread.

[wrongwrong]

this is the patent to go with that paper

https://www.freshpatents.com/Reverse-...0060179498.php

and I like how wijnker terms it;

Reverse breeding approach : simplifying inheritance patters
Erik Wijnker
Laboratory of Genetics, Wageningen University, WU
Erik.Wijnker@wur.nl
A plant breeders’ most important goal is the efficient creation of desirable allele combinations for the
improvement of elite hybrids. New allele combinations are obtained through meiotic recombination, a
process in which meiotic crossovers and chromosome segregation lead to gametes of unpredictable genetic
make-up. This unpredictable genetic composition in certain cases works against breeders when desired
allele combinations are lost from one generation to the other. Reverse breeding is a new plant breeding
technique that was designed to effectively simplify chromosome inheritance by transiently suppressing
meiotic crossovers. We show that suppression of crossover recombination indeed leads to offspring of highly
predictable genetic composition. This opens doors to very interesting new breeding applications. For
knocking down the crossover machinery there are various possible methods. We recently used an RNAiconstruct
targeted at a gene essential for crossover formation. Since crossover suppression is only required
during one step in the breeding process (i.e. during gamete formation), and the transgene segregates in
offspring, Reverse breeding generates breeding lines that are free of transgenes.

[mofeta]

Back when my parents were attending university, the elucidation of the structure of DNA was brand new. Even the simplest understanding of the genetic code did not exist.

The highest level of understanding of the mechanisms of heredity was the field of cytogenetics (The branch of biology that deals with heredity and the cellular components, particularly chromosomes, associated with heredity. def from TFD).

I find that today, the emphasis on DNA/molecular genetics makes for students that are lacking in the understanding of this field.

It is not unusual to talk to a student that can tell you all about codons, initiator elements, transcription bubbles etc, but can't tell you what these images are:

[wrongwrong]

Originally Posted by mofeta

Back when my parents were attending university, the elucidation of the structure of DNA was brand new. Even the most simplest understanding of the genetic code did not exist.

The highest level of understanding of the mechanisms of heredity was the field of cytogenetics (The branch of biology that deals with heredity and the cellular components, particularly chromosomes, associated with heredity. def from TFD).

I find that today, the emphasis on DNA/molecular genetics makes for students that are lacking in the understanding of this field.

It is not unusual to talk to a student that can tell you all about codons, initiator elements, transcription bubbles etc, but can't tell you what these images are:

View Image

View Image

is it an inversion loop off the top of my head it shows 2 nonrecombinants (as it states..) one is mutated? I think the other 2 imbalanced ones show a half of the original each? but I let myself down on this sort of thing.. up on breeding practices and that but this stuff gives me headaches at times!! last one like double cross over.

[Nunsacred]

Originally Posted by VerdantGreen

fascinating stuff guys, just so i know i am following this....

we can take an elite clone, reverse it to get pollen, then use tissue/anther culture to create a doubled haploid plant.

then if you make S1 seeds of the DH you will have a true- breeding seed version of the elite clone?

am i on the page or should i go back and school myself some more?

VG

That's the general gist of it, yes.

Once you've made your DH plants, you still have to select good performers from them.
But this is (supposedly) really easy in DH populations because :

"by choosing a great pheno from DH plants you're also choosing a great parent at the same time."

Without falling into any jargon, that's the theory.
It's a big deal.

However, things aren't that simple in reality, mainly because there is much more to a ganja plant embryo than the presence of 0,1 or 2 copies of the n=10 haplotype.

[wrongwrong]

Originally Posted by TomHill

IE, I have nerd friends who are better at the maths than I seguro, and I am guilty of merely browsing over the material from time to time (though I occasionally speak the language that comes from meticulous review). But I do from time to time advertize myself as a decent translator and thus my question, are the maths in my head correct? That when we speak of X number of DH plants we are speaking of products, and not (haploid) inputs, in which case the numbers required become exponentially more demanding? Many thanks, it's truly refreshing to stick our junk on the guillotine from time to time to make sure we are on the same page sir. -T

would that not get you back to the 1 in 1000 (1024) odd shot? ie 2 to the power of N etc...

So I have it as if we were starting from scratch

say you're looking for something with 10 genes matched, in a diploid state you would need about 1 mil to see everything and select the one you want..

in a haploid state this would be 1024 (easily get down in numbers by disguarding all mutants, undiserable recessives etc etc)

but I'm guessing you would be doing this from some selfed lines.. so the numbers req'd would be a lot lower....

and then you are down to the 98 DH's

[GMT]

hmmm, before we get to counting stuff, does anyone know if what is required to prevent recombination in canna, has been identified and is available? I know for a bunch of stuff it has, but if its not done for canna, then the numbers are going to get much bigger.
Also where is the 98 coming from? I'm still only counting 96, seem to be missing 2 somewhere.