DNA-based testing provides assurance of grain quality

Detecting multiple GM events in soybeans

The number of new GM events in soybeans and canola has been steadily increasing since the mid-1990’s and we currently have validated methods for detecting and quantifying 18 different GM events in soybeans (Table 1). These methods are based on polymerase chain reaction (PCR) and have a limit of detection and limit of quantification of 0.05%.

The PCR detection of each GM event in a single soybean sample can be time consuming but our methods allow us to detect many GM events at the same time. We dispense the required primer and probe concentrations into 96-well plates and freeze them. After the addition of the sample DNA and other ingredients needed for testing, we analyze the sample DNA for all 18 GM events using four PCR tests for each event. Once the positive GM events in the sample are identified, we determine their quantities using a real-time quantitative PCR assay. Our lab uses the QuantStudio^TM 7 Pro real-time PCR system to detect and quantify GM events in grain samples (Figure 1). This equipment has improved our capacity for PCR testing and is a replacement for the Applied Biosystems^TM 7500 System that was used in our lab from 2004 to 2023.

Varietal purity of CDC Copeland

Variety is an important consideration when barley is selected for malting purposes and most buyers require a minimum of 95% varietal purity. The purity of the variety CDC Copeland recently became a major concern when a relatively high percentage of an undesignated DNA profile was found in some samples from the 2022 growing season. We collaborated with the Grain Research Laboratory’s Microbiology and Grain Genomics Program, the Canadian Food Inspection Agency, breeders and industry partners to test samples of CDC Copeland for this undesignated DNA profile. It was subsequently confirmed that initial breeder seed of CDC Copeland contains low levels of the undesignated DNA profile and that its presence was not a contamination event. A study by the Grain Research Laboratory’s Barley and Other Grains Research/Milling and Malting Program found that the grain and malting characteristics did not differ in samples of CDC Copeland with high levels of the undesignated DNA profile. We also collaborated with the Barley and other Grains Research/Milling and Malting Program in testing selected cargo and harvest samples.

Technology used for varietal identification monitoring

The cooperation of breeders in supplying samples of the new breeder seeds of barley and wheat is essential to ensure that all varieties are represented in our database.

For many years we assessed the varietal purity of barley samples using a Li-Cor system that is based on DNA markers called microsatellites. Although this method is precise, it is not efficient since only a limited number of samples can be analyzed at one time. The Takara SmartChip system validated by the Grain Research Laboratory’s Microbiology and Grain Genomics Program is now being used since it allows high throughput identification of Canadian barley varieties using 24 DNA markers.

To test wheat cargo samples, we use OpenArrayTM genotyping technology and have the DNA profiles of many wheat varieties in our database. As new varieties are released this database is updated.

Recent monitoring activities

Between August 1, 2022, and July 31, 2023, we analyzed the variety composition of the following:

• 612 samples from wheat cargo, with 178 samples re-tested (drill down testing)
• 200 samples from durum cargo
• 36 samples of cargo aggregates (previously called monthly cargo composites)
• 60 samples for wheat co-op trials
• 68 wheat samples from the Harvest Sample Program
• 23 submitted barley cargo samples

In addition, 76 wheat cargo samples were analyzed for the presence of the MON71200 GM event. This GM event has not been detected since testing for it started in 2018, but wheat exporters can request testing on a fee for service basis.