do you think the high thc genotype is a recessive gene combination?

[TheFarm]

just wanted to know your thoughts on this since I had been thinking about anecdotes of potent marijuana crops becoming nonpotent after generations when left to open pollination as in a situation where the isolated fertile outdoor grow site was abandoned?

 

[stoned-trout]

bump.....

 

[TheFarm]

What could the other reasons be for the change in phenotype

 

[Dropped Cat]

I have read anything under 7% THC is low. But left to its own devices
cannabis will go flat.

People make cannabis more potent. Recessive? Yup.

Breed more. Preserve what you can.

 

[dannykarey]

I think it might have been at one time.......But since people in the early hash producing areas started selecting/breeding plants for trich/drug production for hundereds/thousands of years.......We now have what we know as pot today IMHO.

It all came about through human intervention or selective breeding IMHO.

Danny

 

[mojave green]

dunno, my lapis mtn indica is pretty potent. it's pretty close landrace.

 

[IntelliGeneS]

If you mean the THCA synthase gene... no, probably Dominant or Codominant, since any allele coding for a functional THCA synthase should result in some conversion of CBGA to THCA.

If you mean the (somewhat poorly defined) concept of "high THC phenotype"... no, I'm fairly sure based on reasonable proposed cannabinoid pathways that THC level phenotype is driven by a multitude of simple genes or (more likely) QTLs impacting the expression of cannabinoid biosynthesis proteins.

 

[G.O. Joe]

There are other factors for cannabinoids, like growth habit - if the plants get all weedy and leafy, the cannabinoids are going to go down. With or without outside pollen, it will be survival of the fittest - probably the fastest to the sun.

 

[theother]

There are other factors for cannabinoids, like growth habit - if the plants get all weedy and leafy, the cannabinoids are going to go down. With or without outside pollen, it will be survival of the fittest - probably the fastest to the sun.

I think this is it exactly. Nothing in recessive or dominant genes, just natural selection in less than ideal conditions. Whatever exhibits the trait that keeps it alive goes to seed. Almost definitely not gonna be a quality we are looking for.

I think when people talk about a landrace they mean a cultivar that had some human intervention". NOT exactly an ibl but not by any means just left out in nature to do it's thing.

 

[EclipseFour20]

Wouldn't it depend on which gene/trait that is favored by the "natural selection" process? Of course not all "good" traits are sourced from a "dominant gene"--take a peak at the human population (good example of "natural selection")...and ask yourself "are there more "gorgeous" or "ugly" people on this planet?" Cruel but true.

Nature seems to be dynamic and a good argument can be made that: If left alone--natural selection favors a "recessive" gene/trait over a particular "dominant" one. Certainly this may not be true 100% of the time--but it does explain why certain plants if left alone in the "wild" can eventually change/evolve to a new "plant subspecies". Is it due to the dominance of a "recessive" gene or suppression of a "dominant" gene?

If "natural selection" favors the "recessive" gene/trait (and disfavors the "dominant" one) then eventually over time (millennium or two) would the two just swap? Recessive would now be "dominant" and vice versa; maybe not on the scale of the earth's swapping north & south poles...but overtime--things do seem to cycle from "dominant" to "recessive" (swap).

And then add a super wild card variable to the equation: human intervention (aka cultivator/breeder). Our actions can trump nature.

 

[TheFarm]

What are QTLs?

 

[Jhhnn]

dunno, my lapis mtn indica is pretty potent. it's pretty close landrace.

I think that what we call landraces are local cultivars of drug cannabis. Farmers have worked them in traditional ways with open pollination and female selection for many generations, for thousands of years. They even introduce backcrossing at a population level when they grow 2012 and 2011 seeds together, for example. Results vary by environment, intensity of effort, skill of selection & blind luck as well.

Somewhere at some time in the very distant past, humans discovered psychoactive properties in a population of cannabis. They liked it, kept it, worked to bring out that quality & carried it all over the world. If we think about it at all, high THC content is only a survival factor for plants under human cultivation. It's the same as other factors humans choose to perpetuate & enhance with any crop from apples to zucchini. Even in hospitable environments, populations that escape & become feral, ruderal, will respond to environmental conditions differently than under human management. W/O human selection, natural selection takes over.

 

[Betterhaff]

QTL = Quantitative Trait Loci.

It has been suggested that cannabinoid synthesis is controlled by 4 different loci and with at least 2 of these the functional alleles are co-dominant. I think it’s also suggested that these loci are monogenic.

