Interesting Article on Inheritence of Chemical Phenotype

[Grat3fulh3ad]

http://www.genetics.org/cgi/content/full/163/1/335

 

[Grat3fulh3ad]

Interesting excerpt.....

DNA markers in Cannabis

Today, the concept of Cannabis as a monotypic genus is widely accepted; taxonomical, morphological, and biometrical studies confirm the continuity of its gene pool despite the extremely high variation found within and between populations (SMALL et al. 1976 ?; DE MEIJER and KEIZER 1996 ?). In the last few years, the existence of just a single species within the genus has been confirmed by molecular marker studies that show a limited segregation of the different groups within the genus Cannabis and an extremely high degree of polymorphism, estimated to be of the same magnitude within and between populations (FAETI et al. 1996 ?; FORAPANI et al. 2001 ?). Within some of the best-known hemp cultivars, e.g., Carmagnola, the degree of polymorphism was estimated by randomly amplified polymorphic DNA (RAPD) markers to involve ?80% of the markers scored, and the data suggested a huge reservoir of variation within even the most selected Cannabis strains considered during the study. Finally, within the dioecious populations, the presence of a high number of male-specific markers, presumably associated with the Y chromosome, was found by RAPD and amplified fragment length polymorphism analysis (MANDOLINO et al. 1999 ?, MANDOLINO et al. 2002 ?; FLACHOWSKY et al. 2001 ?).

 

[Grat3fulh3ad]

Another Excerpt....

Constitution of inbred lines:

All parentals used in this study were doubly inbred plants (S2's) obtained through the self-fertilization of selected female clones from the Cannabis collection of HortaPharm B.V., The Netherlands. The original plants had either CBD or THC as the predominant cannabinoid. The 00.45.1 clone was an exception, having both CBD and THC in similar amounts. The clones were obtained through in vivo propagation of lateral branches. An individual from each clone was partially sex reversed according to the procedure described by MOHAN RAM and SETT 1982 ? and allowed to self-pollinate in isolation. In many cases it was possible to collect sufficient viable seed to constitute a first-generation inbred line (S1), which was completely female and 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. Here, further inbreeding was restricted to the pure CBD plants. An S2 generation was produced from some of the S1 plants, using the same procedure described above. The work focused on six S2 lines, briefly described in Table 1. A leaf sample was collected for DNA analysis from 10 to 20 plants per S2.

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Table 1. Characteristics of the parental inbred lines

Production of F1's and F2's:?Seven individual plants belonging to the six S2 lines with contrasting chemotypes were chosen to produce hybrid F1's. The individual female plants used as pollen parents were partially sex reversed and placed in isolation cabinets with the seed parent plants. The crosses performed are summarized in Table 2.

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Table 2. Pedigrees and codes of the studied progenies

The next season, a variable number of individual plants of the four different F1's were grown and their chemotype was determined. Again, leaf samples from 5–20 plants belonging to the four F1's were taken for molecular analysis. Ten F1 plants (3 plants from cross 99.3, 3 from 99.4, 1 from 99.5, and 3 from 99.6; Table 2) were again treated to obtain partial sex reversion, isolated, and allowed to set F2 seed. The seeds were sown and a variable number of F2 mature plants, ranging from 35 to 118, were evaluated for chemotype; leaf samples were again collected for DNA analysis. During three seasons (1998–2000), the complete cycle from the parental S2 inbred lines to the different F2 progenies was accomplished under similar greenhouse conditions and strict isolation. Confirmation of the genetic femaleness of all the plants was based on the absence of any male-specific marker.

 

[Grat3fulh3ad]

one more....

**Aim of the work

This study aims to clarify the inheritance of cannabinoid chemotype, by isolating pure CBD and pure THC inbred lines. A simple inheritance model was proposed after making crosses between the chemotypically contrasting lines and examining a number of F1 and F2 progenies. An RAPD analysis of the parental lines and their offspring was performed and a number of chemotype-associated markers were described.

 

[Grat3fulh3ad]

Last one....

The uniformity of F1 chemotypes and the F2 segregation ratios demonstrate the presence of a single locus, which is referred to as B, showing simple Mendelian inheritance of the two alleles, BD and BT, evidenced by this study. The model proposes that a pure CBD plant has a BD/BD genotype at the B locus, while a pure THC plant has a BT/BT genotype. F1 and 50% of the F2 plants are therefore heterozygous BD/BT, with the two alleles being codominant and therefore simultaneously expressed in the hybrids. The hypothesis of two alleles at one locus was accepted by 2 tests for all the F2's examined (Table 4). This model agrees with the assumption of a monogenic inheritance as expressed by BECU et al. 1998 .

 

[Grat3fulh3ad]

Today, the concept of Cannabis as a monotypic genus is widely accepted; taxonomical, morphological, and biometrical studies confirm the continuity of its gene pool despite the extremely high variation found within and between populations (SMALL et al. 1976 ?; DE MEIJER and KEIZER 1996 ?). In the last few years, the existence of just a single species within the genus has been confirmed by molecular marker studies that show a limited segregation of the different groups within the genus Cannabis and an extremely high degree of polymorphism, estimated to be of the same magnitude within and between populations

I found this to be a very interesting assertion... any comments?

