Chemotaxonomy of Cannabis I

Chemotaxonomy of Cannabis I. Crossbreeding between Cannabis sativa and C. ruderalis, with Analysis of Cannabinoid Conten...

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Chemotaxonomy of Cannabis I. Crossbreeding between Cannabis sativa and C. ruderalis, with Analysis of Cannabinoid Content Author(s): John A. Beutler and Ara H. Der Marderosian Source: Economic Botany, Vol. 32, No. 4 (Oct. - Dec., 1978), pp. 387-394 Published by: Springer on behalf of New York Botanical Garden Press Stable URL: http://www.jstor.org/stable/4253980 . Accessed: 30/12/2010 01:27 Your use of the JSTOR archive indicates your acceptance of JSTOR's Terms and Conditions of Use, available at . http://www.jstor.org/page/info/about/policies/terms.jsp. JSTOR's Terms and Conditions of Use provides, in part, that unless you have obtained prior permission, you may not download an entire issue of a journal or multiple copies of articles, and you may use content in the JSTOR archive only for your personal, non-commercial use. Please contact the publisher regarding any further use of this work. Publisher contact information may be obtained at . http://www.jstor.org/action/showPublisher?publisherCode=nybg. . Each copy of any part of a JSTOR transmission must contain the same copyright notice that appears on the screen or printed page of such transmission. JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact [email protected].

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CHEMOTAXONOMY OF CANNABIS I. CROSSBREEDING BETWEEN CANNABIS SATIVA AND C. RUDERALIS, WITH ANALYSIS OF CANNABINOID CONTENT JOHN A. BEUTLER1 AND ARA H. DER MARDEROSIAN A controlledcross between Cannabissativa L. and C. ruderalisJanisch.gave progenyintermediatein both cannabinoidcontent and morphology.The progeny fell into two distinctpopulations,those whose tetrahydrocannabinol (THC)content was closer to the C. sativa parent(greaterthan 60%of total cannabinoids) and those whose THC content was closer to the C. ruderalisparent (less than 40%0 of total cannabinoids).The lower THC group was twice as frequentas the othergroup.Earlinessof flowering,numberof flowers, and heightcharacteristics were intermediatebetween the parents.

The taxonomy of Cannabis has assumed importancewith the spread of marijuana as a drug of abuse, because most state and federal laws are written in terms of only one species, Cannabis sativa L. The supposed existence of more than one species in the genus has caused considerable legal difficulty. At least one article (Fullerton & Kurzman, 1974) has been written providingan arsenal of informationthat has proved successful in achieving acquitals in marijuana possession cases. Generallythe Prosecutionis forced to prove which species has been confiscated to determineif the law has actually been violated. Much work has been done from a morphologicalpoint of view on Cannabis taxonomy. The history of the originalbotanical literaturehas been reviewed in detail (Emboden, 1974; Schultes et al., 1974). A large variety of freshly grown specimens have been examined, both for morphology(Small & Cronquist, 1976) and chemistry (Small et al., 1975; Fetterman et al., 1971). Three species have been delineated by Schultes et al. (1974), namely C. sativa L., C. indica Lam. and C. ruderalis Janisch. They have published a key for the differentiationof these three species based on height, branching, seed coat marbling,and seed attachmentand its abscission layer. Other investigators have held to the traditionalmonotypic concept (Small & Cronquist, 1976), holding that the wide variationsin such charactersand others are simply due to the inherent plasticity of the species. Most phytochemical studies have revealed Inomajordifferences in the content and quality of cannabinoids (other than the ratio of cannabidiolto tetrahydrocannabinol)that could serve to differentiatespecies. Other chemical markersof taxonomic significance have not been found. Both chemical and morphologicalstudies have been essentially static studies of a genetically dynamic organism,with little experimentalattentiongiven to the genetics on which the taxonomic charactersare based. In an attempt to clarify the taxonomic situation, and to elucidate the genetics of cannabinoidproduction, we have carried out preliminarycross-breedingexperiments between Cannabis sativa L. and Cannabis ruderalis Janisch. under

greenhouseconditionswith the plants in reproductiveisolationfromother strains. Such a cross has been noted in the wild (R. E. Schultes, pers. comm., 1977)but was not included in the work of Small (1972) who intercrossed 38 strains of Cannabis, and found all strains to be interfertile. 1 The PhiladelphiaCollege of Pharmacyand Science, Departmentof Biological Sciences, Philadelphia, PA 19104. Submittedin partialfulfillmentof the degree of Masterof Science, November28, 1977. Received for publicationDecember 14, 1977;accepted for publicationJanuary18, 1978.

Economic Botany, 32(4), 1978, pp. 387-394

? 1979,by the New York BotanicalGarden,Bronx, NY 10458

CANNABICHROMENOIC ACID

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OH MEVALONATE

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CANNABIDIOLIC

MEVALXNATE

OH

GERANIOL

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ACETATE MALONATE

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ACID

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TETRAHYDROCANNABINOLIC

OCH, CANNABIGEROLIC

ACID

ACID

MONOMETHYL ETHER

FIG. 1. Biosynthesisof cannabinoids(after Shoyamaet al., 1974).