At the O loci, functional alleles will produce canabinoids but can be paired with nonfunctional alleles which would create an array of cannabinoid concentrations (lower) and 2 nonfunctional alleles can be paired which would produce no cannabinoids.

At the B loci there may also be various alleles in regards to the concentration and type of cannabinoids they’re capable of producing. These would determine the overall ratio and %. Two high concentration vs a high and a medium, a medium and a medium, a medium and a low, etc. because of co-dominance.

The frequency of these alleles could also be a factor.

In the wild there is no selective pressure for high cannabinoid concentrations (other than man), only natural selection, so all of the above may come into play. If an allele is low frequency for high cannabinoid production without selective pressure it will lose out to alleles of higher frequency that may have lower cannabinoid production capabilities. Of course other factors come into play such as the over all health of the plants carrying these traits. A sickly plant with all the proper alleles in place for high cannabionoid production will lose out to healthier plants without that configuration.

This is just me thinking out loud, someone with more knowledge and/or expertise please correct or elaborate.

 

[IntelliGeneS]

Wouldn't it depend on which gene/trait that is favored by the "natural selection" process? Of course not all "good" traits are sourced from a "dominant gene"--take a peak at the human population (good example of "natural selection")...and ask yourself "are there more "gorgeous" or "ugly" people on this planet?" Cruel but true.

Nature seems to be dynamic and a good argument can be made that: If left alone--natural selection favors a "recessive" gene/trait over a particular "dominant" one. Certainly this may not be true 100% of the time--but it does explain why certain plants if left alone in the "wild" can eventually change/evolve to a new "plant subspecies". Is it due to the dominance of a "recessive" gene or suppression of a "dominant" gene?

If "natural selection" favors the "recessive" gene/trait (and disfavors the "dominant" one) then eventually over time (millennium or two) would the two just swap? Recessive would now be "dominant" and vice versa; maybe not on the scale of the earth's swapping north & south poles...but overtime--things do seem to cycle from "dominant" to "recessive" (swap).

And then add a super wild card variable to the equation: human intervention (aka cultivator/breeder). Our actions can trump nature.

Selection pressure (natural or artificial) does not usually correlate to gene expression type directly. Recessive alleles are easier/quicker to fix in a population if they are desired or confer reproductive or survival advantage, but this is because it is easier to fix homozygous recessive individuals since there cannot be heterozygous individuals expressing the same desired/advantageous phenotype. The expression type of a gene is typically a function of its method of action directly.

What are QTLs?

QTL = Quantitative Trait Loci.

It has been suggested that cannabinoid synthesis is controlled by 4 different loci and with at least 2 of these the functional alleles are co-dominant. I think it’s also suggested that these loci are monogenic.

At the O loci, functional alleles will produce canabinoids but can be paired with nonfunctional alleles which would create an array of cannabinoid concentrations (lower) and 2 nonfunctional alleles can be paired which would produce no cannabinoids.

At the B loci there may also be various alleles in regards to the concentration and type of cannabinoids they’re capable of producing. These would determine the overall ratio and %. Two high concentration vs a high and a medium, a medium and a medium, a medium and a low, etc. because of co-dominance.

The frequency of these alleles could also be a factor.

In the wild there is no selective pressure for high cannabinoid concentrations (other than man), only natural selection, so all of the above may come into play. If an allele is low frequency for high cannabinoid production without selective pressure it will lose out to alleles of higher frequency that may have lower cannabinoid production capabilities. Of course other factors come into play such as the over all health of the plants carrying these traits. A sickly plant with all the proper alleles in place for high cannabionoid production will lose out to healthier plants without that configuration.

This is just me thinking out loud, someone with more knowledge and/or expertise please correct or elaborate.

Thanks Betterhaff for explaining QTL, I forget sometimes that these acronyms are not widely known.

I would posit that 4 genes are necessary to enable the synthesis of cannabinoids based on the proposed cannabinoid biosynthesis pathway below:

From van Bakel [FONT=AdvOT65f8a23b.I][FONT=AdvOT65f8a23b.I]et al[/FONT][/FONT]. [FONT=AdvOT65f8a23b.I][FONT=AdvOT65f8a23b.I]Genome Biology [/FONT][/FONT]2011 -see http://genomebiology.com/content/pdf/gb-2011-12-10-r102.pdf

You can see that (putatively) 4 enzymes - an olivetolic acid-producing polyketide synthase (OLS) , an aromatic prenyltransferase (PT), CBDA synthase (CBDAS), and THCA synthase (THCAS) work together in a pathway which converts hexanoyl CoA and prenyl side-chains into either THCA or CBDA.