 

[Grat3fulh3ad]

I also found the researcher's method of IBL creation odd and interesting...

 

[Sleepy]

good info...

its good to think sometimes.

 

[Guest]

Havent finished reading, and im gettin sleepy, but thanks alot head

Great read so far, and i got something to chew on for a while now

 

[Mr GreenJeans]

Great thread GH!
Been a long time since I exercised my botany, but what strikes me unusual is the high degree of variability / polymorphism. Historically a genus with extreme polymorphism dies out after a possibly long but finite time. If I had to guess the relationship with man is responsible for spreading the seed widely enough to survive. But then again I'm definitely not a paleobotanist. so what do I know!

Very interesting study!

 

[gnosis]

I found this to be a very interesting assertion... any comments?

Speaking of the same subject with a friend, lately, i -certainly wrongly, though they are all kinds of wrong- compared this to human genus. As: noticable diferences due to adaptability, but not races per se.

 

[Grat3fulh3ad]

"monotypic" refers to a taxon that contains only one immediately subordinate taxon.[1] For example, a monotypic genus has only one species.

 

[guineapig]

Then again, a species with a high degree of polymorphism might be better able to
adapt to the infinite diversity of habitats, insect predation, and weather patterns
throughout the world......but really, seeing how this plant is so useful and has been
used for so so many applications during the past 10,000 years, i would bet that
humans are partially responsible......

I love this article too Grat3fulh3ad!!!!

A few months back i got some requests to break this article down from some
people on another website so i gave the following response:

Hello scientists!!

I decoded this "Inheritance of Chemical Phenotype" article awhile back and so if you don't want to wade through the scientific jargon:

"So these people want to find out exactly how the drug characteristics of Cannabis plants are inherited. Some people thought that the qualities of the "high" (also known as the ratios of THC to CBD) were geographically dependent. This turned out not to be true. So they got some plants from some place called HortaPharm in the Netherlands who carried one strain that was primarily CBD in cannabinoid content and another that was primarily THC and crossed them. The results were a classic 1:2:1 ratio of CBD:a CBD/THC intermediate:THC. Boy was that good news for them. They then proposed that there is a single locus that codes for the drug chemotype in each plant. They then propose that THC and CBD might be on separate loci that are just very close to each other on the chromosome and that would also explain the classic segregation ratio of 1:2:1. But then they refute this possibility. Then they go home and smoke a joint, publish the paper, and list it on their CV (resume)."




kind regards from guineapig

 

[Grat3fulh3ad]

Very good synopsis for the average joe, GP...
Here is a bit more in-depth synopsis, centering on points I find interesting....

Chemotypical diversity in cannabis:
Cannabis produces turpenolic substances known as cannabinoids in its glandular trichomes.
The most common cannabinoids are CBD and THC.
Within the population of cannabis there are four main chemotypes.
1. mostly THC
2. mostly CBD
3. CBD and THC
4. mostly CBG (CBG is the precursor to THC and CBD)

Chemotype inheritance:
Though Environmental factors influence the amount of cannabinoids present in different growth phases, the patern of chemotype distribution indicates strongly that the cannabinoid profile is genetic.

DNA markers in cannabis:
The concept of cannabis as a single species plant is widely accepted.
Studies have confirmed the continuity of the genepool, despite all the variations.
The existance of a single species has been confirmed by molecular marker studies.
There are a high number of male-specific genetic markers.


The experiment:
Plants were selected that were THC dominant and CBD dominant, and each plant was selfed for two generations to create IBL parents.
TCH and CBD IBLs were crossed, the results were uniformly THC/CBD plants.
These F1 plants which produced both THC and CBD were then selfed to create f2s.
The F2s showed the classic Tripartite paterns. 1:2:1 CBD:CBD/THC:THC.

The Result:
This shows a single Locus that determines chemical phenotype.

 

[CannaBuilding]

Alright i read it, veyr interesting

Just a couple of questions the plants that lean more the CBD are indica dominant i presume? the THC dominant are sativa? Im just assuming, cause i know when THC breaks down to CBD you get more of a couchlock feeling hence indica sort of effect

Correct me if im wrong

 

[Grat3fulh3ad]

Alright i read it, veyr interesting

Just a couple of questions the plants that lean more the CBD are indica dominant i presume? the THC dominant are sativa? Im just assuming, cause i know when THC breaks down to CBD you get more of a couchlock feeling hence indica sort of effect

Correct me if im wrong

that seems correct to me
Although within the context of the article they basicly call an indica, a CBD dominant sativa.

 

[SativaBelieva]

So CBD-dom/THC-dom hybrids will be the strongest?

 

[Grat3fulh3ad]

So CBD-dom/THC-dom hybrids will be the strongest?

They way I see it, and read the charts, Potency Potentially increases dramaticly in the f1 and f2 generaton. This is where the importance of very careful selection comes in Making sure that only the most desirable traits get passed to subsequent generations.

 

[Grat3fulh3ad]

http://www.genetics.org/cgi/content/full/163/1/335/F2
Figure 2 which shows the Potency of the original parents and of the F1 offspring.

 

[Grat3fulh3ad]

http://www.genetics.org/cgi/content/full/163/1/335/F3
Figure 3 which shows potency and chemotype distribution of the f2 generation, along with that of the parents and grandparents.