An integrated strategy involving high-throughput sequencing to characterize an unknown GM wheat event in Canada.

Glyphosate-resistant wheat plants were discovered in southern Alberta in 2017, representing an unauthorized GM release in Canada. The Canadian Food Inspection Agency undertook a series of experiments to characterize and identify this unknown GM wheat, as well as to develop and validate construct-specific and event-specific qPCR assays. Results of PCR-based assays and Sanger sequencing indicated the presence of CaMV 35S promoter (p35S), Rice Actin 1 intron (RactInt1), CP4-EPSPS gene and nopaline synthase terminator (tNOS) elements in the unknown GM wheat. Genome walking and bead capture strategies, combined with high-throughput sequencing, were used to identify the 5' and 3' wheat junctions and the subsequent mapping of the insert to chromosome 3B of the wheat genome. A probable transformation vector, pMON25497, was recognized, and further testing identified the unknown GM wheat as MON71200 event, one of two events obtained with the pMON25497 vector. The two construct-specific assays targeted the junctions of the RactInt1 and the CP4-EPSPS elements and the CP4-EPSPS and tNOS elements, while the event-specific assay was located at the 3' junction into the wheat genome. Both construct-specific and event-specific assays had limits of detection of 0.10% of MON71200 in a seed pool. As expected, the two construct-specific assays cross-reacted with other wheat and corn events containing the same elements in the same order. No cross-reactivity was observed for the event-specific assay. The integrated strategy employed in this study can serve as a model for other cases when facing similar challenges involving unknown GM events.

The Molecular Data Organization for Publication (MDOP) R package to aid the upload of data to shared databases.

Molecular identification methods, such as DNA barcoding, rely on centralized databases populated with morphologically identified individuals and their referential nucleotide sequence records. As molecular identification approaches have expanded in use to fields such as food fraud, environmental surveys, and border surveillance, there is a need for diverse international data sets. Although central data repositories, like the Barcode of Life Datasystems (BOLD), provided workarounds for formatting data for upload, these workarounds can be taxing on researchers with few resources and limited funding. To address these concerns, we present the Molecular Data Organization for Publication (MDOP) R package to assist researchers in uploading data to public databases. To illustrate the use of these scripts, we use the BOLD system as an example. The main intent of this writing is to assist in the movement of data, from academic, governmental, and other institutional computer systems, to public locations. The movement of these data can then better contribute to the global DNA barcoding initiative and other global molecular data efforts.

Detection and identification of multiple genetically modified events using DNA insert fingerprinting.

Current screening and event-specific polymerase chain reaction (PCR) assays for the detection and identification of genetically modified organisms (GMOs) in samples of unknown composition or for the detection of non-regulated GMOs have limitations, and alternative approaches are required. A transgenic DNA fingerprinting methodology using restriction enzyme digestion, adaptor ligation, and nested PCR was developed where individual GMOs are distinguished by the characteristic fingerprint pattern of the fragments generated. The inter-laboratory reproducibility of the amplified fragment sizes using different capillary electrophoresis platforms was compared, and reproducible patterns were obtained with an average difference in fragment size of 2.4 bp. DNA insert fingerprints for 12 different maize events, including two maize hybrids and one soy event, were generated that reflected the composition of the transgenic DNA constructs. Once produced, the fingerprint profiles were added to a database which can be readily exchanged and shared between laboratories. This approach should facilitate the process of GMO identification and characterization.

Identification of genetically modified potato (Solanum tuberosum) cultivars using event specific polymerase chain reaction.

Several genetically modified (GM) cultivars are registered in Canada although they are not currently in commercial production. The GM cultivars can be distinguished from the non-GM and other GM cultivars by analyzing the DNA nucleotide sequence at the insertion site of the transgene corresponding to a single transformation event in the plant genome. Techniques based on modified polymerase chain reaction (PCR) strategies were used to generate sequence information from the plant genome flanking the insertion site of transgenic DNA for specific GM potato events. The plant genome sequence adjacent to the transgenic insertion was used to design PCR primers, which could be used in combination with a primer annealing to one of the nearby inserted genetic elements to amplify an event specific DNA fragment. The event specific PCR fragments generated were sequenced to confirm the specificity of the method.

Identification of Monilinia fructigena, M. fructicola, M. laxa, and Monilia polystroma on Inoculated and Naturally Infected Fruit Using Multiplex PCR.

Monilinia fructigena, M. fructicola, M. laxa, and Monilia polystroma each have a different regulatory status. To monitor imported and exported fruit for the presence of quarantined Monilinia or Monilia species, a timely identification method is required. Random amplified polymorphic DNA analysis was used to generate an M. fructigena-specific band that was characterized by sequencing. Using the sequence obtained, primers were designed to amplify bands in the same genomic region of M. fructicola and M. laxa. These bands were also characterized by sequencing. From all three sequences, a multiplex polymerase chain reaction (PCR) method based on a common reverse primer (MO368-5) and three species-specific forward primers (MO368-8R, MO368-10R, and Laxa-R2) was established for the differentiation of the three Monilinia species. The multiplex PCR was tested with additional isolates and consistently produced a 402-bp PCR product for M. fructigena, a 535-bp product for M. fructicola, and a 351-bp product for M. laxa. The method was also used with isolates of the recently characterized Monilia polystroma, and all isolates amplified a 425-bp PCR product. The identification method was shown to amplify a PCR product directly from inoculated apples, and the PCR band produced was specific to the inoculated Monilinia or Monilia species. Furthermore, the multiplex PCR was used to identify Monilinia species on naturally infected stone fruits. The method correctly identified infections by both M. laxa and M. fructicola by successful amplification of corresponding PCR products for each species.

Variations in sequence and occurrence of SSU rDNA group I introns in Monilinia fructicola isolates.

A group I intron of 418 base pairs in the Monilinia fructicola ribosomal small-subunit sequence was characterized. The absence of such an intron in M. laxa and M. fructigena led to a PCR test for M. fructicola identification based on the presence of this intron. The failure to amplify a PCR fragment for some isolates of M. fructicola recently lead to speculation that the intron might not be present always in M. fructicola. In this study, we analyzed 13 isolates of M. fructicola and found that the intron was absent in four isolates and we determined from sequence analysis that there are several nucleotide variations that allow the M. fructicola ribosomal SSU intron to be grouped into 6 polymorphic types.