Variety Identification (ID) tests maintain the integrity of seed varieties in the market. Making sure crop varieties remain pure has important implications across the supply chain. Seed companies want to offer varieties that match the needs of farmers. Farmers want to buy seed varieties that contain traits adapted to their region’s climate, soil properties, and disease pressures.
Under ideal growing conditions, locally adapted varieties will be higher yielding and produce higher quality seed. This, in turn, will directly benefit consumers. For example, food ingredient companies will create higher quality products when they use varieties that were specifically designed for consumers. In contrast, accidental variety mixtures or mislabeled seed can disrupt production at the farm and reduce quality at the dinner table.
Thus, seed Variety ID tests are an important step in quality control and assurance before the next growing season.
What Are Seed Variety ID Tests?
There are two general types of Variety ID tests: field inspections and genetic tests. The best way to maintain a variety’s integrity year after year is to perform both types of Variety ID tests.
During the growing season, field inspectors evaluate whether the plants display traits described for a particular variety. These visible traits may consist of plant height, leaf and stem color, flower size and color, disease tolerance, and maturity group. Ideally, fields used for seed production should be isolated from other varieties of the same crop and remain free of noxious weeds.
After harvest, a subsample of seed is sent to a seed laboratory, such as the North Dakota State Seed Department. They identify any contaminants of non-crop seed as well as perform germination tests.
A final, but important, step is to use a DNA or genetic test. The genetic test compares DNA profiles of the submitted seed to a known variety standard, and a match confirms the seed is the expected variety. In some states, such as North Dakota, genetic tests are necessary for certification labeling of seed lots.
How Are Genetic Tests Developed for Seed Variety ID?
Finding and selecting genetic markers for seed Variety ID tests requires extensive research. Seed standards from all available varieties are used during test development to find genetic markers that provide unique DNA profiles, known as genotypes, for each variety. All confirmed genotypes for varieties are saved to a large database.
Each year, thousands of seed lots are genotyped, and these profiles are compared to the large database to search for a variety match. The variety match for the seed lot is provided in a professional and confidential report. The report lets the owner know if the seed lot matches the expected variety and whether it may contain a possible mixture of at least two varieties.
How Does a Lab Perform Genetic Tests for Variety ID?
There are multiple genetic or genotyping methods that can be used to confirm seed variety. Across all methods, the first step is to extract DNA from a subsample of seeds. To start, seeds are ground into a fine powder. Next, a subsample of seed powder is subjected to a series of chemical digestion and purification steps to remove contaminants (proteins, lipids) leaving behind purified DNA for use in genetic tests.
Next, purified DNA is evaluated at several genetic markers. There are multiple types of markers that can be used, but SSRs (simple sequence repeats) are often selected because they are highly variable among varieties and found throughout the genome.
The SSRs for genotyping seed are characterized by using a stepwise method called polymerase chain reaction (PCR). As PCR progresses, fluorescent tags are attached to SSRs, allowing a light-sensitive machine to assign genotypes based on the length of SSRs within samples. This genotype is compared to the large genotype database to search for a match.
Interpretation of the results may be: 1) confirmation of the expected variety, 2) unexpected match to a different variety, 3) mixture of at least two varieties.
Seed Variety ID Tests From an Accredited Genotyping Testing Laboratory
The National Agricultural Genotyping Center (NAGC) continues to expand their capabilities in Variety ID testing. Currently, NAGC accepts cleaned seed for Variety ID testing in Wheat, Barley, and Field Pea. All three crops require genetic tests for registered and certified seed labeling in North Dakota.
NAGC has also begun validations to develop Variety ID tests for Chickpea and Durum to assist in quality control for seed sales and food ingredients. Thus, NAGC offers a dynamic collection of Variety ID tests under the categorical name: CropFilers.
If in need of independent seed Variety ID testing as a state seed lab, seed company, breeder, or private grower, send NAGC seed for genetic tests. The family of CropFiler tests will work on harvested seed and leaf tissue from the field or greenhouse.
Use this Variety ID testing submission form to submit your seed or tissue sample. Please call or email NAGC for questions about our lineup of CropFiler testing services.