Hello fellows,

I hope you all feel good, i miss the talk with Tom Hill about breeding methodologies, quantitative genetic, the difficulty to bred true the traits we are looking for in drug Cannabis, yield and terpenes profiles for example.

For those who have followed Tom Hill posts on this subject, you probably remember one of his advice to use Selfing in order to have more success in fixing traits.

Im not aware of any sex linked genes in Cannabis and in a preservationist point view i think its good to save as much genetic material as possible but i ask the question :

What is the importance of the Y chromosome in Cannabis ?

A few reminders of the previously talks :

Chimera on the myth of cubing (backcrossing) :

Backcross Breeding –
A type of breeding that involves repeated crossing of progeny with one of the original parental genotypes; cannabis breeders most often cross progeny to the mother plant. This parent is known as the recurrent parent. The non-recurrent parent is called the donor parent. More widely, any time a generation is crossed to a previous generation, it is a form of backcross breeding. Backcross breeding has become one of the staple methods clandestine cannabis breeders use, mainly because it is a simple, rapid method when using greenhouses or grow
rooms, and requires only small populations. The principle goal of backcross breeding is to create a population of individuals derived mainly from the genetics of one single parent (the recurrent parent).

The donor parent is chosen based on a trait of interest that the recurrent parent lacks; the idea is to introgress this trait into the backcross population, such that the new population is comprised mainly of genetics from the recurrent parent, but also contains the genes responsible for the trait of interest from the donor parent.

The backcross method is a suitable scheme for adding new desirable traits to a mostly ideal, relatively true-breeding genotype. When embarking on a backcross breeding plan, the recurrent parent should be a highly acceptable or nearly ideal genotype (for example, an existing commercial cultivar or inbred line). The ideal traits considered for introgression into the new seed line should be simply inherited and easily scored for phenotype. The best donor parent must possess the desired trait, but should not be seriously deficient in other traits. Backcross line production is repeatable, if the same parents are used.

Backcross breeding is best used when adding simply inherited dominant traits that can easily be identified in the progeny of each generation (example 1). Recessive traits are more difficult to select for in backcross breeding, since their expression is masked by dominance in each backcross to the recurrent parent. An additional round of open pollination or sib-mating is needed after each backcross generation, to expose homozygous-recessive plants. Individuals showing the recessive condition are selected from F2 segregating generations and backcrossed to the recurrent parent (see example 2).

Example 1– Backcrossing: Incorporating a dominant trait

Step1– Recurrent Parent × Donor Parent
|
V
F1 Hybrid generation

Step 2 – Select desirable plants showing dominant trait, and hybridize selected plants to recurrent parent. The generation produced is denoted BC1 (some cannabis breeders break from botanical convention and denote this generation Bx1. BC1= Bx1).

Step 3 – Select plants from BC1 and hybridize with the recurrent parent; the resulting generation is denoted BC2.

Step 4 – Select plants from BC2 and hybridize with the recurrent parent; the resulting generation is denoted BC3.
.

Example 2 Backcrossing: Incorporating a recessive trait

Step1– Recurrent Parent × Donor Parent
|
V
F1 Hybrid generation

Step 2 – Select desirable plants, and create an F2 population via full sib-mating.

Step 3 – Select plants showing the desired recessive trait in the F2 generation, then hybridize selected F2-recessive plants to the recurrent parent. The generation produced is denoted BC1.

Step 3 – Select plants from BC1, and create a generation of F2 plants via sib-mating; the resulting generation can be denoted BC1F2

Step 4 – Select desirable BC1F2 plants showing the recessive condition, and hybridize with the recurrent parent; the resulting generation is denoted BC2.

Step 5 – Select plants from BC2, and create an F2 population via sib-mating; denote the resulting generation BC2F2.

Step 6 – Select plants showing the recessive condition from the BC2F2 generation, and hybridize to the recurrent parent; the resulting generation is denoted BC3.

Step 7 – Grow out BC3, select and sib-mate the most ideal candidates to create an F2 population, where plants showing the recessive condition are then selected and used as a basis for a new inbred, or open-pollinated seed line.

This new generation created from the F2 is a population that consists of, on average, ~93.7% of genes from the recurrent parent, and only ~6.3% of genes leftover from the donor parent. Most importantly, one should note that since only homozygous-recessives were chosen for mating in the BC3F2 generation, the entire resulting BC3F3 generation is homozygous for the recessive trait, and breeds true for this recessive trait. Our new population meets our breeding objective. It is a population derived mainly from the genetics of the recurrent parent, yet breeds true for our introgressed recessive trait.


