Cannabis Chemotypes I, II, and III

[Chemotype]

Cannabis sativa exists in different chemical variants, showing chemical but sometimes also morphological differences, known as chemotypes (Small and Beckstead 1973). Three different principal chemotypes were first identified. The first one was defined as the ‘drug type’ (chemotype I), because its low CBD/THC content ratio, especially due to high THC content. The second chemotype, ‘intermediate’, has both the two main cannabinoids, THC and CBD, in a content ratio close to the unity (typically ranging from 0.5 to 3.0; chemotype II), but usually with a slight prevalence of CBD; the third one, the so-called ‘fibre’, or ‘non-drug’ type (chemotype III), has mainly CBD, an amount of THC lower than 0.3%, and therefore a high CBD/THC ratio, sometimes not calculable due to undetectability of THC (de Meijer et al. 1992). It has been recently demonstrated that all the three main chemotypes can arise simply by segregation at one locus (B) within individual F2 progenies of divergent-chemotype parentals (Mandolino et al. 2003; de Meijer et al. 2003). Today a widely accepted view of the inheritance of these three chemotypes, is based upon the occurrence, at B locus, of two codominant alleles, BD and BT, responsible for the presence of CBD and THC, respectively (de Meijer et al. 2003; Mandolino 2004).


Cited from, Genetics and marker-assisted selection of the chemotype in Cannabis sativa L., Daniela Pacifico, Francesca Miselli, Mirta Micheler, Andrea Carboni, Paolo Ranalli and Giuseppe Mandolino; Molecular Breeding (2006) 17: 257–268.

 

[been]

In the fields of genetics and evolutionary computation, a locus (plural loci) is a fixed position on a chromosome such as the position of a biomarker that may be occupied by one or more genes. A variant of the DNA sequence at a given locus is called an allele. The ordered list of loci known for a particular genome is called a genetic map. Gene mapping is the process of determining the locus for a particular biological trait.

Diploid and polyploid cells whose chromosomes have the same allele of a given gene at some locus are called homozygous with respect to that gene, while those that have different alleles of a given gene at a locus, heterozygous with respect to that gene.

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So there's hollow-stemmed F2s floating around with the hemp chemotype? :icon_dizzy:

 

[Chemotype]

No.

What its saying is that the chemotype of the plant is determined by the occurance at the B locus, of two codominant alleles, BD and BT. What that means is if you take chemotype I (say White Widow) and breed it with chemotype III (hemp) you end up with Chemotype II in the F1. Then if you inbreed the F1, the F2 will exhibit all three chemotypes. This coud be usefull in the medical field because a breeder can increase CBD content over THC for patients with pain and anxiety and greater THC for cancer patients, etc. This is only controlling the THC/CBD ratio though, not the other cannabinoids as far as the study shows. And the %THC greater than the %CBD, or %CBD greater than %THC, are polygenic or epistatic most likely.

There are two additional chemotypes occasionally reported Chemotype IV had CBG as the predominant cannabinoid, but also CBD was present (Fournier et al. 1987); chemotype V was proposed by Mandolino and Carboni (2004) to classify material with undetectable amounts of any cannabinoids, qualitatively described by some authors (Virovets 1998).

Hope that clears it up?

 

[been]

Ah, you scared me for a second. :rofl

 

[theherbalizor]

Very good stuff that. But I think it needs to be said that pretty much all ch2/3 have been completly breed out of drug cultivars. To find something leaning toward chemo 2 would be rare, and to find a chemo 3 would be a 100000 in one chance at best I should say.

I would love a chem 2 cultivar. Perhaps a landrace (true) ghan / pakistan / uzbeki etc

 

[Chemotype]

Very good stuff that. But I think it needs to be said that pretty much all ch2/3 have been completly breed out of drug cultivars. To find something leaning toward chemo 2 would be rare, and to find a chemo 3 would be a 100000 in one chance at best I should say.

