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Four crosses were made between inbred Cannabis sativa plants with pure cannabidiol (CBD) and pure [DELTA]-9-tetrahydrocannabinol (THC) chemotypes. All the plants belonging to the [F.sub.1]'S were analyzed by gas chromatography for cannabinoid composition and constantly found to have a mixed CBD-THC chemotype. Ten individual [F.sub.1] plants were self-fertilized, and 10 inbred [F.sub.2] offspring were collected and analyzed. In all cases, a segregation of the three chemotypes (pure CBD, mixed CBD-THC, and pure THC) fitting a 1:2:1 proportion was observed. The CBD/THC ratio was found to be significantly progeny specific and transmitted from each [F.sub.1] to the [F.sub.2]'s derived from it. A model involving one locus, B, with two alleles, [B.sub.D] and [B.sub.T], is proposed, with the two alleles being codominant. The mixed chemotypes are interpreted as due to the genotype [B.sub.D]/[B.sub.T] at the B locus, while the pure-chemotype plants are due to homozygosity at the B locus (either [B.sub.D]/[B.sub.D] or [B.sub.T]/[B.sub.T]). It is suggested that such codominance is due to the codification by the two alleles for different isoforms of the same synthase, having different specificity for the conversion of the common precursor cannabigerol into CBD or THC, respectively. The [F.sub.2] segregating groups were used in a bulk segregant analysis of the pooled DNAs for screening RAPD primers; three chemotype-associated markers are described, one of which has been transformed in a sequence-characterized amplified region (SCAR) marker and shows tight linkage to the chemotype and codominance.

The objective was to study the genetic structure and degree of variability of hemp (Cannabis sativa L.) varieties. Six varieties of hemp were analyzed by random amplified polymorphic DNA (RAPD) analysis, using 10 plants per variety. The varieties were a dioecious landrace, a dioecious selection from it, a cross-bred cultivar, a monoecious variety, a drug strain, and an inbred female line. The genetic complexity of each cultivar was investigated by determining the number of bands produced by the primers used, the number of fixed and polymorphic loci, the average allele frequency, and the heterozygosity. A good correlation was found between these parameters and the genetic origin and breeding strategy of each variety. The average polymorphism over all varieties and loci was 97.1%; the single cultivar polymorphism ranged from 31.1 to 85.5%. Heterozygosity ranged from 0.05 (inbred female line) to 0.26 (cross-bred Fibranova). The average heterozygosity calculated over all 102 loci and all plants studied was 0.29. The Fst (Wright's fixation index) value calculated for all loci was 0.48, and only 33.3% of the scored loci had higher values and can be considered informative for cultivar identification. A Fisher's test based on allele frequencies suggested complete differentiation among all varieties, with the exception of the Italian dioecious varieties Carmagnola and CS, for which no discriminating alleles were found. The correlations among the molecular data and the genetic structure of the different cultivars and the consequences in relation to variety discrimination in hemp are discussed., HEMP is a traditional crop in Europe and Asia. It belongs to the Cannabaceae family, which comprises two genera: Cannabis and Humulus (hops). Despite hemp's past importance for both the [...]

Abstract Background Since its discovery more than 100 years ago, potato (Solanum tuberosum) tuber cold-induced sweetening (CIS) has been extensively investigated. Several carbohydrate-associated genes would seem to be involved in the process. However, many uncertainties still exist, as the relative contribution of each gene to the process is often unclear, possibly as the consequence of the heterogeneity of experimental systems. Some enzymes associated with CIS, such as β-amylases and invertases, have still to be identified at a sequence level. In addition, little is known about the early events that trigger CIS and on the involvement/association with CIS of genes different from carbohydrate-associated genes. Many of these uncertainties could be resolved by profiling experiments, but no GeneChip is available for the potato, and the production of the potato cDNA spotted array (TIGR) has recently been discontinued. In order to obtain an overall picture of early transcriptional events associated with CIS, we investigated whether the commercially-available tomato Affymetrix GeneChip could be used to identify which potato cold-responsive gene family members should be further studied in detail by Real-Time (RT)-PCR (qPCR). Results A tomato-potato Global Match File was generated for the interpretation of various aspects of the heterologous dataset, including the retrieval of best matching potato counterparts and annotation, and the establishment of a core set of highly homologous genes. Several cold-responsive genes were identified, and their expression pattern was studied in detail by qPCR over 26 days. We detected biphasic behaviour of mRNA accumulation for carbohydrate-associated genes and our combined GeneChip-qPCR data identified, at a sequence level, enzymatic activities such as β-amylases and invertases previously reported as being involved in CIS. The GeneChip data also unveiled important processes accompanying CIS, such as the induction of redox- and ethylene-associated genes. Conclusion Our Global Match File strategy proved critical for accurately interpretating heterologous datasets, and suggests that similar approaches may be fruitful for other species. Transcript profiling of early events associated with CIS revealed a complex network of events involving sugars, redox and hormone signalling which may be either linked serially or act in parallel. The identification, at a sequence level, of various enzymes long known as having a role in CIS provides molecular tools for further understanding the phenomenon.

Four crosses were made between Cannabis plants with "pure" CBD and THC chemotypes. The F1 plants were self-fertilised to produce F2s. Chemical distributions were analysed by gas-chromatography. A segregation analysis of the different F2 progenies obtained showed that chemotype, estimated as CBD/THC kratio, behaves as a qualitative character, and a model for a single locus B, with two co-dominant alleles, BD and BT is described. The CBD/THC ratios in the F1 offsprings were found to be significantly different in the heterozygous plants from the different pedigrees. The amount of CBD plus THC in the same pedigrees was also described. Heterosis was found to be a common feature, but not a general one, of cannabinoid accumlation in the F1s. Distribution of the values of cannibinoid content in classes was found to be normal. RAPD markers linked to the segregating chemotypes ("pure" CBD and "pure" THC) were identified by bulk segregant analysis, and the degree of the linkage of these markers with the chemotype was described. [ABSTRACT FROM PUBLISHER]