Backcross derived lines are expected to be well-adapted to the environment in which they will be grown, which is another reason backcrossing is often used by cannabis breeders who operate indoors. Indoor grow rooms are easily replicated all over the world, so the grower is able to grow the plants in a similar environment in which they were bred. Progeny therefore need less extensive field-testing by the breeder across a wide range of environments.

If two or more characters are to be introgressed into a new seed line, these would usually be tracked in separate backcross programs, and the individual products would be combined in a final set of crosses after the new populations have been created by backcrossing.

The backcross scheme has specific drawbacks, however. When the recurrent parent is not very true-breeding, the resulting backcross generations segregate, and many of the traits deemed desirable to the line fail to be reproduced reliably. Another limitation of the backcross is that the “improved” variety differs only slightly from the recurrent parent (e.g., one trait). If multiple traits are to be introgressed into the new population, other techniques such as inbreeding or recurrent selection may be more rewarding.

Hope that's a little more clear......
Respectfully,
-Chimera

~~~

and a some quotes from Tom Hill :

The most useful measure of homozygosity is the inbreeding coefficient, F. This coefficient takes a value near zero in most large random-mating populations, and the coefficient increases toward unity under sustained genetic assortive mating. Self-fertilization (one individual in each generation in each family) leads to very rapid increases in homozygosity. Starting with a heterozygote (F=0.50), F takes the values 0.75, 0.875, 0.9375, 0.9688, 0.9844, 0.9922, ... in successive generations of selfing, thus exceeding 0.90 in the third generation. Under continued mating of 2 individuals per family (full sibs) each generation, F is not expected to exceed 0.90 until the eighth generation. With continued mating of 4 individuals per family (double first cousins), F is not expected to exceed 0.90 until the seventeenth generation and rates of increase in F with 8 individuals per family (quadruple second cousins) and 16 individuals per family (octuple third cousins) are much slower yet. The rate of increase in F is so slow with more than 16 mating individuals per family per generation that such matings are of essentially no consequence in concentrating favorable alleles in selection programs in outcrossing species. It is therefore not at all surprising that breeders of plant species nearly always choose schemes featuring very close inbreeding. Selfing schemes (one parent/generation) are by far the most common in breeding outcrossing plants, and the usual goal is to develop numerous highly homozygous lines that are first evaluated by top crossing to identify lines with good general combining ability, followed by testing specific combinations of pairs of lines to identify the very few pairs that have the potential to produce truly excellent single-cross hybrids

~~~

Selfing is approxately 3times more intensive than full sib mating [...] ie s3=f9 +/-

~~~

Self 5 outstanding individuals, rank them according to their progeny, the one that has the most consistant progeny will go through a quick backcrossing method (use as a recurrent parent) without running into the problems that Chimera outlined in myths about backcrossing. Boom, you have your precious Y, and you have completed in 4 cycles a far superior product than what anyone would lay odds on you could do in 9, using any other method.-Tom

~~~

Selfwell Cubewell. If a plant selfs well,,that is to say that many of her progeny upon selfing, resemble her, that is because she is homozygous across many traits. These are the plants you then plug into many areas of breeding, in the case of the backcross, in about 3, you will have that mother (recurrent parant who also selfs well) giving rise to a population that looks very much the same as her selfing progeny did, but with males.

You'll get that no matter the donor parent (the original; male you use) so it doesn't really matter much. Is this the way the backcross is traditionally used in breeding? NO, but who cares it is completely valid. The only part that would be taken out in real breeding would be the reintroduction of the Y [...]

~~~

Let's say you have 5 individuals you really like, and want to breed them all. Self them first, and rank their progeny. Individual 1 has 1 of 30 that is similar to mom, plant 2 has 3, but plant 4 has 15 individuals in her S1 progeny that are similar to mom. Okay so then we can say that plant 4 is most homozygous of the group. Therefore, plant 4 will extremely likely be the best plant to breed with, be it repeating the self, using it as a recurrent parent in a backcross, crossing it out, no matter, the vast majority of the time plant 4 because it selfs well will have the highest breeding worth of all those plants we genotyped via selfing.

let's say you're deep into that half-sib family selection I proposed to Matt earlier, or my favorite (because it is most efficient) the pedigree method. You will be faced with at times the decision to can a family due to it's failure to be homogeneous.. When all of the sudden, the one plant you breed to in the family delivers the lottery. So yes, even though plant number 2 is not the most homozygous in the group it doesn't necessarily mean it's time to give up on that family. These are the decisions a breeder is faced with, possibly according to the numbers he can handle. But none of that translates to giving up on or arguing against the science altogether by any stretch of the imagination.