However I'd suggest that the existence of different ratios of THCA to CBDA seen in drug cultivars of Cannabis indicate that there are some (allelic) genes which code for different forms of these enzymes which are more or less efficient, and/or that there are differences (which show up as different alleles) in promoter and/or other regulatory regions which change the expression of the genes involved. Also there might be some transport proteins involved in the pathway which are not yet fully understood.

Therefore, THC and CBD levels are likely to not be simply (qualitatively, or on/off) controlled. Instead they are probably controlled by many different gene loci which have quantitative effects (QTLs).

 

[EclipseFour20]

So what you are expressing is, recessive traits don't matter. Even when the parents (two different "gene sources") have different "gene expressions"?

 

[TheFarm]

So IntelliGeneS, do you see it like the overall growing theory of various inputs with the production generally limited to the lowest input according to need?

 

[Sam_Skunkman]

THC production and the amounts produced are indeed controlled by many genes, the genes that control which Cannabinoiod is produced, the genes that make for lots of sites of production, (trichomes, size and amounts) as well as many more. And then the environment needs to be kind and allow full maturation without to much cold and wet, as well as sufficient nutrition, and general health, as well as production of unseeded crops.
I really doubt high THC is recessive as if you combine a high THC variety with a low one the progeny will normally be halfway between the two parents, to me that does not imply a set of dominate and/or recessive genes controlling this trait.

Betterhaff, is the info you posted from De Meijer's papers? The inheritance of chemical phenotype in Cannabis sativa L.?
-SamS

 

[IntelliGeneS]

So what you are expressing is, recessive traits don't matter. Even when the parents (two different "gene sources") have different "gene expressions"?

Not really, recessive traits always matter (unless they are masked by a dominant allele). I'm saying that since THC and other cannabinoids are products of a pathway made up of enzymes encoded by certain genes, it's unlikely that the alleles coding for functional enzymes are recessive, since having one functional copy of a gene is usually at least enough to have some functional enzyme expressed (making that a codominant gene) if not enough to produce enough functional enzyme that it is not rate-limiting (observed as dominant).

Two parents having different "gene expressions" just have different alleles at one or more gene locus which encode for technically different proteins or cause different levels of expression (more/less transcription, transcription in different tissues, etc.).

So IntelliGeneS, do you see it like the overall growing theory of various inputs with the production generally limited to the lowest input according to need?

This is generally how pathways and metabolomics studies are thought about, yes.

I don't have enough information yet to conclude that cannabinoid balances are primarily (of course, there is Environment and GenotypeXEnvironment impact) the result of several simple genes acting in concert, or a more complex system of promoter/regulatory regions affecting combinations of coding genes. Because of the wide range of THC:CBD ratios which have been reported, I tend to lean toward the latter.

 

[IntelliGeneS]

THC production and the amounts produced are indeed controlled by many genes, the genes that control which Cannabinoiod is produced, the genes that make for lots of sites of production, (trichomes, size and amounts) as well as many more. And then the environment needs to be kind and allow full maturation without to much cold and wet, as well as sufficient nutrition, and general health, as well as production of unseeded crops.
I really doubt high THC is recessive as if you combine a high THC variety with a low one the progeny will normally be halfway between the two parents, to me that does not imply a set of dominate and/or recessive genes controlling this trait.

Betterhaff, is the info you posted from De Meijer's papers? The inheritance of chemical phenotype in Cannabis sativa L.?
-SamS

Sam's making good points that reveal how many things can impact production of a set of pathway products. Since the cannabinoid pathway seems to be mostly expressed in association with trichomes, and trichomes occur mostly on buds, genes which affect the growth of bud sites, bud tissues, and trichomes will of course change the total cannabinoid level phenotype.

The example of an intermediate THC phenotype in the progeny from a High-THC x Low-THC cross indicates to me that there was a rate-limiting step somewhere in the upstream pathway to produce THC. This could be any upstream step, really... the resulting intermediate phenotype is most likely the result of two different codominant alleles for a promoter or an enzyme-coding gene producing some substrate used in the set of pathways leading to THC production (or the THCAS enzyme itself).

 

[TheFarm]

Who says dope makes you stupid? This is like my college endocrinology class where 20 out of 25 pre-med students dropped the class.