I would love a chem 2 cultivar. Perhaps a landrace (true) ghan / pakistan / uzbeki etc

Yeah too bad not many landraces are available.

You could always breed a hemp cultivar (Chemotype III)with your favorite strain (Chemotype I ) and make some good selections, those would all be Chemotype II, according to the paper. Finding the right hemp cultivar would be a journey though. :icon_dizzy:

 

[SnowCap]

Interesting, but how would one breed solely on this knowledge? If we do have say a Chemotype I and a Chemotype II, what is to say crossing them will produce a variance from the 2. Plants like humans contain DNA and is stored in different locations. There is Nucleic acid DNA, Mitochondrian DNA, and in plants Chloroplast DNA of known sources and possible locations of genetic knowledge able to produce and develop offspring. Just like mammals and plants a male crossing with a female does not produce an exact 50/50 % of both parents. So take this to think about, have you ever seen a really beautiful woman and then seen her parents and find that they are both either ugly or nothing like their offspring? This can also be the case when your thinking about breeding with plants. The 2 ugly ducklings can produce beautiful children...

I will now go back to my cave... Take care and happy growing. I like this type of conversation as its needs to happen more often to truly understand the many facets of cannabis.

SnowCap

 

[been]

Better not let anyone find out you're breeding with hemp.

 

[Chemotype]

Interesting, but how would one breed solely on this knowledge? If we do have say a Chemotype I and a Chemotype II, what is to say crossing them will produce a variance from the 2. Plants like humans contain DNA and is stored in different locations. There is Nucleic acid DNA, Mitochondrian DNA, and in plants Chloroplast DNA of known sources and possible locations of genetic knowledge able to produce and develop offspring. Just like mammals and plants a male crossing with a female does not produce an exact 50/50 % of both parents.

SnowCap

In the case that a trait is controlled by two codominant alleles and two homozygous parents of separate types (chemotype I and III) are crossed all progeny will be heterozygous at those alleles and thus all progeny are chemotype II, a 50/50 of the two parents. Now, since these are all heterozygous at those alleles when you inbreed them you will get (with a large enough population) a text book example of a 1:2:1 genotypic ratio of all chemotypes 1-chemotype I: 2-chemotype II: 1-chemotype III. Thats how to breed based solely on this, if you are breeding for chemotype alone. :whew

But to produce a great chemotype II plant would be work. Hemp might produce a horrible high no matter what its crosses with. I don't know of anyone who has tried it.

 

[pot4pain]

Great thread, thanks for sharing the info!

 

[jvafResearch]

Hello!
I'm a student from Argentina and I intent to publish an article on Cannabidiol use in psychiatry.
I need some guidance, because I've been reading about Cannabis sativa, yet I have difficulty getting the full picture. Do you have any information (papers) on the following subjects?:
1) main alkaloids found in all strains (%)
2) chemotype distribution (do you have the full text of the Article you cited about the 3 chemotypes)
3) difference in the distribution of alkaloids in female and male plants and within the plant (seeds, flower, leaves, etc.)
I would really appreciate any help
Thank you!:help:

 

[Chemotype]

Hello!
I'm a student from Argentina and I intent to publish an article on Cannabidiol use in psychiatry.
I need some guidance, because I've been reading about Cannabis sativa, yet I have difficulty getting the full picture. Do you have any information (papers) on the following subjects?:
1) main alkaloids found in all strains (%)
2) chemotype distribution (do you have the full text of the Article you cited about the 3 chemotypes)
3) difference in the distribution of alkaloids in female and male plants and within the plant (seeds, flower, leaves, etc.)
I would really appreciate any help
Thank you!:help:

Sure. I have a lot of papers to share if it is not too late. sorry I haven't been on forever. Send me your email in a private message and i'll send them.

 

[bioguy]

My 2 cents.

