The role of DNA profiling in monitoring grain quality

Studying microbial communities on grain

The bacteria and fungi that make up microbial communities on grains are quite diverse. Some of these microorganisms contribute to the health of plants and soils, some cause harm and others have no known effects. When we find an unfamiliar bacterium or fungus on grain, we determine its DNA makeup through a process called sequencing. The DNA of the microorganism under investigation is compared to that of related species to determine how it differs (Figure 1). We can then target the differences in the DNA using highly specific tests that can accurately distinguish between two DNA sequences. We use the results of these tests to create a DNA profile that is unique for a certain species and can be used to identify it in a sample (Figure 2).

Our high-throughput robotic systems allow us to accurately and efficiently perform DNA tests on thousands of Canadian grain samples every year (Figure 3). The data generated from these tests help us monitor disease-causing organisms in grain more accurately. For example, we have been able to determine the geographical and temporal trends in the fungal species responsible for Fusarium head blight in Canadian wheat (Figure 4). This disease can affect the yield, quality and safety of grain. Understanding how Fusarium species vary across regions and time plays an important role in its management.

The genome data we collect also gives us detailed information about the biology of microorganisms that can be used to assess risks and benefits to crop quality and safety. For example, we can determine which species contain the genes responsible for certain diseases or toxins. Understanding plant pathogens on a genomic level helps producers, breeders, pathologists, and agronomists develop mitigation strategies that target emerging species and strains.

DNA testing of grain varieties

Varieties of grain that are indistinguishable from each other based on physical characteristics or chemical analysis can still differ in their end-use qualities. The DNA-based tests that we develop enable us to accurately identify all varieties present in grain samples, including new varieties of grain that are developed and released by breeders. By sequencing the genomes of new crop varieties (Figure 1), we can detect differences in their DNA and use this information to perform thousands of targeted DNA genotyping tests at the same time (Figure 2). The genome information we gather is also used to identify the genes responsible for traits that are in demand, which helps breeders develop new varieties that meet the changing needs of producers and customers of Canadian grain.