Test Overview
Duration: Variable depending on test
Immunoassays use antibodies to detect specific proteins. At the Iowa State University Seed Laboratory, immunoassays are used for both biotech trait testing and the detection of certain seedborne pathogens.
Two common immunoassay formats are ELISA (Enzyme-Linked Immunosorbent Assay) and lateral-flow strips (immunostrips). The appropriate method depends on the crop, target, and purpose of the test.
Biotech Trait Testing
Immunoassays can detect proteins produced by specific biotech traits. Depending on the testing objective, they may be used to determine whether a trait is present or absent or to estimate the percentage of seed expressing a particular trait.
Individual seeds or leaves may be tested when evaluating trait purity. Pooled seed samples may be tested when screening for the presence or absence of a trait.
Seed Health Testing
Immunoassays may also be used to detect specific seedborne pathogens, particularly viruses and some bacteria. Seed extracts are tested using antibodies that specifically recognize the target pathogen.
Test Details
ELISA
For ELISA testing, seed or plant tissue is prepared in an extraction buffer. The extract is placed into wells containing antibodies specific to the target protein or pathogen. A measurable color reaction indicates whether the target has been detected.
ELISA is well suited for testing multiple samples and for applications requiring individual seed or plant testing.
Lateral-Flow Strips
Lateral-flow strips provide a rapid antibody-based method for detecting specific target proteins. Seed or plant material is prepared in an extraction solution and the strip is used to determine whether the target protein is detected.
Single-target strips or strips capable of detecting multiple traits may be used depending on the testing objective.
The appropriate immunoassay is selected based on the crop, target, required sensitivity, and testing objective.
Sample Requirements
Sample requirements vary considerably depending on the crop, target, testing method, and number of seeds being evaluated.
For Seed Health testing, sample requirements are dependent on the crop and pathogen.
For Trait testing, sample requirements depend on the testing objective and the statistical level of detection or trait purity required.
Contact Customer Care if you are unsure of the amount of seed required for your test. Additional seed may be required when multiple tests are requested on the same sample.