Characterization of 15 STR cannabis loci: Nomenclature proposal and SNPSTR haplotypes.
ABSTRACT The standardization of methods for individualizing Cannabis sativa plants could offer new possibilities in the investigation of its illegal trade. Here we present the first nomenclature proposal for 15 cannabis STRs, which allows an initial standardization for performing comparisons between laboratories and generating genotype databases. Several alleles of the 15 STR loci have been sequenced. This has revealed that not all the STR loci are equally suitable for the individualization purposes. Moreover, several nucleotide variations have been detected both inside the repeat structure and/or in the flanking region. All the different SNPSTR haplotypes are presented and compared with the previous sequence raw data of the 15 STR loci. The SNPSTR data could considerably increase the informative value of the STRs, which could be very useful in complex cases.
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ABSTRACT: Short tandem repeat (STR) markers are the DNA marker of choice in forensic analysis of human DNA. Here we extend the application of STR markers to Cannabis sativa and demonstrate their potential for forensic investigations. Ninety-three individual cannabis plants, representing drug and fibre accessions of widespread origin were profiled with five STR makers. A total of 79 alleles were detected across the five loci. All but four individuals from a single drug-type accession had a unique multilocus genotype. An analysis of molecular variance (AMOVA) revealed significant genetic variation among accessions, with an average of 25% genetic differentiation. By contrast, only 6% genetic difference was detected between drug and fibre crop accessions and it was not possible to unequivocally assign plants as either drug or fibre type. However, our results suggest that drug strains may typically possess lower genetic diversity than fibre strains, which may ultimately provide a means of genetic delineation. Our findings demonstrate the promise of cannabis STR markers to provide information on: (1) agronomic type, (2) the geographical origin of drug seizures, and (3) evidence of conspiracy in production of clonally propagated drug crops.Forensic Science International 02/2003; 131(1):65-74. · 2.31 Impact Factor
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ABSTRACT: We report on the first short tandem repeat (STR) locus to be isolated from the plant Cannabis sativa. The STR locus, isolated by a hybrid-capture enrichment procedure, was found to contain a simple sequence repeat motif of 6 bp. This 6 bp repeat motif showed no variation in repeat length but with minor variations in repeat unit sequences. The data show the locus to be highly polymorphic with the number of repeat units ranging from 3 to 40 in 108 screened samples. The observed heterozygosity was approximately 87.04%. The forward and reverse primers (CS1F and CS1R) produced no PCR products in cross-reaction study from 20 species of plants, including highly related species such as Humulus japonicus and Nicotiana tabacum. This hexanucleotide repeat DNA locus could be used to identify cannabis samples and predict their genetic relationship as the test is specific to C. sativa and is highly reproducible.Forensic Science International 02/2003; 131(1):53-8. · 2.31 Impact Factor
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ABSTRACT: The purpose of this review is to summarize the status of DNA-based methods for the identification and individualization of marijuana. In forensics, both identification of a substance as marijuana and the subsequent individualization of a sample may be desired for casework. Marijuana identification methods in the United States primarily include biochemical tests and, less frequently, DNA-based tests. Under special circumstances, DNA-based tests can be useful. For example, if the quantity of seized marijuana is extremely small and/or biochemical tests do not detect any D9-tetrahydrocannabinol (THC), DNA identification of plant material as Cannabis is still possible. This circumstance can arise when seeds, trace residue, tiny leaf fragments, or fine roots need to be analyzed. Methods for the individualization of marijuana include amplified fragment length polymorphism (AFLP), random amplified polymorphic DNA (RAPD), and short tandem repeat (STR) techniques that link an evidentiary sample to a source. Marijuana growers propagate their plants either by seed or by cloning. Seed-generated marijuana plants are expected to have unique DNA profiles analogous to a human population. Cloned marijuana plants, however, exhibit identical DNA profiles that allow for tracking of plant material derived from a common genetic lineage. The authors have validated the AFLP method for marijuana samples and are constructing a comparative database of marijuana seizure samples to estimate the expected frequency of a DNA profile match between unrelated plants. Continued development of DNA-based methods for plants can be useful for marijuana and other types of plant evidence in forensics.Croatian Medical Journal 07/2003; 44(3):315-21. · 1.25 Impact Factor