From....The Inheritance of Chemical Phenotype in Cannabis sativa L.
- Confirms the 1-2-1 ratio was achieved from selfing the F1
- The 00.45.1 clone was an exception, having both CBD and THC (Chemo 2) in similar amounts.
- In many cases it was possible to collect sufficient viable seed to constitute a first generation inbred line (S1), which was completely female showing the same chemotype as the parental clone. The 00.45.1 S1, however, segregated into pure CBD, mixed CBD THC, and pure THC individuals.

This confirms that C1 + C3 = C2 and C2 + C2 = C1, C2, C3

This paper is over 10 years old. I wonder if this knowledge has made it into the breeding world. Might it have lead to the proliferation of CBD strains that appeared 10 or so years ago?

I see 2 uses for this info.
1) Making CBD strains (obviously)
2) Using hemp to re-introduce genes to the Chemotype 1....fine cannabis is often the result of double recessive genes. 100's of amazing traits may be lost in the hemp genome that we don't see because they are hidden under dominant genes.

I also see a couple problems.
The research was conducted on selfed F1 from "double selfed S2 parents". Selfing an F1 homogenizes the alleles. I expect you would see a divergence from the 1-2-1 ratio if this was done with "regular" plants. Of course it could be done with true breeding hybrids but we are finding they are generally not as spectacular as our modern "variable" plants (would you rather have a bag of chem dawg seeds or skunk #1).

The next problem I see is what happens when you cross the newly created chemo 2 with a chemo 1. In this case 1/8 of the plants would contain hemp genes - more if non selfed plants were used. This would be no prob in a lab setting but if these seeds were released to the public amateur breeders would inevitably cross it to all types of stuff (spreading the hemp genes). I am not positive this would be bad...it may lead to vigor, resistance or other new traits...it could also be a long ugly road to travel. If the CBD strains on the market were created this way then it may have already happened. Since this technology is based on selfed plants I suspect this is NOT the way these strains were created (this s speculation based on he taboo of selfed plants among professional breeders).

P.S. I love evolutionary biology. Prohibition of cannabis has caused it to be the last frontier of evo/devo.

 

[xX Kid Twist Xx]

great post

I also see a couple problems.
The research was conducted on selfed F1 from "double selfed S2 parents". Selfing an F1 homogenizes the alleles. I expect you would see a divergence from the 1-2-1 ratio if this was done with "regular" plants. Of course it could be done with true breeding hybrids but we are finding they are generally not as spectacular as our modern "variable" plants (would you rather have a bag of chem dawg seeds or skunk #1).

"selfging an F1 homogenizes the alleles." this is what i was thinking because the dominate alleles would overlap. Im wondering if the plant would lose anything that may be held in the resesive allele, or if i just kept selfing a S1 plant would all the plants just be the same as what can be found in the s1 breeding?

 

[bioguy]

"selfging an F1 homogenizes the alleles." this is what i was thinking because the dominate alleles would overlap. Im wondering if the plant would lose anything that may be held in the resesive allele, or if i just kept selfing a S1 plant would all the plants just be the same as what can be found in the s1 breeding?

Thanks

The way I understand it doubling of dom alleles should not cause any issues because they are expressed in both cases (Aa and AA) but doubling the recessive can eliminate or fix the allele (Aa => aa or AA). This may be why selfed plants are not always identical and why none of the phenotypes are desirable. If so selfing again would not restore the Aa (neither would any amount of selfing) but crossing the two pheno's would every time (at least in some perfect mathematical world that we don't live in).

I believe the real problem lies in co-dominance and multi-gene interactions that fall apart during the selfing.

The final thing that comes to mind is environment based phenotype determination that occurs in the first few weeks of the plants life. A clone only strain with an amazing trait may be expressing the trait due to something that happened in its youth that is not always replicated. It could have been pot size, nutrient levels, stress, lighting wavelength or a combo of all. I have no proof for this but.... Sativa growers have been flowering plants from seed under 12/12 in small pots to force smaller phenotypes for decades AND landrace genetics often lack luster when grown away from their native soil. So I ask, what other traits might be manipulated? Might terrible soil (or perfect soil) trigger the expression of a gene responsible for a specific terpene?