Recent advances in the understandingof cannabinoidbiosynthesis have made possible more meaningfulexperimentswith the plant. Shoyamaet al. (1974)have elegantlyelucidatedthe biosyntheticpathwayto the cannabinoidacids from mevalonate, acetate, and malonate.These are well recognizedas the true biosynthetic products of the plant (Fig. 1). Many of the minor cannabinoids isolated have come to be seen as degradationproducts of the naturalcannabinoidson storage, exposure to light, curing, and other processing. Small & Cronquist's work (1976) and the work of Fettermanet al. in Mississippi (1971) have strengthened the view that THC-acid production is more dependent on the genome of the plant than on environmentalfactors. Our breedingexperimentswere designed to take a closer look at the breeding behavior of the plant with respect to cannabinoidproduction, measuredby gas chromatographictechniques, and backed up by mass spectralidentificationof the gas chromatographicpeaks as cannabinoids. MATERIALS AND METHODS

Seed samples.-JBC-2 was obtained from the CentralSiberianBotanical Garden, Novosibirsk, USSR, and labelled Cannabisruderalis. This is possibly identical to the C. ruderalisin Small & Beckstead (1973, p. 164, Table 5). It produced small(less than2 ft) quick-floweringplantswith low THC content (less than0.2%). The seeds were marbledand droppedoff at maturity, and the "fleshy carunclelike growth at the base" was evident, though not obviously so. JBC-3 was an alledgedly Mexican strain of C. sativa which reached 6-7 ft in height when given adequate root space, did not flower until it had reached this height, and contained a relatively high amount of THC (between 1.0 and 2.0WO). Seeds were plain and indehiscent at maturity. Despite the lack of an authentic originfor this strain, it conforms to all published criteriafor C. sativa. Growingconditions.-Seeds were sown in rows in flats containingtwo parts of topsoil to one part peat moss. The greenhouse was kept between 700and 80?F. When several inches tall, the seedlings were transplantedto large plastic tubs 16 inches in diameter and eight inches deep, a size that was found to minimally restrictgrowth. Smallerpots were not used because this producedsmallerplants of C. sativa, disguising useful differences in growth and flowering behavior.

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ECONOMICBOTANY

Plants were watered twice daily by an automaticcapillarywateringsystem, and positioned to receive full sun in the greenhouse. The time of sowing was not strictly controlled with regardto day-length,however the quickness of floweringwas constant within the plants of each strainused in the cross. The Mexican strain (JBC-3) has shown erratic floweringbehavior when grown out of step with the normal seasonal variationsin day-length. The Cannabis ruderalis (JBC-2) flowered promptly when sown at any point from November to May. Convenience dictated that plants of the two strains not be started at the same time, due to the difference in time requiredfor flower production. Plants were harvested when mature;i.e., for males, after the pollen had been substantiallyshed; and for females, after sufficient ripe seed had been collected for furtherbreedingwork. All samples analyzed were freeze-driedand stored in the dark in sealed plastic bags at room temperature. Samplingprotocols varied, especially for the Mexican strain, but all parts of the same plant contained identical cannabinoidprofiles if they contained any at all. Roots and woody stems did not contain cannabinoids,and leaves contained less than the floweringtops. All C. ruderalis plants were analyzed as the whole freeze-driedplant. Whereseveral very small individualswere concerned, several of the same sex and age were combined into the same sample. Gas chromatography.-The procedure used was based on that of Lerner (1969). One g of plant materialwas shaken with 40 ml of chloroform at room temperaturefor one hour in a stoppered Erlenmeyer flask. The solution was filtered, the plant materialrinsed with a few ml of chloroform,and the combined solution evaporated under reduced pressure. This residue was taken up first in 2.0 ml of chloroform,and then 2.0 ml of the internalstandardsolution (5.0 mg/ml androstene-3,17-dionein methanol)was added. This solution was storedin screwcapped vials with teflon inserts in the caps at freezer temperatures.Caps without teflon inserts were leached by both methanol and chloroform. Dioctyl phthalate from the cap leachates was found to have a relative retentiontime of 0.45, which without mass spectral analysis could be confused with A-8-THC. Samplesolutions were injectedon a 3%OV-17on 100/120Gas ChromQ column (Supelco, Inc.) 6 ft long, 4 mm i.d., installed in an HCl Scientific gas chromatograph, or Varian model 3700 gas chromatograph,both with flame ionization detection. Injectortemperaturewas 255?C,columntemperatureisothermalat 220?C, carriergas flow (He) 120 ml/min.Typically one microliterof sample solution was injected. Peak areas were determinedby multiplyingheight times half-heightwidth. This was compared to the area of the internal standardpeak and corrected for the amountof plant materialtaken, along with the response factor of each compound. It should be noted that this procedure does not differentiatebetween cannabidiol (CBD) and cannabichromene(CBC) (RRT-0.36)(Turneret al., 1975). To ascertain the identity of this peak, gas chromatographyat 180?Con a 3 % OV101 column was performed.The results of this separationwere used to get the ratio of CBD to CBC in the combined peak on OV-17. RESULTS AND DISCUSSION

Chemistry.-The results of glc analysis are presented in Figure 2 as total percent cannabinoidson a dry weight basis versus A9-THCas percent of total cannabinoids(CBD, CBC, Y9-THC).This method of expressingcannabinoidcontent gives a comparisonof overallproductionof cannabinoids,as well as an indication of how much of this cannabinoidproductionis A9-THC.The percentageof CBC

BEUTLER & DER MARDEROSIAN: CANNABIS

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