~~~

Now take your 5 favorite clones and plug them into a pedigree selection method. Self 5 clones, grow out their progeny in 5 seperate plots. Evaluate those plots as you guys are use to. Seek out "the best" of those 5 plots, self those individuals again. Repeat this process, you'll not need to go far I assure you (certainly not beyond 3 gens) if you know where to start you'll be in the money so to speak imediately (S1). Clear winning families will emerge 3 times more rapidly than any other breeding method.. So when someone says,,, fuck feminized seed they only have this use or that, please, tell them they are absolutely full of shit. They have zero idea of how to best take advantage of the maths as they pertain to selection methods in plant breeding. Not numbers, method.- Tom

~~~

... but back to Allard-

"Selfing schemes (one parent/generation) are by far the most common in breeding outcrossing plants, and the usual goal is to develop numerous highly homozygous lines that are first evaluated by top crossing to identify lines with good general combining ability, followed by testing specific combinations of pairs of lines to identify the very few pairs that have the potential to produce truly excellent single-cross hybrids"

The selfing of candidates is nothing more than a genotype test - a view into the genetic make-up of the plants, those that "produce the most individuals similar to the female parent" are most homozygous and therefore of higher breeding worth because they are more prepotent (tend to pass these traits on to their offspring).

The top crossing he speaks of to determine those with good GCA would be then if you took all of your most homozygous lines/individuals and crossed them all out to a known heterozygous line/individual (the top cross parent) and observed the progenies. The idea being that those (homozygous lines/individuals) that cross well to both A and a (in the heterozygous line/individuals), will tend to be the best candidates to test against many other lines as well.

I can't imagine many folk here bothering with all that, but bothering with seeking out your most homozygous candidates before testing specific combinations, or using them as recurrent parents in a backcrossing scheme, etc etc, is most definitely worth you time and effort imo. -T

