The existence of transgenic hybrids resulting from transgene escape from genetically modified (GM) crops to wild or weedy relatives is well documented but the fate of the transgene over time in recipient wild species populations is still relatively unknown. This is the first report of the persistence and apparent introgression, i.e. stable incorporation of genes from one differentiated gene pool into another, of an herbicide resistance transgene from Brassica napus into the gene pool of its weedy relative, Brassica rapa, monitored under natural commercial field conditions. Hybridization between glyphosate-resistant [herbicide resistance (HR)]B. napus and B. rapa was first observed at two Québec sites, Ste Agathe and St Henri, in 2001. B. rapa populations at these two locations were monitored in 2002, 2003 and 2005 for the presence of hybrids and transgene persistence. Hybrid numbers decreased over the 3-year period, from 85 out of approximately 200 plants surveyed in 2002 to only five out of 200 plants in 2005 (St Henri site). Most hybrids had the HR trait, reduced male fertility, intermediate genome structure, and presence of both species-specific amplified fragment length polymorphism markers. Both F(1) and backcross hybrid generations were detected. One introgressed individual, i.e. with the HR trait and diploid ploidy level of B. rapa, was observed in 2005. The latter had reduced pollen viability but produced approximately 480 seeds. Forty-eight of the 50 progeny grown from this plant were diploid with high pollen viability and 22 had the transgene (1:1 segregation). These observations confirm the persistence of the HR trait over time. Persistence occurred over a 6-year period, in the absence of herbicide selection pressure (with the exception of possible exposure to glyphosate in 2002), and in spite of the fitness cost associated with hybridization.

Cannabis sativa L. is a diploid species, cultivated throughout the ages as a source of fiber, food, and secondary metabolites with therapeutic and recreational properties. Polyploidization is considered as a valuable tool in the genetic improvement of crop plants. Although this method has been used in hemp-type Cannabis, it has never been applied to drug-type strains. Here, we describe the development of tetraploid drug-type Cannabis lines and test whether this transformation alters yield or the profile of important secondary metabolites: Δ 9 -tetrahydrocannabinol (THC), cannabidiol (CBD), or terpenes. The mitotic spindle inhibitor oryzalin was used to induce polyploids in a THC/CBD balanced drug-type strain of Cannabis sativa . Cultured axillary bud explants were exposed to a range of oryzalin concentrations for 24 h. Flow cytometry was used to assess the ploidy of regenerated shoots. Treatment with 20–40 μM oryzalin produced the highest number of tetraploids. Tetraploid clones were assessed for changes in morphology and chemical profile compared to diploid control plants. Tetraploid fan leaves were larger, with stomata about 30% larger and about half as dense compared to diploids. Trichome density was increased by about 40% on tetraploid sugar leaves, coupled with significant changes in the terpene profile and a 9% increase in CBD that was significant in buds. No significant increase in yield of dried bud or THC content was observed. This research lays important groundwork for the breeding and development of new Cannabis strains with diverse chemical profiles, of benefit to medical and recreational users.

The distribution and abundance of three Camelina species introduced to Canada is unknown, but critical for evaluating the risks associated with unconfined release of transgenic Camelina sativa (L.) Crantz (2n = 40). Furthermore, previous reports suggest Canadian populations of Camelina microcarpa Andrz. ex DC. vary for ploidy and ability to hybridize with C. sativa. We completed 8 weeks of field work in Alberta, Saskatchewan, Manitoba, southern Ontario, Quebec, and the Maritimes. We determined the ploidy composition of the populations found. We did not locate Camelina alyssum (Mill.) Thell., but located four sites with C. sativa and 34 with C. microcarpa. Eleven C. microcarpa populations were tetraploid (2n = 26, 1.00pg/2C) and 22 were hexaploid (2n = 40, 1.50pg/2C), while two populations were mixed. We examined material from botanical gardens and plant gene resource centres assessing total nuclear DNA content and completing chromosome counts for each species and cytotype identified, to determine whether tetraploid and hexaploid C. microcarpa were included in these collections. No tetraploid material was included in the C. microcarpa accessions received; however, a diploid (2n = 12, 0.54pg/2C) was found. Given the current geographic ranges, abundance, and chromosome counts of these species, the greatest risk of hybridization with transgenic C. sativa is from hexaploid C. microcarpa.

Information on genetic diversity and genetic relationships among taxa of Brassica rapa (n ¼ 10, AA genome) is currently limited. Grown for oil, vegetable and fodder use in Europe and Asia, previous studies have indicated western and eastern groups corresponding to independent centres of origin. This study evaluated patterns and levels of genetic diversity in 93 accessions [includes 25 Agriculture and Agri-Food Canada (AAFC) breeding lines (BL)] of B. rapa based on 307 amplified fragment length polymorphisms (AFLP), testing subspecific separateness and the affiliation of four previously unassigned AA genome species (B. perviridis, B. purpuraria, B. ruvo and B. septiceps). AFLP data revealed three main clusters (I, II, III) corresponding to European (I), Indian (III), and a mixed Asian/European/Indian (II) purported origins of the taxa, with several subclusters observed in I and II. Mean AFLP polymorphism levels for Asian, European, Indian and AAFC-BL accessions were 79, 74, 66 and 62%, respectively. Few of the subspecies formed unique clusters and some, particularly subspecies chinensis and pekinensis, were assigned to several clusters. AFLP-based genetic distance information can be used by breeders to select diverse genotypes for cultivar development and fingerprinting of genotypes/cultivars. For example, a single AFLP primer pair was sufficient to uniquely identify all breeding lines in the AAFC B. rapa breeding programme.

Hybridization between crops and their wild relatives has the potential to introduce novel variation into wild populations. Camelina ( Camelina sativa ) is a promising oilseed and cultivars with modified seed characteristics and herbicide resistance are in development, prompting a need to evaluate the potential for novel trait introgression into weedy relatives. Little‐podded false flax (littlepod ; Camelina microcarpa ) is a naturalized weed in Canada and the USA. Here we evaluated the hybridization rate between the three cytotypes of littlepod (♀) and camelina (♂), assessed characteristics of hybrids, and evaluated the fitness of hexaploid littlepod and camelina hybrids in the glasshouse and field. In total we conducted, 1,005 manual crosses with diploid littlepod, 1, 172 crosses with tetraploid littlepod, and 896 crosses with hexaploid littlepod. Hybrids were not produced by the diploids, but were produced by the tetraploids and hexaploids at rates of one hybrid for 2,000 ovules pollinated and 24 hybrids for 25 ovules pollinated, respectively. Hybrids between tetraploid littlepod and camelina showed low pollen fertility and produced a small number of seeds. In the glasshouse, hybrids between hexaploid littlepod and camelina also showed significantly lower pollen fertility and seed production than parental lines, but their seeds showed high viability. A similar pattern was observed in field trials, with hybrids showing earlier flowering, reduced biomass, seed production and seed weight. However, seed produced by the hybrids showed greater viability than that produced by hexaploid littlepod and is potentially the result of a shortened lifecycle. The introgression of lifecycle traits into littlepod populations may facilitate range expansion and contribute to crop gene persistence. Consequently, future work should evaluate the hybridization rate in the field, the fitness of advanced generation backcrosses, and the role of time to maturity in limiting hexaploid littlepod's distribution.