~~~

if an acceptable percentage of the progeny from the original parent upon selfing show the trait/s, then the original parent is worth trying in the outcross, no need to look at reversing S1's. Otherwise, yes, test S1's via reversal and observe those progeny etc etc. And therein lies one of the main values of breeding utilizing selfing via reversal btw.. If it proves out that the parent we'd like to use, is terribly heterozygous, the progenies as we continue on with selfing, become homozygous 3 times more efficiently than under any male/female breeding scheme.-T

~~~

[...] I used the 50% of progeny resembling mom purposely. We want to see a drastic difference from the mean, there should and will be a great departure from the norm before we can honestly grant it value. If we were to get excited about some 1-5% gain in apparent genotypic value, then we'd be kidding ourselves as much as someone making selections based on intuition. Yes, you will see a drastic difference in these tests, and you will make moves accordingly, and walk away with a genuine pat on your back, knowing that you've truly done your best.

[Adze]

sirius haze,

Interesting collection of quotes, good sources and good information. But it seems to me that your title is a bit misleading, as these quotes tend to prove that one doesn't need a male to produce seed, in fact not using a male produces more progress toward one's breed goals. The males are introduced only to make regular seed, hardly proof of their importance.

[VerdantGreen]

the only real useful thing about males, imo, is that you can then breed cannabis without any special chemicals etc that you generally need to reverse females.... so on a desert island i would prefer regular seeds to play with and breed.

apart from that, i dont see much advantage to using males. the major traits we look for in drug cannabis are expressed only by the females - so it is much easier for us to evaluate the phenotypic worth of a female than it is a male. males can only really be evaluated by testing projeny.

VG

[vostok]

I am on that 'Desert Island' ..? I believe we all are, as time goes by, seedbanks and breeders prefer to sell us feminized autos, for a guaranteed return to any business is REPEAT business, thats right they are in it for the cash, lock out the males and regular seeds soon you will only get again those feminized autos ..
already this is happening in the general cannabis growing market, you only need one or two dodgy seedbanks or breeders to throw doubt over their viability, and thats now happening on a daily basis, herding the market to a central point, of a market male free
...already on many breeders sites the 'new' addition to the these sites is

""WE ONLY SELL REGULAR CANNABIS SEEDS ONLY, NOT PLANTS OR WEED"

You gotta ask ...Why should they have to put that up?

[VerdantGreen]

if breeders are in it for the cash then they will sell what there is the greatest demand for - and that is fems. most growers dont want anything to do with males plants because they are scared of ruining their sensi cash crop.

making fem seeds is actually a lot more work than making regulars seeds.

you can get repeat business by making regular F1s.

all breeders have the right to make whatever seeds they want, and all growers have the right to buy any seeds that they want. dont try and make it into a conspiracy!

VG

[Adze]

Anyone who thinks that they are a breeder and can't figure out how to make seed starting with feminized seed best consider a new profession. I paraphrase Tom Hill here, but I can find the quote if it helps. And of course there are many, many sources of regular seed, lots of male plants available and thousands of us with regular seed. No one is going to control the market effectively, not in my lifetime. That of course, has absolutely nothing to do with the importance of male genes to cannabis as a plant.
Verdant Green is quite right, it may be the best male is a female that allows you to see some of her genetic traits and who is then reversed.

[MJPassion]

Originally Posted by VerdantGreen

the only real useful thing about males, imo, is that you can then breed cannabis without any special chemicals etc that you generally need to reverse females.... so on a desert island i would prefer regular seeds to play with and breed.

apart from that, i dont see much advantage to using males. the major traits we look for in drug cannabis are expressed only by the females - so it is much easier for us to evaluate the phenotypic worth of a female than it is a male. males can only really be evaluated by testing projeny.

VG

Nice answer. Pretty much sums up my understanding of the issue.

Though, I do prefer regular seed. I enjoy watching the males grow in the window during the winter. They make good trimmins for the worms to munch on.

[Sam_Skunkman]

Originally Posted by Adze

Anyone who thinks that they are a breeder and can't figure out how to make seed starting with feminized seed best consider a new profession. I paraphrase Tom Hill here, but I can find the quote if it helps. And of course there are many, many sources of regular seed, lots of male plants available and thousands of us with regular seed. No one is going to control the market effectively, not in my lifetime. That of course, has absolutely nothing to do with the importance of male genes to cannabis as a plant.
Verdant Green is quite right, it may be the best male is a female that allows you to see some of her genetic traits and who is then reversed.

You can reverse any male to have it express female flowers to see what they are passing on to progeny, and unlike with a STS reversed female to male the reversed can be smoked to judge potency, type of effects, and terpenes.
The reason most seed makers don't like males is they are harder to evaluate then females and you can get a higher price for all female seed.
I would suggest that as more and more varieties are clone selections that stood out but if there is no male means that to make that variety of seeds or hybrids they are transforming a elite female clone to male to get pollen they hope is like the mother clone? With poly-hybrids this is less and less likely, as the clonal mother was a poly-hybrid and the off spring of F2-6 parents even if you self the clone a transformed male from female clone to the same female clone, the seeds will give plants that express many parents and generations in the hybrid. They will not be similar, to make similar use lines that are pretty homogenous for the target traits like a selected land race and cross it with a very different land race, you get F1 seeds that can be very similar to each other, a blend of the two parents. Self them and you get F2 with 25% like the mom, 25% like the dad and 50% somewhere between them and the F1.
I know most folks know this but what the hell....
I see people calling all female seeds made from two different female clones as selfed, but selfed is a single female using the same female's transformed pollen to make seeds, and they will not be the same as the parent, they are the equivalent of the F2 or F5 what ever they are, with poly-hybrids few even know.
If all cannabis was all female seed only it would be totally dependent on man for reproduction, and if man were gone so would Cannabis be gone. I don't think man has plans to die off, or that man has the ability to make all Cannabis seed in the world all female at least not yet....

-SamS

Originally Posted by Adze

sirius haze,

Interesting collection of quotes, good sources and good information. But it seems to me that your title is a bit misleading, as these quotes tend to prove that one doesn't need a male to produce seed, in fact not using a male produces more progress toward one's breed goals. The males are introduced only to make regular seed, hardly proof of their importance.

yes you're right im sorry the title is a bit misleading, in fact i forgot to put the question mark in the title.

Im curently reading papers about evolution of X and Y chromosomes in plants, parallels between the sex determination systems, as well as the organization of sex chromosomes, in different species, between animals and plants, but even if im convinced that Selfing is the quickest breeding technique to true bred lines, i also think we have to reintroduce the Y chromosome later in a preservationist view, for the future because we never know how the future will be and to restore the natural dioecy condition of the Cannabis species. Im speaking of the long term lines who will be passed to the next generations, our children and grandchildren not the gynoecious lines the customer want. Im still searching other important reasons to use the Y chromosome, i never saw anyone prooving sex linked gene in Cannabis but i heard some breeders have theory about important traits passed by the males to the progeny, nonetheless i never read concret talk about it.